A recent study has shown that autistic mice models develop abnormal social behaviors after continuously experiencing seizures. The research findings, which were presented this past Tuesday in Boston at the Autism Consortium Research Symposium, add further evidence that seizures and autism are often linked. Furthermore, seizures can amplify the effects of various autism risk genes.
Matthew Anderson, associate professor of pathology at Beth Israel Deaconess Medical Center and lead investigator of the study, states, “It’s sort of a gene-environment interaction.” The researchers explored the link between autism and epilepsy, as one in three autistic individuals suffers from epilepsy as well. These men and women typically score much lower in tests for social and motor skills compared to those without epilepsy.
In order to explore the link, researchers injected healthy mice with pentylenetrazole, a chemical that induces seizures, once a day over the course of ten days. Over the course of the study, the mice experienced increasingly severe seizures. Furthermore, they began to prefer spending time with an inanimate object as opposed to another mouse, demonstrating a social impairment. Vaishnav Krishnan, postdoctoral fellow in Anderson’s lab, states that many mouse models of autism demonstrate the same social impairment evident in those experiencing seizures.
Although researchers cannot officially state that the social impairments stem from seizures and not the drug itself, Krishnan states that researchers have obtained very similar results using another drug that induces seizures. Furthermore, post-seizure, the mice showed dampened expression of an autism-linked gene called PTEN. The mice also showed an increase in the UBE3A expression after receiving the first drug dose. UBE3A is located in a chromosomal region that is duplicated in up to 3 percent of individuals with autism.
To further investigate the role of UBE3A in social behavior, researchers created mouse models that had either one or two extra copies of the gene. Their findings determined that the mice with two extra copies of the gene have impaired social abilities even in the absence of the seizure-inducing drug. Anderson states, “If they have this extra copy, their social preference is lost completely”. The next step for the researchers is to further investigate if seizures amplify other autistic symptoms, aside from issues with social behaviors, in mice. They also hope to pin down the specific brain regions that are involved in the process.