Modification of nerve growth factor and sex steroid in development of hypothalamic neurons.

The medial basal hypothalamic (MBH) tissues were taken from rat fetuses at day 17-18 of gestation and transplanted into the third ventricle of adult female rats. 2.5 S mouse nerve growth factor (NGF) was infused into the third ventricle of some hosts for 2 weeks using a mini-osmotic pump. The other hosts were implanted silastic capsules containing estradiol. Three weeks after the operation, the transplants were immunocytochemically stained with anti-tyrosine hydroxylase (TH) antibody. A number of immunoreactive neurons was obtained in all of NGF-treated, estrogen-exposed and control transplants. Immunoreactive axons distributed densely in NGF-treated transplants. However, the distribution of immunoreactive axons was less dense in estrogen-exposed and control MBH transplants. These results suggest that NGF infused into the host ventricle stimulates the growth and/or regeneration of axons of hypothalamic neurons. In contrast, action of estrogen on transplanted hypothalamic tissues was not evident in the present study.