Contarino, A., Picetti, R., Matthes, H. W., Koob, G. F., Kieffer, B. L. and Gold, L. H.:Lack of reward and locomotor stimulation induced by heroin in mu-opioid receptor-deficient mice. Eur. J. Pharmacol., 446: 103-109, 2002.
Berrendero, F., Kieffer, B. L., Maldonado, R.:Attenuation of nicotine-induced antinociception, rewarding effects, and dependence in μ-opioid receptor knock-out mice. J. Neurosci., 22: 10935-10940, 2002.