Plasma concentrations of LH, progesterone, and corticosterone during ACTH- and corticosterone-induced ovulation in the hen ( Gallus domesticus)

Abstract

Corticosterone and ACTH were injected either 6 hr after ovulation of a mid-sequence follicle or 14 hr before the first ovulation of a sequence. Ovulation was not induced by injection of either hormone given 6 hr after ovulation but 12 of 15 hens injected with 1.5 mg of corticosterone and 6 of 13 hens injected with 10 IU of ACTH given 14 hr before the first ovulation of a sequence ovulated within 8 hr. Injection of either ACTH or corticosterone 6 hr after a mid-sequence ovulation was followed by a decline in the concentration of LH, whereas the concentration of progesterone remained stable. The concentration of both LH and progesterone was increased during 1–5 hr before an ovulation induced by an injection of either ACTH or corticosterone given 14 hr before the first ovulation of a sequence. The increase in the plasma concentration of corticosterone which was required to induced ovulation with either hormone was identical and not within the normal physiological range. It was concluded that the ovulation-inducing action of ACTH was mediated by its effect on corticosterone production and/or secretion by the adrenal gland, that a mature follicle capable of progesterone secretion must exist within the ovary before an injection of either ACTH or corticosterone can induce ovulation, and that the ovary is the most probable target tissue for corticosterone in the context of its ovulation-inducing action.