Effect of intraventricular adenosine on food intake in rats

Previous studies have shown that peripherally administered purines suppress food intake in rats. In this study we show that central administration of adenosine, adenine and AMP potently suppressed food intake in rats. Intraperitoneal adenosine suppressed feeding at the 100 and 50 mg/kg dose whereas 100, 50 and 10 μg of intraventricular adenosine suppressed feeding after intracerebroventricular injection at 30 minutes and up to 120 minutes at the high doses. Inosine, 2-deoxyinosine, 7-methyl-inosine and 2-deoxyguanosine all failed to suppress food intake when given intraventricularly at the same doses used for adenosine, adenine and AMP. Adenosine, 10 μg ICV, also decreases water uptake. The effect of adenosine was specific for ingestive behaviors as it did not significantly decrease spontaneous movement or grooming. These results suggest that adenosine suppresses feeding via a central mechanism and that this suppressive effect is not dependent on deamination of adenosine to inosine. The central adenosine effect appears to work by a different mechanism to the satiety effect of peripherally administered inosine.