PLASMA STEROID AND CORTICOSTEROID LEVELS IN FEMALE PACU PIARACTUS-MESOPOTAMICUS, TELEOSTEI-CHARACIDAE

We report the plasma levels of estradiol-17 beta (E(2)), testosterone (T), 17 alpha-20 beta-dihydroxy-4-pregnen-3-one (17-20P), and cortisol (F) in female pacu during the reproductive cycle (N = 44) and in fema les induced to ovulate with an analogue of luteinizing hormone releasi ng hormone (LHRHa; 10 mu g/kg) (N = 24). The plasma hormone levels wer e determined by validated radioimmunoassays. Females sampled during th e reproductive cycle were grouped into 4 gonadal stages: resting, earl y maturation, advanced maturation and regression. The calculated gonad osomatic index varied from 0.5 +/- 0.1% in resting stage to 8.1 +/- 0. 6% in advanced maturation stage. The E(2) and T values were highest du ring the early maturation stage (E(2) = 2172 +/- 7.1 pg/ml; T = 412 +/ - 58 pg/ml) and the F values were highest during the advanced maturati on stage (132 +/- 5 ng/ml). Females induced to ovulate by LHRHa inject ion were sampled at 0, 6, and 12 h after injection of LHRHa. Two addit ional groups were sampled at ovulation and 24 h after ovulation. The E (2) values were highest at 6 h (2917 +/- 65 pg/ml). The T and F values were highest at ovulation (T = 3498 +/- 77 pg/ml; F = 387 +/- 16 ng/m l) and 17-20P was detected only at ovulation (2163 +/- 80 pg/ml).