been shown to mimic psychosis but chronic administration in laboratory animals resulted in similar neuropathological changes as in schizophrenia. Possible future medical uses The effects of dizocilpine at NMDA receptors are clear and significant. NMDA receptors are key in the progression of excitotoxicity (a process in which an excessive amount of extracellular glutamate overexcites glutamate receptors and harms neurons). Thus NMDA receptor antagonists including dizocilpine have been extensively studied for use in treatment of diseases with excitotoxic components, such as stroke, traumatic brain injury, and neurodegenerative diseases such as Huntington's, Alzheimer's, and amyotrophic lateral sclerosis. Dizocilpine has shown effectiveness in protecting neurons in cell culture and animal models of excitotoxic neurodegeneration. The administration of dizocilpine protected the hippocampus from ischemia-induced neurodegeneration in the gerbil. The ED50 (effective dose 50) for neuroprotection was 0.3 mg/kg and the majority of the animals were protected against the ischemia-induced damage at doses greater than or equal to 3 mg/kg, when dizocilpine was given one hour prior to the occlusion of the carotid arteries, although other studies have shown protection up to 24 hours post-insult. Excitatory amino acids, such as glutamate and aspartate, are released in toxic amounts when the brain is deprived of blood and oxygen and NMDA antagonists are thought to prevent the neurodegeneration through the inhibition of these receptors. Behavioural studies have shown that NMDA receptors are involved in the development of psychological dependence caused by chronic administration of morphine. Dizocilpine suppressed the morphine-induced rewarding effect. It is suggested that stimulating NR2B subunits of the NMDA receptor and its associated kinases in the nucleus accumbens leads to the rewarding effect caused by morphine. Inhibition of this receptor and its kinases in the nucleus accumbens by co-treatment with NMDA antagonists prevents morphine-associated psychological dependence. An earlier study has shown that the prevention of morphine-associated psychological dependence was not due to state-dependency effects induced by dizocilpine but rather reflect the impairment of learning that is caused by NMDA antagonists. This is consistent with studies showing that dizocilpine potentiates the addictive potential of morphine and other drugs (see below). As an antidepressant, positive results were found in animal models of depression. NMDA antagonists like dizocilpine have been shown in animal models to attenuate the hearing loss caused by aminoglycosides It is thought that aminoglycosides mimic endogenous polyamines at NMDA receptors and produce excitotoxic damage, leading to hair cell loss. Antagonizing NMDA receptors to reduce the