LOCAL OPIATE WITHDRAWAL IN LOCUS-COERULEUS IN-VIVO

Hyperactivity of noradrenergic locus coeruleus (LC) neurons following withdrawal from chronic opiates has been implicated in the opiate with drawal syndrome. Here, we report that local withdrawal induced in vivo by microinfusion of an opiate antagonist into the LC of morphine-depe ndent rats marginally, but significantly, activated LC neurons above t he level obtained with local naloxone microinfusion in naive rats. Thi s local withdrawal response contributes a significant fraction (simila r to 19%) of the total LC hyperactivity induced by systemic naloxone. (C) 1997 Elsevier Science B.V.