Dietary arginine deprivation and delayed puberty in the female rat

Dietary arginine deprivation was found to delay puberty in the female rat. Physiological pinealectomy by exposing to constant light suggests this gland is not involved in this delay. Compensatory ovarian hypertrophy (COH) was used to test the hypothalamic sensitivity to negative steroid feedback. COH occurred in hemiovariectomized immature rats ad libitum fed the control or arginine-deficient diet but failed to occur in hemiovariectomized, underfed, growth-matched control rats, which suggests that feed restriction and arginine deficiency do not exert identical effects on the hypothalamic-pituitary-gonadal axis. Puberty, as defined by vaginal opening, first ovulation and the initiation of estrous cycles, was advanced by a week in the immature female rat fed a control diet after treatment with estradiol benzoate, 0.05 microgram/(100 g body weight X day) starting at 26 days of age. The time of first estrus and the first ovulation was not advanced in arginine-deficient rats by the same dosage of estrogen when administration began at 26 days of age. Treatment at an older age (40 or 54 days) or with a higher dosage [0.25 microgram/(100 g body weight X day)] at 26 days of age did advance puberty. The failure of estrogen to induce a vaginal cyclicity suggests an insufficient amount of endogenous estrogen to trigger a gonadotropin surge to cause the onset of puberty in the rat fed an arginine-deficient diet.