Can neuroimmune mechanisms explain the link between ultraviolet light (UV) exposure and addictive behavior?

Publication date: Available online 17 July 2018Source: Brain, Behavior, and ImmunityAuthor(s): Krystal Iacopetta, Lyndsey E. Collins-Praino, Femke T.A. Buisman-Pijlman, Mark R. HutchinsonAbstractHigh ultraviolet (UV) light exposure on the skin acts as a reinforcing stimulus, increasing sun-seeking behavior and even addiction-like sun seeking behavior. However, the physiological mechanisms that underlie this process remain to be defined. Here, we propose a novel hypothesis that neuroimmune signaling, arising from inflammatory responses in UV-damaged skin cells, causes potentiated signaling within the cortico-mesolimbic pathway, leading to increased sun-seeking behaviors. This hypothesized UV-induced, skin-to-brain signaling depends upon cell stress signals, termed alarmins, reaching the circulation, thereby triggering the activation of innate immune receptors, such as toll-like receptors (TLRs). This innate immune response is hypothesized to occur both peripherally and centrally, with the downstream signaling from TLR activation affecting both the endogenous opioid system and the mesolimbic dopamine pathway. As both neurotransmitter systems play a key role in the development of addiction behaviors through their actions at key brain regions, such as the nucleus accumbens (NAc), we hypothesize a novel connection between UV-induced inflammation and the activation of pathways that contribute to the development of addiction. This paper is a review of the existing literature to exam...

Source: Brain, Behavior, and Immunity - July 18, 2018 Category: Neurology Source Type: research