Sm. Morin et al., Differential distribution of urocortin- and corticotropin-releasing factor-like immunoreactivities in the rat brain, NEUROSCIENC, 92(1), 1999, pp. 281-291
Urocortin, a novel 40 amino acid neuropeptide, is a member of the corticotr
opin-releasing factor family. With 45% homology to corticotropin-releasing
factor, urocortin binds with similar affinity to the corticotropin-releasin
g factor-1 and corticotropin-releasing factor-2 receptors and may play a ro
le in modulating many of the same systems as corticotropin-releasing factor
. To assess whether urocortin and corticotropin-releasing factor are locali
zed in the same regions of the brain, we compared the distribution of uroco
rtin- and corticotropin-releasing factor-like immunoreactivities in the rat
central nervous system. Polyclonal antibodies to rat corticotropin-releasi
ng factor and rat urocortin were generated and utilized to map the distribu
tion of corticotropin-releasing factor- and urocortin-like immunoreactiviti
es throughout the rat forebrain and brainstem. Characterization of the anti
bodies by radioimmunoassay showed no crossreactivity with related peptides.
Male Sprague-Dawley rats were treated with colchicine for 18-24 h. Followi
ng colchicine treatment, the rats were perfused with paraformaldehyde-lysin
e-periodate fixative and their brains removed. Serial coronal sections were
taken throughout the rat brain and processed for either corticotropin-rele
asing factor- or urocortin-like immunoreactivity. Urocortin-like immunoreac
tivity shows a discrete localization within several regions including the s
upraoptic nucleus, the median eminence, Edinger-Westphal nucleus and the sp
henoid nucleus. This is in contrast to the more abundant corticotropin-rele
asing factor-like immunoreactivity. Regions containing high levels of corti
cotropin-releasing factor immunoreactivity include the lateral septum, para
ventricular nucleus of the hypothalamus, median eminence and locus coeruleu
s.
There are a few regions that contain both urocortin-immunoreactive and cort
icotropin-releasing factor-immunoreactive cells, such as the supraoptic nuc
leus and the hippocampus. Therefore, urocortin and corticotropin-releasing
factor appear to have different distribution patterns which may be indicati
ve of their respective physiological functions. (C) 1999 IBRO. Published by
Elsevier Science Ltd.