, 2004). With a view to specifying the contribution of TR4 in the nervous system, here we report that mice with a selective deletion of TR4 in the CNS using an inducible Cre-dependent deletion approach have a remarkable pain and itch phenotype, which is

associated with loss of excitatory interneurons in the superficial dorsal horn of the spinal cord. The mice show dramatically reduced responses in a heat pain test, higher mechanical thresholds, and profound decreases in the pain behaviors produced by noxious chemical stimulation. The mice are also largely unresponsive to different pruritogens. Despite showing reduced pain behaviors that Alpelisib in vivo are organized at supraspinal levels, the mice have normal reflex responsiveness to noxious heat and normal tissue injury-induced heat and mechanical hypersensitivity. By contrast, nerve injury-induced mechanical hypersensitivity was lost. Our findings demonstrate not only that there are functionally distinct populations of excitatory interneurons of the superficial dorsal horn, which contribute to modality specificity in the processing of pain and itch messages, but also that activity of these interneurons is essential for the full expression of supraspinally-integrated pain and itch behaviors. To explore the consequence of TR4 deletion from CNS neurons,

we generated mice in which the translation start codon of Screening Library screening exons 4 and 5 of the TR4 gene (Nr2c2) was floxed by loxP sites. This construct was linearized and introduced into embryonic stem cells to obtain TR4-floxed chimeric mice ( Figure 1A). Accurate targeting was confirmed by PCR ( Figure 1B). Next, we crossed Nestin-Cre mice ( Bates et al., 1999) with the TR4-floxed mice to generate CNS specific conditional

knockout (cKO) mice. PCR ( Figure 1C) and RT-PCR ( Figure 1D) in spinal cord and the loss of TR4 immunoreactivity in spinal cord tissue from the mutant mice, compared to its apparently ubiquitous neuronal expression in the spinal cord of wild-type (WT) mice, confirmed deletion of the TR4 gene ( Figure 1E). Thalidomide Consistent with findings after global TR4 deletion (Chen et al., 2007; Collins et al., 2004), we found that litters included equal numbers of male and female offspring, but both male and female TR4 cKO mice are ∼20% smaller in size compared to their WT counterparts (see Figure S1A available online). In contrast to the earlier report (Chen et al., 2005), we found that TR4 cKO mice had no difficulty negotiating an accelerating rotarod (Figure S1B). On the other hand, on average the cKO mice were impaired on the ledge test (Schaefer et al., 2000; Figure S1C). Although some of the mutant mice remained on the ledge for the 60 s test period, others did not. It is our impression that the mice did not fall from the ledge, but rather jumped.