Figure 3.

A, Correlation between ACh levels and spontaneous locomotor activity in 2 gonadally intact and 2 ORX male rats. B, Simple linear regression analysis showed that the data from intact males (#100 and #102) had a steep slope of the fit line, whereas the data from ORX males (#88 and #107) had a gentle slope. C, Orchidectomy reduced both correlation and slope, with testosterone replacement (+T) restoring the property in male groups. D, OVX reduced the correlation, with steroid replacement either testosterone or 17β-estradiol (+E) restoring the property in female groups. *p < 0.01 compared with males (both correlation and slope). ^#p < 0.01 compared with cycling females (correlation only). Moreover, intact males had significantly steeper slope than cycling females (p < 0.01). Data in C and D represent the means ± SEM.