The effect of polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (22:6n-3; DHA) and arachidonic acid (20:4n-6; AA), on apoptotic cell death was evaluated based on DNA fragmentation and caspase-3 activity induced by serum starvation using Neuro-2A and PC-12 cells. The presence of 20:4n-6 in the medium during serum starvation decreased DNA fragmentation and this initial protective effect was diminished with prolonged serum starvation. The observed protective effect of 20:4n-6 was not affected by the inhibitors of cyclooxygenase (COX) and lipoxygenase. Conversely, 22:6n-3 became protective only after the enrichment of cells with this fatty acid at least for 24 h prior to the serum deprivation. DNA fragmentation as well as caspase-3 activity was reduced in 22:6n-3 enriched cells with a concomitant decrease in protein and mRNA levels. During the enrichment period, 22:6n-3 steadily increased its incorporation into PS leading to a significant increase in the total PS content; the protective effect of 22:6n-3 paralleled the PS accumulation. Neither direct exposure of cells to nor enrichment with 18:1n-9 had any protective effect. In conclusion, it is proposed that 20:4n-6 prevents neuronal apoptosis primarily due to the action of nonesterified 20:4n-6 but 22:6n-3, at least in part, through PS accumulation.

We studied the effects of chronic ethanol exposure on the mobilization of polyunsaturated fatty acids stimulated by activation of the type 2A serotonin receptor in C6 glioma cells. In our in vitro model, we prelabeled cells with [3H]arachidonate and [14C]docosahexaenonate and subsequently stimulated with the type 2A serotonin receptor agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride. In as early as 10 days of exposure to 20 or 50 mM ethanol, the (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride-simulated mobilization of [3H]arachidonic acid [[3H]AA) and [14C]docosahexaenoic acid ([14C]DHA) was significantly inhibited, and this inhibition was accompanied by decreased mobilization of intracellular [Ca2+]i. Exposure to ethanol did not alter significantly the release of [3H]AA and [14C]DHA stimulated by the calcium ionophore A23187 nor the incorporation of [3H]AA and [14C]DHA into cellular lipids. Decreased mobilization of polyunsaturated fatty acids and calcium in astroglia may contribute to neurotoxicity caused by chronic ethanol exposure.

We studied the effects of chronic ethanol exposure on the mobilization of polyunsaturated fatty acids stimulated by activation of the type 2A serotonin receptor in C6 glioma cells. In our in vitro model, we prelabeled cells with [3H]arachidonate and [14C]docosahexaenonate and subsequently stimulated with the type 2A serotonin receptor agonist (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride. In as early as 10 days of exposure to 20 or 50 mM ethanol, the (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride-simulated mobilization of [3H]arachidonic acid [[3H]AA) and [14C]docosahexaenoic acid ([14C]DHA) was significantly inhibited, and this inhibition was accompanied by decreased mobilization of intracellular [Ca2+]i. Exposure to ethanol did not alter significantly the release of [3H]AA and [14C]DHA stimulated by the calcium ionophore A23187 nor the incorporation of [3H]AA and [14C]DHA into cellular lipids. Decreased mobilization of polyunsaturated fatty acids and calcium in astroglia may contribute to neurotoxicity caused by chronic ethanol exposure.