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

The stimulation of adenylyl cyclase (AC) by dopamine was investigated in me mbrane fractions of the forebrain areas mediorostral neostriatum/hyperstria tum ventrale (MNH) and lobus parolfactorius (LPO) of 8-day-old domestic chi cks that had been raised under different social conditions: group A, social ly isolated; group B, imprinted on an acoustic stimulus; group C, trained b ut nonimprinted; and group D, reared in small groups. Only in the brain of the socially experienced groups could cyclic AMP (cAMP) synthesis be stimul ated by dopamine, but not in the socially isolated animals (group A). Ligan d binding studies of dopamine D-1- and D-2-type receptors in membrane fract ions did not reveal differences between socially experienced and isolated a nimals. Forskolin stimulation of total AC in MNH and LPO membrane fractions revealed a significantly enhanced AC stimulation in the socially reared bu t not in the imprinted group compared with isolated controls. Stimulation o f AC by the G protein activator guanylylimidodiphosphate was significantly increased in the MNH and the LPO of socially reared chicks compared with is olated control animals. These results suggest that early postnatal social e xperience modulates the rate of cAMP synthesis and that these lasting chang es are not due to changes of dopamine receptors but are related to increase d AC activities and to increased sensitivity of G(s) protein.