“…The value of the analysis of Fos expression to monitor the nociceptive activity of large neuronal populations is solid (Coggeshall, 2005) and is reinforced by the present findings. Fos expression was previously demonstrated at the spinal cord in several chronic pain models in the absence of additional stimulation, which also occurred in STZ rats (Williams et al, 1991;Kajander et al, 1996;Catheline et al, 1999;Tokunaga et al, 1999;Bester et al, 2000;Dai et al, 2001;Kosai et al, 2001;Tsai et al, 2002;Coggeshall, 2005;Jergova and Cizkova, 2005;Morgado and Tavares, 2007). In the brain of STZ rats, Fos expression was shown to increase in some regions (Zheng et al, 2002;Revsin et al, 2005) and decrease in others (Zheng et al, 2002;Jang et al, 2003;Gouty et al, 2003), showing that it cannot be a direct result of STZ or indicate putative physiological disturbances of diabetic animals.…”