EXPRESSION OF THE MELANOCORTIN RECEPTORS MC2-R (ACTH-RECEPTOR) AND MC5-R DURING EMBRYONIC DEVELOPMENT OF OVINE ADRENALS

Abstract

Two melanocortin receptors MC2-R (ACTH-receptor) and MC5-R are expressed in the adult lamb adrenal cortex. In this work, we have studied the time-course of expression of these two receptors during ovine fetal development. MC2-R expression progressively increases from day 60 to day 140 of gestation ( × 3), then more rapidly before parturition and remains constant in the newborn. In contrast, the pattern of MC5-R expression is totally different. A strong increase is observed between days 60 and 120 ( × 7) then followed by a decrease until parturition and after birth. This peak of MC5-R expression precedes that of MC2-R, suggesting that MC5-R might be involved in α-MSH- and / or ACTH-stimulated corticosteroid synthesis during early embryonic life.