Increase in sphingolipid catabolic enzyme activity during aging.
OBJECTIVE
To understand the contribution of sphingolipid metabolism and its metabolites to development and aging.


METHODS
A systemic analysis on the changes in activity of sphingolipid metabolic enzymes in kidney, liver and brain tissues during development and aging was conducted. The study was conducted using tissues from 1-day-old to 720-day-old rats.


RESULTS
Catabolic enzyme activities as well as the level of sphingomyelinase (SMase) and ceramidase (CDase) were higher than that of anabolic enzyme activities, sphingomyelin synthase and ceramide synthase. This suggested an accumulation of ceramide and sphingosine during development and aging. The liver showed the highest neutral-SMase activity among the tested enzymes while the kidney and brain exhibited higher neutral-SMase and ceramidase activities, indicating a high production of ceramide in liver and ceramide/sphingosine in the kidney and brain. The activities of sphingolipid metabolic enzymes were significantly elevated in all tested tissues during development and aging, although the onset of significant increase in activity varied on the tissue and enzyme type. During aging, 18 out of 21 enzyme activities were further increased on day 720 compared to day 180.


CONCLUSIONS
Differential increases in sphingolipid metabolic enzyme activities suggest that sphingolipids including ceramide and sphingosine might play important and dynamic roles in proliferation, differentiation and apoptosis during development and aging.
Sacket
Santosh J
SJ
Laboratories of Pharmacology, College of Pharmacy (BK21 Project) and Longevity Institute of Life Science and Technology, Pusan National University, Busan 609-735, Republic of Korea.
Chung
Hae-Young
HY
Okajima
Fumikazu
F
Im
Dong-Soon
DS
D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000378:metabolism; D055572:Ceramidases / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D055576:Neutral Ceramidase / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013107:Sphingolipids / Q000378:metabolism; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D013379:Substrate Specificity; D017855:Transferases (Other Substituted Phosphate Groups) / Q000378:metabolism
D013107:Sphingolipids; D010088:Oxidoreductases; C108138:dihydroceramide desaturase; D017855:Transferases (Other Substituted Phosphate Groups); C070186:phosphatidylcholine-ceramide phosphocholine transferase; D013108:Sphingomyelin Phosphodiesterase; D055572:Ceramidases; D055576:Neutral Ceramidase