Figure 2. The lack of STAT3 activation in GFAP⁺ NSCs and astrocytes in Trpv1^−/− mouse brains during inflammation.

C57BL/6J mice received an icv administration of 30 ng/kg LPS and were sacrificed for STAT3 immunohistochemistry. (a,b) The nuclear translocation of STAT3 was observed in a large number of GFAP⁺ NSCs in sensory CVOs and in GFAP⁺ astrocytes in thermoregulatory hypothalamic subregions in Trpv1^+/+ mice 2 hr after the central LPS stimulation (top and middle panels in a), while the translocation of STAT3 was scarcely detected in Trpv1^−/− mouse brains (b). A three-dimensional image analysis demonstrated the occurrence of STAT3⁺ nuclei in GFAP⁺ NSCs and astrocytes (bottom panels in a). Arrowheads indicate STAT3⁺ nuclei in GFAP⁺ cells. Scale bars = 50 (top panels of a,b) and 10 (bottom panels of a) μm. (c) The quantitative analysis revealed that the number of STAT3⁺ GFAP⁺ cells in Trpv1^+/+ mouse brains was markedly elevated in sensory CVOs and hypothalamic thermoregulatory brain subregions after the central administration of 30 ng/kg LPS, while this number did not increase in Trpv1^−/− mice. ac, anterior commissure; 3V, 3^rd ventricle; Sol, solitary nucleus. Data (n = 4) were expressed as the mean (±s.e.m.). ^***P < 0.001 vs the vehicle in Trpv1^+/+ mice and ^###P < 0.001 between Trpv1^+/+ and Trpv1^−/− mice by ANOVA with Turkey’s post hoc tests.