Arachidonic acid enhances intracellular calcium levels in dentate gyrus, but not CA1, in aged rat

The effect of dietary supplementation with polyunsaturated fatty acids (PUFAs) on long-term potentiation (LTP) and calcium mobilization in hippocampal slices from aged rats was assessed. LTP magnitude was significantly greater in PUFA-supplemented animals compared to age-matched controls (OCs). LTP did not differ among PUFA-supplemented groups. Calcium mobilization was estimated following membrane depolarization and selective activation of NMDA receptors. The resting level of [Ca2+]i was slightly elevated in aged preparations compared to young controls (YCs). The transient increase in [Ca2+]i in CA1 was significantly smaller in aged rats than in YC. The maximum increase in [Ca2+]i in the CA1 and dentate gyrus (DG) did not differ among aged groups. The maximum increase in [Ca2+]i and the calcium buffering ability were significantly greater in YC than in the aged rats. Selective activation of NMDA receptors induced regional differences in Ca2+ elevation. In the DG, Ca2+ elevation in OA was comparable to that in YC, and significantly higher than that in OC, suggesting that long-term arachidonic acid supplementation rescues the reduced neurogenesis in the DG. The decay in the depolarization and NMDA-induced increase in [Ca2+]i was prolonged in aged CA1 and DG.