PRE-PRO-SOMATOSTATIN MESSENGER-RNA IN THE DEVELOPING RAT SPINAL-CORD WITH SPECIAL REFERENCE TO VENTRAL HORN MOTONEURONS

The expression of pre-pro-somatostatin (ppSOM) mRNA in the spinal cord of the developing rat was determined by in situ hybridization. Expres sion of ppSOM mRNA was detected in cells in the gray matter of the dor sal and ventral horns at day E15, the earliest stage examined in this study. Expression of ppSOM mRNA persisted during development and into adulthood in the dorsal horn. In contrast, ppSOM mRNA expression in pr esumptive ventral horn motoneurons was apparent during pre- and perina tal periods, but it was not observed in adult rats. These findings are consistent with the hypothesis that ppSOM is transiently expressed by motoneurons and that a peptide derived from it may serve a role in th e development of the neuromuscular junction.