ACUTE OPIATE ACTION IN THE LC 
plaama 
membrane' 
(v I P-r) (opiate receptor) 
w w V)~(.s 
"jadenylate 
l cyclase 
cyclic^ AMP 
cyclic AMP-dependent 
protein kinase 
dephospho- 
protelns 
protein phosphatase 
phospho- 
proteins 
CHRONIC OPIATE ACTION IN THE LC 
plaama 
(vip-r) (opiate receptor) 
(Gs) (Gi>fr (Go 
Ion 
j channela 
adenylate 
cyclase 
cyclic AMP 
I 
cyclic AMP-dependent 
protein kinase 
dephospho- 
proteins 
phospho- 
proteins 
protein phosphatase 
Many other changes 
in neuronal function 
Maintenance of new steady- 
state of gene expression 
FIGURE 1 . Schematic illustration of the mechanisms of acute and chronic 
opiate action in the LC. See text for discussion. 
VIP-R=vasoactive intestinal polypeptide receptor 
SOURCE: Modified from Nestler 1992. Copyright 1992 by Society for 
Neuroscience (New York). 
98 
