Effect of Acute Caffeine Exposure on Blood Glucose and Hepatic Glycogen Content in Normal and Thyroidectomized Male Wistar Rats.

Acute caffeine exposure had been shown to induce hyperglycemia however; the influence of thyroid hormones on the caffeine-induced hyperglycemia is yet to be established. The present study was therefore designed to investigate the effect of caffeine exposure on blood glucose and hepatic glycogen content in thyroidectomized rats. Sixty adult male Wistar rats were randomly divided into 10 groups as I-X (n=6).  Rats in groups I, III, V, VII and IX were given normal saline, caffeine, prazosin + caffeine, propranolol +caffeine, combined prazosin+ propranolol+caffeine injections respectively while rats in groups  II, IV, VI, VIII and X were thyroidectomized  and treated in similar manner as the normal rats respectively. Surgical removal of the thyroid gland was done in the thyroidectomised groups while sham-operation was done in Normal group to serve as control. After healing and following an overnight fast, the rats were anaesthetized and the femoral vein and carotid artery were cannulated for drug administration and blood glucose measurement respectively. After stabilization, following basal measurements, rats from each group were injected normal saline or caffeine (6mg/kg) while another sets were pre-treated prazosin (0.2 mg/kg), propanolol (0.5 mg/kg) or their combination before caffeine administration. Blood glucose was then monitored for 60 minutes post-injection of caffeine at 5 minutes interval. Liver samples were collected at the end of the observation period for glycogen content determination. Caffeine caused significant increased blood glucose levels in both normal and thyroidectomized rats which were up to 210% and 180% respectively at the peak of their responses. Liver glycogen content of the thyroidectomized rats (3.11 ± 0.20 mg/100g tissue weight) was significantly higher than the normal rats (1.91 ± 0.43 mg/100g tissue weight). These glycogen contents were significantly reduced by caffeine in both normal (0.25 ± 0.04 mg/100g tissue weight) and thyroidectomized rats (1.65 ± 0.16 mg/100g tissue weight) when compared with their controls. The caffeine effects on blood glucose and hepatic glycogen content were abolished by pretreatment with propanolol or a combination of prazosin and propanolol in both normal and thyroidectomized rats but pretreatment with prazosin caused only significant reduction in hyperglycemic response to caffeine. The findings of this study suggest that caffeine-induced hyperglycemia in both normal and thyroidectomized rats are mediated through both alpha and beta adrenoceptors.

Ocimum gratissimum enhances insulin sensitivity in male Wistar rats with dexamethasone-induced insulin resistance.

PURPOSE: The antidiabetic activities of Ocimum gratissimum (OG) leaf extract are well documented in experimental diabetes induced by beta cell destruction resulting in hypoinsulinemia. There is however paucity of data on its effect in conditions characterized by hyperinsulinemia. This study therefore investigated the effect of OG on insulin resistance induced by dexamethasone in male Wistar rats. METHOD: Twenty male Wistar rats grouped as control, normal + OG, Dex and Dex + OG were used. Control and normal + OG received normal saline while Dex and Dex + OG received dexamethasone (1 mg/kg, i.p) followed by distilled water or OG (400 mg/kg) for 10 days. Levels of fasting blood glucose (FBG), insulin, HOMA-IR, liver and muscle glycogen, hexokinase activities, hepatic HMG CoA reductase activity were obtained. Histopathology of pancreas and liver tissues was carried out using standard procedures. RESULTS: Body weight reduced significantly in the Dex and Dex + OG groups compared with the control. FBG (147.8 ± 9.93 mg/dL), insulin (2.98 ± 0.49 µIU/ml) and HOMA-IR (1.11 ± 0.22) of Dex animals were higher than the control (FBG = 89.22 ± 6.53 mg/dL; insulin = 1.70 ± 0.49 µIU/ml; HOMA-IR = 0.37 ± 0.04). These were significantly reduced in the Dex + OG (FBG = 115.31 ± 5.93 mg/dL; insulin = 1.85 ± 0.11µIU/ml; HOMA-IR = 0.53 ± 0.08) compared with Dex. Glycogen content and hexokinase activities were increased in the Dex + OG. Increased pancreatic islet size, hepatic steatosis and HMG Co A reductase activity were observed in the Dex but reduced in Dex + OG. CONCLUSION: OG promotes cellular glucose utilization and reduces hepatic fat accumulation in Wistar rats with insulin resistance induced by dexamethasone. Further study to identify the involved signal transduction will throw more light on the observed effects.

Paradoxical sleep deprivation induces oxidative stress in the submandibular glands of Wistar rats.

OBJECTIVES: Paradoxical sleep deprivation has been associated with impaired salivary secretion in rats. However, the mechanism that underlies this is not known. Therefore, this study assessed salivary and serum oxidative stress levels following paradoxical sleep deprivation in rats. METHODS: Twenty-one male Wistar rats randomly divided into three groups of seven rats each as; Control (C); partial sleep-deprived (PSD); and total sleep-deprived (TSD) were used. Malondialdehyde (MDA) concentration, Superoxide dismutase (SOD), and catalase activities were evaluated in saliva, serum, and submandibular glands after seven days of sleep deprivation. Data were expressed as mean ± standard error of the mean and analyzed using one-way ANOVA, Tukey HSD post hoc, and Pearson's correlation tests. RESULTS: Serum MDA levels were significantly higher in both the TSD and PSD groups compared to the control group whereas only the TSD group showed higher submandibular MDA levels compared to the PSD group and the control group. Submandibular SOD activity was significantly lower in both the TSD and PSD groups compared to the control group. Serum catalase activity was significantly lower in the TSD group only compared to the control group. CONCLUSIONS: These results have demonstrated for the first time that paradoxical sleep deprivation was associated with changes in the oxidant/antioxidant defense system in the submandibular salivary glands of male Wistar rats which may contribute to impairment in salivary secretion.

Intestinal Glucose Release Following Insulin-induced Hypoglycemia in Dogs: Implication of Gluconeogenesis and Glycogenolysis.

This study was designed to investigate the source of the glucose released by the small intestine during insulin-induced hypoglycaemia in dogs. Experiments were carried out on fasted, male, anaesthetized mongrel dogs divided into 3 groups (n = 5 each). Group 1 received normal saline (0.2 ml/kg) and served as the control while groups 2-3 were injected with low (5 i.u/kg) and high (8 i.u/kg) doses of insulin. The left femoral artery and vein were cannulated for arterial sampling and intravenous administration route, respectively. Through a midline laparatomy, a vein draining the upper jejunum was cannulated for Intestinal Blood Flow (IBF) measurement and jejunal venous sampling. In stabilized animals, basal measurement of IBF and levels of glucose and lactate in blood were obtained prior to the injections and monitored for 90 minutes post injection. Intestinal Glucose/Lactate Uptake was calculated as the product of IBF and arterio-venous glucose /lactate difference. Jejunal tissue samples were obtained for the determination of Glycogen Content and activities of glycogen synthase, glycogen phosphorylase 'a', hexokinase and glucose-6-phosphatase. Data are presented as Mean ± SEM and compared by student's t-test and ANOVA. Intestinal blood flow was significantly increased by insulin. Within 20 minutes post injection of insulin, glucose uptake was negative while lactate uptake increased. Glycogen content, glycogen synthase activity and hexokinase activity were significantly reduced in the insulin treated groups compared with the control while glycogen phosphorylase 'a' and   glucose-6-phosphatase activities were increased significantly. In conclusion, the glucose released during insulin-induced hypoglycemia may receive inputs from the breaking down of glycogen and synthesis of glucose within the small intestine.

Protective action of N-acetylcysteine on sperm quality in cyclophosphamide-induced testicular toxicity in male Wistar rats.

BACKGROUND: Reductions in sperm quality due to free radical formation during cancer chemotherapy are well documented, hence the need for an adjunct antioxidant treatment during chemotherapy. This study was designed to investigate the effects of N-acetylcysteine on sperm quality following cyclophosphamide exposure in male Wistar rats. METHODS: wenty male Wistar rats weighing 150-170g were randomly assigned into 4 groups of five rats each, and were orally administered distilled water (Control), Cyclophosphamide (6mg/kg), N-acetylcysteine (100mg/kg) or Cyclophosphamide + N-acetylcysteine for 21 days. Sperm count, histone-protamine replacement, chromatin integrity, testicular histomorphometry and BAX Protein expression were assessed using standard procedures. The data was presented as mean ± SEM and analyzed using students' t- test. A p<0.05 was considered significant. RESULTS: Sperm counts were significantly reduced (p<0.05) among the cyclophosphamide (69.95±7.78 x106/ml) and cyclophosphamide + N-acetylcysteine (64.78±3.52 x106/ml) treated rats, while it increased significantly (p<0.05) in the N-acetylcysteine (132.20±28.71 x106/ml) treated rats compared to the control animals (115.30±8.70x106/ml). Increased interstitial space distance, degenerated Leydig cells and impaired histone-protamine replacement observed among the cyclophosphamide-treated rats were ameliorated in the cyclophosphamide + N-acetylcysteine-treated rats. Sperm chromatin integrity, which was poor in the cyclophosphamide-treated rats, was considerably improved when compared with the Control and the N-acetylcysteine-treated rats. Bax protein expression was reduced in the cyclophosphamide (20%) and cyclophosphamide+N-acetylcysteine (20%) groups when compared with the Control (50%) and N-acetylcysteine (50%) groups. CONCLUSION: We concluded that N-acetylcysteine might improve sperm histone protamine replacement, which is one of the stage-specific effect of cyclophosphamide toxicity.

Switching to normal diet reverses kwashiorkor-induced salivary impairments via increased nitric oxide level and expression of aquaporin 5 in the submandibular glands of male Wistar rats.

Kwashiorkor, a form of malnutrition, has been shown to cause impaired salivary secretion. However, there is dearth of information on the mechanism that underlies this complication. Also, whether returning to normal diet after kwashiorkor will reverse these complications or not is yet to be discerned. Thus, this study aimed at assessing the mechanisms that underlie kwashiorkor-induced salivary impairments and to evaluate the effects of switching back to normal-diet on kwashiorkor-induced salivary impairments. Weaning rats were randomly divided into 3 groups (control group, kwashiorkor group (KG), re-fed kwashiorkor group (RKG)) of 7 rats each. The control group had standard rat chow while the KG and RKG were fed 2% protein diet for 6 weeks to induce kwashiorkor. The RKG had their diet changed to standard rat-chow for another 6 weeks. Blood and stimulated saliva samples were collected for the analysis of total protein, electrolytes, amylase, immunoglobulin A (IgA) secretion rate, leptin, and ghrelin. Tissue total protein, nitric oxide level, expressions of Na+/K+-ATPase, muscarinic (M3) receptor, and aquaporin 5 in the submandibular glands were also determined. Data were presented as means ± SEM and compared using ANOVA with Tukey's post hoc test. RKG showed improved salivary function evidenced by reduced salivary lag-time and potassium and increased flow rate, sodium, amylase, IgA secretion rate, leptin, submandibular nitric oxide level, and aquaporin 5 expression compared with KG. This study for the first time demonstrated that kwashiorkor caused significant reduction in salivary secretion through reduction of nitric oxide level and aquaporin 5 expression in submandibular salivary glands. Normal-diet re-feeding after kwashiorkor returned salivary secretion to normal.

Ocimum gratissimum leaf extract may precipitate infertility in male diabetic Wistar rats.

OBJECTIVE: This study was designed to investigate the Ocimum gratissimum (OG) effects on sperm quality and testicular cytoarchitecture in alloxan-induced diabetic rats. METHOD: Twenty male Wistar rats (150-200 g) were assigned into 4 groups (n=5) as A (control), B (OG), C (Dia) and D (Dia+OG). Groups A and B were normal animals receiving distilled water or OG (400 mg/kg), respectively while diabetes was induced by alloxan monohydrate (100 mg/kg) in groups C and D, followed by the administration of distilled water or OG, respectively for 28 days. Blood samples were obtained for fasting blood glucose (FBG) and fructosamine determination while, epididymis and testes were obtained for sperm quality assessment using computer-assisted sperm analyzer and testicular histomorphometry, respectively. Seminiferous tubule diameter and interstitial space distance were quantified in hematoxylin and eosin stained slides. Statistical analysis was done using ANOVA and student t-test at α0.05. RESULTS: Fructosamine and FBG were reduced in Dia+OG (80.11±3.80µmol/L and 132.0±8.41mg/dl, respectively) compared with Dia (139.66±4.29µmol/L and 285.6±26.69mg/dl, respectively). Sperm count was unchanged in Dia, but decreased in OG and Dia+OG; abnormal sperm cells increased in OG, Dia and Dia+OG. Mild vacuolation in the seminiferous tubule, disorganized germinal cells layer, arrested sperm maturation with empty spermatozoa in lumen, decreased seminiferous tubule diameter and increased interstitial space were found in the testes of OG, Dia and Dia+OG compared with control. CONCLUSION: Diabetes induces sperm impairments and distortions in testicular cytoarchitecture, which were aggravated by OG leaf extract in male Wistar rats.

Re-establishing normal diet following high fat-diet-induced obesity reverses the altered salivary composition in Wistar rats.

Background Obesity has been implicated in impaired salivary secretion. This study aimed at evaluating the influence of diet-induced obesity on salivary secretion and how re-feeding with normal diet would affect changes in salivary secretion associated with diet-induced obesity. Methods Weaning rats weighing 55-65 g were randomly divided into three groups (control, diet-induced obese, re-fed obese) of seven rats each. The diet-induced obese group was fed a high-fat diet for 15 weeks, whereas the re-fed obese group received normal diet for another 15 weeks following the 15 weeks of high-fat diet. After treatment, blood and stimulated saliva samples were collected for the analyses of total protein, electrolytes, amylase, Immunoglobulin A (IgA), leptin and ghrelin. Tissue total protein, nitric oxide level, expressions of Na+/K+-ATPase, muscarinic (M3) receptor and aquaporin 5 in the submandibular glands were determined. Data were presented as mean±SEM and compared using independent student t-test and ANOVA with Tukey's post-hoc test. Results Results indicated increases in the levels of salivary calcium, phosphate, bicarbonate and leptin, whereas the levels of salivary amylase and ghrelin showed reduction in the obese group compared with the control. Most of these changes were reversed in the re-fed obese group. There were no significant differences in salivary lag time, flow rate, levels of tissue total protein, nitric oxide and the relative expressions of M3 receptor, Na++/K+-ATPase and aquaporin 5 in the submandibular glands between the obese and control groups. Conclusions Diet-induced obesity lead to some changes in salivary factors which were reversed by returning to normal diet.

Aqueous leaf extract of Ocimum gratissimum improves hematological parameters in alloxan-induced diabetic rats via its antioxidant properties.

OBJECTIVE: This study was designed to investigate the effects of Ocimum gratissimum (OG) on hematological parameters and oxidative stress in diabetic rats. MATERIALS AND METHODS: Twenty-five male rats (150-200 g) were randomly grouped into five as control, normal + OG, diabetic untreated, diabetic + OG, and diabetic + glibenclamide groups. Diabetes was induced by 100 mg/kg of alloxan monohydrate in the diabetic untreated and diabetic + OG groups followed by treatment with distilled water and 400 mg/kg OG, respectively, whereas control, normal + OG, and diabetic + glibenclamide groups were treated with distilled water, 400 mg/kg OG, and 5 mg/kg glibenclamide, respectively. Body weight and fasting blood glucose level were monitored weekly. After 28 days of treatments, under anesthesia induced by 50 mg/kg sodium thiopental i.p., blood samples were obtained for hematological analysis, malondialdehyde (MDA) level determination, and superoxide dismutase (SOD) activity. Data were compared using analysis of variance and Student's t-test. RESULTS: There was a significant decrease in the fasting blood glucose of the diabetic + OG animals compared to the diabetic untreated and the initial reduction in weight observed in this group was reversed at the end of the experiments. Packed cell volume, red blood cell count, and hemoglobin concentration were significantly increased (P < 0.05) in the diabetic + OG when compared with the untreated group. The MDA concentration was significantly lowered (P < 0.01) in the diabetic + OG group when compared with diabetic untreated while SOD activity was significantly reduced in the diabetic untreated group. CONCLUSION: It was concluded that OG reverses anemia secondary to alloxan-induced diabetes mellitus in rats probably via its antioxidant activity.