Antenatal steroid exposure and heart rate variability in adolescents born with very low birth weight

BACKGROUND

Reduced heart rate variability (HRV) suggests autonomic imbalance in the control of heart rate and is associated with unfavorable cardiometabolic outcomes. We examined whether antenatal corticosteroid (ANCS) exposure had long-term programming effects on HRV in adolescents born with very low birth weight (VLBW).

METHODS

Follow-up study of a cohort of VLBW 14-y olds born between 1992 and 1996 with 50% exposed to ANCS. HRV in both the time and frequency domains using Nevrokard Software was determined from a 5-min electrocardiogram tracing.

RESULTS

HRV data from 89 (35 male, 53 non-black) exposed (ANCS+) and 77 (28 male, 29 non-black) unexposed (ANCS-) adolescents were analyzed. HRV did not differ between ANCS+ and ANCS- black participants. However, in non-black participants, a significant interaction between ANCS and sex was observed, with ANCS- females having significantly greater HRV than ANCS+ females and males, and ANCS- males for both time and frequency domain variables.

CONCLUSION

Among non-black adolescents born with VLBW, ANCS exposure is associated with reduced HRV with apparent sex-specificity. Reduced HRV has been associated with development of adverse cardiometabolic outcomes, thus supporting the need to monitor these outcomes in VLBW adolescents as they mature.

A Preliminary Study of the Effectiveness of an Allostatic, Closed-Loop, Acoustic Stimulation Neurotechnology in the Treatment of Athletes with Persisting Post-concussion Symptoms

BACKGROUND

Effective interventions are needed for individuals with persisting post-concussion symptoms. High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM®) is an allostatic, closed-loop, acoustic stimulation neurotechnology, designed to facilitate relaxation and self-optimization of neural oscillations.

METHODS

Fifteen athletes (seven females, mean age 18.1 years, SD 2.6) with persisting post-concussion symptoms received 18.7 (SD 6.0) HIRREM sessions over a mean of 29.6 (SD 23.2) days, including 11.3 (SD 4.6) in office days. Pre- and post-HIRREM measures included the Rivermead Post-Concussion Symptoms Questionnaire (RPQ, n = 12), the Insomnia Severity Index (ISI, n = 15), the Center for Epidemiologic Studies Depression Scale (CES-D, n = 10), short-term blood pressure and heart rate recordings for measures of autonomic cardiovascular regulation (n = 15), and reaction time by the drop-stick method (n = 7). All participants were asked about their physical activity level and sports participation status at their post-HIRREM data collection visit and 1 to 3 months afterward.

RESULTS

At the post-HIRREM visit, subjects reported improvements in all three inventories (RPQ mean change 19.7, SD 11.4, Wilcoxon p = 0.001; ISI mean change -4.1, SD 4.1, Wilcoxon p = 0.003; CES-D mean change -12.0, SD 10.0, Wilcoxon p = 0.004), including statistically significant reductions in 14 of the 16 individual items of the RPQ. There were also statistically significant improvements in baroreflex sensitivity, heart rate variability in the time domain (SDNN), and drop-stick reaction testing (baseline mean distance of 23.8 cm, SD 5.6, decreased to 19.8 cm, SD 4.6, Wilcoxon p = 0.016). Within 3 months of the post-HIRREM data collection, all 15 had returned to full exercise and workouts, and ten had returned to full participation in their athletic activity.

CONCLUSIONS

The use of HIRREM by a series of athletes with persisting post-concussion symptoms was associated with a range of improvements including, for the majority, return to full participation in their sport. The findings do not appear to be consistent with constituents of the placebo effect. A larger controlled trial is warranted.

Abstract P602: Reduced Symptoms And Improved Heart Rate Variability Associated With Use Of Closed-Loop Noninvasive Neurotechnology By Migraineurs

Introduction: Migraine is associated with impaired autonomic function, reduced heart rate variability (HRV), increased sympathetic activity, and symptoms of insomnia and depression. High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM) is a noninvasive, closed-loop acoustic stimulation neurotechnology that identifies dominant brain frequencies and translates them into audible tones, to support self-optimization of brain rhythms.

Objective: We have reported use of HIRREM is associated with improved autonomic balance in a diverse cohort. We explored for effects of HIRREM in a cohort with self-reported migraine enrolled in an IRB-approved open label feasibility study of HIRREM for diverse neuropsychological disorders.

Methods: Fifty-two subjects (42 female), mean (SD) age 38.0 (18.6), received 15.9 (3.9) HIRREM sessions (90-120 minutes each) over 9.0 (2.7) days of in-office intervention. Outcomes collected before (V1), and 13.6 (14.4) days after HIRREM completion (V2) included measures of autonomic regulation (baroreflex sensitivity, BRS, and HRV), inventories for insomnia (ISI), depression (CES-D), traumatic stress (PCL-C), and headache (MIDAS). Paired t-tests were performed. Measures of BRS and HRV (n=52) improved from V1 to V2, including HF Alpha (+8.0 ms/mmHg (SE 2.2), p<0.0012), SDNN (+6.1 ms (1.9), p=0.002), and rMSSD ms (+7.6 (2.5), p=0.004). Sympathetic tone to blood vessels and mean arterial pressure were significantly reduced. There were improvements in symptoms at V2, including ISI (n=52): -6.2 (5.7), p<0.0001; CES-D (n=38): -8.0 (9.8), p<0.0001; PCL-C (n=30): -8.2 (11.3); p<0.001; and MIDAS (n=33): -14.9 (41.7), p<0.01). No serious adverse events were reported.

Conclusions: This exploratory study shows improved measures of autonomic balance, reduced sympathetic tone, improved sleep and mood. Data suggest that HIRREM is a promising intervention that merits further investigation to mitigate the myriad effects of migraine

Abstract 136: Influence of Race and Obesity on the Renin-Angiotensin-Aldosterone System in Adolescents Born Preterm

Background: While neonatal morbidity and mortality in preterm infants have improved dramatically, the long-term cardiovascular and renal consequences of prematurity are incompletely understood. Prematurity may induce programmed changes in the renin-angiotensin (Ang)-aldosterone system (RAAS), a key regulator of cardiovascular and renal function. Race and obesity influence the RAAS and may modify the effects of prematurity on the RAAS. We hypothesized that the RAAS differs by race and obesity in adolescents born prematurely with very low birth weight (VLBW).

Methods: A cohort of 173 adolescents with VLBW was evaluated at age 14. We measured renin, aldosterone, Ang II, and Ang-(1-7) in the plasma; Ang II, Ang-(1-7), and creatinine in the urine; and we calculated the aldosterone/renin ratio and the Ang II/Ang-(1-7) ratios. We used general linear regression models to estimate the difference in the RAAS according to overweight/obesity (body mass index ≥85% for age and sex) and race, adjusting for confounding variables.

Results: On unadjusted analyses as well as analyses adjusted for sex, antenatal corticosteroid exposure, and maternal hypertension, black race was associated with decreased urinary Ang-(1-7)/creatinine (adjusted estimate -0.18, 95% CI -0.36 to -0.01, p = 0.04) and decreased renin (-0.36, -0.68 to -0.05, p = 0.03). In analyses stratified by sex, black males, but not black females, had decreased renin (-0.63, -1.1 to -0.16, p = 0.01) and aldosterone (-0.61, -1.19 to -0.04, p = 0.04). Obesity was associated with increased urinary Ang II/(1-7) (0.29, 0.04 to 0.53, p = 0.02), decreased plasma Ang-(1-7) (-0.4, -0.8 to -0.002, p = 0.05), increased plasma Ang II (0.21, 0.03 to 0.39, p = 0.02), and increased plasma Ang II/(1-7) (0.61, 0.2 to 1.01, p = 0.004).

Conclusions: In adolescents born with VLBW, there is racial variation in the RAAS. Black adolescents, especially males, have an altered renal RAAS and lower renin and aldosterone. Obesity is associated with a potentially deleterious alteration in the RAAS, with a shift in the renal and systemic RAAS towards Ang II and away from Ang-(1-7). These shifts in the RAAS associated with race and obesity may increase the risk of renal and cardiovascular disease in adolescents born with VLBW.

Abstract P627: Improved Autonomic Cardiovascular Regulation and Reduced Symptoms Associated with Use of Closed-loop Noninvasive Neurotechnology by Healthcare Workers

Introduction: Chronic stress in healthcare workers is associated with insomnia and risk for adverse health outcomes. High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM) is a noninvasive, closed-loop acoustic stimulation neurotechnology that identifies dominant brain frequencies and translates them into audible tones, to support auto-calibration and self-optimization of brain rhythms.

Objective: We explore use of HIRREM in a cohort of healthcare workers enrolled in an IRB-approved open label feasibility study of HIRREM for diverse neuropsychological disorders.

Methods: Twenty five employees (16 female), mean (SD) age 45.8 (13.9), received 14.8 (4.7) HIRREM sessions (90-120 minutes each) over 9.0 (3.6) days of in-office intervention. Data was collected before (V1), and 15.4 (11.7) days after completion (V2). Outcomes included BP and HR recordings for autonomic cardiovascular regulation (baroreflex sensitivity, BRS, and heart rate variability, HRV), with inventories for insomnia (ISI), depression (CES-D), traumatic stress (PCL-C), quality of life (EQ-5D global rating), and drop stick reaction testing (RXT). Paired t-tests were performed.

Results: BRS and HRV (n=17) improved from V1 to V2, including Sequence ALL (+2.4 ms/mmHg (SE 2.8), p=0.15), SDNN (+8.9 ms (4.1), p=0.04), and rMSSD ms (+9.2 (4.9), p=0.07). There were significant improvements in symptoms and function at V2; ISI (n=25): -8 (5.3), p<0.0001; CES-D (n=20): -7.3 (13.4), p=0.02; PCL-C (n=19): -12.1 (12.4); p<0.001; EQ-5D (n=16): +10.8 (12.5), p<0.01; RXT (n=18): -4.6 cm (5.5), p<0.01. There were no serious adverse events.

Conclusions: This exploratory study shows improved measures of cardiovascular regulation, and reduced insomnia, depression, and stress associated with use of HIRREM in a cohort of employees at an academic medical center. Data suggest that HIRREM is a promising intervention that merits further investigation to mitigate effects of chronic stress and improve wellness.

Abstract P625: Improvement of Autonomic Function and C-Reactive Protein in Military Personnel with Traumatic Stress After Use Of a Closed Loop Neurotechnology

Objective: Evaluate changes in autonomic cardiovascular control and inflammatory markers associated with use of High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM) in subjects enrolled in a pilot study for symptoms of military-related traumatic stress (MTS).

Introduction: Symptoms associated with MTS include insomnia, depression, anxiety, activated inflammatory response and impaired autonomic control. HIRREM is a noninvasive, closed-loop acoustic stimulation technology that identifies dominant brain frequencies and translates them in real time into audible tones of variable pitch and timing, to support self-updating and self-optimization of brain activity.

Methods: Eighteen service members or Veterans (1 female), mean (SD) age 40.9 (7.0), with MTS symptoms for 6 years (3.4), received 19.5 (1.1) HIRREM sessions over 12 days. Continuous recordings of blood pressure and heart rate, for analysis of baroreflex sensitivity (BRS) and heart rate variability (HRV), were done before and immediately after completion of the HIRREM intervention. Blood samples were also collected (n = 14) for measurement of catecholamines, cytokines, C-reactive protein and the renin angiotensin system (RAS) components. Paired t-tests were performed. After HIRREM, there was improved BRS measured as HF alpha (9.6 ms/mmHg, SE 3.1, p = 0.005), Sequence Down (7.6 ms/mmHg, 2.4, p = 0.005), Sequence Up (8.4 ms/mmHg, 3.0, p = 0.01), and Sequence All (7.6 ms/mmHg, 2.2, p = 0.002), as well as HRV; SDNN (12.0 ms, 3.5, p = 0.02), rMSSD (13.2 ms, 3.0, p < 0.001), LF power (1023.0 ms 2 , 346, p = 0.007), HF power (398.0 ms 2 , 142.0, p = 0.01), and total power (1420.8 ms 2 , 450.8, p = 0.005). C-reactive protein (36%, p = 0.057) was also reduced. There were no significant changes in the catecholamine, cytokines or RAS. There were no adverse events or dropouts.

Conclusions: These interim results suggest improved autonomic cardiovascular regulation, across multiple measures of BRS and HRV, and reduction in CRP associated with the use of HIRREM for symptoms of MTS. Confirmation of these results in a larger cohort may provide important insights regarding both the mechanisms associated with the beneficial effects of HIRREM, and the functional disturbances underlying MTS.

Abstract P121: Antenatal Corticosteroids and Alterations in Renal Function in Adolescents Born Preterm

Background: Treatment with antenatal corticosteroids (ANCS) hastens fetal lung development and improves survival of infants born preterm, but the long-term effects of ANCS are not well described. Animal models suggest ANCS causes programmed alterations in renal maturation, including a decreased number of functional nephrons. Data in humans suggests that prematurity is associated with subsequent development of glomerular hyperfiltration and albuminuria as precursors of chronic kidney disease. We hypothesized that ANCS exposure alters renal function in adolescents born preterm.

Methods: A cohort of 169 adolescents born prematurely, 91 of whom were exposed to ANCS, was evaluated at age 14. We measured plasma and urine creatinine (Cr) and urine albumin and calculated the estimated glomerular filtration rate (eGFR) and urine albumin-to-Cr ratio (ACR). The outcomes were albuminuria (urine ACR >30 mg/g Cr) and hyperfiltration (eGFR ≥147.5 mL/min/1.73 m 2 , the upper quintile of the cohort’s eGFR). We used multivariable logistic regression models to evaluate the association of ANCS exposure with renal outcomes, adjusting for confounding variables.

Results: In unadjusted analyses and after adjustment for race, sex, and maternal hypertension, ANCS exposure was associated with a decreased likelihood of albuminuria (adjusted OR 0.33, 95% CI 0.12 to 0.91, p = 0.03). In unadjusted analysis ANCS was associated with an increased likelihood of hyperfiltration (unadjusted OR 3.17, 1.1 to 9.15, p = 0.03), and this relationship was only slightly attenuated after adjustment for confounding variables ( p = 0.12).

Conclusions: Adolescents born prematurely who were exposed to ANCS were less likely to exhibit albuminuria, but were more likely to have hyperfiltration. ANCS could affect renal function among adolescents born prematurely.

Medullary Endocannabinoids Contribute to the Differential Resting Baroreflex Sensitivity in Rats with Altered Brain Renin-Angiotensin System Expression

CB₁ cannabinoid receptors are expressed on vagal afferent fibers and neurons within the solitary tract nucleus (NTS), providing anatomical evidence for their role in arterial baroreflex modulation. To better understand the relationship between the brain renin-angiotensin system (RAS) and endocannabinoid expression within the NTS, we measured dorsal medullary endocannabinoid tissue content and the effects of CB₁ receptor blockade at this brain site on cardiac baroreflex sensitivity (BRS) in ASrAOGEN rats with low glial angiotensinogen, normal Sprague-Dawley rats and (mRen2)27 rats with upregulated brain RAS expression. Mass spectrometry revealed higher levels of the endocannabinoid 2-arachidonoylglycerol in (mRen2)27 compared to ASrAOGEN rats (2.70 ± 0.28 vs. 1.17 ± 0.09 ng/mg tissue; P < 0.01), while Sprague-Dawley rats had intermediate content (1.85 ± 0.27 ng/mg tissue). Microinjection of the CB₁receptor antagonist SR141716A (36 pmol) into the NTS did not change cardiac BRS in anesthetized Sprague-Dawley rats (1.04 ± 0.05 ms/mmHg baseline vs. 1.17 ± 0.11 ms/mmHg after 10 min). However, SR141716A in (mRen2)27 rats dose-dependently improved BRS in this strain: 0.36 pmol of SR141716A increased BRS from 0.43 ± 0.03 to 0.71 ± 0.04 ms/mmHg (P < 0.001), and 36 pmol of SR141716A increased BRS from 0.47 ± 0.02 to 0.94 ± 0.10 ms/mmHg (P < 0.01). In contrast, 0.36 pmol (1.50 ± 0.12 vs. 0.86 ± 0.08 ms/mmHg; P < 0.05) and 36 pmol (1.38 ± 0.16 vs. 0.46 ± 0.003 ms/mmHg; P < 0.01) of SR141716A significantly reduced BRS in ASrAOGEN rats. These observations reveal differential dose-related effects of the brain endocannabinoid system that influence cardiovagal BRS in animals with genetic alterations in the brain RAS.

Effects of Resistance Training With and Without Caloric Restriction on Arterial Stiffness in Overweight and Obese Older Adults

BACKGROUND

Arterial stiffness is an important marker of vascular aging that is increased in sedentary, obese older adults. Weight loss induced by caloric restriction (CR) can improve arterial stiffness in this population; however, the effects of resistance training (RT) are not clear. This pilot study determined the effects of RT with and without CR on arterial stiffness in overweight and obese older adults.

METHODS

Participants (mean age = 68±3 years, mean body mass index = 31.1±2.7 kg/m(2), 56% female, 13% Black) were randomly assigned to 3 days/week of supervised moderate-intensity RT (n = 16) or RT+CR (n = 16) for 5 months. Three indices of arterial stiffness were measured: brachial-ankle pulse wave velocity, large artery elasticity, and small artery elasticity.

RESULTS

Body mass was significantly reduced in the RT+CR group compared to the RT group (-6.2±4.8 vs. 0.2±1.2 kg, P = 0.0006). Within-group analyses showed that none of the arterial stiffness measures changed with RT or RT+CR. There were also no significant between-group differences, though median changes in large artery elasticity were slightly greater with RT+CR: 0.7 (-2.5, 5.1) vs. 0.3 (-2.6, 0.9) ml/mm Hg × 10, P = 0.07. Changes in large artery elasticity were negatively correlated with changes in waist circumference (r = -0.36, P < 0.05), systolic blood pressure (r = -0.38, P = 0.03), and diastolic blood pressure (r = -0.41, P = 0.02).

CONCLUSIONS

The combination of RT and CR, leading to a modest amount of weight loss (7%), tended to increase large artery elasticity more than RT alone. Our data suggest that reductions in waist circumference and blood pressure may promote improvements in elasticity.

CLINICAL TRIALS REGISTRATION

Trial Number NCT01049698.

Distinct neurohumoral biomarker profiles in children with hemodynamically defined orthostatic intolerance may predict treatment options

Studies of adults with orthostatic intolerance (OI) have revealed altered neurohumoral responses to orthostasis, which provide mechanistic insights into the dysregulation of blood pressure control. Similar studies in children with OI providing a thorough neurohumoral profile are lacking. The objective of the present study was to determine the cardiovascular and neurohumoral profile in adolescent subjects presenting with OI. Subjects at 10-18 yr of age were prospectively recruited if they exhibited two or more traditional OI symptoms and were referred for head-up tilt (HUT) testing. Circulating catecholamines, vasopressin, aldosterone, renin, and angiotensins were measured in the supine position and after 15 min of 70° tilt. Heart rate and blood pressure were continuously measured. Of the 48 patients, 30 patients had an abnormal tilt. Subjects with an abnormal tilt had lower systolic, diastolic, and mean arterial blood pressures during tilt, significantly higher levels of vasopressin during HUT, and relatively higher catecholamines and ANG II during HUT than subjects with a normal tilt. Distinct neurohumoral profiles were observed when OI subjects were placed into the following groups defined by the hemodynamic response: postural orthostatic tachycardia syndrome (POTS), orthostatic hypotension (OH), syncope, and POTS/syncope. Key characteristics included higher HUT-induced norepinephrine in POTS subjects, higher vasopressin in OH and syncope subjects, and higher supine and HUT aldosterone in OH subjects. In conclusion, children with OI and an abnormal response to tilt exhibit distinct neurohumoral profiles associated with the type of the hemodynamic response during orthostatic challenge. Elevated arginine vasopressin levels in syncope and OH groups are likely an exaggerated response to decreased blood flow not compensated by higher norepinephrine levels, as observed in POTS subjects. These different compensatory mechanisms support the role of measuring neurohumoral profiles toward the goal of selecting more focused and mechanistic-based treatment options for pediatric patients with OI.

Use of an allostatic neurotechnology by adolescents with postural orthostatic tachycardia syndrome (POTS) is associated with improvements in heart rate variability and changes in temporal lobe electrical activity

Autonomic dysregulation and heterogeneous symptoms characterize postural orthostatic tachycardia syndrome (POTS). This study evaluated the effect of high-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM^®), a noninvasive, allostatic neurotechnology for relaxation and auto-calibration of neural oscillations, on heart rate variability, brain asymmetry, and autonomic symptoms, in adolescents with POTS. Seven subjects with POTS (three males, ages 15–18) underwent a median of 14 (10–16) HIRREM sessions over 13 (8–17) days. Autonomic function was assessed from 10-min continuous heart rate and blood pressure recordings, pre- and post-HIRREM. One-minute epochs of temporal high-frequency (23–36 Hz) brain electrical activity data (T3 and T4, eyes closed) were analyzed from baseline HIRREM assessment and subsequent sessions. Subjects rated autonomic symptoms before and after HIRREM. Four of seven were on fludrocortisone, which was stopped before or during their sessions. Heart rate variability in the time domain (standard deviation of the beat-to-beat interval) increased post-HIRREM (mean increase 51 %, range 10–143, p = 0.03), as did baroreflex sensitivity (mean increase in high-frequency alpha 65 %, range −6 to 180, p = 0.05). Baseline temporal electrical asymmetry negatively correlated with change in asymmetry from assessment to the final HIRREM session (p = 0.01). Summed high-frequency amplitudes at left and right temporal lobes decreased a median of 3.8 μV (p = 0.02). There was a trend for improvements in self-reported symptoms related to the autonomic nervous system. Use of HIRREM was associated with reduced sympathetic bias in autonomic cardiovascular regulation, greater symmetry and reduced amplitudes in temporal lobe high-frequency electrical activity, and a trend for reduced autonomic symptoms. Data suggest the potential for allostatic neurotechnology to facilitate increased flexibility in autonomic cardiovascular regulation, possibly through more balanced activity at regions of the neocortex responsible for autonomic management.

Clinical trial registry “Tilt Table with Suspected postural orthostatic tachycardia syndrome (POTS) Subjects,” Protocol Record: WFUBAHA01.

Abstract P633: Low Serum Vitamin D is Associated with Greater Impairment in Autonomic Function upon Head Up Tilt in Children with Orthostatic Intolerance

In previous work we identified a group of children (n = 48) between the ages of 10-18 years whose diagnostic workup for chronic nausea unexplained by conventional diagnostic tests revealed that 60% had underlying cardiovascular instability (n = 30) presenting as orthostatic intolerance (OI). The OI could be sub-classified based on head up tilt (HUT) testing into three groups: Postural Orthostatic Tachycardia Syndrome (POTS), orthostatic hypotension (OH) and syncope. Children with OI in all three groups had a greater reduction in autonomic control upon HUT manifested as greater loss of baroreflex sensitivity (BRS) and heart rate variability (HRV) and higher norepinephrine levels compared to those in the non OI group. Vitamin D deficiency is associated with impaired vascular responses to vasoconstrictors and alterations in autonomic control mechanisms in adults. In this study we sought to determine if vitamin D level is lower in these pediatric OI subjects and if it correlates with the hemodynamic responses to tilt. Serum 25(OH)D tended to be lower in OI vs non OI (18.6 ± 0.7 ng/ml, n = 25, vs 22.2 ± 2.4 ng/ml, n = 15; p = 0.16). Most importantly 25(OH)D showed a high positive correlation with supine measures of BRS (seq ALL, R = 0.51, p = 0.05), HRV (rMSSD, R = 0.44, p = 0.02) only in the OI group and there was a trend for a negative correlation with sympathovagal balance ( LF/HF ratio: R =-0.35, p = 0.08). Low 25(OH)D correlated with greater loss of both BRS (R = 0.51, p = 0.01) and HRV (R = 0.44, p = 0.05) upon HUT. These findings support the concept that low vitamin D may contribute to impaired responses to tilt in OI subjects. Further work is needed to evaluate if vitamin D supplementation will improve the vascular and hemodynamic responses to tilt and help improve the OI symptoms. Our goal is to provide a safer therapeutic alternative for the treatment of OI in children.

Abstract P149: Distinct Profiles of Brain Medullary Metabolites Detected by 1 H-Magnetic Resonance Spectroscopy Correlate with Indices of Autonomic Function and Visceral Fat in Healthy Adults

Higher forebrain myoinositol (mIns), a marker of glial inflammation/proliferation as detected by proton magnetic resonance spectroscopy (MRS), correlates with systemic inflammation. Elevated circulating markers of inflammation are associated with lower baroreceptor reflex sensitivity (BRS) and heart rate variability (HRV) as well as visceral fat or central obesity. To determine whether transmitters/metabolites in a cardiovascularly (CV) relevant brain region correlate with age-related declines in BRS and HRV and markers of abdominal fat, autonomic profiles were determined by spectral and sequence analysis from continuous blood pressure and HR values in the supine position of healthy subjects 22 - 76 yrs old (12F, 4M); subjects later underwent a single voxel (10 x 7 x 20mm) proton MRS scan of dorsal medulla on a 3T magnet (n = 11; 9F, 2M) and measures of abdominal fat by computerized tomography (CT) (n = 9; 7F,2M). The mean arterial pressure was 88 ± 3 mm Hg, HR 64 ± 3 beats/min and BMI 27 ± 1 kg/m 2 . Glutamate (Glu) correlated directly with vagal (HF RRI r = 0.72, p < 0.02) and inversely with sympathetic (LF RRI r = -0.72, p < 0.02) control of HR. Markers of Glu metabolism and neuronal integrity/activity, N-acetyl-aspartate acid (NAA) + N-acetyl aspartyl glutamate (NAAG), did not correlate with age, but did correlate inversely with BRS (Seq ALL: r = -0.69, P < 0.02), HRV (rMSSD: r = -0.76, p < 0.008) and directly with HR (r = 0.68, p < 0.03). Total visceral fat had a negative correlation with BRS (Seq Up: r = -0.70, p < 0.02). mIns and markers of demyelination and reduced axonal integrity such as Glycerophosphocholine (GPC) and total choline containing compounds (GPC+PCh) exhibited striking positive correlations with percent visceral fat (r = 0.97, 0.81 and 0.82, P < 0.02). BMI and GPC correlated with HR (r = 0.55, 0.72, p < 0.04), but neither these nor mIns or choline compounds correlated with autonomic function. Thus, in healthy adults, Glu concentration in dorsal medulla directly correlates with cardiac vagal function, whereas markers of Glu metabolism inversely correlate with BRS and HRV. In contrast, markers of glial inflammation directly associate with increases in visceral adiposity, but not autonomic dysfunction. P30-AG21332, Farley Hudson, Hypertension & Vasc Res Ctr

Abstract P069: 1H-Magnetic Resonance Spectroscopy Reveals Elevation of MyoInositol and Other Markers of Inflammation in the Dorsal Medulla of Children with Orthostatic Intolerance

Children with orthostatic intolerance (OI) have exaggerated decreases in heart rate variability (HRV) and suppression of baroreflex sensitivity (BRS) with standing. Inflammation is proposed as a possible factor contributing to impaired HRV in cardiometabolic disorders; whether systemic or brain inflammation better predicts impaired HRV is arguable. We used 1H magnetic resonance spectroscopy (MRS) to quantify markers of neuronal and glial integrity in children with OI compared with asymptomatic controls. Fifteen subjects ages 10-18 years were evaluated for blood pressure, HR, and autonomic function in supine and upright positions and 7 tested positive for OI. An average of 2 weeks following OI testing all subjects underwent 1H-MRS scans of dorsal medulla on a clinical 3T magnet while supine. OI subjects had higher myoinositol (mIns) as a marker of glial inflammation than asymptomatic controls (7.8 ± 0.4 vs 5.6 ± 0.9 mmol/L, p = 0.03). Trends were observed for higher glycerophosphocholine (higher GPC, reduced myelination and axonal integrity) (2.3 ± 0.2 vs 1.8 ± 0.2 mmol/L, p = 0.08) and lower N-acetyl aspartate (lower NAA, reduced neuronal integrity) (2.8 ± 0.3 vs. 3.7 ± 0.4 mmol/L, p = 0.1) in OI subjects vs controls (mean ± SEM). mIns concentrations did not correlate with indices of autonomic function measured in the supine position. However, supine measures of mIns correlated with autonomic measures taken in the upright position: negatively correlated with spontaneous BRS (R = -0.64, p = 0.01), parasympathetic tone measured by high frequency alpha index (HFα, R= -0.547, p=0.04) and HRV measured by root of mean square of successive differences (rMSSD, R = -0.45, p = 0.09); there was a positive correlation with HR (R = 0.53, p < 0.05). In summary, children with OI have higher mIns in dorsal medulla while supine that is predictive of impairment in BRS, HRV and parasympathetic tone upon upright posture. This first report that OI in children is associated with elevated mIns, a marker of glial inflammation in a variety of neuropathies, raises the intriguing possibility that brain inflammation plays a role in the autonomic dysfunction observed while standing in these subjects. Support: Centers for Integrative Medicine and Hypertension & Vascular Research; AHA12CRP9420029

Abstract 126: Systemic Administration of (Pyr1)-Apelin-13 at Late Pregnancy Reduces Blood Pressure, Proteinuria, and Improves Autonomic Function in Preeclamptic Rats

Preeclampsia is associated with maternal perinatal morbidity and mortality and a high risk of premature birth and intrauterine growth restriction. The apelin system is a novel pleiotropic pathway with a potential for therapeutic targeting in preeclampsia. We have previously reported that total apelin content is lower in human preeclamptic chorionic villi. In this study, we determined whether (Pyr1)-apelin-13 improves hypertension, proteinuria, fetal characteristics, uteroplacental hemodynamics, and the autonomic function in preeclamptic rats (TgA, female transgenic for human angiotensinogen mated to male transgenic for human renin). (Pyr1)-apelin-13 (2 mg/kg/day) (n=7) or saline (n=5) was infused in TgA via osmotic minipumps starting at day 13 of gestation, when blood pressure begins to increase in these animals. Pregnant SD (n=6) rats were used as controls. At the 20th day of pregnancy, TgA rats had higher MAP (138±6 vs. 79±3 mmHg in SD, p<0.001) which was reduced by (Pyr1)-apelin treatment to 119±2 mmHg vs. TgA, p<0.006. TgA rats also had impaired heart rate variability measured as root of mean successive differences (rMSSD) compared with SD (2.7±0.4 vs. 3.8±0.3 ms in SD, p<0.05). Apelin treatment normalized rMSSD to 3.6±0.3, p<0.05. Similarly, baroreflex sensitivity measured in the sequence domain was lower in TgA (0.7±0.1 vs. 2.6±0.5 ms/mmHg in SD, p<0.01) and normalized with (Pyr1)-apelin-13 to 2.0 ± 0.4 ms/mmHg, p<0.05. Proteinuria was greater in TgA (53±9 vs. 10±2 mg/kg/day, p<0.001), and normalized by (Pyr1)-apelin-13 (18±6, p<0.05). Pup (3.0±0.1 vs. 3.7±0.1 g, p<0.01) and placental weight (0.41±0.01 vs. 0.45±0.01 g, p<0.01), and pup number (10.7±1.1 vs. 14.0±0.8, p<0.01) were lower in TgA vs. SD; however they were not changed by (Pyr1)-apelin-13. Uterine artery peak systolic velocity was not different between SD and TgA, but increased with (Pyr1)-apelin-13 treatment (179.5±16.7 vs. 122.6±16.7 ml/min, p<0.05) with no change in resistance index. In conclusion, our findings suggest that (Pyr1)-apelin-13 may be beneficial for the treatment of preeclampsia due to its hemodynamic and renoprotective effects. We also report for the first time that these changes may involve central control of the cardiovascular system.

Abstract 081: Intracerebroventricular (ICV) Infusion of Angiotensin-(1-7) Lowers Blood Pressure and Improves Autonomic Function in Antenatal Betamethasone Exposed Sheep

We have previously shown that antenatal betamethasone exposure in sheep is associated with a deficiency in angiotensin (Ang)-(1-7) levels in the cerebrospinal fluid of these betamethasone exposed (BMX) sheep and impaired baroreflex sensitivity for control of heart rate (BRS) by 6 weeks of age followed by persistent suppression of the reflex and elevation in mean blood pressure (MAP) by 6 months of age. In this study we sought to determine if supplementation of Ang-(1-7) administered via continuous infusion into the lateral ventricle of 4 month old BMX lambs (1-7, n=4) at a dose of 1.25ug/kg/hr for 1 week would improve the BRS, heart rate variability (HRV) and lower MAP and blood pressure variability (BPV). The control group received ICV artificial cerebrospinal fluid (aCSF, n=4). MAP and heart rate were recorded continuously via femoral arterial catheters and digitized before and one week after the ICV infusion. Both blood pressure and heart rate were analyzed to obtain measures of spontaneous BRS, HRV and BPV in the frequency and time domain. There were no differences in any of the measures between the two groups at baseline and no changes in the aCSF group after 1 week of ICV aCSF administration. Meanwhile, Ang-(1-7) ICV treatment significantly improved all measures of BRS compared to baseline, (HFa, 5.3±0.9 vs. 2.4±0.5 ms/mm Hg, p=0.03) and sequence ALL (6.5±1.6 vs. 1.9±0.9 ms/mm Hg, p=0.01). Ang-(1-7) also improved HRV measured as rMSSD (11.6±1.6 vs. 7±1.2 ms at baseline, p=0.04). Ang-(1-7) administration lowered MAP by 11.5 mm Hg (p < 0.05) compared to a rise of 2.0 mm Hg in the control group with no significant changes in heart rate or BPV in either group. These data support the hypothesis that Ang-(1-7) deficiency in the CSF contributes to the impaired autonomic function and reduced parasympathetic tone in betamethasone exposed sheep and replacement of the peptide in the brain will help restore these measures to normal levels. Elevating Ang-(1-7) levels in humans exposed antenatally to betamethasone may have beneficial cardiovascular effects.

Abstract P189: Angiotensin II - Endocannabinoid Interactions in the Nucleus of the Solitary Tract are Important for Regulation of Baroreflex Control of Heart Rate

Hypertension resulting from elevated brain angiotensin (Ang) II is associated with impaired functioning of neural reflexes regulating sympathetic and parasympathetic outflow. Restoration of normal baroreflex sensitivity (BRS) for control of heart rate (HR) is achieved in a rat model of Ang II - dependent hypertension [ (mRen2)27 transgenic rats ] by local injection of the cannabinoid CB 1 receptor antagonist rimonabant (SR141716A), a CB 1 receptor antagonist, into the solitary tract nucleus (NTS) of anesthetized rats or by chronic oral rimonabant treatment, which has central and peripheral sites of action. Together with elevated brain dorsal medullary tissue concentrations of 2-arachidonylglycerol present in the (mRen2)27 rats, these findings are consistent with an activated endocannabinoid system contributing to the impaired BRS in these animals. To further explore acute interactions between Ang II - mediated suppression of BRS and the endocannabinoids, Ang II was injected into NTS of anesthetized Sprague-Dawley rats 10 minutes following NTS injection of rimonabant or aCSF (120 nL, bilaterally). In the presence of aCSF, Ang II reduced BRS by ~50% (In msec/mm Hg: 1.14 ± 0.14 before versus 0.53 ± 0.16; n = 7, p < 0.008); this effect was abolished in the presence of rimonabant (In msec/mm Hg: 0.92 ± 0.16 before versus 0.86 ± 0.21; n = 4, p = 0.8). There was no difference in mean arterial pressure or heart rate before or after Ang II treatment in either aCSF or rimonabant groups. Thus, the data support the interpretation that Ang II - mediated attenuation of BRS for control of HR involves release of endocannabinoids. Others report that the pressor actions following acute local injections of Ang II into the hypothalamic paraventricular nucleus are prevented by blockade of CB 1 receptors. We conclude that functional interactions between these two systems occur at multiple brain sites relevant to blood pressure control mechanisms and together the findings support a role for elevated brain endocannabinoids as contributors to the altered reflexes characteristic of Ang II - dependent hypertension. Support: HL-51952, DA-024863 and DA-03690, the Hypertension & Vascular Research Center, Farley[[Unable to Display Character: &#8208;]]Hudson Foundation

Abstract P175: Impairment of Autonomic Function Precedes Blood Pressure Elevation in Rat Model of Pre-eclampsia

Hypertensive disorders of pregnancy including pre-eclampsia affect about 5-7% of all pregnant women and can cause severe acute morbidity, long-term disability and death among mothers and babies. Impairment of heart rate variability predicts risk of cardiovascular disease and all cause mortality. In this study we investigated the hypothesis that impairment of the autonomic function at early time point during pregnancy precedes and may lead to the elevation of blood pressure.

To test this hypothesis, blood pressure and heart rate were recorded under 2% isoflurane in 7 day pregnant rats generated via mating of the transgenic female rat containing the human angiotensinogen gene with the male transgenic containing human renin (hREN), the hAGTхhREN rat (TgA, n=8) which develop increased blood pressure, proteinuria and increased sensitivity to angiotensin II in the last half of gestation. The reverse mating of male containing the human angiotensinogen gene with the female transgenic containing human renin (TgR, n=8) which do not develop preeclampsia, and pregnant SD (n=8) rats at day 7 of gestation were used as controls.

By the 7th day of pregnancy, TgA rats had significantly impaired heart rate variability measured as root of mean successive differences (rMSSD) compared to SD and TgR (2.39 ±0.3 ms vs. 3.4 ± 0.2 in SD or 3.4 ±0.1 in TgR) and impaired baroreflex sensitivity measured as HF alpha (1.2±0.3 ms/mmHg vs. 2.5±0.4, SD or 1.7±0.26, TgR)

There was no difference in systolic arterial pressure or heart rate among the three groups at this time point but diastolic pressure was higher in TgA and TgR (91± 3.5 vs. 85±2.4 or vs. 75 ±2 mmHg in SD rats)

Although the predictive value of impaired baroreflex and heart rate variability in preeclampsia development needs further investigation, our findings suggest that these changes at early pregnancy precede and may contribute to the significant rise in pressure in the last half of gestation in this rat model of pre-eclampsia which may have significant clinical implications.

Rightward dominance in temporal high-frequency electrical asymmetry corresponds to higher resting heart rate and lower baroreflex sensitivity in a heterogeneous population

OBJECTIVE

Explore potential use of a temporal lobe electrical asymmetry score to discriminate between sympathetic and parasympathetic tendencies in autonomic cardiovascular regulation.

METHODS

131 individuals (82 women, mean age 43.1, range 13-83) with diverse clinical conditions completed inventories for depressive (CES-D or BDI-II) and insomnia-related (ISI) symptomatology, and underwent five-minute recordings of heart rate and blood pressure, allowing calculation of heart rate variability and baroreflex sensitivity (BRS), followed by one-minute, two-channel, eyes-closed scalp recordings of brain electrical activity. A temporal lobe high-frequency (23-36 Hz) electrical asymmetry score was calculated for each subject by subtracting the average amplitude in the left temporal region from amplitude in the right temporal region, and dividing by the lesser of the two.

RESULTS

Depressive and insomnia-related symptomatology exceeding clinical threshold levels were reported by 48% and 50% of subjects, respectively. Using a cutoff value of 5% or greater to define temporal high-frequency asymmetry, subjects with leftward compared to rightward asymmetry were more likely to report use of a sedative-hypnotic medication (42% vs. 22%, P = 0.02). Among subjects with asymmetry of 5% or greater to 30% or greater, those with rightward compared to leftward temporal high-frequency asymmetry had higher resting heart rate (≥5% asymmetry, 72.3 vs. 63.8, P = 0.004; ≥10%, 71.5 vs. 63.0, P = 0.01; ≥20%, 72.2 vs. 64.2, P = 0.05; ≥30%, 71.4 vs. 64.6, P = 0.05). Subjects with larger degrees of rightward compared to leftward temporal high-frequency asymmetry had lower baroreflex sensitivity (≥40% asymmetry, 10.6 vs. 16.4, P = 0.03; ≥50% asymmetry, 10.4 vs. 16.7, P = 0.05).

CONCLUSION

In a heterogeneous population, individuals with rightward compared to leftward temporal high-frequency electrical asymmetry had higher resting heart rate and lower BRS. Two-channel recording of brain electrical activity from bilateral temporal regions appears to hold promise for further investigation as a means to assess cortical activity associated with autonomic cardiovascular regulation.

Allopurinol alleviates hypertension and proteinuria in high fructose, high salt and high fat induced model of metabolic syndrome

Metabolic syndrome (MetS) is a global epidemic associated with great socioeconomic and public health impact. Prevalence of the MetS has been consistently associated with cardiorenal mortality. The objective of this study was to investigate the effect of allopurinol treatment on various components of an established MetS in rats. In a first group, MetS was induced in male Wistar rats by the addition of 10% fructose to drinking water and placing the rats on high-fat and high-salt diet for 12 weeks (M). In the second group, MetS was induced for 12 weeks plus allopurinol administration (20 mg/kg/d) orally for 4 weeks starting at week 9 (MA). The third group was control (C) group that received a normal diet. The M group had higher blood pressure (BP) (85.5 ± 3.17 vs 66.1 ± 3.3 mm Hg) and proteinuria (1.8 ± 0.3 vs 0.59 ± 0.13 g/d) compared with the C group. Allopurinol reversed the BP and proteinuria in MA rats to the control level. Allopurinol administration suppressed the low-grade inflammation associated with MetS and reversed the increases in kidney transforming growth factor beta and urine 8-isoprostane acid observed in the MA group to control levels. In addition, allopurinol reduced angiotensin II and angiotensin receptor type 1 levels in the kidney of MA rats compared with the M group. The administration of allopurinol for short term in an established MetS model reduced features of the MetS especially hypertension and proteinuria. Addition of allopurinol to the therapy of MetS may provide superior means to alleviate hypertension and proteinuria associated with MetS.

Abstract 513: Impaired Hemodynamic Response to Head up Tilt in Adolescents Presenting with Chronic Nausea and Orthostatic Intolerance

We previously reported that ~70% of adolescents presenting to a Pediatric GI clinic for chronic nausea exhibit orthostatic intolerance (OI) in response to head upright tilt testing (HUT). The objective of this study was to determine whether supine mean arterial pressure or hemodynamic responses to HUT differ in these patients. Forty-eight patients (mean age of 15 [10-18] years, 36 females) completed a 45 minutes 0 to 70° HUT. Continuous blood pressure and heart rate recordings were acquired using non-invasive finger cuff. Thirteen subjects had normal tilt (Normal) while thirty five demonstrated OI. There were no differences between the two groups in supine blood pressures (BP), baroreflex sensitivity measured by frequency method in HF range (BRS), heart rate variability (HRV) measured as the root of mean square of successive differences (rMSSD), blood pressure variability (BPV) measured as standard deviation of mean arterial pressure (SDMAP) or the sympathovagal balance measure LF RRI /HF RRI . HUT caused a greater increase in heart rate in OI group (from 71 ± 6 beats/min to 104 ± 4 in OI vs from 75 ± 3 to 95 ±3 in normal, p=0.01) which was accompanied with lesser increase in BP (mainly due to lack of increase in diastolic) in the OI group. There was a trend for greater reduction in BRS in OI subjects (from 28.5 ± 13 ms/mm Hg to 6.3 ± 0.8 in OI vs from 21.1 ± 3.6 to 12.0 ± 2.9 in normal, p=0.09). HUT impaired HRV in both groups compared to supine values but the reduction was greater in OI group (-66.7 ± 4 % vs -52.0 ±5.6 in normal, p=<0.001). SDMAP increased by HUT compared to supine but to a greater extent in OI (40.6 ± 4 % vs 13.4 ± 8 in normal, p=0.02). LF RRI /HF RRI increased to a greater magnitude in OI group with HUT (from 1.8 ± 0.8 to 6.8 ± 0.8 in OI vs from 1.14 ± 0.18 to 4.1 ±0.7 in normal, p=0.02). These data reveal that the adolescents with orthostatic intolerance have attenuated parasympathetic responses and exaggerated activation of the sympathetic system to the heart and blood vessels. Despite these responses, subjects fail to maintain BP. Similar to previous studies in other subjects with OI, the excessive tachycardia often followed by syncope in most of these adolescents may reflect a loss of vascular responses to the activation of sympathetic and neurohumoral stimuli. Support: AHA12CRP9420029

Abstract 462: Effect of Adding Beet Root Juice to Exercise on Physical Performance and Cardiovascular Measures in Old Hypertensive Subjects

Hypertension and diminished blood flow to muscles and brain are common problems for the elderly that may lead to impaired cognition and physical performance and poor cardiovascular outcomes. Exercise improves blood pressure and brain blood flow. Thus, any intervention that can improve exercise effects in hypertensive individuals may have beneficial effects. High nitrate containing beetroot juice (BRJ) has been demonstrated to increase exercise tolerance and improve blood flow to working muscles. In this study we examined the effect of adding BRJ to an exercise regimen on exercise performance and cardiovascular measures in old subjects. Participant (n=26; mean age=65 yrs, range 57-77) with controlled hypertension (on 2 or more medications) were assigned to either exercise with BRJ+nitrate (BRJ+) (n=13, 6F) or BRJ-nitrate placebo drink (Placebo) (n=13, 7F). The exercise intervention was a 6-week treadmill walking program of self-paced. Participants walked 3 times per week for a maximum of 50 minutes per session. Participants also consumed 140 ml BRJ+ nitrate or BRJ-nitrate daily for 6 weeks. There were no differences between groups in mean VO 2 max at the beginning of study (placebo = 19.4 ± 0.5 ml O 2 /kg/min; BRJ = 19.4 ± 0.5 ml O 2 /kg/min) and change VO 2 max by the end of the intervention (increase of 1.15 ml O 2 /kg/min in placebo vs 0.9 ml O 2 /kg/min in BRJ+). There were no differences between groups in 24 hour ambulatory mean arterial pressure (MAP) or heart rate at the beginning of study. Heart rate and MAP showed similar reductions in both groups (4 beats/min for heart rate and 5 mm Hg for MAP). Similarly total arterial compliance was improved in both groups (placebo from 15.1 ± 3.7 ml/mm Hg to 18.3 ± 4.8, p = 0.02; BRJ+ from 18.3 ± 5.0 to 20.5 ± 3.9 ml/mm Hg; p = 0.04). There was no additional benefit of BRJ+ in the cardiovascular measures above that seen with exercise alone.

In summary, in this cohort of controlled hypertensive elderly, addition of BRJ with nitrate to exercise has no additional benefits on physical performance or cardiovascular function. Further studies are warranted in different cohorts such as drug naïve or uncontrolled hypertensive to further characterize any possible benefits of BRJ. Support from WFU Translational Science Center

Abstract 033: Novel Neurohumoral Responses to Head Upright Tilt Testing in Children with Chronic Nausea and Orthostatic Intolerance

Children with chronic unexplained nausea have a high incidence of orthostatic intolerance (OI), with exaggerated suppression of baroreflexes upon standing. The renin-angiotensin system (RAS) is known to play a role in disorders related to OI likely as a compensatory mechanism for CV regulation. The objective of this study was to characterize the neurohumoral response to head upright tilt testing (HUT) in children with chronic nausea and OI. Forty-eight patients (mean age [range] of 15 [10-18] years)(36 females, 12 males) completed HUT. GI symptoms including nausea were reported during HUT. Subjects were maintained supine for 15 min before 45 min 70° HUT. Plasma hormones catecholamines (Cat), epinephrine (Epi), norepinephrine (NE), vasopressin (AVP), aldosterone (Aldo), renin, and angiotensins [Ang-(1-7) and AngII] were measured in blood sampled immediately before and after 15 min of upright tilt. Of the 48 HUTs, 35 subjects demonstrated OI. There were no differences in supine blood pressures (BP) or humoral measures between groups. OI subjects had lower systolic (105 ± 4 vs. 127 ± 4 mm Hg, p=0.001), diastolic (61 ± 2 vs. 77 ± 2, p<0.0001), and mean arterial (76 ± 2 vs. 93 ± 2, p=0.0002) BPs during HUT compared to normal subjects (mean ± SEM). They also had higher Cat (625 ±44 vs. 466 ± 61 pg/ml, p=0.02), AngII (48 ± 3 vs. 35 ± 4 pg/ml, p=0.04), and AVP (46 ± 12 vs. 18 ± 14 pg/ml, p=0.01) during HUT compared to non-OI subjects. There was a negative correlation between Ang-(1-7) and NE at baseline (r=-0.6, p<0.05) and HUT (r=-0.6, p=0.03) in Non-OI subjects that was not seen in OI subjects. Nausea was reproduced by HUT in 42% (20 of 48) of this cohort. Nausea subjects did not have a change in DBP (61 ± 2 vs. 61 ± 3 mm Hg) upon tilt, but had significantly higher AVP (72 ± 20 pg/ml, p=0.01) during HUT compared to subjects who did not experience nausea (15 ± 7, p=0.001). Children with chronic nausea testing positive for OI have elevated Cat, AngII, and AVP levels upon HUT. Elevated serum AVP may be a key trigger to nausea with orthostatic challenge independent of OI on HUT. In addition to this humoral response, the absence of change in DBP upon standing suggests a failure in both the sympathetic nervous system and RAS compensatory mechanisms necessary to sustain HUT in children with chronic nausea and OI.

Acute and chronic systemic CB1 cannabinoid receptor blockade improves blood pressure regulation and metabolic profile in hypertensive (mRen2)27 rats

We investigated acute and chronic effects of CB₁ cannabinoid receptor blockade in renin‐angiotensin system‐dependent hypertension using rimonabant (SR141716A), an orally active antagonist with central and peripheral actions. In transgenic (mRen2)27 rats, a model of angiotensin II‐dependent hypertension with increased body mass and insulin resistance, acute systemic blockade of CB₁ receptors significantly reduced blood pressure within 90 min but had no effect in Sprague‐Dawley rats. No changes in metabolic hormones occurred with the acute treatment. During chronic CB₁ receptor blockade, (mRen2)27 rats received daily oral administration of SR141716A (10 mg/kg/day) for 28 days. Systolic blood pressure was significantly reduced within 24 h, and at Day 21 of treatment values were 173 mmHg in vehicle versus 149 mmHg in drug‐treated rats (P < 0.01). This accompanied lower cumulative weight gain (22 vs. 42 g vehicle; P < 0.001), fat mass (2.0 vs. 2.9% of body weight; P < 0.05), and serum leptin (2.8 vs. 6.0 ng/mL; P < 0.05) and insulin (1.0 vs. 1.9 ng/mL; P < 0.01), following an initial transient decrease in food consumption. Conscious hemodynamic recordings indicate twofold increases occurred in spontaneous baroreflex sensitivity (P < 0.05) and heart rate variability (P < 0.01), measures of cardiac vagal tone. The beneficial actions of CB₁ receptor blockade in (mRen2)27 rats support the interpretation that an upregulated endocannabinoid system contributes to hypertension and impaired autonomic function in this angiotensin II‐dependent model. We conclude that systemic CB₁ receptor blockade may be an effective therapy for angiotensin II‐dependent hypertension and associated metabolic syndrome.

Acute and chronic systemic CB₁ cannabinoid receptor blockade significantly lowers blood pressure in Angiotensin II‐dependent hypertensive (mRen2)27 rats, with a concomitant positive influence over conscious autonomic blood pressure regulation and metabolic profile. Results from our study indicate novel mechanisms for maintenance of hypertension, metabolic syndrome, and impaired autonomic control of blood pressure associated with upregulation of Angiotensin II signaling.

A bihemispheric autonomic model for traumatic stress effects on health and behavior

A bihemispheric autonomic model (BHAM) may support advanced understanding of traumatic stress effects on physiology and behavior. The model builds on established data showing hemispheric lateralization in management of the autonomic nervous system, and proposes that traumatic stress can produce dominant asymmetry in activity of bilateral homologous brain regions responsible for autonomic management. Rightward and leftward dominant asymmetries are associated with sympathetic high arousal or parasympathetic freeze tendencies, respectively, and return to relative symmetry is associated with improved autonomic regulation. Autonomic auto-calibration for recovery (inverse of Jacksonian dissolution proposed by polyvagal theory) has implications for risk behaviors associated with traumatic life stress. Trauma-induced high arousal may be associated with risk for maladaptive behaviors to attenuate arousal (including abuse of alcohol or sedative-hypnotics). Trauma-induced freeze mode (including callous-unemotional trait) may be associated with low resting heart rate and risk for conduct disorders. The model may explain higher prevalence of leftward hemispheric abnormalities reported in studies of violence. Implications of the BHAM are illustrated through case examples of a military special operations officer with history of traumatic brain injury and post-traumatic stress disorder, and a university student with persisting post-concussion symptoms. Both undertook use of a noninvasive closed-loop neurotechnology - high-resolution, relational, resonance-based, electroencephalic mirroring - with ensuing decrease in hemispheric asymmetry, improvement in heart rate variability, and symptom reduction. Finally, the BHAM aligns with calls for researchers to use brain-behavioral constructs (research domain criteria or RDoC, proposed by the National Institutes of Mental Health) as building blocks for assessment and intervention in mental health science.