Article by Ricardo Oliveira. Lift
Brain ischemia is the medical phenomenon whereby a reduction of blood supply to the brain – usually due to stroke or cardiac arrest – leads to cerebral tissue damage. It is a leading cause of death and disability worldwide and, despite intense research efforts, there are still no good treatment options for it. Such failure has been attributed, in part, to a narrow focus by researchers on individual biological targets or behavioral outcomes.
Instead of being caused by a single process, brain ischemia lesions result from the conflagration of several biological processes – cellular excitation, inflammation, and oxidative stress — and result in a myriad of pathological markers such as changes in neuronal loss, in neuroplasticity, white matter composition, and protein synthesis. Surviving patients can also experience a multitude of mental sequelae such as cognitive decline, depression, and anxiety disorders. Instead of focusing on single lesion markers or recovery outcomes, studies ought to look at the condition as a whole.
At least this is the position defended by a team of Brazilian researchers who recently concluded an extensive clinical assay of the effects of Cannabidiol (CBD) in a mouse model of brain ischemia. The study was led by Dr. Rúbia Maria de Oliveira, and its promising results have just appeared in the journal Progress in Neuropsychopharmacology & Biological Psychiatry.
Two to three month old male mice were operated on, being anesthetized while their neck carotid arteries were pinched for 20 minutes to emulate brain ischemia. The animals were divided into three groups. One received abdominal injections of 10 mg/kg CBD 30 minutes before and 3, 24, and 48 hours after the surgery; while two control groups, one which underwent normal surgery (ischemic) and another that did not (nonischemic), received an inert solution under the same regimen.
In the following 21 days, the animals undertook a series of behavioral and cognitive tests that measured changes in general locomotor activity, anxiety, spatial memory, and depressive-like behavior. At the end of the study, the mice were sacrificed and their brains extracted for analysis of changes in neural architecture and immunity responses.
There was a general behavioral recovery in association with CBD administration. The ischemic group showed signals of anxiety compared to the nonischemic group, by averting exposure in open parts of the arena, an effect that was reversed in the CBD group. A similar trend was observed in spatial recognition tests, where CBD reduced the likelihood of rats not discriminating a new part of the maze and reversed an impairment in recognizing a change in the position of a familiar object. Finally, CBD also prevented the depressive-like behavior (inferred from reduced behavioral mobility when rats had to keep swimming to stay afloat), which was observed in the ischemic group. The general locomotor activity was not altered in any of the groups.