CORTICOTROPIN RELEASING HORMONE (CRH) IN NORMAL AND PREGNANT UTERUS: PHYSIOLOGICAL IMPLICATIONS

1. INTRODUCTION

Corticotropin-releasing hormone (CRH), is a 41-amino acid peptide, responsible not only for the endocrine but also the autonomic, immunological and behavioural responses of mammalian organisms to stress (1). This neuropeptide is mainly synthesized in the hypothalamus and is secreted into the hypophysial-portal circulation in response to stress (1-3). Its major role is the regulation of the hypothalamus-pituitary-adrenal (HPA) axis through induction of the proopiomelanocortin (POMC) gene and the secretion of corticotropin (ACTH) from anterior pituitary (4). The CRH gene is also expressed in other intracranial sites and in an increasing number of peripheral tissues, many of which are unrelated to the activity of HPA axis. Many investigators have shown that immunoreactive CRH (ir-CRH) and CRH mRNA are present in the adrenal medulla, lymphocytes, pancreas, lung, liver, stomach and duodenum (5-10). Furthermore, they are present in human placenta and in a number of reproductive tissues (table 1), including ovaries and testes. CRH is detectable in rat and human inflammatory sites, acting as an autocrine or paracrine proinflammatory regulator (11). It has been shown that immunoneutralization of local CRH attenuates the inflammatory response.