Neuropharmacology adenosine A2A receptor and glial glutamate transporter GLT-1 are synergistic targets to reduce brain hyperexcitability after traumatic brain injury in mice

Abstract

Traumatic brain injury (TBI) is a leading cause of acquired epilepsy, with post-traumatic epilepsy (PTE) significantly contributing to morbidity and mortality. To date, there is no treatment capable to prevent the development of PTE, which remains an urgent unmet need. Previous studies suggest that adenosine A_2A receptor (A_2AR) activation and glutamate transporter 1 (GLT-1) dysregulation may contribute to epileptogenesis, however, it is unclear whether therapeutic targeting of the A_2AR or GLT-1 can attenuate TBI-induced hyperexcitability, and whether there are synergistic interactions between the two. Here, we investigated the therapeutic potential of two FDA approved drugs istradefylline (A_2AR inhibitor) and ceftriaxone (GLT-1 activator) in preventing long-lasting brain hyperexcitability in a clinically relevant rodent model of TBI. Adult male mice underwent controlled cortical impact (CCI)-induced TBI and were randomly assigned to istradefylline, ceftriaxone, istradefylline/ceftriaxone, or vehicle groups, receiving treatment during the first 24 h post-injury. Susceptibility to chemoconvulsant-evoked seizures was quantified at 4–5 weeks after CCI. We show that CCI caused a reduction in GLT-1 and an increase in A_2AR protein levels in the ipsilateral hippocampus. Transient acute treatment with istradefylline or ceftriaxone reduced brain hyperexcitability at 4–5 weeks post-TBI. Notably, mice treated with the combination of istradefylline and ceftriaxone exhibited increased GLT-1 levels, accompanied by further reductions in brain hyperexcitability, showing greater effects than either drug alone. Our findings identify a novel disease-modifying approach following TBI using a combination of two FDA-approved drugs which might be useful to mitigate the long-lasting brain hyperexcitability-induced by TBI.