Aroclor 1254-induced alterations in hypothalamic monoamine metabolism in the Atlantic croaker (Micropogonias undulatas): correlation with pituitary gonadotropin release

Abstract

Male Atlantic croaker (Micropogonias undulatus) were exposed to Aroclor 1254 (a PCB mixture) in the diet (0.1 mg/100 g body wt./day) for 30 days during gonadal recrudescence to investigate the effects of the PCB mixture on reproductive neuroendocrine function. The concentrations of biogenic amines (epinephrine [E], norepinephrine [NE], dopamine [DA], and 5-HT) and their major metabolites (3,4-dihydroxyphenylacetic acid [DOPAC], 3-methoxytyramine [3-MT], homovanillic acid [HVA], and 5-hydroxyindolacetic acid [5-HIAA]) were measured in the preoptic-anterior hypothalamus (POAH) and medial and posterior hypothalamus (MPH) using HPLC with electrochemical detection. There was a significant decline in 5-HT and DA concentrations and an increase in their metabolite to parent amine ratios in both the POAH and MPH of Aroclor 1254-exposed fish. In addition, Aroclor 1254 exposure resulted in the loss of the in vitro pituitary gonadotropic response to stimulation by a luteinizing hormone-releasing hormone analog (LHRHa). We have previously shown that 5-HT modulates the gonadotropin release in response to LHRHa in Atlantic croaker. Therefore, the reduced availability of neuronal 5-HT may be at least partially responsible for the loss of the gonadotropic response to stimulation by LHRHa.