Role of cannabidiol in neuropsychiatric comorbidities in absence seizures

Abstract

Available anti-epileptic drugs are efficient enough to block seizures but do not treat comorbid psychiatric conditions such as anxiety, thus resulting in possible symptom aggravation. Since cannabidiol (CBD) has been recently approved in the USA and Europe for the treatment of two rare childhood types of epilepsy, and it is known to have anxiolytic effects this study aimed to evaluate its effects on anxiety in an animal model of childhood absence epilepsy (CAE) at a dose of 100 mg/kg. We used a polygenic model of CAE, the Genetic Absence Epilepsy Rats from Strasburg (GAERS), comparing with its non-epileptic control (NEC) rats and the original outbred strain, Wistar rats. Rats were injected with CBD (100 mg/kg) or vehicle prior to undergoing behavioural testing, i.e., the Hole-Board Test and the Elevated Plus Maze. It was observed that 100 mg/kg of CBD induced an anxiogenic effect in GAERS strain, with minimal effects on NEC and Wistar, contradicting the available evidence. This is possibly due to i) the high dose of CBD used here, ii) an effect of the vehicle considering that iii) GAERS rats used in control conditions showed a less anxious profile of those compared to other studies also from the same laboratory. This indicates that appropriate dose-response studies need to be done using a different vehicle to find an optimum dosage. Comparisons to other rat models would also be envisaged.