Rapamycin reverses impaired social interaction in mouse models of tuberous sclerosis complex.
Impairment of reciprocal social interaction is a core symptom of autism spectrum disorder.
Genetic disorders frequently accompany autism spectrum disorder, such as tuberous sclerosis complex caused by haploinsufficiency of the TSC1 and TSC2 genes. Accumulating evidence implicates a relationship between autism spectrum disorder and signal transduction that involves tuberous sclerosis complex 1, tuberous sclerosis complex 2 and mammalian target of rapamycin.
Here we show behavioural abnormalities relevant to autism spectrum disorder and their recovery by the mammalian target of rapamycin inhibitor rapamycin in mouse models of tuberous sclerosis complex. In Tsc2(+/-) mice, we find enhanced transcription of multiple genes involved in mammalian target of rapamycin signalling, which is dependent on activated mammalian target of rapamycin signalling with a minimal influence of Akt.
The findings indicate a crucial role of mammalian target of rapamycin signalling in deficient social behaviour in mouse models of tuberous sclerosis complex, supporting the notion that mammalian target of rapamycin inhibitors may be useful for the pharmacological treatment of autism spectrum disorder associated with tuberous sclerosis complex and other conditions that result from dysregulated mammalian target of rapamycin signalling.
We already know that there’s some kind of connection between epilepsy and autism: Children who have seizures as newborns not uncommonly develop autism, and studies indicate that about 40 percent of patients with autism also have epilepsy. New research at Boston Children’s Hospital finds a reason for the link, and suggests a way to break it — using an existing drug that’s already been given safely to children.
In the online journal PLoS ONE, Frances Jensen, MD, in the Department of Neurology and the F.M. Kirby Neurobiology Center at Boston Children’s, and lab members Delia Talos, PhD, Hongyu Sun, MD, PhD, and Xiangping Zhou, MD, PhD, showed in a rat model that early-life seizures not only lead to epilepsy later in life, but also produce autistic-like behaviors.
Drilling deeper, they showed that early seizures hyper-activate a group of signaling molecules collectively known as the mTOR pathway. This increased signaling – above and beyond the normal surge that happens early in life – disrupts the normal balance of connections (synapses) in the rats’ developing brains. The rats go on to develop epilepsy and altered social behavior, and Jensen believes something parallel happens in humans.
But here’s what’s exciting. They did other experiments where they gave the rats the drug rapamycin, which disables the mTOR pathway, before and after seizures. The mice did not show abnormal synapse or circuit development, and were less likely to have seizures later in life. Autistic-like symptoms appeared less often.