A nasal spray containing a specially-developed protein peptide could form the basis for highly-targeted treatment for depression, new research from the Centre for Addiction and Mental Health (CAMH) has shown. The peptide, when delivered in spray from, was found to relieve symptoms of depression, with the lead researcher hopeful of little to no side-effects.

The protein peptide was originally developed in 2010 by Dr. Fang Liu, Senior Scientist in the Campbell Family Mental Health Research Institute at CAMH. While the peptide was found to be just as effective as conventional anti-depressants when tested on animals, when administered orally it was unable to cross the blood-brain barrier in sufficient concentrations and therefore had to be injected into the brain.

A grant from the Canadian Institute of Health Research then enabled Liu and a team of researchers to explore other methods of delivery. In administering the peptide in the form of a nasal spray, the team found that it was delivered to the right part of the brain to relieve depression-like symptoms in animals.

Dr Liu's team had previously found that a binding between two dopamine receptors, the D1 and D2 receptor complex, was higher in the brains of sufferers of major depression. The peptide works by interfering with the binding between these receptors, in effect, working as an anti-depressant.

Recently we have seen research efforts focus on nasal delivery systems for various vaccines as an alternative method of delivery, however, this does appear to be new territory for the area of mental illness.

"This study marks the first time a peptide treatment has been delivered through nasal passageways to treat depression," says Dr. Liu.

The delivery method aside, the spray also signifies a new type of treatment for the illness itself, as previous treatments for depression have depended on medications that block serotonin or norepinephrine transporters.

The team is now experimenting to determine whether or not they can improve the effectiveness of the treatment. They hope to be able to cause the peptide to break down more slowly and travel more quickly in the brain.

"This research brings us one step closer to clinical trials," says Dr. Liu.

The team's findings were published in the journal Neuropsychopharmacology.