Nutritional and Microbial Effects on Liver Monoamine Oxidase and Serotonin in the Chick

Abstract
The total liver monoamine oxidase in germfree chicks was significantly higher than in conventional (contaminated) animals. Chicks monocontaminated with a Bacillus sp., manifested a liver enzyme value that was intermediate between the two above groups of animals. The concentrations of liver serotonin were similar in germfree and conventional chicks. A pyridoxine deficiency in conventional birds reduced liver serotonin, and elevated liver monoamine oxidase activity. Possible explanations of these results were discussed.