N G-methyl-L-arginine increases the hyperthermic effects of prostaglandin E 1

Abstract

The sympathetic firing rate of the nerves innervating interscapular brown adipose tissue (IBAT), IBAT and colonic temperatures (T IBAT and T C) were monitored in urethane-anaesthetized male Sprague-Dawley rats. These variables were measured for a period of 40 min before (baseline values) and 40 min after a 2 mg N G-methyl-L-arginine (NMA) injection plus an intracerebroventricular administration of 500 ng prostaglandin E 1 (PGE 1) into a lateral cerebral ventricle. No drug was injected in control rats. The results show that NMA enhances the increases in firing rate, T IBAT and T C induced by PGE 1. These findings indicate that an inhibitor of nitric oxide synthesis, such as NMA, increases the sympathetic and thermogenic responses to injection of PGE 1.