How Social Isolation Transforms The Brain


Source: California Institute of Technology

Summary: Researchers have discovered that social isolation causes the build-up of a particular chemical in the brain, and that blocking this chemical eliminates the negative effects of isolation.


Chronic social isolation has debilitating effects on mental health in mammals for example, it is often associated with depression and post-traumatic stress disorder in humans. In a previous study of the Drosophila fly, researchers had discovered that a particular neurochemical called tachykinin plays a role in promoting aggression in socially isolated flies. Tachykinin is a neuropeptide, a short protein molecule that is released from certain neurons when they are activated. Neuropeptides bind to specific receptors on other neurons, altering their physiological properties and thereby influencing neural circuit function. Researchers from the California Institute of Technology have discovered that social isolation causes the build-up of a particular chemical in the brain, and that blocking this chemical eliminates the negative effects of isolation. The study findings were published in the journal Cell.

A state of complete or near-complete lack of contact between an individual and society.

Artist’s depiction of an isolated brain. Credit: Maayan Harel

To investigate whether the role of tachykinin in controlling social isolation-induced aggression might be evolutionarily conserved from insects to mammals, the research team turned to laboratory mice. In mice, the tachykinin gene Tac2 encodes a neuropeptide called neurokinin B (NkB). Tac2/NkB is produced by neurons in specific regions of the mouse brain such as the amygdala and hypothalamus, which are involved in emotional and social behavior. They found that chronic isolation leads to an increase in Tac2 gene expression and the production of NkB throughout the brain. However, administration of a drug that chemically blocks NkB-specific receptors enabled the stressed mice to behave normally, eliminating the negative effects of social isolation.

Postdoctoral scholar, Moriel Zelikowsky said, “When looking at the treatment of mental health disorders, we traditionally focus on targeting broad neurotransmitter systems like serotonin and dopamine that circulate widely throughout the brain. Manipulating these systems broadly can lead to unwanted side effects. So, being able to precisely and locally modify a neuropeptide-like Tac2 is a promising approach to mental health treatments.”


More Information: Moriel Zelikowsky et al, “The Neuropeptide Tac2 Controls a Distributed Brain State Induced by Chronic Social Isolation Stress” Cell (2018). DOI: 10.1016/j.cell.2018.03.037


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