Abstract
Rats were fed either linoleate-rich safflower oil or α-linolenate-rich perilla oil diets. The brightness-discrimination learning performance was significantly higher in the perilla oil group than in the safflower oil group. In synapses of hippocampus CA1, the density of synaptic vesicles was significantly higher in the perilla oil-fed rats than the safflower oil-fed rats. The number of terminals with low density of synaptic vesicles was increased in the safflower oil group after the learning. Fourier transform infrared spectroscopy of rat brain microsomes revealed that the second derivative spectrum at 1050-1250 cm-1showed difference between perilla and safflower oil groups after the learning. The infrared band at 1727 cm-1 in the safflower oil group moved to the higher wavenumber position at 1731 cm-1in the perilla oil group after the learning. The results suggested that the hydrogen bond of fatty acid ester (sn-2) with water was weakened and moved inward of the membrane, and resulted in a lowered hydration. This was confirmed by the weakened reactivity of the membrane phospholipids to phospholipase A2 in the perilla oil group after the learning. These results suggested that n-3 polyunsaturated fatty acid-deficiency may affect the turnover of synaptic vesicles in hippocampus with loss of learning ability.
