Adipocyte Browning and Higher Mitochondrial Function in Periadrenal But Not SC Fat in Pheochromocytoma

Context: Patients with pheochromocytoma (pheo) show presence of multilocular adipocytes that express uncoupling protein 1 within periadrenal (pADR) and omental (OME) fat depots. It has been hypothesized that this is due to adrenergic stimulation by catecholamines produced by the pheo tumors. Objective: To characterize the prevalence and respiratory activity of brown-like adipocytes within pADR, OME, and SC fat depots in human adult pheo patients. Design: This was an observational cohort study. Setting: The study took place in a university hospital. Patients: We studied 46 patients who underwent surgery for benign adrenal tumors (21 pheos and 25 controls with adrenocortical adenomas). Main outcome measure: We characterized adipocyte browning in pADR, SC, and OME fat depots for histological and immunohistological features, mitochondrial respiration rate, and gene expression. We also determined circulating levels of catecholamines and other browning-related hormones. Results: Eleven of 21 pheo pADR adipose s...