scholarly journals Elevated Oxidative Stress and Inflammation in Hypothalamic Paraventricular Nucleus Are Associated With Sympathetic Excitation and Hypertension in Rats Exposed to Chronic Intermittent Hypoxia

2018 ◽  
Vol 9 ◽  
Author(s):  
Tiejun Li ◽  
Yanli Chen ◽  
Chaojun Gua ◽  
Baogang Wu
Keyword(s):  
Oxidative Stress ◽  
Paraventricular Nucleus ◽  
Intermittent Hypoxia ◽  
Hypothalamic Paraventricular Nucleus ◽  
Chronic Intermittent Hypoxia

scholarly journals Chronic intermittent hypoxia increases sympathetic control of blood pressure: role of neuronal activity in the hypothalamic paraventricular nucleus

2013 ◽  
Vol 305 (12) ◽  
pp. H1772-H1780 ◽  
Author(s):  
Amanda L. Sharpe ◽  
Alfredo S. Calderon ◽  
Mary Ann Andrade ◽  
J. Thomas Cunningham ◽  
Steven W. Mifflin ◽  
...  
Keyword(s):  
Sleep Apnea ◽  
Neuronal Activity ◽  
Paraventricular Nucleus ◽  
Intermittent Hypoxia ◽  
Body Fluid ◽  
Early Stage ◽  
Brain Regions ◽  
Hypothalamic Paraventricular Nucleus ◽  
Chronic Intermittent Hypoxia ◽  
Increased Sensitivity

Like humans with sleep apnea, rats exposed to chronic intermittent hypoxia (CIH) experience arterial hypoxemias and develop hypertension characterized by exaggerated sympathetic nerve activity (SNA). To gain insights into the poorly understood mechanisms that initiate sleep apnea/CIH-associated hypertension, experiments were performed in rats exposed to CIH for only 7 days. Compared with sham-treated normoxic control rats, CIH-exposed rats ( n = 8 rats/group) had significantly increased hematocrit ( P < 0.001) and mean arterial pressure (MAP; P < 0.05). Blockade of ganglionic transmission caused a significantly ( P < 0.05) greater reduction of MAP in rats exposed to CIH than control rats ( n = 8 rats/group), indicating a greater contribution of SNA in the support of MAP even at this early stage of CIH hypertension. Chemical inhibition of neuronal discharge in the hypothalamic paraventricular nucleus (PVN) (100 pmol muscimol) had no effect on renal SNA but reduced lumbar SNA ( P < 0.005) and MAP ( P < 0.05) more in CIH-exposed rats ( n = 8) than control rats ( n = 7), indicating that CIH increased the contribution of PVN neuronal activity in the support of lumbar SNA and MAP. Because CIH activates brain regions controlling body fluid homeostasis, the effects of internal carotid artery injection of hypertonic saline were tested and determined to increase lumbar SNA more ( P < 0.05) in CIH-exposed rats than in control rats ( n = 9 rats/group). We conclude that neurogenic mechanisms are activated early in the development of CIH hypertension such that elevated MAP relies on increased sympathetic tonus and ongoing PVN neuronal activity. The increased sensitivity of Na+/osmosensitive circuitry in CIH-exposed rats suggests that early neuroadaptive responses among body fluid regulatory neurons could contribute to the initiation of CIH hypertension.

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