ABSTRACT
Postmenopausal bone loss is a major public health concern. Although drug therapies are available, women are interested in alternative/adjunct therapies to slow down the bone loss associated with ovarian hormone deficiency. The purpose of this study was to determine whether dietary supplementation of l-carnitine can influence bone density and slow the rate of bone turnover in an aging ovariectomized rat model. Eighteen-month-old Fisher-344 female rats were ovariectomized and assigned to two groups: (1) a control group in which rats were fed ad libitum a carnitine-free (-CN) diet (AIN-93M) and (2) another fed the same diet but supplemented with l-carnitine (+CN). At the end of 8 weeks of feeding, animals were sacrificed and bone specimens were collected for measuring bone mineral content (BMC) and density (BMD) using dual energy X-ray absorptiometry. Femoral microarchitectural properties were assessed by microcomputed tomography. Femoral mRNA levels of selected bone matrix proteins were determined by northern blot analysis. Data showed that tibial BMD was significantly higher in the rat fed the +CN diet than those fed the -CN (control) diet. Dietary carnitine significantly decreased the mRNA level of tartrate-resistant acid phosphatase (TRAP), an indicator of bone resorption by 72.8%, and decreased the mRNA abundance of alkaline phosphatase (ALP) and collagen type-1 (COL), measures of bone formation by 63.6% and 61.2%, respectively. The findings suggest that carnitine supplementation slows bone loss and improves bone microstructural properties by decreasing bone turnover.
Subject(s)
Aging/physiology , Bone Density/drug effects , Carnitine/pharmacology , Dietary Supplements , Ovariectomy , Acid Phosphatase/genetics , Acid Phosphatase/metabolism , Alkaline Phosphatase/genetics , Alkaline Phosphatase/metabolism , Animals , Collagen Type I/genetics , Collagen Type I/metabolism , Eating , Female , Femur/drug effects , Femur/physiology , Isoenzymes/genetics , Isoenzymes/metabolism , Lumbar Vertebrae/drug effects , Lumbar Vertebrae/physiology , Osteoporosis/prevention & control , Phytotherapy , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Rats, Inbred F344 , Tartrate-Resistant Acid Phosphatase , Tibia/drug effects , Tibia/physiology , Vitamin B Complex/pharmacology , Weight GainABSTRACT
The objective of this study was to determine whether dietary L-carnitine can influence the status of alpha-tocopherol, retinol and selected lipid parameters in aging ovariectomized rats, an animal model for the menopausal state. Fourteen Fisher-344 female rats 18 months old were acclimated for 4 weeks and ovarectomized. Seven rats per treatment were assigned to either a control group fed ad libitum AIN-93M diet or a carnitine group fed the same diet supplemented with L-carnitine. After an 8-week feeding period, blood and selected tissues were taken for analyses. No differences were noted in food intake, body weight, or organ weights due to L-carnitine. Dietary carnitine significantly increased liver alpha-tocopherol and tended to increase plasma alpha-tocopherol (P<.09). No changes in alpha-tocopherol were observed in other tissues including the brain, lungs and retroperitoneal fat. Retinol levels in plasma and tissues were not affected by supplemental L-carnitine. Significant decreases in liver and plasma triglyceride (TG) levels were noted, suggesting increased utilization of fatty acids. No differences were observed in the fatty acid profile of tissues. The results provide evidence that dietary supplementation of L-carnitine enhances the alpha-tocopherol status and improves the utilization of fat leading to lowering of the liver and plasma levels of TG in aging ovariectomized rats. Whether supplemental L-carnitine may be of benefit to postmenopausal women in lowering plasma TG and improving the antioxidant status remains to be studied.
Subject(s)
Carnitine/pharmacology , Liver/drug effects , Triglycerides/metabolism , alpha-Tocopherol/metabolism , Aging , Animals , Body Weight/drug effects , Carnitine/administration & dosage , Dietary Supplements , Female , Liver/metabolism , Ovariectomy , Rats , Rats, Inbred F344 , Triglycerides/bloodABSTRACT
This study was conducted to determine whether the feeding of dietary L-carnitine (CN) improves the intestinal absorption of fat and alpha-tocopherol (alphaTOH) in ovariectomized (OX) rats. OX adult rats were weight-matched and assigned to 2 groups fed a modified AIN-93G diet containing alphaTOH-stripped soybean oil without (-CN) or with (+CN) supplemental CN at 150 mg/kg diet. At 5 wk, each rat with a lymph cannula was infused intraduodenally at 3.0 mL/h with a lipid emulsion consisting of 565 micromol triolein labeled with (14)C ((14)C-OA), 3.6 micromol alphaTOH, and 396 micromol sodium taurocholate in 24 mL PBS buffer. Lymph was collected hourly for 8 h and analyzed for lipids. The lymphatic absorption of alphaTOH for 8 h in +CN rats (899 +/- 201 nmol) was higher (P < 0.05) than in -CN rats (587 +/- 92 nmol). The absorption of (14)C-OA in +CN rats (53.5 +/- 4.0% dose/8 h) also was increased (P < 0.05) compared with -CN rats (47.6 +/- 5.0% dose/8 h). Lymph flow did not differ between the groups. When bile was diverted but with infusion of sodium taurocholate, the lymphatic absorption of lipids did not differ. The present study provides evidence that dietary CN enhances the rates and amounts of lymphatic absorption of alphaTOH and fat in OX rats. Our findings suggest that dietary CN may influence the process of lipid packaging and absorption by the enterocyte in OX rats, and may explain in part the increased status of alphaTOH in CN-fed animals.
