Morphological Effects of Estradiol on the Neurons of the Major Pelvic Ganglia and the Urinary Bladders of Female Rats

To elucidate the effect of estradiol (E2) on the morphology of the neurons of the lower urinary tract during puberty, we carried out morphometric and immunohistochemical analyses of the major pelvic ganglia (MPG) in female rats. Four-week-old female Wistar rats were divided into the following groups: normal controls, ovariectomies, and ovariectomies receiving E2 replacement. At the age of 12 weeks the MPG were stained with hematoxylin and eosin (H&E), and immunostained by the antibody against rat tyrosine hydroxylase (TH). Each section was evaluated by an image analysis system. In the ovariectomized rats, the size of neurons in the MPG was significantly reduced. Immunohistochemical analysis revealed that the size of TH-positive neurons was significantly increased compared with TH-negative neurons in the E2-replaced rats. The results suggest that pubertal estrogen deficit reduces the size of neurons in the MPG and that estrogen replacement increases neuron size, especially the adrenergic neurons in the MPG.