Cannabidiol improves nonmotor symptoms, attenuates neuroinflammation and favors hippocampal newborn neuronal maturation in a rat model of Parkinsonism

Objective: To investigate the effects of cannabidiol (CBD) on emotional and cognitive symptoms in rats with intra-nigral 6-hydroxydopamine (6-OHDA) lesions.

Methods: Adult male Wistar rats received bilateral intranigral 6-OHDA infusions and were tested in a battery of behavioral paradigms to evaluate nonmotor symptoms. The brains were obtained to evaluate the effects of CBD on hippocampal neurogenesis.

Results: 6-hydroxydopamine-lesioned rats exhibited memory impairments and despair-like behavior in the novelty-suppressed feeding test and forced swim test, respectively. The animals also exhibited dopaminergic neuronal loss in the substantia nigra pars compacta (SNpc), striatum, and ventral tegmental area and a reduction of hippocampal neurogenesis. Cannabidiol decreased dopaminergic neuronal loss in the SNpc, reduced the mortality rate and decreased neuroinflammation in 6-OHDA-lesioned rats. In parallel, CBD prevented memory impairments and attenuated despair-like behavior that were induced by bilateral intranigral 6-OHDA lesions. Repeated treatment with CBD favored the neuronal maturation of newborn neurons in the hippocampus in Parkinsonian rats.

Conclusion: The present findings suggest a potential beneficial effect of CBD on nonmotor symptoms induced by intra-nigral 6-OHDA infusion in rats.