Serum Profiles of LH, FSH and Prolactin from 10 Weeks of Age until Puberty in Gilts2

Abstract

To characterize the secretory patterns of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) during prepubertal development of the gilt, blood samples were collected at 20-min intervals for 4 h once a week from four littermate gilts 10 to 18 wk of age and from another group of four littermate gilts 19 to 25 wk of age. Puberty occurred in the latter group during wk 25. Serum concentrations of LH, FSH and PRL were averaged for each 4-h sampling period within each gilt, and any single value greater than one standard deviation above the mean for that period was identified as a secretory spike. Mean LH was greater at 16 wk of age than during wk 11, 12 and 13, and serum LH levels were higher at 25 than 22 wk of age. Frequency and magnitude of LH spikes were greatest at 16 wk in the group of gilts 10 to 18 wk of age, but magnitude of LH spikes did not change from 19 to 25 wk. The frequency of FSH secretory spikes did not change in gilts from 10 to 25 wk of age. No changes in mean serum concentrations of PRL, frequency of PRL spikes and magnitude of PRL spikes were observed during prepubertal development. Spikes of FSH and PRL occurred with more than random synchrony throughout the study. Spikes of LH and FSH or LH and PRL were highly synchronized during early prepubertal development (10 to 18 wk), but less synchronized in gilts 19 to 25 wk of age.

Relaxin protein and gene expression in ovarian follicles of immature pigs

“…In women, baboons and monkeys, plasma relaxin also increases after human chorionic gonadotropin (hCG) administration (Quagliarello et al 1980, Castracane et al 1983, Ottobre et al 1984. Although cyclic or exogenous gonadotropins were absent in the present study, we cannot rule out the possibility that follicular relaxin production is influenced by the low circulating levels of gonadotropins reported in prepubertal gilts (Colenbrander et al 1982, Diekman et al 1983, Grieger et al 1986.…”

The Comparative Physiological Development of the Reproductive and Adrenal Axis of the Gilt From Weaning to Puberty

“…Diekman et al (1983) from 10 to 25 wk of age and by Camous et al (1985) from2 to 28 wk of age. It has previously been suggested that the transitory increase in LH Plasma profiles of estradiol as observed in this study differ markedly from the pattern of urinary estrone excretion as reported by Camous et al (1985).…”

Maturational changes in gonadotrophin secretion: the LH response to realimentation and a nocturnal increment in LH secretion of feed-restricted prepubertal gilts

“…However, these authors reported increased prepubertal FSH secretion, which began to decline only at 125 days of age (equivalent to the second weight group of the present study). A decline in FSH secretion from as early as 70 days of age has been reported in gilts (Diekman et al, 1983) …”