Regional distribution of estradiol receptors in growing antlers

This study of estrogen receptors (ER) was carried out to confirm their presence and to determine their localisation in antler bones. Partially grown antlers were amputated from red deer (Cervus elaphus) stags, the skin removed, and samples taken of periosteum, cartilaginous tissue including perichondrium, and bone. Capacity and binding of free ER in the samples were calculated by Scatchard analysis of data obtained from a radioreceptor assay which utilised [3H]estradiol as tracer. High affinity ER (ka 1.3-3.4 x 10(10)/M) were detected in all tissues sampled with the exception of bone. Receptor capacity ranged from 12-74 fmol/mg protein, ranking the tissues for capacity in the following descending order: periosteum, cartilage, calcified cartilage. These results demonstrate the presence of ER in growing antlers and indicate regional localization of the receptors within these structures. The absence of ER in bone tissue within the antler suggests that the effect of estradiol on stimulation of mineralization in this tissue is indirect and must occur via its binding to the non-calcified tissues of antlers, e.g., periosteum, perichondrium, and cartilage.