Immunoreactivity of androgen receptor protein in sexually dimorphic spinal motonucleus in neonatal male rats

The spinal motonucleus of the genitofemoral nerve regulating scrotal temperature can also be related to prenatal and neonatal testicular descent by gubernacular change in rats, and a sexually dimorphic-like bulbocavernosus/dorsolateral motonucleus. There is a hypothesis that neonatal androgen affects these motonuclei, and induces development of sexual organs through neural stimulation. Until now, the accumulation of isotope-labelled androgen and the immuno-reactivity of androgen receptor protein in each sexually-dimorphic spinal motonucleus have been revealed in adult rats but they have not been established in rats during neonatal periods. To investigate the presence of the androgen receptor in spinal sexually-dimorphic motonuclei in the neonatal period, we evaluated the androgen receptor immunoreactivity of these motonuclei. In Sprague-Dawley male rats, the lumbar spinal cords were resected at postnatal days 3, 10 and 30, and stained immunohistochemically using polyclonal antibody of androgen receptor protein. The immunoreactivity of androgen receptor protein was observed in the cells of the genitofemoral motonucleus from the 13th thoracic to the 2nd lumbar spinal cord and the bulbocavernosus/dorsolateral motonucleus was observed from the 4th to 5th lumbar spinal cord in all age groups. The proportional areas of both motonuclei at days 3 and 10 on cross-section were larger than at day 30. The motonuclei at days 3 and 10 were similar in all age groups. With the above results, the presence of androgen receptor protein was confirmed in the genitofemoral and bulbocavernosus/dorsolateral motonucleus from neonate to day 30. The larger proportional area of these motonuclei in neonates may indicate an active role for these motonuclei during the neonatal period. Although the immunoreactivity does not directly imply the presence of a functional receptor, neonatal androgen could be responsible for the development of sexual organs through the spinal motonucleus.

Immunoreactivity of Androgen Receptor Protein in Sexually Dimorphic Spinal Motonucleus in Neonatal Male Rats / 대한비뇨기과학회지

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 through neural stimulation. Until now, the accumulation of isotope labeled androgen and immunoreactivity of androgen 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 perform aldehyde perfusion fixation at postnatal day3 (n=6), 10 (n=7) and 30 (n =6). The resected spinal cords were serially sectioned 50 um 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 motonucleus was observed from the 4th to 5th 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 similar in all age groups. With the above results, the presence of androgen receptor protein was confirmed in the genitofemoral and bulbocavernosus/ dorsolateral motonucleus from neonate to day 30. The larger proportional area of these motonuclei in neonates may indicate active role of these motonuclei during neonatal period. Although the immunoreactivity does not directly imply the presence of functional receptor, neonatal androgen could be responsible for the development of sexual organ through the spinal motonucleus.

Effects of Neurotrophic Factor on Fetal Mesencephalic Grafts in Parkinsonian Rat Models

We investigated the usage of basic fibroblast growth factor administration to promote the survival of the dopaminergic neurons and behavioral efficacy of fetal mesencephalic grafts in rat parkinsonian models induced by 6-hydroxydopamine. The authors made partial lesioned rat parkinsonian models in which there was destruction of the dopaminergic nigrostriatal pathway & sparing of the mesolimbic pathway. A basic firoblastic growth factor was given continuously by using osmotic minipump into the lateral ventricle of the rat parkinsonian model for 2 weeks. Twelve weeks after grafts, all of the fetal mesencephalic grafts with basic fibroblast growth factor showed enhancement of the survival of dopaminergic neurons as well as activity of tyrosine hydroxylase in the caudate-putamen. Also, they accelerated the recovery in the grafted animals in test of apomorphine-induced rotational behavior when compare with that of the fetal mesencephalic grafts alone. The levels of tyrosine hydroxylase activity in the caudate-putamen were significantly enhanced in the fetal mesencephalic grafts with basic fibroblast growth factor and basic fibroblast growth factor alone compared with the control group. Those rats with fetal mesencephalic grafts with/without basic fibroblast growth factor or basic fibroblast growth factor alone showed the recovery in tests of apomorphine-induced rotational behaviors. Our study suggests that the basic fibroblast growth factor may be a neurotrophic factor for dopaminergic neurons, or may act indirectly by inducing the release of a dopaminergic trophic factor from other sources.