Effect of social experience on dopamine-stimulated adenylyl cyclase activity and G protein composition in chick...

The stimulation of adenylyl cyclase (AC) by dopamine was investigated in membrane fractions of the forebrain areas mediorostral neostriatum/hyperstriatum ventrale (MNH) and lobus parolfactorius (LPO) of 8-day-old domestic chicks that had been raised under different social conditions: group A, socially isolated; group B, imprinted on an acoustic stimulus; group C, trained but nonimprinted; and group D, reared in small groups. Only in the brain of the socially experienced groups could cyclic AMP (cAMP) synthesis be stimulated by dopamine, but not in the socially isolated animals (group A). Ligand binding studies of dopamine D1- and D2-type receptors in membrane fractions did not reveal differences between socially experienced and isolated animals. Forskolin stimulation of total AC in MNH and LPO membrane fractions revealed a significantly enhanced AC stimulation in the socially reared but not in the imprinted group compared with isolated controls. Stimulation of AC by the G protein activator guanylylimidodiphosphate was significantly increased in the MNH and the LPO of socially reared chicks compared with isolated control animals. These results suggest that early postnatal social experience modulates the rate of cAMP synthesis and that these lasting changes are not due to changes of dopamine receptors but are related to increased AC activities and to increased sensitivity of Gs protein.