Horse plasma corticotrophin-releasing hormone (CRH): characterisation and lack of a late gestational rise or a plasma CRH-binding protein.
Immunoreactive corticotrophin-releasing hormone (irCRH) was present in methanolic extracts of equine peripheral blood and showed no elevation in maternal peripheral serum in late gestation (0.54 +/- 0.25 pmol/l; mean +/- S.D.) compared with control horses (0.41 +/- 0.15 pmol/l). The irCRH of methanolic extracts of pituitary venous plasma had a similar elution position following reverse-phase HPLC to synthetic human CRH(1-41) and to irCRH released from horse stalk-median eminence tissue incubated in vitro. Gel chromatographic studies showed no evidence for a plasma CRH-binding protein (CRHBP) analogous to that found in human plasma in either peripheral blood from normal or pregnant horses or in pituitary venous plasma sampled from a cannulated horse. CRH-binding activity was detectable in peripheral plasma from one horse, however the molecular size of this was indicative of a gamma-globulin rather than the 37 kDa CRHBP. These studies suggest that, unlike in the human, CRH does not rise to high values in late gestation nor circulate in a bound form in equine plasma.
Department of Endocrinology, Christchurch Hospital, New Zealand.
M J
MJ
Ellis
J H
JH
Livesey
R A
RA
Donald
D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003346:Corticotropin-Releasing Hormone / Q000097:blood* / Q000737:chemistry; D005260:Female; D005865:Gestational Age; D006736:Horses / Q000097:blood*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood*
D003346:Corticotropin-Releasing Hormone