World News | How Chronic Stress Affects Behavior, Leads to Depression

WASHINGTON, Jan. 24 (PTI) — Chronic stress can affect behavior, leading to depression, reduced interest in things that used to bring us joy, and even post-traumatic stress disorder (PTSD), according to a new study in mice. ) And other issues.

Scientists have evidence that a group of neurons in the arcuate part of the brain (the hypothalamus) becomes hyperactive after long-term exposure to stress. Such behavioral problems arise when these proopiomelanocortin (POMC) neurons become hyperactive, and when the scientists reduce their activity, the behavior diminishes, the study said.

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According to the study, scientists at the Medical College of Georgia (MCG) at Augusta University studied the hypothalamus, a key neuron in the POMC population, that releases hormones and regulates functions such as hunger, thirst, mood, libido and sleep Respond to 10 days of chronic, unpredictable stress.

Chronic unpredictable stress is widely used to study the effects of stress exposure in animal models, in this case, including restraint, prolonged wet beds in inclined cages and social isolation, the study said.

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The scientists found that stressors increased the spontaneous firing of these POMC neurons in both male and female mice, said corresponding author Xin-Yun Lu.

The scientists report their findings in the journal Molecular Psychiatry.

When they directly activate neurons instead of allowing stress to increase their firing, this also leads to a marked inability to feel pleasure, known as anhedonia and behavioral hopelessness, which is essentially depression, the study said.

In humans, indicators of anhedonia may include no longer interacting with good friends and decreased libido. In mice, their usual liking for sugar water waned, and male mice, which normally enjoy sniffing female urine during estrus, also lost some interest, the study said.

Conversely, when the MCG scientists inhibited the neurons’ firing, it reduced these types of stress-induced behavioral changes in both sexes, the study said.

The results suggest that POMC neurons are “both necessary and sufficient” for increased susceptibility to stress, and that their increased firing is a driver of behavioral changes such as depression. In fact, stress significantly reduced inhibitory input to POMC neurons, Lu said.

POMC neurons are located in the arcuate nucleus (ARC) of the hypothalamus, which is thought to be important in how chronic stress affects behavior.

Occupying the same region is another population of neurons called AgRP neurons that are important in fending off chronic stress and depression, Lu and her team report in early 2021 in the journal Molecular Psychiatry, the study said. important.

In the face of chronic stress, Lu and her team report that as behavioral changes such as anhedonia occur, AgRP activation declines, and when they stimulate these neurons, the behavior is attenuated.

Her team also wanted to know how chronic stress affects POMC neurons, the study said.

AgRP neurons, best known for their role in finding food when we’re hungry, are known to have a yin-yang relationship with POMC neurons: for example, when AgRP activation goes up, POMC activation goes down.

“If you stimulate AgRP neurons, it can trigger immediate, robust feeding,” Lu said.

Food deprivation also increases the firing of these neurons. It is known that, when excited by a hunger signal, AgRP neurons send direct messages to POMC neurons to release the feeding brake.

The scientists’ research found that chronic stress disrupts the yin-yang balance between these two groups of neurons.

Although AgRP projections to POMC neurons are clearly important for their firing activity, the underlying mechanism may be the primary mechanism by which POMC neurons become hyperactive in response to chronic stress, Lu said.

The study was funded by the National Institutes of Health.

(This is an unedited and auto-generated story from a Syndicated News feed, the content body may not have been modified or edited by LatestLY staff)