European Journal of Biomedical and Pharmaceutical Sciences

SUB-ANESTHETIC DOSE OF N-METHYL-D-ASPARTATE RECEPTOR ANTAGONIST (KETAMINE) DOWN REGULATES SPATIAL LEARNING AND IMPAIRS VISUAL SCENE-BASED MEMORY IN WISTER RATS

*Olorunfemi O.J., Okoseimiema S.C. and Ibeachu P.C.

ABSTRACT

The study was designed to investigate the effect of sub-chronic administration of N-methyl-D-aspartate receptor (ketamine) antagonist on spatial learning and visual scene-based memory in rats. Twenty-five albino wistar rats were arranged in five groups; group1 (Normal control), group 2(1mg/kg Ketamine), group 3(3mg/kg Ketamine), group 4(6mg/kg Ketamine), and group 5 (epinephrine drug). Drug treatments lasted for 4 weeks across the groups The rats in various groups were made to undergo a total of nine (9) trials of some spatial learning and memory tests which include: navigational maze (adaptive locomotion), passive avoidance test (episodic memory), Barnes maze test (visual scene-based memory). The neurobehavioral activities exhibited by the test and control groups were recorded and analyzed using ANOVA. Observations from the adaptive locomotion study revealed that there was a significant decline (p< 0.05) in motor function especially as the treatment progressed and in a dose-dependent pattern. The quality of locomotion task performance also decreased as the dose of ketamine increased. Results from visual scene-based memory test revealed that in the ketamine-administered groups, quality of visual perception and memory retrieval became significantly (p< 0.05) abysmal especially in group 4(6mg/kg ketamine) in the week 3 of the study when compared to both the negative and positive controls. Assessments for the episodic memory study interestingly showed ketamine treatment across the 3-dose level up regulated memory retrieval and the experience was dose-dependent. Pain episode seemed to consolidate spatial learning aspect of memory. From the results obtained in the study, ketamine at these doses could be favorable towards consolidation of episodic memory but could antagonistic to visual scene-based memory alongside decline of adaptive locomotion and motor coordination. In order words, it can be seen that the use of different doses of ketamine can cause a decrease in spatial behavior in albino wistar rats.

Keywords: Ketamine, wister rats, Navigation maze, Adaptive locomotion, Visual scene-based memory.