Betaine Attenuates Glutamate-induced Neurotoxicity in Primary Cultured Brain Cells

Effects of betaine on glutamate-induced neurotoxicity were examined on primary culturs 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 .mu.M glutamate produced wide-spread acute neuronal swelling and neurtic fragmentation. A 2-h pretreatment of cultured chicken embryonic brain cells with i mM betaine prior to a 30 min exposure to 500 , mu, M glutamate significantly raised the survival rate of neurons in the culture. When chicken embryonic brain cells were pretreated for 2 h with i mM betaine followed by exposure to 100 .mu.M glutamate for 42 h, lactate dehydrogenase levels within the cells remained at 62% of .mu.M untreated control values while glutamate-treated control fell to 0% lactate dehydrogenase. Betaine also exerted attenuating effects on N-methyl-D-asparte-, kainate-and quisqualate-induced neurotoxicity in a similar manner to that observed with glutamate. Similar neuroprotective effects of betaine with rat cortical cultures.