The actions of carbachol were studied on the firing response of neostriatal neurons recorded intracellularly from in vitro slice preparations of the rat brain. Carbachol (1-10 microM) reversibly reduced the afterhyperpolarization in neostriatal neurons. This effect was accompanied by an increase in both firing frequency and input resistance in the subthreshold voltage range. Atropine (1-10 microM) reversibly blocked carbachol effects, suggesting muscarinic receptor modulation. Pirenzepine (up to 1 microM), but not AF-DX 384 (10 microM) or gallamine (30 microM), blocked the effects of carbachol on the afterhyperpolarization. The protein kinase C activator, phorbol 12,13 dibutyrate, but not the inactive phorbol ester, 4 alpha-phorbol 12-myristate 13-acetate, mimicked carbachol effects. The results suggest that muscarinic receptors, probably of the M1 type, regulate neostriatal excitability by modulating afterhyperpolarization.
        
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Pineda JC, Bargas J, Flores-Hernandez J, Galarraga E (1995) Muscarinic receptors modulate the afterhyperpolarizing potential in neostriatal neurons European Journal of Pharmacology281: 271-7
Pineda JC, Bargas J, Flores-Hernandez J, Galarraga E (1995) European Journal of Pharmacology281: 271-7