Measurement of bioactive osteocalcin in humans using a novel immunoassay reveals association with glucose metabolism and ß-cell function.
Am J Physiol Endocrinol Metab
; 318(3): E381-E391, 2020 03 01.
Article
em En
| MEDLINE
| ID: mdl-31935114
ABSTRACT
Osteocalcin (OCN) is a bone-derived hormone involved in the regulation of glucose metabolism. In serum, OCN exists in carboxylated and uncarboxylated forms (ucOCN), and studies in rodents suggest that ucOCN is the bioactive form of this hormone. Whether this is also the case in humans is unclear, because a reliable assay to measure ucOCN is not available. Here, we established and validated a new immunoassay (ELISA) measuring human ucOCN and used it to determine the level of bioactive OCN in two cohorts of overweight or obese subjects, with or without type 2 diabetes (T2D). The ELISA could specifically detect ucOCN concentrations ranging from 0.037 to 1.8 ng/mL. In a first cohort of overweight or obese postmenopausal women without diabetes (n = 132), ucOCN correlated negatively with fasting glucose (r = -0.18, P = 0.042) and insulin resistance assessed by the homeostatic model assessment of insulin resistance (r = -0.18, P = 0.038) and positively with insulin sensitivity assessed by a hyperinsulinemic-euglycemic clamp (r = 0.18, P = 0.043) or insulin sensitivity index derived from an oral glucose tolerance test (r = 0.26, P = 0.003). In a second cohort of subjects with severe obesity (n = 16), ucOCN was found to be lower in subjects with T2D compared with those without T2D (2.76 ± 0.38 versus 4.52 ± 0.06 ng/mL, P = 0.009) and to negatively correlate with fasting glucose (r = -0.50, P = 0.046) and glycated hemoglobin (r = -0.57, P = 0.021). Moreover, the subjects with ucOCN levels below 3 ng/mL had a reduced insulin secretion rate during a hyperglycemic clamp (P = 0.03). In conclusion, ucOCN measured with this novel and specific assay is inversely associated with insulin resistance and ß-cell dysfunction in humans.
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Texto completo:
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Base de dados:
MEDLINE
Assunto principal:
Testes de Função Pancreática
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Osteocalcina
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Células Secretoras de Insulina
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Glucose
Tipo de estudo:
Etiology_studies
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Incidence_studies
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Observational_studies
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Prognostic_studies
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Risk_factors_studies
Limite:
Adolescent
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Adult
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Aged
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Animals
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Female
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Humans
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Male
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Middle aged
Idioma:
En
Revista:
Am J Physiol Endocrinol Metab
Assunto da revista:
ENDOCRINOLOGIA
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FISIOLOGIA
/
METABOLISMO
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Canadá