Neural responses to intravenous serotonin revealed by functional magnetic resonance imaging

• Published in: Journal of applied physiology (1985) 2002-01, Vol.92 (1), p.331-342
• Main Authors: Henderson, Luke A, Yu, Pearl L, Frysinger, Robert C, Galons, Jean-Philippe, Bandler, Richard, Harper, Ronald M
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Blood Pressure - drug effects; Brain - anatomy & histology; Brain - drug effects; Cardiac arrhythmia; Cardiovascular System - innervation; Cats; Echo-Planar Imaging; Electrocardiography; Female; Fundamental and applied biological sciences. Psychology; Heart; Heart attacks; Heart Rate - drug effects; Image Processing, Computer-Assisted; Injections, Intravenous; Lung - innervation; Magnetic Resonance Imaging; Male; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Neurology; Neurons - drug effects; Neurons, Afferent - drug effects; NMR; Nuclear magnetic resonance; Respiratory Mechanics - drug effects; Serotonin - administration & dosage; Serotonin - pharmacology; Time Factors; Vertebrates: nervous system and sense organs
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2002.92.1.331

1  Department of Neurobiology, University of California at Los Angeles, California 90095-1763; 2  Department of Anatomy and Histology and Pain Management and Research Center, Royal North Shore Hospital, University of Sydney, Sydney, New South Wales 2006, Australia; and 3  Department of Radiology, University of Arizona, Tucson, Arizona 85724 We examined the sequence of neural responses to the hypotension, bradycardia, and apnea evoked by intravenous administration of 5-hydroxytryptamine (serotonin). Functional magnetic resonance imaging signal changes were assessed in nine isoflurane-anesthetized cats during baseline and after a bolus intravenous low dose (10   µg/kg) or high dose (20-30 µg/kg) of 5-hydroxytryptamine. In all cats, high-dose challenges elicited rapid-onset, transient signal declines in the intermediate portion of the solitary tract nucleus, caudal midline and caudal and rostral ventrolateral medulla, and fastigial nucleus of the cerebellum. Slightly delayed phasic declines appeared in the dentate and interpositus nuclei and dorsolateral pons. Late-developing responses also emerged in the solitary tract nucleus, parapyramidal region, periaqueductal gray, spinal trigeminal nucleus, inferior olivary nucleus, cerebellar vermis, and fastigial nucleus. Amygdala and hypothalamic sites showed delayed and prolonged signal increases. Intravenous serotonin infusion recruits cerebellar, amygdala, and hypothalamic sites in addition to classic brain stem cardiopulmonary areas and exhibits site-specific temporal patterns. myocardial ischemia; Bezold-Jarisch reflex; bradycardia; apnea; hypotension