Abstract
Summary
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 libitum in the drinking water beginning at weaning age (22 days of age). The lowest dose (16 μg of corticoster-one/ml of 4% ethanol in tap water) did not delay puberty but did suppress the normal peak of corticosterone at 1600 hr. The next dose (24 μg) 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 μg were normal. The two high concentrations (160 and 240 μg of corticosterone/ml 4% ethanol of in tap water) delayed both vaginal opening and ovulation, produced high levels of corticosterone in the blood at 0800 and 2300 hr and a depression of corticoster-one at 1600 hr, and were associated with significant growth retardation. It is concluded that a normal adrenal rhythm is not required for puberty onset and that the ability of exogenous corticosterone to delay puberty onset can be mediated through routes other than growth retardation alone.
This work was supported by NSF Grant No. 74-21733. Mary Alyce Vornholt and Tim Grinbergs provided expert technical help.
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