EVIDENCE FOR LOCALIZATION OF THE TRANSGENE PRODUCT WITHIN AXON TERMINALS IN THE DENTATE GYRUS OF TRANSGENIC MICE EXPRESSING HUMAN PHENYLETHANOLAMINE N-METHYLTRANSFERASE - A LIGHT AND ELECTRON-MICROSCOPIC IMMUNOCYTOCHEMICAL STUDY

The aim of this study was to examine whether protein products of a tra nsgene are localized within axon terminals in transgenic mice. We have previously created transgenic mice containing a chimeric gene compose d of the human dopamine beta-hydroxylase gene promoter and the human p henylethanolamine N-methyltransferase (PNMT) cDNA. In the present stud y, we used an antiserum that detects specifically human PNMT but not m ouse PNMT, and examined immunocytochemically the hippocampal formation of the transgenic mice. At a light microscopic level, immunoreactivit y of human PNMT was found in fiber plexuses in the outer molecular lay er of the dentate gyrus, and in cell bodies of layer 2 of the entorhin al cortex. At an electron microscopic level, in the outer molecular la yer of the dentate gyrus, human PNMT immunoreactivity was observed in axon terminals that formed synapses with dendritic spines. The present study provides the evidence for localization of the transgene's prote in products in axon terminals, suggesting axonal transport of the prod ucts.