Yogendra Kumar Gupta

Protective effect of resveratrol against oxidative stress in middle cerebral artery occlusion model of stroke in rats.

Free radicals have been implicated in neuronal injury during ischemia reperfusion in stroke. Trans resveratrol, a potent antioxidant, polyphenolic compound found in grapes and wines has recently been shown to have neuroprotective activity against oxidative stress in in vitro studies. In the present study the effect of chronic treatment of trans resveratrol was evaluated in focal ischemia induced by middle cerebral artery [MCA] occlusion in rats. Male Wistar rats were pretreated with trans resveratrol 20 mg/kg i.p. for 21 days and were subjected to focal ischemia by occlusion of MCA using intraluminal thread. After two hours of MCA occlusion reperfusion was allowed by retracting the thread. Animals were assessed for motor performance after 24 hours and subsequently rats were sacrificed for estimation of markers of oxidative stress [malondialdehyde [MDA] and reduced glutathione] and for evaluation of volume of infarction. Control group received vehicle and similar protocol was followed. Significant motor impairment, with elevated levels of MDA and reduced glutathione was observed in the vehicle treated MCA occluded rats. Treatment with trans resveratrol prevented motor impairment, rise in levels of MDA and reduced glutathione and also significantly decreased the volume of infarct as compared to control. The study provides first evidence of effectiveness of trans resveratrol in focal ischemia most probably by virtue of its antioxidant property.

Chronic treatment with trans resveratrol prevents intracerebroventricular streptozotocin induced cognitive impairment and oxidative stress in rats.

We have recently shown free radical generation is associated with cognitive impairment in intracerebroventricular (ICV) streptozotocin (STZ) model of sporadic dementia of Alzheimers type in rats. Trans resveratrol is a polyphenolic compound and is known to have antioxidant activity. In the present study, the effect of trans resveratrol was investigated on ICV STZ induced cognitive impairment and oxidative stress in rats. Adult male Wistar rats were injected with ICV STZ bilaterally, on day 1 and day 3. The learning and memory behavior was assessed using passive avoidance paradigms, elevated plus maze and the closed field activity test while the parameters of oxidative stress assessed were malondialdehyde [MDA] and glutathione. The rats were treated with trans resveratrol chronically at doses of 10 and 20 mg/kg,i.p. for 21 days starting from day 1 of STZ injection. Trans resveratrol treatment significantly prevented ICV STZ induced cognitive impairment. There was a rise in brain glutathione and an insignificant increase in brain MDA in trans resveratrol treated ICV STZ rats as compared to significantly elevated brain MDA levels in the vehicle treated ICV STZ animals. The study demonstrates the effectiveness of trans resveratrol in preventing the cognitive deficits as well as the oxidative stress caused by ICV STZ in rats and its potential in the treatment of neurodegenerative diseases such as Alzheimers disease.

Intracerebroventricular injection of streptozotocin in rats produces both oxidative stress in the brain and cognitive impairment.

Recent reports suggest the involvement of free radicals in the pathophysiology of Alzheimers disease [AD]. Streptozotocin [STZ] injection in the brain is known to cause cognitive impairment in rats and is likened to sporadic AD in humans. Though STZ is known to cause impairment in glucose and energy metabolism, it is not known whether this is associated with free radical generation. The present study was designed to investigate if the changes in learning and memory by intracerebroventricular administration of STZ are associated with changes in the markers of oxidative stress. Adult male Wistar rats [330-340 g] were injected with intracerebroventricular STZ [3 mg/kg] bilaterally stereotaxically under ketamine anesthesia [70 mg/kg]. The rats were treated with STZ twice, on day 1 and on day 3. The learning and memory behavior was analyzed using passive avoidance paradigms, elevated plus maze and the closed field activity test while the parameters of oxidative stress assessed were malondialdehyde [MDA] and glutathione. The behavioral tests were performed on day 17, 18 and 19. The rats developed significant deficits in learning, memory and cognitive behavior, indicated by deficits in passive avoidance paradigm and elevated plus maze as compared to sham rats. On day 21, the rats were sacrificed under ether anesthesia and the brains were analyzed for biochemical studies. There was a development of oxidative stress in the brain as indicated by significant elevations in malondialdehyde [MDA] levels and decreased levels of glutathione. The study demonstrates that intracerebroventricular STZ may be appropriate model for investigations of antioxidants as potential treatment in Alzheimers dementia.

Protective effect of trans-resveratrol against kainic acid-induced seizures and oxidative stress in rats

Overexcitation of excitatory amino acid is an important mechanism in seizure genesis wherein free radicals have recently been suggested to play a critical role. Thus, intervention by antioxidants can be a potential beneficial approach in the treatment of epilepsy. The present study was undertaken to see the effect of trans-resveratrol, a potent antioxidant, against kainic acid-induced seizures, and effect on markers of oxidative stress in brain. Kainic acid, 10 mg/kg ip, induced long-lasting seizures and associated symptoms. The brain level of malondialdehyde (MDA) was found to be significantly raised after kainic acid administration (295 +/- 18 nmol/g wet tissue) as compared to control (195 +/- 26 nmol/g wet tissue). Pretreatment (5 min) of single dose of trans-resveratrol (40 mg/kg i.p.) could not inhibit the convulsions though the latency was significantly increased. When multiple doses of trans-resveratrol were injected in two-dose schedules in different animals (20 and 40 mg/kg ip, 5 min prior and repeated 30 and 90 min after kainic acid), there was significant reduction in incidence of convulsions in both treatment schedules. The brain MDA levels were found to be significantly attenuated in the trans-resveratrol-treated groups (multiple doses of 20 and 40 mg/kg) as compared to the kainic acid alone. However, the glutathione level in control, kainic acid- and trans-resveratrol-treated animals were not significantly different. The protective effect of trans-resveratrol against kainic acid-induced convulsions and the attenuation of raised MDA level suggest the potential use of antioxidants at least as adjunct therapy in epilepsy.

Effect of adenosine receptor modulation on pentylenetetrazole-induced seizures in rats

The effects of adenosine, the adenosine analogue, 2‐chloroadenosine (2‐CADO), the specific adenosine A1 receptor agonist, N6‐cyclopentyladenosine (CPA) and A2 receptor agonist 5′‐(N‐cyclopropyl) carboxamidoadenosine (CPCA), were examined against seizures induced by acute administration of pentylenetetrazole (PTZ), 60 mg kg−1, and PTZ kindled seizures, in rats. Adenosine 1000 mg kg−1, i.p., 5 min pretreatment and CPA 10 mg kg−1 i.p., 60 min pretreatment, showed significant protection against acute PTZ‐induced seizures while, CPCA up to 10 mg kg−1 was ineffective. The adenosine analogue 2‐CADO in a dose of 5 mg kg−1 was only partially protective and on increasing the dose to 10 mg kg−1, this protection was lost. Theophylline, a non specific adenosine receptor antagonist at 50 mg kg−1 and the specific adenosine A1 receptor antagonist, 8‐cyclopentyl‐1,3‐dipropylxanthine (DPCPX), at 1 mg kg−1, if administered before the maximally protective doses of adenosine and CPA, completely reversed the protection afforded by them against PTZ seizures. While, pretreatment with the adenosine A2 receptor antagonist, 3,7‐dimethyl‐1‐propargylxanthine (DMPX), failed to reverse the protection. Adenosine and the adenosine A1 receptor agonist in doses that protected against seizures after acute PTZ administration, offered only incomplete protection when tested against PTZ kindled seizures. The effects of adenosine and adenosine receptor agonists on mean arterial pressure, heart rate and rectal temperature were studied, to rule out the possibility of their systemic effects mediating the protection of PTZ seizures. All these agents produced a fall in mean arterial pressure, heart rate and hypothermia in the doses exhibiting an anticonvulsant response. While the effect on blood pressure and heart rate was immediate i.e. seen within 5 min and, maintained throughout the observation period, the development of hypothermia lagged behind the onset of hypotension and bradycardia. However, there was no correlation between haemodynamic and hypothermic response and the anticonvulsant effect. The results indicate that the adenosine mediated anticonvulsant effect is via stimulation of A1 receptors. Hypotension and hypothermia do not appear to contribute to the protection observed with adenosine and the adenosine A1 receptor agonists.

Reversal of cisplatin-induced delay in gastric emptying in rats by ginger (Zingiber officinale).

Cisplatin causes nausea, vomiting and inhibition of gastric emptying. We have demonstrated the antiemetic effect of the acetone and ethanolic extract of ginger (Zingiber officinale, Roscoe, Zingiberacae) against cisplatin-induced emesis in dogs. In the present study, the acetone and 50% ethanolic extract of ginger in the doses of 100, 200 and 500 mg/kg (p.o.) and ginger juice, in the doses of 2 and 4 ml/kg, were investigated against cisplatin effect on gastric emptying in rats. All three ginger preparations significantly reversed cisplatin-induced delay in gastric emptying. The ginger juice and acetone extract were more effective than the 50% ethanolic extract. The reversal produced by the ginger acetone extract was similar to that caused by the 5-HT3 receptor antagonist ondansetron; however, ginger juice produced better reversal than ondansetron. Therefore, ginger, an antiemetic for cancer chemotherapy, may also be useful in improving the gastrointestinal side effects of cancer chemotherapy.

Protective effect of curcumin against seizures and cognitive impairment in a pentylenetetrazole-kindled epileptic rat model

AIM Epilepsy as well as chronic use of most antiepileptic drugs predisposes to cognitive impairment. Curcumin has been reported to possess antioxidant, anticonvulsant as well as neuroprotective potential. Hence, this study was conducted to evaluate the effect of curcumin against seizures, cognitive impairment and oxidative stress in pentylenetetrazole-induced kindling in rats. MAIN METHODS The effect of pretreatment with curcumin (100, 200 and 300 mg/kg, orally) on pentylenetetrazole (PTZ)-induced kindling, kindling-induced cognitive impairment and oxidative stress was evaluated. Male Wistar rats were injected PTZ (30 mg/kg, i.p.) once every alternate day (48±1h) until the development of kindling. Cognitive impairment was assessed using elevated plus maze and passive avoidance test while the oxidative stress parameters (malondialdehyde and glutathione) were estimated in the whole brain at the end of experiments. KEY FINDINGS PTZ, 30 mg/kg, induced kindling in rats after 31.0±1.4 days. Curcumin showed dose-dependent anti-seizure effect. Curcumin (300 mg/kg) significantly increased the latency to myoclonic jerks, clonic seizures as well as generalized tonic-clonic seizures, improved the seizure score and decreased the number of myoclonic jerks. PTZ kindling induced a significant oxidative stress and cognitive impairment which was reversed by pretreatment with curcumin in a dose-dependent manner. SIGNIFICANCE The results indicate that pretreatment with curcumin ameliorates seizures, oxidative stress and cognitive impairment in PTZ induced kindling in rats. These results thus suggest the potential of curcumin as an adjuvant in epilepsy both to prevent seizures as well as to protect against seizure induced memory impairment.

Antiemetic efficacy of ginger (Zingiber officinale) against cisplatin-induced emesis in dogs

Effect of ginger (Zingiber officinale Roscoe, Zingiberaceae) extracts (acetone, 50% ethanolic and aqueous) were investigated for antiemetic activity against emesis induced by 3 mg/kg cisplatin (the 100% emetic dose i.v.) in-healthy mongrel dogs. The acetone and 50% ethanolic extract at the doses of 25, 50, 100 and 200 mg/kg p.o. exhibited significant protection while aqueous extract at these doses was ineffective against cisplatin emesis. The acetone extract was more effective than ethanolic extract. However, both were less effective when compared to 5-HT3 receptors antagonist-granisetron. Neither of the ginger extract was effective against apomorphine-induced emesis. The findings suggest that ginger could be an effective and cheap antiemetic adjunct to cancer chemotherapy.

Effect of chronic treatment of melatonin on learning, memory and oxidative deficiencies induced by intracerebroventricular streptozotocin in rats

Intracerebroventricular (ICV) streptozotocin (STZ) has been shown to cause cognitive impairment, which is associated with free radical generation in the brain of rats. Melatonin is a potent free radical scavenger and antioxidant. In the present study, the effect of melatonin was investigated against ICV STZ induced cognitive impairment and oxidative stress in rats. Adult male Wistar rats were injected with ICV STZ (3 mg/kg) bilaterally. The rats were treated with STZ twice, on days 1 and 3. The learning and memory behavior was assessed using passive avoidance paradigms, elevated plus maze and the closed field activity while the parameters of oxidative stress assessed were malondialdehyde (MDA) and glutathione. The rats were treated chronically with melatonin for 21 days starting from day 1 of STZ injection. The learning and memory behavior was evaluated on days 17, 18 and 19 and the rats were sacrificed on day 21 for estimation of MDA and glutathione. The rats treated with melatonin showed significantly less cognitive impairment. There was also insignificant increase in brain MDA and decrease in glutathione levels in melatonin-treated ICV STZ rats as compared to the vehicle-treated ICV STZ animals. The study demonstrates the effectiveness of melatonin in preventing the cognitive deficits as well as the oxidative stress caused by ICV STZ in rats and suggests its potential in age and age-related neurodegenerative disorders where oxidative stress and cognitive impairment are involved.

Effect of melatonin on ischemia reperfusion injury induced by middle cerebral artery occlusion in rats.

Free radicals have been implicated in neuronal injury during ischemia reperfusion in stroke. Therefore, in the present study, melatonin, a potent antioxidant, was studied in male Wistar rats subjected to 2 h of transient middle cerebral artery occlusion. Melatonin (10, 20 and 40 mg/kg i.p.) was administered four times in an animal at the time of middle cerebral artery occlusion, 1 h after middle cerebral artery occlusion, at the time of reperfusion and 1 h after reperfusion. Two hours after reperfusion, rats were euthanized for estimation of oxidative stress markers (malondialdehyde and reduced glutathione). The doses of 20 and 40 mg/kg of melatonin significantly attenuated the raised level of malondialdehyde (287+/-28, 279+/-52 nmol/g wet tissue, respectively) as compared to the levels (420+/-61 nmol/g wet tissue) in vehicle-treated middle cerebral artery-occluded rats. There was an insignificant change in levels of reduced glutathione at these doses (95+/-42, 88.7+/-36 microg/g wet tissue, respectively) as compared to those in the vehicle-treated middle cerebral artery-occluded rats (108.21+/-21 microg/g wet tissue). However, there was an insignificant difference between 20 and 40 mg/kg treated rats. Therefore, the dose of 20 mg/kg i.p. was used to evaluate the neuroprotective effect by using diffusion-weighted imaging (30 min after reperfusion), assessing the neurological deficit (24 h after middle cerebral artery occlusion) and estimating oxidative stress markers (72 h after middle cerebral artery occlusion). In the 20 mg/kg melatonin-treated group, percent ischemic lesion volume on diffusion-weighted imaging was significantly attenuated (9.8+/-3.9) as compared to that in the vehicle-treated group (21.4+/-4.7). The neurological deficit was significantly improved in the melatonin group (1.8+/-0.06) as compared to that in the vehicle-treated (2.9+/-0.38) group. The level of malondialdehyde (321.4+/-31 nmol/g wet tissue) and reduced glutathione (142.6+/-13 microg/g wet tissue) in the melatonin-treated group was also significantly decreased as compared to the level of malondialdehyde (623+/-22 nmol/g wet tissue) and reduced glutathione (226.6+/-19 microg/wet tissue) in the vehicle-treated group. The present study indicates that melatonin has a neuroprotective action in focal ischemia, which may be attributed to its antioxidant property.