Betaine attenuates glutamate-induced neurotoxicity in primary cultured brain cells

Effects of betaine on glutamate-induced neurotoxicity were examined on primary cultures of chicken embryonic brain cells and on rat cortical cultures. Betaine was found to attenuate glutamate-induced neurotoxicity both morphologically and biochemically. A 30 min exposure of chicken embryonic brain cells cultured for 12 days to 500 μM glutamate produced wide-spread acute neuronal swelling and neuritic fragmentation. A 2-h pretreatment of cultured chicken embryonic brain cells with 1 mM betaine prior to a 30 min exposure to 500 μM glutamate significantly raised the survival rate of neurons in the culture. When chicken embryonic brain cells were pretreated for 2 h with 1 mM betaine followed by exposure to 100 μM glutamate for 42 h, lactate dehydrogenase levels within the cells remained at 63% of untreated control values while glutamate-treated controls fell to 0% lactate dehydrogenase. Betaine also exerted attenuating effects on N-methyl-D-aspartate-, kainate- and quisqualate-induced neurotoxicity in a similar manner to that observed with glutamate. Similar neuroprotective effects of betaine were obtained with rat cortical cultures.