Abstract
Histamine is a major neurotransmitter and alleviates neuronal damage after ischemic injury via H2 receptors. Herein, we investigated the effects of H2 receptor agonists on the blood-brain barrier (BBB) disruption after traumatic brain injury (TBI). Male ddY mice were used to generate the TBI model, in which a fluid percussion injury (FPI) was induced by a hydraulic impact. The BBB disruption was evaluated using Evans blue extravasation. H2 receptor agonists, amthamine and dimaprit, were administered into the lateral cerebroventricle (i.c.v.) or tail vein (i.v.) from 3 hours to 3 days after FPI. The i.c.v. or i.v. administration of amthamine and dimaprit reduced FPI-induced Evans blue extravasation and promoted mRNA expression of vascular protective factors, including angiopoietin-1 and sonic hedgehog. The co-administration of ranitidine, a H2 receptor antagonist, inhibited these effects. Expression of the H2 receptor was observed in astrocytes and brain microvascular endothelial cells (BMECs) in the injured cortex. Treatment with amthamine and dimaprit promoted mRNA expression of vascular protective factors in astrocytes and BMECs. These results suggest that H2 receptor agonists alleviate TBI-induced BBB disruption by increasing the expression of vascular protective factors in astrocytes and BMECs.