The Effects of a Highly Chlorinated Biphenyl—Delor 106—on the in Vivo and in Vitro Luteinizing Hormone Secretion in Female Prussian Carp, Carassius Gibelio (Actinopterygii: Cypriniformes: Cyprinidae)

Background. Endocrine disrupting chemicals (EDCs), among them polychlorinated biphenyls (PCBs), are able to change the hormonal regulation of reproduction at the hypothalamo-pituitary-gonadal (HPG) axis in many vertebrates. The aim of the presently reported study was to determine the effects of highly chlorinated PCBs mixture--Delor 106--on the in vivo and in vitro luteinizing hormone (LH) secretion from the pituitary gland of female Prussian carp, Carassius gibelio (Bloch, 1782), at the time of natural spawning. Materials and methods. In the in vivo experiment we tested exposure to Delor 106: acute (one week at the concentration of 700 ng times L super(-1)) and chronic (5 weeks at increasing weekly concentrations, from 140 through 700 ng times L super(-1)). Blood samples from all females were taken before intoxication (0 week) and subsequently every week (week 1 through 5) till the end of the experiment. In the in vitro experiment enzymatically dispersed pituitary cells obtained from sexually mature Prussian carp females were incubated for 5 or 24 h in the presence of Delor 106 at the concentrations of: 1, 5, 10, 50, or 100 ng times mL super(-1) of medium. LH levels in the incubation medium as well as in blood plasma were measured using ELISA method. Results. Long-term (3 and 4 weeks) exposure to the Delor 106, gradually added to the water, caused a significant elevation of spontaneous LH secretion. Pituitary cells incubation with Delor 106 at the concentration range from 10 through 100 ng times mL super(-1) of medium resulted in the significant increase of spontaneous LH secretion after 5 and 24 h. Conclusion. The results obtained in this study show that highly chlorinated biphenyl--Delor 106--changes the secretion of luteinizing hormone in Prussian carp in the spawning season, acting, at least in part, directly at the pituitary level.