The spinal motonucleus of genitofemoral nerve regulating scrotal temperature also can be related to prenatal and neonatal testicular descent by gubernacular change in rats, and sexually dimorphic like bulbocavernosus/dorsolateral motonucleus.
There
is a
hypothesis that neonatal androgen affects these motonuclei, and induce development of sexual organ throgh neural stimulation. Until now, the accumulation of isotope labelled androgen and immunoreactivity of androben receptor protein in each
sexually
dimorphic spinal motonucleus have been revealed in adult rats but not been established in rats of neonatal periods. To investigate the presence of the androgen receptor in spinal sexually dimorphic motonuclei in neonatal period, we evaluated the
androgen receptor immunoreactivity of these motonuclei. In Sprague-Dawley male rats, the lumbar spinal cords were resected according to cord level by laminectomy under dissecting microscope after parformaldehyde perfusion fixation at postnatal
day
3
(n=6), 10 (n=7) and 30 (n=6). The resected spinal cords were serially sectioned 50 ㎛ thick by vibratome, and stained immunohistochemically using polyclonal antibody of androgen receptor protein. The immunoreactivity of androgen receptor protein
was
observed in the cells of genitofemoral motonucleus from the thirteenth thoracic to the second lumbar spinal cord and bulbocavernosus/dorsolateral from the thirteenth thoracic to the second lumbar spinal cord and bulbocavernosus/dorssolateral
motonucleus
was observed from the 5th to 5 th lumbar spinal cord and bulbocavernosus/dorsolateral motonucleus was observed from the 4 th to 5 th lumbar spinal cord at all age groups. The proportional areas of both motonuclei of day 3 and 10 on cross section
were
larger than that of day 30. The motonuclei of day 3 and 10 were more laterally located, compared to that of day 30. The immunostaining densities were sim8ilar in all age groups. With the above results, the presence of androgen receptor protein
was
confimrmed in the genitofemoral and bulbocavernosus/dorsolateral motonucleus from neonate to day 30. The larger proportional area of these motonuclei in uenoates may indicate active role of these motonuclei during neonatal period. Although the
immunoreactivity does not directly imply the presence of funtional receptor, neonatal androgen could be reponsible for the development of sexual organ through the spinal motonucleus.
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