[H2 receptor mediates the protective effect of histamine against the cellular edema and viability reduction induced by oxygen-glucose deprivation in rat hippocampal slices].

OBJECTIVE

To determine the effect of histamine on ischemia-induced cellular edema and viability reduction in rat hippocampal slices, and the involved subtypes of histamine receptor in this effect.

METHODS

In vitro ischemic injury of hippocampal slices was induced by oxygen-glucose deprivation (OGD). The slice injury was determined by real-timely measuring the changes of light transmittance (LT) for the cellular edema in CA1 region of the hippocampal slice, and by detecting the product of 2, 3, 5-triphenyltetrazolium chloride (TTC), formazan, for the slice viability. The effect of histamine at various concentrations on the slice injury was observed, and the blockage by antagonists of histamine receptors was also investigated.

RESULTS

Histamine (0.01-10 micromol x L(-1)) inhibited the peak value of LT during OGD in hippocampal slices and improved the reduced viability after OGD. Diphenhydramine (0.1-10 micromol x L(-1)), an H1 receptor antagonist, did not affect the effect of histamine, while cimetidine (0.1-10 micromol x L(-1)), an H2 receptor antagonist, partly abolished the protective effect of histamine.

CONCLUSIONS

Histamine protects hippocampal slices against ischemia-induced cellular edema and viability reduction; this effect might be mediated via, at least partly, H2 receptor.