Gender-modulated endogenous baseline neuropeptide Y Y1-receptor activation in the hindlimb of Sprague-Dawley rats

Abstract

This study examined the effect of neuropeptide Y Y1-receptor blockade both alone, and in interaction with α1-adrenoceptor antagonism, on basal hindlimb vascular conductance in male and female Sprague-Dawley rats. Hindlimb vascular conductance was measured during infusion of BIBP3226 (Y1-receptor antagonist; 100 μg kg-1), prazosin (α1-receptor antagonist; 20 μg kg-1), and combined blockade. In males, vascular conductance increased 1.1 ± 0.3 μl min-1 mmHg-1 above baseline with BIBP3226, and 2.4 ± 0.4 μl min-1 mmHg-1 above baseline with prazosin (both P < 0.05). The increase in vascular conductance during combined blockade (5.1 ± 0.7 μl min-1 mmHg-1) was greater than the sum of the independent BIBP3226 and prazosin responses (P < 0.05). In females, basal hindlimb vascular conductance was unaffected by Y1-receptor blockade. However, α1-receptor blockade resulted in a 3.5 ± 0.6 μl min-1 mmHg-1 increase in vascular conductance above baseline, which was not different than the combined blockade condition. Males had greater skeletal muscle neuropeptide Y concentration (P < 0.05; ELISA than females. Furthermore, compared with females, male skeletal muscle contained greater Y1-receptor expression (P < 0.05; Western blot). It was concluded that, under baseline conditions, agonist and receptor-based mechanisms for Y1-receptor dependent control of vascular conductance in skeletal muscle was greater in male versus female rats. © The Physiological Society 2004.