Journal article
Microinjection of morphine into the rat medullary dorsal horn produces a dose-dependent increase in facial scratching
Brain research, Vol.695(2), pp.267-270
1995
DOI: 10.1016/0006-8993(95)00871-M
PMID: 8556343
Abstract
It has been proposed that opioids act at the level of the medulla to produce facial pruritus. Supporting this hypothesis, microinjection of μ-opioid receptor agonists into the medullary dorsal horn (MDH; trigeminal subnucleus caudalis) of monkeys produces facial scratching behavior. The present study sought to establish a rodent model of opioid-induced facial pruritus. To this end, morphine (0.1, 0.3 or 1.0 μg/0.2 μl) or saline (0.2 μl) was unilaterally microinjected into the MDH of male Sprague-Dawley rats. Behavior for the 20 min preceding and the 80 min after this microinjection was videotaped. Morphine produced dose-dependent increases in facial scratching behavior ipsilateral to the microinjections with the peak effect at 30–40 min after microinjection. Facial scratching continued for the entire 80 min post-microinjection test period. Morphine also produced a lesser degree of facial scratching contralateral to the microinjections. Increases in facial scratching ipsilateral to the microinjection of 0.3 μg morphine into the MDH were attenuated by 0.4 mg/kg s.c. naloxone. These findings support the hypothesis that the MDH is a critical site of action of opioid agonists in producing facial pruritus.
Details
- Title: Subtitle
- Microinjection of morphine into the rat medullary dorsal horn produces a dose-dependent increase in facial scratching
- Creators
- David A ThomasDonna L Hammond
- Resource Type
- Journal article
- Publication Details
- Brain research, Vol.695(2), pp.267-270
- Publisher
- Elsevier B.V
- DOI
- 10.1016/0006-8993(95)00871-M
- PMID
- 8556343
- ISSN
- 0006-8993
- eISSN
- 1872-6240
- Language
- English
- Date published
- 1995
- Academic Unit
- Iowa Neuroscience Institute; Nursing; Anesthesia; Neuroscience and Pharmacology
- Record Identifier
- 9984006462302771
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