How hunger shuts off chronic pain
When we feel long lasting pain such as an inflammatory pain from injury, it can be quite debilitating. It stops us from functioning optimally and completing many tasks.
Pain is one of the need states that an individual has to deal with along with other competing need states such as hunger, fear and thirst. But very little is known about how the brain prioritises these needs.
The researchers also found that a tiny subgroup of 300 AgRP neurons suppressed inflammatory pain significantly while acute pain responses remained intact.
According to researchers from the University of Pennsylvania, the brain has a way of suppressing chronic pain when an animal is hungry which allows the animal to go look for food.
The neuroscientists studied mice that hadn’t eaten for 24 hours and how they responded to either acute pain or longer-term inflammatory pain.
The scientists found that the mice still responded to sources of acute pain but seemed less responsive to inflammatory pain than mice that had been well-fed. Their behaviour to inflammatory pain was the same as mice given anti-inflammatory painkillers.
Hunger and pain were two competing responses in mice and to find out how the brain was prioritising these responses, the scientists experimentally turned on a group of neurons that are known to activate hunger called agouti-related protein (AgRP) neurons. They found that chronic pain subsided while acute pain responses stayed the same.
The researchers also found that a tiny subgroup of 300 AgRP neurons suppressed inflammatory pain significantly while acute pain responses remained intact.
Further experiments revealed the neurotransmitter, a molecule called NPY, is responsible for selectively blocking inflammatory pain responses.
Blocking receptors for NPY reversed the effects of hunger, and pain returned.
Acute pain responses are important for us as it protects our body and keeps us from staying in a dangerous situation. But by suppressing inflammatory pain when we are hungry, our brain allows us to prioritise hunger over pain which is very important for survival. This study also shows great potential for targeting inflammatory pain in individuals on future therapies.
Source: Cell
