Vitellogenin

Measurement of contaminants in fish has concentrated on muscle tissue since the aim has generally been to protect the health of the consumer rather than that of the fish. Endocrine tissue such as the gonads has been much more rarely examined, while data for adrenal, thyroid and pituitary levels are virtually non-existent. More data are available for the liver, as a lipid rich tissue and the major site of xenobiotic catabolism, but the concentrations have rarely been related to its capacity to produce vitellogenin or metabolise endogenous hormones. Tissue concentrations of a wide range of chemicals, are at a level which suggests that, either alone or in combination, they will cause significant endocrine disruption in fish in many polluted habitats. 

ACTH = adrenocortico-trophic hormone T4 = thyroxine T3 = triiodothyronine E, = estradiol T = testosterone I7,20/IP = 17,20/1-dihydroxy-4-pregnen-3-one KT = Il-ketotestosterone VTG = vitellogenin. 

The liver plays an important role in the endocrine system. The concentrations of hormones in plasma, and the activity of the glands which secrete them, are determined by the rate at which they are deactivated by the liver. The liver also has a major function in female reproduction since it is the target tissue of ovarian estrogen, to which it responds by producing the yolk protein vitellogenin. " Xenobiotics that affect either of these functions can therefore be considered to be potential endocrine disrupters. 

There is some evidence for chemically mediated endocrine disruption in amphibians. The egg yolk protein, vitellogenin, is inducible in amphibians by exposure to DDT. " Males of the short clawed toad Xenopus laevis given 250 fig/g or 1 fig/g o,p -DDT for seven days have been shown to produce vitellogenin, although the induction was less than that achieved by treatment with 1 fig/g of either 17/1-oestradiol or diethylstilboestrol. Research has also shown that endocrine disrupting chemicals can alter sex ratios in wild populations of certain species PCB congeners and organochlorine compounds have been linked with male domination of sex ratios in polluted compared to unpolluted sites. ... 

Phytoestrogens Isoflavones genistein ER/1, ERa" 3 Agonist Induces vitellogenin expression,... 

Catfish (Clarias batrachus) plasma vitellogenin levels were significantly decreased after 48 hours of exposure to 0.0015 mg/L of commercial-grade endosulfan (Chakravorty et al. 1992). Levels did not recover substantially with injections of various hormones, including estradiol. In rainbow trout, endosulfan did not induce vitellogenin production at 9 days after a single intraperitoneal injection of 5 mg/kg in peanut oil (Andersen et al. 1999). 

Vitellogenin A protein that forms part of the yolk of egg-laying vertebrates. 

Folmar, L.C., Denslow, N.D., Rao, V. et al. (1996). Vitellogenin induction and reduced serum testosterone concentrations in feral male carp (Cyprinus carpio) captured near a major metropohtan sewage treatment plant. Environmental Health Perspectives 104, 1096-1101. 

Om, S., Holbech, H., and Madsen, T.H. et al. (2003). Gonad development and vitellogenin production in zebrafish (Danio rerio) exposed to ethinylestradiol and methyltestoster-one. Aquatic Toxicology 65, 397-411. 

Pelissero, C., Flouriot, G., and Foucher, J.L. (1993). Vitellogenin Synthesis in Cultured-Hepatocytes—an in vitro Test for the Estrogenic Potency of Chemicals. Journal of Steroid Biochemistry and Molecular Biology 44, 263-272. 

Thorpe, K.L., Hutchinson, T.H., and Hetheridge, M.J. et al. (2001). Assessing the biological potency of binary mixtures of environmental estrogens using vitellogenin induction in juvenile rainbow trout Oncorhynchus mykiss). Environmental Science and Technology 35, 2476-2481. 

Vermeirssen, E.L.M., Burki, R., and Joris, C. et al. (2005). Characterization of the estrogenic-ity of Swiss midland rivers using a recombinant yeast bioassay and plasma vitellogenin concentrations in feral male brown trout. Environmental Toxicology and Chemistry 24, 2226-2233. 

Andersen L, Holbech H, Gessbo A, Norrgren L, Petersen GI (2003) Effects of exposure to 17 alpha-ethinylestradiol during early development on sexual differentiation and induction of vitellogenin in zebrafish (Danio rerio). Comp Biochem Physiol C-Toxicol Pharmacol 134 365-374... 

F. Darain, D.S. Park, J.-S. Park, S.-C. Chang, and Y.-B. Shim, A separation-free amperometric immunosensor for vitellogenin based on screen-printed carbon arrays modified with a conductive polymer. 

Lattier D, Gordon D, Burks D, Toth G (2001) Vitellogenin gene transcription a relative quantitative exposure indicator of environmental estrogens. Environ Toxicol Chem 20 1979-1985... 

Garcia-Reyero N, Raldua D, Quiros L, Llaveria G, Cerda J, Barcelo D, Grimalt JO, Pina B (2004) Use of vitellogenin mRNA as a biomarker for endocrine disruption in feral and cultured fish. Anal Bioanal Chem 378 670-675... 

Egg production constitutes a major loss of zinc and other trace metals by the laying hen. Vitellogenin mediates the transfer of zinc from liver to the maturing oocyte, ultimately resulting in deposition into yolk of the newly formed egg (Richards 1989). More research seems needed on the role of zinc in avian reproduction. 

Olsson, P.E., M. Zafarullah, and L. Gedamu. 1989. A role of metallothionein in zinc regulation after oestradiol induction of vitellogenin synthesis in rainbow trout, Salmo gairdneri. Biochem. Jour. 257 555-559. 

Ruby, S.M., D.R. Idler, and Y.P. So. 1986. The effect of sublethal cyanide exposure on plasma vitellogenin levels in rainbow trout (Salmo gairdneri) during early vitellogenesis. Arch. Environ. Contam. Toxicol. 15 603-607. 

From these studies, some patterns of effect potentially mediated by the endocrine system have been observed. These include the accumulation of vitellogenin in ticks [50-52] and accelerated ovarian development in beetles and ticks [51, 53]. Different researchers have attributed these effects to a range of different mechanisms, including induced excitation of neurosecretory cells releasing juvenile hormone [50], and ecdysteroid disruption either by blocking the neuropeptide itself or at the epidermal site of synthesis [51]. Other researchers have not corroborated these results and have even found contradictory effects, e.g., suppressed ovarian development [52], Therefore at present for SPs, there is no clear evidence for adverse population-relevant effects with an underlying endocrine mode of action. 

---