The Localization and Characterization of Insulin-Like Growth Factor-I Receptors and the Investigation of Melatonin Receptors on the Hair Follicles of Seasonal and Non-Seasonal Fiber-Producing Goats

The study investigated the presence of IGF-I and melatonin receptors on the hair follicles of cashmere and Angora goats to understand hormonal influences on hair follicle cycles. Using quantitative in vitro autoradiography, IGF-I receptors were found in various parts of the hair follicle and sebaceous glands in both breeds, with dissociation constants (Kd) ranging from 0.1 to 0.9 nm and maximal binding sites (Bmax) between 21.4 and 45.6 fmol/mg tissue. These values did not significantly differ between breeds or sampling times. No melatonin receptors were detected on the hair follicles or associated structures. The presence of IGF-I receptors suggests their involvement in fibre growth and antler velvet development, while melatonin receptors were absent.