ACUTE INTERACTION BETWEEN ETHANOL AND SEROTONIN METABOLISM IN THE RAT

The effect of acute ethanol an peripheral serotonin (5HT) metabolism w as studied in Sprague-Dawley rats. Four hours after a single dose of e thanol (1.0 g/kg) administered into the stomach, a significant increas e in the 5HT level in stomach tissue and a decrease in ileum was obser ved. The level of 5-hydroxyindole-3-acetic acid (5HIAA) was increased in urine, while increased concentrations of 5-hydroxytryptophol (5HTOL ) occurred in jejunum, ileum, spleen and urine. After 7-9 h when the b rood ethanol concentration had returned to zero, SHTOL levels were sti ll higher than control values in jejunum, ileum and urine. At 4 h, an elevated ratio of 5HTOL to 5HIAA Nas observed in urine and ileum (by s imilar to 2-fold), liver (similar to 3-fold), and spleen (similar to 5 -fold), whereas the ratio was reduced in stomach. In urine and spleen, this metabolic shift persisted after 7-9 h. The SHTOL level in bile w as increased by similar to 3.5-fold after 8 h. 5HIAA was not detectabl e in bile. The present results indicate that the rat has a much higher proportion of SHTOL formation than man under normal conditions. The r at does not appear to be an ideal model for studying the interaction b etween ethanol and 5HT metabolism in man.