EFFECT OF Α-Melanocyte-Stimulating HORMONE AND TESTOSTERONE ON CUTANEOUS AND MODIFIED SEBACEOUS GLANDS IN THE RAT

Abstract

The effects of alpha-MSH and testosterone propionate on sebum secretion, sebaceous gland volume, dermal lipogenesis, and preputial gland weight and lipogenesis were examined in hypophysectomized rats. Hypophysectomy reduced sebum secretion, sebaceous and preputial gland size, and dermal and preputial gland lipogenesis. The greatest effects were seen on the biosynthesis of wax esters and squalene. Testosterone propionate (TP) increased sebum secretion, sebaceous gland volume and preputial gland weight and lipogenic activity, but had no significant effect on the pattern of lipid labelling. alpha-MSH had no effect on sebaceous or preputial gland size, but increased sebum secretion and dermal lipogenesis, especially wax ester biosynthesis. When given together TP and alpha-MSH had a synergistic effect on sebum secretion and on dermal and preputial gland lipogenesis, and the pattern of lipid labelling was shifted towards normal. TP and alpha-MSH also showed synergism in increasing preputial gland weight, but together they had no greater effect on sebaceous gland volume than that achieved with TP alone. These results suggest that TP and alpha-MSH have different actions on the sebaceous glands with alpha-MSH acting predominantly on lipogenesis and TP on cellualr proliferation and turnover leading to an increase in gland size. Preputial glands differ from cutaneous sebaceous glands in their response to alpha-MSH and androgen which could be a reflection of their more specilized function.

An update on the role of the sebaceous gland in the pathogenesis of acne

“…α-Melanocytestimulating hormone (α-MSH) has been demonstrated to act as a modulator of the rat preputial gland, a specialised sebaceous gland-like structure of rodents. 62 The presence of both MC-1R and MC-5R which bind α-MSH were detected in primary cell cultures of facial human sebocytes. The expression of MC-5R is weaker than that of MC1-R but it has been shown to be a marker of human sebocyte differentiation, since it is expressed in differentiated, lipid-containing sebocytes only.…”

Role of FGFR2-signaling in the pathogenesis of acne

“…In hypophysectomized and castrated rats the reduction of sebaceous lipids was fully restored by concomitant administration of α-MSH and testosterone. 116 In a primary human sebocyte culture system it has been reported that α-MSH can stimulate sebocyte differentiation, sebaceous lipid production and expression of MC5R. 117,118 Thus, evidence is provided demonstrating that α-MSH signaling via MC5R act on a common pathway with androgen-dependent expression of MC5R by induction of the signaling cascade via androgen→FGF7/FGF10→FGFR2b→Shh→Gli→MC5R-expression.…”

Lack of stearoyl-CoA desaturase-1 function induces a palmitoyl-CoA Δ6 desaturase and represses the stearoyl-CoA desaturase-3 gene in the preputial glands of the mouse

“…The preputial glands (PG) are large sebaceous glands, rich in wax esters, triglycerides, and alkyl-2,3-diacylglycerols and are believed to play a role in behavioral interactions through the release of pheromones (9). In humans, the PG is located in the corona glandis and prepuce and secretes smegma preputii.…”