The Journal of Neuroscience, December 1, 2001, 21(23):9499-9505
Absence of
-9-Tetrahydrocannabinol Dysphoric Effects in
Dynorphin-Deficient Mice
Andreas
Zimmer1, 2,
Emmanuel
Valjent3,
Monika
König1,
Anne M.
Zimmer1, 2,
Patricia
Robledo3,
Heidi
Hahn1,
Olga
Valverde3, and
Rafael
Maldonado3
1 Laboratory of Genetics, National Institute of Mental
Health, Bethesda, Maryland 20892, 2 Psychiatric Clinic,
University of Bonn, 53105 Bonn, Germany, and 3 Laboratori
de Neurofarmacologia, Facultat de Ciències de la Salut i de la
Vida, Universitat Pompeu Fabra, 08003 Barcelona, Spain
The involvement of dynorphin on
-9-tetrahydrocannabinol (THC)
and morphine responses has been investigated by using mice with a
targeted inactivation of the prodynorphin (Pdyn) gene. Dynorphin-deficient mice show specific changes in the behavioral effects of THC, including a reduction of spinal THC analgesia and the
absence of THC-induced conditioned place aversion. In contrast, acute
and chronic opioid effects were normal. The lack of negative
motivational effects of THC in the absence of dynorphin demonstrates
that this endogenous opioid peptide mediates the dysphoric effects of marijuana.
Key words:
cannabinoid; opioid; mice; mutation; withdrawal; addiction; place aversion
Copyright © 2001 Society for Neuroscience 0270-6474/01/21239499-07$05.00/0