Plasma steroid profiles in male and female mudpuppies, Necturus maculosus (Rafinesque)

Plasma steroid profiles of healthy adult male and female mudpuppies, Necturus maculosus Rafinesque, were measured in animals sampled from November–June. Steroids in ether extracted plasma were analyzed directly by radioimmunoassay (RIA) for progesterone (P), total androgens, and total estrogens, or after Celite-ethylene glycol column chromatography for P, dihydrotestosterone (DHT), testosterone (T), estrone (E 1), and estradiol-17β (E 2). Steroid levels in both sexes were high compared to other vertebrates (10- to 100-fold greater), and highly variable at all times of the year. Comparison of the steroid profiles of males and females showed no qualitative differences; howeve, titers of all steroids (in ng/ml) were higher in males. Progesterone (P) ranged from 2.0–64.0, dihydrotestosterone (DHT) from 2.0–133, testosterone (T) from 4.0–202, estrone (E 1) from N.D. to 1.87, and estradiol (E 2) from 2.0–9.85 in adult males. In adult female Necturus, P ranged from N.D. to 15.5, DHT from 2.9–11.4, T from 1.5–8.3, and E 2 from −0.4–6.35. E 1 was not detectable. No clear seasonal variations in steroid titers or gonadal structure were observed although holding conditions at 5–8° did not approximate those in nature.