Chronic treatment of rats with morphine caused tolerance to the membrane hyperpolarizing action of morphine in single locus coeruleus neurons in vitro. Tolerance was less pronounced for Try-D-Ala-Gly-MePhe-Gly-ol (DAGO) than for normorphine. No changes were found in affinity of naloxone for mu-receptors on these neurons, nor in the properties of the potassium conductance increase caused by mu-receptor activation. These results suggest that the mechanisms underlying tolerance involve either a reduction of the number of mu-receptors on each cell, or a reduced coupling of mu-receptors to potassium channels.
|Original language||English (US)|
|Number of pages||4|
|Journal||NIDA research monograph|
|State||Published - 1986|
ASJC Scopus subject areas
- Medicine (miscellaneous)