Patterns of adrenocorticotropin secretagog release in response to social interactions and various degrees of novelty.

Abstract

Colchicine blockade of axonal transport from the paraventricular nucleus to the median eminence was used to indirectly infer ACTH secretagog release in response to the psychological stressors of social interactions and various degrees of novelty. Placing a rat in a new cage with either the smell or presence of a novel conspecific decreased arginine vasopressin and oxytocin (OT) contents, but not corticotropin-releasing factor content. Secretagog contents were unchanged in rats in their home cages faced with a novel conspecific. Secretagog release during social stress is thus primarily a function of being in a novel setting. For different degrees of novelty, rats were placed in either a novel cage, a novel bucket, or a novel bucket smelling of another rat. Whereas secretagog contents were unchanged with a novel cage, OT content alone decreased in response to both the bucket and the unclean bucket. Despite a graded corticosterone response, there was no distinction in the OT response, suggesting that the colchicine technique cannot accurately reflect gradations of stressors.