Differential distribution of urocortin- and corticotropin-releasing factor-like immunoreactivities in the rat brain

• Published in: Neuroscience Vol. 92; no. 1; pp. 281 - 291
• Main Authors: Morin, S.M., Ling, N., Liu, X.-J., Kahl, S.D., Gehlert, D.R.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.1999; Elsevier
• Subjects: Animals; Biological and medical sciences; Brain - cytology; Brain - metabolism; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; corticotropin-releasing factor; Corticotropin-Releasing Hormone - metabolism; Edinger–Westphal nucleus; Fundamental and applied biological sciences. Psychology; Immunohistochemistry; Male; Neurons - metabolism; Rats; Rats, Sprague-Dawley; sphenoid nucleus; supraoptic nucleus; Tissue Distribution - physiology; urocortin; Urocortins; Vertebrates: nervous system and sense organs; sphenoid nucleus; DAB, diaminobenzidine; urocortin; EDTA, ethylenediaminetetra-acetate; SPA, scintillation proximity assay; SPRIA, scintillation proximity radioimmunoassay; EW, Edinger–Westphal nucleus; IR, -like immunoreactivity; corticotropin-releasing factor; PBS, phosphate-buffered saline; Edinger–Westphal nucleus; SO, supraoptic nucleus; supraoptic nucleus; BNST, bed nucleus stria terminalis; MVe, medial vestibular nucleus; immunohistochemistry; CRF, corticotropin-releasing factor; PLP, paraformaldehyde–lysine–periodate fixative; Rat; Rodentia; Central nervous system; Corticotropin releasing factor; Edinger Westphal nucleus; Neuropeptide; Hypothalamic hormone; Vertebrata; Mammalia; Distribution; Hormone releasing factor; Supraoptic nucleus; Brain (vertebrata)
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(98)00732-5

Urocortin, a novel 40 amino acid neuropeptide, is a member of the corticotropin-releasing factor family. With 45% homology to corticotropin-releasing factor, urocortin binds with similar affinity to the corticotropin-releasing factor-1 and corticotropin-releasing factor-2 receptors and may play a role in modulating many of the same systems as corticotropin-releasing factor. To assess whether urocortin and corticotropin-releasing factor are localized in the same regions of the brain, we compared the distribution of urocortin- and corticotropin-releasing factor-like immunoreactivities in the rat central nervous system. Polyclonal antibodies to rat corticotropin-releasing factor and rat urocortin were generated and utilized to map the distribution of corticotropin-releasing factor- and urocortin-like immunoreactivities throughout the rat forebrain and brainstem. Characterization of the antibodies by radioimmunoassay showed no cross-reactivity with related peptides. Male Sprague–Dawley rats were treated with colchicine for 18–24 h. Following colchicine treatment, the rats were perfused with paraformaldehyde–lysine–periodate fixative and their brains removed. Serial coronal sections were taken throughout the rat brain and processed for either corticotropin-releasing factor- or urocortin-like immunoreactivity. Urocortin-like immunoreactivity shows a discrete localization within several regions including the supraoptic nucleus, the median eminence, Edinger–Westphal nucleus and the sphenoid nucleus. This is in contrast to the more abundant corticotropin-releasing factor-like immunoreactivity. Regions containing high levels of corticotropin-releasing factor immunoreactivity include the lateral septum, paraventricular nucleus of the hypothalamus, median eminence and locus coeruleus. There are a few regions that contain both urocortin-immunoreactive and corticotropin-releasing factor-immunoreactive cells, such as the supraoptic nucleus and the hippocampus. Therefore, urocortin and corticotropin-releasing factor appear to have different distribution patterns which may be indicative of their respective physiological functions.