Morphological study of the spinal motoneurons controlling the urethral sphincter of female rats: Role of androgens in a menopausal model

Purpose: In this study in a menopausal rat model we describe the effect of androgen withdrawal on motoneurons innervating 2 muscles involved in female urinary continence, namely the intrinsic urethral sphincter and the pubococcygeus muscle. Materials and Methods: The 5 groups studied were 2 ovariectomized groups and their sham operated controls plus 1 ovariectomized group with dibydrotestosterone supplementation. Blood testosterone assays were performed. Androgen receptor immunohistochemistry was performed on spinal cord sections, in which specific motoneuron subpopulations were identified. Maximal somal cross-sectional area was compared among the groups. Results: Differences in somal cross-sectional area of motoneurons innervating the pubococcygeus muscle were observed after ovariectomy. Androgen receptor immunopositive nuclei staining disappeared, in line with undetectable blood testosterone levels. Discussion: The modifications of androgen receptor expression and somal morphological appearance in the pudendal motoneurons controlling the external urethral sphincter of ovariectomized female rats suggests that testosterone probably influences neurotransmission and coordination of urinary continence at the spinal level.