Brain Of Diabetic Rats Research Articles

The role of endothelin in the cerebrovascular response following intracerebral haemorrhage: experimental studies using the endothelin antagonist SB209670

Primary intracerebral haemorrhage (ICH) is associated with considerable morbidity and mortality. Local endothelin release following ICH may contribute to the pathophysiology of perilesional ischaemia. In diabetics, endothelin release can be enhanced by hyperglycaemia and cerebrovascular dilation may be inhibited by vascular endothelial dysfunction. To examine the effects of endothelin-mediated vasoconstriction after spontaneous ICH in the normal and diabetic brain, regional cerebral blood flow (rCBF) was examined in insulin dependent BB-rats and non-diabetic BB control rats. These experiments were performed 24 h following experimental ICH in both groups of animals that were either given the endothelin antagonist SB209670 or saline. Perilesional oligaemia was similar in control and SB209670 treated diabetic rats, but SB209670 reduced perilesional oligaemia in normal rats. In brain contralateral to the experimental ICH, rCBF was increased by SB209670 in diabetic rats, but not in non-diabetic rats. These studies show that there are differences in the cerebrovascular effects of endothelin in perilesional and contralateral brain in non-diabetic and diabetic rats following ICH.

Proteolytic activity in the brain of alloxan diabetic rats: Presence of a proteolytic activator in the cerebral extract

BACKGROUND AND AIM:Diabetes mellitus is known to cause neurological disorders due to impaired glucose metabolism involving decreased utilization of glucose by the brain tissues. The mechanisms responsible for failure of glycemic regulation in type-2 diabetes leading to neurological impairment need to be thoroughly elucidated.MATERIALS AND METHODS:Type-2 diabetes was induced in albino rat models with alloxan monohydrate (40 mg/kg i.v.). Cerebral cortex and medulla oblongata were investigated 48 h after alloxan administration for the alterations in proteolytic activity.RESULTS:Diabetes caused an elevation (P < 0.001) of blood glucose and also proteolytic activity in the brain.CONCLUSION:Impaired glucose metabolism in the brain was the key factor which was responsible for the elevated (P < 0.001) proteolysis leading to brain dysfunction.

Enzymatic activities in brains of diabetic rats treated with vanadyl sulphate and sodium tungstate

The hypothesis of the present study was that diabetes mellitus might affect brain metabolism. Streptozotocin (STZ)-induced diabetic rats, treated with vanadyl sulphate (V) and sodium tungstate (T) were employed to observe the aspartate aminotransferase (AST), alanine aminotransferase (ALT) and creatine kinase (CK) activities in brain homogenates. Significant increases in AST, ALT and CK activities were found in diabetic brain homogenates against controls, suggesting increments of transamination in brain and/or increases in cell membrane permeability to these enzymes. The increase in brain CK possibly expresses alterations in energy production. The decrease in CK activity caused by V and T treatment in diabetic rats suggests that both agents tend to normalize energy consumption. It is also possible that V and T-induced hypoglycemic effects cause metabolic alterations in brain.

Effect of sesamol on diabetes-associated cognitive decline in rats

Emerging epidemiologic data indicates that diabetes is a potential predisposing factor for neuropsychiatric deficits as stroke, cerebrovascular diseases, diabetes-associated cognitive decline, depression and anxiety. Diabetes-associated cognitive decline, characterized by impaired cognitive functions and neurochemical and structural abnormalities, involves direct neuronal damage caused by intracellular glucose. The present study was designed to investigate the effect of sesamol (3,4-methylenedioxyphenol), a phenolic antioxidant and anti-inflammatory molecule, on cognitive functions, oxidative stress and inflammation in diabetic rats. Learning and memory behaviors were investigated using a spatial version of the Morris water maze test. Acetylcholinesterase activity, a marker of cholinergic dysfunction, was increased by 80% in the cerebral cortex of diabetic rats. There was 107 and 121% rise in thiobarbituric acid reactive substance levels in cerebral cortex and hippocampus of diabetic rats, respectively. Reduced glutathione levels and enzymatic activities of superoxide dismutase and catalase were decreased in both cerebral cortex and hippocampal regions of diabetic rat brain. Nitrite levels in cerebral cortex and hippocampus was increased by 138 and 109%, respectively. Serum tumor necrosis factor-alpha, a marker for inflammation, was found to increase by 1,100% in diabetic rats. Chronic treatment with sesamol (2, 4 and 8 mg/kg; p.o.) significantly and dose-dependently attenuated cognitive deficit, reduced acetylcholinesterase, oxidative stress and inflammation in diabetic rats. The results emphasize the involvement of oxidative stress and inflammation in the development of cognitive impairment in diabetic animals and point towards the therapeutic potential of sesamol in diabetes-associated cognitive decline.

Influence of blood glucose on the expression of glucose transporter proteins 1 and 3 in the brain of diabetic rats

The delivery of glucose from the blood to the brain involves its passage across the endothelial cells of the blood-brain barrier (BBB), which is mediated by the facilitative glucose transporter protein 1 (GLUT(1)), and then across the neural cell membranes, which is mediated by GLUT(3). This study aimed to evaluate the dynamic influence of hyperglycemia on the expression of these GLUTs by measuring their expression in the brain at different blood glucose levels in a rat model of diabetes. This might help to determine the proper blood glucose threshold level in the treatment of diabetic apoplexy. Diabetes mellitus was induced with streptozotocin (STZ) in 30 rats. The rats were randomly divided into 3 groups: diabetic group without blood glucose control (group DM1), diabetic rats treated with low dose insulin (group DM2), and diabetic rats treated with high dose insulin (group DM3). The mRNA and protein levels of GLUT(1) and GLUT(3) were assayed by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. Compared with normal control rats, the GLUT(1) mRNA was reduced by 46.08%, 29.80%, 19.22% (P < 0.01) in DM1, DM2, and DM3 group, respectively; and the GLUT(3) mRNA was reduced by 75.00%, 46.75%, and 17.89% (P < 0.01) in DM1, DM2, and DM3 group, respectively. The abundance of GLUT(1) and GLUT(3) proteins had negative correlation with the blood glucose level (P < 0.01). The density of microvessels in the brain of diabetic rats did not change significantly compared with normal rats. Chronic hyperglycemia downregulates GLUT(1) and GLUT(3) expression at both mRNA and protein levels in the rat brain, which is not due to the decrease of the density of microvessels. The downregulation of GLUT(1) and GLUT(3) expression might be the adaptive reaction of the body to prevent excessive glucose entering the cell that may lead to cell damage.

Curcumin attenuates diabetic encephalopathy in rats: Behavioral and biochemical evidences

Emerging epidemiological data indicates that diabetes is a potential predisposing factor for neuropsychiatric deficits as stroke, cerebrovascular diseases, diabetic encephalopathy, depression and anxiety. Diabetic encephalopathy, characterized by impaired cognitive functions and neurochemical and structural abnormalities, involves direct neuronal damage caused by intracellular glucose. Curcumin, a well-established phenolic antioxidant and anti-inflammatory molecule, is capable of playing an important role against amyloid and dendritic pathology and thus has neuroprotective properties. The aim of the present study was to explore the effect of curcumin (60 mg/kg; p.o.) on cognitive functions, oxidative stress and inflammation in diabetic rats. Learning and memory behaviors were investigated using a spatial version of the Morris water maze test. Acetylcholinesterase activity, a marker of cholinergic dysfunction, was increased by 80% in the cerebral cortex of diabetic rats. There was 107% and 121% rise in thiobarbituric acid reactive substance levels in cerebral cortex and hippocampus of diabetic rats, respectively. Reduced glutathione level and enzymatic activities of superoxide dismutase and catalase were decreased in both cerebral cortex and hippocampal regions of diabetic rat brain. Nitrite levels in cerebral cortex and hippocampus were increased by 112% and 94% respectively. Serum TNF-α, a marker for inflammation, was found to increase by 1100% in diabetic rats. Chronic treatment with curcumin (60 mg/kg; p.o.) significantly attenuated cognitive deficit, cholinergic dysfunction, oxidative stress and inflammation in diabetic rats. The results emphasize the involvement of cholinergic dysfunction, oxidative stress and inflammation in the development of cognitive impairment in diabetic animals and point towards the potential of curcumin as an adjuvant therapy to conventional anti-hyperglycemic regimens for the prevention and treatment of diabetic encephalopathy.

Disturbance of transduction of adenylyl cyclase-inhibiting hormonal signaling in the myocardium and brain of rats with experimental type 2 diabetes

Presently, our work, as well as that of other authors, has produced convincing evidence in favor of the idea that disturbances in hormonal signaling systems are one of the main causes of the development of pathological alterations and complications in diabetes. However, the molecular mechanisms underlying these disturbances remain practically unstudied, particularly in insulin-independent type 2 diabetes. Using a neonatal streptozotocin model of type 2 diabetes, whose duration was either 80 or 180 days, we studied changes in the functional activity of components of the hormone-regulated adenylyl cyclase (AC) signaling system in the myocardium and brain striatum of diabetic rats as compared with control animals. In diabetes, the Gi-realized process of transduction of the hormonal signal inhibiting AC activity has been shown to be markedly impaired. This is manifested as a decrease of the inhibitory effect of hormones on AC activity and an attenuation of their stimulation of the G-protein’s GTP-binding activity. In the case of noradrenaline (myocardium), the inhibitory pathway of the AC system regulation is completely suppressed, while the stimulatory pathway is preserved. An increase in the duration of diabetes development from 80 to 180 days leads to some decrease in the transduction of hormonal signals realized via Gi-proteins. The stimulatory effects of biogenic amines and relaxin on AC activity and GTP binding in the myocardium and brain of diabetic rats change relatively little, both in the 80-and in the 180-day diabetes. Thus, in the experimental type 2 diabetes, disturbances in Gi-protein coupled signal cascades are primarily observed, through which hormones realize their inhibition of AC activity.

Functional Induction of P-glycoprotein in the Blood-Brain Barrier of Streptozotocin-Induced Diabetic Rats: Evidence for the Involvement of Nuclear Factor-κB, a Nitrosative Stress-Sensitive Transcription Factor, in the Regulation

The objective of this study was to investigate the transport kinetics of cyclosporin A, a well known substrate for P-glycoprotein (P-gp), across the blood-brain barrier (BBB), and the expression of the transporter in the brain of streptozotocin-induced diabetic rats. The in vivo transport clearance of cyclosporin A was significantly reduced in diabetic rats compared with that in the control. The decreased transport was associated with the increased level of mRNA and the protein for P-glycoprotein in the rat brain. The functional activity of the efflux transporter in mouse brain capillary endothelial (MBEC4) cells, an in vitro model of the BBB, was also stimulated when slow nitric oxide (NO)-releasing donors were present, whereas the stimulation was absent in the case of rapid NO-releasing donors (e.g., S-nitroso-N-acetyl-dl-penicillamine and diethylenetriamine). The stimulatory effect was highest for sodium nitroprusside (SNP) and the functional induction associated with the increased mRNA and protein level of the transporter. The pretreatment of the cell with SNP along with ascorbate, methylene blue, or superoxide dismutase attenuated the induction of function and expression for P-glycoprotein, suggesting that the reaction product between superoxide and NO is involved in the induction of function and expression. The level of nuclear translocation of nuclear factor-kappaB (NF-kappaB) and DNA binding activity of nuclear extracts to the NF-kappaB consensus oligonucleotide was increased in MBEC4 cells pretreated with SNP. Taken together, these observations suggest that nitrosative stress leads to the up-regulation of the message for the efflux transporter and, ultimately, to the enhanced function, probably via a NF-kappaB-dependent mechanism.

Reduced Brain Antioxidant Capacity in Rat Models of Betacytotoxic-Induced Experimental Sporadic Alzheimer’s Disease and Diabetes Mellitus

It is believed that oxidative stress (OS) plays a central role in the pathogenesis of metabolic diseases like diabetes mellitus (DM) and its complications (like peripheral neuropathy) as well as in neurodegenerative disorders like sporadic Alzheimer's disease (sAD). Representative experimental models of these diseases are streptozotocin (STZ)-induced diabetic rats and STZ-intracerebroventricularly (STZ-icv) treated rats, in which antioxidant capacity (AC) against peroxyl (ORAC(-ROO) (*)) and hydroxyl (ORAC(-OH) (*)) free radicals (FR) was measured in three different brain regions: the hippocampus (HPC), the cerebellum (CB), and the brain stem (BS) by means of oxygen radical absorbance capacity (ORAC) assay. In the brain of both STZ-induced diabetic and STZ-icv treated rats decreased AC has been found demonstrating regionally specific distribution. In the diabetic rats these abnormalities were not associated with the development of peripheral diabetic neuropathy (PDN). Also, these abnormalities were not prevented by the intracerebroventricularly (icv) pretreatment of glucose transport inhibitor 5-thio-D: -glucose (TG) in the STZ-icv treated rats, suggesting different mechanism of STZ-induced central effects from those at the periphery. Similarities of the OS alterations in the brain of STZ-icv rats and humans with sAD could be useful in the search for the new drugs in the treatment of sAD that have antioxidant activity. In the STZ-induced diabetic animals the existence of PDN was tested by the paw pressure test, 3 weeks following the diabetes induction. Mechanical nociceptive thresholds were measured three times at 10-min intervals by applying increased pressure to the hind paw until the paw-withdrawal or overt struggling was elicited. Only those diabetic animals which demonstrated decreased withdrawal threshold values in comparison with the control non-diabetic animals (C) were considered to have developed the PDN.

Tetrahydrocurcumin Prevents Brain Lipid Peroxidation in Streptozotocin-Induced Diabetic Rats

Oxidative damage has been suggested to be a contributory factor in the development and complication of diabetes. To investigate the effect of tetrahydrocurcumin (THC) on the occurrence of oxidative stress in the brain of rats during diabetes, we investigated the extent of oxidative damage as well as the status of the antioxidant defense system. Oral administration of THC at 80 mg/kg of body weight to diabetic rats for 45 days resulted in a significant reduction in blood glucose and significant increase in plasma insulin levels. In addition, THC caused significant increases in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, and reduced glutathione in the brains of diabetic rats with significant decrease in the lipid peroxidative markers thiobarbituric acid-reactive substances and hydroperoxides in brain, suggesting efficacy for protection against lipid peroxidation-induced membrane damage. The effect of THC was greater than that of curcumin. Results of the present study suggest that THC showed antioxidant effects in addition to its antidiabetic effect in type 2 diabetic rats.

Monitoring of choline level in diabetic rat's brain during post-opioids administration by multienzyme sensors

The influence of opioids towards the level of choline (Ch) in hippocampus and striatum is still unknown. However, past studies have contradicted reporting on the levels of Ch in these regions of brain. In the present study, the levels of Ch in these two regions of the brain were monitored by implanting a Ch microsensor prior to opioids administration. The microsensors, operated at an applied potential of +0.10 V versus Ag/AgCl, registered choline concentration directly via redox processes at the surface of the microsensor. Results at post-opioids administration showed an increase in Ch level in hippocampus region but not in striatum region. The finding suggested that the administration of opioids have not only increased cellular Ch levels by either synthesis or release of Ch but by other cellular pathway as well.

Streptozotocin-induced diabetes is associated with changes in NGF levels in pancreas and brain.

Type 1 diabetes mellitus (DM), a "classical" result of a pancreatic-beta cell damage, is associated with various metabolic, neuronal, endocrine and immune alterations at cellular, tissue and organ levels. Nerve growth factor (NGF) is one of the most extensively studied neurotrophic factors, which is produced and released by numerous cells including the pancreatic beta cells. NGF plays an important role during brain development and may be able to delay or even reverse damaged forebrain cholinergic neurons that undergo degeneration in aged animals and in Alzheimer's disease (AD). Recent reports indicate that experimentally induced DM in rodents can cause brain biochemical and molecular alterations similar to those observed in sporadic AD. Given the importance of NGF in the pathophysiology of brain cholinergic neurons, we looked for NGF changes in the pancreas and brain of diabetic rats. The aim of this study was, therefore, to investigate the effect of streptozotocin-induced DM on NGF and NGF receptor expression in pancreas and brain. The results showed that DM is associated with altered NGF, NGF-receptor expression in both pancreas and brain.

Alterations in mRNA Expression of Myelin Proteins in the Sciatic Nerves and Brains of Streptozotocin-induced Diabetic Rats

Diabetic neuropathy is the most common complication of diabetes. We examined the levels and the mRNA expression of myelin proteins in the sciatic nerves and the brains of streptozotocin-induced diabetic rats. The diabetic rats exhibited a decrease in body weight, elevation of the blood glucose level and a decrease in motor nerve conduction velocity at 2 weeks after streptozotocin injection. In the sciatic nerves of diabetic rats, the level of P0 protein and its mRNA expression were markedly reduced at 20 weeks after the injection. In the brains, the levels of proteolipid protein and myelin-associated glycoprotein and their mRNA expression were selectively decreased at 20 weeks after the injection. This affected expression of myelin proteins was found even when no histological abnormalities were detectable. Considering the functional significance of myelin proteins, this impairment of protein expression is possibly involved in the pathogenesis of diabetic neuropathy, including that in brain disorders.

Toxicity of diazinon and its metabolites increases in diabetic rats

The effect of diazinon (DZN) on the activities of cholinesterase (ChE) in plasma and acetylcholinesterase (AChE) in erythrocyte and brain was investigated in normal and streptozotocin-induced diabetic rats. Hepatic drug-metabolizing enzyme activity was also estimated by measuring the systemic clearance of antipyrine, and the expression of hepatic cytochrome P450 (CYP) 3A2 and CYP1A2, which is closely related to the metabolism from DZN to DZN-oxon, a strong inhibitor of both ChE and AChE. No significant differences in the activities of ChE in plasma and AChE in erythrocyte were observed between normal and diabetic rats. Treatment with DZN significantly decreased these activities in diabetic rats more than in normal rats 6 h after injection (6.5 mg/kg). Treatment with DZN significantly decreased the activity of AChE in brain of diabetic rats than normal rats 3 h after injection (65 mg/kg), although no significant difference in the activity was found between normal and diabetic rats. The urinary recovery of diethylphosphate (DEP), a metabolite of DZN-oxon, was significantly increased in diabetic rats, but that of diethylthiophosphate (DETP), a metabolite of DZN, was unchanged. Significant increases in the systemic clearance of antipyrine and protein levels of hepatic CYP1A2, not CYP3A2, were observed in diabetic rats. These results suggest the possibility that a metabolite of DZN, DZN-oxon, causes higher toxicity in diabetic rats due to the enhancement of hepatic CYP1A2-mediated metabolism of DZN.

Differential effect of insulin treatment on decreased levels of beta-defensins and Toll-like receptors in diabetic rats

Many infections are associated with diabetes, as the ability of the body to fight pathogens is impaired. Recently, altered levels of defensins and polymorphism in Toll-like receptors (TLRs), two crucial components of the innate immune system, have been associated with diabetes. To study the functionality of the innate immune system during diabetes, we measured the expression levels of rat beta-defensin 1 (rBD-1), rBD-2, rTLR2, and rTLR4 in the kidney, lung, liver, and brain of streptozotocin-induced diabetic rats with and without insulin treatment. In the kidneys of diabetic rats, lower levels of rBD-1, rTLR2, and rTLR4 were found. These low levels could be restored with insulin treatment. In contrast, rBD-2 was highly induced in the lungs of diabetic rats, most likely, as a result of a pro-inflammatory response. In the liver and brain of diabetic rats, lower levels of TLRs and/or defensins could not be restored with insulin treatment. Our findings suggest for the first time that high blood glucose and/or insulin deficiency abrogates the expression level of the innate immune system components, defensins and TLRs, explaining the recurrent infections during diabetes. These findings may lay the grounds for future design of novel treatments that will induce defensins and TLRs and, as a result, bolster the immune system in diabetic patients.

Ameliorative effects of dietary caloric restriction on oxidative stress and inflammation in the brain of streptozotocin-induced diabetic rats

Background There is a strong association between oxidative stress and inflammation in the pathologies of diabetes. Recent evidence suggests that these phenomena could impair brain function. We investigated the potential role of dietary caloric restriction in ameliorating the effects of both oxidative stress and inflammation in the brain of streptozotocin-induced type 2 diabetic rats. Methods Forty male Wistar rats were subjected to 30% caloric restriction (20 animals) and ad libitum feeding (20 animals) for 9 weeks before the induction of diabetes in 20 animals (10 from each group) by intraperitoneal injection of 35 mg/kg body weight streptozotocin. Results Caloric restriction was able to significantly ( p > 0.05) reduce triglyceride, ROS, IL6, TNF-α and body weights in diabetic rats. However, no significant differences were obtained in the antioxidant enzyme (SOD, CAT and GPx) activities except in GPx where caloric restriction increased the levels in both non-diabetic and diabetic rats. Conclusion Caloric restriction was found to ameliorate the oxidative and inflammatory effects of diabetes in the brain. Non-diabetic rats feeding ad libitum were found to have increased levels of oxidative stress and inflammatory biomarkers and these could, in part, be due to their increased body weights.

Up-Regulation of Advanced Glycated Products Receptors in the Brain of Diabetic Rats Is Prevented by Antioxidant Treatment

Diabetics have at least twice the risk of stroke and may show performance deficit in a wide range of cognitive domains. The mechanisms underlying this gradually developing end-organ damage may involve both vascular changes and direct damage to neuronal cells as a result of overproduction of superoxide by the respiratory chain and consequent oxidative stress. The study aimed to assess the role of oxidative stress on the aldose reductase-polyol pathway, on advanced glycated end-product (AGE)/AGE-receptor interaction, and on downstream signaling in the hippocampus of streptozotocin-treated rats. Data show that, in diabetic rats, levels of prooxidant compounds increase, whereas levels of antioxidant compounds fall. Receptor for AGE and galectin-3 content and polyol flux increase, whereas glyceraldehyde-3-phosphate dehydrogenase activity is impaired. Moreover, nuclear factor kappaB (p65) transcription factor levels and S-100 protein are increased in the hippocampus cytosol, suggesting that oxidative stress triggers the cascade of events that finally leads to neuronal damage. Dehydroepiandrosterone, the most abundant hormonal steroid in the blood, has been reported to possess antioxidant properties. When dehydroepiandrosterone was administered to diabetic rats, the improved oxidative imbalance and the marked reduction of AGE receptors paralleled the reduced activation of nuclear factor kappaB and the reduction of S-100 levels, reinforcing the suggestion that oxidative stress plays a role in diabetes-related neuronal damage.

Amelioration of altered antioxidant status and membrane linked functions by vanadium andTrigonella in alloxan diabetic rat brains

Trigonella foenum graecum seed powder (TSP) and sodium orthovanadate (SOV) have been reported to have antidiabetic effects. However, SOV exerts hypoglycemic effects at relatively high doses with several toxic effects. We used low doses of vanadate in combination with TSP and evaluated their antidiabetic effects on anti-oxidant enzymes and membrane-linked functions in diabetic rat brains. In rats, diabetes was induced by alloxan monohydrate (15 mg/100 g body wt.) and they were treated with 2 IU insulin, 0.6 mg/ml SOV, 5% TSP and a combination of 0.2 mg/ml SOV with 5% TSP for 21 days. Blood glucose levels, activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), Na+/K+ ATPase, membrane lipid peroxidation and fluidity were determined in different fractions of whole brain after 21 days of treatment. Diabetic rats showed high blood glucose (P less than 0.001), decreased activities of SOD, catalase and Na+/K+ ATPase (P less than 0.01, P less than 0.001 and P less than 0.01), increased levels of GPx and MDA (P less than 0.01 and P less than 0.001) and decreased membrane fluidity (P less than 0.01). Treatment with different antidiabetic compounds restored the above-altered parameters. Combined dose of Trigonella and vanadate was found to be the most effective treatment in normalizing these alterations. Lower doses of vanadate could be used in combination with TSP to effectively counter diabetic alterations without any toxic effects.

Effects of triple antioxidant combination (vitamin E, vitamin C and α-lipoic acid) with insulin on lipid and cholesterol levels and fatty acid composition of brain tissue in experimental diabetic and non-diabetic rats

The aim of this research was to examine the effects of a triple antioxidant combination (vitamins E (VE) and C (VC) plus alpha-lipoic acid (LA)) on the total lipid and cholesterol levels and the fatty acid composition of brain tissues in experimental diabetic and non-diabetic rats. VE and LA were injected intraperitoneally (50 mg/kg) four times per week and VC was provided as a supplement dissolved in the drinking water (50 mg/kg). In addition, rats in the diabetes 1 and D+VELAVC groups were given daily by subcutaneous insulin injections (8 IU/kg), but no insulin was given to rats in the diabetes 2 group. The results indicate that the brain lipid levels in the D+VELAVC, diabetes 1 and diabetes 2 groups were higher than in the control group (P<0.01). Total lipid was also higher in the non-diabetic rats treated with LA and VC. Total cholesterol was higher in the diabetes 1 and diabetes 2 groups (P<0.05) than in controls. Cholesterol levels were similar in the D+VELAVC and LA groups but lower in the VC, VE and VELAVC groups of non-diabetic rats (P<0.05 and P<0.01). In respect of fatty acid composition, palmitic acid levels were lower in the diabetes 2 and non-diabetic VE groups than the control group (P<0.05), but higher in the non-diabetic LA group (P<0.05). Oleic acid (18:1 n-9) levels were lower in the diabetic and non-diabetic groups than the control group (P<0.01), but higher in the non-diabetic LA group. Arachidonic acid (20:4 n-6) levels were similar in the diabetes 1, D+VELAVC and control groups (P>0.05) but higher in the non-diabetic VE, VC, LA and VEVCLA groups (P<0.05) and lower in the diabetes 2 group (P<0.05). Docosahexaenoic acid (22:6 n-3) was elevated in the diabetes 2 and VEVCLA groups (P<0.01, P<0.05). In conclusion, the current study confirmed that treatment with a triple combination of VE, VC and LA protects the arachidonic acid level in the brains of diabetic and non-diabetic rats.

Novel role for gabapentin in neuroprotection of central nervous system in streptozotocine-induced diabetic rats1

To investigate the effect of gabapentin on neural [neuron-specific enolase (NSE)] and glial markers [glial fibrillary acidic protein (GFAP) and S100B] in different brain regions of diabetic rats. Diabetes was induced by a single intraperitoneal injection of streptozotocine (50 mg/kg body weight). Rats in one diabetic group received gabapentin (50 mg.kg(-1).d(-1)) and rats in the other diabetic group received vehicle only for 6 weeks. The levels of GFAP, S100B, and NSE were determined by immunoblotting in the hippocampus, cortex, and cerebellum. Lipid peroxidation (LPO as malondialdehyde+ 4-hydroxyalkenals) and glutathione (GSH) levels were also determined in the same brain parts. Total and degraded GFAP content and S100B protein expression in different areas of brain tissues significantly increased in diabetic rats compared to control rats. Similarly, NSE levels were also significantly elevated in hyperglycemic rats. In addition, there was a significant increase in LPO levels in the diabetic rat brain compared to control rat brains. Pretreatment with gabapentin prevented the upregulation of GFAP, S100B, and NSE in all brain regions of diabetic rats. The level of LPO was reduced, but not completely halted, by treatment with gabapentin. These results suggest that diabetes causes glial and neuronal injury, possibly as a result of elevated oxidative stress, and that gabapentin protects neurons and glial cells. Thus, we predict that gabapentin treatment will attenuate the hippo-campal and cortical neurodegeneration observed during diabetes mellitus in rats.