Vol. 4, Issue 8 (2015)

Author(s):
Dr. Somnth M Matule and Dr. SA Jadhav

Abstract:
Results: Mianserin at 1.25, 2.5 and 5 mg/kg i.p. did significantly antagonise 5-HT_2C receptor agonist fluoxetine induced PEs and 10 and 20 mg/kg i.p. mianserin abolished fluoxetine induced PEs. Thus 1.25 to 20 mg/kg doses of mianserin possess significant 5-HT_2C receptor blocking activity. Mianserin at 5, 10 and 20 mg/kg i.p. doses does not block presynaptic D2 DA autoreceptors as with these doses it failed to antagonise low dose (0.1 mg/kg) apomorphine induced catalepsy. Mianserin at 5, 10 and 20 mg/kg i.p. doses is devoid of postsynaptic D2 and D1 DA receptor blocking activity as at these doses it did not antagonise apomorphine induced SB and did not produce catalepsy in rats. Conclusion: Mianserin at 5, 10 and 20 mg/kg doses blocks the 5-HT_2C receptors on the nigrostriatal DAergic neurons and remove the inhibitory influence of 5-HT on the nigrostriatal DAergic neurons which further causes increase in intraneuronal synthesis of DA and hence intraneuronal stores of DA. So pretreatment with 5, 10 and 20 mg/kg i.p. makes more DA available for release and resultant potentiation of dexamphetamine SB and antagonism of haloperidol catalepsy.