Abstract
Our previous studies showed that an arousal/yawning response was evoked by microinjection of several agents (L-glutamate, cyanide, histamine etc) into the paraventricular nucleus (PVN) in an anesthetized, spontaneously breathing rat. In this study we examined involvement of CRF neurons in the arousal/yawning response by double-immunohistochemistry against c-fos and CRF. The activating site within the brain during the arousal/yawning response was observed by c-fos expression. The experiment was applied to two groups of anesthetized rats. In the experimental group frequent yawns were induced by injecting L-glutamate into the PVN, while in the control group no injection was made. In the experimental group, c-fos/CRF double-labelled neurons were found in the PVN, especially in the dorsal area of the medial parvocellular subdivision and the rostral area of anterior parvocellular subdivision. We therefore conclude that CRF neurons in the PVN are involved in the arousal/yawning response. Hemispheric asymmetry of c-fos expression was also found in the cerebral cortex and the amygdala of the experimental group. These characteristics were not observed in the control group. [Jpn J Physiol 54 Suppl:S196 (2004)]
