Gender difference and change of α₁-adrenoceptors in the distal mesenteric arteries of streptozotocin-induced diabetic rats

Background: The purpose of this study was to evaluate the gender-related changes in the function and distribution of α1-adrenoceptors in the distal mesenteric artery of streptozotocin (STZ)-induced diabetic rats at the level of α1- adrenoceptor subtypes. Methods: Diabetes was induced by intravenous injection of STZ in a dose of 60 mg/kg through the tail vein in 8 weekold male or female Sprague-Dawley rats (n = 13/group). Age-matched normal rats (n = 15) were used as a control group. Four weeks after STZ injection, the change in mean arterial pressure caused by a 45o tilting was recorded. The α1-adrenoceptor subtypes mediating contractions of the distal mesenteric artery were investigated using the agonist, phenylephrine as well as subtype-selective antagonists including prazocin, 5-methylurapidil, and BMY 7378. The expression of α1-adrenoceptor subtypes of each artery was examined by immunofluorescence staining and western blotting using subtype selective antibodies. Results: Compared with normal male rats, the contractile response to phenylephrine was decreased in the distal mesenteric artery in normal female rats. Moreover, a decrease in contractile force was observed in STZ-induced diabetic rats compared with age-matched controls. Western blotting revealed that there was the difference between normal male and female rats in manifestation of the α1D-adrenoceptor. In STZ-induced male and female diabetic rats, all α1-adrenoceptor subtypes were decreased in distal mesenteric arteries, compared with normal rats. Conclusions: There was the gender-related functional difference of α1-adrenoceptors in normal rats. In both male and female rats, diabetes decreased the contractile response in mesenteric arteries, which might be caused by the overall change in α1-adrenoceptor.