Higher doses of cannabidiol (CBD) and tetrahydrocannabinol (THC) reduced cold hypersensitivity in mice with Parkinsonian features, while also producing favorable changes in several markers of oxidative stress, according to a new study published in The Journal of Neurobehavioral Sciences.
The study, published August 31, examined the effects of CBD and THC on pain sensitivity in a reserpine-induced mouse model. Researchers note that pain is a common non-motor symptom of Parkinson’s disease and can be difficult to manage with conventional treatments.
Researchers used 42 adult mice divided into seven groups of six. Parkinsonian features were induced using reserpine at 0.5 milligrams per kilogram for 10 days. The mice then received either CBD at 30 or 60 mg/kg, THC at 4 or 6 mg/kg, a combination of 60 mg/kg CBD and 6 mg/kg THC, or no cannabinoid treatment.
Pain sensitivity was measured using a cold tail-flick test in which part of each mouse’s tail was submerged in water at 4 degrees Celsius. Researchers measured how long it took the animals to withdraw their tails, with longer withdrawal times indicating reduced cold hypersensitivity.
Mice receiving reserpine alone had an average withdrawal latency of 18.5 seconds. Treatment with the higher CBD dose increased this to 46.75 seconds, while the higher THC dose produced an average latency of 57.75 seconds. Both increases were statistically significant compared with reserpine alone.
The lower THC dose and the CBD-THC combination also produced longer average withdrawal times, but those differences did not reach statistical significance.
Researchers also observed changes in oxidative stress biomarkers. Certain CBD, THC and combination treatments reduced malondialdehyde, a marker of lipid peroxidation, while higher-dose CBD, higher-dose THC and the combination significantly increased superoxide dismutase activity. Higher-dose THC and the CBD-THC combination also significantly increased reduced glutathione levels.
The authors conclude that selected CBD and THC regimens were associated with increased cold-withdrawal latency and favorable changes in oxidative stress markers, but said the findings do not establish CBD or THC as a treatment for Parkinson’s disease-associated pain and require further study.
