The Therapeutic Effectiveness of Full Spectrum Hemp Oil Using a Chronic Neuropathic Pain Model

Abstract

Background: Few models exist that can control for placebo and expectancy effects commonly observed in clinical trials measuring 'Cannabis' pharmacodynamics. We used the Foramen Rotundum Inflammatory Constriction Trigeminal Infraorbital Nerve injury (FRICT-ION) model to measure the effect of "full-spectrum" whole plant extracted hemp oil on chronic neuropathic pain sensitivity in mice.

Methods: Male BALBc mice were submitted to the FRICT-ION chronic neuropathic pain model with oral insertion through an incision in the buccal/cheek crease of 3 mm of chromic gut suture (4-0). The suture, wedged along the V2 trigeminal nerve branch, creates a continuous irritation that develops into secondary mechanical hypersensitivity on the snout. Von Frey filament stimuli on the mouse whisker pad was used to assess the mechanical pain threshold from 0-6 h following dosing among animals (n = 6) exposed to 5 μL of whole plant extracted hemp oil combined with a peanut butter vehicle (0.138 mg/kg), the vehicle alone (n = 3) 7 weeks post-surgery, or a naïve control condition (n = 3).

Results: Mechanical allodynia was alleviated within 1 h (d = 2.50, p < 0.001) with a peak reversal effect at 4 h (d = 7.21, p < 0.001) and remained significant throughout the 6 h observation window. There was no threshold change on contralateral whisker pad after hemp oil administration, demonstrating the localization of anesthetic response to affected areas.

Conclusion: Future research should focus on how whole plant extracted hemp oil affects multi-sensory and cognitive-attentional systems that process pain.

Keywords: Cannabis; allodynia; cannabidiol; endocannabinoids; hemp; pain.

Figure 1

Experimental Timeline.

Figure 2

Mechanical hypersensitivity in a chronic trigeminal neuropathic pain model and effects of hemp oil. (A) Effect of trigeminal nerve injury. The reduction in mechanical threshold latency response to von Frey fiber mechanical stimulation of the whisker pad is statistically significant for 12 weeks after FRICT-ION trigeminal nerve compression injury. (B) Effect of hemp oil ingestion. The efficacy of hemp oil administered in peanut butter was tested in week 7 post nerve injury in male mice. Mechanical threshold was tested hourly on the ipsilateral whisker pad. The data are presented as a mean ± SEM. Two-way ANOVA with Dunnett’s multiple comparisons test. For the graphs, asterisks (*) indicate p < 0.05 comparing the FRICT-ION + Hemp to naïve control and (***) p < 0.001 comparing the FRICT-ION to naïve control. Dagger (†) indicates p < 0.05 comparing the FRICT-ION + Hemp to FRICT-ION.