Aims: 

To analyze effects of ageing on lipid metabolism as revealed by fasting and refeeding or by short-term dietary restriction (SDR) with subsequent ad libitum feeding.

Methods: 

Young-adult and old Wistar-Han rats were either fasted for 48 h and subsequently refed for days, or subjected for 30 days to a diet restricted to 60% of normal food intake and subsequently fed ad lib. The activity of lipogenic enzymes examined in the liver and white adipose tissue (WAT) from 3 locations.

Results: 

Fasting increased serum free fatty acids levels in young animals, however, not in old ones. In the liver of control old rats the activity of fatty acid synthase (FAS) was twice higher than in young animals whereas the activity of ATP-citrate lyase (ACL) was similar in both age groups. In various types of WAT old rats had diminished levels of basal and refeeding-induced FAS and ACL activities as compared to young ones. In young, but not old rats, SDR elevated ACL activity in intra-abdominal WAT, which further increased after return to ad lib feeding. Return to the normal diet elevated serum leptin levels, although they remained lower than in control young and old rats throughout 6 days of ad libitum feeding.

Conclusion: 

Effectiveness of lipolysis and lipogenesis in WAT decreases in old rats. SDR counteracts the effects of ageing, since it maintains high sensitivity of WAT to lipogenic and lipolytic stimuli. However, the metabolic effects of SDR aimed at weight reduction of the elderly should be carefully examined to avoid its adverse consequences when returning from calorie restriction regimes to normal food intake.