Bisphenol A inhibits compound action potentials in the frog sciatic nerve in a manner independent of estrogen receptors

Abstract

Although the endocrine disruptor bisphenol A (BPA) is reported to inhibit nerve conduction, the underlying mechanisms are unclear. Therefore, in the present study, we examined the effect of BPA on compound action potentials (CAPs) recorded from the frog sciatic nerve using the air-gap method. Treatment of the sciatic nerve with BPA (0.5 mM) for 20 min reduced the peak amplitude of the CAP by approximately 60% in a partially reversible manner. The reduction in the CAP peak amplitude was concentration-dependent, with a half-maximal inhibitory concentration (IC50) value of 0.31 mM. This effect of BPA was unaffected by an estrogen-receptor antagonist, 4-hydroxytamoxifen, which by itself reduced CAP peak amplitude, with an IC50 value of 0.26 mM (comparable to that of BPA). The natural estrogen 17β-estradiol, at the highest dissolvable concentration (0.05 mM), had an effect similar to that of BPA. The IC50 value of BPA was comparable to those of some local anesthetics in inhibiting frog CAPs. Our findings suggest that BPA inhibits nerve conduction in a manner independent of estrogen receptors. This action of BPA may underlie, at least in part, the neurotoxicity of the compound.

Keywords

• Bisphenol A
• 17β-Estradiol
• Local anesthetic
• Nerve conduction inhibition
• Sciatic nerve
• Frog