Ultrastructural demonstration of nerve endings containing a substance related to growth hormone-releasing factor in the guinea-pig paraventricular nucleus.

By means of a preembedding immuno-electron-microscopic technique, a large number of nerve endings containing a substance related to human growth hormone-releasing factor (hGRF) have been demonstrated in the paraventricular nucleus of the guinea pig. They made synaptic contacts primarily with dendritic shafts: 80% of these contacts were symmetrical. The immunoprecipitate was located mainly in large granules and around small clear vesicles. These findings suggest that a peptide related to hGRF may play a role in neural communication in the paraventricular nucleus.