Ontogeny of GABA-ergic and dopaminergic mediation of gnawing behavior in the mouse

Examined the ontogenetic course of dopaminergically mediated gnawing and the potentiation of this behavior by muscimol (a gamma-aminobutyric acid receptor agonist) in developing and young adult mice using a time-sampling or a corrugated paper procedure. In Exp I, the older group (14-53 days), displayed a dose-dependent gnawing behavior after intraperitoneal injections of methylphenidate ([MTPD], 20, 30, 50 mg/kg). In 5-, 8-, 11-, and 14-day-old pups, MTPD (10, 20, 50 mg/kg) evoked stereotyped gnawing. Muscimol pretreatment (0.025-2.3 mg/kg) induced a clear-cut potentiation of gnawing elicited by MTPD (10 or 20 mg/kg) as early as 8 days of age. It is argued that the effectiveness of MTPD in inducing gnawing-licking among 5-day-old pups confirms the early maturation of central dopamine receptors reported in the literature. ((c) 1997 APA/PsycINFO, all rights reserved)