Depressant and excitant effects of intraspinal microinjections of morphine and methionine-enkephalin in the cat
The effects of intraspinal microinjections of morphine (10 μg) and methionine-enkephalin (Met-enkephalin) (5 μg) on the C-fiber and polysynaptic reflexes in the acute decerebrate low spinal cat were investigated. Microinjected into the dorsal horn, morphine and Met-enkephalin depressed the nocicepti...
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Veröffentlicht in: | Brain research 1980-09, Vol.196 (2), p.455-465 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The effects of intraspinal microinjections of morphine (10 μg) and methionine-enkephalin (Met-enkephalin) (5 μg) on the C-fiber and polysynaptic reflexes in the acute decerebrate low spinal cat were investigated. Microinjected into the dorsal horn, morphine and Met-enkephalin depressed the nociceptive C-fiber reflex (CFR) without altering the short latency polysynaptic reflex. Microinjected into the ventral horn, morphine and Met-enkephalin facilitated the C-fiber and polysynaptic reflexes. Pretreatment of the cats with intravenous naltrexone (2 mg/kg) antagonized the depressant effects produced by dorsal horn intraspinal microinjections of morphine and Met-enkephalin. The excitant effects of ventral horn microinjections of morphine were not antagonized by naltrexone (2 mg/kg). These results support a hypothesis that the analgesic effects of morphine at the spinal cord level are due to interactions with opiate receptors in the dorsal horn. |
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ISSN: | 0006-8993 1872-6240 |
DOI: | 10.1016/0006-8993(80)90409-6 |