Influence of Age, Strain and Season on Orcadian Periodicity of Pituitary, Gonadal and Adrenal Hormones in the Serum of Male Laboratory Rats

Publisher Website
Google Scholar
Abstract
The influence of age, strain and season on the circadian pattern of serum levels of LH [luteinizing hormone], FSH, prolactin, androgens and croticosterone was studied in 5 groups of male laboratory rats. Significant 24-h periodicity was observed for serum levels of corticosterone in all 5 groups, for androgen levels in 4, for prolactin levels in 3, for LH levels in 2 and for FSH levels in 1 group of rats. There were significant influences of age, strain and season on the temporal patterns and/or on 24-h mean serum hormone levels. Some of the disagreements on existence or nonexistence of circadian rhythms and on rhythm patterns in serum hormone levels may be explained by the fact that animals of different ages or strains was used or that experiments were performed at different times of the year.