Cannabinoid 2 Receptor- and Beta Arrestin 2-Dependent Upregulation of Serotonin 2A Receptors

Abstract

Recent evidence suggests that cannabinoid receptor agonists may regulate serotonin 2A (5-HT2A) receptor neurotransmission in the brain, although no molecular mechanism has been identified. Here, we present experimental evidence that sustained treatment with a non-selective cannabinoid agonist (CP 55,940) or selective CB2 receptor agonists (JWH 133 or GP 1a) upregulate 5-HT2A receptors in a neuronal cell line. Furthermore, this cannabinoid receptor agonist-induced upregulation of 5-HT2A receptors was prevented in cells stably transfected with either CB2 or β-Arrestin 2 shRNA lentiviral particles. Additionally, inhibition of clathrin-mediated endocytosis also prevented the cannabinoid receptor-induced upregulation of 5-HT2A receptors. Our results indicate that cannabinoid agonists might upregulate 5-HT2A receptors by a mechanism that requires CB2 receptors and β-Arrestin 2 in cells that express both CB2 and 5-HT2A receptors. 5-HT2A receptors have been associated with several physiological functions and neuropsychiatric disorders such as stress response, anxiety & depression and schizophrenia. Therefore, these results might provide a molecular mechanism by which activation of cannabinoid receptors might be relevant to some cognitive and mood disorders in humans.