Effects of a phytosterol mixture on male fish plasma lipoprotein fractions and testis P450scc activity.
Plant sterols (phytosterols) have been identified as one potential source of reproductive effects in fish living downstream of pulp mills. beta-Sitosterol, the predominant plant sterol in pulp mill effluent, has previously been shown to decrease plasma sex steroid and cholesterol levels and in vitro gonadal steroid production in fish. In this study, male brook trout (Salvelinus fontinalis) and goldfish (Carassius auratus) were exposed to a phytosterol mixture (72% beta-sitosterol) via Silastic intraperitoneal implants to help elucidate the mechanisms of action of phytosterols on steroid depression. As cholesterol is exogenously supplied for gonadal steroidogenesis, changes in plasma cholesterol fractions were examined. In male brook trout, low-density lipoprotein cholesterol and triglyceride levels decreased significantly, 43 and 50%, respectively, in phytosterol-treated fish. It is improbable, however, that these decreases are linked to depressed gonadal steroidogenesis in fish. The activity of P450scc, which converts cholesterol to pregnenolone (the first step in the steroidogenic pathway), was not affected in testis mitochondria isolated from brook trout or goldfish. Further investigation of the mechanisms of action of phytosterols is required.
Gilman
Christine I
CI
Department of Biology and Canadian Rivers Institute, University of New Brunswick (Saint John), Saint John, New Brunswick, Canada E2L 4L5.
Leusch
Frederic D L
FD
Breckenridge
W Carl
WC
MacLatchy
Deborah L
DL
D000818:Animals; D002784:Cholesterol / Q000097:blood; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000187:drug effects* / Q000378:metabolism; D008078:Cholesterol, LDL / Q000097:blood / Q000187:drug effects; D004781:Environmental Exposure; D006054:Goldfish / Q000378:metabolism*; D007220:Industrial Waste; D008074:Lipoproteins / Q000097:blood / Q000187:drug effects*; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology; D010840:Phytosterols / Q000493:pharmacokinetics / Q000633:toxicity*; D011897:Random Allocation; D012098:Reproduction / Q000187:drug effects; D012855:Sitosterols / Q000633:toxicity; D013737:Testis / Q000187:drug effects / Q000201:enzymology*; D014280:Triglycerides / Q000097:blood; D014337:Trout / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D008078:Cholesterol, LDL; D007220:Industrial Waste; D008074:Lipoproteins; D010840:Phytosterols; D012855:Sitosterols; D014280:Triglycerides; D014874:Water Pollutants, Chemical; C025473:gamma-sitosterol; D002784:Cholesterol; D002786:Cholesterol Side-Chain Cleavage Enzyme