Alleviating Hypertension by Selectively Targeting Angiotensin Receptor-Expressing Vagal Sensory Neurons.

Cardiovascular homeostasis is maintained, in part, by neural signals arising from arterial baroreceptors that apprise the brain of blood volume and pressure. Here, we test whether neurons within the nodose ganglia that express angiotensin type-1a receptors (referred to as NGAT1aR) serve as baroreceptors that differentially influence blood pressure (BP) in male and female mice. Using Agtr1a-Cre mice and Cre-dependent AAVs to direct tdTomato to NGAT1aR, neuroanatomical studies revealed that NGAT1aR receive input from the aortic arch, project to the caudal nucleus of the solitary tract (NTS), and synthesize mechanosensitive ion channels, Piezo1/2 To evaluate the functionality of NGAT1aR, we directed the fluorescent calcium indicator (GCaMP6s) or the light-sensitive channelrhodopsin-2 (ChR2) to Agtr1a-containing neurons. Two-photon intravital imaging in Agtr1a-GCaMP6s mice revealed that NGAT1aR couple their firing to elevated BP, induced by phenylephrine (i.v.). Furthermore, optical excitation of NGAT1aR at their soma or axon terminals within the caudal NTS of Agtr1a-ChR2 mice elicited robust frequency-dependent decreases in BP and heart rate, indicating that NGAT1aR are sufficient to elicit appropriate compensatory responses to vascular mechanosensation. Optical excitation also elicited hypotensive and bradycardic responses in ChR2-expressing mice that were subjected to deoxycorticosterone acetate (DOCA)-salt hypertension; however, the duration of these effects was altered, suggestive of hypertension-induced impairment of the baroreflex. Similarly, increased GCaMP6s fluorescence observed after administration of phenylephrine was delayed in mice subjected to DOCA-salt or chronic delivery of angiotensin II. Collectively, these results reveal the structure and function of NGAT1aR and suggest that such neurons may be exploited to discern and relieve hypertension.

Evaluation of the Implementation of Multiple Enhanced Recovery After Surgery Pathways Across a Provincial Health Care System in Alberta, Canada.

Importance: Engaging multidisciplinary care teams in surgical practice is important for the improvement of surgical outcomes. Objective: To evaluate the association of multiple Enhanced Recovery After Surgery (ERAS) pathways with ERAS guideline adherence and outcomes. Design, Setting, and Participants: This quality improvement study compared a pre-ERAS cohort (2013-2017) with a post-ERAS cohort (2014-2018). All patients were from Alberta Health Services in Alberta, Canada, and had available ERAS and up to 1-year postsurgery administrative data. Data collected included age, sex, body mass index, tobacco and alcohol use, diabetes, comorbidity index, and surgical characteristics. Data analysis was performed from May 7, 2020, to February 1, 2021. Interventions: Implementation of 5 ERAS pathways (colorectal, liver, pancreas, gynecologic oncology, and radical cystectomy) across 9 sites. Main Outcomes and Measures: Adherence to ERAS guidelines was measured by the percentage of patients whose care met the common ERAS pathway care element criteria. Surgical procedures were grouped by complexity; complications were classified by severity. Outcome measures for the pre-post-ERAS cohorts included length of stay (LOS), readmission, complications, and mortality. Results: A total of 7757 patients participated in the study, including 984 in the pre-ERAS cohort (median [interquartile range] age, 62 [53-71] years; 526 [53.5%] female) and 6773 in the post-ERAS cohort (median [interquartile range] age, 62 [53-71] years; 3470 [51.2%] male). In the total cohort, care-element adherence improved from 52% to 76% (P < .001), no significant differences were found in serious complications (from 6.2% to 4.9%; P = .08) or 30-day mortality (from 0.71% to 0.93%; P = .50), 1-year mortality decreased from 7.1% to 4.6% (P < .001), mean (SD) LOS decreased from 9.4 (7.0) to 7.8 (5.0) days (P < .001), and 30-day readmission rates were unchanged (from 13.4% to 11.7%; P = .12). After adjustment for patient characteristics, the LOS mean difference decreased 0.71 days (95% CI, -1.13 to -0.29 days; P < .001), with no significant differences in adjusted 30-day readmission (-3.5%; 95% CI, -22.7% to 20.4%; P = .75), serious complications (1.3%; 95% CI, -26.2% to 39.0%; P = .94), or mortality (30-day mortality: 42% [95% CI, -35.4% to 212.3%]; P = .38; 1-year mortality: 8% [95% CI, -20.5% to 46.8%]; P = .62). The adjusted 1-year readmission rate was -15.6% (95% CI, -27.7% to -1.5%; P = .03) in favor of ERAS, and readmission LOS was shorter by 1.7 days (95% CI, -3.3 to -0.1 days; P = .04). Conclusions and Relevance: The results of this quality improvement study suggest that implementation of ERAS across multiple pathways may improve health care practitioner adherence to ERAS guidelines, LOS, and readmission rates at a system level.

ACE2 activator diminazene aceturate reduces adiposity but preserves lean mass in young and old rats.

The obesity epidemic is multi-generational and is particularly debilitating in the aging population, necessitating the use of pharmaceutical interventions. Recent evidence suggests that increasing the activity of the angiotensin converting enzyme-2 [ACE2]/angiotensin-(1-7)[Ang-(1-7)]/Mas receptor (MasR) axis in obese animal models leads to significant reductions in body weight. It was hypothesized that activation of ACE2 via diminazene aceturate (DIZE) will significantly reduce body weight of rats fed a high fat diet. Young and old (4 and 23 months, respectively) male Fisher 344 × Brown Norway rats were fed 60% high fat diet for one week, and subsequently given either 15 mg/kg/day DIZE s.c. or vehicle for three weeks. DIZE treatment resulted in a significant reduction of food intake and body weight in both young and old animals. However, that decrease was so dramatic in the older animals that they all nearly stopped eating. Interestingly, the TD-NMR assessments revealed that the weight-loss was primarily a result of decreased body fat percentage, with a relative preservation of lean mass. Tissue weights confirm the significant loss of white adipose tissue (WAT), with no change in muscle weights. Gene expression and serum ACE2 activity analyses implied that increased activation of the ACE2/Ang-(1-7)/MasR axis plays a role in reducing fat mass. Collectively, our results suggest that DIZE may be a useful tool in the study of obesity; however, caution is recommended when using this compound in older animals due to severe anorectic effects, although there is a mechanism by which muscle is preserved.

Coupling corticotropin-releasing-hormone and angiotensin converting enzyme 2 dampens stress responsiveness in male mice.

This study used mice to evaluate whether coupling expression of corticotropin-releasing hormone (CRH) and angiotensin converting enzyme 2 (ACE2) creates central interactions that blunt endocrine and behavioral responses to psychogenic stress. Central administration of diminazene aceturate, an ACE2 activator, had no effect on restraint-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis; however, mice that ubiquitously overexpress ACE2 had reduced plasma corticosterone (CORT) and pituitary expression of POMC mRNA. The Cre-LoxP system was used to restrict ACE2 overexpression to CRH synthesizing cells and probe whether HPA axis suppression was the result of central ACE2 and CRH interactions. Within the paraventricular nucleus of the hypothalamus (PVN), mice with ACE2 overexpression directed to CRH had a ≈2.5 fold increase in ACE2 mRNA, which co-localized with CRH mRNA. Relative to controls, mice overexpressing ACE2 in CRH cells had a decreased CORT response to restraint as well as decreased CRH mRNA in the PVN and CEA and POMC mRNA in the pituitary. Administration of ACTH similarly increased plasma CORT, indicating that the blunted HPA axis activation that accompanies ACE2 overexpression in CRH cells is centrally mediated. Anxiety-like behavior was assessed to determine whether the decreased HPA axis activation was predictive of anxiolysis. Mice with ACE2 overexpression directed to CRH cells displayed decreased anxiety-like behavior in the elevated plus maze and open field when compared to that of controls. Collectively, these results suggest that exogenous ACE2 suppresses CRH synthesis, which alters the central processing of psychogenic stress, thereby blunting HPA axis activation and attenuating anxiety-like behavior.

The intricacies of the renin-angiotensin-system in metabolic regulation.

Over recent years, the renin-angiotensin-system (RAS), which is best-known as an endocrine system with established roles in hydromineral balance and blood pressure control, has emerged as a fundamental regulator of many additional physiological and pathophysiological processes. In this manuscript, we celebrate and honor Randall Sakai's commitment to his trainees, as well as his contribution to science. Scientifically, Randall made many notable contributions to the recognition of the RAS's roles in brain and behavior. His interests, in this regard, ranged from its traditionally-accepted roles in hydromineral balance, to its less-appreciated functions in stress responses and energy metabolism. Here we review the current understanding of the role of the RAS in the regulation of metabolism. In particular, the opposing actions of the RAS within adipose tissue vs. its actions within the brain are discussed.

Intracerebroventricular tempol administration in older rats reduces oxidative stress in the hypothalamus but does not change STAT3 signalling or SIRT1/AMPK pathway.

Hypothalamic inflammation and increased oxidative stress are believed to be mechanisms that contribute to obesity. 4-Hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (tempol), a free radical scavenger, has been shown to reduce inflammation and oxidative stress. We hypothesized that brain infusion of tempol would reduce oxidative stress, and thus would reduce food intake and body weight and improve body composition in rats with age-related obesity and known elevated oxidative stress. Furthermore, we predicted an associated increase in markers of leptin signalling, including the silent mating type information regulator 2 homolog 1 (SIRT1)/5'AMP-activated protein kinase (AMPK) pathway and the signal transducer and activator of transcription 3 (STAT3) pathway. For this purpose, osmotic minipumps were placed in the intracerebroventricular region of young (3 months) and aged (23 months) male Fischer 344 x Brown Norway rats for the continuous infusion of tempol or vehicle for 2 weeks. Tempol significantly decreased (p < 0.01) nicotinamide adenine dinucleotide phosphate oxidase activity in the hypothalamus but failed to reduce food intake or weight gain and did not alter body composition. SIRT1 activity and Acetyl p53 were decreased and phosphorylation of AMPK was increased with age, but they were unchanged with tempol. Basal phosphorylation of STAT3 was unchanged with age or tempol. These results indicate that tempol decreases oxidative stress but fails to alter feeding behaviour, body weight, or body composition. Moreover, tempol does not modulate the SIRT1/AMPK/p53 pathway and does not change leptin signalling. Thus, a reduction in hypothalamic oxidative stress is not sufficient to reverse age-related obesity.

Therapeutic potential of adipose stem cell-derived conditioned medium against pulmonary hypertension and lung fibrosis.

BACKGROUND AND PURPOSE: Pulmonary hypertension (PH) and pulmonary fibrosis (PF) are life threatening cardiopulmonary diseases. Existing pharmacological interventions have failed to improve clinical outcomes or reduce disease-associated mortality. Emerging evidence suggests that stem cells offer an effective treatment approach against various pathological conditions. It has been proposed that their beneficial actions may be mediated via secretion of paracrine factors. Herein, we evaluated the therapeutic potential of conditioned media (CM) from adipose stem cells (ASCs) against experimental models of PH and PF. EXPERIMENTAL APPROACH: Monocrotaline (MCT) or bleomycin (Bleo) was injected into male Sprague-Dawley rats to induce PH or PF respectively. A subset of MCT and Bleo animals were treated with ASCs or CM. Echocardiographic and haemodynamic measurements were performed at the end of the study. Lung and heart tissues were harvested for RNA, protein and histological measurements. KEY RESULTS: CM treatment attenuated MCT-induced PH by improving pulmonary blood flow and inhibiting cardiac remodelling. Further, histological studies revealed that right ventricular fibrosis, pulmonary vessel wall thickness and pericyte distribution were significantly decreased by CM administration. Likewise, CM therapy arrested the progression of PF in the Bleo model by reducing collagen deposition. Elevated expression of markers associated with tissue remodelling and inflammation were significantly reduced in both PF and PH lungs. Similar results were obtained with ASCs administration. CONCLUSIONS AND IMPLICATIONS: Our study indicates that CM treatment is as effective as ASCs in treating PH and PF. These beneficial effects of CM may provide an innovative approach to treat cardiopulmonary disorders.

Anorexic response to rapamycin does not appear to involve a central mechanism.

The authors have previously demonstrated that a low and intermittent peripheral dose of rapamycin (1 mg/kg three times/week) to rats inhibited mTORC1 signalling, but avoided the hyperlipidemia and diabetes-like syndrome associated with higher doses of rapamycin. The dosing regimen reduced food intake, body weight, adiposity, serum leptin and triglycerides. mTORC1 signalling was inhibited in both liver and hypothalamus, suggesting some of the actions, in particular the decrease in food intake, may be the results of a central mechanism. To test this hypothesis, rapamycin (30 µg/day for 4 weeks) was infused into 23-25-month-old F344xBN rats by intracerebroventricular (icv) mini pumps. Our results demonstrated that central infusion did not alter food intake or body weight, although there was a tendency for a decrease in body weight towards the end of the study. mTORC1 signalling, evidenced by decreased phosphorylation of S6 protein at end of 4 weeks, was not activated in liver, hypothalamus or hindbrain. Fat and lean mass, sum of white adipose tissues, brown adipose tissue, serum glucose, insulin and leptin levels remained unchanged. Thus, these data suggest that the anorexic and body weight responses evident with peripheral rapamycin are not the result of direct central action. The tendency for decreased body weight towards the end of study, suggests that there is either a slow transport of centrally administered rapamycin into the periphery, or that there is delayed action of rapamycin at sites in the brain.

Onset of leptin resistance shows temporal differences related to dose or pulsed treatment.

Leptin administration results in leptin resistance presenting a significant barrier to therapeutic use of leptin. Consequently, we examined two hypotheses. The first examined the relationship between leptin dose and development of physiological and biochemical signs of leptin resistance. We hypothesized lower doses of leptin would produce proportional reductions in body weight without the adverse leptin-induced leptin resistance. The second compared pulsed central leptin infusion to continuous leptin infusion. We hypothesized that pulsed infusion at specific times of the day would evoke favorable body weight reductions while tempering the development of leptin-induced leptin resistance. The first experiment examined leptin responsiveness, including food intake, body weight and hypothalamic STAT3 phosphorylation to increasing doses of viral gene delivery of leptin. Varying the dose proved inconsequential with respect to long-term therapy and demonstrated proportional development of leptin resistance. The second experiment examined leptin responsiveness to pulsed central leptin infusion, comparing pulsed versus constant infusion of 3µg/day leptin or a 2h morning versus a 2h evening pulsed leptin infusion. Pulsed delivery of the supramaximal dose of 3µg/day was not different than constant delivery. Morning pulsed infusion of the submaximal dose of 0.25µg reduces food intake only over subsequent immediate meal period and was associated with body weight reductions, but results in cellular leptin resistance. Evening pulsed infusion did not decrease food intake but reduces body weight and maintains full leptin signaling. The positive benefit for pulsed delivery remains speculative, yet potentially may provide an alternative mode of leptin therapy.

Failed caudal block due to physiologic changes associated with a cerebrospinal fluid leak: a case report.

PURPOSE: The sum of the volumes of brain tissue, cerebrospinal fluid (CSF), and intracranial blood remain constant. This tenet of the Monroe-Kellie hypothesis is most often considered in the setting of intracranial hypertension, but it can also be applied in the setting of CSF volume depletion. We used this hypothesis to explain a case of failed caudal block in a patient with an iatrogenic CSF leak. CLINICAL FEATURES: A one-month-old baby (3 kg) born at 35 weeks' gestation presented for right inguinal hernia repair. His past medical history was significant for arthrogryposis (congenital joint contractures in two or more areas of the body) as well as ongoing apneic episodes that required continuous positive airway pressure therapy and neonatal intensive care. An ultrasound confirmed caudal block was completed and within five minutes of the procedure, the patient's heart rate increased, with an accompanying slight increase in T-wave amplitude. Pinch tests revealed anesthesia to the feet bilaterally but insufficient anesthesia to the abdomen. The surgery was delayed but successfully completed under general anesthesia the following week. Magnetic resonance imaging of the brain and spine following the surgery showed a significant CSF leak with engorgement of the epidural venous plexus along the entire spine. These findings were consistent with a CSF leak likely secondary to a prior lumbar puncture (at age 13 days) that was part of the investigation of his respiratory issues. CONCLUSIONS: The possible mechanism of this failed caudal block was high systemic absorption of anesthetic given the epidural venous plexus engorgement thus leaving less anesthetic acting within the CSF and on the exiting spinal nerves. Decreased CSF flow in the thecal sac might also have contributed, as might dilution of the remaining local anesthetic caused by large amounts of leaking CSF within the epidural space.

Associations between anthropometric characteristics, physical activity, and breast cancer risk in a Canadian cohort.

Obesity, physical inactivity, and sedentary behavior, concomitants of the modern environment, are potentially modifiable breast cancer risk factors. This study investigated the association of anthropometric measurements, physical activity and sedentary behavior, with the risk of incident, invasive breast cancer using a prospective cohort of women enrolled in the Canadian Study of Diet, Lifestyle and Health. Using a case-cohort design, an age-stratified subcohort of 3,320 women was created from 39,532 female participants who returned completed self-administered lifestyle and dietary questionnaires at baseline. A total of 1,097 incident breast cancer cases were identified from the entire cohort via linkage to the Canadian Cancer Registry. Cox regression models, modified to account for the case-cohort design, were used to estimate hazard ratios (HR) and 95 % confidence intervals (CI) for the association between anthropometric characteristics, physical activity, and the risk of breast cancer. Weight gain as an adult was positively associated with risk of post-menopausal breast cancer, with a 6 % increase in risk for every 5 kg gained since age 20 (HR 1.06; 95 % CI 1.01-1.11). Women who exercised more than 30.9 metabolic equivalent task (MET) hours per week had a 21 % decreased risk of breast cancer compared to women who exercised less than 3 MET hours per week (HR  0.79; 95 % CI 0.62-1.00), most evident in pre-menopausal women (HR  0.62; 95 % CI 0.43-0.90). As obesity reaches epidemic proportions and sedentary lifestyles have become more prevalent in modern populations, programs targeting adult weight gain and promoting physical activity may be beneficial with respect to reducing breast cancer morbidity.

Diminazene attenuates pulmonary hypertension and improves angiogenic progenitor cell functions in experimental models.

RATIONALE: Studies have demonstrated that angiotensin-converting enzyme 2 (ACE2) plays a protective role against lung diseases, including pulmonary hypertension (PH). Recently, an antitrypanosomal drug, diminazene aceturate (DIZE), was shown to exert an "off-target" effect of enhancing the enzymatic activity of ACE2 in vitro. OBJECTIVES: To evaluate the pharmacological actions of DIZE in experimental models of PH. METHODS: PH was induced in male Sprague Dawley rats by monocrotaline, hypoxia, or bleomycin challenge. Subsets of animals were simultaneously treated with DIZE. In a separate set of experiments, DIZE was administered after 3 weeks of PH induction to determine whether the drug could reverse PH. MEASUREMENTS AND MAIN RESULTS: DIZE treatment significantly prevented the development of PH in all of the animal models studied. The protective effects were associated with an increase in the vasoprotective axis of the lung renin-angiotensin system, decreased inflammatory cytokines, improved pulmonary vasoreactivity, and enhanced cardiac function. These beneficial effects were abolished by C-16, an ACE2 inhibitor. Initiation of DIZE treatment after the induction of PH arrested disease progression. Endothelial dysfunction represents a hallmark of PH pathophysiology, and growing evidence suggests that bone marrow-derived angiogenic progenitor cells contribute to endothelial homeostasis. We observed that angiogenic progenitor cells derived from the bone marrow of monocrotaline-challenged rats were dysfunctional and were repaired by DIZE treatment. Likewise, angiogenic progenitor cells isolated from patients with PH exhibited diminished migratory capacity toward the key chemoattractant stromal-derived factor 1α, which was corrected by in vitro DIZE treatment. CONCLUSIONS: Our results identify a therapeutic potential of DIZE in PH therapy.

Drugs, exercise, and the melanocortin-4 receptor-- different means, same ends: treating obesity.

As the percentage of obese humans expands, new options for weight loss are being explored. Body weight homeostasis is the result of a balance between energy intake (food) and expenditure (activity). A shift in homeostasis into a negative balance results in weight loss. Two potential options available for the management of body weight, as related to the melanocortin system, are exercise (increase energy expenditure) and drugs targeting the melanocortin-4 receptors for satiety.

Activin receptor signaling regulates prostatic epithelial cell adhesion and viability.

Mutational changes coupled with endocrine, paracrine, and/or autocrine signals regulate cell division during carcinogenesis. The hormone signals remain undefined, although the absolute requirement in vitro for fetal serum indicates the necessity for a fetal serum factor(s) in cell proliferation. Using prostatic cancer cell (PCC) lines as a model of cancer cell proliferation, we have identified the fetal serum component activin A and its signaling through the activin receptor type II (ActRII), as necessary, although not sufficient, for PCC proliferation. Activin A induced Smad2 phosphorylation and PCC proliferation, but only in the presence of fetal bovine serum (FBS). Conversely, activin A antibodies and inhibin A suppressed FBS-induced PCC proliferation confirming activin A as one of multiple serum components required for PCC proliferation. Basic fibroblast growth factor was subsequently shown to synergize activin A-induced PCC proliferation. Inhibition of ActRII signaling using a blocking antibody or antisense-P decreased mature ActRII expression, Smad2 phosphorylation, and the apparent viability of PCCs and neuroblastoma cells grown in FBS. Suppression of ActRII signaling in PCC and neuroblastoma cells did not induce apoptosis as indicated by the ratio of active/inactive caspase 3 but did correlate with increased cell detachment and ADAM-15 expression, a disintegrin whose expression is strongly correlated with prostatic metastasis. These findings indicate that ActRII signaling is required for PCC and neuroblastoma cell viability, with ActRII mediating cell fate via the regulation of cell adhesion. That ActRII signaling governs both cell viability and cell adhesion has important implications for developing therapeutic strategies to regulate cancer growth and metastasis.