strategies were identical to those described above for LHRH and c-Fos. 
Approximately half the dopamine neurons within the arcuate nucleus of diestrus 
rats expressed FRA immunoreactivity (figure 8, panel A). In contrast, FRA 
immunoreactivity was absent in arcuate dopamine neurons from lactating rats 
suckling their pups (figure 8, panel B). These data demonstrate that FRA 
immunoreactivity can reveal reductions in activity as a result of the suckling 
stimulus within a specific inhibitory neuron population. The suckling stimulus, 
or consequences of hormonal changes resulting from suckling, appears to 
affect a great many brain systems in addition to the dopamine neurons. 
Analysis of FRA immunoreactivity throughout the brain, including the neocortex 
and hippocampus, revealed a marked reduction in baseline levels in lactating 
rats compared with cycling rats. An example of the pattern of FRA staining in 
A. Diestrus 
B. Suckling 
□ TH 
■ TH+FRA 
FIGURE 8. FRA expression in the dopamine neurons of the arcuate nucleus 
in (A) a diestrus and (B) a lactating female rat FRA proteins, 
normally expressed within the dopamine neurons, are no longer 
expressed in suckling rats. 
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