a Identified myelinated Ah-type BRNs. b Identified unmyelinated C-type BRNs. Averaged data were presented as mean ± SD, and n = 39 for OVI, 49 for OVX, and 27 for OVX + E2 in the category of Ah-types, n = 20 for OVI, OVX, and OVX + E2, respectively, in the category of C-types. The data points (n) from each group were collected from at least 6 rats. **P < 0.01 vs. OVI, ##P < 0.01 vs. OVX.