Abstract
In order to investigate the alterations of bile acid synthesis in aging, we studied the rates of cholesterol 7α-hydroxylation, the rate-limiting step, in 28 patients of different ages (34-83 years old, 14 below and 14 above the age of 65) of both sexes. Hydroxylation rates were determined by tritium release assay after an intravenous bolus of [7α-3H]cholesterol. Cholesterol 7α-hydroxylation was significantly decreased in the older age group, compared to middle-aged subjects, both in males and females; moreover, a significant inverse correlation between hydroxylation rates and age was found in the whole sample (r = -0.56; P < 0.01) and in females, but not in males. The percent concentration of deoxycholic acid in plasma (determined by gas-liquid chromatography) was increased in older subjects. Plasma cholesterol and triglyceride levels were not related with age even though triglyceride concentrations tended to be lower in the older age group. Triglyceride, but not cholesterol levels, were directly correlated with hydroxylation rates (r = 0.45, P < 0.05). After cholestyramine treatment (8- 12 g/day for 4 weeks) a sharp increase in 7α-hydroxylation rates was observed in three elderly patients, accompanied by reduced levels of dihydroxylated bile acids. Our data are consistent with a reduced rate of conversion of cholesterol to bile acids with aging, particularly in females, and suggest a coordinate reduction of triglyceride production. Alterations of the quantitative and/or qualitative pattern of the bile acid pool recirculating to the liver may be responsible, at least in part, for the changes observed.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1001-1007 |
| Number of pages | 7 |
| Journal | Journal of Lipid Research |
| Volume | 34 |
| Issue number | 6 |
| State | Published - 1993 |
| Externally published | Yes |
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Keywords
- bile acid pool
- bile acid synthesis
- cholesterol homeostasis
- cholestyramine
- plasma cholesterol
- plasma triglycerides
ASJC Scopus subject areas
- Endocrinology
Cite this
Effect of aging on cholesterol 7α-hydroxylation in humans. / Bertolotti, M.; Abate, Nicola; Bertolotti, S.; Loria, P.; Concari, M.; Messora, R.; Carubbi, F.; Pinetti, A.; Carulli, N.
In: Journal of Lipid Research, Vol. 34, No. 6, 1993, p. 1001-1007.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Effect of aging on cholesterol 7α-hydroxylation in humans
AU - Bertolotti, M.
AU - Abate, Nicola
AU - Bertolotti, S.
AU - Loria, P.
AU - Concari, M.
AU - Messora, R.
AU - Carubbi, F.
AU - Pinetti, A.
AU - Carulli, N.
PY - 1993
Y1 - 1993
N2 - In order to investigate the alterations of bile acid synthesis in aging, we studied the rates of cholesterol 7α-hydroxylation, the rate-limiting step, in 28 patients of different ages (34-83 years old, 14 below and 14 above the age of 65) of both sexes. Hydroxylation rates were determined by tritium release assay after an intravenous bolus of [7α-3H]cholesterol. Cholesterol 7α-hydroxylation was significantly decreased in the older age group, compared to middle-aged subjects, both in males and females; moreover, a significant inverse correlation between hydroxylation rates and age was found in the whole sample (r = -0.56; P < 0.01) and in females, but not in males. The percent concentration of deoxycholic acid in plasma (determined by gas-liquid chromatography) was increased in older subjects. Plasma cholesterol and triglyceride levels were not related with age even though triglyceride concentrations tended to be lower in the older age group. Triglyceride, but not cholesterol levels, were directly correlated with hydroxylation rates (r = 0.45, P < 0.05). After cholestyramine treatment (8- 12 g/day for 4 weeks) a sharp increase in 7α-hydroxylation rates was observed in three elderly patients, accompanied by reduced levels of dihydroxylated bile acids. Our data are consistent with a reduced rate of conversion of cholesterol to bile acids with aging, particularly in females, and suggest a coordinate reduction of triglyceride production. Alterations of the quantitative and/or qualitative pattern of the bile acid pool recirculating to the liver may be responsible, at least in part, for the changes observed.
AB - In order to investigate the alterations of bile acid synthesis in aging, we studied the rates of cholesterol 7α-hydroxylation, the rate-limiting step, in 28 patients of different ages (34-83 years old, 14 below and 14 above the age of 65) of both sexes. Hydroxylation rates were determined by tritium release assay after an intravenous bolus of [7α-3H]cholesterol. Cholesterol 7α-hydroxylation was significantly decreased in the older age group, compared to middle-aged subjects, both in males and females; moreover, a significant inverse correlation between hydroxylation rates and age was found in the whole sample (r = -0.56; P < 0.01) and in females, but not in males. The percent concentration of deoxycholic acid in plasma (determined by gas-liquid chromatography) was increased in older subjects. Plasma cholesterol and triglyceride levels were not related with age even though triglyceride concentrations tended to be lower in the older age group. Triglyceride, but not cholesterol levels, were directly correlated with hydroxylation rates (r = 0.45, P < 0.05). After cholestyramine treatment (8- 12 g/day for 4 weeks) a sharp increase in 7α-hydroxylation rates was observed in three elderly patients, accompanied by reduced levels of dihydroxylated bile acids. Our data are consistent with a reduced rate of conversion of cholesterol to bile acids with aging, particularly in females, and suggest a coordinate reduction of triglyceride production. Alterations of the quantitative and/or qualitative pattern of the bile acid pool recirculating to the liver may be responsible, at least in part, for the changes observed.
KW - bile acid pool
KW - bile acid synthesis
KW - cholesterol homeostasis
KW - cholestyramine
KW - plasma cholesterol
KW - plasma triglycerides
UR - http://www.scopus.com/inward/record.url?scp=0027247545&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027247545&partnerID=8YFLogxK
M3 - Article
VL - 34
SP - 1001
EP - 1007
JO - Journal of Lipid Research
JF - Journal of Lipid Research
SN - 0022-2275
IS - 6
ER -