Modulation of brain serotonin by benzyl butyl phthalate in Fundulus heteroclitus (mummichog)

Endocrine-disrupting chemicals have been known to alter important animal behaviors by modulating serotonin (5-hydroxytryptamine, 5-HT) and dopamine. F. heteroclitus (mummichog) brain serotonin and dopamine levels were quantified by enzyme-linked immunosorbent assay (ELISA) following a 28-day exposure regimen involving daily doses of either 0.1 mg l^-1 benzyl butyl phthalate (BBP) dissolved in acetone or acetone alone (0.1 mg l^-1). No differences in mean brain mass or total protein homogenate were induced by exposure to the acetone vehicle or BBP in acetone. The acetone vehicle had no effect on dopamine, serotonin, or tyrosine hydroxylase levels, but acetone did decrease tryptophan hydroxylase levels (p = 0.011). Exposure to BBP in acetone decreased dopamine (p = 0.024), increased serotonin (p < 0.001), reduced tryptophan hydroxylase as compared to the acetone vehicle alone (p < 0.001), and had no significant effect on tyrosine hydroxylase levels. This study is the first to report modulation of F. heteroclitus brain serotonin and its enzyme tryptophan hydroxylase following sub-lethal exposure to BBP in an acetone vehicle. In addition, modulation of brain dopamine in F. heteroclitus, sans simultaneous modulation of tyrosine hydroxylase, was also observed. These findings support the use of F. heteroclitus for assessing sub-lethal BBP exposure.