Chronic stress can cause inability to feel pleasure: here's how
Why don't I feel pleasure when under chronic stress? Let's talk about anhedonia
Have you noticed how disinclined toward pleasurable activities you become when under severe stress? Even when you indulge, you don't feel as much pleasure as you would on a normal day. The inability to feel pleasure is known as anhedonia, and you may wonder why that happens during stressful times.
Well, here's your answer.
When under chronic stress, POMC neurons in the brain are activated, resulting in anhedonia, which is the inability to feel pleasure, as well as despair, which is essentially depression. In humans, this can result in lower libido and reluctance to interact with friends. This, right here, is where chronic stress, depression, and anhedonia meet.
The impact of chronic stress on behavior
Chronic stress goes beyond just weariness; it can severely impact one's behavior. It does this by firing up a group of neurons in the brain called the proopiomelanocortin (POMC) neurons. These neurons are located in the hypothalamus, which regulates hunger, thirst, mood, sex drive, and sleep, among other functions. So it's easy to imagine that when those neurons are altered, these behavioral functions will also be altered.
In the study, the scientists exposed mice to 10 days of chronic stress. They found that the stressors increased the spontaneous firing of the POMC neurons, leading to anhedonia.
We know that mice have a natural love for sugar water. But when the POMC neurons were activated by chronic stress, that love waned. Even male mice, who normally like to sniff the urine of females in heat, no longer had any interest in doing so.
But here's the most important part of the study.
When the scientists inhibited the neurons from getting activated, there was little or no stress-induced behavioral change in the rodents. These results suggest that the POMC neurons are responsible for the depression, behavioral changes, and reduced interest in pleasurable things we feel when under chronic stress.
So if we could prevent these neurons from firing up, we may just have found a way around anhedonia and depression from chronic stress.
Still, that wasn't all.
The inverse relationship between POMC and AgRP neurons
Aside from POMP neurons, there are the AgRP neurons. The AgRP neurons are known for fighting off chronic stress and depression.
The team found that behavioral changes like anhedonia occur when AgRP activation goes down. But when the neurons are stimulated, the behavior stabilizes once more.
This suggests that chronic stress suppresses AgRP neurons and fires up POMC neurons, allowing behavioral changes to occur.
In essence, inhibiting POMC neurons and keeping AgRP neurons active would be key to fighting off anhedonia and depression when passing through chronic stress.
Apparently, targeting these specific neurons may be a potential treatment for these stress-induced problems. And that's great news!
The research was published in Nature.