The Effect of Photoperiodic Conditions on GnRH/LH Secretion in Ewes

Overview

Journal Animals (Basel)

Date 2022 Feb 15

PMID 35158608

Authors

Kamila Kopycinska

Karolina Wojtulewicz

Andrzej Przemyslaw Herman

Dorota Tomaszewska-Zaremba

Affiliations

Soon will be listed here.

Abstract

Secretion of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) displays a circadian pattern. Data concerning differences in daily GnRH/LH secretion during different seasons in sheep are fragmentary. The aim of the study was to determine day/night differences in GnRH/LH secretion in the follicular phase and in the anestrous ewes. The studies were performed on Blackhead ewes ( = 24). Ewes from each season were divided into two groups of six animals (day and night group). The animals were euthanized 5 h after sunset or 5 h after sunrise and blood was taken to determine LH and melatonin concentrations. In the hypothalamus, the expression of GnRH and gonadotropin releasing hormone receptor (GnRHR) was determined. In the anterior pituitary, the expression of mRNA encoding subunit β of LH (LHβ) and GnRHR was assayed. Our study showed that GnRH/LH secretion is subject to diurnal and seasonal changes. The observed reduction in LH release, a few hours after the sunset, seems to be universal for both the anestrus and follicular phase, when the processes occurring at the hypothalamus are more equivocal. It could be concluded that the nocturnal suppression of LH secretion in follicular phase ewes may be a mechanism moving the LH surge to the early morning.

Citing Articles

Influence of Acute Inflammation on the Expression of Clock Genes in the Ovine Pars Tuberalis Under Different Photoperiodic Conditions.

Wojtulewicz K, Tomczyk M, Wojcik M, Antushevich H, Bochenek J, Herman A Int J Mol Sci. 2024; 25(21).

PMID: 39519024 PMC: 11546426. DOI: 10.3390/ijms252111471.

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