Hormone sensitivity of muscle activation in the sexually dimorphic SNB/BC neuromuscular system of the rat.
Rat penile reflexes are mediated in part by motoneurons in the sexually dimorphic spinal nucleus of the bulbocavernosus (SNB) and a muscle it innervates, the bulbocavernosus (BC). Recruitment in the M-wave component of electromyographic recording in the SNB/BC neuromuscular circuit is sensitive to testosterone and estradiol. To localize the site of the hormonal effect, we recorded muscle activity in a reduced preparation that isolated the peripheral structures involved in generating an M-wave. Castration reduced recruitment amplitude and increased response latency, and treatment with estradiol or the non-aromatizable androgen dihydrotestosterone prevented these changes. Dihydrotestosterone, but not estradiol, maintained BC muscle mass. These results indicate that functional changes in the SNB/BC circuit can result in part from hormonal sensitivity in the neuromuscular periphery and are independent of muscle mass.
Foster
Allison M
AM
Program in Neural Science, Department of Psychology, Indiana University, Bloomington, IN 47405, USA.
Sengelaub
Dale R
DR
D000818:Animals; D004576:Electromyography; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology*; D009919:Orchiectomy / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics
D012739:Gonadal Steroid Hormones