Attenuation of somatodendritic responses to 8-hydroxy-2-di-npropylamino tetralin following long-term dietary sugar consumption in rats.

OBJECTIVE

To determine changes in response to a selective serotonin-1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) following long-term consumption of sugar as part of meal in rats.

STUDY DESIGN

Experimental study.

PLACE AND DURATION OF STUDY

The Department of Biochemistry, University of Karachi, from June to August 2005.

METHODOLOGY

The study was conducted on 24 male albino Wistar rats. Sugar containing diet was prepared by mixing standard rodent diet and table sugar in the ratio of 3:1 (w/w) and rats were fed freely on this diet. Control rats were fed freely on standard rodent diet. After five weeks of treatment, control and sugar diet treated animals were injected with 8-OH-DPAT, at a dose of 0.5 mg/ml/kg, to monitor the effects of drug on food intake and brain serotonin (5-hydroxytryptamine, 5-HT) metabolism. Dissected neural tissue was analyzed electrochemically and findings were compared by Newman-Keuls test.

RESULTS

Administration of 8-OH-DPAT elicited hyperphagia and decreased 5-HT metabolism in normal diet treated rats. The neurochemical and hyperphagic responses to 8-OH-DPAT were smaller in sugar than normal diet treated animals suggesting a downregulation of somatodendritic responses in sugar diet treated animals.

CONCLUSION

A decrease in serotonin metabolism but not an increase in the responsiveness of somatodendritic 5-HT-1A receptors is involved in sugar-rich diet induced hyperphagia.