Endocrine Abstracts

JOINT3365

Objective: Body Mass Index (BMI) and bone age (BA) are key indicators for assessing an individual’s growth and development. Children with obesity may appear to have taller height but fail to achieve optimal adult height due to the accelerated maturation of the epiphyseal growth plates, resulting in premature bone age and termination of growth. In this study, we assessed the impact of obesity-induced hyperinsulinemia on linear growth trajectories and the underlying mechanisms involved, using a high-fat diet-induced obesity rat model.

Methods: Twelve healthy 1-week-old Sprague-Dawley rats, weighing between 60-80g, were randomized into two groups: a control group and an obese group, receiving a standard diet and high-fat diet, respectively. After 6 weeks of induction, weekly body weights and body lengths were assessed. At the end of the study, all rats were euthanized, and blood samples were collected for further analysis. Hematological parameters such as serum insulin levels were assessed using ELISA. Tibia and humerus bones were collected to assess the bone length. Growth plates were separated for histological, immunohistochemical, PCR and Western blot analyses.

Results: Serum insulin levels were significantly higher in the obese group compared to the control group (P < 0.01). Compared with the control group, the obese group exhibited significantly increased growth plate length (P < 0.01), particularly in the proliferative and hypertrophic zones. Immunohistochemical staining further revealed that elevated levels of aromatase and insulin receptor (IR) expression in growth plates were predominantly observed in the hypertrophic zone. The relative mRNA expression levels of both aromatase and insulin receptors in the growth plates of obese rats were significantly elevated compared to the control group (P < 0.01). Western blot analysis demonstrated significantly increased expression of both CYP19A1 and IR in the growth plates of obese rats (P < 0.01).

Conclusion: Advanced bone age observed in obese children could potentially be attributed to the insulin signaling pathway-mediated regulation of aromatase expression in the growth plate.