摘要

To illuminate the physiology influence of salinity on spotted sea bass (Lateolabrax maculatus) during its reproductive period, blood physiological responses and steroidogenetic effects during its acclimation from seawater to brackish water or freshwater were studied. The levels of steroid hormones and mRNAs in the pituitary and testis were also evaluated during this period. Results revealed that levels of serum osmolality were significantly reduced in both brackish water and freshwater groups during 1- to 8-days acclimation. The contents of PRLR and GR gene in testis were significantly suppressed during 4-8 days in brackish water and freshwater groups, while PRL gene expressions in pituitary were significantly promoted during 1-2 days in these two groups under salinity acclimation. On the other hand, the maturity status of testes after acclimating in freshwater for 8 days was reduced when compared with those in seawater group. Change trends of serum T, FSH and LH concentrations were diverse in different salinity groups. In addition, decreased AMH and FTZ-F1 mRNA transcripts were observed in testes of spotted sea bass in FW group after 2-day administration. It was worth noting that transcript levels of GTH alpha, FSH beta and LH beta subunits in pituitary increased largely during first 2 days of salinity acclimation in brackish water and FW groups. These results suggested that spotted sea bass were capable of a stress-induced stimulation even salinity change rapidly (8 ppt/12 hr) from 30 parts per thousand to 0 parts per thousand. But decreases in salinity may affect hypothalamus-pituitary-gonad axis of spotted sea bass and had negative effects on its testicular function.