Effect of Cannabinoids and Stress on Motor Maps and Behaviour
Date
2015-09-17
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Abstract
Motor maps exhibit experience dependent changes and are therefore sensitive to the type and amount of neurotransmitters present in the motor cortex and changes in motor map expression often results in impairments of skilled behaviour. Endocannabinoids have been shown to affect spinal locomotion and stress has been shown to affect spontaneous locomotion therefore, the effect of cannabinoid signaling and stress on motor map expression and behaviour was examined. The first study determined that cannabinoid 1 receptor (CB1R) signaling dampened motor map expression and that both anandamide (AEA) and 2-arachidonoylglycerol (2-AG) contributed to this effect. Activation of CB1R signaling did not affect skilled reaching task performance. However, a lack of cannabinoid signaling resulted in impairment on performing the reaching motion. The second study characterized acute and repeated stress effects on motor map expression. Acute stress did not alter map expression while repeated stress decreased forelimb map expression and resulted in skilled motor behaviour deficits. It was then established that 2-AG mediates the stress effects seen on motor map expression. The last study observed the effects of delta-9-tetrahydrocannabinol (THC) on motor map expression as well as skilled and unskilled behaviour. It was discovered that THC dose dependently affected motor map expression in that a low dose of THC increased map expression while higher doses decreased forelimb map expression. THC decreased the number of reach attempts made in one 15 minute reach training session but did not impair the execution of reaching behaviour. Unskilled behaviour was assessed using the bar task, rotorod, horizontal ladder rung walking task and the open field test. No differences were found between rats that received THC and rats that received DMSO on the rotorod, rung walking task and the open field test. The highest dose of THC used (2.5 mg/kg) resulted in a longer latency for removal of the forepaws from the bar in the bar task. This research is important and necessary due to increasing usage of cannabinoids for recreation as well as to treat neurological illness. The present findings suggest that endocannabinoids and repeated stress via 2-AG have a dampening effect on motor map expression.
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Neuroscience
Citation
Scullion, K. (2015). Effect of Cannabinoids and Stress on Motor Maps and Behaviour (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25792