Neural responses to intravenous serotonin revealed by functional magnetic resonance imaging.
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 microg/kg) or high dose (20-30 microg/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.
Henderson
Luke A
LA
Department of Neurobiology, University of California at Los Angeles, California 90095-1763, USA.
Yu
Pearl L
PL
Frysinger
Robert C
RC
Galons
Jean-Philippe
JP
Bandler
Richard
R
Harper
Ronald M
RM
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000033:anatomy & histology / Q000187:drug effects*; D002319:Cardiovascular System / Q000294:innervation; D002415:Cats; D017352:Echo-Planar Imaging; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D007091:Image Processing, Computer-Assisted; D007275:Injections, Intravenous; D008168:Lung / Q000294:innervation; D008279:Magnetic Resonance Imaging; D008297:Male; D009474:Neurons / Q000187:drug effects*; D009475:Neurons, Afferent / Q000187:drug effects; D015656:Respiratory Mechanics / Q000187:drug effects; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
D012701:Serotonin