It shouldn’t come as much of a surprise that chronic pain and depression often go hand-in-hand. The reason as to why this relationship exists, however, is not completely understood. A recent Japanese study has shed some light on this topic.
Authored by a team of researchers from Japan’s Hokkaido University, the study authors examined the neural pathways in a group of laboratory rats. In short, the neural pathways are simply the connections that form between nerve cells. For their study, the research team documented how chronic pain affected the functionality of these pathways.
What the authors found was that a specific pathway seemed to be particularly affected by pain. Specifically, they concluded that there was excessive signaling activity in the pathway connecting a brain region known as bed nucleus of the stria terminalis (BNST) to a region called ventral tegmental area (VTA). The signals that caught the eye of the authors are known as corticotropin-releasing factor (CRF) signals. CRF is a neuropeptide, or a protein-like molecule, which plays a key role in the onset of emotions such as anxiety and fear.
Turning Down the Noise
Given this observation, the study team decided to provide the rodents with a drug designed to mute excessive CRF signals. Sure enough, this paid quick dividends, as the amount of CRF signals subsided while the activity of dopamine neurons increased. The latter is an essential component of the brain’s reward system.
“Clinicians have known for a long time that chronic pain often leads to depression, however the brain mechanism for this was unclear,” stated study author Masabumi Minami, a Hokkaido University professor. “By clarifying the mechanism by which the brain reward system is continuously suppressed, we found the missing link between chronic pain and depression.”
Minami is confident that his team’s work could eventually be used to assist those struggling with both pain and emotional issues. “These findings could not only lead to improved treatment of emotional aspects of chronic pain, but also to new therapeutics for depressive disorders.”