Effects of corticotropin-releasing factor on central respiratory activity

Effects of corticotropin-releasing factor (CRF) on central regulation of respiration were studied in urethane-anaesthetized, vagotomized, paralyzed and artificially ventilated rabbits. Injections of CRF into the IVth cerebral ventrile (i.c.v.) resulted in an increase of the neuronal tidal volume (nVt), but had only minor effects on the duration of respiratory phases. Microinjection of CRF into the ventral parabrachial region of the pons (pneumotaxic center) resulted in a reduction of nVt and of the respiration rate. Respiratory effects of CRF administered i.c.v. or into the pontine parabrachial region were antagonized by alpha-helical-CRF, indicating a receptor-mediated action of CRF. Respiratory effects of CRF were not significantly affected after blocking ganglionic transmission with chlorisondamine. Neither mean arterial blood pressure nor heart rate were significantly affected by the injection of CRF into the IVth ventricle or the rostral pons. Results suggest an involvement of CRF in the central regulation of respiratory movements. CRF may be involved in the adaptation of respiration to stress.