Sex Dependent Action of Aroclor 1254 on Basal and sGnRHa-Stimulated Secretion of LH from the Pituitary Cells of Common Carp, Cyprinus carpio L.

Abstract

Polychlorinated biphenyls (PCBs) affect the hypothalamic-pituitary-gonadal axis in many vertebrates, changing the hormonal regulation of reproduction. To identify one of the possible sites of action of PCBs on gonadotropin release in common carp, the direct effects of Aroclor 1254 on luteinizing hormone (LH) secretion from dispersed pituitary cells were investigated. Pituitary cells were obtained from sexually mature male and female common carp (Cyprinus carpio L.) at the time of natural spawning. The cells were incubated with different concentrations of Aroclor 1254 (5, 10, 50 and 100 ng mL−1 medium) and/or salmon gonadotropin-releasing hormone analogue (sGnRHa) at a concentration of 10−8 M. LH levels were measured in the cultured medium by the ELISA method after 10 hours of cell incubation. Incubation of male pituitary cells in the presence of tested concentrations of Aroclor did not change the basal LH secretion to the media. In the female pituitary cell incubations Aroclor (5, 10 and 100 ng mL−1 medium) caused a significant increase in LH concentrations in comparison to control incubations. In the case of sGnRHa-stimulated LH secretion in incubations of cells of both sexes, all the concentrations of Aroclor significantly stimulated LH release and potentiated stimulatory effects of sGnRH analogue. These results indicate that endocrine disrupters, such as Aroclor 1254, may affect reproduction in fish, acting also directly on gonadotrophs at the level of the pituitary gland, changing LH secretion.