VARIATIONS IN PLASMA CONCENTRATIONS OF α-MELANOCYTE-STIMULATING HORMONE DURING THE OESTROUS CYCLE OF THE RAT AND AFTER ADMINISTRATION OF OVARIAN STEROIDS
- 1 January 1981
- journal article
- research article
- Published by Bioscientifica in Journal of Endocrinology
- Vol. 88 (1) , 73-80
- https://doi.org/10.1677/joe.0.0880073
Abstract
Plasma concentrations of α-melanocyte-stimulating hormone (α-MSH) were measured by radioimmunoassay at various times during the oestrous cycle of the rat. Variations in plasma α-MSH concentrations occurred throughout the oestrous cycle. Plasma α-MSH concentrations were low during the day of dioestrus 1 and rose during the evening reaching peak levels at around 02.00 and 06.00 h on dioestrus 2. Plasma α-MSH concentrations then fell and remained low throughout the rest of dioestrus 2. A different pattern was observed during pro-oestrus and oestrus. On those days peak α-MSH concentrations occurred during the morning and persisted until the onset of the dark period at around 17.00 h. Plasma α-MSH concentrations in ovariectomized rats were found to be increased 24 h after administration of a single injection of oestradiol benzoate and at 12 and 36 h after a single injection of progesterone. It is suggested that these ovarian steroids may influence the rhythm in plasma α-MSH concentration that occurs during the oestrous cycle.This publication has 1 reference indexed in Scilit: