| In vivo: |
| J Neurosci. 2002 Jun 1;22(11):4720-7. | | Delta 9-tetrahydrocannabinol and cannabinol activate capsaicin-sensitive sensory nerves via a CB1 and CB2 cannabinoid receptor-independent mechanism.[Pubmed: 12040079 ] | Although Delta(9)-tetrahydroCannabinol (THC) produces analgesia, its effects on nociceptive primary afferents are unknown. These neurons participate not only in pain signaling but also in the local response to tissue injury.
METHODS AND RESULTS:
Here, we show that THC and Cannabinol induce a CB(1)/CB(2) cannabinoid receptor-independent release of calcitonin gene-related peptide from capsaicin-sensitive perivascular sensory nerves. Other psychotropic cannabinoids cannot mimic this action. The vanilloid receptor antagonist ruthenium red abolishes the responses to THC and Cannabinol. However, the effect of THC on sensory nerves is intact in vanilloid receptor subtype 1 gene knock-out mice.
CONCLUSIONS:
The THC response depends on extracellular calcium but does not involve known voltage-operated calcium channels, glutamate receptors, or protein kinases A and C. These results may indicate the presence of a novel cannabinoid receptor/ion channel in the pain pathway. | | Arch Oral Biol . 2019 Aug;104:33-39. | | Cannabidiol, cannabinol and their combinations act as peripheral analgesics in a rat model of myofascial pain[Pubmed: 31158702] | | Abstract
Objective: This study investigated whether local intramuscular injection of non-psychoactive cannabinoids, cannabidiol (CBD), Cannabinol (CBN), cannabichromene (CBC) and their combinations can decrease nerve growth factor (NGF)-induced masticatory muscle sensitization in female rats.
Design: In awake rats, changes in mechanical sensitivity induced by intramuscular injection of NGF and cannabinoids were measured by applying an electronic von Frey hair over the masseter muscle to measure the withdrawal response. The effect of CBD (5 mg/ml) and CBN (1 mg/ml) or their combinations CBD/CBN (1:1 mg/ml or 5:1 mg/ml) were assessed. To confirm a peripheral action, electrophysiological experiments were undertaken in anesthetized rats to examine whether intramuscular injections of CBD (5 mg/ml) and CBN (1 mg/ml) altered the mechanical threshold of masticatory muscle mechanoreceptors.
Results: In behavioral experiments, CBD (5 mg/ml) or CBN (1 mg/ml) decreased NGF-induced mechanical sensitization. Combinations of CBD/CBN induced a longer-lasting reduction of mechanical sensitization than either compound alone. No significant change in mechanical withdrawal threshold was observed in the contralateral masseter muscles and no impairment of motor function was found with the inverted screen test after any of the treatments. Consistent with behavioral results, CBD (5 mg/ml), CBN (1 mg/ml) and the combination of CBD/CBN (1:1 mg/ml) increased the mechanical threshold of masseter muscle mechanoreceptors. However, combining CBD/CBN (5:1 mg/ml) at a higher ratio reduced the duration of this effect. This may indicate an inhibitory effect of higher concentrations of CBD on CBN.
Conclusions: These results suggest that peripheral application of these non-psychoactive cannabinoids may provide analgesic relief for chronic muscle pain disorders such as temporomandibular disorders and fibromyalgia without central side effects.
Keywords: Cannabichromene; Cannabidiol; Cannabinoid receptors; Cannabinol; Masseter muscle; Nerve growth factor. |
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