Investigation of de novo cholesterol synthetic capacity in the gonads of goldfish (Carassius auratus) exposed to the phytosterol beta-sitosterol

Abstract

Total and intra-mitochondrial gonadal cholesterol concentrations are decreased in fish exposed to the phytoestrogen beta-sitosterol (beta-sit). The present study examined the potential for beta-sit to disrupt de novo cholesterol synthesis in the gonads of goldfish exposed to 200 microgram/g beta-sit and 10 microgram/g 17beta-estradiol (E2; estrogenic control) by intra-peritoneal Silastic ® implants for 21 days. The de novo cholesterol synthetic capacity was estimated by incubating gonadal tissue with 14C-acetate for a period of 18 hours, followed by chloroform/methanol lipid extraction and thin layer chromatography (TLC) lipid separation. Lipid classes were confirmed using infrared spectroscopy. Plasma testosterone (T) and total cholesterol concentration were measured and gonadosomatic index (GSI) was calculated. Plasma T was significantly reduced in male beta-sit-treated fish compared to control and E2-treated fish (p < 0.001). 14C-Acetate incorporation into cholesterol and cholesterol esters was not significantly different among treatment groups for male and female fish, however, 14C-enrichment was higher than expected in both triglycerides (TG) and free fatty acids (FFA). FFA incorporation was significantly higher in male control fish than either beta-sit or E2 treatments (p = 0.005). Plasma cholesterol concentration was significantly increased in the male beta-sit treatment group compared to controls (p = 0.027). These results indicate gonadal de novo cholesterol biosynthetic capacity is not disrupted by betasit or E2 treatment in early recrudescing male or female goldfish, while plasma cholesterol and steroid concentrations are sensitive to beta-sit exposure.

Lipid and Protein Content in Rainbow Trout in Relation to Gonadal Growth

“…Triglycerides have been found to be the main source of energy storage in fish and are stored in the liver and muscles. Cholesterol acts as a precursor to steroid hormones and also performs several important cellular functions in the testes (Scott, 1987;Sharpe et al, 2006). Lipids, such as phospholipids and cholesterol, are also primary units of cellular and subcellular membranes, and necessary for cellular differentiation (Schiopu et al, 2006;Liu et al, 2007).…”

Monocrotophos pesticide affects synthesis and conversion of sex steroids through multiple targets in male goldfish (Carassius auratus)

“…In theory, the process of sex hormone synthesis provides numerous potential targets for MCP pesticide. First, cholesterol serves as precursor to all steroid hormones, and some xenobiotics disturbed the synthesis of sex hormones by affecting cholesterol levels 6 – 8 . Second, the synthesis of sex hormones starts only when cholesterol is transported to the inner mitochondrial membrane.…”

Influence of Dietary Feeding of Low Monomer Content Grape Seed Extract on Vitellogenin Production and Cholesterol Levels in Goldfish, Carassius auratus

“…Because phytosterols have been shown to affect lipid dynamics in both mammals and fish , , we have also investigated the effect of GSE on hepatic cholesterol level in a fish model. In goldfish ( C. auratus ), hepatic cholesterol concentrations increase following exposure to E2 but not to a phytoestrogens such as β-sitosterol.…”