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Age-related changes in polyamine biosynthesis after fasting and refeeding
K Yoshinaga1, J Ishizuka, B M Evers
1Department of Surgery, University of Texas Medical Branch, Galveston 77555.
Experimental Gerontology
|November 1, 1993
Summary
Aging alters polyamine biosynthesis in the gut. Ornithine decarboxylase (ODC) activity and polyamine levels show reduced control in aged rats, impacting intestinal function.
Area of Science:
- Gastroenterology
- Aging Research
- Molecular Biology
Background:
- Polyamines are essential for cell growth and proliferation.
- Ornithine decarboxylase (ODC) is a key enzyme in polyamine biosynthesis.
- Aging may affect intestinal polyamine metabolism and ODC activity.
Purpose of the Study:
- To investigate the impact of aging on ODC activity and polyamine biosynthesis in the proximal small intestine.
- To examine the effects of fasting and refeeding on these parameters in young and aged rats.
Main Methods:
- Study groups: Young (4-month old) and aged (26- to 27-month old) male Fisher 344 rats.
- Experimental model: Fasting and refeeding protocol.
- Measurements: Polyamines (putrescine, spermidine, spermine) and ODC activity in the proximal small intestine.
Main Results:
- Aged rats had higher basal polyamine levels and ODC activity than young rats.
- Fasting reduced polyamines in aged rats but not young rats; ODC activity decreased in both groups.
- Refeeding stimulated ODC activity and putrescine levels more robustly in young rats than aged rats, with sustained lower levels of spermidine and spermine in aged rats.
Conclusions:
- Aging significantly alters the regulation of polyamine biosynthesis and ODC activity in the rat proximal small intestine.
- The adaptive response to fasting and refeeding is impaired in aged rats.
- These findings suggest a loss of regulatory control over gut polyamine metabolism and proliferation with advancing age.