Social Isolation Of Rats Research Articles

Individually reared rats: alteration in noradrenergic brain functions.

The influence of social isolation in rats on postsynaptic alpha 1- and beta-adrenergic receptors, on the cAMP generating system and on the presynaptic uptake mechanism in the central noradrenergic system was examined in different brain regions. Rearing rats in isolation from the 19th day of life for 12 weeks leads in all regions to a general tendency for a reduction in 3H-DHA binding, to an enhanced 3H-WB4101 binding and to a decreased responsiveness of the noradrenaline sensitive cAMP generating system. These changes reach significant only in the pons-medulla-thalamus region. Isolated rats showed an increased synaptosomal uptake of noradrenaline, most pronounced and significant in the hypothalamus. Our data provide further support for a disturbance in central noradrenergic function in isolated rats.

Social Isolation in Rats as a Model Psychosis(Animal models in psychosomatic disorders)

Social Isolation in Rats as a Model Psychosis(Animal models in psychosomatic disorders)

Altered behavioral responses to intense foot shock in socially-isolated rats

Male Wistar rats were isolated immediately after weaning for 12 weeks and exposed to electric foot shock of various intensities. The shock-elicited jumping behavior was measured every ten minutes for one hr. The frequency of jumping in isolated rats was lower than that in grouped and the difference between two groups was the greatest with the most intense shock. In these experimental situations, there was no significant difference in monoamine turnover rate between the two groups while noradrenaline turnover markedly increased in both groups. Chlorpromazine suppressed the jumping in a dose-dependent manner in both groups with stronger suppression in isolated rats. Methamphetamine facilitated the jumping in grouped rats dose-dependently while the drug rather depressed it in the isolated. From these results and the behavioral similarity between the isolated and 6-hydroxydopamine treated rats under foot shock situation, it was suggested that the receptor supersensitivity of central catecholaminergic neurons was involved in the behavioral change in isolated rats.

Activity and exploration in thyroid-deficient and socially-isolated rats

Rats were treated with an anti-thyroid drug during infancy, and their behavior and brain weights were later compared with control rats, and with a group of animals reared in social isolation. The brain weight of the thyroid-deficient rats was considerably smaller than that of the other two groups, but their behavior in an open-field situation was not different from that of the socially-reared controls. Isolates, on the other hand showed a marked slowing down of habituation in the open field, confirming previous reports of a failure of inhibition in these animals. The behavioral effects of social isolation do not appear to be due to a slowing down of brain development.

The Effects of Isolation Rearing on Behavioural Inhibition in the Rat

The possibility that isolation-rearing in the rat affects the development of inhibitory mechanisms was studied in a series of experiments. It was found that socially-isolated rats were (1) slower to learn both a lever-panel alternation, and a two-lever alternation schedule of reinforcement, (2) more persistent than controls in pressing a lever for food when a supply of identical “free food” was introduced into the operant chamber, but (3) similar to control rats in their response to preloading with food, a procedure which inhibited lever pressing to the same extent in the two groups. Finally, it was shown in a separate experiment that the effects of increased food deprivation on lever pressing in the presence of free food were qualitatively different from the effects of social isolation, and therefore the social/isolate difference cannot be interpreted as motivational. The possible contributions of neophobia to the difference are discussed. It is concluded that isolates may well suffer from a disinhibitory defect, but that there are probably other effects of isolation in addition.

Incentive motivation and behavioral inhibition in socially-isolated rats

Rats reared from weaning in social isolation made more lever presses than controls on an alternating two-lever DRL schedule of reinforcement, and obtained fewer rewards. Isolates showed an increased tendency both to anticipate reward on the correct lever, and to perseverate on the lever which last gave reward, but their anticipatory deficit was relatively more marked. It is suggested that isolates act as if under an effectively higher level of food motivation. Measurement of home-cage food intake showed that the normal day-time depression of food intake was less marked in isolates than in socially-grouped animals.

Incentive motivation and behavioral inhibition in socially-isolated rats.

Rats reared from weaning in social isolation made more lever presses than controls on an alternating two-lever DRL schedule of reinforcement, and obtained fewer rewards. Isolates showed an increased tendency both to anticipate reward on the correct lever, and to perseverate on the lever which last gave reward, but their anticipatory deficit was relatively more marked. It is suggested that isolates act as if under an effectively higher level of food motivation. Measurement of home-cage food intake showed that the normal day-time depression of food intake was less marked in isolates than in socially-grouped animals.

Effects of social isolation on quinine tolerance

Abstract Changes in behavior that occur after social isolation of rats might result from a change in reactivity to stimulation. This hypothesis predicts that isolated female rats will exaggerate their normal responses to preferred and to non-preferred stimuli, thus drinking less of a quinine solution and more tap water than non-isolated animals during the half-hour test period. In fact, isolated rats did drink less quinine solution than rats housed in community cages, but the prediction for tap water was not confirmed.