While there were no differences between the groups prior to immersion or when warmed, immediately after removal from the warm water, the core body temperature of DTX-treated mice dropped significantly lower than that of saline-treated mice and took longer to recover (Figures 6C and 6E, on days 3 and 6 after saline/DTX treatment). Moreover, on day 6, core body temperature at baseline was significantly lower in DTX-treated mice when compared to saline-treated controls (Figure 6E). These data collectively

indicate that CGRPα DRG neurons play a critical role in thermoregulatory mechanisms after Selleckchem GSK1210151A whole-body cooling. In the same assay, DTX-treated mice repelled water to the same extent as saline-treated mice 3 days after saline/DTX treatment (Figure 6D) but retained significantly more water weight on day 6 (Figure 6F), suggesting a moderate impairment of fur barrier function. This impairment might be due to loss of CGRP-IR guard hair innervation (Figure S2). Guard hairs add a water repellent, oily sheen to the coat of furry mammals. And CGRP-IR primary afferents fire in response to guard hair displacement (Lawson et al., 2002; Woodbury et al., 2001). Given that DTX-treated mice had enhanced responses to multiple cold stimuli and had difficulty warming themselves

when cooled, we hypothesized that DTX-treated mice might prefer a warmer environment over a relatively cooler environment. To test this possibility, we monitored the amount of time saline- and DTX-treated mice spent on two surfaces NVP-AUY922 set at equivalent (25°C versus 25°C) or different (25°C versus PAK6 30°C; 20°C versus 30°C; 30°C versus 40°C) temperatures. The mice demonstrated no preference when the two surface temperatures were equivalent, as expected (Figures 6G and 6H). However, when surface temperatures differed, DTX-treated mice spent significantly more time on the warmer surfaces

(Figures 6G and 6H). This behavior was remarkably consistent between male and female mice and suggests that DTX-treated mice prefer warmer temperatures (or show enhanced avoidance of cooler temperatures). Since ablation of CGRPα DRG neurons enhanced behavioral sensitivity to cold but did not alter peripheral nerve responses to cold, this suggested that CGRPα DRG neuron ablation might instead alter central processing of temperature signals, at postsynaptic targets in the spinal cord. To assess central alterations in function, we measured baseline and agonist-evoked spontaneous excitatory postsynaptic current (EPSC) frequency in spinal cord slices from saline- and DTX-treated CGRPα-DTX+/− mice. We used capsaicin to activate TRPV1/heat-sensing afferents and icilin to activate TRPM8/cold-sensing afferents. These agonists are known to increase EPSC frequency in spinal neurons that are postsynaptic to TRPV1 and TRPM8 DRG neurons, respectively (Yang et al., 1998; Zheng et al., 2010).