Moclobemide attenuates anoxia and glutamate-induced neuronal damage in vitro independently of interaction with glutamate receptor subtypes

Abstract

Recent data suggested the existence of a bidirectional relation between depression and neurodegenerative diseases resulting from cerebral ischemia injury. Glutamate, a major excitatory neurotransmitter, has long been recognised to play a key role in the pathophysiology of anoxia or ischemia, due to its excessive accumulation in the extracellular space and the subsequent activation of its receptors. A characteristic response to glutamate is the increase in cytosolic Na + and Ca 2+ levels which is due mainly to influx from the extracellular space, with a consequent cell swelling and oxidative metabolism dysfunction. The present study examined the in vitro effects of the antidepressant and type-A monoamine oxidase inhibitor, moclobemide, in neuronal–astroglial cultures from rat cerebral cortex exposed to anoxia (for 5 and 7 h) or to glutamate (2 mM for 6 h), two in vitro models of brain ischemia. In addition, the affinity of moclobemide for the different glutamate receptor subtypes and an interaction with the cell influx of Na + and of Ca 2+ enhanced by veratridine and K + excess, respectively, were evaluated. Moclobemide (10–100 μM) included in the culture medium during anoxia or with glutamate significantly increased in a concentration-dependent manner the amount of surviving neurons compared to controls. Moclobemide displayed no binding affinity for the different glutamate receptor subtypes (IC 50 > 100 μM) and did not block up to 300 μM the entry of Na + and of Ca 2+ activated by veratridine and K +, respectively. These results suggest that the neuroprotective properties of moclobemide imply neither the glutamate neurotransmission nor the Na + and Ca 2+ channels.