Role of the sympathetic nervous system in cerebrovascular responses to air-jet stress in rats

• Published in: Stress (Amsterdam, Netherlands) Vol. 15; no. 1; pp. 115 - 120
• Main Authors: Revel, Aurélia, Oréa, Valérie, Chapuis, Bruno, Barrès, Christian, Julien, Claude
• Format: Journal Article
• Language: English
• Published: England Informa Healthcare 01.01.2012; Taylor & Francis
• Subjects: Adrenergic beta-2 Receptor Antagonists - pharmacology; Air-jet stress; Animals; Blood Flow Velocity - physiology; Blood Pressure; carotid blood flow; carotid vascular conductance; Cerebrovascular Circulation - drug effects; Cerebrovascular Circulation - physiology; Laser-Doppler Flowmetry; Male; Propanolamines - pharmacology; Rats; Rats, Sprague-Dawley; Stress, Psychological - physiopathology; stroke; superior cervical ganglion; Superior Cervical Ganglion - physiology; sympathetic nervous system; Sympathetic Nervous System - physiology; Vasoconstriction
• ISSN: 1025-3890; 1607-8888; 1607-8888
• DOI: 10.3109/10253890.2011.597901

This study examined the role of sympathetic nerves in the control of cerebral hemodynamics during air-jet stress. In adult male Sprague-Dawley rats, blood flow velocity (pulsed Doppler) was measured in both internal carotid arteries 1 week after excision of one superior cervical ganglion. Blood pressure (BP) and carotid blood flows (CBFs) were simultaneously recorded during exposure to air-jet stress. In 5 out of 13 rats, stress was applied after β2-adrenoceptor blockade with ICI 118551 (0.4 mg/kg, then 0.2 mg/kg/h, i.v). Stress evoked an immediate rise in BP, CBFs, and vascular conductances. Vasodilatation was much larger on the denervated side than on the intact side (mean ± SEM: 78 ± 7 versus 19 ± 4%; P < 0.02) and lasted about 10 s. Thereafter, blood flows returned to or near normal and showed parallel variations while BP remained elevated. There was, therefore, a net vasoconstriction on both sides. In ICI 118551-treated rats, the initial vasodilatation was not significantly reduced on the denervated side (64 ± 4%), but the subsequent vasoconstriction was enhanced (P < 0.05) on both sides. In conclusion, air-jet stress evokes an immediate, short-lasting vasodilatation through a mechanism unrelated to β2-adrenoceptor stimulation. Sympathetic nerves powerfully limit this phenomenon, and thus contribute to protect the cerebral circulation from stress-induced BP surges.