Effects of Nonylphenol on the Secretions of Catecholamines, Gonadotropin-Releasing Hormone (GnRH) and Kisspeptin from Short-Term Incubated Rat Hypothalamus.

Previously, we developed a short-term incubation method of rat adrenal and demonstrated that nonylphenol (NP) exposure could induce changes in secretions of adrenal hormones. In the present study, the effects of NP on changes in hormonal secretion from hypothalamus were investigated. The catecholamine levels were measured using high-performance liquid chromatography with electrochemical detection (HPLC-ECD) and the levels of gonadotropin-releasing hormone (GnRH) and kisspeptin were measured using enzyme-linked immunosorbent assay (ELISA). The norepinephrine (NE) levels from NP-treated male and female hypothalamus were not significantly changed across the entire treatment concentration (from 1 nM to 1 μM), except male 10 nM-treated group which were significantly lower than control (<0.05). The epinephrine (E) levels from NP-treated female hypothalamus were significantly increased in 100 pM- and 1 nM-trated group (<0.05). However, the E levels from NP-treated male hypothalamus were significantly decreased in 100 pM- and 10 nM-treated group (<0.05). The GnRH levels from NP-treated hypothalamus showed an increasing trend, especially significant in male 10 nM- and 100 nM-treated groups (<0.001) and female 1 nM-, 100 nM- and 1 μM-trated groups (<0.05, <0.01 and <0.05, respectively). Also, the kisspeptin levels in incubated media of both sexes showed a strong increasing trend, especially significant in male 1 nM- and 10 nM-treated groups (<0.05) and all of female groups except 10 nM-treated. In conclusion, our incubation method could be quite suitable for rapidly and effectively measuring endocrine disrupting chemicals (EDC) activity in hypothalamus. NP treatment shown stimulatory effects on both GnRH and kisspeptin secretions from hypothalamus of both sexes, suggesting possible relationship between NP exposure and reproductive phenomena and related disorders.