Related Experiment Videos
Carnitine acetyltransferase in developing mammals
Insights
Mitochondrial carnitine acetyltransferase (CAT) activity increases during development in rat liver and brown fat. This mitochondrial enzyme, unlike the microsomal form, is likely involved in fatty acid oxidation.
Area of Science:
- Biochemistry
- Developmental Biology
- Metabolism
Background:
- Carnitine acetyltransferase (CAT) plays a role in energy metabolism.
- Understanding CAT activity during development is crucial for insights into metabolic adaptations.
Purpose of the Study:
- To investigate the developmental changes in carnitine acetyltransferase (CAT) activity in rat, rabbit, and guinea pig liver and brown adipose tissue.
- To differentiate the roles of mitochondrial and microsomal CAT in fatty acid oxidation.
Main Methods:
- Assessed mitochondrial and microsomal carnitine acetyltransferase (CAT) activity.
- Measured catalase activity as a peroxisomal marker.
- Compared enzyme activities in liver and brown adipose tissue across different developmental stages and species.
Main Results:
- Mitochondrial CAT activity increased perinatally in rat liver and brown adipose tissue, with higher absolute levels in brown fat.
- Microsomal CAT activity increased in rat brown adipose tissue and liver postnatally.
- Hepatic mitochondrial CAT activity was significantly higher prenatally in guinea pigs and rabbits compared to rats.
Conclusions:
- Mitochondrial carnitine acetyltransferase (CAT) is likely directly involved in fatty acid oxidation.
- The function of microsomal CAT remains unclear.
- Species-specific differences in hepatic mitochondrial CAT activity exist during development.
Abstract:
Carnitine acetyltransferase (CAT) activity was determined in mitochondria and microsomes of liver and brown adipose tissue in fetal and postnatal rats, rabbits and guinea pigs. In rat liver and brown adipose tissue, mitochondrial CAT activity increased perinatally. Microsomal CAT activity also increased in brown adipose tissue. In liver, however, a rise was first noted after the 20th postnatal day. The ratio of mitochondrial to microsomal activity was higher in brown fat than liver throughout the period studied. Absolute values for both were always much higher in brown adipose tissue than in liver. Catalase activity (an enzyme localized in the peroxisomes) in rat liver increased after day 20 while in brown adipose tissue it attained a peak at 7 days after birth. At all times, hepatic activity exceeded activity in brown adipose tissue. The ratio on day 30 was 1 (brown adipose tissue) to 25 (liver). In both guinea pigs and rabbits, hepatic mitochondrial CAT activity was 10- to 20-fold higher than in the rat already prenatally. Microsomal activity, on the other hand, was approximately the same in all three species. It is concluded that probably only the mitochondrial CAT is directly related to fatty acid oxidation. The role of microsomal enzyme remains unclear.