Relationship between plasma level of leptin and the expression of leptin receptor in human adrenal tissues and tumors

Objective To compare the mRNA, protein expression of long leptin receptor (Ob-Rb)in human adrenal tissues and tumors and observe the plasma level of leptin in primary aldosteronism (PA),cortisol-secreting tumors (CS) and pheochromacytomas (PHEO). Methods Total RNA and protein were extracted from 6 normal human adrenal glands, 10 CS, 20 PHEO; and 14 aldosterone-producing adenomas (APA) (RNA), 10 APA (protein); plasma samples were drawn from 20 controls, 15 PHEO, 29 PA and 11 CS. Results The mRNA and protein of Ob-Rb were widely expressed in human adrenal glands and tumors. The mRNA (0. 32 ±0. 12) and protein (1.31 ±0. 26) expressions of Ob-Rb were higher in normal human adrenal cortex (C) than all other tissues (P ＜0. 05) while the mRNA expression of Ob-Rb in APA (0. 15 ± 0. 10) was higher than CS (0. 05 ± 0. 02) (P ＜ 0. 05). The mRNA expression of Ob-Rb in APA was positively correlated with plasma supine aldosterone level (r= 0. 670, P= 0. 024). The mRNA expression of Ob-Rb in CS was positively correlated with 24-hour urinary free cortisol level(r=0. 870, P=0. 005). The plasma level of leptin was higher in CS than in non-CS groups (P= 0. 001). Conclusions Ob-Rb is widely expressed in adrenal tissues and tumors. There is a differential expression in various tissues. Further studies are warranted to understand the relationship between leptin and adrenal gland. Key words: Adrenal gland neoplasms; Leptin; Leptin receptor