Effects of Corticosterone Treatment on Puberty in Female Rats

Abstract

To study the role of excess corticosterone on regulating puberty onset without the added component of a stressful route of administration, corticosterone was made available ad lib in the drinking water beginning at weaning age (22 days of age). The lowest dose (16 .mu.g of corticosterone/ml of 4% ethanol in tap water) did not delay puberty but did suppress the normal peak of corticosterone at 1600 h. The next dose (24 .mu.g) also suppressed the evening corticosterone peak. In these rats vaginal opening was normal but ovulation was delayed in comparison to controls given 4% ethanol in tap water or tap water alone. Growth rates in the rats given 16 or 24 .mu.g were normal. The 2 high concentrations (160 and 240 .mu.g of corticosterone/ml of 4% ethanol in tap water) delayed vaginal opening and ovulation, produced high levels of corticosterone in the blood at 0800 and 2300 h and a depression of corticosterone at 1600 h, and were associated with significant growth retardation. A normal adrenal rhythm is not required for puberty onset and the ability of exogenous corticosterone to delay puberty onset can be mediated through routes other than growth retardation alone.