100 - 
C0 
c 
o 
k. 
3 
a> 
o 
> 
o 
<3 
<X> 
k. 
o 
c 
3 
E 
E 
(jn 
o 
LL 
Dose of Morphine (mg/kg) 
FIGURE 7. Dose of morphine vs. the number of Fos-immunoreactive neurons 
in different laminar regions of the spinal gray matter (mean± 
SEM), including the superficial dorsal horn (laminae I and II), 
the nucleus proprius (laminae III and IV), the neck of the dorsal 
horn (laminae V and VI), and the ventral gray (laminae VII, VIII, 
and X). There was a statistically significant suppression of Fos- 
immunoreactive neurons after doses of morphine 2.5-10 mg/kg 
(*p<0.05, **p<0.01) in the superficial dorsal horn, in the neck of 
the dorsal horn, and in the ventral gray. The superficial dorsal 
horn consistently contained the greatest number of residual 
labeled cells; this was particularly evident at higher doses of 
morphine (5.0 and 10.0 mg/kg). In contrast, labeling in the ventral 
gray was eliminated by these doses. The dose-response curve 
for the nucleus proprius was flat, with no statistically significant 
suppression of labeling. 
SOURCE: Presley et al. 1 990. Copyright 1 990 by the Society for 
Neuroscience (New York). 
146 
