The effect of hypothalamic deafferentation on rat growth hormone-releasing factor (rGRF)-like immunoreactivity content in the medial basal hypothalamus of rats.

Rat growth hormone releasing factor (rGRF)-and somatostatin (SRIF)-like immunoreactivities (LI) were determined by radioimmunoassay in the medial basal hypothalamus (MBH) of the rat with either complete deafferentation (CD) or a sham operation. Two weeks after the surgery the mean amount of SRIF-LI in the isolated MBH was about 70% less than that in the shamoperated animals. On the other hand, the mean rGRF-LI in the MBH decreased only approximately 30% as compared to the levels in the sham-operated animals, the difference being statistically insignificant. These findings are consistent with anatomical evidence that the majority of the GRF perikarya are located in the arcuate nucleus, but a few are found outside the MBH, whereas the majority of the SRIF perikarya are located outside the MBH.