K. Kinnberg et al., Effects of nonylphenol and 17 beta-estradiol on vitellogenin synthesis andtestis morphology in male platyfish Xiphophorus maculatus, J EXP BIOL, 203(2), 2000, pp. 171-181
Nonylphenol has been found to exert estrogenic effects in fish and may infl
uence the fertility of male fish. In the present study, the effects of nony
lphenol and 17 beta-estradiol on vitellogenin synthesis and testis morpholo
gy in platyfish Xiphophorus maculatus were investigated. Vitellogenin was o
bserved in the plasma of all fish exposed to nonylphenol or 17 beta-estradi
ol. Exposure to 17 beta-estradiol resulted in a significant reduction in th
e gonadosomatic index. A tendency for a dose-dependent reduction in the gon
adosomatic index in the nonylphenol exposed groups was observed. Histologic
al examination revealed dose-dependent effects of nonylphenol on the testis
structure. The testes of control fish contained numerous cysts with sperma
togenetic cells. The testes of fish exposed to nonylphenol or 17 beta-estra
diol showed a decrease in the number of cysts concomitant with an increase
in the amount of hypertrophied Sertoli cells present. Formation of spermato
zeugmata is compulsory for this species, but free spermatozoa were observed
in the efferent ducts of the treated fish. The study indicates that nonylp
henol has estrogenic potency, and that both nonylphenol and 17 beta-estradi
ol have marked effects on the testis morphology of X. maculatus. The ambien
t concentration of nonylphenol was measured by high pressure liquid chromat
ography during the experiment. The measurements revealed that the actual co
ncentrations of nonylphenol in the water were about 30-40 % of the nominal
concentrations.