The role of endocannabinoids in nonpharmacological addiction

Several rewarding behaviors such as eating, sexual activity, parenting, nursing, play activity, and social interactions are essential for development and survival and, as such, are conserved strongly in evolution. These behaviors produce pleasure, increase wellness, and represent satisfying experiences with a high reward value. Similarly to the chemical rewarding stimuli (i.e., substances of abuse), these natural behaviors activate the brain reward circuit, i.e., the network of structures responsible for pleasure, motivation, and reinforcement learning. Growing evidence indicate that some of these pleasant, rewarding behavior as well as gambling or exercising can develop into compulsive behaviors that are difficult to contain and to stop before the onset of harmful consequences. Cannabinoid receptors are widely expressed in the brain areas regulating reward and motivated behaviors, and the endocannabinoid system modulates numerous physiological functions of the nervous system, including the complex machinery that regulates gratification and perception of pleasure. In this chapter, we examine the role of the endocannabinoid system in modulating behaviors that directly or indirectly activate these brain reward pathways and that, hence, may deteriorate into behavioral addictions.