Diurnal rhythms in gonadotropins and progesterone in lactating and photoperiod induced acyclic hamsters

Journal Article · Mon Dec 01 04:00:00 EST 1975 · Biol. Reprod.; (United States)

DOI:https://doi.org/10.1095/biolreprod13.5.617· OSTI ID:7317168

Bridges, R S; Goldman, B D

Levels of LH, FSH, and progesterone in serum were measured in lactating hamsters and in hamsters in which acyclicity was induced with altered photoperiod. Lactating hamsters were found to have low titers of LH, FSH, and progesterone in serum at 0900 (lights on 0500--1900) on Days 4, 9, 14, and 19 of lactation and increased levels of these hormones at 1600. Levels of LH and FSH in serum at both 0900 and 1600 remained relatively constant throughout lactation. In contrast, levels of progesterone in serum obtained at both 0900 and 1600 sampling times increased as lactation progressed. Ovariectomy on Day 9 of lactation reduced serum levels of progesterone at both 0900 and 1600 and eliminated the afternoon surge in progesterone in animals bled 5 days after surgery. The levels and pattern of LH in serum remained unchanged after ovariectomy in lactating hamsters. However, serum FSH levels in the ovariectomized, lactating animals were elevated at both 0900 and 1600 when compared to levels present in intact, lactating hamsters bled at the same times. Females which were acyclic due to altered photoperiod displayed similar patterns of LH, FSH, and progesterone in serum. Levels of LH, FSH, and progesterone in serum were low at 1000 (lights on 0500--1500) and were increased 2 to 10 fold at 1500. Ovariectomy was followed by lower progesterone levels in serum at 1000 and 1500 and eliminated the afternoon rise of this hormone. Serum levels of LH were unaffected by ovariectomy. As in lactating hamsters, levels of FSH in serum were elevated 3--4 days following ovariectomy at both bleeding times, but the levels were higher at 1500. These results indicate that acyclicity induced by lactation or exposure to a short photoperiod is characterized by similar diurnal patterns of circulating hormones in the hamster.

• Research Organization: Univ. of Connecticut, Storrs
• OSTI ID: 7317168
• Journal Information: Biol. Reprod.; (United States), Journal Name: Biol. Reprod.; (United States) Vol. 13:5; ISSN BIREB
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ANIMALS
BLOOD SERUM
DAILY VARIATIONS
FSH
GONADOTROPINS
HAMSTERS
HORMONES
ISOTOPE APPLICATIONS
KETONES
LH
MAMMALS
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PITUITARY HORMONES
PREGNANES
PROGESTERONE
RADIOASSAY
RADIOIMMUNOASSAY
RODENTS
STEROID HORMONES
STEROIDS
TRACER TECHNIQUES
VARIATIONS
VERTEBRATES