Systemically administered tempol reduces neuronal activity in paraventricular nucleus of hypothalamus and rostral ventrolateral medulla in rats

Content Provider	Scilit
Author	Wei, Shunguang Zhang, Zhi-Hua Yu, Yang Felder, Robert B.
Copyright Year	2009
Description	Journal: Journal of Hypertension Objective Systemic administration of the superoxide scavenger tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl) reduces blood pressure (BP), heart rate (HR) and sympathetic nerve activity in normotensive and hypertensive animals. The global nature of the depressor response to tempol suggests an inhibitory influence on cardiovascular presympathetic regions of the brain. This study examined several possible mechanisms for such an effect. Methods and results In urethane anesthetized rats, as expected, intravenous tempol (120 μmol/kg) reduced mean arterial pressure, HR and renal sympathetic nerve activity (RSNA). Concomitant central neuronal recordings revealed reduced spontaneous discharge (spikes/s) of neurons in the paraventricular nucleus of hypothalamus (from 2.9 ± 0.4 to 0.8 ± 0.2) and the rostral ventrolateral medulla (RVLM; from 9.8 ± 0.5 to 7.2 ± 0.4), two cardiovascular and autonomic regions of the brain. Baroreceptor-denervated rats had exaggerated sympathetic and cardiovascular responses. Pretreatment with the hydroxyl radical scavenger dimethyl sulfoxide (intravenous) attenuated the tempol-induced decreases in BP, HR and RSNA, but the nitric oxide synthesis inhibitor NG-nitro-L-arginine methyl ester (intravenous or intracerebroventricular) had no effect. Conclusion These findings suggest that systemically administered tempol acts upon neurons in paraventricular nucleus and RVLM to reduce BP, HR and RSNA, perhaps by reducing the influence of reactive oxygen species in those regions. The arterial baroreflex modulates the depressor responses to tempol. These central mechanisms must be considered in interpreting data from studies using systemically administered tempol to assess the role of reactive oxygen species in cardiovascular regulation.
Related Links	http://europepmc.org/articles/pmc2867327?pdf=render https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2867327/pdf
Ending Page	550
Page Count	8
Starting Page	543
ISSN	02636352
e-ISSN	14735598
DOI	10.1097/hjh.0b013e3283200442
Journal	Journal of Hypertension
Issue Number	3
Volume Number	27
Language	English
Publisher	Ovid Technologies (Wolters Kluwer Health)
Publisher Date	2009-03-01
Access Restriction	Open
Subject Keyword	Journal: Journal of Hypertension Cardiovascular, Paraventricular Nucleus of Hypothalamus, Rostral Ventrolateral Medulla, Sympathetic Nervous System, Tempol
Content Type	Text
Resource Type	Article
Subject	Physiology Internal Medicine Cardiology and Cardiovascular Medicine