Ethanol pretreatment enhances NMDA excitotoxicity in biogenic amine neurons: Protection by brain derived neurotrophic factor

Background: Biogenic amine neurons are involved in a number of mental disea ses including addiction and alcohol dependence. Because chronic ethanol is known to cause supersensitivity to NMDA excitotoxicity in cortical neurons, this study sought to determine the effect of ethanol treatment on biogenic amine neurons. Methods: To determine if ethanol exposure alters the vitality of biogenic a mine neurons; cultures were prepared from E14 rat brain. After 24 hr in cul ture, cells were divided into control or ethanol (100 mM) treatment groups, cultured an additional 48 hr, and then half of them exposed to NMDA for 25 min. The NMDA was then removed and cells cultured in fresh media for an ad ditional 24 hr to allow for excitotoxic delayed neuronal death. Cultures we re then stained with antibodies to 5-hydroxytryptamine or tyrosine hydroxyl ase to identify serotonin and dopamine neurons, respectively. Cultures were analyzed for cell number and neuronal morphology. Results: Ethanol treatment alone had no effect on biogenic amine cell numbe r, soma area, number of neurites, or terminal segments, although the field area of dopamine neurons was decreased. Treatment with 30 mu M NMDA had no effect on controls, but significantly decreased dopamine neurons in ethanol -treated cultures as well as reduced soma area, field area, number of neuri tes and number of terminal segments. Treatment with higher concentrations o f NMDA reduced dopamine and serotonin neurons in both controls and ethanol- treated groups, and ethanol treatment significantly enhanced NMDA excitotox ic effects. Treatment with Brain Derived Neurotrophic Factor (BDNF) prevent ed ethanol sensitization to NMDA excitotoxicity. Conclusions: These studies suggest that ethanol treatment sensitizes biogen ic amine neurons to excitotoxic insults. Ethanol sensitization of biogenic amine neurons to insults could contribute to the development of mental dise ase.