Regulator of G-protein Signaling 14 Knockout (RGS14 KO) mice exhibit enhanced exercise capacity and health span, however the contribution of the gut microbiota to this phenotype remains unclear. This study integrated long-read rRNA operon amplicon sequencing and metabolomics to first determine how microbial composition and tissue metabolite profiles differ between RGS14 KO and their wild-type littermates. Next, we investigated how administration of antibiotics to perturb the gut microbiota may affect the RGS14 KO phenotype. Prior to antibiotic treatment (ABX), RGS14 KO mice outperformed WT littermates in maximal running distance and work performed, accompanied by elevated skeletal muscle citrate synthase, complex IV activity, and nitric oxide production. One week of ABX significantly reduced exercise capacity in both genotypes and markedly suppressed mitochondrial activity in RGS14 KO skeletal muscle. Gut microbiota profiling revealed similar phylum-level structure between genotypes but distinct species- and strain-level signatures. Metabolomics of brown adipose tissue (BAT) and quadriceps identified genotype-specific metabolic programs that were disrupted by ABX, including pathways related to amino acid metabolism, nucleotide turnover, and mitochondrial energetics. Collectively, these findings demonstrate that RGS14 KO mice harbor unique microbial and metabolic networks that support enhanced thermogenesis and exercise performance, and that microbiota depletion eliminates these advantages. This work establishes a mechanistic foundation connecting the gut microbiota to BAT and skeletal muscle metabolism, highlighting potential microbiome-targeted strategies to improve metabolic health and physical performance.

While human lifespan has increased dramatically over the past century, the extension of healthspan, the period free of chronic age-related disease, has lagged behind. Blood flow and angiogenesis are significantly reduced in aging humans, playing a crucial role in mediating cardiovascular disease and heart failure - major causes of reduced lifespan. However, these mechanisms have not been studied as extensively as cellular and molecular mechanisms in animal models. Healthful aging, due to angiogenesis and improved blood flow, is the focus of this review. Here we considered 25 rodent models of healthful longevity. Seven of these had direct evidence of improved blood flow and angiogenesis contributing to enhanced exercise, preserved organ function and resistance to ischemic injury and heart failure. Four others exhibited mixed results, but did not show clearly improved blood flow and angiogenesis Fourteen models did not examine these mechanisms. The mechanisms mediating the improved angiogenesis and, as a result enhanced blood flow, include not only vascular growth hormones and mitochondrial protection, but also a role for a less well studied factor, namely brown adipose tissue (BAT). For example, a recently studied rodent model, the Regulator of G Protein Signaling 14 knockout mouse, exhibited a marked increase in angiogenesis and improved blood flow through a BAT mechanism, i.e., when BAT was removed, blood flow and angiogenesis were no longer improved, but when it was transplanted into wild type mice, blood flow and angiogenesis were enhanced. Given the potential importance of angiogenesis and improved blood flow, these factors need to be considered for future healthful longevity therapeutic translation.

The Regulator of G Protein Signaling 14 (RGS14) knockout (KO) mouse is a model of healthful longevity, i.e., its lifespan is prolonged and demonstrates enhanced exercise performance and protection against heart disease and hypertension. In this investigation, we found the RGS14 KO mouse is also protected against obesity and glucose intolerance by promoting a low white adipose tissue (WAT) phenotype with increased brown adipose tissue (BAT). This was confirmed by lower body weight, lower white adipocyte size, increased metabolism and improved glucose tolerance and insulin sensitivity. Upon examination of the white adipose tissue, RGS14 KO exhibited increased expression of “beiging” genes as well as significant increase in Uncoupling protein-1 (UCP-1) expression. The mechanism behind this protection was due to its unique brown adipose tissue. This was determined by BAT transplantation, which led to a reversal of phenotype, such that RGS14 BAT recipients developed protection similar to intact RGS14 KO mice, and the RGS14 KO BAT donors lost their protection. Thus, two novel mechanisms mediating obesity and glucose intolerance were found, i.e., inhibition of RGS14 and its BAT.

Adenylyl cyclase 5 knockout (AC5 KO) is a healthful longevity model; not only do the AC5 KO mice live a third longer than wild-type (WT) mice, but they are also protected against obesity, diabetes, heart failure, and exercise intolerance, mediated by anti-apoptosis, cell survival, myocardial biogenesis, and anti-oxidative stress mechanisms. To translate these salutary effects to the clinics, we developed a drug, C90, which recapitulates the AC5 KO model of healthful longevity. We then examined its effects on glucose tolerance and exercise capacity. C90 (30 mg/kg/day) or vehicle was chronically administered to age-matched C57BL/6 mice via an osmotic pump. The WT mice receiving C90 exhibited improved glucose tolerance, following glucose i.v. injection, when compared to the vehicle. Furthermore, the C90-treated mice had a lower fasting glucose level when compared to the vehicle-treated mice (113 ± 6.5 mg/dL vs. 129 ± 4.2 mg/dL, p < 0.05). Additionally, the WT group that received C90 exhibited greater exercise capacity, reflected by longer running distance (384 ± 27 m vs. 253 ± 16 m, p < 0.05) and greater work to exhaustion (18.1 ± 1.5 J vs. 12.4 ± 0.7 J, p < 0.05) than mice receiving vehicle. In view of these findings, C90 is an excellent candidate for clinical development as an effective pharmacological treatment for glucose intolerance and enhancing exercise performance.

There are two major subtypes of adipose tissue, i.e., white adipose tissue (WAT) and brown adipose tissue (BAT). It has been known for a long time that WAT mediates obesity and impairs healthful longevity. More recently, interest has focused on BAT, which, unlike WAT, actually augments healthful aging. The goal of this review is to examine the role of BAT in mediating healthful longevity. A major role for BAT and its related beige adipose tissue is thermogenesis, as a mechanism to maintain body temperature by producing heat through uncoupling protein 1 (UCP1) or through UCP1-independent thermogenic pathways. Our hypothesis is that healthful longevity is, in part, mediated by BAT. BAT protects against the major causes of impaired healthful longevity, i.e., obesity, diabetes, cardiovascular disorders, cancer, Alzheimer’s disease, reduced exercise tolerance, and impaired blood flow. Several genetically engineered mouse models have shown that BAT enhances healthful aging and that their BAT is more potent than wild-type (WT) BAT. For example, when BAT, which increases longevity and exercise performance in mice with disruption of the regulator of G protein signaling 14 (RGS14), is transplanted to WT mice, their exercise capacity is enhanced at 3 days after BAT transplantation, whereas BAT transplantation from WT to WT mice also resulted in increased exercise performance, but only at 8 weeks after transplantation. In view of the ability of BAT to mediate healthful longevity, it is likely that a pharmaceutical analog of BAT will become a novel therapeutic modality.

The Gut Microbiota and Metabolome and Brown Adipose Tissue Regulate the Enhanced Exercise Capacity in Mice with Disruption of the Regulator of G protein Signaling 14 (RGS14) Candace R. Longoria, Olufunmilola Ibironke, Lee J. Kerkhof, Marko Oydanich, Xiaoyang Su, Eric Chiles, Dorothy E. Vatner, Stephen F. Vatner, Sara C. Campbell, FACSM.Rutgers, The State University of New Jersey Disruption of the Regulator of G Protein Signaling 14 (RGS14 (knockout) KO) results in a mouse model of healthful longevity with enhanced exercise capacity. Running distance and work to exhaustion are increased by 60±9% and 54±6% respectively in the RGS14 KO mouse compared to wild type littermates (WTL). Our hypothesis was that the enhanced exercise capacity was mediated by brown adipose tissue (BAT), which was confirmed by BAT transplants from RGS14 KO mice to WTL, resulting in a reversal of phenotype with the RGS14 KO mice losing the enhanced exercise capacity and WTL gaining the enhanced exercise capacity. We further hypothesized that the mechanism mediating the enhanced exercise capacity in RGS14 KO mice involved the gut microbiota and metabolome. The gut microbiota is linked to BAT, but the mechanisms and microbes facilitating BAT function remain largely unknown. Twenty-four mice were used to identify gut microbes by ribosomal operon profiling and metabolites in BAT samples at baseline. Bacterial differential expression analysis (via DESeq2) showed significant bacterial community differences between wild-type (WT) and RGS14 KO mice. Specifically, five bacterial strains ( Acutalibacter muris KB18, Ureaplasma urealyticum 132, Ureaplasma parvum ATCC 33697, Ureaplasma parvum, and Mucispirillum schaedleri ASF457) were present in RGS14 KO mice and not in WT. RGS14 KO mice also housed two distinctive strains of A. muciniphilia (BIOML-A22 and A. muciniphilia AN78). Eleven metabolites were significantly higher in RGS14 KO BAT samples compared to WT, with significant metabolic pathways, which in turn, are related to mechanisms mediating enhanced exercise capacity. We then examined the effects of antibiotic treatment (ABX) in 8 mice. Following 1 week of ABX, the bacterial strains that were increased in RGS14 KO mice were no longer elevated and the enhanced exercise capacity in RGS14 KO mice was no longer elevated compared to WTL. Furthermore, 6 of the 7 metabolites related to glucose and amino acid metabolism were no longer increased in RGS14 KO BAT compared to WTL. Taken together, these studies show that RGS14 KO BAT, associated with specific microbes and metabolites known to be involved with BAT, mediate the increased metabolic pathways that are associated with enhanced exercise capacity in RGS14 KO mice. In conclusion, the gut microbiota appears to be linked to RGS14 KO BAT function, which mediates enhanced exercise capacity in RGS14 KO mice. ONR Grant #826640 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Enhanced exercise capacity is not only a feature of healthful aging, but also a therapy for aging patients and patients with cardiovascular disease. Disruption of the Regulator of G Protein Signaling 14 (RGS14) in mice extends healthful lifespan, mediated by increased brown adipose tissue (BAT). Accordingly, we determined whether RGS14 knockout (KO) mice exhibit enhanced exercise capacity and the role of BAT in mediating exercise capacity. Exercise was performed on a treadmill and exercise capacity was assessed by maximal running distance and work to exhaustion. Exercise capacity was measured in RGS14 KO mice and their wild types (WT), and also in WT mice with BAT transplantation from RGS14 KO mice or from other WT mice. RGS14 KO mice demonstrated 160 ± 9% increased maximal running distance and 154 ± 6% increased work to exhaustion, compared to WT mice. RGS14 KO BAT transplantation to WT mice, resulted in a reversal of phenotype, with the WT mice receiving the BAT transplant from RGS14 KO mice demonstrating 151 ± 5% increased maximal running distance and 158 ± 7% increased work to exhaustion, at three days after BAT transplantation, compared to RGS14 KO donors. BAT transplantation from WT to WT mice also resulted in increased exercise performance, but not at 3 days, but only at 8 weeks after transplantation. The BAT induced enhanced exercise capacity was mediated by (1) mitochondrial biogenesis and SIRT3; (2) antioxidant defense and the MEK/ERK pathway, and increased hindlimb perfusion. Thus, BAT mediates enhanced exercise capacity, a mechanism more powerful with RGS14 disruption.

ABSTRACT The gut microbiota is critical to host metabolism and is influenced by many factors, including host genotype, diet, and exercise training. Purpose We investigated the effects of gut microbes, and the mechanisms mediating the enhanced exercise performance induced by exercise training, i.e., skeletal muscle blood flow, and mitochondrial biogenesis and oxidative function in male mice. Methods All mice received a graded exercise test before (PRE) and after exercise training via forced treadmill running at 60% to 70% of maximal running capacity 5 d·wk −1 for 5 wk (POST). To examine the role of the gut microbes, the graded exercise was repeated after 7 d of access to antibiotic (ABX)-treated water, used to eliminate gut microbes. Peripheral blood flow, mitochondrial oxidative capacity, and markers of mitochondrial biogenesis were collected at each time point. Results Exercise training led to increases of 60% ± 13% in maximal running distance and 63% ± 11% work to exhaustion ( P < 0.001). These increases were abolished after ABX ( P < 0.001). Exercise training increased hindlimb blood flow and markers of mitochondrial biogenesis and oxidative function, including AMP-activated protein kinase, sirtuin-1, PGC-1α citrate synthase, complex IV, and nitric oxide, all of which were also abolished by ABX treatment. Conclusions Our results support the concept that gut microbiota mediate enhanced exercise capacity after exercise training and the mechanisms responsible, i.e., hindlimb blood flow, mitochondrial biogenesis, and metabolic profile. Finally, results of this study emphasize the need to fully examine the impact of prescribing ABX to athletes during their training regimens and how this may affect their performance.

The gut microbiota is linked to brown adipose tissue (BAT), but the mechanisms and microbes facilitating BAT production or function are unknown. A novel mouse model containing a gene knock-out of regulator of G protein signaling 14 (RGS14 KO) has increased BAT. Our early studies found distinct microbes in RGS14 KO mice and BAT-specific metabolites. PURPOSE: To identify key gut microbial species and uncover BAT-specific metabolites in RGS14 KO mice. Further, we aim to identify and associate metabolites produced in specific tissue samples with these key gut microbes. METHODS: Twenty-two mice (N = 13 RGS14 KO, N = 9 Wild type (WT)) were used to identify predominant microbes and metabolites. Gut microbiota profiles were obtained by sequencing bacterial ribosomal operons. Metabolomics used ultra-high performance liquid chromatography to evaluate polar and nonpolar untargeted metabolites in fecal, cecal, brain, and BAT samples. Microbiome analysis used Kulczynski distance to compare WT to RGS14 KO reads in two-dimensional non-metric multidimensional scaling (NMDS) plots. Two-tailed t-tests were used to compare WT and RGS14 KO metabolite means (p < 0.05). MetaboAnalyst 5.0 was used to identify significant metabolite pathways in tissue samples and generate pathway plots. RESULTS: Approximately 500 k rRNA reads post QA/QC ((84% identify; >1000 bp alignment) were obtained from all samples by MegaBlast. NMDS plots showed significant bacterial community differences (Genus: p = 0.035; species: p = 0.028; strain: p = 0.037) between WT and RGS14 KO mice. Specifically, RGS14 KO mice housed two unique strains of Akkermansia muciniphilia (A. muciniphilia BIOML-A22 and A. muciniphilia AN78) while WT animals contained A. muciniphilia EB-AMDK-1. Untargeted metabolomics identified 82 significantly different (p < 0.05) unique metabolites were between RGS14 KO and WT mice in one of the four samples. Specifically, RGS14 KO animals had significantly higher levels of G6P, glycyl-l-proline, glyercophosphocholine, isoleucine, pipecolic acid, thymidine, UDP-D-glucose, malate, leucic acid, NADP+, and guanosine in BAT compared to WT animals. CONCLUSION: The gut microbiome differs between RGS14 KO and WT mice from genus to strain level. Unique metabolites found in RGS14 KO BAT may be linked to BAT function. Supported by ONR Grant 826640

Disruption of adenylyl cyclase 5 (AC5 KO) is a healthful longevity model; not only do the AC5 KO mice live a third longer than wild type (WT) mice, but are also protected against heart failure, obesity and diabetes and exercise intolerance. To translate to the clinics, we developed a new drug, C90, which inhibits AC5, and examined its effects on cardioprotection in pigs, exercise capacity and glucose tolerance in mice. C90 (30 mg/kg/day) or vehicle were chronically administered to age-matched C57/BL6 male mice via osmotic pump. After baseline exercise, the WT mice, all performing similarly, were divided into two groups; one that received C90 for 14 days and the other receiving vehicle for 14 days. After 14 days of C90 treatment, WT mice exhibited greater exercise capacity reflected by longer running distance (384 ± 27 m vs. 253 ± 16 m, p<0.05) and greater work to exhaustion (18.1 ± 1.5 J vs. 12.4 ± 0.7 J, p<0.05) than mice receiving vehicle. Sensitivity to glucose was measured using a glucose tolerance test in mice. Following 14-days treatment with C90 (30 mg/kg/day), the mice exhibited an overall improvement in glucose tolerance, measured as area under the curve (A.U.) for glucose levels following insulin injection, when compared to vehicle (6414 ± 890 A.U. vs. 9658 ± 1039 A.U., p<0.04). Furthermore, C90-treated mice had a lower fasting glucose level on a regular diet, when compared to vehicle (113 ± 6.5 mg/dl vs. 129 ± 4.2 mg/dl, p<0.05). The cardioprotective effects of C90 were previously demonstrated in mice. In the current study, we investigated the cardioprotective effects of C90 in a porcine model of ischemia/reperfusion (I/R). Ischemia was induced for 60 min coronary artery occlusion, followed by 3-hours reperfusion. C90 (1.2 mg/kg), infused 5 min following the start of the reperfusion led to a decreased infarct size/area at risk (INF/AAR) (21.6 ± 4.3% vs. 36.8 ± 2.9%, p<0.05) when compared to vehicle, with no difference between AAR/left ventricle between the C90 and vehicle groups. In view of its lower level of toxicity than other AC5 inhibitors, C90 is an excellent candidate for clinical development for pharmacological treatment of myocardial ischemia, glucose intolerance and exercise intolerance.

Female C57BL/6J wild-type (WT) mice (5 months old) exhibited greater maximal exercise capacity for running distance (489 ± 15 meters; n=6, p<0.05) than age-matched male WT mice (307 ± 17 m; n=8), as well as a 21% greater capacity for work to exhaustion. We hypothesized that these observed differences may be mediated by gut microbiota, as the sexes are known to have distinctly different microbiota. Predominant species in the male mice were found to be Faecalibacterium prausnitzii, Roseburia intestinalis and Allobaculum spp. while female mice had predominantly Parabacteroides goldstenii and Eubacterium coprostanoligenes. To determine if microbiota contribute to exercise tolerance, we administered antibiotic therapy (ABX) in drinking water to eliminate gut microbes. ABX eliminated the enhanced exercise tolerance of WT females. We then examined a model of enhanced exercise capacity -- Regulator of G Protein Signaling 14 (RGS14) knockout (KO) mice -- which exhibit greater maximal running distance (648 ± 38 m vs. 405 ± 21 m; p<0.05) than age matched WT mice, as well as a 53% increase in work to exhaustion (n=10/group). There is no difference in the enhanced exercise capacity of RGS14 KO mice between males and females. The greater exercise capacity in the RGS14 KO mice was also abolished by ABX. In conclusion, the gut microbiome appears to be a key factor in mediating exercise performance, since eliminating its action with chronic antibiotic therapy also eliminates the enhanced exercise performance in female vs male WT mice and in RGS14 KO mice of either sex.

The 'fight or flight' response to physiological stress involves sympathetic nervous system activation, catecholamine release and adrenergic receptor stimulation. In the heart, this induces positive inotropy, previously attributed to the β1-adrenergic receptor subtype. However, the role of the α1A-adrenergic receptor, which has been suggested to be protective in cardiac pathology, has not been investigated in the setting of physiological stress. To explore this, we developed a tamoxifen-inducible, cardiomyocyte-specific α1A-adrenergic receptor knock-down mouse model, challenged mice to four weeks of endurance swim training and assessed cardiac outcomes. With 4-OH tamoxifen treatment, expression of the α1A-adrenergic receptor was knocked down by 80-89%, without any compensatory changes in the expression of other adrenergic receptors, or changes to baseline cardiac structure and function. Swim training caused eccentric hypertrophy, regardless of genotype, demonstrated by an increase in heart weight/tibia length ratio (30% and 22% in vehicle- and tamoxifen-treated animals, respectively) and an increase in left ventricular end diastolic volume (30% and 24% in vehicle- and tamoxifen-treated animals, respectively) without any change in the wall thickness/chamber radius ratio. Consistent with physiological hypertrophy, there was no increase in fetal gene program (Myh7, Nppa, Nppb or Acta1) expression. In response to exercise-induced volume overload, stroke volume (39% and 30% in vehicle- and tamoxifen-treated animals, respectively), cardiac output/tibia length ratio (41% in vehicle-treated animals) and stroke work (61% and 33% in vehicle- and tamoxifen-treated animals, respectively) increased, regardless of genotype. These findings demonstrate that cardiomyocyte α1A-adrenergic receptors are not necessary for cardiac adaptation to endurance exercise stress and their acute ablation is not deleterious.

The goal of this review is to provide further understanding of increased vascular stiffness with aging, and how it contributes to the adverse effects of major human diseases. Differences in stiffness down the aortic tree are discussed, a topic requiring further research, because most prior work only examined one location in the aorta. It is also important to understand the divergent effects of increased aortic stiffness between males and females, principally due to the protective role of female sex hormones prior to menopause. Another goal is to review human and non-human primate data and contrast them with data in rodents. This is particularly important for understanding sex differences in vascular stiffness with aging as well as the changes in vascular stiffness before and after menopause in females, as this is controversial. This area of research necessitates studies in humans and non-human primates, since rodents do not go through menopause. The most important mechanism studied as a cause of age-related increases in vascular stiffness is an alteration in the vascular extracellular matrix resulting from an increase in collagen and decrease in elastin. However, there are other mechanisms mediating increased vascular stiffness, such as collagen and elastin disarray, calcium deposition, endothelial dysfunction, and the number of vascular smooth muscle cells (VSMCs). Populations with increased longevity, who live in areas called “Blue Zones,” are also discussed as they provide additional insights into mechanisms that protect against age-related increases in vascular stiffness. Such increases in vascular stiffness are important in mediating the adverse effects of major cardiovascular diseases, including atherosclerosis, hypertension and diabetes, but require further research into their mechanisms and treatment.

The Regulator of G Protein Signaling 14 knockout (RGS14 KO) mouse strain has a unique brown adipose tissue (BAT) mechanism mediating its phenotype of healthful longevity and improved exercise performance. RGS14 KO mice demonstrated a 51 ± 8% increase in treadmill running distance before exhaustion and a 44 ± 7% increase in work to exhaustion compared to their wild type littermates (WTLs). Three days after BAT transplantation from RGS14 KO mice to WTL mice, the RGS14 KO BAT donor mice lost their enhanced exercise capacity, whereas it was gained in the WTL BAT recipients: their running distance and work to exhaustion rose by 46 ± 5% and 52 ± 7%, respectively. In contrast, when BAT was transplanted to WTL mice from other WTL mice, exercise capacity did not increase at 3 days after transplantation, but was only seen after 2 months post-transplantation. Based on these observations, our hypothesis was that the unique characteristics of RGS14 KO BAT, in inducing enhanced exercise capacity upon transplantation, are mediated by novel gene upregulation within the BAT, as well as potential interactions between the BAT and the microbiome. We found that RGS14 KO mice harbor two unique, health-beneficial strains of Akkermansia muciniphilia ( A. muciniphilia BIOML-A22 and A. muciniphilia AN78) in their gut and their BAT has a number of novel genes upregulated, including Lnpep (leucyl/cystinyl aminopeptidase), TFAM (transcription factor A, mitochondrial), and Lncbate10, the latter being a critical regulator of BAT differentiation. To address directly the role of the microbiome, the mice were treated with antibiotics for 1 week. Although WTL exercise capacity was not significantly different before and after antibiotic-induced microbiota clearance, the RGS14 KO mice lost their enhanced exercise capacity after antibiotic treatment: RGS14 KO running distance fell by 35 ± 7%, and work to exhaustion fell by 41 ± 7%. Thus, RGS14 KO BAT engages changes to resident commensal microbiota that are beneficial to exercise capacity and therefore represents a potential (and novel) therapeutic modality for improving exercise performance and for creating healthful longevity.

The goal of this investigation was to compare the effects of chronic (4 wk) transverse aortic constriction (TAC) in Sprague-Dawley rats and C57BL/6J mice. TAC, after 1 day, induced similar left ventricular (LV) pressure gradients in both rats ( n = 7) and mice ( n = 7) (113 ± 5.4 vs. 103 ± 11.5 mmHg), and after 4 wk, the percent increase in LV hypertrophy, as reflected by LV/tibial length (51% vs 49%), was similar in rats ( n = 12) and mice ( n = 12). After 4 wk of TAC, LV systolic and diastolic function were preserved in TAC rats. In contrast, in TAC mice, LV ejection fraction decreased by 31% compared with sham, along with increases in LV end-diastolic pressure (153%) and LV systolic wall stress (86%). Angiogenesis, as reflected by Ki67 staining of capillaries, increased more in rats ( n = 6) than in mice ( n = 6; 10 ± 2 vs. 6 ± 1 Ki67-positive cells/field). Myocardial blood flow fell by 55% and coronary reserve by 28% in mice with TAC ( n = 4), but they were preserved in rats ( n = 4). Myogenesis, as reflected by c-kit-positive myocytes staining positively for troponin I, is another mechanism that can confer protection after TAC. However, the c-kit-positive cells in rats with TAC were all negative for troponin I, indicating the absence of myogenesis. Thus, rats showed relative tolerance to severe pressure overload compared with mice, with mechanisms involving angiogenesis but not myogenesis.

Whereas collagen and elastin content have been widely studied as mechanisms for mediating increased aortic stiffness with aging, collagen and elastin disarray has been less well studied, not only in all aging models, but most particularly in aging pre‐menopausal females. The current investigation compared collagen and elastin disarray in the aorta in aging, 24±1 years old, premenopausal female monkeys (M. Fascicularis and M. Mulatta) with disarray in young female monkeys (6 ± 1 years old). The non‐human primate model is unique for these studies, since most other aging animal models do not go through menopause. Collagen/elastin ratio and disarray were increased in the old, pre‐menopausal females compared to the young females in the thoracic aorta, but even more in the abdominal aorta, and the most in the iliac artery. For example, compared to values in the thoracic aorta of young females, the collagen/elastin ratio increased in the thoracic aorta of old female monkeys by 169%, and by 397% in the iliac artery of the old females. Compared to values in the thoracic aorta of young females, the disarray of elastin fibers increased by 106% in the thoracic aorta of the old female monkeys and by 350% in the iliac artery of the old female monkeys. Compared to values in the thoracic aorta of young females, the disarray of collagen fibers increased by 148% in the thoracic aorta of the old females and by 378% in the iliac artery of the old female monkeys. Compared to values in the thoracic aorta of young females, the number of breaks in elastin fibers increased by 158% in the thoracic aorta of the old females and by 883% in the iliac artery of the old female monkeys. Compared to values in the thoracic aorta of young females, the number of breaks in collagen fibers increased by 105% in the thoracic aorta of the old females and by 390% in the iliac artery of the old female monkeys. Thus, old pre‐menopausal female monkeys exhibit enhanced mechanisms of vascular stiffness. These mechanisms were increased in the thoracic aorta, but significantly more increased in the iliac artery.Support or Funding InformationStudy supported by National Institutes of Health grants R21 AG053514; R01 HL119464; R01 HL137405; R01 HL102472; R01 HL106511; R01 HL130848; R01 HL137368; UL1TR003017;

Increased brown adipose tissue results in improved metabolism and protection against cold exposure in humans. The goal of this investigation was to determine if increased brown adipose tissue can improve exercise performance and protect against glucose intolerance. This was accomplished by surgical removal of interscapular brown adipose tissue from c57 wild type mice and transplanting it to other c57 wild type mice. Following transplantation it was necessary to determine how long it would take for any changes to develop. 3 days following transplantation both recipients and donors were exercise tested using a treadmill. No differences were observed between recipients and donors in terms of both running distance (372 ± 14m vs. 377 ± 12m) and work to exhaustion (17.7 ± 1.0 J vs. 16.5 ± 1.4 J). However, at 8 weeks following brown adipose tissue transplantation, the recipient mice demonstrated enhanced exercise performance, p<0.05, in terms of running distance (507 ± 16m) and work to exhaustion (24.3 ± 1.4J), whereas exercise capacity did not change in brown adipose tissue donors. Indirect calorimetry was measured during exercise, with recipients exhibiting improved metabolism, p<0.05, resulting in 7% higher levels of peak oxygen consumption (VO2), 15% higher levels of peak carbon dioxide production (VCO2), and 9% higher levels of peak energy expenditure (EE). The improved exercise metabolism observed in the c57 recipients was accompanied by improved glucose tolerance. Following 8 weeks after brown adipose tissue transplantation, c57 recipients exhibited improved glucose tolerance as demonstrated by glucose tolerance test. Glucose (1g/kg), was administered IP and measurements of blood glucose were made at 30 minute intervals until blood glucose returned to baseline. Glucose tolerance was measured as the area under the curve, which was lower, p<0.05, in brown adipose tissue recipients (7515 ± 676 A.U.) as compared to c57 donors (11051 ± 1035 A.U.). Therefore, increased brown adipose tissue induces healthful aging, both in terms of enhanced exercise performance and improved metabolism resulting in protection against diabetes.

Our hypothesis is that Secreted Frizzled-Related Protein 2 (sFPR2) is an important mechanism mediating ischemic cardioprotection, since it is the most upregulated gene in the third window of ischemic preconditioning. One week after permanent coronary artery occlusion (CAO), sFRP2 TG mice exhibited a 49% higher LV ejection fraction and a 36% reduction in infarct size,p < 0.05, and reduced fibrosis in both adjacent and remote zones, along with an increase in collagen type III and a decrease in the collagen type I/III ratio compared with WTL. The ischemic cardioprotection was associated with increased angiogenesis and arteriogenesis, reflected by increased capillary and arteriolar proliferation in the ischemic zone, thereby preserving blood flow after CAO. The angiogenesis and arteriogenesis were mediated by cross talk between myocytes and endothelial cells. The mechanism for cardioprotection and angiogenesis/arteriogenesis did not involve a traditional vascular growth hormone, e.g., VEGF or FGF, but rather cTGF, and ATF6 through the stress signaling pathway. The ATF6 inhibitor, AEBSF, blocked the upregulation of cTGF and both the angiogenesis and arteriogenesis, resulting in abolition of the reduced infarct size and protection of cardiac function in the sFRP2 TG mouse following permanent CAO. sFRP2 is a novel mechanism to induce angiogenesis/arteriogenesis, mediated through the endoplasmatic reticulum (ER) stress signaling pathway, ATF6 and cTGF, which protects the heart from myocardial ischemia.