- Chronic pain-induced emotional dysfunction is associated with astrogliosis due to cortical delta-opioid receptor dysfunction. Narita, M., Kuzumaki, N., Narita, M., Kaneko, C., Hareyama, N., Miyatake, M., Shindo, K., Miyoshi, K., Nakajima, M., Nagumo, Y., Sato, F., Wachi, H., Seyama, Y., Suzuki, T. J. Neurochem. (2006)