title: Ghrelin modulates sympathetic nervous system activity and stress response in lean and overweight men.
abstract: Ghrelin is a growth hormone-releasing peptide secreted by the stomach with potent effects on appetite. Experimental and clinical studies indicate that ghrelin also influences cardiovascular regulation and metabolic function and mediates behavioral responses to stress. We investigated the effects of ghrelin on blood pressure (BP), sympathetic nervous system activity, and mental stress responses in lean (n=13) and overweight or obese (n=13) individuals. Subjects received an intravenous infusion of human ghrelin (5 pmol/kg per minute for 1 hour) and saline in a randomized fashion. Ghrelin decreased systolic (-6 and -11 mm Hg) and diastolic BP (-8 mm Hg for both), increased muscle sympathetic nervous system activity (18±2 to 28±3 bursts per min, P<0.05 and from 21±2 to 32±3 bursts per min, P<0.001) in lean and overweight or obese subjects, respectively, without a significant change in heart rate, calf blood flow, or vascular resistance. Ghrelin induced a rise in plasma glucose concentration in lean individuals (P<0.05) and increased cortisol levels in both groups (P<0.05). Stress induced a significant change in mean BP (+22 and +27 mm Hg), heart rate (+36 and +29 bpm), and muscle sympathetic nervous system activity (+6.1±1.6 and +6.8±2.7 bursts per min) during saline infusion in lean and overweight or obese subjects, respectively. During ghrelin infusion, the changes in BP and muscle sympathetic nerve activity in response to stress were significantly reduced in both groups (P<0.05). In conclusion, ghrelin exerts unique effects in that it reduces BP and increases muscle sympathetic nervous system activity and blunts cardiovascular responses to mental stress. These responses may represent a combination of peripheral (baroreflex-mediated) and central effects of ghrelin.
authors.affiliation: Human Neurotransmitters Laboratory, Baker IDI Heart & Diabetes Institute, PO Box 6492, St Kilda Road Central, Melbourne, Victoria 8008, Australia. Elisabeth.lambert@bakeridi.edu.au
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Lambert
authors.forename: Gavin
authors.initials: G
authors.lastname: Lambert
authors.forename: Carolina
authors.initials: C
authors.lastname: Ika-Sari
authors.forename: Tye
authors.initials: T
authors.lastname: Dawood
authors.forename: Katie
authors.initials: K
authors.lastname: Lee
authors.forename: Reena
authors.initials: R
authors.lastname: Chopra
authors.forename: Nora
authors.initials: N
authors.lastname: Straznicky
authors.forename: Nina
authors.initials: N
authors.lastname: Eikelis
authors.forename: Sara
authors.initials: S
authors.lastname: Drew
authors.forename: Alan
authors.initials: A
authors.lastname: Tilbrook
authors.forename: John
authors.initials: J
authors.lastname: Dixon
authors.forename: Murray
authors.initials: M
authors.lastname: Esler
authors.forename: Markus P
authors.initials: MP
authors.lastname: Schlaich
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects*; D005500:Follow-Up Studies; D054439:Ghrelin / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D050177:Overweight / Q000150:complications / Q000503:physiopathology*; D013315:Stress, Psychological / Q000150:complications / Q000503:physiopathology / Q000517:prevention & control*; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000503:physiopathology; D013851:Thinness / Q000150:complications / Q000503:physiopathology*; D014655:Vascular Resistance / Q000187:drug effects*; D055815:Young Adult
chemical_list: D054439:Ghrelin