OPIATE WITHDRAWAL INCREASES PROTRH GENE-EXPRESSION IN THE VENTROLATERAL COLUMN OF THE MIDBRAIN PERIAQUEDUCTAL GRAY

The midbrain periaqueductal gray matter (PAC) has a critical role in t he modulation of behavioral and autonomic manifestations of the opiate withdrawal syndrome. We report a nearly 5-fold increase in proTRH gen e expression in neurons of the ventrolateral column of the FAG followi ng naltrexone precipitated morphine withdrawal. The accumulation of im munoreactive proTRH-derived peptides, but not the mature TRH tripeptid e was concomitantly observed in these cells. These findings indicate t hat proTRH-derived peptides synthesized in neurons of the ventrolatera l FAG may function as modifiers of opiate withdrawal responses.