Basic neuroendocrine events before puberty in cattle, sheep and pigs

Neuroendocrine events before puberty are compared in male and female cattle, sheep and pigs. The patterns of secretion of gonadotrophin, the age-related LH responses to castration or LH-RH administration and the effects of prolonged steroid treatment give information about the maturity of the hypothalamic-pituitary axis. It appears that in all three species the mechanisms involved in the expression of puberty are progressive rather than abrupt events. Some original contributions reported here, such as age-related changes in plasma levels and pulses of LH in the gilt, and the variations in pituitary cytosol receptors to 5a-dihydrotestosterone and oestradiol-17I3 in the male lamb support this contention. Finally, this brief review of the neuroendocrine events known to occur before puberty in three domestic mammals underlines numerous missing links in our understanding of the prepubertal processes.