Somatostatin binding sites in the white matter of the developing human brainstem: inverse relationship with the myelination process

The ontogeny of somatostatin binding sites was studied in eight fiber tract s of the human lower brainstem in 18 fetuses and infants aged from 21 weeks postconceptional to 6 months postnatal, and in two adults. The study was p erformed by means of quantitative autoradiography using [I-125-Tyr(0),DTrp( 8)]somatostatin-14 as a radioligand. For all structures examined, the highe st densities of binding sites were detected in the younger stages and the d ensity of sites decreased during development. These results reveal the exis tence of a close inverse relationship between the density of somatostatin r eceptors and the myelination process in the fiber tracts of the human brain stem. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.