Endocrine Abstracts

The secondary sexual characteristics such as a neck mane and antlers seen in the male red deer are unusual in that they are produced on an annual basis and are linked to the breeding season. This cycle is highly controlled and the development of these characteristics coincides with changes in plasma levels of testosterone and IGF-1. We have previously shown that the expression of the androgen receptor in the hair follicle cells of the neck mane are only present during the breeding season when testosterone levels are high (Thornton MJ et al, J Endocrinol, 168: 401-8, 2001). In this study we have investigated whether the expression of steroidogenic enzymes is also influenced by changes in plasma levels of these hormones. Therefore, we have used immunohistochemistry to investigate the expression of 3beta-hydroxsteroid dehydrogenase (3beta-HSD) and type 5 17beta-hydroxsteroid dehydrogenase (17beta-HSD) in the skin of red deer during both the breeding and non-breeding season.

During the non-breeding season, apart from the stratum corneum, strong expression of 3beta-HSD was seen in the cytoplasm of the cells of all layers of the epidermis. 3beta-HSD was also expressed in the hair follicle and to a lesser extent in the sebaceous gland. However, during the breeding season neither the epidermis nor sebaceous gland demonstrated any immunoreactivity for 3beta-HSD, while the hair follicle only showed weak immunoreactivity. The expression of type 5 17beta-HSD was similar to that of 3beta-HSD, apart from the sebaceous gland which also expressed type 5 17beta-HSD in the height of the breeding season.

These results suggest that plasma androgen and/or IGF-1 levels may be important in modulating the expression of some steroidogenic enzymes in skin. Further studies using cultured skin and hair follicle cells may help to identify factors that are important in modulating the expression of these enzymes.