Increased sebaceous gland activity in the adult rat after alpha-melanocyte-stimulating hormone treatment during early life.

Sebum secretion was measured in adult female and male rats given alpha-melanocyte stimulating hormone (alpha-MSH) during early life. Daily treatment with 40 microgram alpha-MSH/100 gm body weight for the first 5 weeks of life increased sebum secretion in female and male rats at 8, 11, and 15 weeks of age. A lower dose of alpha-MSH (10 microgram/100 gm body weight) produced similar changes in male but not in female rats. No effect on sebum secretion was found in female and male rats aged between 8-28 weeks when alpha-MSH was given (1) from the day of birth to 3 weeks; (2) 3--5 weeks; (3) 1st and 5th weeks and (4) 7--12 weeks. Apparently alpha-MSH must be given throughout the first 5 weeks of life in order to produce a sustained effect on the sebaceous glands. The fact that males appear to be more sensitive than females, in that they responded to a lower dose of alpha-MSH, may indicate that MSH acts by enhancing the response to androgen. Early alpha-MSH treatment failed to alter the sebaceous gland response to testosterone in adult female and male rats but the possibility that alpha-MSH enhances the action of androgen in early life cannot be ruled out.