Are neurons of the arcuate nucleus necessary for pathfinding by GnRH fibers arising from third ventricular grafts?
The hypogonadal (hpg) mouse lacks GnRH due to a severe truncation of the gene by which it is encoded. This results in an infertile animal with an infantile reproductive system. When fetal or 1-day postnatal septal/preoptic area of a normal mouse is grafted into the third ventricle of an hpg mouse, GnRH-containing fibers grow out of the grafts and innervate the host median eminence (ME), a normal target of these fibers. GnRH axons exiting the graft course follow a very stereotyped pathway through host tissue. They are observed passing through the ependymal wall of the ventricle directly into the ME or arching through the host arcuate nucleus to terminate in the host ME. Given the fixed pattern of outgrowth, we wanted to determine if the neurons of the arcuate nucleus, which lie between the graft and its target, are exerting an influence on the growth and direction of these fibers. The excitotoxin monosodium glutamate (MSG) has been shown to destroy the vast majority of arcuate neurons w
