Fig. 1.

Lack of effect of 17β-estradiol (E₂) on the excitability of identified myelinated A-type and unmyelinated C-type vagal afferent neurons (VGN) from adult ovariectomized (OVX) rats. A and B: representative action potential (AP) recordings from VGN classified as myelinated A type and unmyelinated C type, respectively (see materials and methods). C: for myelinated A-type VGN, repetitive discharge elicited by 100- and 150-pA step currents. E: application of 1 μM E₂ failed to significantly alter discharge frequency at the same current magnitudes. D: for unmyelinated C-type VGN, 100- and 300-pA step current depolarizations elicited subthreshold and threshold response of a single AP, respectively. F: application of 1 μM E₂ failed to significantly alter the subthreshold and threshold discharge at the same current magnitudes.