Effects of nonylphenol on Ca2+ mobilization in bovine adrenal chromaffin cells

• Main Author: 劉清輝
• Other Authors: 劉佩珊
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/47269332831113996307

碩士 === 東吳大學 === 微生物學系 === 90 === In addition to exerting genomic effects via intracellular steroid receptors, estrogen exerts nongenomic effects through interactions with membrane ion channels to lead the rapid alteration of neuronal excitability. Estradiol is known as to address the modulation the activities of membrane proteins, including nicotinic acetylcholine receptors (nAChR). Nonylphenol (NP), a common contaminant found in plastics and organic solvents, exerts genomic estrogenic-like effects via estrogen receptors. We investigated the possibility of NP exerting nongenomic estrogenic-like effects on calcium mobilization in bovine adrenal chromaffin cells. Our results show that NP inhibited Ca2+ signaling induced by high K+ solution (IC50 2.2 μM) as well as by the nicotinic ligand l, 1,1-dimethyl-4-phenyl- piperazinium iodide (DMPP) (IC50 0.9 μM). We therefore suggest that both nAChR and voltage-gated Ca2+ channels are addressing sites of NP on the plasma membrane. Its inhibitory effect on nAChR was found to be both noncompetitive and reversible, remaining unchanged as nAChR ligand concentration increased and decreasing after washing. In addition the above effects, NP itself can induce a calcium transient in the presence or absence of external calcium. Thapsigargin treatment will decrease the calcium transient induced by NP; this illustrates that NP release calcium from endoplasmic reticulum. We conclude that NP can interfere calcium mobilization, including it releasing internal calcium and inhibiting the calcium responses coupled with nAChR and voltage-gated ion channels.