BMC Physiology最新文献

{"title":"Antenatal maternal low protein diet: ACE-2 in the mouse lung and sexually dimorphic programming of hypertension.","authors":"Ravi Goyal,&nbsp;Jonathan Van-Wickle,&nbsp;Dipali Goyal,&nbsp;Lawrence D Longo","doi":"10.1186/s12899-015-0016-6","DOIUrl":"https://doi.org/10.1186/s12899-015-0016-6","url":null,"abstract":"<p><p>Elevated blood pressure is an important global health problem, and in-utero under-nutrition may be an important factor in the pathogenesis of hypertension. In the present study, we tested the hypothesis that antenatal maternal low protein diet (MLPD) leads to sexually dimorphic developmental programming of the components of the pulmonary renin-angiotensin system. This may be important in the antenatal MLPD-associated development of hypertension. In pregnant mice, we administered normal (control) and isocaloric 50% protein restricted diet, commencing one week before mating and continuing until delivery of the pups. From the 18th to 24th week postnatal, we measured blood pressure in the offspring by use of a non-invasive tail-cuff method. In the same mice, we examined the mRNA and protein expression of the key components of the pulmonary renin-angiotensin system. Also, we examined microRNA complementary to angiotensin converting enzymes (ACE) 2 in the offspring lungs. Our results demonstrate that as a consequence of antenatal MLPD: 1) pup birthweight was significantly reduced in both sexes. 2) female offspring developed hypertension, but males did not. 3) In female offspring, ACE-2 protein expression was significantly reduced without any change in the mRNA levels. 4) miRNA 429, which has a binding site on ACE-2 - 3' UTR was significantly upregulated in the female antenatal MLPD offspring. 5) In males, ACE-2 mRNA and protein expression were unaltered. We conclude that in the mouse, antenatal MLPD-induced reduction of ACE-2 in the female offspring lung may be an important mechanisms in sexually dimorphic programming of hypertension.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"15 ","pages":"2"},"PeriodicalIF":0.0,"publicationDate":"2015-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-015-0016-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33175881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exercise performed around MLSS decreases systolic blood pressure and increases aerobic fitness in hypertensive rats.","authors":"Bernardo A Petriz,&nbsp;Jeeser A Almeida,&nbsp;Clarissa P C Gomes,&nbsp;Carlos Ernesto,&nbsp;Rinaldo W Pereira,&nbsp;Octavio L Franco","doi":"10.1186/s12899-015-0015-7","DOIUrl":"https://doi.org/10.1186/s12899-015-0015-7","url":null,"abstract":"<p><strong>Background: </strong>Exercise is a non-pharmacologic agent widely used for hypertension control, where low intensity is often associated with blood pressure reduction. Maximal lactate steady state (MLSS) was recently identified in spontaneously hypertensive rats (SHRs) as an important step in establishing secure intensities for prescribing exercise for hypertensive phenotypes. Here we verified the effects of training around MLSS, 20% below MLSS, and 15% above MLSS on aerobic fitness and blood pressure status of SHR. Eighteen-week-old SHRs (n = 5, ~ 172.4 ± 8.1 mm Hg systolic blood pressure) were trained on a treadmill for 4 weeks for 30 min/day, 5 days/week at a velocity of 20 m.min(-1). After training, a novel MLSS and incremental test was performed to evaluate the animals' aerobic fitness. Furthermore, ~ 22-week-old SHRs (n = 12, ~169.8 ± 13.8 mm Hg systolic blood pressure) were divided into non-exercised (CG, n = 4), low intensity (LIG, n = 4) and high intensity (HIG, n = 4) groups, where rats were trained at 16 m.min(-1) and 23 m.min(-1) respectively for 30 min/day, 5 days/week for 4 weeks.</p><p><strong>Results: </strong>Exercise performed at MLSS enhanced aerobic fitness, leading to a novel MLSS, identified around 30 m.min(-1). Low and high intensity training reduced systolic blood pressure and only high intensity training led to improved aerobic fitness (28.1%, p < 0.01).</p><p><strong>Conclusions: </strong>Therefore, our data indicate a decrease in blood pressure due to low and high exercise intensity, and an increase in aerobic fitness provided by high-intensity exercise in SHRs.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"15 ","pages":"1"},"PeriodicalIF":0.0,"publicationDate":"2015-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-015-0015-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33229244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alteration in circulating metabolites during and after heat stress in the conscious rat: potential biomarkers of exposure and organ-specific injury.","authors":"Danielle L Ippolito, John A Lewis, Chenggang Yu, Lisa R Leon, Jonathan D Stallings","doi":"10.1186/s12899-014-0014-0","DOIUrl":"10.1186/s12899-014-0014-0","url":null,"abstract":"<p><strong>Background: </strong>Heat illness is a debilitating and potentially life-threatening condition. Limited data are available to identify individuals with heat illness at greatest risk for organ damage. We recently described the transcriptomic and proteomic responses to heat injury and recovery in multiple organs in an in vivo model of conscious rats heated to a maximum core temperature of 41.8°C (Tc,Max). In this study, we examined changes in plasma metabolic networks at Tc,Max, 24, or 48 hours after the heat stress stimulus.</p><p><strong>Results: </strong>Circulating metabolites were identified by gas chromatography/mass spectrometry and liquid chromatography/tandem mass spectrometry. Bioinformatics analysis of the metabolomic data corroborated proteomics and transcriptomics data in the tissue at the pathway level, supporting modulations in metabolic networks including cell death or catabolism (pyrimidine and purine degradation, acetylation, sulfation, redox alterations and glutathione metabolism, and the urea cycle/creatinine metabolism), energetics (stasis in glycolysis and tricarboxylic acid cycle, β-oxidation), cholesterol and nitric oxide metabolism, and bile acids. Hierarchical clustering identified 15 biochemicals that differentiated animals with histopathological evidence of cardiac injury at 48 hours from uninjured animals. The metabolic networks perturbed in the plasma corroborated the tissue proteomics and transcriptomics pathway data, supporting a model of irreversible cell death and decrements in energetics as key indicators of cardiac damage in response to heat stress.</p><p><strong>Conclusions: </strong>Integrating plasma metabolomics with tissue proteomics and transcriptomics supports a diagnostic approach to assessing individual susceptibility to organ injury and predicting recovery after heat stress.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"14 ","pages":"14"},"PeriodicalIF":0.0,"publicationDate":"2014-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-014-0014-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33005166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CaMKII content affects contractile, but not mitochondrial, characteristics in regenerating skeletal muscle.","authors":"Wouter Eilers,&nbsp;Richard T Jaspers,&nbsp;Arnold de Haan,&nbsp;Céline Ferrié,&nbsp;Paola Valdivieso,&nbsp;Martin Flück","doi":"10.1186/s12899-014-0007-z","DOIUrl":"https://doi.org/10.1186/s12899-014-0007-z","url":null,"abstract":"<p><strong>Background: </strong>The multi-meric calcium/calmodulin-dependent protein kinase II (CaMKII) is the main CaMK in skeletal muscle and its expression increases with endurance training. CaMK family members are implicated in contraction-induced regulation of calcium handling, fast myosin type IIA expression and mitochondrial biogenesis. The objective of this study was to investigate the role of an increased CaMKII content for the expression of the contractile and mitochondrial phenotype in vivo. Towards this end we attempted to co-express alpha- and beta-CaMKII isoforms in skeletal muscle and characterised the effect on the contractile and mitochondrial phenotype.</p><p><strong>Results: </strong>Fast-twitch muscle m. gastrocnemius (GM) and slow-twitch muscle m. soleus (SOL) of the right leg of 3-month old rats were transfected via electro-transfer of injected expression plasmids for native α/β CaMKII. Effects were identified from the comparison to control-transfected muscles of the contralateral leg and non-transfected muscles. α/β CaMKII content in muscle fibres was 4-5-fold increased 7 days after transfection. The transfection rate was more pronounced in SOL than GM muscle (i.e. 12.6 vs. 3.5%). The overexpressed α/β CaMKII was functional as shown through increased threonine 287 phosphorylation of β-CaMKII after isometric exercise and down-regulated transcripts COXI, COXIV, SDHB after high-intensity exercise in situ. α/β CaMKII overexpression under normal cage activity accelerated excitation-contraction coupling and relaxation in SOL muscle in association with increased SERCA2, ANXV and fast myosin type IIA/X content but did not affect mitochondrial protein content. These effects were observed on a background of regenerating muscle fibres.</p><p><strong>Conclusion: </strong>Elevated CaMKII content promotes a slow-to-fast type fibre shift in regenerating muscle but is not sufficient to stimulate mitochondrial biogenesis in the absence of an endurance stimulus.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"14 ","pages":"7"},"PeriodicalIF":0.0,"publicationDate":"2014-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-014-0007-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32913883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Big data in wildlife research: remote web-based monitoring of hibernating black bears.","authors":"Timothy G Laske,&nbsp;David L Garshelis,&nbsp;Paul A Iaizzo","doi":"10.1186/s12899-014-0013-1","DOIUrl":"https://doi.org/10.1186/s12899-014-0013-1","url":null,"abstract":"<p><strong>Background: </strong>Numerous innovations for the management and collection of \"big data\" have arisen in the field of medicine, including implantable computers and sensors, wireless data transmission, and web-based repositories for collecting and organizing information. Recently, human clinical devices have been deployed in captive and free-ranging wildlife to aid in the characterization of both normal physiology and the interaction of animals with their environment, including reactions to humans. Although these devices have had a significant impact on the types and quantities of information that can be collected, their utility has been limited by internal memory capacities, the efforts required to extract and analyze information, and by the necessity to handle the animals in order to retrieve stored data.</p><p><strong>Results: </strong>We surgically implanted miniaturized cardiac monitors (1.2 cc, Reveal LINQ™, Medtronic Inc.), a newly developed human clinical system, into hibernating wild American black bears (N = 6). These devices include wireless capabilities, which enabled frequent transmissions of detailed physiological data from bears in their remote den sites to a web-based data storage and management system. Solar and battery powered telemetry stations transmitted detailed physiological data over the cellular network during the winter months. The system provided the transfer of large quantities of data in near-real time. Observations included changes in heart rhythms associated with birthing and caring for cubs, and in all bears, long periods without heart beats (up to 16 seconds) occurred during each respiratory cycle.</p><p><strong>Conclusions: </strong>For the first time, detailed physiological data were successfully transferred from an animal in the wild to a web-based data collection and management system, overcoming previous limitations on the quantities of data that could be transferred. The system provides an opportunity to detect unusual events as they are occurring, enabling investigation of the animal and site shortly afterwards. Although the current study was limited to bears in winter dens, we anticipate that future systems will transmit data from implantable monitors to wearable transmitters, allowing for big data transfer on non-stationary animals.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"14 ","pages":"13"},"PeriodicalIF":0.0,"publicationDate":"2014-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-014-0013-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32900057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acetate transiently inhibits myocardial contraction by increasing mitochondrial calcium uptake.","authors":"James F Schooley,&nbsp;Aryan M A Namboodiri,&nbsp;Rachel T Cox,&nbsp;Rolf Bünger,&nbsp;Thomas P Flagg","doi":"10.1186/s12899-014-0012-2","DOIUrl":"https://doi.org/10.1186/s12899-014-0012-2","url":null,"abstract":"<p><strong>Background: </strong>There is a close relationship between cardiovascular disease and cardiac energy metabolism, and we have previously demonstrated that palmitate inhibits myocyte contraction by increasing Kv channel activity and decreasing the action potential duration. Glucose and long chain fatty acids are the major fuel sources supporting cardiac function; however, cardiac myocytes can utilize a variety of substrates for energy generation, and previous studies demonstrate the acetate is rapidly taken up and oxidized by the heart. In this study, we tested the effects of acetate on contractile function of isolated mouse ventricular myocytes.</p><p><strong>Results: </strong>Acute exposure of myocytes to 10 mM sodium acetate caused a marked, but transient, decrease in systolic sarcomere shortening (1.49 ± 0.20% vs. 5.58 ± 0.49% in control), accompanied by a significant increase in diastolic sarcomere length (1.81 ± 0.01 μm vs. 1.77 ± 0.01 μm in control), with a near linear dose response in the 1-10 mM range. Unlike palmitate, acetate caused no change in action potential duration; however, acetate markedly increased mitochondrial Ca(2+) uptake. Moreover, pretreatment of cells with the mitochondrial Ca(2+) uptake blocker, Ru-360 (10 μM), markedly suppressed the effect of acetate on contraction.</p><p><strong>Conclusions: </strong>Lehninger and others have previously demonstrated that the anions of weak aliphatic acids such as acetate stimulate Ca(2+) uptake in isolated mitochondria. Here we show that this effect of acetate appears to extend to isolated cardiac myocytes where it transiently modulates cell contraction.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"14 ","pages":"12"},"PeriodicalIF":0.0,"publicationDate":"2014-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-014-0012-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32893343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of novel Kirrel3 gene splice variants in adult human skeletal muscle.","authors":"Peter Joseph Durcan,&nbsp;Johannes D Conradie,&nbsp;Mari Van deVyver,&nbsp;Kathryn Helen Myburgh","doi":"10.1186/s12899-014-0011-3","DOIUrl":"https://doi.org/10.1186/s12899-014-0011-3","url":null,"abstract":"<p><strong>Background: </strong>Multiple cell types including trophoblasts, osteoclasts and myoblasts require somatic cell fusion events as part of their physiological functions. In Drosophila Melanogaster the paralogus type 1 transmembrane receptors and members of the immunoglobulin superfamily Kin of Irre (Kirre) and roughest (Rst) regulate myoblast fusion during embryonic development. Present within the human genome are three homologs to Kirre termed Kin of Irre like (Kirrel) 1, 2 and 3. Currently it is unknown if Kirrel3 is expressed in adult human skeletal muscle.</p><p><strong>Results: </strong>We investigated (using PCR and Western blot) Kirrel3 in adult human skeletal muscle samples taken at rest and after mild exercise induced muscle damage. Kirrel3 mRNA expression was verified by sequencing and protein presence via blotting with 2 different anti-Kirrel3 protein antibodies. Evidence for three alternatively spliced Kirrel3 mRNA transcripts in adult human skeletal muscle was obtained. Kirrel3 mRNA in adult human skeletal muscle was detected at low or moderate levels, or not at all. This sporadic expression suggests that Kirrel3 is expressed in a pulsatile manner. Several anti Kirrel3 immunoreactive proteins were detected in all adult human skeletal muscle samples analysed and results suggest the presence of different isoforms or posttranslational modification, or both.</p><p><strong>Conclusion: </strong>The results presented here demonstrate for the first time that there are at least 3 splice variants of Kirrel3 expressed in adult human skeletal muscle, two of which have never previously been identified in human muscle. Importantly, mRNA of all splice variants was not always present, a finding with potential physiological relevance. These initial discoveries highlight the need for more molecular and functional studies to understand the role of Kirrel3 in human skeletal muscle.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"14 ","pages":"11"},"PeriodicalIF":0.0,"publicationDate":"2014-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-014-0011-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32890757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"White-nose syndrome initiates a cascade of physiologic disturbances in the hibernating bat host.","authors":"Michelle L Verant,&nbsp;Carol U Meteyer,&nbsp;John R Speakman,&nbsp;Paul M Cryan,&nbsp;Jeffrey M Lorch,&nbsp;David S Blehert","doi":"10.1186/s12899-014-0010-4","DOIUrl":"https://doi.org/10.1186/s12899-014-0010-4","url":null,"abstract":"<p><strong>Background: </strong>The physiological effects of white-nose syndrome (WNS) in hibernating bats and ultimate causes of mortality from infection with Pseudogymnoascus (formerly Geomyces) destructans are not fully understood. Increased frequency of arousal from torpor described among hibernating bats with late-stage WNS is thought to accelerate depletion of fat reserves, but the physiological mechanisms that lead to these alterations in hibernation behavior have not been elucidated. We used the doubly labeled water (DLW) method and clinical chemistry to evaluate energy use, body composition changes, and blood chemistry perturbations in hibernating little brown bats (Myotis lucifugus) experimentally infected with P. destructans to better understand the physiological processes that underlie mortality from WNS.</p><p><strong>Results: </strong>These data indicated that fat energy utilization, as demonstrated by changes in body composition, was two-fold higher for bats with WNS compared to negative controls. These differences were apparent in early stages of infection when torpor-arousal patterns were equivalent between infected and non-infected animals, suggesting that P. destructans has complex physiological impacts on its host prior to onset of clinical signs indicative of late-stage infections. Additionally, bats with mild to moderate skin lesions associated with early-stage WNS demonstrated a chronic respiratory acidosis characterized by significantly elevated dissolved carbon dioxide, acidemia, and elevated bicarbonate. Potassium concentrations were also significantly higher among infected bats, but sodium, chloride, and other hydration parameters were equivalent to controls.</p><p><strong>Conclusions: </strong>Integrating these novel findings on the physiological changes that occur in early-stage WNS with those previously documented in late-stage infections, we propose a multi-stage disease progression model that mechanistically describes the pathologic and physiologic effects underlying mortality of WNS in hibernating bats. This model identifies testable hypotheses for better understanding this disease, knowledge that will be critical for defining effective disease mitigation strategies aimed at reducing morbidity and mortality that results from WNS.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"14 ","pages":"10"},"PeriodicalIF":0.0,"publicationDate":"2014-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-014-0010-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32890850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential role of STIM1 and STIM2 during transient inward (T in) current generation and the maturation process in the Xenopus oocyte.","authors":"Barbara Serrano-Flores,&nbsp;Edith Garay,&nbsp;Francisco G Vázquez-Cuevas,&nbsp;Rogelio O Arellano","doi":"10.1186/s12899-014-0009-x","DOIUrl":"https://doi.org/10.1186/s12899-014-0009-x","url":null,"abstract":"<p><strong>Background: </strong>The Xenopus oocyte is a useful cell model to study Ca2+ homeostasis and cell cycle regulation, two highly interrelated processes. Here, we used antisense oligonucleotides to investigate the role in the oocyte of stromal interaction molecule (STIM) proteins that are fundamental elements of the store-operated calcium-entry (SOCE) phenomenon, as they are both sensors for Ca2+ concentration in the intracellular reservoirs as well as activators of the membrane channels that allow Ca2+ influx.</p><p><strong>Results: </strong>Endogenous STIM1 and STIM2 expression was demonstrated, and their synthesis was knocked down 48-72 h after injecting oocytes with specific antisense sequences. Selective elimination of their mRNA and protein expression was confirmed by PCR and Western blot analysis, and we then evaluated the effect of their absence on two endogenous responses: the opening of SOC channels elicited by G protein-coupled receptor (GPCR)-activated Ca2+ release, and the process of maturation stimulated by progesterone. Activation of SOC channels was monitored electrically by measuring the T in response, a Ca2+-influx-dependent Cl- current, while maturation was assessed by germinal vesicle breakdown (GVBD) scoring and electrophysiology.</p><p><strong>Conclusions: </strong>It was found that STIM2, but not STIM1, was essential in both responses, and T in currents and GVBD were strongly reduced or eliminated in cells devoid of STIM2; STIM1 knockdown had no effect on the maturation process, but it reduced the T in response by 15 to 70%. Thus, the endogenous SOCE response in Xenopus oocytes depended mainly on STIM2, and its expression was necessary for entry into meiosis induced by progesterone.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"14 ","pages":"9"},"PeriodicalIF":0.0,"publicationDate":"2014-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-014-0009-x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32817271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Longevity of Daphnia and the attenuation of stress responses by melatonin.","authors":"Anke Schwarzenberger,&nbsp;Mark Christjani,&nbsp;Alexander Wacker","doi":"10.1186/s12899-014-0008-y","DOIUrl":"https://doi.org/10.1186/s12899-014-0008-y","url":null,"abstract":"<p><strong>Background: </strong>The widespread occurrence of melatonin in prokaryotes as well as eukaryotes indicates that this indoleamine is considerably old. This high evolutionary age has led to the development of diverse functions of melatonin in different organisms, such as the detoxification of reactive oxygen species and anti-stress effects. In insects, i.e. Drosophila, the addition of melatonin has also been shown to increase the life span of this arthropod, probably by reducing age-related increasing oxidative stress. Although the presence of melatonin was recently found to exist in the ecological and toxicological model organism Daphnia, its function in this cladoceran has thus far not been addressed. Therefore, we challenged Daphnia with three different stressors in order to investigate potential stress-response attenuating effects of melatonin. i) Female and male daphnids were exposed to melatonin in a longevity experiment, ii) Daphnia were confronted with stress signals from the invertebrate predator Chaoborus sp., and iii) Daphnia were grown in high densities, i.e. under crowding-stress conditions.</p><p><strong>Results: </strong>In our experiments we were able to show that longevity of daphnids was not affected by melatonin. Therefore, age-related increasing oxidative stress was probably not compensated by added melatonin. However, melatonin significantly attenuated Daphnia's response to acute predator stress, i.e. the formation of neckteeth which decrease the ability of the gape-limited predator Chaoborus sp. to handle their prey. In addition, melatonin decreased the extent of crowding-related production of resting eggs of Daphnia.</p><p><strong>Conclusions: </strong>Our results confirm the effect of melatonin on inhibition of stress-signal responses of Daphnia. Until now, only a single study demonstrated melatonin effects on behavioral responses due to vertebrate kairomones, whereas we clearly show a more general effect of melatonin: i) on morphological predator defense induced by an invertebrate kairomone and ii) on life history characteristics transmitted by chemical cues from conspecifics. Therefore, we could generally confirm that melatonin plays a role in the attenuation of responses to different stressors in Daphnia.</p>","PeriodicalId":35905,"journal":{"name":"BMC Physiology","volume":"14 ","pages":"8"},"PeriodicalIF":0.0,"publicationDate":"2014-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12899-014-0008-y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32795256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}