title: Microinjection of salusin-beta into the nucleus tractus solitarii inhibits cardiovascular function by suppressing presympathetic neurons in rostral ventrolateral medulla in rats.
abstract: Salusin-beta is newly identified bioactive peptide of 20 amino acids, which is widely distributed in hematopoietic system, endocrine system, and the central nervous system (CNS). Although salusin-beta extensively expressed in the CNS, the central cardiovascular functions of salusin-beta are unclear. Our main objective was to determine the cardiovascular effect of microinjection of salusin-beta into the nucleus tractus solitarii (NTS) in anesthetized rats. Bilateral or unilateral microinjection of salusin-beta (0.94-94 microg/rat) into the NTS dose-dependently decreased blood pressure and heart rate. Bilateral NTS microinjection of salusin-beta (9.4 microg/rat) did not alter baroreflex sensitivity. Prior application of the glutamate receptor antagonist kynurenic acid (0.19 microg/rat, n=9) into the NTS did not alter the salusin-beta (9.4 microg/rat) induced hypotension and bradycardia. However, pretreatment with the GABA receptor agonist muscimol (0.5 ng/rat) within the rostral ventrolateral medulla (RVLM) completely abolished the hypotension (-14+/-5 vs. -3+/-5 mm Hg, P<0.05) and bradycardia (-22+/-6 vs. -6+/-5 bpm, P<0.05) evoked by intra-NTS salusin-beta (9.4 microg/rat). In addition, we found that vagotomy didn't influence the actions of salusin-beta (9.4 microg/rat) in the NTS. In conclusion, our present study shows that microinjection of salusin-beta into the NTS significantly produces hypotension and bradycardia, presumably by suppressing the activities of presympathetic neurons in the RVLM.
authors.affiliation: Department of Clinical Laboratory, San Ai Tang Hospital, Lanzhou, PR China. lu73free@gmail.com; Department of Physiology and Key Lab of Ministry of Education in Fertility Preservation and Maintenance, Ningxia Medical University, Yinchuan, PR China. yuanwj@hotmail.com.
authors.forename: Y
authors.initials: Y
authors.lastname: Lu
authors.forename: Y S
authors.initials: YS
authors.lastname: Wu
authors.forename: D S
authors.initials: DS
authors.lastname: Chen
authors.forename: M M
authors.initials: MM
authors.lastname: Wang
authors.forename: W Z
authors.initials: WZ
authors.lastname: Wang
authors.forename: W J
authors.initials: WJ
authors.lastname: Yuan
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000187:drug effects; D001919:Bradycardia / Q000139:chemically induced / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects*; D007022:Hypotension / Q000139:chemically induced / Q000503:physiopathology; D036341:Intercellular Signaling Peptides and Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D007736:Kynurenic Acid / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects*; D008845:Microinjections; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000187:drug effects*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D036341:Intercellular Signaling Peptides and Proteins; C528274:salusin-beta, rat; D009118:Muscimol; D007736:Kynurenic Acid