Physiological response to acute and chronic nociceptive stimulation are important for living organisms. In our laboratory, we generated transgenic rats expressing the arginine vasopressin (AVP) and enhanced green fluorescent protein (eGFP) fusion gene, and the c-fos and monomeric red fluorescent protein 1 (mRFP1) fusion gene in the central nervous system. We made it possible to visualize the pain response in the living cells. Using these transgenic rats, the aim of our studies is the elucidation of the physiological role of AVP after nociceptive stimulation and the pathophysiology of work-related pain. We describe the previous findings of nociceptive response, using these transgenic animals.