Glucocorticoids modulate human brown adipose tissue thermogenesis in vivo

INTRODUCTION

Brown adipose tissue (BAT) is a thermogenic organ with substantial metabolic capacity and has important roles in the maintenance of body weight and metabolism. Regulation of BAT is primarily mediated through the β-adrenoceptor (β-AR) pathway. The in vivo endocrine regulation of this pathway in humans is unknown. The objective of our study was to assess the in vivo BAT temperature responses to acute glucocorticoid administration.

METHODS

We studied 8 healthy male volunteers, not pre-selected for BAT presence or activity and without prior BAT cold-activation, on two occasions, following an infusion with hydrocortisone (0.2mg.kg^-1.min^-1 for 14h) and saline, respectively. Infusions were given in a randomized double-blind order. They underwent assessment of supraclavicular BAT temperature using infrared thermography following a mixed meal, and during β-AR stimulation with isoprenaline (25ng.kg fat-free mass^-1.min^-1 for 60min) in the fasting state.

RESULTS

During hydrocortisone infusion, BAT temperature increased both under fasting basal conditions and during β-AR stimulation. We observed a BAT temperature threshold, which was not exceeded despite maximal β-AR activation. We conclude that BAT thermogenesis is present in humans under near-normal conditions. Glucocorticoids modulate BAT function, representing important physiological endocrine regulation of body temperature at times of acute stress.

Alpha1B adrenoceptor expression is a marker of reduced survival and increased tumor recurrence in patients with endometrioid ovarian cancer

AIM: To investigate the expression patterns of different adrenoceptor isoforms in ovarian cancer and their association with survival and tumor recurrence.

METHODS: The protein expression levels of α1B, α2C and β2 adrenoceptor were assessed in unselected ovarian cancer using immunohistochemistry on microarrayed archival tissue samples. A database containing clinical and pathology parameters and follow-up was used to investigate the association between adrenoceptor isoform expression with ovarian specific survival and tumor recurrence, using univariate and multivariate statistical analysis.

RESULTS: Expression of α1B showed an association with reduced ovarian specific survival (P = 0.05; CI: 1.00-1.49) and increased tumor recurrence (P = 0.021, CI: 1.04-1.69) in the whole patient group. On sub-analysis the expression of α1B in endometrioid cancers (χ² = 5.867, P = 0.015) was found to predict reduced ovarian specific survival and increased tumor recurrence independently of tumor grade, clinical stage and chemotherapy. An association with clinical outcome was not seen for α2C or β2 AR.

CONCLUSION: Alpha1B adrenoceptor protein was found to predict increased risk of tumor recurrence and reduced mortality in patients with endometrioid type ovarian cancer and should be investigated as a biomarker for identifying patients at increased risk of disease progression. Furthermore, α adrenergic receptor antagonists with α1B selectivity should be investigated as a possible adjuvant therapy for treating patients with endometrioid cancer. Proof of principle could be tested in a retrospective population study.