Suppression of the late component of the carotid occlusion reflex by lesion of the medial forebrain bundle in the rat.
1. The pressor response to a prolonged carotid occlusion in the rat has two components: an early, fast increase in blood pressure, and a late, slow and sustained hypertension. Since the second component can be blocked by a disconnecting lesion near the medial side of the medial forebrain bundle, the hypothesis that this complex structure is involved in the integration of the late pressor reflex was tested. 2. The medial forebrain bundle was partially or completely destroyed, or a disconnecting lesion was made to interrupt some of its medially running afferents and/or efferents. Incomplete lesion caused a transient suppression of the second component in 4 rats, whereas complete lesion in 5 rats or probable interruption of the medial efferent pathways in 3 rats led to suppression of the late component when the one-minute occlusion was performed within one hour after the lesion. 3. The data show that the medial forebrain bundle plays an important role in the integration of the late component of the pressor response to prolonged carotid occlusion.
D000818:Animals; D001794:Blood Pressure; D002339:Carotid Arteries / Q000502:physiology*; D007033:Hypothalamus, Middle / Q000502:physiology; D008297:Male; D008474:Medial Forebrain Bundle / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology*; D011311:Pressoreceptors / Q000503:physiopathology*; D051381:Rats