Dopamine-GABAergic mechanisms of rearing and locomotion in infant and weanling mice

Examined tue modulatory effects of the gamma-aminobutyric acid(GABA)-A agonist muscimol on supported rearing and locomotion induced by the indirect dopamine agonist D-amphetamine (DAM). A total of 288 infant, weanling, and adult outbred mice were tested in 2 experiments. In adult mice, muscimol at 1,3 mg/kg DAM-induced locomotion but not rearing, whereas 1,9 mg/kg muscimol blocked both behaviors. While 0,025 mg/kg muscimol reduced 2mg/kg DAM-induced rearing without altering locomotion in infants, it affected neither rearing nor locomotion in weanlings. In infant mice, 0,075 mg/kg muscimol engendered gnawing and self-biting, a typical effect of dopamine^GABAergic pharmacological activation. Maturation of dopamine^GABAergic behavioral functions may follow a near-monotonic continuity starting a few days after birth. ((c) 1997 APA/PsycINFO, all rights reserved)