Neurotransmitters are chemical substances that jump from the end of one nerve cell to the beginning of the next. By doing so, neurological impulses are transmitted throughout the nervous system, sending signals to the body to open the eyes, feel hunger, smile at a baby, jump from snakes, and even how to learn and remember.
One such neurotransmitter is glutamate, important to the study of autism because of its influence on learning and memory. It works sort of like a volume control on the brain activities governing memory and learning.
Each brain cell has glutamate receptors inside and outside the cell but their interaction has been poorly understood until a study at the Washington University in St. Louis (Missouri) School of Medicine revealed that a specific glutamate receptor — mGlu5 — is more active inside than outside of the cell.
Receptors receive signals from neurotransmitters, hormones, toxins, and other elements and then signal the cell how to respond. The mGlu5 receptor responds only to glutamate.
The generally accepted understanding of how receptors work has been that the receptors on the outside of the cell are on the job, actively working and ready to catch signals coming from its matching messenger element. The receptors inside the cell were thought to be to be off the clock, either just transferred from outside the cell to rest inside or waiting to go to work on the outside.
The study's senior investigator, Dr. Karen O'Malley, a neurobiology professor, used brain cells in a petri dish to discover how the mGlu5 receptors inside the cell lower the volume at which cells communicate. Intercellular communication can be exaggerated for autism patients. Her study identified 50% to 90% more receptors inside the brain cells than outside them.
The study also revealed that the mGlu5 receptors on the surface of the cell send different messages than those inside the cell. Previous studies of mGlu5 receptors focused only on the receptors outside the cell.
Using scientifically historical data on the action of mGlu5 receptors on the cell's surface, pharmaceutical companies developed drugs that would lower the volume of the surface receptors as a means of controlling autistic behavior. No studies have been conducted to determine if or how these pharmaceuticals affect inside mGlu5 receptors.
In recent years, more than 20 types of brain cell receptors have been discovered to exist in high numbers inside cells as well as on the surface. O'Malley says, "This should be a factor we consider when we design drugs to target brain cell receptors. Do we want to reach cell surface receptors, receptors inside the cell, or both?"
Source: Purdy, Michael C. "New clue to autism found inside brain cells." Washington University in St. Louis Newsroom. Washington University in St. Louis. Mar 26, 2014. Web. Apr 10, 2014.