Impact of polychlorinated naphthalenes (PCNs) in juvenile Baltic salmon, Salmo salar: evaluation of estrogenic effects, development, and CYP1A induction.
Juvenile Baltic salmon, Salmo salar, were fed commercial salmon food contaminated with different concentrations of polychlorinated naphthalenes (PCNs; 0.1, 1, 2, or 10 microg PCN/g food). Among other effects, possible estrogenic impact caused by PCNs were evaluated. Fish were therefore fed a diet contaminated with 17beta-estradiol (E2; 0.94 or 9.4 microg E2/g food), as a positive control. After 8, 13, 17, and 41 weeks, sampling took place. Growth, liver somatic index (LSI), EROD activity, and vitellogenin content in blood plasma were measured along with morphological studies of gonads and chemical analyses to determine the effects caused by PCNs. Exposure to PCNs did not seem to have any effects on body weight gain, since the group fed the high dose followed the growth in the control group during the entirely experimental period. After 41 weeks of exposure the groups fed 2 and 10 microg PCN/g food had significantly lower LSIs compared with the control, indicating liver toxic effects of PCNs. Furthermore, a dose-dependent induction of EROD activity was found. At week 41, the control group had an activity of 4.9 +/- 4.8 pmol/mg prot/min, whereas it was between 69 +/- 21 and 720 +/- 370 pmol/mg prot/min in the exposed groups, respectively. Examination of gonadal morphology showed that PCNs also had negative effects on ovaries in Baltic salmon, including delayed development. The distribution between females and males, gonadal morphology, and vitellogenin content in blood plasma did, however, indicate that PCNs are not capable of causing effects similar to E2 or xenoestrogens. Exposure to both of the concentrations of E2 resulted in decreased body weight gain, increased LSI, and feminization of the gonads. E2 did, however, not induce any EROD activity.
Akerblom
N
N
Department of Pathology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-750 07 Uppsala, Sweden.
Olsson
K
K
Berg
A H
AH
Andersson
P L
PL
Tysklind
M
M
Förlin
L
L
Norrgren
L
L
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism*; D004032:Diet; D004790:Enzyme Induction / Q000187:drug effects; D004967:Estrogens / Q000008:administration & dosage; D005260:Female; D006066:Gonads / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006843:Hydrocarbons, Chlorinated / Q000633:toxicity*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D009281:Naphthalenes / Q000633:toxicity*; D012474:Salmon / Q000097:blood / Q000254:growth & development / Q000378:metabolism*; D014819:Vitellogenins / Q000097:blood
D004967:Estrogens; D006843:Hydrocarbons, Chlorinated; D009281:Naphthalenes; D014819:Vitellogenins; D019363:Cytochrome P-450 CYP1A1