Browsing by Author "Ngubane, Phikelelani Siphosethu."

Now showing 1 - 9 of 9

The acute effects of dioxidovanadium on blood glucose concentration and oxidative stress in the hippocampus of non-diabetic male Sprague Dawley rats and the chronic effects of dioxidovanadium on selected markers associated with hippocampal dysfunction in male streptozotocin-induced diabetic rats.
(2022) Dayanand, Yalka.; Ngubane, Phikelelani Siphosethu.; Khathi, Andile.; Sibiya, Ntethelelo Hopewell.
Diabetes mellitus is a disease associated with derangements in glucose metabolism and chronic hyperglycaemia. Chronic hyperglycaemia induces oxidative stress and inflammation that affect glucose sensitive hippocampal neurons resulting in generation of amyloid plaques and tau tangles. These are the primary markers used in the detection of neurodegenerative diseases such as Alzheimer’s and dementia. Hence, there is a strong correlation between diabetes and memory impairment. Current therapeutic options such as bolus insulin have been successful in the management of the disease. Despite the efficacy of these therapies, they however have been shown to possess undesirable effects that exacerbate the secondary pathological effects of diabetes on the hippocampus thereby contributing to the detriment of cognitive tasks such as learning and memory. Therefore, there is a need to explore alternative treatments. Transition metals have been shown to possess therapeutic effects with vanadium possessing the greatest potency in lowering blood glucose concentrations. However, studies have demonstrated toxic accumulation of vanadium in the hippocampus which result in the generation of oxidative stress and neurodegeneration. In our laboratory, we have synthesised dioxidovanadium (V) complex by attaching organic ligands to reduce the toxicity and improve potency of the metal. This complex has been shown to efficiently reduce blood glucose and elicit cardio and reno-protective properties. Despite these advancements the effects of this complex on the hippocampus and learning and memory are yet to be established. Therefore, in this study the aim was to evaluate the effect of dioxidovanadium complex on selected learning and memory parameters. Methodology The effect of vanadium on the brain was studied acutely and chronically. In the acute study, animals were separated into 2 groups, non-diabetic control group and a non-diabetic animal group which was were treated with vanadium complex (40 mg.kg-1 p.o). The treatment was administered at time 0. Subsequently an n=3 from each group was sacrificed at regular time intervals (1 hour, 2 hours, 6 hours, 24 hours, 5 days, 10 days) in each group. Blood glucose concentration was monitored before sacrificing and hippocampal tissue was harvested for malonaldehyde (MDA) analysis and glutathione peroxidase (GPx1) and tumour necrosis alpha (TNF-α). The second study was conducted over 5 weeks and consisted of an untreated non-diabetic control, a diabetic control, a positive insulin treated group (0.175 mg.kg-1 s.c) and two dioxidovanadium (V) treated groups (40 mg.kg-1 p.o), a non-diabetic and a diabetic group. Blood glucose was monitored weekly and the Morris water maze was conducted on the last week of the study. After 5 weeks the animals were sacrificed and hippocampal tissue was harvested for malonaldehyde (MDA) analysis, glutathione peroxidase (GPx1) tumour necrosis alpha (TNF-α), amyloid beta (Aβ) and hyperphosphorylated tau (pTau) ELISA’s. Results Acutely, dioxidovandium (V) did not lower blood glucose significantly in comparison to the control group. Interestingly, MDA, GPx1 and (TNF-α) were also not significantly different from the control group over all time periods in the study. Chronically, the glucose concentration of the dioxidovandium (V) treated diabetic group was significantly lowered when compared to the untreated group which displayed significantly increased glucose concentration in comparison to the non-diabetic control. The non-diabetic dioxidovanadium (V) treated group did not show a significant difference in glycaemic level. Increased MDA concentration in the diabetic group was significantly lowered by dioxidovanadium(V) treatment. GPx1 concentration in the dioxidovanadium (V) treated group significantly improved in comparison to the diabetic untreated control. The non-diabetic dioxidovandium (V) treated group showed no significant change in MDA and Gpx1 after the 5-week period. There was no significant difference in TNF-α in dioxidovanadium (V) treated groups, diabetic and non-diabetic. The concentration of Amyloid β was significantly lower in the diabetic control when compared to the non-diabetic control. The dioxidovanadium (V) treated groups, both diabetic and non-diabetic did not have a significant difference in comparison to the diabetic control. pTau concentrations in all groups did not significantly differ. Latency times for the last day of training the Morris water maze followed the same trend. The probe test results, which measured spatial memory, for the diabetic untreated and dioxidovanadium (V) treated groups were significantly reduced in comparison to the non-diabetic control group. The non-diabetic untreated and non-diabetic dioxodivanadium (V) treated were not significantly different. Conclusion Dioxidovanadium (V) treatment in non-diabetic animals did not induce hypoglycaemia acutely however reduced blood glucose concentration in diabetic animals when administered chronically. Dioxidovanadium (V) did not induce oxidative stress and may protect against neurodegeneration by enhancing antioxidant status and therefore was considered as a pro-oxidant in the hippocampus.
An investigation on the effects of a rhenium (V) compound with uracil-derived ligands on markers associated with hepatic, cardiovascular and renal complications in diet-induced prediabetic rats.
(2023) Siboto, Angezwa.; Khathi, Andile.; Ngubane, Phikelelani Siphosethu.; Sibiya, Ntethelelo Hopewell.
Prediabetes is a metabolic disorder that often precedes the onset of type 2 diabetes mellitus. This development of this asymptomatic condition is associated with chronic consumption of high calorie diets and sedentary lifestyles. Prediabetes results in decreased insulin sensitivity in the peripheral tissues resulting in elevated blood glucose levels that are not high enough for a diagnosis of type 2 diabetes. This moderate hyperglycaemia has been shown to lead to trigger complications such as non-alcoholic fatty liver disease, renal dysfunction and cardiovascular disease which are generally only diagnosed during type 2 diabetes. The current management strategy for prediabetes consists of a combination of pharmacological and lifestyle intervention. The pharmacological agents such as metformin while lifestyle intervention involves dietary modification to lower calorie diets. Studies show that prediabetic patients tend to be more dependent pharmacological intervention and struggle with changing diets thus lowering the efficacy of drugs such as metformin. This often leads to the eventual development of prediabetes. Therefore, there is a need for new pharmacological agents that can remain effective in both the presence and absence of dietary intervention. In our laboratory we have synthesised a novel rhenium (v) compound with uracil-derived ligands that has shown promising biological activities that include anti-hyperglycaemic effects in diet-induced prediabetic rats. This compound was shown to improve insulin sensitivity in peripheral tissues in prediabetic rats. To advance from this knowledge, this study sought to investigate the effects of the rhenium (V) compound with uracil-derived ligands on markers associated with hepatic, cardiovascular and renal complications in diet induced prediabetic rats model.
The changes in immune cells concentration during the progression of pre-diabetes to type 2 diabetes in a diet-induced pre-diabetic rat model.
(2019) Mzimela, Nomusa Christina.; Khathi, Andile.; Ngubane, Phikelelani Siphosethu.
T2D has been discovered to be preceded by a long-lasting condition known as prediabetes. The primary cause of prediabetes and T2D has also been shown to be continuous consumption of unhealthy diets and living a sedentary lifestyle. Type 2 diabetic patients have been discovered to have a supressed immune system, but it is still debatable whether immune activation begins at the pre-diabetes stage or during overt T2D. According to literature, T2D is a result of elevated levels of glucose known as hyperglycaemia caused by a condition called insulin resistance. Additionally, T2D has also been shown to be characterised by increased levels of triglycerides, low density lipoproteins (LDL) and decreased levels of high-density lipoproteins (HDL). Insulin resistance then causes metabolic and signalling pathways such as oxidative stress, activation of PKC pathway, formation of advanced glycation end products (AGEs) and shunting of polyol pathway which trigger metabolic inflammation resulting in a dysregulated innate immunity. Dysregulated innate immunity in T2D patients has also been discovered to be due immune response caused by hyperglycaemia. However, it has not been discovered if immune activation occurs at the pre-diabetes stage. It has not been discovered if upregulation of inflammatory markers occurs at prediabetes stage. This study envisaged to characterise the changes that occur in immune cell concentration during the progression of pre-diabetic stage and if there is upregulation of inflammatory markers such as fibrinogen, CRP, CD40L, p-selectin, IL-6 and TNF-α during pre-diabetic stage. To accomplish this, male Sprague Dawley rats were divided into two groups. The first group was fed a high-fat high-carbohydrate diet for 20 weeks to induce pre-diabetes and the second group was fed a normal rat diet for 20 weeks. To confirm if the animals were pre-diabetic, criteria according to American Diabetes Association were used. The animals were then divided into 2 groups which is the pre-diabetic group with 6 animals and a non-diabetic control with another 6 animals. The animals were then further monitored for another 12 weeks (experimental period) while fed the same diet. Blood was collected for haemocytometer analysis on week 0,4,8 and 12 of the experimental periods after which the animals were sacrificed. Plasma was collected from centrifuged blood for ELISA (TNF- α, CRP, P-selectin, CD40 L, fibrinogen & IL-6). Adipose tissue was collected for histology. The results showed a significant decrease in blood percentage count of neutrophils and eosinophils at week 12 experimental period and these immune cells were further observed embedded in-between the adipocytes of adipose tissue. This indicated that neutrophils and eosinophils are produced due to hyperglycaemia and then recruited to the inflamed area such as adipose tissue. The blood percentage count of lymphocytes, basophils and monocytes showed a significant increase at week 12, indicating their increase in production in the bone marrow during immune response. Additionally, the results showed a significant increase in inflammatory cytokines such as TNF-α, IL-6, CRP and P-selectin. The results also showed a slight increase in inflammatory markers such as CD40L and fibrinogen. These finding indicate that there is immune activation during pre-diabetes stage due to changes in immune cells concentration and upregulation of inflammatory markers.
The effects of insulin and Syzygium aromaticum-derived oleanolic acid containing dermal patches on kidney function and renal expression of glucose transporters in streptozotocin-induced diabetic rats.
(2014) Ngubane, Phikelelani Siphosethu.; Musabayane, Cephas Tagumirwa.
Introduction The tight glycaemic control required to attenuate chronic complications in type 1 diabetes mellitus requires multiple daily injections of bolus insulin which have been reported to be associated with Na+ retention resulting in hyperinsulinaemic oedema and hypertension. Current research on insulin delivery methods include buccal, oral, nasal, and transdermal delivery systems. Transdermal delivery system is of great interest as this offers sustained controlled release of insulin into the systemic circulation. We have previously reported that transdermal application of pectin hydrogel insulin (PI) matrix patches sustain controlled insulin delivery into the bloodstream of STZ-induced diabetic rats to perhaps ameliorate diabetic complications. Since we have previously reported that STZ-induced diabetic rats retain Na+ following hypotonic saline challenge, this study investigated whether insulin-containing dermal patches can avert and improve the impaired renal fluid and electrolyte handling of STZ-induced diabetic rats. We have also shown that oral administration of OA in addition to possessing hypoglycaemic effects, improves kidney function STZ-induced diabetic rats. The study therefore also investigated whether OA-containing dermal patches can improve kidney function STZ-induced diabetic rats. Materials and methods Pectin insulin (PI)-containing dermal patches of various doses (3.99, 9.57, 16.80 μg/kg) and pectin oleanolic acid (P-OA) containing dermal patches of various doses (21, 42, 84 mg/kg) were prepared by dissolving pectin/insulin or pectin/OA in deionized water and solidified with CaCl2. Short-term (5 weeks) effects on renal function of thrice daily treatments with PI and P-OA patches 8 hours apart were assessed in diabetic animals. Rats sham treated with the pectin drug free patch and insulin (175 μg/kg sc) acted as negative and positive controls, respectively. Daily urine volume, urinary glucose, Na+, K+ and creatinine excretion rates were monitored over 5-weeks. Blood was collected 6 h following treatments for insulin determination. Blood and kidney samples were also collected after 5 weeks for hormonal analysis and measurement of selected biochemical parameters. Results Untreated STZ-induced diabetic rats exhibited elevated weekly urinary glucose, K+ outputs and depressed urinary Na+ outputs throughout the 5-week compared to non-diabetic control animals. Application of PI-containing dermal patches significantly increased urinary Na+ output and reduced urine volume and urinary outputs of glucose and K+ in weeks 4 and 5. Plasma AVP concentrations of untreated STZ-induced diabetic rats were significantly low at end of the 5-week experimental period by comparison with control non-diabetic animals while plasma aldosterone levels were significantly elevated. The highest dose of the insulin-containing dermal patch (16.80 μg/kg) significantly (p < 0.05) elevated plasma AVP concentrations while decreasing plasma aldosterone concentrations of STZ-induced rats by comparison to untreated STZ-diabetic rats. GFR of untreated STZ-induced diabetic rats was significantly decreased while plasma creatinine concentrations were significantly elevated by comparison to non-diabetic control animals. PI containing dermal patches increased GFR of STZ-induced diabetic rats with a concomitant reduction of plasma creatinine concentrations by comparison to untreated STZ-induced diabetic rats. Interestingly, P-OA dermal patches also increased GFR of STZ-induced diabetic rats while reducing plasma creatinine concentrations. The effects of both PI and P-OA containing dermal patch compared with subcutaneous insulin. Significant increase of MDA and decreases of SOD and GPx were found in the skin, kidney and heart tissues of STZ-diabetic animals as compared to non-diabetic control animals. PI (16.80 μg/kg) -treated STZ-induced diabetic animals however showed low concentrations of MDA and increased the activities of SOD and GPx in the skin, kidney and heart tissues compared to untreated STZ-induced diabetic animals. P-OA-treated STZ-induced diabetic animals similarly and significantly showed decreased MDA, and increased activity of antioxidant enzymes; SOD and GPx in skin, kidney and heart tissues. H and E kidney stained sections of untreated non-diabetic control, untreated STZ-induced diabetic rats and diabetic animals topically applied with insulin and OA-containing dermal patches were observed under light microscope. However, STZ-induced diabetic rats showed thickened basement membrane of the Bowmans capsule, thickened glomerular basement membrane and hypercellularity of the proximal tubules by comparison to the non-diabetic animals after 5 weeks of the study. Treatment with insulin containing dermal patches and subcutaneous insulin for 5 weeks however attenuated these features when compared with the untreated STZ-diabetic rats. Like PI dermal patches, OA containing dermal patches also ameliorated structural changes of kidney of STZ-induced diabetic rats. The increased urinary glucose concentrations of the untreated STZ-induced diabetic rats were associated with increased expression of GLUT 1 and SGLT 1 to normalcy by comparison to nondiabetic rats. The highest dose of PI containing dermal patch however, like subcutaneous insulin, significantly decreased the expressions of GLUT 1 and SGLT 1 by comparison to STZ-induced diabetic controls. Plasma insulin concentrations of untreated STZ-induced diabetic rats were significantly low in comparison with control non-diabetic animals. Acute (6 h) and short-term (5 weeks) daily application of PI containing dermal patches to STZ induced diabetic rats significantly elevated plasma insulin concentrations by comparison with untreated diabetic animals. However, the plasma insulin concentrations in animals treated with the high insulin doses (9.57, 16.80 μg/kg) were significantly higher than those found in diabetic groups treated with the low insulin dose (3.99 μg/kg). There were no differences in the plasma insulin concentrations in STZ-induced diabetic animals treated with P-OA containing dermal patches by comparison to STZ- diabetic untreated controls both acutely and chronically. To determine whether insulin was transported across skin of STZ-induced diabetic rats following topical application of PI and P-OA containing dermal patches, we also monitored the density of phosphorylated insulin receptor substrates (IRS) in the skin by immunohistochemical staining with specific insulin receptor antibodies. Non-diabetic treated skin sections showed slight immunostaining of insulin receptors in comparison STZ-induced diabetic rats which stained negative. Immunohistochemical staining for phosphorylated IRS in the skin of animals following application of insulin and sc insulin treatment for 5 weeks clearly demonstrated widespread localization of IRS in cell bodies of the dermis, collagen and subcutaneous layer. Interestingly, OA-containing dermal patches also showed widespread localization of IRS in cell bodies of the dermis, collagen and subcutaneous layer. H and E skin sections of untreated non-diabetic control, untreated STZ-induced diabetic rats and diabetic animals topically applied insulin and OA-containing dermal patches showed no significant histological differences in dermis compared to the untreated non diabetic control skin sections. Discussion Previous studies indicate compromised renal function in experimental diabetes and diabetic patients. The results herein however indicate that insulin containing dermal patches increase Na+ excretion probably by decreasing plasma aldosterone and increasing plasma AVP concentrations of STZ-induced diabetic rats. PI containing dermal patches also improve kidney function by increasing GFR with concomitant reduction of plasma creatinine concentrations. Like PI containing dermal patches, P-OA containing dermal patches increased Na+ excretion by decreasing plasma aldosterone and increasing plasma AVP concentrations of STZ-induced diabetic rats. P-OA containing dermal patches also increased GFR and reduced plasma creatinine concentrations of STZ-induced diabetic rats. Conclusion From these results, we conclude that PI and P-OA dermal patches deliver physiological amounts that can improve kidney function in diabetes.
Effects of Momordica balsamina methanolic extract on cardiovascular and haematological function in streptozotocin-induced diabetic rats: effects on selected markers.
(2018) Ludidi, Asiphaphola.; Ngubane, Phikelelani Siphosethu.; Khathi, Andile.
Background The hyperglycaemia-induced haemanetic changes reduces the oxygen-carrying capacity of erythrocytes, thus aggravating cardiovascular disorders in diabetic patients. The conventional therapies have been shown to be associated with the progression of haematological and cardiovascular dysfunction, which may not be favorable for patients with congestive heart failure. We have previously shown the anti-hyperglycaemic and antioxidant properties of Momordica balsamina (MB) methanolic extract which may be of benefit in alleviating cardiovascular disorders, thus providing an effective alternative therapy. The current study therefore, investigated the short-term effects of MB methanolic extract on cardiovascular and haematological function in streptozotocin-induced diabetic rats. Methods Briefly, air-dried MB leaves were extracted with methanol to yield a methanolic extract. STZ-induced diabetic rats were divided into untreated and treated groups with insulin (170 μg kg-1 s.c.) and metformin (500 mg kg-1 p.o.) as standard drugs. MB (250 mg kg-1 p.o.) was administered twice daily for 5 weeks. Blood glucose concentration, body weight and blood pressure were monitored weekly for 5 weeks. Terminally, animals were sacrificed after which blood, heart and kidneys were collected for haematological and biochemical analysis. Histological analysis was also performed on the hearts. Results MB significantly decreased blood glucose concentration from week 3-5 by comparison with diabetic untreated animals. Treatment with MB reduced oxidative stress in the plasma, kidney and heart while improving their antioxidant status compared with untreated diabetic animals. This was associated with increased EPO secretion by the kidneys thus improving RBC production and haemoglobin concentrations. MB moderately increased erythrocyte indices: mean cell volume (MCV), mean cell haemoglobin concentration (MCHC) and mean corpuscular haemoglobin (MCH) by comparison with untreated diabetic animals. MB ameliorated heart hypertrophy and decreased CRP, CT-I and Ang-II concentrations by comparison with untreated diabetic animals. MB also decreased MAP by comparison with untreated diabetic animals.Conclusion MB administration protects against hyperglycaemia-induced cardiovascular and haematological changes by attenuating hyperglycaemia, oxidative stress in both the kidney and heart tissues of STZ-induced diabetic rats, which may reduce the risks of cardiac myopathology complications in diabetes mellitus.
Effects of momordica balsamina on glucose handling in high fat high carbohydrate induced prediabetic rat model and glucose handling in C2C12 induced insulin resistant cell lines: effects on selected metabolic markers.
(2020) Khumalo, Bongiwe.; Ngubane, Phikelelani Siphosethu.; Khathi, Andile.; Sibiya, Ntethelelo Hopewell.
Increased consumption of fat and high carbohydrate coincided with increased prevalence in type 2 diabetes, a condition whose onset is always preceded by prediabetes. Prediabetes is best characterised by hyperglycaemia, insulin resistance and glucose intolerance. Prolong chronic hyperglycaemia exacerbates complications of increased oxidative stress, advanced glycation end products (AGE), dyslipidaemia, hyperinsulinemia and increased inflammatory markers. Once diagnosed, life style and dietary interventions strategies are one of the cornerstones in management of prediabetes. However, patients do not adhere to these life style changes. Hence the present study investigated the effects of Momordica balsamina (MB) on glucose handling in insulin resistance in C2C12 palmitic acid induced insulin resistant cell lines and in high fat high carbohydrate induced prediabetic rat model. Methods Briefly, air-dried MB leaves were extracted with methanol to yield methanolic extracts. The study was divided into 2 experimental series invitro, first series investigated the effects of MB compounds on cell viability in skeletal muscle cell lines. The second series investigated the effects of MB on glucose uptake in palmitic acid induced insulin resistant skeletal muscle cell lines. Invivo studies encompassed HFHC-induced diabetic rats which were divided into untreated and treated groups. The rats were treated with metformin (500 mg kg-1 p.o.) as standard drug and MB (250 mg kg-1 p.o.) a test drug. MB (250 mg kg-1 p.o.) was administered once every third day. Blood glucose concentration, body weight and calorie intake were monitored every fourth week for a period of 12 weeks. Terminally, animals were sacrificed after which blood, liver and skeletal muscle were collected for biochemical analysis. Results MB significantly decreased media glucose concentration whilst glycogen concentration was improved by comparison with insulin resistant cells. Treatment with MB reduced tissue damage which was shown MDA in the plasma while also improving their antioxidant status compared with insulin resistant cells. In vivo study, we measured caloric intake, body weights, ghrelin concentration, OGT response, glycogen concentration, GLUT 4, glycogen synthase, HOMA2- IR value and glycated haemoglobin (HbA1c) concentration. Interestingly, Momordica balsamina coupled with dietary intervention resulted in decreased fasting glucose concentration, suggesting improvement in insulin sensitivity. Reduced caloric intake and restored a steady constant weight growth, thus preventing obesity. This was associated with decreased plasma ghrelin levels. Additionally, there was a significant decrease in HOMA2-IR value. This was further evidenced by decreased levels of glycated haemoglobin in the MB-treated rats. Conclusion The results obtained suggests that Momordica balsamina (MB) possesses anti-hyperglycaemic and protective properties in vivo and in vitro, therefore could be potent in the management of prediabetes, impaired glucose homeostasis induced hyperglycaemia. In addition, these findings provide new scope to comprehensively delineate the medicinal plant, Momordica balsamina mechanism of activity.
Evaluation of the therapeutic properties of a Ruthenium(ll) uracil-derived diimine complex on selected complications associated with diet-induced pre-diabetes.
(2019) Mabuza, Lindokuhle Patience.; Khathi, Andile.; Ngubane, Phikelelani Siphosethu.
Pre-diabetes is a chronic metabolic condition where blood glucose levels are above the upper threshold considered normal but below the threshold for a diagnosis of diabetes. Pre-diabetes predisposes individuals to a high probability of future progression to overt T2DM. Pre-diabetic patients are at increased risk of developing other pathologies such as NAFLD, diabetic nephropathy (DN) and immune dysregulation complications. As a chronic disease, the long-term implications of diabetes contribute to poor quality of life and significantly increase costs associated with healthcare. Pre-diabetes may however be reversible, through the implementation of lifestyle modification programmes based around dietary modification and increased physical activity. Where lifestyle modifications are ineffective, both pharmacotherapy and lifestyle modification are recommended. However, there is reported poor patient compliance in terms of dietary intervention as patients tend to heavily rely on the pharmacological treatment, thus reducing the efficacy of the drug and increasing the possibility to develop T2DM. Hence, there is a need for novel drugs that will remain therapeutic even in the absence of dietary modification. In our laboratory, we have synthesized a novel ruthenium(II) uracil-derived diimine complex that has been shown to improve insulin sensitivity and restore glucose homeostasis in diet-induced prediabetes. In this study, we further sought to evaluate the effects of this compound on selected complications associated with diet-induced pre-diabetes. Estimating whether ruthenium(II) uracil-derived diimine complex in both the presence and/or absence of dietary intervention will show to be effective in the management of prediabetic-related complications. A high fat high carbohydrate (HFHC) diet was used to induce pre-diabetes for 20 weeks. After the induction, pre-diabetic rats were randomly allocated to the following treatment groups: non-prediabetes (NPD); pre-diabetic (PD); metformin plus HFHC; metformin plus normal diet (ND); Ruthenium plus HFHC and ruthenium plus ND. The animals were treated with subcutaneous injection of ruthenium complex (15 mg/ kg) and oral dose of metformin (500 mg/ kg). The rats were treated once a day every third day at 09:00 am for 12 weeks. Every 4 weeks, parameters such as body weight, food intake, fasting blood glucose, fluid intake and urinary output were monitored for 12 weeks treatment period. In study 1, the administration of ruthenium(II) complex resulted in the restoration of liver and body weights in the pre-diabetic treated rats when compared to the PD group. This treatment also reduced liver damage enzyme biomarkers and plasma total bilirubin levels in the pre-diabetic treated rats when compared to the PD group whilst administration of ruthenium(II) with dietary intervention reduced plasma sterol regulatory element binding protein 1c (SREBP-1c) concentration in the pre-diabetic treated rats when compared to the PD group. These findings were further supported by the histological analysis of the liver, showing reduced hepatic lipid droplet accumulation, hepatocyte ballooning and locular disarray in the ruthenium(II)-treated rats when compared to the PD group as seen in chapter 2 of the study. In study 2, the administration of ruthenium(II) complex resulted in reduced blood glucose, aldosterone, fluid intake and urinary output in the pre-diabetic treated rats when compared to the PD group which positively correlated with a restoration in plasma and urinary electrolytes along with plasma antioxidants concentrations in the ruthenium(II)-treated rats. Furthermore, there was a decrease in kidney injury molecular-1 (KIM-1) concentration, albumin excretion rate (AER) albumin creatinine ratio (ACR) and mRNA expression of podocin in urine in the ruthenium(II)-treaded rats. These observetions were further demonstrated by the histological analysis of the kidney, displaying improved histology of renal glomerulus in ruthenium-treated rats when compared to the PD group as seen in chapter 3 of the study. In study 3, treatment with ruthenium(II) complex resulted in reduction of platelet activation markers mean platelet volume (MPV) and CD40 Ligand (CD40 L) concentrations, which positively correlated with decreased plasma triglycerides (TG) and very low-density lipoproteins (VLDL) levels in the pre-diabetic treated rats when compared to the PD group. Whilst administration of ruthenium(II) with dietary intervention reduced plasma fibrinogen concentration in the pre-diabetic treated rats when compared to the PD group. These was further evidenced by normalization of immune cell counts in the ruthenium(II)-treated rats. Furthermore, there was a decrease in pro-inflammatory cytokines, tumor necrosis factor α (TNF-α) concentration in the ruthenium(II)-treated rats and decreased interleukin-1β (IL-1β) concentration in the ruthenium(II) with dietary interventiontreated rats when compared to the PD group as seen in chapter 4 of the study. Taken together, the results observed suggest that ruthenium(II) complex exhibited hepato and renoprotective effects while ameliorating immune dysregulation underlying pre-diabetes in diet-induced pre-diabetic rats. However, further studies are still required to find out the exact mechanism behind potential effect of this metal-based compound.
Investigating changes to the insulin signalling pathway in a diet-induced pre-diabetic rat model: effects on selected markers.
(2019) Sosibo, Aubrey Mbulelo.; Khathi, Andile.; Ngubane, Phikelelani Siphosethu.
No abstract available.
Investigating the effects of bredemolic acid on selected markers of some prediabetes-associated dysfunctions in diet-induced prediabetic rats.
(2019) Akinnuga, Akinjide Moses.; Khathi, Andile.; Sibiya, Ntethelelo Hopewell.; Ngubane, Phikelelani Siphosethu.
Prediabetes is an abnormal glycaemic state between normoglycaemia and chronic hyperglycaemia which is currently prevalent in developing and developed countries due to increased consumption of high caloric diet coupled with sedentary lifestyle. Prediabetes is associated with abnormal glucose metabolism. Additionally, the risk of developing prediabetes-associated complications such as non-alcoholic fatty liver disease (NAFLD), cardiovascular and renal diseases is not only present in overt diabetes mellitus but also in prediabetes. Management of prediabetes involves the combination of dietary and pharmacological interventions, however there is reported low compliance among patients as they tend to become overly dependent on the pharmacological interventions. Consequently, the pharmacological intervention efficacy is reduced as patients still progress to having overt diabetes. Therefore, managing prediabetes with anti-diabetic agents that will remain effective even in the absence of dietary intervention is considered necessary. Triterpenes have been found to have potential as anti-diabetic agents. Bredemolic acid (BA), a pentacyclic triterpene, has been reported to have increased biological activity relative to some other triterpenes. In this study, we sought to investigate the effects of BA on selected markers of some prediabetes-associated dysfunctions such as abnormal glucose homeostasis, hepatic, cardiovascular and renal dysfunctions in a prediabetic rat model in both the presence and absence of dietary intervention. Materials and Methods Thirty six (36) Sprague Dawley male rats that weighed 150 – 180g were divided into two groups: the non-prediabetic (n=6) and the prediabetic groups (n=30) which were fed a normal diet (ND) and high fat high carbohydrate (HFHC) diet respectively for 20 weeks to induce prediabetes. At 20th week, prediabetes was confirmed by assessment of fasting blood glucose (FBG) and oral glucose tolerance test (OGTT). The prediabetic rats were further sub-divided into five groups (n=6) and treated with either BA (80 mg/kg) or metformin (MET, 500 mg/kg) in the presence and absence of diet intervention for 12 weeks. Every 4 weeks of treatment, all the animals were placed in metabolic cages to determine caloric and fluid intake as well as urine output. Also, the body mass index (BMI), waist circumference (WC), blood pressure and heart rate were measured at every 4 weeks of treatment. After the 12 weeks of treatment, the animals were sacrificed, blood samples were collected into EDTA sample bottles and centrifuged to obtain plasma. Also, the skeletal muscle, liver, heart and kidney were collected, weighed, snapped frozen with liquid nitrogen and stored at -80°C before the biochemical analysis of selected markers of glucose homeostasis, hepatic, cardiovascular and renal functions. Results In the first study, the untreated diet-induced prediabetic rats had a significantly increased body weight, increased caloric intake, elevated glycated haemoglobin, increased ghrelin plasma concentration, decreased muscle glycogen concentration, insulin resistance and hyperinsulinaemia compared to the non-prediabetic rats. However, BA treatment with or without diet intervention ameliorated the body weight, caloric intake, glycated haemoglobin, muscle glycogen, glucose tolerance, plasma insulin and increased the expression of glucose transporter 4 (GLUT 4) in the skeletal muscle by comparison to the untreated prediabetic rats. Prediabetic induction in the second study resulted into elevated plasma concentration of liver enzymes, increased liver glycogen and triglyceride concentrations, increased oxidative stress in the liver and decreased sterol regulatory element binding protein (SREBP1c) by comparison to the non-prediabetic animals. Conversely, administration of BA with or without dietary intervention ameliorated liver functions by decreased oxidative stress, decreased liver enzymes, decreased liver glycogen and triglyceride as well as increased hepatic SREBP1c concentration in comparison to the untreated prediabetic animals. The results in the third study showed that the untreated prediabetic rats had a significantly increased body mass index (BMI), waist circumference (WC), blood pressure, heart rate, lipid profile, oxidative stress and inflammatory markers with significantly decreased endothelial nitric oxide synthase (eNOS) by comparison to the non-prediabetic control rats. On the other hand, the administration of BA with or without diet intervention improved cardiovascular functions by a decrease in BMI, WC, total cholesterol concentration, triglyceride concentration, blood pressure, heart rate, oxidative stress and inflammation with significant increase in eNOS plasma concentration in comparison to the untreated prediabetic rats. In the fourth study, the untreated prediabetic rats had a significantly increased fluid intake, urine output, sodium retention, potassium loss, aldosterone concentration, albuminuria, proteinuria, kidney injury molecule (KIM-1) and urinary podocin mRNA expression in comparison to non-prediabetic control and BA treated rats with or without diet intervention. Also, the untreated prediabetic rats presented increased albumin, total protein, urea, uric acid, creatinine and oxidative stress markers concentrations with a significant decrease in glomerular filtration rate (GFR). However, administration of BA with or without diet intervention attenuated oxidative stress, decreased urinary podocin mRNA expression and the aforementioned renal dysfunctions parameters. Conclusion This study showed that long term consumption of high caloric diet-induced prediabetes and resulted in abnormal glucose homeostasis, hepatic, cardiovascular and renal dysfunctions. Also, the results of this study showed that these dysfunctions are not only present during overt type 2 diabetes mellitus but already present at the prediabetic stage due to insulin resistance or hyperinsulinaemia that triggered oxidative stress in the physiological systems that we examined in this study. However, due to amelioration of insulin resistance via improved insulin sensitivity and earlier reported antioxidant activities that are common to all pentacyclic triterpenes, administration of BA significantly ameliorated the prediabetes-associated dysfunctions (abnormal glucose homeostasis, hepatic, cardiovascular and renal dysfunctions) with or without diet intervention in the prediabetic stage.