Effects of pinealectomy of rams on secretory profiles of luteinizing hormone, testosterone, prolactin and cortisol.
In a study of pineal gland influences on hormone secretory profiles, blood samples were collected at 20 min intervals for 26 h from 4 pinealectomized and 4 sham-operated rams which were subjected to a 14.5 h daily photoperiod. Plasma levels of luteinizing hormone (LH) and testosterone (T) underwent rapid pulsatile fluctuations in all rams. Pinealectomized rams produced more LH than the sham-operated rams and a similar trend was recorded for plasma T data, since T secretion closely followed that of LH. A nocturnal elevation of plasma prolactin (Prl) levels displayed by sham-operated rams was substantially abolished by pinealectomy. Also a rise in cortisol secretion during the morning hours recorded from 3 of the sham-operated rams was absent in 2 of the pinealectomized rams. The possible significance of the pineal gland in the regulation of secretion of these hormones is discussed.
D000818:Animals; D003624:Darkness; D006854:Hydrocortisone / Q000097:blood*; D007700:Kinetics; D008027:Light; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D010507:Periodicity; D010870:Pineal Gland / Q000502:physiology*; D011388:Prolactin / Q000097:blood*; D012756:Sheep; D013739:Testosterone / Q000097:blood*
D013739:Testosterone; D011388:Prolactin; D007986:Luteinizing Hormone; D006854:Hydrocortisone