Improved posthypoxic recovery of synaptic transmission in gerbil neocortical slices treated with a calpain inhibitor.

BACKGROUND AND PURPOSE

Among the various calcium-induced biologic events occurring in hypoxic neurons, activation of the calcium-activated neutral proteinase (calpain) is a likely mediator of neuronal degeneration. In this study, we assessed the protective effects of a calpain inhibitor (Cbz-Val-Phe-H) against hypoxic damage to the neocortex.

METHODS

An in vitro neocortical slice model from gerbils was used to study the delay to hypoxic depolarization during hypoxia and the recovery of synaptic responses after hypoxia. These responses were examined in control slices and slices treated with Cbz-Val-Phe-H.

RESULTS

The delay to hypoxic depolarization did not differ between treated and control groups. In contrast, synaptic recovery after a fixed period of hypoxia (15 minutes) was significantly improved in the Cbz-Val-Phe-H-treated slices (P < .01). Concentrations of Cbz-Val-Phe-H of 50 mumol/L or greater were significantly more protective than a concentration of 20 mumol/L (P < .01).

CONCLUSIONS

The data indicate that calcium-activated proteolysis plays a critical role in hypoxic damage to the neocortex and that calpain inhibitors may be useful therapeutic agents.