Modulation of monoamine neurotransmitters in fighting fish Betta splendens exposed to waterborne phytoestrogens

Abstract

Endogenous estrogens are known to affect the activity of monoamine neurotransmitters in vertebrate animals, but the effects of exogenous estrogens on neurotransmitters are relatively poorly understood. We exposed sexually mature male fighting fish Betta splendens to environmentally relevant and pharmacological doses of three phytoestrogens that are potential endocrine disruptors in wild fish populations: genistein, equol, and β-sitosterol. We also exposed fish to two doses of the endogenous estrogen 17β-estradiol, which we selected as a positive control because phytoestrogens are putative estrogen mimics. Our results were variable, but the effects were generally modest. Genistein increased dopamine levels in the forebrains of B. splendens at both environmentally relevant and pharmacological doses. The environmentally relevant dose of equol increased dopamine levels in B. splendens forebrains, and the pharmacological dose decreased norepinephrine (forebrain), dopamine (hindbrain), and serotonin (forebrain) levels. The environmentally relevant dose of β-sitosterol decreased norepinephrine and dopamine in the forebrain and hindbrain, respectively. Our results suggest that sources of environmental phytoestrogens, such as runoff or effluent from agricultural fields, wood pulp mills, and sewage treatment plants, have the potential to modulate neurotransmitter activity in free-living fishes in a way that could interfere with normal behavioral processes.

Social status differences regulate the serotonergic system of a cichlid fish, Astatotilapia burtoni

“…4). Levels of 5-HT and 5-HIAA were comparable to those in other studies for fish of comparable size to A. burtoni (Clotfelter et al, 2010;Larson et al, 2003) and did not differ between social groups in any of the brain regions ; all MWU) (supplementary material Fig. S2).…”

Social Opportunity Rapidly Regulates Expression of CRF and CRF Receptors in the Brain during Social Ascent of a Teleost Fish, Astatotilapia burtoni

“…Serotonin is well known for its role in modulating social behavior, aggression and sex change in teleost fishes [76], [77]. In addition, serotonin levels are sensitive to CRF activity, and seem to play a role in modulating anxiety-like behavior in fish [21].…”

Determination of seventeen endocrine disruptor compounds and their spatial and seasonal distribution in Ria Formosa Lagoon (Portugal)

“…This observation is quite worrying since when SITO concentrations surpass 10,000 ng L −1 it can act as an endocrine disrupter for aquatic animals (Clotfelter et al 2010). …”

“…Despite the high water turnover at each tide, several studies reported eutrophication and hypoxia, mainly in summer at some spots of the lagoon (Newton and Mudge 2005;Newton et al 2010); however, no information exists about the presence of either phytoestrogens or the annual fluctuation patterns of sitosterol. These compounds in spite of being of natural/vegetal sources, in high amounts phytoestrogens and sitosterol, are known to act as endocrine disrupter compounds (EDCs; Hoerger et al 2009;Clotfelter et al 2010). Thus, beyond the last compounds, the present study aimed to provide the first data for the Ria Formosa Lagoon about the levels of several of the most concerning worldwide anthropogenic/industrial EDCs such as estradiol, estrone, ethynylestradiol, 4-n-octylphenol, 4-toctylphenol, nonylphenol, several polyethoxylates (4-octylphenol monoethoxylate, 4-octylphenol diethoxylate, 4-nonylphenol monoethoxylate, 4-nonylphenol diethoxylate), and bisphenol A.…”