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Diurnal changes in plasma prolactin during the last one third of pregnancy in the baboon
Author(s) -
Nguyen Tuan,
Diveky Lubomir,
Fedirko Bohdan,
Kowalski Wlodzimeirz,
Mehendale Ramkrishna,
Pak Sok Cheon,
Parsons Michael,
Wilson Laird
Publication year - 1999
Publication title -
american journal of primatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.988
H-Index - 81
eISSN - 1098-2345
pISSN - 0275-2565
DOI - 10.1002/(sici)1098-2345(1999)47:3<231::aid-ajp5>3.0.co;2-f
Subject(s) - baboon , prolactin , morning , evening , endocrinology , medicine , pregnancy , radioimmunoassay , circadian rhythm , blood sampling , diurnal temperature variation , gestation , biology , hormone , physics , atmospheric sciences , astronomy , geology , genetics
Previous studies in our laboratory revealed that daily plasma prolactin (Prl) levels were higher in the evening than in the morning in the pregnant baboon suggesting a diurnal variation. The goal of this study was to examine in more detail the diurnal alterations in plasma Prl levels. A tethered pregnant baboon model was utilized for these studies. Hourly venous blood samples were taken from 0700 to 2400 hr (n=10) or until 0700 hr the following day (n=5). The studies were performed at various days of pregnancy from day 135 until delivery. Plasma samples were analyzed for Prl by radioimmunoassay. A surge in plasma Prl was detected, starting around 1500 to 1600 hr and lasting for 3 to 5 hr. The surge occurred before the lights went off in the colony (1800 hr). Baseline Prl levels were higher in animals < 15 days before delivery compared to those > 15 days before delivery ( P < 0.05). In contrast, no differences were found in the average peak Prl values between these two groups of animals. In summary, in the pregnant baboon during the last one‐third of pregnancy plasma Prl surges, beginning around 1500 to 1600 hr and lasting for 3 to 5 hr. Less than 15 days before delivery the mean baseline Prl levels are higher compared to animals greater than 15 days before delivery. Am. J. Primatol. 47:231–239, 1999. © 1999 Wiley‐Liss, Inc.