“Positive expectations contribute to the clinical benefits of the placebo effect. Such positive expectations are mediated by the brain’s reward system; however, it remains unknown whether and how reward system activation affects the body’s physiology and, specifically, immunity.” Here the authors show that activation of the ventral tegmental area (VTA), a key component of the reward system, strengthens immunological host defense. Activation of dopaminergic neurons in the mouse VTA was followed by characterization of the subsequent immune response after exposure to bacteria (Escherichia coli), using time-of-flight mass cytometry and functional assays. The authors found a causal relationship between activity of the VTA and the immune response to bacterial infection. By chemically ablating the sympathetic nervous system, they also showed that the reward system’s effects on immunity are, at least partly, mediated by the sympathetic nervous system.
Ben-Shaanan TL, Azulay-Debby H, Dubovik T, Starosvetsky E, Korin B, Schiller M, Green NL, Admon Y, Hakim F, Shen-Orr SS, Rolls A: Activation of the reward system boosts innate and adaptive immunity. Nature Medicine [Epub ahead of print, July 4, 2016; doi: 10.1038/nm.4133 ].