For the very first time, scientists have developed a light-activated drug for treating Parkinson's disease directly in a targeted part of the brain.
The drug — which is activated by shining light down an optical fiber implanted in the brain — reduced Parkinson's symptoms and improved motor function in mice.
When activated by light, the drug — called MRS7145 — blocks a protein called the "adenosine A2A receptor."
Previous studies have already suggested that the adenosine A2A receptor is a promising target for brain disorders such as Parkinson's disease.
However, as the authors explain in their paper, adenosine receptors are located throughout the brain, making it difficult to use them for selecting and targeting only specific parts of the brain.
By allowing "the spatiotemporal control of receptor function," the new light-activated drug overcomes "some of these limitations," note the authors.
Parkinson's and photopharmacology
In excess of 10 million of the world's population has Parkinson's disease, including 1 million people in the United States alone.
The disease is life-long and gets worse with time. It mainly affects movement, producing tremors, stiffness, slowness, and problems with balance and coordination. Non-movement symptoms can also arise, such as constipation, disturbed sleep, depression, anxiety, and fatigue.
Parkinson's disease does not usually strike before the age of 50; only around 10 percent of cases are diagnosed at an earlier age.
It arises due to death of nerve cells, or neurons, in a part of the brain called the substantia nigra. These neurons make a chemical messenger called dopamine, which, among other things, is important for controlling movement.
The goal of many drugs intended to treat Parkinson's disease is to restore dopamine levels in the brain. The blocking of adenosine receptors has been suggested as a target for such treatments, because it can raise dopamine levels.
Photopharmacology is a relatively new medical field that develops drugs whose power can only be switched on and off using light.
The approach offers the possibility of controlling the precise location of drug release in the body, thereby limiting any off-target side effects. An example is the precise targeting of chemotherapy drugs to specific cancer cells.
It also allows precise timing of the release of the drug. The release of type 2 diabetes drugs that individuals can switch on and off as and when required is an example of this.
Precisely timed dosing is a distinct advantage in the use of drugs that gradually lose their efficacy and thus require bigger doses to work. This is what happens with levodopa, the most common drug for treating Parkinson's disease.
Courtesy: Medical News Today
