title: Age-related effects of fasting on ketone body production during lipolysis in rats.
abstract: OBJECTIVE
  The age-related effects of fasting on lipolysis, the production of ketone bodies, and plasma insulin levels were studied in male 3-, 8-, and 32-week-old Sprague-Dawley rats.
  
  
  METHODS
  The rats were divided into fasting and control groups. The 3-, 8- and 32-week-old rats tolerated fasting for 2, 5, and 12 days, respectively.
  
  
  RESULTS
  Fasting markedly reduced the weights of perirenal and periepididymal white adipose tissues in rats in the three age groups. The mean rates of reduction in both these adipose tissue weights during fasting periods were higher in the order of 3 > 8 > 32-week-old rats. Fasting transiently increased plasma free fatty acid (FFA), total ketone body, β-hydroxybutyrate, and acetoacetate concentrations in the rats in the three age groups. However, plasma FFA, total ketone body, β-hydroxybutyrate, and acetoacetate concentrations in the 3-week-old rats reached maximal peak within 2 days after the onset of fasting, although these concentrations in the 8- and 32-week-old rats took more than 2 days to reach the maximal peak. By contrast, the augmentation of plasma FFA, total ketone body, β-hydroxybutyrate, and acetoacetate concentrations in the rats in the three age groups had declined at the end of each experimental period. Thus, the capacity for fat mobilization was associated with tolerance to fasting. Plasma insulin concentrations in the rats in the three age groups were dramatically reduced during fasting periods, although basal levels of insulin were higher in the order of 32 > 8 > 3 week-old rats.
  
  
  CONCLUSIONS
  These results suggest that differences in fat metabolism patterns among rats in the three age groups during prolonged fasting were partly reflected the metabolic turnover rates, plasma insulin levels, and amounts of fat storage.
authors.affiliation: Laboratory of Physiological Sciences, School of Human Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192, Japan.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Higashino-Matsui
authors.forename: Ken
authors.initials: K
authors.lastname: Shirato
authors.forename: Yuko
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Yu
authors.initials: Y
authors.lastname: Kawashima
authors.forename: Yui
authors.initials: Y
authors.lastname: Someya
authors.forename: Shogo
authors.initials: S
authors.lastname: Sato
authors.forename: Akira
authors.initials: A
authors.lastname: Shiraishi
authors.forename: Manabu
authors.initials: M
authors.lastname: Jinde
authors.forename: Akiko
authors.initials: A
authors.lastname: Matsumoto
authors.forename: Hisashi
authors.initials: H
authors.lastname: Ideno
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tachiyashiki
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Imaizumi
mesh_terms: D000090:Acetoacetates / Q000097:blood / Q000378:metabolism*; D000273:Adipose Tissue / Q000378:metabolism*; D000375:Aging; D000818:Animals; D001835:Body Weight; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood / Q000378:metabolism*; D007328:Insulin / Q000097:blood / Q000378:metabolism; D007657:Ketone Bodies / Q000097:blood / Q000378:metabolism*; D008066:Lipolysis; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000090:Acetoacetates; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D007657:Ketone Bodies; C016635:acetoacetic acid