Neurons in a bow-shaped brain area get overactive after long stress exposure.
Chronic stress clearly has an affect on our behaviour. It causes issues such as sadness, decreased interest in formerly pleasurable activities, and even PTSD. Researchers now have proof that persistent stress causes a subpopulation of neurons in the bow-shaped region of the brain to become hyperactive. These kinds of behavioural issues arise when these POMC neurons are overly active. And when researchers lowered their activity, it lowered the abnormalities.
The American Psychological Association states that prolonged stress has an impact on every bodily system. Muscles tense as well to protect us from damage and suffering. Shortness of breath can be caused by stress, especially in people who already have respiratory disorders such as asthma. In the long run, it can raise the risk of hypertension, heart attack, and stroke. Additionally, can change the healthy bacteria in our stomach that aids digestion.
The National Institutes of Health provided funding for the study.
The study was published in the journal Molecular Psychiatry.
Indepth look into constant stress & depression:
The POMC neurons are located in the hypothalamic arcuate nucleus, or ARC. Its is a bow-shaped brain area that is previously known to be critical in how chronic stress impacts behaviour. Additional group of neurons, known as AgRP neurons, occupy the same location. And they are critical for resistance to chronic stress and depression.
The proopiomelanocortin, or POMC, neurons were studied in the hypothalamus . It is important for processes like hormone release and regulation of hunger, thirst, mood, sex drive, and sleep. The study was conducted with 10 days of constant, unpredictable stress. The effects of chronic unpredictable stress are frequently studied in animal models.
According to the study’s corresponding author, Xin-Yun Lu, MD, PhD, stressors increased the spontaneous firing of these POMC neurons in both male and female mice.
When scientists directly triggered the neurons they saw an apparent inability to feel pleasure. The conditions is known as anhedonia, aka behavioural despair, or depression.
In humans, signs of anhedonia include a decrease of libido and a lack of interaction with close pals.
Mice lose some of their usual enthusiasm for sugar water, and male mice who often enjoy sniffing females’ urine while they are in heat do the same. When the MCG researchers stopped the firing of neurons, it reduced these types of stress-induced behavioural alterations in both sexes.
The findings show that POMC neurons are absolutely required and sufficient to increase vulnerability to stress. And their increased firing is a key factor in the development of behavioural abnormalities like depression. Stress visibly reduced the inhibitory inputs to POMC neurons.
Study take away:
Potassium channels in POMC neurons are known to respond to a variety of different inputs. And when open, allow potassium to flow out of the cell, dampening neuronal activity.
The scientists hypothesise that stress also affects the potassium channels. And the opening those channels might be a possible targeted therapy to calm the erratically firing POMC neurons. However, the potential role of these potassium channels in POMC neurons in response to stress needs further study.
Parvathy Sukumaran 
