SUMMARYDespite a prevalence exceeding 1%, mechanisms underlying autism spectrum disorders (ASDs) are poorly understood, and targeted therapies and guiding parameters are urgently needed. We recently demonstrated that cerebellar dysfunction is sufficient to generate autistic-like behaviors in a mouse model of tuberous sclerosis complex (TSC). Here, using the mechanistic target of rapamycin (mTOR)-specific inhibitor rapamycin, we define distinct sensitive periods for treatment of autistic-like behaviors with sensitive periods extending into adulthood for social behaviors. We identify cellular and electro-physiological parameters that may contribute to behavioral rescue, with rescue of Purkinje cell survival and excitability corresponding to social behavioral rescue. In addition, using anatomic and diffusion-based MRI, we identify structural changes in cerebellar domains implicated in ASD that correlate with sensitive periods of specific autism-like behaviors. These findings thus not only define treatment parameters into adulthood, but also support a mechanistic basis for the targeted rescue of autism-related behaviors.

Drugs targeting metabotropic glutamate receptor 5 (mGluR5) have therapeutic potential in autism spectrum disorders (ASD), including tuberous sclerosis complex (TSC). The question whether inhibition or potentiation of mGluR5 could be beneficial depends, among other factors, on the specific indication. To facilitate the development of mGluR5 treatment strategies, we tested the therapeutic utility of mGluR5 negative and positive allosteric modulators (an mGluR5 NAM and PAM) for TSC, using a mutant mouse model with neuronal loss of Tsc2 that demonstrates disease-related phenotypes, including behavioral symptoms of ASD and epilepsy. This model uniquely enables the in vivo characterization and rescue of the electrographic seizures associated with TSC. We demonstrate that inhibition of mGluR5 corrects hyperactivity, seizures, and elevated de novo synaptic protein synthesis. Conversely, positive allosteric modulation of mGluR5 results in the exacerbation of hyperactivity and epileptic phenotypes. The data suggest a meaningful therapeutic potential for mGluR5 NAMs in TSC, which warrants clinical exploration and the continued development of mGluR5 therapies.

Hypertension (HTN) disrupts vital neurovascular control mechanisms, thereby increasing the brain’s susceptibility to vascular insufficiency, white matter lesions, and cognitive impairment. Yet, the distinct vascular, neuronal, and glial cell types targeted by HTN, as well as the ensuing cellular network disruption driving the neurovascular and cognitive deficits remain undefined. Here we sought to uncover transcriptomic changes in neurons and vascular cells using unbiased, single-cell RNA sequencing on the neocortex of 10-week old C57BL/6 male mice with angiotensin II (AngII) HTN. Vehicle or AngII (600ng/kg/min s.c.) were administered for 3 days, when blood-brain barrier (BBB) permeability start to increase, or 42 days, when neurovascular and cognitive dysfunction are fully developed (n=3/group). We analyzed 39,451 single-cell transcriptomes comprising 26 cell types. Surprisingly, 3 days of AngII induced significantly greater transcriptional changes in venular ECs compared to arteriolar ECs (EdgeR; pval< 0.05, logFC> 2), supporting the notion that venular ECs are uniquely sensitive to the early effects of HTN (Hypertension 76:795, 2020). Gene ontology analysis of differentially expressed genes prominently implicated altered venular immune signaling, BBB dysfunction, and, notably, a secretory phenotype characteristic of senescence (pval <0.05). Moreover, unbiased ligand-receptor interaction analysis (CellChat) demonstrated that senescent venular ECs strongly communicate with oligodendrocyte precursors, and NPY-expressing interneurons, pointing to a previously unrecognized early disruption in the oligo-vascular niche, essential for maintaining white matter integrity, and neuronal network stability. Furthermore, at 42 days of AngII we observed an overrepresentation of aging and neurodegeneration-linked genes in oligos and NPY interneurons, relating to myelin disruption, synaptic dysfunction, and metabolic dysregulation. The data reveal a novel endothelial-oligo-interneuron crosstalk and transcriptomic alterations underlying the impact of HTN on the brain. Future studies will establish how these transcriptomic changes are linked to neurovascular dysfunction, white matter damage and cognitive impairment.