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.