Interactions of gonadal steroids, gonadotropins and gonadotropin-releasing hormones in sexual maturation

Abstract

Plasma and pituitary concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in individual male rats pretreated with testosterone and its 5α-reduced metabolites for various lengths of time at various stages of sexual maturation. The degree of androgen induced inhibition of the gonadotropins depended on the maturation of the animals and the administration of synthetic LH-RH could not restore the levels to the pre-androgenblocked periods. The stimulation of LH and FSH due to LH-RH was also dependent on age and time-interval between the treatment with androgen and the collection of samples. The chronic treatment of dihydrotestosterone (DHT) and 3α, 5α-androstanediol (ADIOL) daily from day 1 after birth to day 90 demonstrated extremely variable results. Although release and synthesis of LH was inhibited due to LH, FSH was inhibited only between ages 25 and 40 days. From day 50 onwards FSH in the DHT-treated animals registered higher values. With ADIOL, although LH showed mild inhibitory effects at certain age points, FSH demonstrated stimulating values. Pituitary contents of both LH and FSH were markedly higher in the ADIOL-treated animals than the levels seen in the control group. This significant augmentation of serum and pituitary FSH as well as pituitary LH contents in the pubertal and adult animals with chronic treatment of ADIOL suggests that this metabolite may have an action not shared by the parent compound.