Seasonal variations in sperm production and sperm quality in male winter flounder, Pleuronectes americanus: the effects of hypophysectomy, pituitary replacement therapy, and GnRH-A treatment

Citation
B. Shangguan et Lw. Crim, Seasonal variations in sperm production and sperm quality in male winter flounder, Pleuronectes americanus: the effects of hypophysectomy, pituitary replacement therapy, and GnRH-A treatment, MARINE BIOL, 134(1), 1999, pp. 19-27
Citations number
40
Categorie Soggetti
Aquatic Sciences
Journal title
MARINE BIOLOGY
ISSN journal
00253162 → ACNP
Volume
134
Issue
1
Year of publication
1999
Pages
19 - 27
Database
ISI
SICI code
0025-3162(199906)134:1<19:SVISPA>2.0.ZU;2-S
Abstract
The pattern of sperm release and changes in sperm quality were investigated throughout the normal spawning season of male winter flounder, Pleuronecte s americanus (Walbaum), caught in Conception Bay, Newfoundland, Canada in A pril and November 1994. In addition, the impact of hormonal manipulation on sperm production and sperm quality was examined through gonadotropin-relea sing hormone analogue (GnRH-A) treatment, hypophysectomy, and pituitary ext ract injection - pituitary replacement therapy (PRT). While a lengthy perio d of spermiation, lasting similar to 6 months (December to July), can be de tected in some males, the major period for sperm release occurred in May to July in the summer spawning season. The spawning period started with peak levels of plasma testosterone (T) and 11 ketotestosterone (11-KT). By late July sperm production fell rapidly along with a notable deterioration in sp erm motility. While GnRH-A treatment advanced the period of sperm release, and the milt became diluted and increased in volume, the treatment did not increase total sperm output over the spawning season. In hypophysectomized male flounder, by contrast, milt was more concentrated and sperm production declined along with reduced plasma androgen levels during the spawning sea son. Increased plasma T and 11-KT levels in hypophysectomized males followe d PRT in December and January. Moreover, PRT appeared to be responsible for advancement of spermiation in a large number of prespawning males, which r eleased an increased amount of milt. Finally, these studies indicated that both sperm motility and egg fertilization rates remained unchanged after th ese hormonal treatments.