OBJECTIVES: Intake of multivitamin preparations is very common in developed countries. However, excessive intake of vitamin A was associated with increased bone fragility. The aim of this study was to determine if chronic administration of the active metabolite of vitamin A all-trans-retinoic acid (ATRA) in slight excess is associated with changes of bone turnover and density in intact and castrated mice. METHOD: Three mo old male mice (C57B1/6) intact and castrated were injected intraperitonealy with 10 mg/kg/d of the ATRA or vehicle (control) once daily for 3 wk. The bone density, ash weights, calcium, and phosphorus content of the femur were measured. Plasma tartrate-resistant acid phosphatase (Tr-ACP) and serum bone alkaline phosphatase (B-ALP) were determined. RESULTS: ATRA decreased bone density in both groups; however, this effect was more pronounced in castrated animals (1.487 ± 0.04 to 1,360 ± 0.05 g/cm(3)) than in intact mice (1.570 ± 0.03 to 1.510 ± 0.03 g/cm(3)). Bone density correlated with decreased B-ALP and increased Tr-ACP in ATRA-treated mice. ATRA treatment led to significantly lower thickness of cortical bone both in the intact and castrated animals. CONCLUSION: Our results indicate that repeated administration of ATRA in slight excess leads to significant bone loss both in intact and castrated mice. This effect was more pronounced in testosterone-deficient animals. Testosterone deficiency as occurs following castration may sensitize the bone to resorption mediated by ATRA. Therefore, chronic vitamin A administration may be a risk factor for osteoporosis, especially in older and testosterone-depleted subjects.

• MeSH
• alkalická fosfatasa krev   MeSH
• femur chemie   účinky léků   MeSH
• fosfor krev   MeSH
• izoenzymy krev   MeSH
• kostní denzita účinky léků   MeSH
• kyselá fosfatasa krev   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• orchiektomie MeSH
• osteoporóza chemicky indukované   patofyziologie   MeSH
• rizikové faktory MeSH
• testosteron krev   nedostatek   MeSH
• testy toxicity MeSH
• tretinoin aplikace a dávkování   toxicita   MeSH
• vápník krev   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH