抄録
Ventilation changes depending on circadian light-dark cycle. Histaminergic neurons are involved in the circadian regulation in the brain, but a role of circadian pattern of ventilation is unknown. We examined ventilation and metabolism for 24 h in histamine type 1 receptor knockout (H1RKO) and wild-type mice. Mice were measured for ventilation by a whole-body plethysmograph and metabolism by a magnetic-type mass spectrometry, and consciousness was characterized by electroencephalogram. In both genotypes, minute ventilation (VE) and metabolic rate were greater during the dark period (20:00 to 8:00) than during the light period (8:00 to 20:00). H1RKO mice during the light period were greater in VE with increased tidal volume and greater in VCO2 without changes in VO2 than wild-type mice. The increased VE during the light period was responsible for the increased CO2 production with an identical ratio of VE to VCO2. However, H1RKO mice decreased the ratio compared to that of wild-type mice during the dark period, which was responsible for an increase of delta/theta ratio calculated from power spectrum density of electroencephalogram. Thus, deletion of H1 receptor affects patterns of ventilation accompanied with changes in metabolic substrates and arousal state of the dark period. Results suggest that histamine modulates ventilatory pattern during the light and the dark periods via H1 receptors. [J Physiol Sci. 2006;56 Suppl:S139]
