Hypothalamic administration of sargahydroquinoic acid elevates peripheral thermogenic signaling and ameliorates high fat diet-induced obesity through the sympathetic nervous system.

Sargassum serratifolium (C. Agardh) C.Agardh, a marine brown alga, has been consumed as a food and traditional medicine in Asia. A previous study showed that the meroterpenoid-rich fraction of an ethanolic extract of S. serratifolium (MES) induced adipose tissue browning and suppressed diet-induced obesity and metabolic syndrome when orally supplemented. Sargahydroquinoic acid (SHQA) is a major component of MES. However, it is unclear whether SHQA regulates energy homeostasis through the central nervous system. To examine this, SHQA was administrated through the third ventricle in the hypothalamus in high-fat diet-fed C57BL/6 mice and investigated its effects on energy homeostasis. Chronic administration of SHQA into the brain reduced body weight without a change in food intake and improved metabolic syndrome-related phenotypes. Cold experiments and biochemical analyses indicated that SHQA elevated thermogenic signaling pathways, as evidenced by an increase in body temperature and UCP1 signaling in white and brown adipose tissues. Peripheral denervation experiments using 6-OHDA indicated that the SHQA-induced anti-obesity effect is mediated by the activation of the sympathetic nervous system, possibly by regulating genes associated with sympathetic outflow and GABA signaling pathways. In conclusion, hypothalamic injection of SHQA elevates peripheral thermogenic signaling and ameliorates diet-induced obesity.

Comparison of Resveratrol Supplementation and Energy Restriction Effects on Sympathetic Nervous System Activity and Vascular Reactivity: A Randomized Clinical Trial.

Background: Chronic sympathetic nervous system activation is associated with endothelial dysfunction and cardiometabolic disease, which may be modulated by resveratrol (RSV) and energy restriction (ER). This study aimed to examine the effects of RSV and ER on plasma noradrenaline (NA), flow-mediated vasodilation (ed-FMD), and endothelium-independent nitrate-mediated vasodilation (ei-NMD). Methods: The study included 48 healthy adults randomized to 30-days intervention of RSV or ER. Results: Waist circumference, total cholesterol, HDL-c, LDL-c, apoA-I, and plasma NA decreased in the ER group, whilst RSV increased apoB and total cholesterol, without changing plasma NA. No effects on vascular reactivity were observed in both groups. Plasma NA change was positively correlated with total cholesterol (r = 0.443; p = 0.002), triglycerides (r = 0.438; p = 0.002), apoA-I (r = 0.467; p = 0.001), apoB (r = 0.318; p = 0.032) changes, and ei-NMD (OR = 1.294; 95%CI: 1.021-1.640). Conclusions: RSV does not improve cardiometabolic risk factors, sympathetic activity, and endothelial function. ER decreases plasma NA and waist circumference as well as improves blood lipids, but does not modify endothelial function. Finally, plasma NA was associated with ei-NMD, which could be attributed to a higher response to nitrate in patients with greater resting sympathetic vasoconstriction.

Distribution of the Noradrenaline Innervation and Adrenoceptors in the Macaque Monkey Thalamus.

Noradrenaline (NA) in the thalamus has important roles in physiological, pharmacological, and pathological neuromodulation. In this work, a complete characterization of NA axons and Alpha adrenoceptors distributions is provided. NA axons, revealed by immunohistochemistry against the synthesizing enzyme and the NA transporter, are present in all thalamic nuclei. The most densely innervated ones are the midline nuclei, intralaminar nuclei (paracentral and parafascicular), and the medial sector of the mediodorsal nucleus (MDm). The ventral motor nuclei and most somatosensory relay nuclei receive a moderate NA innervation. The pulvinar complex receives a heterogeneous innervation. The lateral geniculate nucleus (GL) has the lowest NA innervation. Alpha adrenoceptors were analyzed by in vitro quantitative autoradiography. Alpha-1 receptor densities are higher than Alpha-2 densities. Overall, axonal densities and Alpha adrenoceptor densities coincide; although some mismatches were identified. The nuclei with the highest Alpha-1 values are MDm, the parvocellular part of the ventral posterior medial nucleus, medial pulvinar, and midline nuclei. The nucleus with the lowest Alpha-1 receptor density is GL. Alpha-2 receptor densities are highest in the lateral dorsal, centromedian, medial and inferior pulvinar, and midline nuclei. These results suggest a role for NA in modulating thalamic involvement in consciousness, limbic, cognitive, and executive functions.

Increase in diastolic blood pressure induced by fragrance inhalation of grapefruit essential oil is positively correlated with muscle sympathetic nerve activity.

Fragrance inhalation of essential oils is widely used in aromatherapy, and it is known to affect blood pressure (BP) and heart rate (HR) via autonomic control of circulation. In this study, we aimed to test the hypothesis that the changes in hemodynamics with fragrance inhalation were observed along with changes in muscle sympathetic nerve activity (MSNA). In study 1, thirteen healthy men were exposed to fragrance stimulation of grapefruit essential oil for 10 min, and BP, HR, and MSNA were continuously measured. In study 2, another nine healthy men were exposed to the same fragrance stimulation; responses in BP and HR were continuously measured, and plasma noradrenaline and cortisol concentrations were determined. We found that diastolic BP increased significantly during fragrance inhalation, while the other variables remained unchanged in both studies. Although MSNA burst frequency, burst incidence, and total activity remained unchanged during fragrance inhalation, we found a significant linear correlation between changes in diastolic BP in the last 5 min of fragrance inhalation and changes in MSNA burst frequency. The plasma cortisol concentration decreased significantly at 10 min of fragrance inhalation, though the noradrenaline concentration remained unchanged. These results suggest, for the first time, that changes in BP with fragrance inhalation of essential oil are associated with changes in MSNA even with decreased stress hormone.

Evaluation of effect of Acacia jacquemontii Benth. on blood pressure in normotensive and fructose induced hypertensive sprague dawley rats: An ethnopharmacological approach.

Acacia jacquemontii Benth. is used traditionally to treat hypertension but no scientific literature supports this claim. So, this study was aimed at validating this claim. This was done by injecting various doses of crude extract of Acacia jacquemontii, AJC (5, 10, 20, 30mg/kg) and all fractions (hexane, ethyl acetate, n-butanol and aqueous) (3, 5, 10, 20mg/kg) intravenously in anaesthetized rat. Based on the results, butanol fraction (AJB) at 20mg/kg was found to be the most potent, so it was selected for exploring mechanisms of action. For this purpose, different groups were injected with various pharmacological inhibitors (L-NAME, atropine, captopril, propranolol and hexamethonium) prior to AJB administration. Also, AJB at 20mg/kg was evaluated for prolonged hypotensive effect for the period of 40 min. Results showed a significant dose dependent reduction in BP in normotensive and in hypertensive rats. AJC and AJB produced a decline in SBP, DBP and MAP with p<0.05 - p<0.001 and p<0.001 respectively in normotensive animals. Whereas in hypertensive animals, AJC showed significant reduction at 5mg/kg with p<0.01 and at 10, 20 and 30 mg/kg with p<0.001. AJB produced a decline in hypertensive animals at all tested doses with p<0.001. AJB resulted in hypotensive effect mediated by ß receptors, ganglionic block operating central sympathetic neural responses and renin angiotensin aldosterone system (RAAS). This study supports the ethnomedicinal claim of Acacia jacquemontii Benth. in treating hypertension.

Systemic serotonin inhibits brown adipose tissue sympathetic nerve activity via a GABA input to the dorsomedial hypothalamus, not via 5HT1A receptor activation in raphe pallidus.

AIM: Serotonin (5-hydroxytryptamine, 5-HT), an important neurotransmitter and hormone, modulates many physiological functions including body temperature. We investigated neural mechanisms involved in the inhibition of brown adipose tissue (BAT) sympathetic nerve activity (SNA) and BAT thermogenesis evoked by 5-HT. METHODS: Electrophysiological recordings, intravenous (iv) injections and nanoinjections in the brains of anaesthetized rats. RESULTS: Cooling-evoked increases in BAT SNA were inhibited by the intra-rostral raphé pallidus (rRPa) and the iv administration of the 5-HT1A receptor agonist, 8-OH-DPAT or 5-HT. The intra-rRPa 5-HT, the intra-rRPa and the iv 8-OH-DPAT, but not the iv 5-HT-induced inhibition of BAT SNA were prevented by nanoinjection of a 5-HT1A receptor antagonist in the rRPa. The increase in BAT SNA evoked by nanoinjection of NMDA in the rRPa was not inhibited by iv 5-HT, indicating that iv 5-HT does not inhibit BAT SNA by acting in the rRPa or in the sympathetic pathway distal to the rRPa. In contrast, under a warm condition, blockade of 5HT1A receptors in the rRPa increased BAT SNA and BAT thermogenesis, suggesting that endogenous 5-HT in the rRPa contributes to the suppression of BAT SNA and BAT thermogenesis. The increases in BAT SNA and BAT thermogenesis evoked by nanoinjection of NMDA in the dorsomedial hypothalamus (DMH) were inhibited by iv 5-HT, but those following bicuculline nanoinjection in the DMH were not inhibited. CONCLUSIONS: The systemic 5-HT-induced inhibition of BAT SNA requires a GABAergic inhibition of BAT sympathoexcitatory neurones in the DMH. In addition, during warming, 5-HT released endogenously in rRPa inhibits BAT SNA.

Antihypertensive and Renoprotective Effects of Dietary Flaxseed and its Mechanism of Action in Deoxycorticosterone Acetate-Salt Hypertensive Rats.

BACKGROUND/AIMS: Flaxseed contains alpha-linolenic acid (ALA), lignans, and dietary fiber, and its intake lowers blood pressure in hypertensive patients. Here, we examined the effects of flaxseed powder, which includes all flaxseed components, flaxseed oil, composed mainly of ALA, flaxseed lignan, and flaxseed fiber, on hypertension and renal damage induced by deoxycorticosterone acetate (DOCA)-salt. Then, we investigated the mechanisms of action associated with the effects of flaxseed. METHODS: Flaxseed powder, oil, lignan, or fiber was administered to DOCA-salt rats. Systolic blood pressure (SBP), urinary protein excretion, renal angiotensin converting enzyme (ACE) activity, sympathetic nerve activity, and gene expression of inflammatory mediators in the kidney and hypothalamus were measured. RESULTS: Flaxseed powder and oil reduced the increases in SBP and urinary protein excretion induced by DOCA-salt treatment, whereas lignan and fiber had no effects. Flaxseed oil suppressed the increase in renal ACE activity, sympathetic nerve activity, and gene expression of renal and hypothalamic inflammatory mediators. CONCLUSION: Flaxseed has antihypertensive and renoprotective effects in DOCA-salt rats. These effects are likely principally exerted by ALA. Furthermore, the suppression of renal ACE activity, sympathetic nerve activity, and inflammation is partly involved in the effects of flaxseed.

Effect of Salt Supplementation on Sympathetic Activity and Endothelial Function in Salt-Sensitive Type 2 Diabetes.

CONTEXT: Lower sodium intake is paradoxically associated with higher mortality in type 2 diabetes (T2D). OBJECTIVE: To determine whether sympathetic nervous system (SNS) activation and endothelial dysfunction contribute to these observations, we examined the effect of salt supplementation on these systems in people with T2D with habitual low sodium. We hypothesized that salt supplementation would lower SNS activity and improve endothelial function compared to placebo. DESIGN: We conducted a randomized, double-blinded, placebo-controlled crossover trial. SETTING: The study took place in a tertiary referral diabetes outpatient clinic. PARTICIPANTS: Twenty-two people with T2D with habitual low sodium intake (24-hour urine sodium <150 mmol/24h) were included. INTERVENTION: Salt supplementation (100 mmol NaCl/24h) or placebo for 3 weeks was administered. MAIN OUTCOME MEASURES: The primary outcome of SNS activity and endothelial function was assessed as follows: Microneurography assessed muscle sympathetic nerve activity (MSNA), pulse amplitude tonometry assessed endothelial function via reactive hyperemic index (RHI), and arterial stiffness was assessed via augmentation index (AI). Secondary outcomes included cardiac baroreflex, serum aldosterone, ambulatory blood pressure monitoring (ABPM), heart rate variability (HRV), and salt sensitivity. RESULTS: Compared to placebo, salt supplementation increased MSNA (burst frequency P = .047, burst incidence P = .016); however, RHI (P = .24), AI (P = .201), ABPM (systolic P = .09, diastolic P = .14), and HRV were unaffected. Salt supplementation improved baroreflex (slope P = .026) and lowered aldosterone (P = .004), and in salt-resistant individuals there was a trend toward improved RHI (P = .07). CONCLUSIONS: In people with T2D and low habitual sodium intake, salt supplementation increased SNS activity without altering endothelial function or blood pressure but improved baroreflex function, a predictor of cardiac mortality. Salt-resistant individuals trended toward improved endothelial function with salt supplementation.

Melatonin attenuates renal sympathetic overactivity and reactive oxygen species in the brain in neurogenic hypertension.

Sympathetic overactivation contributes to the pathogenesis of both experimental and human hypertension. We have previously reported that oxidative stress in sympathetic premotor neurons leads to arterial baroreflex dysfunction and increased sympathetic drive to the kidneys in an experimental model of neurogenic hypertension. In this study, we hypothesized that melatonin, a potent antioxidant, may be protective in the brainstem regions involved in the tonic and reflex control of blood pressure (BP) in renovascular hypertensive rats. Neurogenic hypertension was induced by placing a silver clip (gap of 0.2 mm) around the left renal artery, and after 5 weeks of renal clip placement, the rats were treated orally with melatonin (30 mg/kg/day) by gavage for 15 days. At the end of melatonin treatment, we evaluated baseline mean arterial pressure (MAP), renal sympathetic nerve activity (rSNA), and the baroreflex control of heart rate (HR) and rSNA. Reactive oxygen species (ROS) were detected within the brainstem regions by dihydroethidium staining. Melatonin treatment effectively reduced baseline MAP and sympathoexcitation to the ischemic kidney in renovascular hypertensive rats. The baroreflex control of HR and rSNA were improved after melatonin treatment in the hypertensive group. Moreover, there was a preferential decrease in ROS within the rostral ventrolateral medulla (RVLM) and the nucleus of the solitary tract (NTS). Therefore, our study indicates that melatonin is effective in reducing renal sympathetic overactivity associated with decreased ROS in brainstem regions that regulate BP in an experimental model of neurogenic hypertension.

Renal denervation ameliorates post-infarction cardiac remodeling in rats through dual regulation of oxidative stress in the heart and brain.

BACKGROUND: Myocardial remodeling is the key step in the development of ischemic cardiomyopathy. We aimed to compare effects of renal denervation (RDN) with those of angiotensin receptor neprilysin inhibitors (ARNi) on cardiac remodeling after myocardial infarction (MI), and explore underlying mechanism. METHODS: Sprague-Dawley rats (n = 40; male) were subjected to ligation of left anterior descending coronary artery to induce MI; six rats served as controls. ARNi was administered at a dose of 60 mg/kg/day for 4 weeks starting 1 week after MI. An RDN/Sham-RDN procedure was performed 1 week after MI. Rats in all groups were studied 5 weeks after MI. Echocardiography was used to evaluate cardiac function. Masson staining and TUNEL staining were used to determine the extent of cardiac remodeling. Indicators of oxidative stress in heart and brain were used to analyze the potential mechanisms involved. RESULTS: Five weeks after MI, both RDN and ARNi significantly improved cardiac function and cardiac remodeling; however, RDN was superior to ARNi at attenuating myocardial apoptosis. Compared to ARNi, RDN was also more effective at decreasing the abnormal oxidative stress caused by MI; this was especially true in case of the brain and was confirmed by evaluating the changes in reactive oxygen species (ROS) levels and other oxidative stress parameters following MI. CONCLUSIONS: RDN is not inferior to ARNi with respect to the improvement of cardiac remodeling in rats with ischemic cardiomyopathy. The effect of RDN might be associated with effective inhibition of oxidative stress in both the heart and brain.

A Fragrant Environment Containing α-Pinene Suppresses Tumor Growth in Mice by Modulating the Hypothalamus/Sympathetic Nerve/Leptin Axis and Immune System.

The environment is thought to affect outcomes in patients with cancer; however, this relationship has not been proven directly. Recently, an enriched environment, as a model of a positive environment, has been shown to suppress tumor growth by lowering leptin production through a pathway involving the hypothalamus/sympathetic nerve/leptin axis. We previously reported that a fragrant environment (FE) containing α-pinene suppressed tumor growth in mice; however, the underlying mechanism has not been elucidated. Accordingly, in this study, we investigated changes in the neuroendocrine and immune systems following exposure to an FE. Mice were exposed to α-pinene (5 h/day) for 4 weeks prior to tumor implantation with murine melanoma cells and 3 weeks after transplantation. In addition to the evaluation of tumor growth, the blood, spleen, and hypothalamus were collected 3 weeks after transplantation, and neuroendocrinological and immunological parameters were measured. Tumor size was ~40% smaller in mice exposed to FE. Moreover, plasma noradrenaline concentrations, which reflected sympathetic nervous activity, tended to increase, and leptin levels were significantly decreased in FE-exposed mice. Levels of stress hormones, such as plasma corticosterone and adrenaline, did not change in the 2 groups. In the hypothalamus, brain-derived neurotrophic factor protein levels and glucose-1-phosphate concentrations were decreased in the FE group. Additionally, numbers of B cells, CD4+ T cells, CD8+ T cells, and natural killer cells increased in the FE-exposed mice. These neurohormonal and immunological changes in the FE-exposed mice suggested that the FE may activate the hypothalamus/sympathetic nerve/leptin axis and immune system, thereby retarding tumor growth.

Impact of short-acting loop diuretic doses and cardiac sympathetic nerve abnormalities on outcomes of patients with reduced left ventricular function.

Recent studies reported that high doses of short-acting loop diuretics are associated with poor outcomes in patients with heart failure (HF). Short-acting loop diuretics have been shown to activate the renin-angiotensin system (RAS) and have no favorable effects on cardiac sympathetic nervous system (SNS) activity. The goal of this study is to investigate the relationship between daily doses of furosemide and the outcomes of patients with left ventricular dysfunction (LVD) from the viewpoint of cardiac SNS abnormalities using iodine-123-labeled metaiodobenzylguanidine (l-MIBG) myocardial scintigraphy.We enrolled 137 hospitalized patients (62.5 ±â€Š14.2 years old, 103 men) with LVEF < 45% who underwent l-MIBG myocardial scintigraphy. A delayed heart-to-mediastinum ratio (delayed HMR) was assessed using l-MIBG scintigraphy. Cardiac events were defined as cardiac death or re-hospitalization due to the deterioration of HF. Cox proportional hazard analysis was used to identify predictors of cardiac events.Cardiac events occurred in 57 patients in a follow-up period of 33.1 ±â€Š30 months. In a multivariate Cox proportional hazard analysis, delayed HMR and furosemide doses were identified as independent predictors of cardiac events (P = .0042, P = .033, respectively). Inverse probability of treatment weighting Cox modeling showed that the use of furosemide (≥40 mg /day) was associated with cardiac events with a hazard ratio of 1.96 (P = .003). In the Kaplan-Mayer analysis, the cardiac event-free survival rate was significantly lower in patients treated with high doses of furosemide (≥60 mg/day vs 40-60 mg/day vs <40 mg/day, the Log-rank test P < .0001). In a receiver-operating characteristic (ROC) analysis, the cut-off value for cardiac events was 40 mg/day of furosemide. The cardiac event-free rate was significantly lower in patients with delayed HMR <1.8 (median value) and receiving furosemide ≥40 mg/day than in other patients (the Log-rank test P < .0001). Significant differences in cardiac event rates according to furosemide doses among patients with delayed HMR <1.8 were observed among patients without ß-blocker therapy (P = .001), but not among those with ß-blocker therapy (P = .127).The present results indicate that a relationship exists between higher doses of furosemide and poor outcomes. The prognosis of HF patients with severe cardiac SNS abnormalities receiving high-dose short-acting loop diuretics is poor.

Chlorogenic acid-enriched green coffee bean extract affects arterial stiffness assessed by the cardio-ankle vascular index in healthy men: a pilot study.

The effect of chlorogenic acid-enriched green coffee bean extract (cGCE) intake on arterial stiffness was investigated using the cardio-ankle vascular index (CAVI) as a novel surrogate marker for predicting arteriosclerosis. A placebo-controlled double-blind pilot study was conducted with 16 healthy Japanese men. Subjects were divided into two groups and consumed beverages containing either cGCE or placebo daily for 2 weeks. The CAVI, the primary endpoint of the study, was evaluated at the beginning of the study and 2 weeks later. Endothelium-dependent flow-mediated dilation (FMD) and sympathetic nervous activity (SNA), which are thought to be related to the CAVI, were also measured. The CAVI change was significantly greater in the cGCE group than in the placebo group. In addition, FMD increased and SNA decreased in the cGCE group. These findings suggest that 2-week ingestion of cGCE may improve arterial stiffness as assessed by the CAVI.

Docosahexaenoic acid reduces resting blood pressure but increases muscle sympathetic outflow compared with eicosapentaenoic acid in healthy men and women.

Supplementation with monounsaturated or ω-3 polyunsaturated fatty acids ( n-3 PUFA) can lower resting blood pressure (BP) and reduce the risk of cardiovascular events. The independent contributions of the n-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on BP, and the mechanisms responsible, are unclear. We tested whether EPA, DHA, and olive oil (OO), a source of monounsaturated fat, differentially affect resting hemodynamics and muscle sympathetic nerve activity (MSNA). Eighty-six healthy young men and women were recruited to participate in a 12-wk, randomized, double-blind trial examining the effects of orally supplementing ~3 g/day of EPA ( n = 28), DHA ( n = 28), or OO ( n = 30) on resting hemodynamics; MSNA was examined in a subset of participants ( n = 31). Both EPA and DHA supplements increased the ω-3 index ( P < 0.01). Reductions in systolic BP were greater [adjusted intergroup mean difference (95% confidence interval)] after DHA [-3.4 mmHg (-0.9, -5.9), P = 0.008] and OO [-3.0 mmHg (-0.5, -5.4), P = 0.01] compared with EPA, with no difference between DHA and OO ( P = 0.74). Reductions in diastolic BP were greater following DHA [-3.4 mmHg (-1.3,-5.6), P = 0.002] and OO [-2.2 mmHg (0.08,-4.3), P = 0.04] compared with EPA. EPA increased heart rate compared with DHA [4.2 beats/min (-0.009, 8.4), P = 0.05] and OO [4.2 beats/min, (0.08, 8.3), P = 0.04]. MSNA burst frequency was higher after DHA [4 bursts/min (0.5, 8.3), P = 0.02] but not OO [-3 bursts/min (-6, 0.6), P = 0.2] compared with EPA. Overall, DHA and OO evoked similar responses in resting BP; however, DHA, but not OO, increased peripheral vasoconstrictor outflow. These findings may have implications for fatty acid supplementation in clinical populations characterized by chronic high BP and sympathetic overactivation. NEW & NOTEWORTHY We studied the effects of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and olive oil supplementation on blood pressure (BP) and muscle sympathetic nerve activity (MSNA). After 12 wk of 3 g/day supplementation, DHA and olive oil were associated with lower resting systolic and diastolic BPs than EPA. However, DHA increased MSNA compared with EPA. The reductions in BP with DHA likely occur via a vascular mechanism and evoke a baroreflex-mediated increase in sympathetic activity.

Aromatherapy: Activating olfactory calcium-sensing receptors impairs renal hemodynamics via sympathetic nerve-mediated vasoconstriction.

AIM: This study determines whether the activation of olfactory calcium-sensing receptor initiates a sympathetic activation-dependent neurovascular reflex subsequently contributing to renal hemodynamic depression. METHODS: Immunohistochemistry and nose-loading calcium-sensitive dye were used to explore the location and function of calcium-sensing receptor on the olfactory sensory neuron. The renal sympathetic nervous activity, renal hemodynamics and the microcirculation of kidney, liver and intestine were evaluated after liquid-phase intranasal administrations of saline, lidocaine, calcium-sensing receptor agonists and antagonist in sham and bilateral renal denervated rats. Real-time renal glomerular filtration rate was measured by a magnetic resonance renography. RESULTS: Calcium-sensing receptors were expressed on the cilia the olfactory sensory neuron and their activation depolarized olfactory sensory neuron and induced the calcium influx in the terminal side on olfactory glomeruli. Activating olfactory calcium-sensing receptors significantly increased arterial blood pressure and renal sympathetic nervous activities and subsequently decreased renal blood flow, renal, hepatic and enteral microcirculation. Cotreatments with calcium-sensing receptor antagonist or lidocaine inhibited these physiological alterations. The renal hemodynamic depressions by olfactory calcium-sensing receptor activation were significantly blocked by bilateral renal denervation. The intranasal manganese administration decreased the glomerular filtration rate. CONCLUSION: Calcium-sensing receptor acts as a functional chemosensory receptor on olfactory sensory neuron, and its activation causes the global sympathetic enhancement contributing to systematic vasoconstriction and subsequently depresses renal blood flow and glomerular filtration rate. These data implicate a possibly clinical aspect that several environmental stimuli may activate olfactory calcium-sensing receptors to evoke a sympathetic nervous system-mediated neurovascular reflex to depress renal hemodynamics.

Voluntary Corn Oil Ingestion Increases Energy Expenditure and Interscapular UCP1 Expression Through the Sympathetic Nerve in C57BL/6 Mice.

SCOPE: Previously, it has been found that corn oil ingestion activates both the gustatory system and brain reward system, stimulating motivation for eating. In the present study, the effect of voluntary corn oil ingestion on body weight gain and energy metabolism in mice is investigated. METHODS AND RESULTS: Voluntary corn oil ingestion with normal chow feeding does not lead to higher body weight than that of only the chow-fed control group. Mice that ingested corn oil have a higher total caloric intake and energy expenditure than did mice in the control group. Further, voluntary corn oil ingestion significantly upregulates Ucp1 mRNA and protein in interscapular brown adipose tissue (IBAT). Finally, the sympathetic nerve connected to IBAT was surgically transacted, then the body weight is measured for 8 weeks. IBAT sympathetic nerve transection surgery does not affect the body weight gain and food intake; however, when mice ingested corn oil, it induces significant body weight gain without changing the total caloric intake. IBAT sympathetic nerve transection surgery significantly suppresses UCP1 upregulation by corn oil ingestion. CONCLUSION: The present data suggest that corn oil ingestion activates IBAT through the sympathetic nerve, upregulating UCP1 expression and increasing energy expenditure.

Vagal Mediation of Low-Frequency Heart Rate Variability During Slow Yogic Breathing.

OBJECTIVE: Changes in heart rate variability (HRV) associated with breathing (respiratory sinus arrhythmia) are known to be parasympathetically (vagally) mediated when the breathing rate is within the typical frequency range (9-24 breaths per minute [bpm]; high-frequency HRV). Slow yogic breathing occurs at rates below this range and increases low-frequency HRV power, which may additionally reflect a significant sympathetic component. Yogic breathing techniques are hypothesized to confer health benefits by increasing cardiac vagal control, but increases in low-frequency HRV power cannot unambiguously distinguish sympathetic from parasympathetic contributions. The aim of this study was to investigate the autonomic origins of changes in low-frequency HRV power due to slow-paced breathing. METHODS: Six healthy young adults completed slow-paced breathing with a cadence derived from yogic breathing patterns. The paced breathing took place under conditions of sympathetic blockade, parasympathetic (vagal) blockade, and placebo. HRV spectral power was compared under 11 breathing rates during each session, in counterbalanced order with frequencies spanning the low-frequency range (4-9 bpm). RESULTS: HRV power across the low-frequency range (4-9 bpm) was nearly eliminated (p = .016) by parasympathetic blockade (mean (SD) spectral power at breathing frequency = 4.1 (2.1)) compared with placebo (69.5 (8.1)). In contrast, spectral power during sympathetic blockade 70.2 (9.1) and placebo (69.5 (8.1)) was statistically indistinguishable (p = .671). CONCLUSIONS: These findings clarify the interpretation of changes in HRV that occur during slow-paced breathing by showing that changes in low-frequency power under these conditions are almost entirely vagally mediated. Slow-paced breathing is an effective tool for cardiac vagal activation.

The involvement of sympathetic nervous system in essence of chicken-facilitated physiological adaption and circadian resetting.

AIM: The impact of the sympathetic nervous system (SNS) on the regulation of circadian rhythm and physiological functions is still not clear. Previous studies have found that essence of chicken (EC) supplementation facilitated the physiological adaption and circadian resetting in rats subjected to jet lag. Herein, the effects of SNS on the circadian clock and the hypothesis that EC-induced acceleration of circadian resetting is dependent on the SNS are investigated. MAIN METHODS: Male Wistar rats with superior cervical ganglionectomy (SCGx) were used to investigate the role of the SNS in circadian rhythm and physiological functions. SCGx rats were further fed with or without EC-containing diet for 2 weeks and subjected to artificial jet lag. KEY FINDINGS: Loss of SNS did not affect the circadian rhythm both in the hypothalamic suprachiasmatic nuclei (SCN) and peripheral clocks, including the liver and heart. The serum lipid levels were increased significantly in SCGx rats, together with the up-regulation of lipogenic gene expression in the liver and slight effect on serum hormones. The quicker resetting process of the clock genes in peripheral tissues of EC-fed rats was abolished after SCGx. In contrast, the phase shift of serum melatonin and corticosterone were faster in EC-fed rats, compared to that of control rats. SIGNIFICANCE: The SNS controls different aspects of physiological functions, and it has little effect on circadian system under normal light/dark condition. The effects EC on peripheral circadian synchrony and physiological functions were dependent on, at least partly, through the regulation of sympathetic nerve function.

Epac2a-knockout mice are resistant to dexamethasone-induced skeletal muscle atrophy and short-term cold stress.

Exchange protein directly activated by cAMP (Epac) 2a-knockout (KO) mice exhibit accelerated diet-induced obesity and are resistant to leptin-mediated adipostatic signaling from the hypothalamus to adipose tissue, with sustained food intake. However, the impact of Epac2a deficiency on hypothalamic regulation of sympathetic nervous activity (SNA) has not been elucidated. This study was performed to elucidate the response of Epac2a-KO mice to dexamethasone-induced muscle atrophy and acute cold stress. Compared to age-matched wild-type mice, Epac2a-KO mice showed higher energy expenditures and expression of myogenin and uncoupling protein-1 in skeletal muscle (SM) and brown adipose tissue (BAT), respectively. Epac2a-KO mice exhibited greater endurance to dexamethasone and cold stress. In wild-type mice, exogenous leptin mimicked the responses observed in Epac2a-KO mice. This suggests that leptin-mediated hypothalamic signaling toward SNA appears to be intact in these mice. Hence, the potentiated responses of SM and BAT may be due to their high plasma leptin levels. [BMB Reports 2018; 51(1): 39-44].

Taurine Supplementation Reduces Renal Nerve Activity in Male Rats in which Renal Nerve Activity was Increased by a High Sugar Diet.

This study tests the hypothesis that taurine supplementation reduces sugar-induced increases in renal sympathetic nerve activity related to renin release in adult male rats. After weaning, male rats were fed normal rat chow and drank water containing 5% glucose (CG) or water alone (CW) throughout the experiment. At 6-7 weeks of age, each group was supplemented with or without 3% taurine in drinking water until the end of experiment. At 7-8 weeks of age, blood chemistry and renal nerve activity were measured in anesthetized rats. Body weights slightly and significantly increased in CG compared to CW groups but were not significantly affected by taurine supplementation. Plasma electrolytes except bicarbonate, plasma creatinine, and blood urea nitrogen were not significantly different among the four groups. Mean arterial pressure significantly increased in both taurine treated groups compared to CW, while heart rates were not significantly different among the four groups. Further, all groups displayed similar renal nerve firing frequencies at rest and renal nerve responses to sodium nitroprusside and phenylephrine infusion. However, compared to CW group, CG significantly increased the power density of renin release-related frequency component, decreased that of sodium excretion-related frequency component, and decreased that of renal blood flow-related frequency component. Taurine supplementation completely abolished the effect of high sugar intake on renal sympathetic activity patterns. These data indicate that in adult male rats, high sugar intake alters the pattern but not firing frequency of sympathetic nerve activity to control renal function, and this effect can be improved by taurine supplementation.