Aging-associated increase in intestinal absorption of macromolecules

Area of Science:

• Gastroenterology
• Aging Research
• Toxicology

Background:

• Intestinal permeability is crucial for nutrient absorption and barrier function.
• Aging is associated with physiological changes that may affect gut barrier integrity.
• Polyethylene glycol (PEG) is commonly used to assess intestinal permeability.

Purpose of the Study:

• To investigate the effect of aging on intestinal permeability in rats using various molecular weights of PEG 400.
• To determine if aging alters the absorption of different sized molecules across the intestinal barrier.

Main Methods:

• Aging rats (34 vs. 133 weeks) received an oral gavage of PEG 400.
• Urine was collected for 6 hours post-administration.
• Urinary excretion of PEG 400 was quantified using gas-liquid chromatography.

Main Results:

• Total urinary excretion of PEG 400 significantly increased with age.
• Younger rats excreted 34.3% of the dose, while older rats excreted 43.6%.
• The effect was more pronounced for higher molecular weight PEGs; PEG 282 excretion decreased by 10.5%, while PEG 634 excretion increased by 11.4% with aging.

Conclusions:

• Intestinal permeability to higher molecular weight PEG increases with age in rats.
• The aging intestinal barrier may be less efficient in preventing the absorption of larger molecules.
• This finding suggests a potential for increased absorption of harmful environmental substances in aging animals.