Plasma and pituitary concentrations of gonadotropins (FSH and LH) in minkewhales (Balaenoptera acutorostrata) during the feeding season

This study investigated plasma and pituitary concentrations of follicle-sti mulating hormone (FSH) and luteinizing hormone (LH) and steroid hormones (p rogesterone: P-4, testosterone:T, estradiol-17 beta: E-2) by enzyme-immunoa ssay (EIA) in minke whales (Balaenoptera acutorostrata) captured during the feeding season (December to March) in the Antarctic Ocean. Plasma FSH and LH levels in female minke whales were higher (P <0.05) than in male whales. Although the pituitary weight was not significantly different between male and female whales, pituitary FSH and LH levels were higher in females than in males (P<0.01) and mature whales than immature whales (P<0.05). Plasma levels of FSH, T and E-2 were not significantly different between immature and mature male whales, but plasma LH and pituitary FSH and LH levels were higher (P<0.05) in mature than in immature whales. In both immature and mat ure whales regardless of gender, pituitary FSH and LH levels were correlate d significantly (r=0.69: P<0.01). In mature male whales, plasma T and E, le vels (r=0.60: P<0.01), and testis weight and plasma T levels (r=0.46: P <0. 05) were correlated. In immature female whales, plasma FSH and LH levels we re highly correlated (r=0.68: P<0.001), but were not for mature female whal es. The results show that gender and maturity influence gonadal and pituita ry function of minke whales during the feeding season. (C) 2001 by Elsevier Science Inc.