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Early postnatal development in the rat is characterized by accumulation of highly unsaturated triacylglycerols
1Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada.
Insights
Early postnatal growth significantly alters triacylglycerol (TG) species in rat liver and carcass. Essential fatty acids (EFA) show dramatic increases, particularly in liver TG, highlighting their structural importance.
Area of Science:
- Biochemistry
- Developmental Biology
- Nutritional Science
Background:
- Triacylglycerol (TG) metabolism is crucial for energy storage and signaling during development.
- Understanding changes in specific TG species and their fatty acid composition is vital for assessing nutritional requirements and metabolic adaptations in early life.
Purpose of the Study:
- To quantitatively analyze the changes in individual triacylglycerol (TG) species in the liver and carcass of rats during early postnatal growth.
- To determine the alterations in fatty acid composition within TG molecules during this critical developmental period.
Main Methods:
- Quantitative analysis of fatty acids and TG species using capillary gas liquid chromatography.
- Comparison of TG profiles in fetal (day 21) and neonatal (days 3 and 9) rat liver and carcass tissues.
Main Results:
- Total carcass TG increased 11-12 fold, with substantial increases in essential fatty acids (EFA), particularly n-6 EFA (34-44 fold) and n-3 EFA (19-29 fold).
- Neonatal liver TG increased 13-fold, with significant rises in n-6 EFA (34-fold) and n-3 EFA (65-fold).
- Highly unsaturated TG classes (C56-C64) rich in arachidonic and docosahexaenoic acids dominated liver TG at postnatal day 3.
Conclusions:
- Early postnatal development involves significant quantitative shifts in TG species, with a marked accumulation of EFA-rich TGs in both carcass and liver.
- TG species containing multiple long-chain polyunsaturated fatty acids are structurally important and may serve as precursors for phospholipid synthesis during rapid growth.
Abstract:
Our objective was to determine the quantitative changes of individual triacylglycerol (TG) species in liver and carcass during early postnatal growth. Pregnant rats were killed at d 21 of pregnancy, and neonatal rats were killed at d 3 or 9 after birth. Quantitative changes in fatty acids and TG species of fetal/neonatal liver and carcass were determined using capillary gas liquid chromatography. At postnatal d 3 or 9 compared with fetal d 21, total carcass TG increased 11- to 12-fold, with nonessential fatty acids increasing 8- to 9-fold, n-6 essential fatty acids (EFA) increasing 34- to 44-fold, and n-3 EFA increasing 19- to 29-fold, respectively. Total neonatal liver TG increased 13-fold from fetal d 21 to postnatal d 3, with a 6-fold increase in non-EFA, a 34-fold increase in total n-6 EFA and a 65-fold increase in total n-3 EFA. At postnatal d 3 compared with fetal d 21, larger molecular weight liver TG classes (C56-C64) increased 68-fold, followed by lower molecular weight TG classes C40-C48 (19-fold) with only a 6-fold increase in C50-C54. In liver, highly unsaturated TG classes (C56-C64) accounted for 49% of total TG at postnatal d 3 and consisted mainly of arachidonic, docosahexaenoic, and linoleic acids accompanied by palmitic and oleic acids. During early postnatal development, TG species containing one, two, or even three 20-22 EFA may be structurally important themselves or serve as direct substrates for synthesis of phospholipids.(ABSTRACT TRUNCATED AT 250 WORDS)