As a result of a significant scientific breakthrough in neuroscience, researchers from New Orleans and their colleagues have discovered a new mechanism for transmitting nerve signals that occurs outside the cell and involves a unique "pain switch." This discovery changes our understanding of how pain receptors work in the brain and could lead to the development of safer painkillers that effectively relieve pain without the typical side effects.

A New Perspective on Phosphorylation

Phosphorylation—a key process that regulates protein function—has been well studied inside cells, but its role in the extracellular space has remained largely unknown. Scientists set out to determine whether this modification, which occurs on the outer surfaces of many synaptic proteins, affects signal transmission between nerve cells (synapses) or influences the organism’s behavior as a whole.

The Role of the VLK Enzyme

The researchers found that nerve cells interact outside the cell using an enzyme called VLK (vertebrate lonesome kinase). This enzyme modifies proteins in the space between neurons. When active neurons release VLK, it enhances the activity of pain receptors. According to neurobiologist Matthew Dalva from Tulane University, who led the study published in Science, this discovery "offers an entirely new perspective on how we can influence cell behavior and potentially provides a simpler way to develop drugs that act outside the cell rather than penetrating it."

Experiments on Mice

When the research team removed VLK from pain neurons in mice, the animals did not experience the usual pain after surgery but continued to perceive their environment normally. Conversely, increasing VLK levels in these neurons heightened pain responses.

In other words, the enzyme released by neurons can modify proteins on the surface of other cells and trigger pain signals without affecting normal movement or sensations.

Implications for Medicine

This discovery opens up a new approach to developing painkillers that act on cells from the outside rather than penetrating them. Targeting enzymes like VLK, instead of blocking synaptic receptors (which often causes side effects), could simplify the delivery of pain relief and make these medications safer.

However, before new drugs based on this discovery can be developed, further research is needed to fully understand the effects of targeting VLK and to determine how broadly this mechanism influences proteins involved in the nervous system. Scientists also plan to explore what potential this mechanism holds for treating other brain disorders beyond pain.