80 -- 
co 
z 
o 
a: 
3 
3 
a: 
0 
z 
3 
2 
3 
1 
CO 
o 
60 
40 -■ 
20 -- 
SAL 0.006 0.02 0.06 0.20 0.60 
DOSE OF ICV DAMGO Oxg) 
FIGURE 1 0. Effects of ICV DAMGO on noxious stimulus-evoked FLI in the 
spinal cord. Animals (n=3 per dose) were treated and the tissue 
processed as described in the text. Results are expressed as 
mean (±SEM) number of neurons per 50-pim section expressing 
FLI in either the superficial (•), nucleus proprius (m), neck (A), 
or ventral (A) portions of the ipsilateral spinal cord. Drug 
treatments are indicated on the abscissa. The potency for 
CV DAMGO-mediated inhibition of FLI in the superficial region 
(ED so =0. 18 pig) was approximately four times less than for 
either the neck or ventral regions (ED so =0.04 and 0.05 pig, 
respectively). The curve for inhibition of the nucleus proprius 
was flatter than for the other regions of the cord, with significant 
inhibition only at 0.60 pig ICV DAMGO. Note that the highest 
dose of ICV DAMGO tested (0.60 pig) produced 100-percent 
inhibition of pain-related behaviors without producing 
comparable levels of inhibition in FLI at the level of the cord. 
SOURCE: Reprinted with permission from Neuroscience 42, Gogas, K.R.; 
Presley, R.W.; Levine, J.D.; and Basbaum, A.I. The antinociceptive 
action of supraspinal opioids results from an increase in 
descending, inhibitory control: Correlation of nociceptive behavior 
and c-fos expression, 1991, Pergamon Press, pic. 
152 
