Influence of serotonergic 5-HT2C receptor antagonist mesulergine in the reversal of memory deficits induced by mCPP.

OBJECTIVE To determine the effect of non-selective 5-HT2C antagonist mesulergine and 5-HT2C agonist mCPP (metachlorophenylpiperazine) on learning acquisition (LA), short-term memory (STM) and long-term memory (LTM). STUDY DESIGN Experimental study. PLACE AND DURATION OF STUDY Department of Biochemistry, University of Karachi, from December 2009 to June 2010. METHODOLOGY Twenty-four male albino Wistar rats were used in this study. The agonist and antagonist (mCPP and mesulergine) were injected intraperitoneally at a dose 3.0 mg/kg in volumes of 1 ml/kg. Control animals were injected with saline (1 ml/kg). Animals were randomly divided into four groups (n=6). 1st being control group, 2nd being mCPP injected group, 3rd being mesulergine injected group and 4th group being injected with both mesulergine and mCPP. Behavioural activities of rats were monitored after 30 minutes of injection. For assessment of memory functions, water maze apparatus was used. RESULTS Administration of mCPP impaired STM, LTM and LA of rats. Mesulergine injected rats exhibited no alteration in memory functions. However, when it was injected with mCPP then there were no memory deficits induced by mCPP. CONCLUSION Ability of 5-HT2C receptor antagonist mesulergine to block the memory impairment effect of mCPP indicated an important regulatory role of 5-HT2C receptors in cognitive processes.