M.W. 
C 2 4 24 48 
Time (hours) After Injection 
FIGURE 1 0. Western blot analysis of Fos-immunoreactive proteins at 
different times following cocaine 30 mg/kg IP. The numbers 
at the left show the molecular weight markers (M. W. Stds in 
kDa); those on the right, the molecular weights for the Fos- 
immunoreactive proteins as recognized by the broadly specific 
anti-Fos antisera. The 55-kDa protein corresponds to the c-fos 
gene product; those below, to the various Fra’s. An increase in 
Fos protein is seen as early as 1 hour in further repetitions of 
this experiment; the Fra proteins lag behind the increase in Fos 
protein. 
SOURCE: Young et al. 1991 
inhibitor. Although this is interesting in itself, the main point of the anisomycin 
treatment was to determine whether it blocked or attenuated the increase in c- 
fos transcripts. We did not observe an attenuation, and this reinforces the idea 
that the increase in c -fos seen with cocaine is part of a broader spectrum of IEG 
activation in caudate-putamen and ventral striatal areas that involves not only 
fos but other lEGs as well (Hope et al. 1992). 
We have shown that an acute injection of cocaine induces c -fos mRNA, Fos 
protein, and several other Fos-immunoreactive proteins (Fra’s) and that these 
196 
