Developmental Pattern of VIP Binding Sites in the Human Hypothalamus MOHAMED NAJIMI, FATIMA RACHIDI, ABDELKRIM AFIF, AND FATIHA CHIGR Laboratory of Functional and Pathologic Biology, Faculty of Sciences and Techniques, 23000 B´ eni-Mellal, Morocco ABSTRACT: We have studied the developmental patterns of vasoactive in- testinal polypeptide (VIP) binding sites in the human hypothalamus. VIP recognition sites were widely distributed throughout the rostrocaudal ex- tent of the hypothalamus. VIP binding was generally low in the fetal and neonatal periods and a tendency in increasing densities was observed during postnatal development. The age comparison of binding density indicates variations in several structures. Thus, the densities were higher in older infants in the preoptic area, lamina terminalis, and infundibular (IN) nucleus. These differences suggest the implication of VIP receptors in the development of this brain structure and the maintenance of its various functions. KEYWORDS: VIP binding sites; hypothalamus; development; human; fetal and neonatal periods; postnatal period INTRODUCTION Vasoactive intestinal polypeptide (VIP) is a 28-amino acid polypeptide orig- inally isolated from the porcine duodenum, 1 that is also present in the central nervous system (CNS) of many vertebrates including mammals. Numerous studies have shown that VIP exerts pleiotropic physiological functions: in ad- dition to its role as a neurotransmitter/neuromodulator, VIP has also been found to act as a hormone/neurohormone and, a neurotrophic or neuroprotective fac- tor. 2 These various biological effects of VIP are mediated through interaction with two receptor types, termed VPAC1 and VAPC2 receptors, which recognize with a similar high affinity both VIP and pituitary adenylate cyclase-activating polypeptide (PACAP). 3 With regard to its neuroendocrine function and despite the important role of VIP and its receptors in the hypothalamus during devel- opment, there is no information concerning the ontogeny of VIP binding sites Address for correspondence: Mohamed Najimi, Laboratory of Functional and Pathologic Biology, Faculty of Sciences and Techniques, 23000 B´ eni-Mellal, Morocco. Voice: +212-23485112; fax: +212- 23485201. e-mail: mnajimi1@fstbm.ac.ma Ann. N.Y. Acad. Sci. 1070: 462–467 (2006). C  2006 New York Academy of Sciences. doi: 10.1196/annals.1317.062 462