Effects of ethanol consumption and intake of low-carbohydrate (low-CHO) diet on noradrenalin (NA), dopamin (DA) and its metabolite, 3, 4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), serotonin (5HT) and its metabolite, 5-hydroxyindoleacetic acid (5HIAA) contents in six brain regions of rats were investigated.
1) Change of DA neuron
Ethanol-containg control diet (hypercaloric ethanol diet) did not affect DA content in any area of brain, but decreased HVA in cortex and hypothalamus and increased DOPAC and HVA in midbrain. Low-CHO diet increased DA content in striatum, DOPAC and HVA in midbrain, but decreased DOPAC in hippocampus and hypothalamus, and HVA in cortex, pons and medulla, hippocampus and hypothalamus. Ethanol-containing low-CHO diet (isocaloric ethanol diet) increased DA level in striatum, DOPAC and HVA in midbrain, but decreased HVA in cortex, hippocampus, striatum and hypothalamus. These results suggest that i) hypercaloric ethanol diet has an opposite effect to carbohydrate on DA metabolism: hypercaloric ethanol diet and lowered carbohydrate intake
per se enhance DA metabolism in midbrain, whereas inhibit it in cortex and hypothalamus, ii) lowered carbohydrate intake also declines DA metabolism in pons and medulla and hippocampus, whereas enhances DA synthesis in striatum, iii) the combined effect of ethanol and carbohydrate intake on DA metabolism is inhibited each other in the rats of isocaloric ethanol diet feeding, and this diet decreased DA metabolism in striatum.
2) Change of 5HT neuron
Hypercaloric ethanol diet did not affect the contents of 5HT and 5HIAA in any region of brain. Low-CHO diet increased 5HIAA in pons and medulla, striatum and hypothalamus, but decreased it in hippocampus. Isocaloric ethanol diet decreased 5HT content in hypothalamus and 5HIAA in hippocampus. These results suggest that i) low-CHO diet enhances 5HT metabolism in pons and medulla, striatum and hypothalamus, but declines it in hippocampus, ii) isocaloric ethanol diet diminishes the effect of low-CHO diet on 5HT metabolism in pons and medulla, and striatum and inhibits 5HT synthesis in hypothalamus.
3) Change of NA neuron
Hypercaloric ethanol diet did not influence the level of NA in any region of brain as in the case of DA and 5HT neuron. Low-CHO diet and isocaloric ethanol diet increased NA content in striatum to the same degree. Isocaloric ethanol decreased NA level in cortex and hippocampus.
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