Differential effects of morphine- and cocaine-induced nNOS immunoreactivity in the dentate gyrus of hippocampus of mice lacking mu-opioid receptors.
Neurosci Lett
; 395(2): 98-102, 2006 Mar 06.
Article
in En
| MEDLINE
| ID: mdl-16300892
ABSTRACT
This study investigated the expression of nNOS after repeated morphine or cocaine administration in order to determine if nNOS (neuronal nitric oxide synthase) is involved in the morphine- or cocaine-induced behavioral sensitization in mu-opioid receptor knockout (MOR(-/-)) mice. Higher numbers of nNOS-positive cells were observed in the dentate gyrus of the hippocampus (DG) of the wild-type (MOR(+/+)) mice repeatedly treated with either morphine or cocaine than in the saline treated MOR(+/+) mice (morphine, +122%; cocaine, +82%). Moreover, the MOR(-/-) mice also showed significantly higher morphine- or cocaine-induced nNOS expression levels in the DG than in the saline treated MOR(+/+) mice (morphine, +234%; cocaine, +54%). The MOR(-/-) mice showed a significantly higher morphine-induced nNOS expression level (+103%) or a lower cocaine-induced nNOS expression level (+38%) in the DG than in the morphine- or cocaine-treated MOR(+/+) mice. These results suggest that morphine and cocaine sensitization is differentially regulated by the mu-opioid receptors in MOR(-/-) mice via the nNOS systems in the DG.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Cocaine
/
Receptors, Opioid, mu
/
Dopamine Uptake Inhibitors
/
Dentate Gyrus
/
Nitric Oxide Synthase Type I
/
Morphine
/
Narcotics
Limits:
Animals
Language:
En
Journal:
Neurosci Lett
Year:
2006
Document type:
Article