Long-term consumption of sugar-rich diet decreases the effectiveness of somatodendritic serotonin-1A receptors

Abstract

8-Hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT), a 5-hydroxytryptamine (5-HT)-1A selective agonist was used to investigate a possible role of somatodendritic serotonin-1A receptors in the precipitation of hyperphagia and decreases of 5-HT metabolism associated with long-term consumption of sugar rich-diet. In the first part of study, dose-related hyperphagic effects of 8-OH-DPAT were monitored in freely feeding rats. In the second part of study, rats were fed freely on a sugar-rich diet (prepared by mixing standard rodent diet with table sugar in the ratio of 3:1 [w/w]) for 5 weeks. Hyperphagic effects of 8-OH-DPAT were monitored in sugar-rich diet and normal diet treated rats by injecting the drug at a dose of 0.25 mg/kg body weight, a dose that produced significant hyperphagia. Effects of 8-OH-DPAT on decreasing 5-HT metabolism in the hypothalamus were also investigated in the two groups. Results showed that administration of 8-OH-DPAT at a dose of 0.25 mg/kg body weight elicited hyperphagia and decreased 5-HT metabolism in normal diet treated animals but the effects in sugar-rich diet treated animals were smaller and not significant suggesting a decrease in the effectiveness of somatodendritic 5-HT-1A receptors, which provide a feedback control over the synthesis and release of 5-HT in terminal region. A possible mechanism involved in sugar-diet induced decreases of 5-HT metabolism is discussed.

Association between sugar-sweetened beverage consumption and depression and suicidal ideation among Korean adults: a cross-sectional study from the 2014 and 2016 Korean National Health and Nutrition Examination Survey (KNHANES)

“…Third, a study in the Netherlands showed that men who followed a high-fat, high-sugar diet for 6 weeks showed a significant decrease in level of serotonin transporter-binding in the hypothalamic region, that is, by 30%, in single photon emission computed tomography scans [ 28 ]. This decrease in serotonin level may increase the possibility of the development of anxiety and depression [ 29 ]. Fourth, the intake of sugar causes neurobiological changes in the reward system, compelling the individual to consume more sugar; it can affect negative emotional symptoms, similar to other substance-related addictive disorders [ 30 31 ].…”

Daily intake of soft drinks is associated with symptoms of anxiety and depression in Chinese adolescents

“…In mechanistic studies with murine models, researchers showed that long-term diet rich in sugar is associated with decreased effectiveness of somatodendritic serotonin-1A receptors, which provide feedback control over the synthesis and release of serotonin (mood regulator) in the hypothalamus (32) . Hypothalamus serotonin plays an essential role in the occurrence of mental illness.…”

Consumption of palatable food decreases the anorectic effects of serotonergic, but not dopaminergic drugs in baboons

“…An early study [12] failed to see an effect of a high sucrose diet on the anorectic effects of the serotonin releaser dexfenfluramine in rats. Another research group, however, has observed an attenuated behavioral response, e.g., paw treading, of the direct serotonin 1-A receptor agonist 8-hydroxy-N.N-dipropyl-2-aminotetralin (8-OH-DPAT) following consumption of a diet high in sucrose in rats [13, 14], hypothesized to be related to serotonin receptor desensitization [15, 16]. …”