bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex Differences in the Sympathetic Restraint of Skeletal Muscle Blood Flow in the Human Leg Vasculature
Authors: Bunsawat Kanokwan , Ratchford Stephen M. , Clifton Heather L. , Theisen Jeremy K. , Barrett‐O'Keefe Zachary , Broxterman Ryan M. , Gifford Jayson R. , Hydren Jay , Rossman Matthew J. , Ives Stephen J. , Trinity Joel D. , Witman Melissa A.H. , Garten Ryan S. , Morgan David E. , Nelson Ashley D. , Richardson Russell S. , Wray D. Walter
Published: June 2021

Background

The sympathetic nervous system plays an important role in regulating skeletal muscle blood flow at rest and during exercise. Previous studies have identified sex differences in resting muscle sympathetic nerve activity1 and forearm alpha‐adrenergic receptor sensitivity.2 However, whether sympathetic restraint of limb blood flow differs between sexes, and the degree to which this restraint persists during dynamic exercise, is not well understood.

Methods

In four young men (28±2 yrs; 26±2 kg/m2) and six young women (24±2 yrs; 23±1 kg/m2), we evaluated changes in leg blood flow (LBF, Doppler ultrasound), mean arterial blood pressure (MAP, indwelling femoral artery catheter), and leg vascular conductance (LVC) before and after intra‐arterial infusion of phentolamine (PHEN, non‐selective alpha‐adrenergic antagonist, 5 μg/dL/min) at rest and during small muscle mass knee‐extensor (KE) exercise (15W). Influences from beta‐adrenergic receptors were blocked by intravenous administration of propranolol (0.07 mg/kg bolus).

Results

No sex differences in LBF, MAP, or LVC were observed at rest. Following PHEN administration, sex differences were evident for both the drug‐induced increase in resting LBF (+337±79 vs. +172±43 mL/min, p<0.05, men vs. women) and LVC (+3.69±1.04 vs. +1.97±0.45 mL/min/mmHg, men vs. women, p=0.06). During KE exercise, no sex differences were evident for LBF, MAP, or LVC prior to PHEN infusion, and drug administration provoked similar increases in LBF (+630±128 vs. +560±85 mL/min, men vs. women) and LVC (+7.2±1.5 vs. +6.9±1.6 mL/min/mmHg, men vs. women) between groups.

Conclusion

At rest, men demonstrate a larger increase in LBF and LVC in response to local alpha adrenergic receptor blockade via PHEN infusion, suggesting a greater degree of basal sympathetic vasoconstriction than their female counterparts. However, during exercise, similar increases in leg hemodynamics were observed between men and women following PHEN administration. Together, these data support the presence of a sex difference in the sympathetic restraint of resting limb blood flow that does not persist during moderate intensity exercise.

Support or Funding Information

This project is funded in part by the National Institutes of Health (HL118313) and the U.S. Department of Veterans Affairs (RX001697, RX001418, E6910R).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Sympathetic Baroreflex Sensitivity During Mental Stress in Humans With Chronic Anxiety
Authors: Holwerda Seth W. , Gremaud Allene L. , Luehrs Rachel E. , Fiedorowicz Jess G. , Abboud Francois M. , Pierce Gary L.
Published: June 2021

Elevated muscle sympathetic nerve activity (MSNA) is associated with the pathogenesis of hypertension and cardiac arrhythmias, and may be related to greater cardiovascular disease (CVD) risk among individuals with chronic anxiety. Augmented sympathetic responsiveness in chronic anxiety may potentially be attributed to alteration in sympathetic baroreflex control. We hypothesized that MSNA and its responsiveness to stress would be augmented in chronic anxiety, and that augmented MSNA responsiveness would be related to impaired sympathetic baroreflex sensitivity. Sympathetic baroreflex sensitivity was assessed by relating spontaneous changes in multi‐unit MSNA to beat‐to‐beat changes in diastolic blood pressure (DBP) using a weighted linear regression at rest (10 min) and during mental stress (MS, 4‐min mental arithmetic) in 18 individuals with moderate/high chronic anxiety (ANX, 6 men/12 women; 32±2 yrs; 27±2 kg/m2) who were nonsmokers and free of CVD, and in 18 healthy controls with low/no anxiety (CON, 8 men/10 women; 39±3 yrs; 30±1 kg/m2). Resting MSNA was not elevated among ANX compared to CON (MSNA burst incidence: ANX 29 ± 5 vs. CON 40 ± 4 bursts/100hb; Avg. relative MSNA burst amplitude: ANX 48 ± 1 vs. CON 47 ± 1 AU). Avg. relative MSNA burst amplitude in response to MS was significantly augmented among ANX compared to CON (ANX: 61 ± 2 vs. CON: 54 ± 2 AU, P=0.02), while % change in MSNA burst incidence was not significantly different between ANX and CON (ANX: 4 ± 7 vs. CON: 6 ± 7 bursts/100hb, P=0.86). Increases in avg. relative MSNA burst amplitude during MS were significantly correlated with trait anxiety score among all participants after adjusting for age, sex, and BMI (R=0.48, P=0.01). The slope between MSNA burst incidence and DBP was not different between ANX and CON at rest (ANX: −2.8 ± 0.6 vs. CON: −3.5 ± 0.5 bursts/100hb/mmHg−1, P=0.35), and was significantly reduced during MS (P=0.03) with no difference between ANX and CON (ANX: −2.2 ± 0.4 vs. CON: −2.3 ± 0.5 bursts/100hb/mmHg−1, P=0.42). The slope between total MSNA and diastolic BP was similar between ANX and CON at rest (ANX: −1.5 ± 0.3 vs. CON: −1.9 ± 0.3 AU/beat/mmHg−1, P=0.3) and unchanged (P=0.49) during MS (ANX: −1.5 ± 0.3 vs. CON: −1.5 vs. 0.3 AU/beat/mmHg−1, P=0.99). These preliminary findings demonstrate that individuals with chronic anxiety exhibit augmented increases in MSNA burst amplitude but not burst incidence to mental stress, and this alteration in the MSNA response to mental stress in chronic anxiety is not a result of impairment in sympathetic baroreflex sensitivity.

Support or Funding Information

AHA 17POST33440101, T32 HL07121 NHLBI (P01HL014388), U54 TR001356 and AHA (13DG143400012)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Epidural Spinal Cord Stimulation Acutely Reduces Efferent Postganglionic Sympathetic Nerve Activity in Humans
Authors: Holwerda Seth W. , Holland Marshall T. , Reddy Chandan G. , Pierce Gary L.
Published: June 2021

Evidence in clinical and animal studies demonstrates that epidural spinal cord stimulation (SCS) mimics the effects of sympathetic block or sympathectomy and increases peripheral blood flow. However, the extent to which SCS lowers sympathetic nerve activity in humans remains unclear because no studies have directly assessed muscle sympathetic nerve activity (MSNA) responses to SCS. We tested the hypothesis that acute SCS (60 min) at the lower thoracic spine would 1) lead to reduced MSNA in the peroneal nerve, and 2) increase blood flow in the legs, but not the arms. Twelve patients (54 ± 3 yrs, 5 men/7 women) that previously underwent surgical implantation of a SCS device for management of neuropathic pain were studied. Following 48 hours of no SCS, femoral and brachial artery blood flow was assessed using Doppler ultrasound at baseline and at 15, 30, 45, 60 min of SCS, and 15 min post SCS. MSNA was assessed using microneurography under the same conditions during a second visit (n=5). Femoral artery blood flow was significantly increased throughout SCS and 15 min post SCS (15 min: 26 ± 1%, 30 min: 32 ± 14%, 45 min: 30 ± 13%, 60 min: 26 ± 13%, 15 min post SCS: 40 ± 14% ml/min, P=0.02), but no change in brachial artery blood flow was observed (15 min: 4 ± 6%, 30 min: 5 ± 8%, 45 min: 5 ± 7%, 60 min: 7 ± 7% ml/min, 15 min post SCS: 6 ± 11% ml/min, P=0.86). MSNA was progressively reduced during SCS, reaching significance at 45 and 60 min, and returned toward baseline following SCS (15 min: −1 ± 6%, 30 min: −13 ± 4%, 45 min: −17 ± 6%, 60 min: −21 ± 7%, 15 min post SCS: −4 ± 5% bursts/100heartbeats, P=0.01). Similar results were observed for MSNA total activity (AU/min) (P<0.042). During measures of MSNA, self‐reported neuropathic pain was low at baseline and not significantly changed by SCS (scale 0–10; BL: 2.8 ± 0.8, 15 min: 1.7 ± 0.9, 30 min: 1.5 ± 1, 45 min: 1.7 ± 1, 60 min: 1.5 ± 1, P=0.07), suggesting that reductions in MSNA were SCS‐mediated and not primarily a result of pain relief. These preliminary results demonstrate proof of principle that acute lower thoracic SCS significantly reduces peroneal MSNA in humans.

Support or Funding Information

AHA 17POST33440101, T32 HL07121, NHLBI (P01HL014388), U54 TR001356 and AHA (13DG143400012)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Chronic chemogenetic activation of OVLT neurons alters body fluid homeostasis and sympathetically‐mediated hypertension
Authors: Stocker Sean D. , Farquhar William B. , Wenner Megan M.
Published: June 2021

The organum vascuolsum of the lamina terminalis (OVLT) contains a specialized group of neurons that can sense changes in extracellular NaCl concentrations to alter body fluid homeostasis and arterial blood pressure (ABP). Acute excitation of these neurons with hypertonic NaCl produces a sympathetically‐mediated increase in ABP. The purpose of the present study was to determine whether chronic activation of OVLT neurons produces hypertension. Rats were instrumented with telemetry devices and received an OVLT‐targeted injection of rAAV2‐hSyn‐HM4D(Gi)‐mCherry (3×1012 particles/mL, 50nL). Animals were returned to home cages to recover for 4 weeks with access to 0.1% NaCl chow and 0.9% NaCl drinking solution. After a 3‐day recording of baseline ABP and heart rate, clozapine‐N‐oxide was added to the 0.9% drinking solution for 7 days to produce a daily dose of ~3 mg/kg body weight. The concentration of the clozapine‐N‐oxide was adjusted daily to account for changes in fluid intake. Administration of clozapine‐N‐oxide to OVLT‐HM4D(Gi)‐expressing rats significantly increased 24‐h fluid intake from baseline to Day 7 (60±10 vs 178±29mL; n=4, P<0.01). Chronic activation of OVLT neurons significantly increased 24‐h mean ABP from baseline values versus Day 7 (97±2 vs 106±1 mmHg; n=4, P<0.05). Heart rate decreased from baseline values versus Day 7 (385±14 vs 330±26 bpm; n=4, P<0.05). Ganglionic blockade with hexamethonium (30 mg/kg, ip) produced a greater fall in mean ABP at Day 7 versus baseline values (baseline: −38±6 mmHg vs −53±5 mmHg; n=4, P<0.05). In addition, chronic activation of OVLT neurons increased 24‐h systolic blood pressure variability, calculated by the SD of systolic blood pressure, from baseline values versus Day 7 (9.1±0.4 vs 11.2±0.3 mmHg, P<0.05). Collectively, these observations suggest the chronic activation of OVLT neurons produces profound changes in body fluid homeostasis and cardiovascular regulation as reflected by 3x‐increase in fluid intake, a sympathetically‐mediated hypertension, and an increase in systolic blood pressure variability.

Support or Funding Information

NIH R01 113270 and 128388

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
AT1A Receptors on Vasopressin‐Producing Cells are Important for Vasopressin Secretion but not Blood Pressure Responses to Chronic Intracerebroventricular Angiotensin in Mice
Authors: Zhang Shao Y. , Sandgren Jeremy A. , Linggonegoro Danny W. , Usachev Andrew M. , Pearson Nicole A. , Grobe Justin L.
Published: June 2021

Vasopressin (AVP) plays an important role in cardiometabolic physiology by elevating blood pressure and water reabsorption. This hormone is produced in the magnocellular neurosecretory cells (MNCs) within the supraoptic nucleus (SON) and periventricular nucleus (PVN) of the hypothalamus. Angiotensin II (ANG) has been shown to act at AT1A receptors in the brain and cause AVP‐dependent elevations in blood pressure. Critically, the contribution of AT1A receptors specifically on AVP‐producing cells to blood pressure remains unclear. We hypothesized that AT1A receptor knockout only from AVP‐expressing cells would prevent blood pressure elevations in response to chronic intracerebroventricular (ICV) ANG infusion. Mice with AT1A knockout from AVP‐producing cells (AT1AAVP‐KO) were generated by breeding AVP‐Cre mice with AT1Aflox mice. Subcutaneous osmotic mini‐pumps were used to infuse artificial cerebrospinal fluid (aCSF) or ANG (50 ng/hr) into the lateral cerebral ventricle. Blood pressure was measured daily by tail‐cuff plethysmography for three weeks before and two weeks following implantation surgery. Water intake and urine output were measured using metabolic cages. Baseline systolic blood pressure (SBP) was indistinguishable among groups (Control aCSF 113±2, Control ANG 112±2, AT1AAVP‐KO aCSF 114±3, AT1AAVP‐KO ANG 113±2 mmHg; p=ns). ANG increased SBP similarly in control and KO mice (Control aCSF 107±3, Control ANG 121±2, AT1AAVP‐KO aCSF 111±2, AT1AAVP‐KO ANG 119±4 mmHg; ANG p<0.05, genotype p=ns, interaction p=ns). Water intake (Control aCSF 2.8±0.3, Control ANG 13.3±3.3, AT1AAVP‐KO aCSF 2.2±0.3, AT1AAVP‐KO ANG 11.3±2.9 mL/day; ANG p<0.05, genotype p=ns, interaction p=ns) and urine output (Control aCSF 0.7±0.2, Control ANG 7.7±2.6, AT1AAVP‐KO aCSF 0.4±0.1, AT1AAVP‐KO ANG 6.4±1.9 mg/day; ANG p<0.05, genotype p=ns, interaction p=ns) were also increased by ANG but not different between genotypes. Interestingly, urine copeptin was elevated by ANG in controls but not AT1AAVP‐KO mice (Control aCSF 27.6±6.1, Control ANG 137.9±35.6, AT1AAVP‐KO aCSF 78.3±15.7, AT1AAVP‐KO ANG 60.0±15.7 mL/day; ANG p<0.05, genotype p=ns, interaction p<0.05). For all studies, Control aCSF n=14, Control ANG n=7, AT1AAVP‐KO aCSF n=14, AT1AAVP‐KO ANG n=10. These data support the conclusion that AT1A receptors on AVP‐expressing cells are important for the control of AVP secretion in response to ICV ANG, but that this specific sub‐population of receptors are of minor importance for SBP responses to ICV ANG.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Identifying ‘angiotensin sensitive’ neurons in the lamina terminalis that coordinate endocrine, cardiovascular and behavioral responses mediating body fluid homeostasis
Authors: Krause Eric G. , Alleyne Amy R. , Cahill Karlena M. , Smeltzer Michael D. , Bruce Erin B. , Tan Yalun , Harden Scott W. , Frazier Charles J. , de Kloet Annette D.
Published: June 2021

Body fluid homeostasis is controlled by endocrine, cardiovascular and behavioral responses that maintain blood osmolality and perfusion pressure at optimal levels. Angiotensin type 1a receptors (AT1a) in the brain are known to coordinate these responses but the underlying neuronal circuits remain unclear. This study investigates the structure and function of AT1a neurons in the median preoptic nucleus (MnPO) and the organum vasculosum of the lamina terminalis (OVLT) to better understand their role in body fluid homeostasis. Using male mice that express Cre‐recombinase prior to the STOP codon of the AT1a gene (i.e., AT1a‐Cre mice), initial studies combined genetic reporting with in situ hybridization to reveal that neurons in the MnPO and OVLT that express AT1a are largely glutamatergic. Subsequently, AT1a‐Cre mice were delivered a Cre‐inducible adeno‐associated virus to induce expression of channelrhodopsin‐2 (ChR2) and enhanced yellow fluorescent protein (eYFP) specifically within AT1a neurons of the MnPO/OVLT. Neuroanatomical and in vitro electrophysiological studies revealed that AT1a neurons in the MnPO/OVLT send dense glutamatergic projections into the paraventricular nucleus of the hypothalamus that synapse onto vasopressin (AVP)‐synthesizing neurons. To evaluate the functionality of this connection, we optogenetically stimulated AT1a‐expressing neurons in the MnPO/OVLT and recorded cardiovascular parameters in anesthetized mice. Relative to control mice given virus that only expressed eYFP, 10 min of optogenetic stimulation robustly elevated systolic blood pressure in mice expressing ChR2. This effect was rapid in its onset (34 ± 9 vs. −2 ± 4 mmHg at 5 min, p < 0.05) but persisted for the entire 50 min of cardiovascular recording (45 ± 11 vs. −3 ± 7 mmHg at 50 min, p < 0.05). Intriguingly, optogenetic stimulation elicited a significant increase in Fos induction in AVP neurons within the PVN relative to controls. To evaluate behavioral responses, AT1a neurons in the MnPO/OVLT were optogenetically stimulated while conscious freely moving mice had access to both water and 0.3M NaCl. Relative to controls, mice delivered ChR2 showed a significant increase in both water and sodium consumption. Collectively, the results suggest that AT1a neurons in the MnPO/OVLT comprise a neuronal circuit that mediates endocrine, cardiovascular and behavioral responses that maintain body fluid homeostasis.

Support or Funding Information

NIH: HL122494 (EGK), MH104641(CJF), HL125805 and AHA GRNT33660969 (AdK)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Selective Breeding and Exercise Affect Midbrain and PAG Volume
Authors: Lee Daisy C. , Ezzat Raymond Z. , Thompson Zoe , Schmill Margaret P. , Garland Theodore
Published: June 2021

Inter‐specific comparative studies have shown that the size of brain structures is often correlated with behavioral propensities or capabilities. Life experiences can contribute to variation in brain‐behavior associations. For example, studies of rodents and humans have shown that environmental enrichment, exercise, and even video games can change the volume of structures within the brain, in as little as 7 days in rodents. More generally, exercise can favorably influence the brain by facilitating different neuroadaptive and neuroprotective processes that cause regions of the brain to change in size. One important region potentially influenced by exercise is the midbrain, which serves key functions in both movement and reward. Within the midbrain, an area of particular interest is the periaqueductal gray (PAG), which functions in suppressing pain and influences anxiety and fear. Another midbrain region, the red nucleus, is involved in limb motor coordination and is the site of origin for dopaminergic neurons. We investigated whether selective breeding for high voluntary exercise and/or wheel access had any significant impact on these regions. We studied 8 lines of mice: 4 selectively‐bred high runner (HR) lines and 4 non‐selected control (C) lines. 50 HR mice and 50 C mice were separated into two groups: wheel access or no wheel access for 10 weeks, beginning at weaning. After the 10 weeks, brains were dissected, sliced at 40 μm, Nissl stained, and photographed. These photographs were traced using ImageJ software to calculate the area, cell quantity, and region volume. Results from analysis of the whole midbrain volume indicate that it was not affected by wheel access but is larger in HR mice, the latter result confirming results of a previous study that used ex vivo magnetic resonance imaging of whole brains. Thus, under these conditions, a genetic history of selective breeding for high voluntary wheel running plays a greater role in affecting midbrain volume than does chronic physical exercise. Linetype and wheel access had an interactive effect on PAG volume: wheel access increased volume in C mice, but decreased it in HR mice, with no main effect of either linetype or wheel access. This result indicates an interesting relationship between selective breeding and exercise that may have implications for the modulation of pain and anxiety. Analysis of the red nucleus is in progress. Previous studies have shown that HR mice respond differently to dopamine‐targeting drugs; therefore, we hypothesize that HR mice may have evolved structural changes in this region.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Activation of μ‐opioid receptors in the rostral ventrolateral medulla blocks the sympathetic counter‐regulatory response to glucoprivation
Authors: Kakall Zohra M. , Farnham Melissa MJ. , Pilowsky Paul M.
Published: June 2021

Intensive insulin therapy is the gold standard for managing serum glucose levels in patients with insulin‐deficient diabetes mellitus. Hypoglycaemia‐associated autonomic failure (HAAF) is a clinical syndrome characterised by the absence of a glucose counter‐regulatory response to hypoglycaemia or glucoprivation. The precise physiologic mechanisms underlying HAAF remain unknown. Recent data from human studies suggests activation of the endogenous opioid system during antecedent hypoglycaemia may contribute to unawareness of hypoglycaemia.

Here, we aimed to determine whether or not activation of rostral ventrolateral medullary (RVLM) μ‐opioid receptors results in downstream sympathoinhibition, resulting in attenuated glucose production, and an impaired counter‐regulatory response following glucoprivation. Experiments were performed in sodium pentobarbital anaesthetised (65 mg/kg) male Sprague‐Dawley rats (250–350g).

Bilateral activation of RVLM μ‐opioid receptors with DAMGO (8 mM, 50 nl) caused depression of adrenal sympathetic nerve activity (ASNA), that lasted at least 60 minutes (Δ−56.9 ± 9.8% vs saline: Δ1.7 ± 4.4%, P<0.05). In parallel, blood glucose levels were also reduced (Δ−0.8 ± 0.2 mM vs saline: Δ0.2 ± 0.3 mM, P<0.05). The counter‐regulatory response to glucoprivation (measured by ASNA efferent activity) induced by 2‐deoxyglucose was completely attenuated 60 minutes following DAMGO microinjections (Δ−4.4 ± 0.7% vs saline+2‐DG: Δ59.6 ± 8.0%, P<0.05). Bilateral μ‐opioid receptor activation also caused a significant decrease in mean arterial pressure (Δ−28.7 ± 6.1 mmHg vs saline: Δ−9.9 ± 7.3 mmHg, P<0.05) and heart rate (Δ−40.4 ± 14.9 bpm vs saline: Δ−11.1 ± 9.7 bpm, P<0.05).

In conclusion, activation of RVLM μ‐opioid receptors reproduces features of HAAF (attenuated neural efferent response to glucoprivation). The mechanism underlying HAAF may include activation of RVLM μ‐opioid receptors to facilitate sympathoinhibition. Coupled with this sympathoinhibition, the reduced blood glucose levels may contribute to HAAF by increasing the threshold to elicit counter‐regulatory response.

Support or Funding Information

National Health and Medical Research Council of Australia, The University of Sydney, The Heart Research Institute

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Evolutionarily‐Conserved Mechanisms of Nutrient Acquisition in the Primordial Vertebrate, the Pacific Hagfish
Authors: Weinrauch Alyssa , Glover Chris , Blewett Tamzin , Clifford Alexander , Goss Greg
Published: June 2021

Hagfish occupy the basal position of vertebrate phylogeny and are thus of interest for studies examining the evolution of vertebrate traits. Despite a morphologically basic digestive tract, the carnivorous hagfish can rapidly and effectively acquire nutrients from which they can persist off of for upwards of 11 months. Previous studies indicate that hagfish preferentially utilize carbohydrates and transition into fat‐fuelled energy sources as fasting progresses, yet few studies examine the mechanisms by which hagfish acquire nutrients. The aim of the present study was to examine and characterize the mechanisms of nutrient acquisition in the hindgut of the Pacific hagfish (Eptatretus stoutii), focusing on one molecule from each category of macronutrients: carbohydrates (glucose), fats (oleic acid) and proteins (alanyl‐alanine). Radiotracer fluxes across intestinal tissue demonstrated concentration‐dependent uptake indicative of regulated transport, for glucose (Km 0.37 mM, Jmax 8.48 nmol/cm2/h), oleic acid (Km 55 μM, Jmax 1131 pmol/cm2/h) and alanyl‐alanine (Km 1071 μM, Jmax 70 nmol/cm2/h). Pharmacological inhibition of glucose transporters (34% decrease with 200 μM cytochalasin‐b) and sodium‐glucose linked transporters (52–83% decrease with 0.0001–1μM phlorizin) suggest mechanisms akin to those in mammals exist in the hagfish hindgut. Further similarity in transport arises in that dipeptide transport is dependent upon sodium‐proton exchange, wherein a reduced sodium environment yields a 48% decrease in transport rates. While specific isoforms of mammalian fatty acid transporters demonstrate insulin sensitivity, hagfish oleic acid transport rates were unaffected by insulin application (average rate 2741± 262 pmol/cm2/h, N=10), despite a noted 71% decrease in plasma glucose concentration. Finally, feeding resulted in significant remodeling of the intestinal mucosa with hindgut absorptive microvilli lengthening by 125% post‐feeding. Correspondingly, an increased rate of transport was noted post‐feeding, with the degree of change dependent upon the substrate type. This study reveals evolutionarily‐conserved mechanisms of nutrient transport over a broad range of substrates in the oldest extant vertebrate and solidifies the applicability of hagfish as a model for studies of early vertebrate evolution.

Support or Funding Information

Supported by NSERC Discovery Grants to GG (203736) and CG (251083)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mimicking Human Cmah Inactivation in Mice Increases Running Endurance and Muscle Respiratory Capacity: Implications for the Evolution of genus Homo
Authors: Okerblom Jonathan , Fletes William , Patel Hemal , Schenk Simon , Varki Ajit , Breen Ellen
Published: June 2021

Compared to other primates, humans are exceptional long‐distance runners, a characteristic that emerged in genus Homo ~2 million years ago (mya), and is generally attributed to anatomical and physiological adaptations such as striding bipedalism and improved heat dissipation. Deletion of a critical exon in the CMAH gene also became fixed 2–3 mya in our ancestral lineage––eliminating CMAH enzymatic activity, which generates the major cell surface sialic acid Neu5Gc, by adding one oxygen atom to the Neu5Ac precursor. Modeling Cmah loss in mice suggested a fertility‐dependent role in emergence of genus Homo and its absence exacerbates human‐like muscular dystrophy phenotypes. Considering these seemingly disparate clues, we posited a role for CMAH loss in the evolution of the hominin endurance phenotype, and evaluated exercise capacity and skeletal muscle oxygen metabolism of Cmah−/− mice. Untrained Cmah−/− mice demonstrated an increased endurance during treadmill running and ran further and faster during 15 days of voluntary running, compared to WT littermates. Time to fatigue during repeated in situ contractions of hind limb muscles was >2‐fold higher in Cmah−/− mice, and a higher capillary‐to‐myofiber ratio was noted. Maximal ex vivo oxidative phosphorylation in muscle fibers was also higher in Cmah−/− mice, and relevant differences in metabolic pathways were noted. Taken together, these data suggest that CMAH loss likely triggered multiple adaptations in the genus Homo that improved skeletal muscle capacity for oxygen delivery and/or utilization––leading to enhanced aerobic capacity, and perhaps providing a selective advantage during the transition towards persistence hunting and other features of Homo.

Support or Funding Information

This work was supported by National Institutes of Health Grants R01GM32373 and R01AR060949

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Comprehensive Lipidome and Proteome Analyses to Identify the Inflammatory and Cardiometabolic Fingerprints of Metabolically “Healthy” Versus “Unhealthy” Obese Subjects
Authors: Rajan Meenu Rohini , Sotak Matus , Barrenäs Fredrik , Tong Shen , Borkowski Kamil , Clark Madison , Fiehn Oliver , Newman John , Wallenius Ville , Lange Stephan , Börgeson Emma
Published: June 2021

Study Objective

Obesity‐related co‐morbidities pose a serious health care system burden. However, 30% of obese subjects do not present with cardiometabolic complications. Here we perform comprehensive lipidome and proteome analyses to identify inflammatory and cardiometabolic fingerprints that characterize metabolically healthy obese (MHO) and metabolically unhealthy obese (MUO) phenotypes.

Methods

Obese patients (BMI 35–50) donated plasma before undergoing bariatric surgery (clinicaltrial.gov NCT02322073). Patients were classified as MHO (n=5) versus MUO (n=9) according to International Diabetes Federation criteria. Metabolically healthy lean (MHL, n=14) subjects were age‐ and sex‐matched to the obese cohort. Plasma samples were analyzed for 480 protein biomarkers related to inflammation and cardiometabolic processes in a multiplexed array. Samples were also subjected to untargeted lipidomics and targeted oxylipin lipidomics analyses.

Results

Gene‐ontology term analysis of the 15 proteins that were significantly decreased/elevated in MHO vs. MUO patients revealed differences in inflammation, metabolism, apoptosis and fibrosis signaling pathways. Furthermore, lipidomics show distinct differences in the lipid profile of MHO and MUO groups. The MUO group displayed increased levels of ceramides, which are implicated in development of insulin resistance and cardiovascular diseases. In contrast, the MHO group exhibited increased levels of anandamide and dihomo‐gamma‐linolenoyl ethanolamide, which are lipids associated with anti‐inflammatory effects. The MUO group also exhibited elevated levels of the cardiometabolic risk factor plasminogen activator inhibitor 1 (PAI‐1). Interestingly, MHO patients presented with increased levels of myeloblastin, which is a serine protease that degrades the PAI‐1–stabilizing protein vitronectin.

Conclusion

In conclusion, we have performed a comprehensive lipidomic and proteomic fingerprinting of MHO and MUO subjects. Our analyses reveal clear stratification of the groups and identify lipid mediators that may be of possible therapeutic use as novel interventions for obesity‐associated pathophysiologies. Work is ongoing to explore the molecular mechanism by which the identified proteins and lipid mediators affect cardiometabolic health in obese patients.

Support or Funding Information

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Effect of long‐term administration of heat‐processed onion (Allium cepa L.) extract on body weight, visceral fat accumulation, and plasma lipid profile in C57BL/6 mice fed high‐fat diets
Authors: Kang Hanna , Kim Tae‐Yang , Kang Yu‐Ri , Lee Jung‐Yun , Lee Jong‐Wook , Kwon Young‐In
Published: June 2021

In the previous study, it was found that Amadori rearrangement compounds‐rich heat‐processed onion reduced postprandial blood glucose increase by reducing absorption of glucose through inhibition of sucrase and α‐glucosidase in the small intestinal tract. This reduced absorption of carbohydrate might control body weight gain due to excessive carbohydrates consumption and induce calorie restriction. To investigate and prove the mechanism for the effects of heat‐processed onion extract (ONI_V) on body weight gain, body weight, plasma lipids, body fat mass, and lipid deposition were evaluated and compared to Garcinia cambogia (GC), a known competitive inhibitor of adenosine 5′‐triphosphate (ATP) citrate lyase in C57BL/6 mice model. Male C57BL/6 mice were fed high‐fat diet (60% kcal fat) with 2% ONI_V or GC used as a positive control. Supplementation of ONI_V effectively lowered the body weight gain, visceral fat accumulation, and plasma lipid concentrations. Compared to control, ONI_V increased the number of adipocytes with a smaller diameter. Interestingly, GC treatment did not change either adipocyte numbers or sizes although total weight of visceral fat pads was significantly reduced compared to control. These results indicate that ONI_V and GC may use different mechanisms in inhibiting weight gain under the current experimental conditions used in this study. Furthermore, ONI_V may reduce weight gain using a similar mechanism of anti‐diabetic drugs, thiazolidinediones (TZDs). TZDs in humans and animals have been shown to be a strong ligand for PPARγ, a nuclear transcription factor that enhances adipocyte differentiation, thereby increasing the number of adipocytes with smaller diameters, which is consistent with the effects of ONI_V observed in this study. According to the obtained results, ONI‐V may be effective not only in reducing weight gains, but also in ameliorating some of the metabolic abnormalities including hyperglycemia, oxidative stress, and inflammation associated with weight gain and obesity.

Support or Funding Information

This research was financially supported by the Ministry of Trade, Industry, and Energy (MOTIE), Korea, under the “Regional Specialized Industry Development Program” supervised by the Korea Institute for Advancement of Technology (KIAT).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Functional Impairment in the Corpus Cavernosum Related to a High Fat Diet is Prevented in Toll‐Like Receptor 9 Mutant Mice
Authors: Priviero Fernanda , Calmasini Fabiano Beraldi , McCarthy Cameron , Wenceslau Camilla Ferreira , Antunes Edson , Webb R. Clinton
Published: June 2021

High fat diets lead to obesity and trigger inflammatory processes which are associated with an increase in the toll‐like receptor 9 (TLR9) signaling pathway in rodent models of non‐alcoholic fatty liver disease. Furthermore, TLR9 signaling plays a role in inflammation regulation of adipose tissue in obesity and metabolic syndrome. Erectile dysfunction (ED) has been correlated with increased inflammatory mediators. Since obesity induces ED, we hypothesize that the impaired function in the corpus cavernosum may be related to an increase in the TLR9 signaling in obese mice. The aim of this study was to evaluate the relaxation and contractile responses of the corpus cavernosum of wild type and TLR9 mutant mice made obese by a high fat diet. Four week old male C57BL/6 and TLR9 mutant mice were fed a high fat diet for 12 weeks. The corpus cavernosum was then mounted on strip myograph for functional evaluation. The contractile and relaxation responses of the corpus cavernosum were evaluated by electrical field stimulation (EFS) and concentration response curves to acetylcholine and phenylephrine. We observed that the relaxation induced by EFS was decreased in wild type obese mice. Deletion of TLR9 prevented this decrease. On the other hand, EFS‐induced contraction at 8 Hz was higher in the corpus cavernosum of obese wild type mice. However, this increase was prevented in TLR9 mutant mice. Furthermore, we observed that the contraction induced by KCl solution (120 mM) and maximal contraction induced by phenylephrine tended to be increased in wild type obese mice only. No changes were observed in the relaxation induced by acetylcholine or in the potency of phenylephrine. In conclusion, these data suggest that TLR9 signaling pathway contributes to erectile dysfunction induced by a high fat diet.

Support or Funding Information

NIH: NHLBI001961FAPESP: 2016/20592‐8

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Estrogen Regulates Daily Metabolic Rhythms in Female Mice
Authors: Pendergast Julie S. , McGann Eric G. , Omotola Oluwabukola B.
Published: June 2021

One‐third of women are obese. Moreover, after menopause, women are increasingly susceptible to obesity comorbidities such as metabolic syndrome and cardiovascular disease, suggesting that estrogen regulates these processes. Shift work, which disrupts circadian rhythms, also increases the risk of obesity and cardiovascular disease in women. In this study, we sought to examine the role of estrogen in regulating daily rhythms associated with the development of obesity. The circadian system controls daily, 24‐h rhythms of behavior and physiology such as the sleep‐wake cycle and the eating rhythm. Our lab previously found that high‐fat diet feeding in male mice, which caused diet‐induced obesity, also disrupted daily rhythms of eating behavior. Male mice typically had robust eating rhythms (eating consolidated during the night) on low‐fat diet (LFD). However, when placed on high‐fat diet (HFD), male mice ate arrhythmically throughout the day. Since previous studies demonstrated that female mice were resistant to diet‐induced obesity, we aimed to determine whether daily metabolic rhythms were also protected from the effects of high‐fat feeding in females. Female C57BL/6J mice (6 weeks old) were ovariectomized and implanted subcutaneously with either a physiological dose of 17β‐estradiol or vehicle (sesame oil) in silastic tubing. At 7 weeks old, females were single‐housed in cages in light‐tight boxes in 12L:12D and fed LFD (10% kcal fat) for 1 week and then HFD (45% kcal fat) for 1 week. Locomotor activity and eating behavior rhythms were continuously measured with infrared sensors and video cameras, respectively. Body weight, food intake, body composition and fasting blood glucose were also measured. Consistent with previous studies, we found that estrogen replacement in ovariectomized mice inhibited HFD‐induced weight gain and adiposity in females. In contrast to males, whose daily rhythm of eating behavior was abrogated during high‐fat feeding, intact females had robust eating behavior rhythms on high‐fat diet. However, after ovariectomy, females had low‐amplitude or arrhythmic eating behavior during high‐fat feeding. The robust daily rhythm of eating behavior was rescued in ovariectomized females with estrogen replacement. Our data show that estrogen confers robust, high‐amplitude eating behavior rhythms during high‐fat feeding in female mice. Notably, these females are also protected from diet‐induced obesity. Together, our data show that regulation of daily metabolic rhythms is markedly different in males and females.

Support or Funding Information

This study was funded by National Institutes of Health grants R03DK098321, P20GM103527, K01DK098321, and P30DK058404, and the University of Kentucky.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Sexually Dimorphic Ano2 Expression in Nodose Neurons Determines CCK‐mediated Satiation and Obesity in Heterozygote Male Mice
Authors: Lu Yongjun , Wang Runping , Cicha Michael Z. , Chapleau Mark W. , Abboud Francois M.
Published: June 2021

The gut peptide cholecystokinin (CCK) contributes to neurally mediated post prandial satiety. Our previous results indicate that high fat diet downregulates the CCK‐sensitive anoctamins (Ano1 and Ano2) that function as calcium‐activated chloride channels (CaCCs) in intestinal vagal afferents. Using Cre‐loxP system, we generated heterozygote (HET) Nav1.8CreAno2fl/WT mice. The endogenous Scn10a promoter drives Cre expression (Nav1.8Cre) selectively in sensory neurons of the nodose, dorsal root and trigeminal ganglia where loxP sites flanked Ano2 exon 12. The male HET mice exhibited an obese phenotype and decreased sensitivity to CCK. To assess the Ano2 expression in HET vs. control (Nav1.8Cre+/−) mice, we first did qRT‐PCR on whole nodose ganglia obtained under anesthesia at 50 weeks of age and found no significant difference in Ano2 mRNA expression (n=4, p>0.05). Ano2 gene may be expressed in non‐neuronal cells of nodose ganglia while Cre expression is selective to neurons. We measured Ano2 mRNAs in nodose neurons cultured for 16–18 hours using single cell qRT‐PCR. Cre positive neurons were 57% (12 of 21) in HET and 74% (29 of 39) in control, indicating a lower efficiency of Cre expression in HET. Correspondingly, Ano2 positive neurons were 48% (10 of 21) and 62% (24 of 39), respectively, indicating the Ano2 allelic deletion in HET. The combined Cre and Ano2 positivity in HET was 29% (6 of 21) vs. 54% (21 of 39) in control. Most importantly the Ano2 mRNA levels in HET neurons (n=10) were 20% of the levels measured in control neurons (n=24, p<0.05) (0.20±0.16 vs. 1.00±0.57). The Ano2 expression in individual nodose neurons of female mice did not show a reduction or even higher in HET (n=27) vs. control (n=28) (2.58±1.48 vs. 1.42±1.27, p>0.05). The female HET mice remained CCK sensitive indicating a sexual dimorphism. We conclude that differences in expression of Ano2 mRNA support our findings of CCK insensitivity and selective obesity in male but not female HET mice (HL14388).

Support or Funding Information

NIH HL14388

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
DELETION OF MICRORNA‐22 ENHANCES THERMOGENIC GENE EXPRESSION IN WHITE ADIPOSE TISSUE OF OBESE MICE
Authors: Lima Vanessa Morais , Fonseca Renata Inzinna , Wang Da‐Zhi , Diniz Gabriela Placona
Published: June 2021

Background

Obesity is a major risk factor for several cardiovascular and metabolic disorders. In the last years, diverse studies have suggested that browning of white adipose tissue (WAT) may be used as a novel strategy for treatment of diseases associated to obesity. We recently reported that loss of microRNA‐22 attenuated the fat mass gain induced by high fat (HF) diet. In addition, loss of microRNA‐22 enhanced energy expenditure in mice fed a HF diet, suggesting that microRNA‐22 may play a critical role in the control of metabolic disorders observed in obesity. However, the possible mechanisms by which microRNA‐22 mediates the gain of WAT in response to HF feeding are unclear. In the present study, we investigated the contribution of microRNA‐22 in browning of WAT.

Methods

Male microRNA‐22 knockout (miR22KO) and wild type (WT) mice were fed a chow diet or HF diet for 12 weeks. Body weight gain was monitored weekly. Epididymal fat was collected and expression of genes involved in browning of WAT was evaluated by qPCR.

Results

miR22KO and WT mice fed HF diet displayed increased body weight gain when compared to their respective controls fed a chow diet. Loss of microRNA‐22 did not attenuate the body weight gain mediated by HF diet. Both miR22KO and WT mice fed HF diet exhibited increased epididymal fat mass compared to their respective controls. However, deletion of microRNA‐22 attenuated the gain of fat mass induced by HF diet. Analysis of gene expression demonstrated that miR22KO mice fed either a chow or HF diet displayed higher expression levels of UCP1 in WAT. In addition, miR22KO mice fed HF diet exhibited increased expression levels of Cidea and Prdm16 in WAT when compared to WT mice fed HF diet.

Conclusions

These findings suggest that loss of microRNA‐22 induces thermogenic gene expression in WAT of obese mice.

Support or Funding Information

Funding: Sao Paulo Research Foundation (FAPESP #2015/21859‐5; #2017/01558‐6).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Melatonin or Dark Therapy Reduce Biliary Damage, Inflammation and Liver Fibrosis in a Murine Model of Early Stage Primary Biliary Cholangitis
Authors: Kennedy Lindsey , Wu Nan , Francis Heather , Venter Julie , Meng Fanyin , Kyritsi Konstantina , Zhou Tianhao , Gaudio Eugenio , Glaser Shannon , Alpini Gianfranco
Published: June 2021

Background

Primary biliary cholangitis (PBC) is characterized by increased biliary damage, inflammation and liver fibrosis. Early stage PBC is marked by biliary proliferation, whereas late stage PBC shows ductopenia. We have shown that dominant‐negative transforming growth factor b receptor II (dnTGFβRII) mice at 12 wk of age mimic early stage PBC. We have found that melatonin therapy or prolonged exposure to complete darkness reduces biliary hyperplasia and liver fibrosis in models of cholestasis. However, the impact of melatonin or dark therapy on PBC‐related injury is unknown. The aim of our study was to evaluate the effects of melatonin or dark therapy in a mouse model of early stage PBC.

Methods

We used background‐matched, male wild‐type (WT) and dnTGFβRII at 12 wk of age that were given drinking water containing melatonin (0.03%) or placed in complete darkness for 1 wk along with the related controls. Liver damage was evaluated by H&E. Intrahepatic bile duct mass (IBDM) was measured by CK‐19 staining. Biliary senescence was evaluated by staining for p16 and p21, and SA‐β‐galactosidase activity. Biliary and liver inflammation were determined by IL‐6 and F4/80 (Kupffer cell marker) staining. Liver fibrosis was determined by Sirius Red staining and immunofluorescence for collagen type‐1a. Hepatic stellate cell (HSC) activation was shown by SYP‐9 and α‐SMA staining. Human control and early stage PBC serum samples were obtained, and serum melatonin levels were measured by EIA.

Results

dnTGFβRII at 12 wk of age (early stage PBC mouse model) treated with melatonin or complete darkness had decreased (i) IBDM, (ii) biliary senescence, (iii) liver fibrosis, (iv) biliary and liver inflammation, and (v) HSC activation/liver fibrosis. Human early stage PBC samples had decreased serum melatonin levels.

Conclusion

Inhibition of melatonin signaling perpetuates biliary damage associated with PBC. Restoration of melatonin‐dependent signaling via melatonin treatment or dark therapy may be therapeutic for patients with early stage PBC.

Support or Funding Information

NIH NIDDK R01, VA Merit

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Calreticulin stabilizes vascular endothelial growth factor‐A mRNA via interaction with AU‐rich element at 3′‐UTR
Authors: Chen Chih‐Yu , Chien Yin‐Chieh , Lee Hsinyu
Published: June 2021

Messenger RNA (mRNA) stability is a post‐transcriptional regulation that determines mRNA fate and influences multiple cellular functions. Previous studies have demonstrated that AU‐rich element (ARE) in 3′‐untranslated region (UTR) of mRNA is critical for mRNA stability via interaction with ARE‐binding proteins (ARE‐BPs). Chaperone protein calreticulin (CRT) has been reported to bind the 3′‐UTR, suggesting that it may act as a novel ARE‐BP. The expression level of CRT positively is correlated with the expression of angiogenic factor vascular endothelial growth factor‐A (VEGF‐A). However, the detail regulatory mechanism of CRT on VEGF‐A expression remains elusive. Therefore, we aimed to investigate whether CRT regulates mRNA stability of VEGF‐A through interaction with ARE. Our results showed that depletion of CRT significantly destabilized VEGF‐A mRNA and subsequently decreased the expression levels of both VEGF‐A RNA and protein in PC3 human prostate cancer cell line. Since several AREs were identified in the mRNA of VEGF‐A, we further explore the relationship between CRT and these AREs. Pull‐down analysis demonstrated that CRT directly interacts with the ARE region of VEGF‐A mRNA. In addition, we constructed luciferase vectors contained the ARE of VEGF‐A and co‐transfected with siRNA of CRT or CRT overexpression vector. Our results demonstrated that CRT interacts with ARE in 3′‐UTR of VEGF‐A mRNA. In summary, this study suggests that CRT stabilizes VEGF‐A mRNA through interacting with ARE at the 3′‐UTR of VEGF‐A mRNA.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.