Siqi Jing, Chi Geng, Penglai Liu, Dejuan Wang, Qun Li, Anan Li
{"title":"Serotonergic input from the dorsal raphe nucleus shapes learning-associated odor responses in the olfactory bulb","authors":"Siqi Jing, Chi Geng, Penglai Liu, Dejuan Wang, Qun Li, Anan Li","doi":"10.1111/apha.14198","DOIUrl":"10.1111/apha.14198","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Aim</h3>\u0000 \u0000 <p>Neural activity in the olfactory bulb (OB) can represent odor information during different brain and behavioral states. For example, the odor responses of mitral/tufted (M/T) cells in the OB change during learning of odor-discrimination tasks and, at the network level, beta power increases and the high gamma (HG) power decreases during odor presentation in such tasks. However, the neural mechanisms underlying these observations remain poorly understood. Here, we investigate whether serotonergic modulation from the dorsal raphe nucleus (DRN) to the OB is involved in shaping activity during the learning process in a go/no-go task in mice.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Fiber photometry was used to record the population activity of DRN serotonergic neurons during a go/no-go task. In vivo electrophysiology was used to record neural activity (single units and local field potentials) in the OB during the go/no-go task. Real-time place preference (RTPP) and intracranial light administration in a specific subarea (iClass) tests were used to assess the ability of mice to encoding reward information.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Odor-evoked population activity in serotonergic neurons in the DRN was shaped during the learning process in a go/no-go task. In the OB, neural activity from oscillations to single cells showed complex, learning-associated changes and ability to encode information during an odor discrimination task. However, these properties were not observed after ablation of DRN serotonergic neurons.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The activity of neural networks and single cells in the OB, and their ability to encode information about odor value, are shaped by serotonergic projections from the DRN.</p>\u0000 </section>\u0000 </div>","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"240 9","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141490085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hannah G. Caldwell, Ryan L. Hoiland, Anthony R. Bain, Connor A. Howe, Jay M. J. R. Carr, Travis D. Gibbons, Cody G. Durrer, Michael M. Tymko, Benjamin S. Stacey, Damian M. Bailey, Mypinder S. Sekhon, David B. MacLeod, Philip N. Ainslie
{"title":"Evidence for direct CO2-mediated alterations in cerebral oxidative metabolism in humans","authors":"Hannah G. Caldwell, Ryan L. Hoiland, Anthony R. Bain, Connor A. Howe, Jay M. J. R. Carr, Travis D. Gibbons, Cody G. Durrer, Michael M. Tymko, Benjamin S. Stacey, Damian M. Bailey, Mypinder S. Sekhon, David B. MacLeod, Philip N. Ainslie","doi":"10.1111/apha.14197","DOIUrl":"10.1111/apha.14197","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Aim</h3>\u0000 \u0000 <p>How the cerebral metabolic rates of oxygen and glucose utilization (CMRO<sub>2</sub> and CMR<sub>Glc</sub>, respectively) are affected by alterations in arterial PCO<sub>2</sub> (PaCO<sub>2</sub>) is equivocal and therefore was the primary question of this study.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>This retrospective analysis involved pooled data from four separate studies, involving 41 healthy adults (35 males/6 females). Participants completed stepwise steady-state alterations in PaCO<sub>2</sub> ranging between 30 and 60 mmHg. The CMRO<sub>2</sub> and CMR<sub>Glc</sub> were assessed via the Fick approach (CBF × arterial-internal jugular venous difference of oxygen or glucose content, respectively) utilizing duplex ultrasound of the internal carotid artery and vertebral artery to calculate cerebral blood flow (CBF).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The CMRO<sub>2</sub> was altered by 0.5 mL × min<sup>−1</sup> (95% CI: −0.6 to −0.3) per mmHg change in PaCO<sub>2</sub> (<i>p</i> < 0.001) which corresponded to a 9.8% (95% CI: −13.2 to −6.5) change in CMRO<sub>2</sub> with a 9 mmHg change in PaCO<sub>2</sub> (inclusive of hypo- and hypercapnia). The CMR<sub>Glc</sub> was reduced by 7.7% (95% CI: −15.4 to −0.08, <i>p</i> = 0.045; i.e., reduction in net glucose uptake) and the oxidative glucose index (ratio of oxygen to glucose uptake) was reduced by 5.6% (95% CI: −11.2 to 0.06, <i>p</i> = 0.049) with a + 9 mmHg increase in PaCO<sub>2</sub>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Collectively, the CMRO<sub>2</sub> is altered by approximately 1% per mmHg change in PaCO<sub>2</sub>. Further, glucose is incompletely oxidized during hypercapnia, indicating reductions in CMRO<sub>2</sub> are either met by compensatory increases in nonoxidative glucose metabolism or explained by a reduction in total energy production.</p>\u0000 </section>\u0000 </div>","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"240 9","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/apha.14197","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141490083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shane K. Maloney, Michael R. Kearney, Duncan Mitchell
{"title":"Indices of human heat stress in times of climate change","authors":"Shane K. Maloney, Michael R. Kearney, Duncan Mitchell","doi":"10.1111/apha.14196","DOIUrl":"10.1111/apha.14196","url":null,"abstract":"<p>Body temperature is one of the cardinal regulated variables in human physiology, along with blood gasses, pH, and osmolality. Pathological deviations of body temperature from normal, some potentially lethal, are becoming more likely with climate change. Sherwood and Huber<span><sup>1</sup></span> famously used a critical wet-bulb temperature that would cause pathology to project areas of the world that would become uninhabitable in a climate-changed future. Many other indices that incorporate the wet-bulb temperature have been advanced to predict human heat stress. As pointed out by Maloney,<span><sup>2</sup></span> and recently confirmed empirically,<span><sup>3</sup></span> those indices underestimate the impact of climate change on human thermoregulation, especially at lower humidity when physiological, rather than environmental, factors limit evaporative cooling (Figure 1).</p><p>Because the human body exchanges heat with the environment by four routes (conduction, convection, radiation, and evaporation), each impacted by different environmental variables, no single number can quantify that heat exchange accurately.<span><sup>5</sup></span> But single numbers have nevertheless been proposed as indices of human heat stress. Because the dry-bulb temperature was poor at predicting the thermoregulatory responses of humans to different environments, in 1905 the English physiologist John Scott Haldane proposed the wet-bulb temperature as an alternative. The wet-bulb temperature is measured by placing a wetted sleeve over the bulb of a normal thermometer. Evaporation from the sleeve lowers the reading on the thermometer; the lower the humidity, the lower the reading of the wet-bulb thermometer below that of the normal thermometer. Wet-bulb temperature has been incorporated in many of the more than 150 indices of human thermal stress that have been developed over the past century.<span><sup>5</sup></span> As well as underestimating the likelihood of pathology in some conditions, many of those indices also ignore the impact of air movement on both human heat exchange and on the wet-bulb temperature.</p><p>We all have been comforted by a breeze on a hot day, if we have been sweating. That effect has been quantified for acclimated women walking on a treadmill by measuring the upper limits of the prescriptive zone (ULPZ; that range of conditions in which core body temperature is affected by the level of metabolic heat production but not by the environment). In still air, the women could achieve heat balance in the conditions indicated by red shading below the dotted line in Figure 1. Conditions above that dotted line were above ULPZ, and the women became hyperthermic. At 1 ms<sup>−1</sup> of forced air movement, their ULPZ increased to include the conditions indicated by dark-yellow shading below the solid line in Figure 1, so the ability of those women to avoid pathology improved. That improvement would not have been predicted by an index based on we","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"240 9","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/apha.14196","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141490084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Multigenerational exposure to temperature influences mitochondrial oxygen fluxes in the Medaka fish (Oryzias latipes)","authors":"Julie Morla, Karine Salin, Rémy Lassus, Julie Favre-Marinet, Arnaud Sentis, Martin Daufresne","doi":"10.1111/apha.14194","DOIUrl":"10.1111/apha.14194","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Aim</h3>\u0000 \u0000 <p>Thermal sensitivity of cellular metabolism is crucial for animal physiology and survival under climate change. Despite recent efforts, effects of multigenerational exposure to temperature on the metabolic functioning remain poorly understood. We aimed at determining whether multigenerational exposure to temperature modulate the mitochondrial respiratory response of Medaka fish.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We conducted a multigenerational exposure with Medaka fish reared multiple generations at 20 and 30°C (COLD and WARM fish, respectively). We then measured the oxygen consumption of tail muscle at two assay temperatures (20 and 30°C). Mitochondrial function was determined as the respiration supporting ATP synthesis (OXPHOS) and the respiration required to offset proton leak (LEAK(Omy)) in a full factorial design (COLD-20°C; COLD-30°C; WARM-20°C; WARM-30°C).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>We found that higher OXPHOS and LEAK fluxes at 30°C compared to 20°C assay temperature. At each assay temperature, WARM fish had lower tissue oxygen fluxes than COLD fish. Interestingly, we did not find significant differences in respiratory flux when mitochondria were assessed at the rearing temperature of the fish (i.e., COLD-20°C vs. WARM −30°C).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The lower OXPHOS and LEAK capacities in warm fish are likely the result of the multigenerational exposure to warm temperature. This is consistent with a modulatory response of mitochondrial capacity to compensate for potential detrimental effects of warming on metabolism. Finally, the absence of significant differences in respiratory fluxes between COLD-20°C and WARM-30°C fish likely reflects an optimal respiration flux when organisms adapt to their thermal conditions.</p>\u0000 </section>\u0000 </div>","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"240 8","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141453792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optimizing diuretic treatment of patients with edema and nephrotic syndrome","authors":"Gitte R. Hinrichs, Boye L. Jensen","doi":"10.1111/apha.14195","DOIUrl":"10.1111/apha.14195","url":null,"abstract":"<p>In the current issue of <i>Acta Physiologica</i>,<span><sup>1</sup></span> Schork <i>et al.</i> address a significant unresolved issue that puzzles researchers and challenges clinical decision-making, namely how to treat best edema associated with nephrotic syndrome (NS). NS is a kidney disorder with primary or secondary injury to the glomerular filtration barrier. NS is characterized by protein loss in urine above 3.5 g/d and generalized edema. Treatment of NS edema constitutes a therapeutic challenge. There is an unmet clinical need to evaluate the efficacy of diuretics and a need for better understanding of the pathogenesis as stated in Kidney Disease/Improving Global Outcome (KDIGO) 2021 guidelines on glomerular disease.<span><sup>2</sup></span> By a gold-standard randomized approach, Schork <i>et al.</i> compared the efficacy of the epithelial sodium channel (ENaC) blocker amiloride with the loop diuretic furosemide in adult patients with edema and NS. The primary endpoint was “overhydration” (OH) determined by non-invasive bioimpedance. Amiloride monotherapy was comparable to furosemide with similar reduction achieved in OH after 8 days. By testing these diuretic treatments, the authors provide further insight into the pathophysiological mechanism of salt retention known to reside in the tubular system.<span><sup>1</sup></span></p><p>The rationale for investigating amiloride, a theoretically weak diuretic compared to the more potent loop diuretic-class of drugs, is based on human studies demonstrating limited efficacy of volume correction with albumin infusion, renin-angiotensin system blockers and with furosemide. Preclinical studies in mice and rats with induced NS show that ENaC inhibitors mitigate sodium retention<span><sup>3</sup></span> although hormonal stimulators of ENaC, aldosterone, and angiotensin II, are unchanged or suppressed in plasma. The concept that ENaC may be activated by alternative pathways including proteolytic cleavage through soluble, extracellular, proteases present in tubular fluid in proteinuria has gained support. Not least the group of Schork <i>et al.</i> has contributed significantly to this concept and published in <i>Acta Physiologica</i> that the protease inhibitor aprotinin leads to natriuresis in mice with NS.<span><sup>4</sup></span></p><p>Intervention studies in patients with NS edema are limited. In pediatric patients, amiloride was as effective as furosemide and additive.<span><sup>5</sup></span> In adult patients with NS, amiloride (or its analogue triamterene) has been administered as a rational add-on for sequential blockade of Na<sup>+</sup> transporters along the nephron<span><sup>6, 7</sup></span> or as add-on in single patients with NS and resistant edema with remarkable, but casuistic, effect.<span><sup>8</sup></span></p><p>Schork <i>et al.</i> show in adult patients with NS<span><sup>1</sup></span> that amiloride significantly reduced OH on Day 8, and both drugs did at Day 16 compared to","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"240 8","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/apha.14195","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141453793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Evany Dinakis, Joanne A. O'Donnell, Francine Z. Marques
{"title":"The gut–immune axis during hypertension and cardiovascular diseases","authors":"Evany Dinakis, Joanne A. O'Donnell, Francine Z. Marques","doi":"10.1111/apha.14193","DOIUrl":"10.1111/apha.14193","url":null,"abstract":"<p>The gut-immune axis is a relatively novel phenomenon that provides mechanistic links between the gut microbiome and the immune system. A growing body of evidence supports it is key in how the gut microbiome contributes to several diseases, including hypertension and cardiovascular diseases (CVDs). Evidence over the past decade supports a causal link of the gut microbiome in hypertension and its complications, including myocardial infarction, atherosclerosis, heart failure, and stroke. Perturbations in gut homeostasis such as dysbiosis (i.e., alterations in gut microbial composition) may trigger immune responses that lead to chronic low-grade inflammation and, ultimately, the development and progression of these conditions. This is unsurprising, as the gut harbors one of the largest numbers of immune cells in the body, yet is a phenomenon not entirely understood in the context of cardiometabolic disorders. In this review, we discuss the role of the gut microbiome, the immune system, and inflammation in the context of hypertension and CVD, and consolidate current evidence of this complex interplay, whilst highlighting gaps in the literature. We focus on diet as one of the major modulators of the gut microbiota, and explain key microbial-derived metabolites (e.g., short-chain fatty acids, trimethylamine <i>N</i>-oxide) as potential mediators of the communication between the gut and peripheral organs such as the heart, arteries, kidneys, and the brain via the immune system. Finally, we explore the dual role of both the gut microbiome and the immune system, and how they work together to not only contribute, but also mitigate hypertension and CVD.</p>","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"240 8","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/apha.14193","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141425725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Emanuele R. G. Plini, Michael C. Melnychuk, Ralph Andrews, Rory Boyle, Robert Whelan, Jeffrey S. Spence, Sandra B. Chapman, Ian H. Robertson, Paul M. Dockree
{"title":"Greater physical fitness (\u0000 \u0000 \u0000 \u0000 VO\u0000 \u0000 2\u0000 max\u0000 \u0000 \u0000 \u0000 ) in healthy older adults associated with increased integrity of the locus coeruleus–noradrenergic system","authors":"Emanuele R. G. Plini, Michael C. Melnychuk, Ralph Andrews, Rory Boyle, Robert Whelan, Jeffrey S. Spence, Sandra B. Chapman, Ian H. Robertson, Paul M. Dockree","doi":"10.1111/apha.14191","DOIUrl":"10.1111/apha.14191","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Aim</h3>\u0000 \u0000 <p>Physical activity (PA) is a key component for brain health and Reserve, and it is among the main dementia protective factors. However, the neurobiological mechanisms underpinning Reserve are not fully understood. In this regard, a noradrenergic (NA) theory of cognitive reserve (Robertson, 2013) has proposed that the upregulation of NA system might be a key factor for building reserve and resilience to neurodegeneration because of the neuroprotective role of NA across the brain. PA elicits an enhanced catecholamine response, in particular for NA. By increasing physical commitment, a greater amount of NA is synthetised in response to higher oxygen demand. More physically trained individuals show greater capabilities to carry oxygen resulting in greater <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>Vo</mi>\u0000 <msub>\u0000 <mn>2</mn>\u0000 <mi>max</mi>\u0000 </msub>\u0000 </msub>\u0000 </mrow>\u0000 </semantics></math> – a measure of oxygen uptake and physical fitness (PF).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We hypothesized that greater <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>Vo</mi>\u0000 <msub>\u0000 <mn>2</mn>\u0000 <mi>max</mi>\u0000 </msub>\u0000 </msub>\u0000 </mrow>\u0000 </semantics></math> would be related to greater Locus Coeruleus (LC) MRI signal intensity. In a sample of 41 healthy subjects, we performed Voxel-Based Morphometry analyses, then repeated for the other neuromodulators as a control procedure (Serotonin, Dopamine and Acetylcholine).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>As hypothesized, greater <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>Vo</mi>\u0000 <msub>\u0000 <mn>2</mn>\u0000 <mi>max</mi>\u0000 </msub>\u0000 </msub>\u0000 </mrow>\u0000 </semantics></math> related to greater LC signal intensity, and weaker associations emerged for the other neuromodulators.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>This newly established link between <span></span><math>\u0000 ","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"240 8","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141416742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}