Adipose tissue has been shown to release a transferable factor that relaxes vascular smooth muscle; the precise nature of this factor is as yet unknown (Gollasch & Dubrowska 2004). It has been suggested that the vasodilator function of perivascular fat is reduced in obesity (Greenstein et al. 2009) and that activity of 11ß-HSD-1 reductase is elevated in obese patients (Rask et al. 2002). We thus wanted to determine whether steroids modulate the vasodilator mechanism of adipose tissue.

Mesenteric small arteries from adult Sprague-Dawley rats were isolated and mounted in a Mulvany-Halpern myograph. All vessels were initially cleaned of perivascular fat and their noradrenaline sensitivity determined. Subsequently, perivascular fat was wrapped around every other blood vessel and noradrenaline sensitivity determined again. Finally corticosterone (10 mM) was added 10 min before a third determination of noradrenaline sensitivity.

Application of fat caused a significant reduction in noradrenaline sensitivity (D(log EC50) -0.581 ± 0.109, n=7) and a reduction in maximal response (-12.7 ± 3.8 %). Addition of corticosterone partially antagonised the effect of fat: sensitivity increased by D(log EC50) 0.345 ± 0.121 compared to fat without corticosterone. In vessels without perivascular fat corticosterone did not induce any significant effects.

These preliminary data suggest that steroids may acutely modulate the vasodilator mechanism of perivascular fat.

Gollasch M, Dubrovska G. Trends Pharmacol Sci 2004;25:647–53.

Greenstein AS, Khavandi K, Withers SB, Sonoyama K, Clancy O, Jeziorska M, et al. Circulation 2009;119:1661–70.

Rask E, Walker BR, Soderberg S, Livingstone DE, Eliasson M, Johnson O, et al. J Clin Endocrinol Metab 2002;87:3330–6.