Expressions of immediate early genes in the hypothalamic paraventricular and supraoptic nuclei of rats after acute osmotic stimulus.

Abstract

Monitoring the immediate early genes (IEGs) is a useful method for following stress-induced cellular response in the neuroendocrine system. We have examined the transcriptional activities of IEGs (c-fos, jun-B, NGFI-A and NGFI-B) and arginine vasopressin (AVP) gene in the hypothalamic paraventicular (PVN) and supraopic nuclei (SON) of rats after acute osmotic stimulus, using in situ hybridization histochemistry. After intraperitoneal (i.p.) administration of hypertonic saline (2% body weight, 900 mOsm/kg), the expressions of all IEGs in the PVN and SON increased significantly as early as 10 min, peaked at 30 min and maintained until 60 min. The level of AVP heteronuclear (hn) RNA also peaked at 30 min, although maintained until 180 min. The expressions of all IEGs also increased dose-dependently in response to the concentration of i.p. administration of saline (more than 600 mOsm/kg). These results showed that induction of IEGs as well as the level of AVP hnRNA in the PVN and SON is a useful marker for following the neuroendocrine responses to acute osmotic change in rats. [Jpn J Physiol 54 Suppl:S218 (2004)]