Abstract
Blood samples were collected by jugular vein cannula from 6 hypophysial stalk-transected (HST) and 4 intact (INTACT) crossbred gilts at 0800, 0830 and 0900 h. Immediately after the 0900 h sample, thyrotropin releasing hormone (TRH) was injected i.v. to determine anterior pituitary gland response via release of prolactin (PRL). Blood was collected every 15 min for 1 h and every 30 min for an additional 2 h. All gilts received the dopamine (DA) agonist, bromocryptine (CB-154), s.c. at 1600 h and blood sampling and TRH challenge was repeated beginning at 0800 h the next day. Mean serum PRL concentration at 0800, 0830 and 0900 h was termed basal PRL for each day. Before CB-154, basal PRL for HST gilts was greater (P<.01) than for INTACT gilts, whereas, after CB-154, basal PRL were similar among HST and INTACT gilts. Before CB-154, TRH caused peak secretion of PRL of similar magnitude within 15 minutes in both HST and INTACT gilts; PRL decreased to basal concentration by 120 min after TRH in both groups. However, after CB-154, PRL response to TRH was blunted similarly in all gilts. These results indicate that suppression of DA pathways is an antecedent to the physiological mechanism by which a secretagogue, such as TRH, stimulates PRL secretion in the intact pig.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
