Neuroprotection and reduction of glial reaction by cannabidiol treatment after sciatic nerve transection in neonatal rats

In neonatal rats, the transection of a peripheral nerve leads to an intense retrograde degeneration of both motor and sensory neurons. Most of the axotomy-induced neuronal loss is a result of apoptotic processes. The clinical use of neurotrophic factors is difficult due to side effects and elevated costs, but other molecules might be effective and more easily obtained. Among them, some are derived from Cannabis sativa. Cannabidiol (CBD) is the major non-psychotropic component found on the surface of such plant leaves. The present study aimed to investigate the neuroprotective potential of CBD. Thus, 2-day-old Wistar rats were divided into the following experimental groups: sciatic nerve axotomy + CBD treatment (CBD group), axotomy + vehicle treatment (phosphate buffer group) and a control group (no-treatment group). The results were analysed by Nissl staining, immunohistochemistry and terminal deoxynucleotidyl transferase dUTP nick end labeling at 5days post-lesion. Neuronal counting revealed both motor and sensory neuron rescue following treatment with CBD (15 and 30mg/kg). Immunohistochemical analysis (obtained by synaptophysin staining) revealed 30% greater synaptic preservation within the spinal cord in the CBD-treated group. CBD administration decreased the astroglial and microglial reaction by 30 and 27%, respectively, as seen by glial fibrillary acidic protein and ionised calcium binding adaptor molecule 1 immunolabeling quantification. In line with such results, the terminal deoxynucleotidyl transferase dUTP nick end labeling reaction revealed a reduction of apoptotic cells, mostly located in the spinal cord intermediate zone, where interneurons promote sensory-motor integration. The present results show that CBD possesses neuroprotective characteristics that may, in turn, be promising for future clinical use.