Participation of glucocorticoids in the regulation of plasma LH levels in the male domestic duck (Anas platyrhynchos L.).

Adult male domestic ducks were treated in autumn for 14 consecutive days with either (i) long-acting ACTH (20 IU/day), (ii) corticosterone (25 mg/day), (iii) dexamethasone (0.25 mg/day) or (iv) a control solution. Blood samples were obtained from all birds after 1, 3, 7 and 14 injections of hormones; on each of these occasions, a sample was obtained 3 times during the day. The 3 hormonal treatments induced a marked and transient (observed on the 3rd and 7th, but not on the 1st and 14th days of injection) elevation of the LH plasma levels. This increase was not associated with any alteration of the testosterone plasma levels. The results are discussed in view of our knowledge of the influence of adrenal hormones on the pituitary-gonadal axis.