We used the cheek model of itch and pain in rats to determine the dose-response relationships for intradermal injection of serotonin and α methylserotonin on scratching behavior. We also determined the dose-related effects of intracisternally injected morphine on scratching, effects that were greatly reduced by administration of the opiate antagonist naloxone. We then examined the interactions of intradermal injection of serotonin and intracisternal injection of morphine on scratching and found that the two procedures act synergistically to increase itch. These results suggest that morphine applied to the CNS is capable of producing itch and greatly increasing itch originating in the skin (hyperknesis).
|Original language||English (US)|
|Number of pages||9|
|State||Published - Aug 22 2014|
Bibliographical noteFunding Information:
We thank H. Truong, B. Lipshetz and C. Hosfield for valuable technical assistance, N. Jansen and Drs. C.N. Honda, D.A. Simone and G.L. Wilcox for critically reading an early version of this manuscript. This work was supported by NIH grants P01 NS047399 , NINDS Core funding NS062158, and F31 NS077554 to HRM.
- Intracisternal injection