“…Several human studies have reported on core temperature changes after spinal opioid administrations, but only a few animal studies have investigated the role of spinal opioid receptors in this respect (Dib, Cormareche-Leydier, & Cabanac, 1982;Martin & Naruse, 1982;Rudy & Yaksh, 1977;Ryan, Price, Warriner, & Choi, 2012;Smith, Welch, Dombrowski, & Dewey, 1993). These studies investigate restrained animals and/or the thermistor is introduced into the colon causing significant stress responses, which leads to modified thermoregulation and motor behavior (Allen et al, 2007;Fukazawa et al, 2005;Martin & Naruse, 1982;Rudy & Yaksh, 1977). Sympathetic preganglionic neurons activated by glutamate via NMDA receptors also influence the core temperature (LoPachin & Rudy, 1982Rudy & Yaksh, 1977).…”