Influence of anaesthetics, mating, premature delivery, the time of day of blood sampling, and suckling on plasma levels of luteinizing hormone in hamsters.
The influence of several factors on immunoreactive LH levels in peripheral plasma of female hamsters was investigated. The LH values for animals anaesthetized with either sodium pentobarbitone or chloral hydrate were significantly lower (P smaller than 0-01) than those values obtained for hamsters sampled under ether anaesthesia. Mating on the night of pro-oestrus resulted in increased LH levels (P smaller 0-01) the following morning as compared with the levels in control females not caged with males. The LH levels were relatively low (13 plus or minus 2 (S.E.M.) ng/ml) on the afternoon (16.00-18.00 h) of day 15 of pregnancy and also on the morning (09.00-10.00 h) of day 16 before (7 plus or minus 1 ng/ml) and after parturition (4 plus or minus 0-2 ng/ml), but rose severalfold (561 plus or minus 201 ng/ml) on the afternoon post partum. When premature delivery was induced on day 15 of pregnancy by administration of prostaglandin E2 the LH levels did not rise on the afternoon of this day (29 plus or minus 11 ng/ml), but did so on the following afternoon (213 plus or minus 115 ng/ml), at the same interval post coitum as in normal delivery. Marked increases in the concentration of LH in plasma were observed on the afternoon of each of days 0-6 post partum. The levels were comparable to those found on the afternoon of pro-oestrus in cyclic hamsters and could be blocked by administration of sodium phenobarbitone at 13.00 h. Similar afternoon surges of LH were not observed during dioestrus. In the morning, the LH levels were significantly higher (P smaller 0-001) in the non-suckled dams (95 plus or minus 4 ng/ml) than those in mothers allowed to nurse their young (13 plus or minus 4 ng/ml). In contrast, the levels in the afternoon were unaffected by the suckling stimulus (suckled, 495 plus or minus 76 v. non-suckled, 744 plus or minus 165 ng/ml; P greater than 0-05).
D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D001942:Breast Feeding; D002697:Chloral Hydrate / Q000494:pharmacology; D002940:Circadian Rhythm; D003307:Copulation; D006224:Cricetinae; D004031:Diestrus; D004986:Ether / Q000494:pharmacology; D005260:Female; D007743:Labor, Obstetric / Q000187:drug effects; D007986:Luteinizing Hormone / Q000097:blood*; D007752:Obstetric Labor, Premature; D010424:Pentobarbital / Q000494:pharmacology; D049590:Postpartum Period; D011247:Pregnancy; D011359:Proestrus; D011458:Prostaglandins E / Q000494:pharmacology; D013997:Time Factors
D000777:Anesthetics; D011458:Prostaglandins E; D004986:Ether; D002697:Chloral Hydrate; D007986:Luteinizing Hormone; D010424:Pentobarbital