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Abstract

A method is disclosed for reducing excitotoxic damage to neurons, which can occur as a result of stroke, cardiac arrest, or other events or conditions. This method involves administering an aminoglycoside that suppresses the flow of calcium ions into neurons through N-type calcium channels. To be effective for such use, an aminoglycoside must suppress N-channel activity at a potency greater than streptomycin. Aminoglycosides which meet this criterion (which includes neomycin and Gentamicin) can suppress the depolarizing activation of neurons, which in turn controls the release of glutamate, a neurotransmitter that becomes an endogenous toxin under excitotoxic conditions. Numerous aminoglycosides were tested in in vitro screening tests using brain cell membrane fragments to evaluate N-channel blocking potency. Aminoglycosides with the highest N-channel blocking potency were then tested using (1) in vitro tests on hippocampal brain tissue, to evaluate recovery of neuronal activity after a period of oxygen deprivation; (2) in vivo tests to evaluate the control of induced seizures in intact adult mammals; and (3) in vivo tests to evaluate the reduction of brain damage due to surgically-induced ischemia in intact adult mammals. The results showed that (1) aminoglycosides which are more potent than streptomycin in blocking N-channel ion flow are effective in reducing excitotoxic brain damage, without causing undesired side effects, and (2) the effectiveness of all BBB-permeable aminoglycosides tested to date in preventing excitotoxic brain damage is directly correlated with their potency in suppressing N-channel activity. Evaluation of chemical structures also indicates a correlation between the number of primary amino groups on an aminoglycoside, and its potency as an N-channel blocker and neuroprotective agent.

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