Lesion of the anteroventral third ventricle (AV3V) reduces hypothalamic activation and hypophyseal hormone secretion induced by lipopolysaccharide in rats

This study examined whether electrolytic ablation of the periventricular anteroventral third ventricle (AV3V) region would affect the hypothalamic activation and the increase of hypophysial hormone secretion induced by systemic injection of lipopolysaccharide (LPS) in rats. LPS significantly increased the number of cells showing Fos immunoreactivity in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus (P < 0.05) and also increased plasma levels of vasopressin, oxytocin, adrenocorticotropin and corticosterone (P < 0.05). AV3V lesion significantly reduced LPS-induced Fos immunoreactivity (P < 0.05) and vasopressin and oxytocin secretion (P < 0.05). Elevations in adrenocorticotropin but not in plasma corticosterone after LPS were affected by prior AV3V lesions. These findings demonstrate that LPS-induced Fos expression in the PVN and SON, and hypophysial hormone secretion is dependent on the integrity of the AV3V region.