Effect of hypophysectomy on immunocytochemically demonstrated growth hormone releasing factor (GHRF) in the rat brain.

The effect of removal of CH by long-term hypophysectomy (HPX) on the GHRF-immunoreactivity in the rat hypothalamus was studied using immunocytochemical methods. HPX resulted in a dramatic reduction in immunostaining in the median eminence (ME), indicating a significant reduction in storage of GHRF. Other regions of the hypothalamus, including the dorsomedial nucleus, the medial preoptic and suprachiasmatic regions, and the lateral hypothalamus showed the distribution and intensity of GHRF-immunoreactive structures as seen in intact animals; i.e., scattered fibers only. A few weakly stained cell bodies were seen in experimental and control animals. This could be due to a lack of storage, and/or this peptide may possibly not be present in its matured and fully immunoreactive form in the cell bodies.