Studies on 5α-androst-16-en-3-one binding to porcine serum, plasma and testicular cytosolic fraction and to human serum

The present study evaluated whether a specific androstenone-binding protein is present in porcine and human serum, and in the cytosolic fraction of porcine testis. The binding of [3H]-androstenone to serum and testicular cytosol was measured in the absence (total binding) and presence (non-specific binding) of unlabelled androstenone. The optimization of the assay is described. As a part of the assay validation, the binding of [3H]-dihydrotestosterone ([3H]-DHT) to porcine and human serum was also examined. As expected, specific binding of [3H]-DHT was detected in human serum, but not in porcine serum. No specific androstenone-binding protein was detected, either in porcine or human serum, or in the cytosolic fraction of porcine testis. The amount of non-specific binding of [3H]-androstenone was slightly lower in porcine serum compared to human serum. Between-animal variations in [3H]-androstenone binding were studied in plasma samples from 15 animals with androstenone concentrations ranging from 1.1 to 23.1 ng/mL. Mean values ± standard deviations of binding in these samples were 15.2 ± 0.9% for total binding and 15.9 ± 0.8% for non-specific bindings. Low between-animal variations indicate that androstenone binding does not affect androstenone accumulation in fat.