Effects of short periods of warm water fl uctuations on reproductive endocrine axis of the pejerrey (Odontesthes bonariensis ) spawning

ELISIO M; CHALDE T; MIRANDA LA

COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. A: COMPARATIVE PHYSIOLOGY.

Elsevier

Lugar: Amsterdan; Año: 2012 vol. 163 p. 47 - 55

0300-9629

The aim of this study was to assess fl uctuations in daily water temperature in Chascomús Lagoon during one year, and to evaluate wheth er the highest temperature recorded during pejerrey spawnin g season can produce an endocrine disruption on brain – pituitary –gonads axis. Fish were subjected to daily temperature fluctuations: 17 °C to 19 °C (reproductive control), 19 °C to 25 °C, and 19 °C to 27 °C. After 8 days, ten fish per treatment were sacri fi ced and gene expression of gonadotropin-r eleasing hormone (GnRH -I, GnRH-II, GnRH-III ), gonadotropin subunits- β (FSH- β, LH-β), glycopr otein hormone- α ( GPH-α), gonad otropin receptors (FSH-R, LH-R ), and gonadal aromatase ( cyp19a1a) was analyzed. Also, plasma levels of sexual steroids and gonadal repro ductive status were studied. Fish exposed to high temperature fluctuations quit spawning, presenting clear signs of gonadal regression. Fish recovered its spawnin g activity 11 weeks after heat treatment. At endoc rine level, GnRH-I and FSH- β in both sexes, LH-β and GPH- α in males and FSH-R, LH-R and cyp19a1a in females decreased signi ficantly in treated fi sh. Also, a strong reduction in plasma sex steroid levels was found for both sexes. This study demons trated that pulses of warm water in natural environment during pejerrey spawnin g season can disrupt all levels of the reproductive axis, impairing reproduction.