Gender-specific effects of CNQX administered into the arcuate nucleus on ventilatory patterns in rats

This study evaluated the effect of microinjection of the non-N-methyl-D-asp artate (NMDA) receptor antagonist, cyano, 3-dihydro-7-nitrogluinoxaline-2, 3-dione (CNQX), into the arcuate nucleus of the hypothalamus on ventilation in male and female rats. Conscious rats received saline or 50, 100, or 200 pmol concentrations of CNQX on separate days. Significant interactions bet ween dose and gender were observed on frequency, inspiratory (Tr) and expir atory (TE) time, and tidal volume. CNQX depressed frequency, but increased tidal volume in female rats. Effects of CNQX in males on these ventilatory parameters were considerably less. In CNQX-treated females the decrease in frequency of breathing was primarily due to an increase in Tr. Exposure of CNQX-treated female rats to hypercapnia, but not to hypoxia transiently dec reased TI. No effect of CNQX was noted on oxygen consumption or body temper ature. Thus, non-NMDA receptors in the arcuate nucleus are involved in modu lating ventilatory patterns in a gender-specific manner independent of its effects on oxygen consumption or body temperature. (C) 1999 Elsevier Scienc e B.V. All rights reserved.