Endocrine regulation of pejerrey (Odontesthes bonariensis) spermatogenesis in the wild.

ELISIO M; CHALDE T; MIRANDA LA

Rennes

Congreso; 27th Congress of the European Comparative Endocrinologists; 2014

Society of European Comparative Endocrinologists

Endocrine regulation of pejerrey (Odontesthes bonariensis) spermatogenesis in the wild   Elisio Mariano1, Chalde Tomás2, Miranda Leandro Andrés3   1 INIDEP, Mar del Plata (Buenos Aires, Argentina) 2 CADIC, Ushuaia (Tierra del Fuego, Argentina) 3 IIB-INTECH (CONICET-UNSAM), Chascomús (Buenos Aires, Argentina) melisio@inidep.edu.ar   The endocrine mechanisms that regulate spermatogenesis in fish and their interaction with environmental cues have been poorly studied compared with oogenesis. The aim of this work was to study the spermatogenesis in pejerrey fish under the influence of photoperiod and water temperature fluctuation in a Pampas shallow lake (Chascomús, Buenos Aires, Argentina), evaluating the transcript levels of brain Gnrh variants and cyp19a1b, pituitary Gths subunits, gonadal Gth receptors, and 11-KT plasmatic levels. Males at spermiogenic phase were mainly observed during spring, and also during autumn, under a photoperiod above 11 hs of light and a water temperatures below to 21 ºC. Arrested males were observed in summer (water temperatures above 21 ºC), and some of them were caught during winter (9-10 hs of light). Males at spermatogonial phase were mainly observed in autumn, while most males at meiotic phase were caught in winter (lowest photoperiod and water temperature conditions). Gnrh-I increased in proportion to the testicular development. On the other hand, while gnrh-III showed a significant increase at the spermatogonial phase, cyp19a1b increased significantly during the meiotic phase and remained elevated up to the spermiogenic phase. No significant variation was observed for gnrh-II. At pituitary level, fshb increased progressively up to the meiotic phase, and decreased then during the spermiogenic phase. While gphα fluctuated similarly to fshb, lhb showed no significant variation between the gonadal stages. Gonadal Gth receptors showed a significant increase only during the spermiogenic phase, being this event more evident for lhcgr. Plasma levels of 11-KT increased proportionally to the advance of spermatogenesis up to the meiotic phase and decreased then during spermiogenic phase. Present results suggest that in pejerrey, the spermatocyte production occurs mainly during winter (low temperature and short daylength conditions) through the stimulation of FSH and 11-KT, while spermiation occurs after photoperiod increase, with water temperatures below to 21 ºC, and is related to a rise of gnrh-I, cyp19a1b and lhcgr.