Effect of testosterone on binding of insulin-like growth factor-I (IGF-I) and IGF-II in growing antlers of fallow deer (Dama dama)

Testosterone regulation of antler growth may be via the insulin-like growth factors (IGFs). Using histological autoradiography we have measured the specific binding of IGF-I and IGF-II to antler sections during normal Won th and during the maturation which follows testosterone treatment of adult fallow deer. In antlers from 20 to 100 days following casting, IGF-I binding was constant within each histological region until 80 days. Between this time and 100 days there was decreased binding to chondrocytes (P less than or equal to 0.01) and increased binding to the reserve mesenchyme/perichondrium (P less than or equal to 0.001). Following testosterone treatment, IGF-I binding declined in dermis (P less than or equal to 0.05), reserve mesenchyme/perichondrium (P less than or equal to 0.05), and chondroblasts (P less than or equal to 0.01). Specific binding of IGF-II showed no change during normal or testosterone-stimulated growth. In conclusion, the regulation of antler maturation bq testosterone mag include IGF action, probably via the Type 1 IGF receptor.