Transient focal ischemia induces motor deficit but does not impair the cognitive function in middle cerebral artery occlusion model of stroke in rats Yogendra K. Gupta * , Kusum Sinha, Geeta Chaudhary Neuropharmacology Laboratory, Department of Pharmacology, All India Institute of Medical Sciences, New Delhi 110029, India Abstract The effect on cognition was evaluated in the transient ischemia model of stroke in rats. Male Wistar rats were subjected to 2 h of transient ischemia by occluding the middle cerebral artery using the 4-0 intraluminal nylon thread. Neurological tests performed after 24 h, 7 and 15 days of middle cerebral artery (MCA) occlusion showed motor impairment as evidenced by decrease in the rota rod performance test. This was also confirmed histologically. However, when the learning and memory tests were performed, no change was observed in the learning and behavior as evidenced by insignificant difference in the retention latency in the passive avoidance test (334 F 31 s) and the transfer latency in the elevated plus maze (11 F 4.5 s) as compared to the sham-operated rats 369 F 34 and 8 F 1.7 s, respectively. The results of the present study demonstrates that transient occlusion of middle cerebral artery does not impair the learning and memory behavior of the rats. D 2002 Elsevier Science B.V. All rights reserved. Keywords: Transient ischemia; Cognition; Motor deficit; Rat 1. Introduction Acute ischemic stroke is the third largest cause of mortality and the single largest cause of long-lasting dis- ability in adults [1]. Survivors of stroke manifest abrupt development of neurological deficit that can range from nausea, headache, blurred vision, convulsions and loss of consciousness. A wide range of motor and sensory motor deficits including tremor, lack of coordination and partial paralysis is also seen [1]. Evidence suggests that apart from motor impairment, cognitive deficits are also seen in survi- vors of stroke [2]. Therefore, for evaluation of potential therapeutic agents, assessment of cognitive deficit along with motor and histological end points is now being considered. Several experimental studies using models of global and focal ischemia have demonstrated the occurrence of cogni- tive deficits after induction of stroke [3–5]. However, the data regarding the effect of transient focal ischemia on learning and memory is scanty. Since transient ischemia is a well-known feature seen in humans during cerebral embolism or during recurrent transient ischemic attacks, it was thought worthwhile to investigate the effect of 2 h of ischemia followed by reperfusion on the cognitive func- tions. In the present study, the effect of learning and memory was assessed in rats after middle cerebral artery (MCA) occlusion followed by reperfusion, which is the most widely used model of transient focal ischemia. 2. Material and methods 2.1. Animals Adult male Wistar rats weighing 200 – 250 g were used in the study. The animals were procured from the central animal house facility at All India Institute of Medical Sciences, New Delhi. The rats were group-housed in poly- propylene cages (38 Â 23 Â 10 cm) with not more than five animals per cage and maintained under standard laboratory conditions with natural dark and light cycle (14 F 1 h light; 10 F 1 h dark). They were allowed free access to standard dry rat diet (Golden Feeds, India) and tap water ad libitum. All procedures described were reviewed and approved by the Institutional Animal Ethics Committee. The rats were 0022-510X/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved. PII:S0022-510X(02)00303-9 * Corresponding author. Tel.: +91-011-659-3684; fax: +91-011-686- 4789. E-mail address: ykg@hotmail.com (Y.K. Gupta). www.elsevier.com/locate/jns Journal of the Neurological Sciences 203 – 204 (2002) 267 – 271