Effects of Acute and Chronic Inflammation on Vasopressin Expression in the Paraventricular Nucleus of the Hypothalamus

Abstract

Inflammation can lead to a suite of behavioral changes known as sickness behaviors, which have been implicated in the etiology of chronic inflammatory disease. Here, we examine the role of acute and chronic induction of inflammation on vasopressin (AVP) expression in the paraventricular nucleus of the hypothalamus (PVN) of female mice. To test, adult female C57B6/J mice were injected with lipopolysaccharide (LPS) at two different dosages and schedules to induce acute (1.0mg/kg, once) and chronic (0.25mg/kg LPS, eight times) inflammatory responses. The acute dose has previously been demonstrated to induce sickness behaviors, as measured by the open field test and a social interaction test; however, these measures were unaffected by the chronic administration of LPS. AVP mRNA expression in the PVN was measured using fluorescent in situ hybridization (FISH) and fluorescent microscopy. Both the acute and chronic administration of LPS resulted in an increase in PVN AVP expression without a change in the area of this expression. This increase in AVP in the PVN occurred despite the lack of sickness behavior, suggesting that further work is necessary to characterize the role of AVP in the PVN in these chronic and acute inflammatory responses.