Effect of pulse exposure to methoxychlor on brain serotonin levels in american flagfish (Jordanella Floridae, goode and bean) as modified by time after exposure, concentration and gender

Abstract

AbstractAdult American flagfish (Jordanella floridae) were exposed for 2 h to 1.6, 1.9, 3.1 or 5.1 mg L−1 of the chlorinated hydrocarbon insecticide methoxychlor. Control and ethanol‐carrier control treatments were also maintained. Fish were sampled at 2, 6, 24, 48 and 336 h after exposure, and the concentrations of tryptophan, serotonin and 5‐hydroxyindole acetic acid in brain tissue were determined. Flagfish exposed to the three highest concentrations of methoxychlor had significantly lower concentrations of serotonin, relative to controls, 2, 6 and 24 h after exposure. Serotonin concentrations had returned to control levels by 48 h. The period of serotonin depression corresponded with observed convulsive activity in the exposed fish. Female flagfish had significantly higher brain levels of serotonin than did males. Although tryptophan and 5‐hydroxyindole acetic acid levels were unaffected by methoxychlor exposure, the levels of both were significantly depressed by the concentration of ethanol carrier (270 mg L−1) used. Serotonin levels were unaffected by ethanol. The brain weight of flagfish was found to be related to body weight by the equation brain weight (mg) = 2.53 + 5.72 body weight (g) (n = 139; r2 = 0.74; p < 0.001).