Proteome and radioimmunoassay analyses of pituitary hormones and proteins in response to feed restriction of dairy cows.
The hypothalamic-pituitary system controls homeostasis during feed energy reduction. In order to examine which pituitary proteins and hormone variants are potentially associated with metabolic adaptation, pituitary glands from ad libitum and energy restrictively fed dairy cows were characterized using RIA and 2-DE followed by MALDI-TOF-MS. We found 64 different spots of regulatory hormones: growth hormone (44), preprolactin (16), luteinizing hormone (LH) (1), thyrotropin (1), proopiomelanocortin (1) and its cleavage product lipotropin (1), but none of these did significantly differ between feeding groups. Quantification of total pituitary LH and prolactin concentrations by RIA confirmed the results obtained by proteome analysis. Also, feed energy restriction provoked increasing non-esterified fatty acid, decreasing prolactin, but unaltered glucose, LH and growth hormone plasma concentrations. Energy restriction decreased the expression of glial fibrillary acidic protein, triosephosphate isomerase, purine-rich element-binding protein A and elongation factor Tu, whereas it increased expression of proline synthetase co-transcribed homolog, peroxiredoxin III, β-tubulin and annexin A5 which is involved in the hormone secretion process. Our results indicate that in response to feed energy restriction the pituitary reservoir of all posttranslationally modified hormone forms remains constant. Changing plasma hormone concentrations are likely attributed to a regulated releasing process from the gland into the blood.
Research Unit Nutritional Physiology Oskar Kellner, Leibniz Institute for Farm Animal Biology (FBN), Dummerstorf, Germany. b.kuhla@fbn-dummerstorf.de
Björn
B
Kuhla
Dirk
D
Albrecht
Rupert
R
Bruckmaier
Torsten
T
Viergutz
Gerd
G
Nürnberg
Cornelia C
CC
Metges
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D003612:Dairying; D004032:Diet / Q000662:veterinary; D002149:Energy Intake; D005260:Female; D005508:Food Deprivation; D007774:Lactation; D010902:Pituitary Gland / Q000378:metabolism; D010907:Pituitary Hormones / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism*; D011863:Radioimmunoassay
D010907:Pituitary Hormones; D020543:Proteome