London, April 8 (IANS): Offering new insights into how depression and anxiety originate, scientists have now discovered a model to control serotonin signalling pathways either with blue or red light.

Serotonin is neurotransmitter primarily found in the gastrointestinal tract, platelets, and the central nervous system of animals, including humans.

It is believed that an imbalance in serotonin levels causes anxiety and depression.
One receptor, which is important for the regulation of serotonin levels in the brain, is the 5-HT1A receptor, the study found.

It belongs to a protein family called G protein coupled receptors (GPCRs).

These receptors can activate different signalling pathways in cells to support or suppress various signalling events, found the researchers.

Applying optogenetic methods the scientists used cone opsins from the mouse and human eye to control specifically serotonin signalling pathways either with blue or red light.

Optogenetics combine genetics and optics to control well-defined events within specific cells of living tissue.

The scientists also demonstrated that they were able to modulate mouse emotional behaviour using the light-activated receptors.

When they switched on the serotonergic signals by light in a certain brain area, the mice became less anxious.

“We hope that with the help of these optogenetic tools, we will be able to gain a better understanding about how anxiety and depression originate," said neuroscientist Olivia Masseck from Ruhr-Universitat Bochum in Germany.

The study appeared in the journal Neuron.