Nicergoline is an ergot derivative used to treat senile dementia and other disorders with vascular origins.Target: Alpha-1A adrenergic receptorNicergoline acts by inhibiting the postsynaptic alpha(1)-adrenoceptors on vascular smooth muscle. This inhibits the vasoconstrictor effect of circulating and locally released catecholamines (epinephrine and norepinephrine), resulting in peripheral vasodilation. Nicergoline displaced [3H]-prazosin bound to rat forebrain membranes pretreated with chloroethylclonidine (pKi = 9.9 +/- 0.2) at concentrations 60-fold lower than in rat liver membranes (pKi = 8.1 +/- 0.2). Finally, of the nicergoline metabolites studied, lumilysergol acted as a modest alpha 1 antagonist (bromonicotinic acid was devoid of alpha 1 antagonist activity). In conclusion, nicergoline is a potent and selective alpha 1A-adrenoceptor subtype antagonist, an alpha 1-adrenoceptor subtype which is mainly represented in resistance arteries [1].

References:
[1]. Alvarez-Guerra, M., N. Bertholom, and R.P. Garay, Selective blockade by nicergoline of vascular responses elicited by stimulation of alpha 1A-adrenoceptor subtype in the rat. Fundam Clin Pharmacol, 1999. 13(1): p. 50-8.