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School of Public Health, University of California, Los Angeles, CA 90024
The purpose of this study was to investigate the dietary regulation of the two key enzymes in polyamine biosynthesis, ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) in rat tissues. Either an amino acid mix (patterned after casein), a complete diet or several dietary components were administered to fasting rats by gastric tube. Rats were killed at specific time intervals, over a 12-hour period, and the activities of ODC and SAMDC were measured in the following tissues: liver, kidney, small intestine, brain and skeletal muscle. The amino acid mix, as well as the complete diet, elicited rapid and substantial increases in ODC and SAMDC activities in liver, kidney and intestine. In brain and muscle SAMDC activity only was increased. Studies with actinomycin D showed that SAMDC and ODC activities are regulated at transcription. The mechanism eliciting the observed increases in enzyme activities is postulated to be the influx of amino acids into cells rather than the influence of hormones secreted in response to dietary stimulation.
KEY WORDS: polyamines ornithine decarboxylase Sadenosylmethionine decarboxylase
1 Supported by National Institutes of Health grant AM15197.
2 Preliminary results of some of this work have been presented: Auvenshine, P., Shibata, S. & Swendseid, M. E. (1981) The dietary regulation of S-adenosylmethionine decarboxylase, Fed. Proc. 40, 671.
3 Present address: Patricia Moore, Ph.D., Natural Science Division, Pepperdine University, Malibu, CA 90265.
4 To whom reprint requests should be sent.
Manuscript received 5 January 1983.