CCK mRNA expression in neuroendocrine CRH neurons is increased in rats subjected to an immune challenge.

The expression of cholecystokinin (CCK) mRNA in neuroendocrine corticotropin-releasing hormone (CRH) neurons of the hypothalamic paraventricular nucleus (PVN) of male rats was examined 8 h following an acute immune challenge by intraperitoneal lipopolysaccharide (LPS, 250 microg/kg). Both quantitative, macroautoradiographic, single-label radioactive in situ hybridization histochemistry (ISHH) and qualitative dual-label ISHH were performed. Compared to controls, LPS-injected rats displayed increased (185%) parvicellular CCK mRNA expression levels, occurring in a majority (70%) of CRH neurons as revealed by dual-label ISHH.

Immune challenge-stimulated hypophysiotropic corticotropin-releasing hormone messenger RNA expression is associated with an induction of neurotensin messenger RNAs without alteration of vasopressin messenger RNAs.

The corticotropin-releasing hormone neurons of the hypothalamic paraventricular nucleus are the final common pathway of the neuroendocrine adaptative response to a variety of stressors. To meet varied homeostatic needs, corticotropin-releasing hormone neurons exhibit a marked phenotypical plasticity, enabling them to rapidly modify their neuroendocrine output. In particular, they synthesize the neuropeptides vasopressin and neurotensin.