Daily infusion of corticosterone and reproductive function in the domestic hen ( Gallus domesticus)

Abstract

The purpose of this study was to examine the effect of the daily infusion of corticosterone on reproductive function in the laying hen and to determine the relationship between the cyclic pattern of plasma concentrations of corticosterone on the open-period for the preovulatory release of LH. An exogenous rhythm of plasma levels of corticosterone was generated using an osmotic pump. Corticosterone was infused subcutaneously into laying hens at rates of 5, 10, 15 or 30 μg/hr for a duration of 10hr beginning with the onset of darkness or at 15 μg/hr for 4hr, or continuously at 30 μg/hr. Daily infusions greater than 15 μg/hr and the continuous infusion resulted in cessation of ovulation, ovarian and oviductal regression, hyperphagia, and elevated levels of plasma corticosterone compared to that observed in control hens. The hens which were infused with 5 or 10 μg/hr of corticosterone maintained normal reproductive function with plasma concentrations of corticosterone that were approximately the same as those in the control hens. The effect of infusing 10 μg/hr of corticosterone on the open-period for the preovulatory release of LH was determined under constant light. No significant changes were observed in the frequency distribution of the times of oviposition when hens were infused with 10 μg/hr of corticosterone for 12hr from 9:00 to 21:00hr or 21:00 to 9:00hr each day. The results of this study indicate that a circadian rhythm in plasma levels of corticosterone cannot drive the open-period under constant illumination and that the effects of the infusion of corticosterone on reproductive function and feed intake are dependent upon the dose and duration of infusion.