RESUMEN
Bone marrow adipose tissue (MAT) is formed by the accumulation of adipocytes in the bone marrow cavity. Previously, the function of MAT is mainly considered to be filled with bone marrow cavity for the mechanical support. However,with the in-depth study of MAT,it has been gradually understood that MAT is not only a part of the bone marrow microenvironment,may also be a new endocrine "organ". The main component of bone marrow adipocytes(BMA) plays a regulatory role in bone marrow and systemic metabolism through the autocrine and paracrine secretion of adiponectin, leptin, interleukin-6, and a series of cytokines. Though its biological characteristics are somewhat similar with white fat adipose tissue(WAT) and brown adipose tissue(BAT),there are some significant differences,so MAT is thought to be a special adipose tissue. MAT is also involved in the development of hematological diseases,metabolic diseases,degenerative diseases,and may affect their outcomes. MAT may be the auxiliary diagnostic criteria and treatment targets of such diseases. This article will review the MAT's own biological characteristics,the differences and associations among three types of adipose tissue and the link between MAT and the diseases,which aims to explore the new research direction through the profound understanding of MAT.
RESUMEN
OBJECTIVES: Bone marrow adipose tissue has been associated with low bone mineral density. However, no data exist regarding marrow adipose tissue in primary hyperparathyroidism, a disorder associated with bone loss in conditions of high bone turnover. The objective of the present study was to investigate the relationship between marrow adipose tissue, bone mass and parathyroid hormone. The influence of osteocalcin on the homeostasis model assessment of insulin resistance was also evaluated. METHODS: This was a cross-sectional study conducted at a university hospital, involving 18 patients with primary hyperparathyroidism (PHPT) and 21 controls (CG). Bone mass was assessed by dual-energy x-ray absorptiometry and marrow adipose tissue was assessed by 1H magnetic resonance spectroscopy. The biochemical evaluation included the determination of parathyroid hormone, osteocalcin, glucose and insulin levels. RESULTS: A negative association was found between the bone mass at the 1/3 radius and parathyroid hormone levels (r = -0.69; p<0.01). Marrow adipose tissue was not significantly increased in patients (CG = 32.8±11.2% vs PHPT = 38.6±12%). The serum levels of osteocalcin were higher in patients (CG = 8.6±3.6 ng/mL vs PHPT = 36.5±38.4 ng/mL; p<0.005), but no associations were observed between osteocalcin and insulin or between insulin and both marrow adipose tissue and bone mass. CONCLUSION: These results suggest that the increment of adipogenesis in the bone marrow microenvironment under conditions of high bone turnover due to primary hyperparathyroidism is limited. Despite the increased serum levels of osteocalcin due to primary hyperparathyroidism, these patients tend to have impaired insulin sensitivity.