Single Dose of Rapamycin Reverses Autism-Related Brain Changes in Adult Mice

A recent study revealed that inflammation during pregnancy can cause brain and behavioral alterations in offspring resembling some characteristics of autism spectrum disorder (ASD). However, these changes were shown to be temporarily reversible in adulthood through a single dose of the drug rapamycin.

Researchers from the University of California, Los Angeles (UCLA) Health Center conducted the study, demonstrating that mild inflammation in pregnant mice during mid-gestation led to offspring exhibiting repetitive behaviors, social interaction difficulties, heightened sensory sensitivity, abnormal brain growth, and an increased risk of seizures.

Administering one dose of rapamycin, an immunosuppressant drug medically used for years to prevent organ transplant rejection, notably improved brain activity and behavior in adult mice within approximately two hours.

The rapid improvement suggested that rapamycin does not act by reconstructing neural connections or altering brain structure but rather by modulating neuronal functions and regulating brain circuit activity.

How Rapamycin Affects Brain Function in Autism Models

Dr. Harley Kornblum, the study’s lead author and director of the Center for Intellectual and Developmental Disabilities Research at UCLA’s Semel Institute for Neuroscience and Human Behavior, stated that the findings indicate adult brains may possess greater capacity for adaptation and functional restoration than previously believed, even when changes originated early in development.

He added that these results encourage researchers to focus on targeting brain functions and neural circuits instead of concentrating solely on structural differences.

The study built on prior research linking maternal inflammation during pregnancy to a higher likelihood of autism-related traits in offspring. Other studies had also suggested that rapamycin could alleviate some symptoms in mice by inhibiting mTOR, a cellular pathway that regulates growth and activity within cells.

What the Experiment Revealed About Brain Activity and Behavior

In the new experiment, offspring of mice exposed to inflammation showed excessive activity in the mTOR pathway and disrupted communication between brain regions, alongside behaviors associated with autism.

Following a single rapamycin dose, the research team observed a reduction in abnormal neuronal activity, improved interregional brain communication, and decreases in repetitive behaviors and sensory hypersensitivity.

Dr. Janelle Le Belle, associate professor in UCLA’s Department of Neurosurgery and the study’s principal investigator, noted that these findings may open avenues for treating certain autism-related symptoms by enhancing brain function without altering fundamental structural differences.

Genetic Activity and Future Treatment Prospects

Gene activity analyses indicated that rapamycin helped reorganize genetic patterns linked to autism, epilepsy, and neuronal functions, supporting the notion that its effects involve restoring balance in brain activity.

Despite the promising outcomes, the researchers emphasized that rapamycin is not currently a treatment for autism in humans, as its effects were temporary and prolonged use could cause side effects due to its immunosuppressive properties.

Dr. Neil Harris, co-lead author of the study, highlighted that the significance of this research lies not in using rapamycin itself as a therapy but in identifying new therapeutic targets, such as regulating brain circuits and achieving better neuronal activity balance, to develop safer and more effective future treatments.

The study’s results were published in the journal Nature Communications.