Effects of isolation-rearing on cholinergic receptor sensitivity and passive avoidance behavior in adult rats

The effects of isolation-rearing on the sensitivity of cholinergic receptors and passive avoidance behavior were studied to examine the activity of the central cholinergic system. Rat pups were weaned from mother on 15th day postpartum and thereafter isolated to adulthood. At three months of age the thermic response to three different doses of oxotremorine were measured. One day following oxotremorine challenge study, the animals were subjected to passive avoidance training and retention was measured 24-hr later. Isolated animals exhibited an enhanced cholinomimetic-induced hypothermia and an increased latency in passive avoidance test which may reflect an altered sensitivity of central cholinegic system in isolated animals. The possible involvement of an interaction between cholinergic and monoaminergic system in isolated animals are discussed.