No direct mitogenic effect of sex hormones on antlerogenic cells detected in vitro

Deer pedicles, antecedents of antlers, develop from a specialized periosteu m (antlerogenic periosteum) which overlies the lateral crest of the deer fr ontal bone. The initiation of pedicle growth is triggered by androgen hormo nes. Thus far, it is not known whether pedicle initiation is caused by dire ct stimulation of androgen hormones on the antlerogenic periosteum or wheth er some intermediate mechanisms are necessary. The present study took an in vitro approach to investigate whether sex hormones have direct mitogenic e ffects on primary cultured antlerogenic periosteal cells (antlerogenic cell s). Antlerogenic cells were obtained from two 5-month-old red deer calves. The cells were passaged twice and then treated with testosterone, dihydrote stosterone, and estradiol. The proliferation assays showed that no direct m itogenic effects on the second passage antlerogenic cells could be detected with any of the sex hormone treatments (P > 0.05). Testosterone-binding st udies showed that at the second passage, specific testosterone-binding site s were present in the antlerogenic cells. Therefore, we conclude that andro gens do not have mitogenic effects on antlerogenic cells in vitro. Our resu lts suggest that pedicle formation may not be the result of direct stimulat ion of androgen hormones on antlerogenic tissue. Instead, androgen hormones may only allow the process to proceed by increasing the sensitivity of ant lerogenic cells to mitogens, e.g., some growth factors. (C) 2001 Acidemic P ress.