effect of alpha-lipoic acid on learning and memory deficit in a rat model of temporal lobe epilepsy

Epilepsy is a chronic neurological disorder in which patients experience spontaneous recurrent seizures and deficiency in learning and memory. Although the most commonly recommended therapy is drug treatment, some patients do not achieve adequate control of their seizures on existing drugs. New medications with novel mechanisms of action are needed to help those patients whose seizures are resistant to currently-available drugs. While alphalipoic acid as a antioxidant has some neuroprotective properties, but this action has not been investigated in models of epilepsy. Therefore, the protective effect of pretreatment with alpha-lipoic acid was evaluated in experimental model of temporal lobe epilepsy in male rats. In the present study, Wistar male rats were injected intrahippocampally with 0.9% saline[Sham-operated group], kainic acid[4 micro g] alone, or alpha-lipoic acid [25mg and 50mg/kg] in association with kainic acid[4 micro g]. We performed behavior monitoring[spontaneous seizure, learning and memory by Y-maze and passive avoidance test], intracranial electroencepholography [iEEG] recording, histological analysis, to evaluate the anti- epilepsy effect of alpha-lipoic acid in kainate-induced epileptic rats. Behavior data showed that the kainate rats exhibit spontaneous seizures, lower spontaneous alternation score inY-maze tasks [p<0.01], impaired retention and recall capability in the passive avoidance test [p<0.05]. Administration of alpha-lipoic acid, in both doses, significantly decrease the number of spontaneous seizures, improved alternation score in Y-maze task [p<0.005] and impaired retention and recall capability in the passive avoidance test [p<0.01] in kainite rats. Moreover, lipoic acid could improve the lipid peroxidation and nitrite level and superoxid dismutase activity. This study indicates that lipoic acid pretreatment attenuates kainic acid-induced impairment of short-term spatial memory in rats probably due to its antioxidant activity

Varenicline ameliorates learning and memory deficits in amyloid beta[25-35] rat model of Alzheimer's Disease

Alzheimer's disease [AD] is a enfeeble neurodegenerative disorder characterized by increased beta-amyloid [Abeta] deposition and neuronal dysfunction leading to impaired learning and recall. Among proposed risk factors, impaired cholinergic transmission is a main cause for incidence of disease. In the present study, effects of the intracerebroventricularly administration of an agonist of nicotinic cholinergic receptors, varenicline[0.5 and 2 microg/microl], on learning and memory impairments induced by intrahippocampal Abeta[25-35] injection was assessed in rats. The results showed that the intrahippocampal Abeta[25-35] injected rats exhibit lower spontaneous alternation score inY-maze tasks [p<0.05], impaired retention and recall capability in the passive avoidance test [p<0.05], and fewer correct choices [p<0.001] and more errors[p<0.001] in the RAM task. Varenicline, almost in both doses, significantly improved alternation score in Y-maze task [p<0.001], impaired retention and recall capability in the passive avoidance test [p<0.05], and correct choices in the RAM task [p<0.001]. This study indicates that varenicline pretreatment attenuates Abeta- induced impairment of short-term spatial memory in rats probably due to its agonist activity at nicotinic receptors.