To find genes that may be behind the brain's responsiveness to SSRIs, the TAU researchers first applied the SSRI Paroxetine brand name Paxil to 80 sets of cells, or "cell lines," from the National Laboratory for the Genetics of Israeli Populations, a biobank of genetic information about Israeli citizens located at TAU's Sackler Faculty of Medicine and directed by Dr. Gurwitz. The TAU researchers then analyzed and compared the RNA profiles of the most and least responsive cell lines. A gene called CHL1 was produced at lower levels in the most responsive cell lines and at higher levels in the least responsive cell lines. Using a simple genetic test, doctors could one day use CHL1 as a biomarker to determine whether or not to prescribe SSRIs.
"We want to end up with a blood test that will allow us to tell a patient which drug is best for him," said Oved. "We are at the early stages, working on the cellular level. Next comes testing on animals and people."
Rethinking how antidepressants work
The TAU researchers also wanted to understand why CHL1 levels might predict responsiveness to SSRIs. To this end, they applied Paroxetine to human cell lines for three weeks the time it takes for a clinical response to SSRIs. They found that Paroxetine caused increased production of the gene ITGB3 whose protein product is thought to interact with CHL1 to promote the development of new neurons and synapses. The result is the repair of dysfunctional signaling in brain regions controlling mood, which may explain the action of SSRI antidepressants.
This explanation differs from the conventional theory that SSRIs directly relieve depression by inhibiting the reabsorption of the neurotransmitter serotonin in
|Contact: George Hunka|
American Friends of Tel Aviv University