Rats susceptible to anhedonia, a core symptom of depression, possess more serotonin neurons after being exposed to chronic stress, but the effect can be reversed through amygdala activation, according to new research in JNeurosci.
Some people are resistant to depression and anhedonia, or lack of pleasure, even when exposed to chronic stress. To measure susceptibility to anhedonia, Prakash et al. trained rats to activate an electrode that stimulated reward circuits in their brain, causing feelings of pleasure. The rats experienced social stress once a day and then were given access to self-stimulation fifteen minutes later. In rats susceptible to anhedonia, the stress dramatically increased the intensity of stimulation needed to feel pleasure, while it had little effect on the resilient rats.
Compared to the resilient rats, the susceptible rats had more serotonin neurons in the ventral part of their dorsal raphe nucleus, an area of the brain involved in regulating stress and reward. This increase is due to the recruitment of non-serotonin signaling neurons. When the researchers activated neurons in the central amygdala to prevent the increase in serotonin signaling, the rats experienced reduced effects from social stress.
Understanding the molecular thumbprint of depression susceptibility could lead to treatments that induce resilience in the face of chronic stress.
Manuscript title: Serotonergic Plasticity in the Dorsal Raphe Nucleus Characterizes Susceptibility and Resilience to Anhedonia
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JNeurosci, the Society for Neuroscience's first journal, was launched in 1981 as a means to communicate the findings of the highest quality neuroscience research to the growing field. Today, the journal remains committed to publishing cutting-edge neuroscience that will have an immediate and lasting scientific impact, while responding to authors' changing publishing needs, representing breadth of the field and diversity in authorship.
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The Society for Neuroscience is the world's largest organization of scientists and physicians devoted to understanding the brain and nervous system. The nonprofit organization, founded in 1969, now has nearly 37,000 members in more than 90 countries and over 130 chapters worldwide.