To nail down the link, the 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 viruses were injected into the striata of knockout mice, those getting the fusion gene and beginning to express SAPAP3 saw the excessive grooming markedly reduced, from about 70 bouts per hour in the control mice to fewer than 30. The difference was significant at P<0.01.
"Since this is the first study to directly link OCD-like behaviors to abnormalities in the glutamate system in a specific brain circuit, it may lead to new targets for drug development," Dr. Feng said.
The research "sharpens our focus" on the frontal-striatal-thalamic circuits as possible sources of OCD, commented Steven Hyman, M.D., of Harvard, a former director of the National Institute of Mental Health.