THE EFFECT OF PHOSPHOLIPASES ON THE ACTIVE UPTAKE OF NOREPINEPHRINE BY SYNAPTOSOMES ISOLATED FROM THE CEREBRAL CORTEX OF GUINEA PIG¹

Abstract

Phospholipase A (EC 3.1.1.4) and phospholipase C (EC 3.1.4.3) were used for studying the role of phospholipid of synaptosomal membrane on norepinephrine uptake activity. Synaptosomes were isolated from cerebral cortex of guinea pigs and treated with phospholipase A or phospholipase C before the uptake experiments. Treatment of synaptosomes with phospholipase A has resulted in severe inhibition of norepinephrine-uptake. Under similar conditions, the activity of synaptosomal (Na + K)-

The biochemical mechanisms of the excitotoxicity of Kainic acid

“…Crude synaptsomes from both control and KA-treated gerbils were used for (Na +, K+)-ATPase assay (Sun, 1974).…”

THE EFFECTS OF AGE AND ALCOHOL ON (Na++ K+)‐ATPASE ACTIVITY OF WHOLE HOMOGENATE AND SYNAPTOSOMES PREPARED FROM MOUSE AND HUMAN BRAIN

“…Many structures such as cell membranes may be present for long periods and undergo progressive and irreversible changes with age (KOHN, 1971). Synaptoso-ma1 membranes may be particularly susceptible to oxidative changes because of their high content of polyunsaturated fatty acids (SUN & SUN, 1972). Studies on subcellular fractions of developing brain showed an increasing trend in lipid peroxidation with the advancing age of the animal (BISHAYEE & BALASUBRAMANIAN, 1971).…”

“…Studies on subcellular fractions of developing brain showed an increasing trend in lipid peroxidation with the advancing age of the animal (BISHAYEE & BALASUBRAMANIAN, 1971). We have recently shown that lipid peroxidation inhibits membrane-bound synaptosomal (Na' + KC)-ATPase activity (SUN, 1972). Since both ethanol and lipid peroxidation may effect synaptosomal ATPase activity in the brain, it is possible that there may be a significant interaction between these 2 variables which may account for some of the differences in sensitivity to alcohol and other agents in relation to age.…”

Aging and in vivo norepinephrine-uptake in mammalian brain

“…The active transport of catecholamines depends very much on the structural integrity of synaptosomal membrane (Sun, 1974;Sun & Sun, 1976). Due to the presence of highly unsaturated fatty acids in the synaptosomal membrane (Sun & Sun, 1972) brane structure may be considered as an important aging factor resulting in the formation of age pigment and declining of some membrane dependent enzymic activity (Sun & Samorajski, 1975).…”

“…The decrease in catecholamine concentration in brain regions may reflect a decline in enzymic activity for catecholamine synthesis with age or an increase in degradative enzymic activity. Some investigators have demonstrated that brain tyrosine hydroxylase (TH) decreases with age (McGeer & McGeer, 1975;Cote & Kremzner, 1974 , 1974;Cote & Kremzner, 1974). This decreased capacity to synthesize catecholamines, coupled with increasing M A 0 activity could explain the declining motor and mental activities of the aged patients.…”