SOMATOSTATIN, GALANIN AND PEPTIDE HISTIDINE ISOLEUCINE IN THE NEWBORNAND ADULT HUMAN TRIGEMINAL GANGLION AND SPINAL NUCLEUS - IMMUNOHISTOCHEMISTRY, NEURONAL MORPHOMETRY AND COLOCALIZATION WITH SUBSTANCE-P

By means of indirect immunofluorescence the neuropeptides somatostatin , galanin and peptide histidine isoleucine were localized in cell bodi es, nerve fibres and terminal-like elements in the ganglion and spinal nucleus of the human trigeminal nerve in perinatal and adult ages. No immunoreactivity to vasoactive intestinal polypeptide was observed. I n the gasserian ganglion somatostatin-, galanin- and peptide histidine isoleucine-containing neurons and nerve fibres occurred frequently in pre- and full-term newborns, but were scarce to absent in adults. Som atostatin- and galanin-positive pericellular basket-like structures ar ound nonimmunoreactive perikarya were observed in newborn specimens. I mmunoreactivity to somatostatin, galanin and peptide histidine isoleuc ine labelled nerve fibers and punctate and felt-like nerve terminals i n the pars interpolaris and subnucleus caudalis of the spinal trigemin al nucleus, with immunostaining and distribution patterns characterist ic for each peptide. In addition, somatostatin-containing neuronal cel l bodies frequently were detected. At variance with those containing s omatostatin, the number of galanin- and peptide histidine isoleucine-l ike immunoreactive elements were dramatically reduced in the adult tis sue compared to the newborn one. Double immunostaining revealed that e ach of the three peptides partially colocalizes with substance P, the degree of coexistence being very low for somatostatin/substance P and high for galanin/substance P and peptide histidine isoleucine/substanc e P both in the gasserian ganglion and in the spinal nucleus. The resu lts obtained suggest that somatostatin, galanin and peptide histidine isoleucine may play functional roles in primary sensory neurons and at the first synaptic level of the human trigeminal sensory system.