TGF-β1 inhibited spinal peripheral nerve injury induced spinal microgliosis. Cell proliferation evoked by peripheral nerve injury was evidenced by an increase in BrdU+ cells in the spinal cord, ipsilateral to the nerve lesion, which was abolished by TGF-β1 treatment (A). Confocal images showing colocalization of BrdU (green nucleus staining) with microglial marker Iba-1 (red cytoplasm stain) revealed that the majority of dividing cells are microglia (B). The number of BrdU+ cells in the groups of animals treated or not with TGF-β1 was quantified in four different quadrants (C). Representative images of Iba-1+ cells in the spinal cord of naïve rats injured with saline and injured with TGF-β1 treatment depict the effects of TGF-β1 in reducing microglial cell density (D); further confirmed by quantitative analysis (E). Data are shown as means ± SEM. *p < 0.05, **p < 0.01, TGF-β1 treated vs. saline treated in their respective region. #p < 0.05, ipsi- vs. contra-lateral sides within the same group of injured-saline treated rats. Scale bar: 3A) 100 μm; 3B) 20 and 10 μm; 3D) 20 μm.