06 July 2016

Pleasure with benefits

Stimulation of the pleasure center strengthened the immunity of mice

Oleg Lischuk, N+1, based on Medical Xpress: Tickling the brain can boost immunity: study

Israeli scientists have found that stimulating the brain's pleasure center enhances the immune response in mice. This may explain the effectiveness of placebo in the treatment of infections. The results of the work are published in the journal Nature Medicine (Ben-Shaanan et al., Activation of the reward system boosts innate and adaptive immunity).

To selectively activate the pleasure center, employees of the Israeli Institute of Technology in Haifa injected mice with a viral vector. This vector embedded synthetic receptors activated only by synthetic ligands (DREADDs) into dopaminergic neurons. By injecting mice with a substance acting on these receptors, the scientists optionally "turned on" the neurons of the ventral-tegmental area (OBE), an important part of the brain's pleasure center responsible for the feeling of pleasure.

The scientists analyzed the effect of direct activation of WTO neurons on immune cells in the blood and liver of animals. They observed a small but statistically significant activation of splenic B-lymphocytes, monocytes and macrophages (it was expressed in the expression of toll-like type 4 receptors, alpha chains of interleukin-2 receptors, activation factors of CD80 and CD86 T-lymphocytes). At the same time, there was no clear pro- or anti-inflammatory orientation of immune reactions.

With intraperitoneal administration of E. coli (Escherichia coli) in mice 24 hours after WTO stimulation, the level of capture (phagocytosis) of bacteria by macrophages and dendritic cells was approximately 2.5 times higher than in animals from the control group. The increased bactericidal activity of these cells was confirmed by incubating them in an E. coli culture on a nutrient medium and observing the inhibition of bacterial growth.

To test the effect of the brain's pleasure system on acquired immunity, scientists injected them with E. coli 24 hours after the activation of neurons. Three days later, the number of animals producing immunoglobulin increased in the spleen M (IgM) B lymphocytes, and in the blood the concentration of these antibodies specific to E. coli was 86 percent higher than in the control group. Intracellular production of pro-inflammatory interferon-gamma in helper T-lymphocytes also increased in the liver of experimental animals. After a week, the level of the listed markers of an enhanced immune response returned to the initial values.

Since dopamine from the brain's pleasure system does not penetrate the blood-brain barrier, researchers were interested in the signaling pathway that activates the immune system. The sympathetic nervous system seemed to be the most likely candidate, since it is associated with the WTO and innervates all lymphoid organs. Selectively destroying peripheral sympathetic neurons, scientists were convinced that the stimulation of the WTO ceased to activate innate and acquired immunity.

As it was shown earlier, the placebo effect is associated with positive expectations from treatment, in the formation of which the brain's pleasure system is involved. Thus, the shown effect of this system on the immune response may explain the effectiveness of placebo in the treatment of infections. In addition, the connection between the WTO and the immune system looks logical in evolutionary terms, since pleasure-inducing events, such as eating or sex, are often associated with the entry of pathogens into the body, requiring the activation of immunity, the scientists note.

Portal "Eternal youth" http://vechnayamolodost.ru  06.07.2016

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