Radioimmunoassay for male canine plasma 4-androstenedione, testosterone and 5α-dihydrotestosterone

The radioimmunoassay for the simultaneous measurement of 4-androstenedione (A), testosterone (T), and 5α-dihydrotestosterone (DHT) in canine plasma was carried out. The assay for these 3 plasma steroids showed to be satisfactorily sensitive, specific, and accurate. The plasma steroid levels of peripheral and spermary vein plasma collected from 15 male dogs were (A) 0.86 +-0.75, (T) 1.19+-1.05 and (DHT) 0.30+-0.25 in peripheral vein, and (A) 30.2+-18.5, (T) 157+-98 and (DHT) 17.5+-10.7 in spermary vein, respectively (ng/ml and SD). Analysing these data, the significant correlation between two vein plasma levels was suggested. In order to estimate the normal or common diurnal variations of these plasma steroid levels in male dogs, 5 animals were employed, and their peripheral plasma samples were collected every an hour or two, throughout 24 hour period. In these data, the frequent intermittent peaks of plasma steroids were observed in each dog, and these seem to be their own diurnal changes. It was concluded that the peripheral plasma levels of A, T, and DHT were correlated to those in spermary vein, and these steroid levels were seemingly reflected by the episodic secretion from the gonads. (Kobatake, H.)