Figure 2.

Effects of a ventral cut of the LS (VC) on lordotic activity and neural projection from the LS to MCG in male rats. (A) Estradiol-17β (E₂)-treated castrated male rats with or without VC were tested for lordosis behavior and then injected with Fluoro-Gold (FG), a retrograde neurotracer, into the MCG. FG-labeled neurons in the LS were detected by immunohistochemistry. (B) The mean LQ of E₂-treated castrated male rats with VC (VC male) was increased over time (days) after E₂ treatment, like an E₂-treated ovariectomized female (control female), but the mean LQ of E₂-treated castrated male rats without VC (control male) was low. (C) Photomicrographs of the LS of control and VC male rats that received FG injection into the MCG on the right side. Many FG-labeled neurons were found in the LSi of control male rats, but not in the LSi of VC male rats. Arrowheads indicate the scar of VC. Scale bars = 500 μm. gcc, genu of the corpus callosum; LS, lateral septum; LSi, intermediate part of the LS; LV, lateral ventricle; MCG, midbrain central gray. (D) The number of FG-labeled neurons in the LSi of control male rats was significantly greater than that of VC male rats on the ipsilateral and contralateral side of the FG injection site. The LSi of control male rats contained many more FG-labeled neurons on the ipsilateral side of the FG injection site. ^††p < 0.01 vs. control male rat; ^*p < 0.05 vs. contralateral side (modified from Tsukahara and Yamanouchi, 2001).