PEPTIDE N-TYPE AND P Q-TYPE CA2+ BLOCKERS INHIBIT STIMULANT-INDUCED HYPERACTIVITY IN MICE/

omega-Constoxin GVIA and omega-agatoxin IVA are specific peptide block ers of N- and P/Q-type calcium channel, respectively. Effects of their intracerebroventricular injection (1-3 pmol/mouse) on psychostimulant -induced hyperactivity were investigated in mice, omega-Conotoxin GVIA antagonized methylphenidate-, methamphetamine- and phencyclidine-indu ced hyperactivity in a dose-dependent manner. omega-Agatoxin IVA block ed methylphenidate-induced but not methamphetamine- or phencyclidine-i nduced hyperactivity. Neither peptides showed any effect on apomorphin e-induced hyperactivity or spontaneous activity, suggesting that the i nhibitory effects on psychostimulant-induced hyperactivity are not due to dopamine receptor blockage or nonspecific behavioral depression. A ntagonism of calcium channels, particularly N-type, may ameliorate act ivation of the dopaminergic system induced by increased dopamine relea se. (C) 1998 Elsevier Science Inc.