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Acta Neuropsychiatr. 2016 Dec;28(6):321-326.

Descending serotonergic and noradrenergic systems do not regulate the antipruritic effects of cannabinoids.

Author information

1
Department of Medical Pharmacology, Faculty of Medicine,Trakya University,22030-Edirne,Turkey.

Abstract

BACKGROUND:

For centuries, cannabinoids have been known to be effective in pain states. Itch and pain are two sensations sharing a lot in common.

OBJECTIVE:

The goal of this research was to observe whether the cannabinoid agonist WIN 55,212-2 reduces serotonin-induced scratching behaviour and whether neurotoxic destruction of descending serotonergic and noradrenergic pathways mediate the antipruritic effect of WIN 55,212-2. Material and methods Scratching behaviour was induced by intradermal injection of serotonin (50 µg/50 µl/mouse) to Balb/c mice. The neurotoxins 5,7-dihydroxytryptamine (5,7-DHT, 50 μg/mouse) and 6-hydroxydopamine (6-OHDA, 20 μg/mouse) are applied intrathecally to deplete serotonin and noradrenaline in the spinal cord. WIN 55,212-2 (1, 3, 10 mg/kg, i.p.) dose-dependently attenuated serotonin-induced scratches. Neurotoxic destruction of neither the serotonergic nor the noradrenergic systems by 5,7-DHT and 6-OHDA, respectively, had any effect on the antipruritic action of WIN 55,212-2.

CONCLUSION:

Our findings indicate that cannabinoids dose-dependently reduce serotonin-induced scratching behaviour and neurotoxic destruction of descending inhibitory pathways does not mediate this antipruritic effect.

KEYWORDS:

212-2; WIN 55; cannabinoid system; descending inhibition; pruritus

PMID:
27805543
DOI:
10.1017/neu.2016.16
[Indexed for MEDLINE]

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