Abstract
The first step in fat digestion occurs in the stomach, where 10–30% of dietary triacylglycerols are hydrolyzed to partial (di- and mono-) acylglycerols and free fatty acids. Preduodenal fat digestion is an important compensatory mechanism in the newborn because of immature pancreatic (lipase) and hepatic (bile acid synthesis) function. Since hydrolysis of fat in the stomach can be catalyzed by enzymes of lingual (Hamosh, M. (1979) Pediatr. Res. 13, 615–622) and possibly gastric origin, we have studied the developmental patter and quantitative contribution of these two enzymes to intragastric fat digestion by measuring lipase activity in homogenates of lingual glands and gastric mucosa of rats from birth until 60 days of age. Total lipolytic activity in rat gastric mucosa was only 2–10% of that in the lingual glands throughout the entire period studied. Lingual lipase activity increased steadily from birth until day 50, whereas the activity in the gastric mucosa reached peak levels at 17–20 days and declined sharply after weaning. Throughout the period of study - suckling, weaning, and young adulthood - lingual and gastric lipase had very similar characteristics: pH optimum in the range of 5.0–6.0 and 2.5–5.0-fold higher activity on medium-chain (tri[14C]octanoin than long-chain (tri[3H]olein) triacylglycerols. In the lingual glands, lipase activity was higher during fasting, probably because of accumulation of enzyme (without depletion during meals), whereas in the gastric mucosa lipase levels were higher after feeding, suggesting adsorption of lingual lipase (which reaches the stomach with the ingested food) onto the gastric mucosa. From birth to weaning, there was rapid and extensive hydrolysis of triacylglycerol in the stomach (decrease from 98 mol% in rat milk to 33.6–48.9 mol% in the stomach contents half an hour after feeding). The intragastric lipolysis remained almost constant from birth until day 20, in spite of a marked increase in food consumption, probably because of the continued rise of lingual lipase levels. The direct relationship between high intragastric lipolysis and high lingual lipase activity suggests that lingual lipase is the major digestive enzyme in the newborn.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.