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Abstract(Please copy/paste the abstract send to the congress) : |
P108
HOMA-β AND PPAR-γ AS TWO EMERGING
PREDICTORS OF BONE RESORPTION IN
METABOLICALLY UNHEALTHY OBESITY
Z. Maghbooli 1, M. Talebpour 2, S. Emamgholipour 1,*, S.
Gorgani 1, A. Hossein-Nezhad 1
1Osteoporosis Research Center, Endocrinology and
Metabolism Clinical Sciences Institute of Tehran University
of Medical Sciences, 2Tehran University of Medical Sciences,
Tehran, Islamic Republic of Iran
Aims: To compare three different bone markers in metabolically
healthy and unhealthy obese and nonobese subjects according
to different metabolic healthy criteria. Also, we prepared
subcutaneous fat from all subjects to compare the levels
of some key molecules which involve in metabolic pathways
in the study groups.
Methods: In this study, subcutaneous fat was obtained from
40 subjects (mean age 38.72±13.82 year, 10 men); 14 healthy
normal-weight and 26 obese subjects. The protein expression
levels of peroxisome proliferator-activated receptor γ
(PPAR-γ), glucose transporter type 4 (GLUT4) and peroxisome
proliferator-activated receptor gamma coactivator 1α
(PGC-1α) and gene expression of PPAR-γ were examined
on subcutaneous fat as obesity key molecules. The serum
levels of osteocalcin, procollagen I aminoterminal propeptide
(P1NP), alkaline phosphatase (ALP), and β-crosslaps were
analyzed as bone turnover markers, as well as serum levels
of 25 (OH) vitamin D3, and PTH.We evaluated all metabolic
markers including FBS, insulin, HbA1C, HOMA-IR,
HOMA-β (%), Quicki (%), total cholesterol, HDL, LDL to
define the best model that may identify MHO individuals.
Also we examined the association between different criteria
of MHO with bone markers.
Results: The best model providing an association of metabolic
status with bone markers in obese subjects was HOMA-β
as an index of β-cell function (%B). Based on HOMA-β, all
participants were divided into three groups; normal weight
(HOMA-β<%100, n=14), obese (HOMA-β<%100, n=14)
and obese (HOMA-β>%100, n=12). There were significant
differences in BMI (p=0.0001), age (p=0.019), 25(OH)D3
(p=0.04), FBS (p=0.03), Insulin (p=0.0001), HOMA-IR
(p=0.015), HOMA-β (p=0.0001), Quicki (p=0.05), and β-
crosslaps (p=0.003) among groups. However, there were not
statistically significant differences in HbA1C and the serum
levels of P1NP, osteocalcin and PTH among groups. After
adjusting for age, gender and vitamin D deficiency, multivariate
analysis showed significant association of β-cell function
(HOMA-β >100 %) in obese subjects with increasing of β-crosslaps as a bone resorption marker (p=0.021). In this model,
there was also significant association between protein
levels of PPAR-γ in subcutaneous fat and plasma levels of
β-crosslaps (p=0.028).
Conclusion: Our data showed that HOMA-β, as an index of
β-cell function, can use in part of MHO criteria. In addition,
our findings propose novel role of HOMA-β and PPAR-γ in
predicting bone resorption in obese people and a possible new
molecular target in this research area. However, further studies
will be required to confirm this possibility. |