Urocortin III-immunoreactive projections in rat brain: partial overlap with sites of type 2 corticotrophin-releasing factor receptor expression.
Urocortin (Ucn) III, or stresscopin, is a new member of the corticotropin-releasing factor (CRF) peptide family identified in mouse and human. Pharmacological studies showed that Ucn III is a high-affinity ligand for the type 2 CRF receptor (CRF-R2). To further understand physiological functions the peptide may serve in the brain, the distribution of Ucn III neurons and fibers was examined by in situ hybridization and immunohistochemistry in the rat brain. Ucn III-positive neurons were found predominately within the hypothalamus and medial amygdala. In the hypothalamus, Ucn III neurons were observed in the median preoptic nucleus and in the rostral perifornical area lateral to the paraventricular nucleus. The Ucn III fibers were distributed mainly in the hypothalamus and limbic structures. Hypothalamic regions that were innervated prominently by Ucn III fibers included the ventromedial nucleus, medial preoptic nucleus, and ventral premammillary nucleus. Outside the hypothalamus, the densest projections were found in the intermediate part of the lateral septum, posterior division of the bed nucleus stria terminalis, and the medial nucleus of the amygdala. Several major Ucn III terminal fields identified in the present study, including the lateral septum and the ventromedial hypothalamus, are known to express high levels of CRF-R2. Thus, these anatomical data strongly support the notion that Ucn III is an endogenous ligand for CRF-R2 in these areas. These results also suggest that Ucn III is positioned to play a role in mediating physiological functions, including food intake and neuroendocrine regulation.
Li
Chien
C
The Clayton Foundation Laboratories for Peptide Biology and Laboratory of Neuronal Structure and Function, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
Vaughan
Joan
J
Sawchenko
Paul E
PE
Vale
Wylie W
WW
D000679:Amygdala / Q000166:cytology / Q000378:metabolism; D000818:Animals; D000918:Antibody Specificity; D001921:Brain / Q000166:cytology* / Q000378:metabolism*; D003346:Corticotropin-Releasing Hormone / Q000096:biosynthesis* / Q000235:genetics; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D009928:Organ Specificity; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D018019:Receptors, Corticotropin-Releasing Hormone / Q000096:biosynthesis*; D020665:Septum of Brain / Q000166:cytology / Q000378:metabolism; D054832:Urocortins
C101531:CRF receptor type 2; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D054832:Urocortins; D003346:Corticotropin-Releasing Hormone