Cannabinoids in parkinsonism (PD Congress report)

Subject: Cannabinoids in parkinsonism (PD Congress report)

Date: 8/1/1999

1. Cannabinoid receptor binding in the substantia nigra of MPTP-lesioned macaques displaying L-dopa-induced dyskinesia
MB O'Byrne, C Kobylecki, AR Crossman, JM Brotchie
P-MO-147

Primates with apomorphine-induced dyskinesias have reduced binding of the cannabinoid receptor antagonist SR141716A in the substantia nigra pars compacta, according to this report. Binding was reduced 30% compared to lesioned non-dyskinetic animals. No significant changes were seen in the pallidum or striatum.

2. The cannabinoid receptor antagonist SR141716A reduces L-dopa-induced dyskinesia in the MPTP-lesioned primate model of Parkinson's disease
M Hill, D Peggs, AR Crossman, JM Brotchie
P-MO-119

Cannabinoid receptor antagonism reduces levodopa-induced dyskinesias in marmosets without affecting the antiparkinson effect of levodopa, according to this report. In an adjunct experiment in reserpine-treated rats, administration of SR141716A reduced D1 agonist-induced locomotion, and increased D2 agonist-induced locomotion, in a dose-dependent manner. The authors suggest "Overactivation of the endocannabinoid modulation of the direct pathway may play a part in the generation of levodopa-induced dyskinesia," and suggest that cannabinoid receptors may be beneficial in dyskinesia treatment.

3. Marijuana chewing-induced improvements in Parkinson's disease
E Ruzicka
P-TU-136

This case report documents motor improvements from daily chewing of a single marijuana leaf in a 72-year-old man with Parkinson's disease. The patient was taking 400 mg levodopa/day when he began on marijuana, and continued his levodopa dose unchanged. After two months, he reported improved tremor and bradykinesia. He has continued for five years, with loss of benefit during two treatment suspension periods, and regain of benefit with recommencement of treatment. The author notes the patient has an unusually benign course of PD, that marijuana leaves have a different concentration and distribution of active ingredients than marijuana flowers, and that chewing is likely to produce different effects than smoking.

E-MOVE Editor: Richard Robinson, NASW, WE MOVE

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