Even mild inflammation in the middle of pregnancy can produce lasting autism-like changes in developing mice:
Reported consequences include autism-like behaviors, unusual brain growth, seizures, and greater sensitivity to ordinary sounds, touch, and other sensory experiences. These effects can continue into adulthood.
In the new study, published in Nature Communications, UCLA scientists found that one dose of rapamycin improved brain communication and behavior in the affected mice in about two hours. That response was far too fast for the drug to have repaired the underlying physical changes in the brain caused by maternal inflammation.
The researchers stressed that rapamycin should not be considered a practical treatment for these symptoms in people. Its benefits were temporary, repeated use can be toxic, and the study was conducted in mice.
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The drug works in part by reducing activity in the mTOR pathway, a biological signaling system that regulates cell growth and proliferation. Excessive mTOR activity has been linked to some autism-related conditions.
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Neurons that had been unusually active began firing more normally. The animals became less vulnerable to seizures. Brain regions that had not been communicating properly shifted toward more typical patterns. Repetitive behaviors, sensory sensitivity, and excessive responses to sensory input also declined.
All of these changes emerged within about two hours. Because physical remodeling of brain synapses generally takes longer, the scientists concluded that rapamycin was changing brain function rather than rebuilding the brain’s underlying structure.
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The strongest effects appeared in excitatory neurons, which stimulate activity in brain networks.
This suggests that the drug rapidly restored a healthier balance in neuronal excitability rather than repairing structural differences formed during early development.