Researchers have accidentally came to an interesting finding while trying understand the function of brain proteins known as SAPAP, including SAPAP3, which plays a role in the glutamate chemical messenger system. They have found that the mice that lacked the protein showed excessive grooming to the point of causing skin damage and increased anxiety, resembling characteristics of human obsessive-compulsive disorder (OCD).

They tested the drug fluoxetine (Prozac) on those mice and noticed that it alleviated the symptoms in half of the mice, just like it did in humans.
Mice that lacked the gene for SAPAP3 were grooming themselves significantly more than wild-type mice even during times when they would normally be asleep. They also appeared to be more anxious and timid that their wild-type cousins.

Researchers were stunned with the parallels with OCD. After a six-days treatment with 5 mg/kg fluoxetine a day, the knockout mice had less severe symptoms.

In order to spot the link, researchers created a lentivirus that carried either the gene for green fluorescent protein (GFP) or a fusion of the GFP gene and that for SAPAP3. When the mice received the viruses, those who got the fusion gene began to express SAPAP3 also experienced reduced grooming, from about 70 bouts per hour in the control mice to fewer than 30.

Researchers hope that this finding may lead to new treatments especially because it’s the first time they had linked OCD-like behaviors to abnormalities in the glutamate system in a specific brain circuit.