Effect of hydroxycitrate on respiratory quotient, energy expenditure, and glucose tolerance in male rats after a period of restrictive feeding.
OBJECTIVE
Recently we demonstrated that hydroxycitrate (HCA) suppresses food intake and body weight regain in male rats after substantial body weight loss. However, it is not known whether HCA also affects the respiration quotient (RQ), energy expenditure (EE), and glucose tolerance in this animal model.


METHODS
Twenty-four male rats (initial body weight, 378 +/- 3 g) were fed restrictively (10 g/d) for 10 d and then given ad libitum access to a high-glucose diet supplemented with 3% HCA for 6 d. Controls received the same diet without the supplement. RQ and EE were measured during ad libitum days 1, 2, and 6. An oral glucose tolerance test was performed on ad libitum day 4 or 5.


RESULTS
HCA decreased RQ and EE during ad libitum days 1 and 2. In all probability, these findings reflect a decrease in de novo lipogenesis. On ad libitum day 6, RQ and EE did not differ between treatment groups. HCA suppressed food intake during the first 3 d ad libitum, but overall body weight regain was not decreased in the HCA group. The oral glucose tolerance test showed that HCA significantly decreased the increase in plasma glucose from baseline (Deltaglucose) and tended to decrease the area under the curve for glucose. Deltainsulin and area under the curve for insulin did not differ between groups.


CONCLUSIONS
These results indicate that, in this animal model, HCA suppresses de novo lipogenesis. Moreover, HCA may improve glucose tolerance.
Institute of Animal Sciences, Swiss Federal Institute of Technology, Schwerzenbach, Switzerland. monika.leonhardt@inw.agrl.ethz.ch
Monika
M
Leonhardt
Börk
B
Balkan
Wolfgang
W
Langhans
D000818:Animals; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism*; D002153:Calorimetry, Indirect; D002951:Citrates / Q000494:pharmacology*; D004734:Energy Metabolism / Q000187:drug effects*; D005508:Food Deprivation / Q000502:physiology; D008055:Lipids / Q000096:biosynthesis*; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D001786:Blood Glucose; D002951:Citrates; D008055:Lipids; C007999:hydroxycitric acid