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Mäkinen EE, Lensu S, Wikgren J, Pekkala S, Koch LG, Britton SL, Nokia MS. Intrinsic running capacity associates with hippocampal electrophysiology and long-term potentiation in rats. Neurosci Lett 2024; 823:137665. [PMID: 38301912 DOI: 10.1016/j.neulet.2024.137665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 01/11/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024]
Abstract
Good aerobic and metabolic fitness associates with better cognitive performance and brain health. Conversely, poor metabolic health predisposes to neurodegenerative diseases. Our previous findings indicate that rats selectively bred for Low Capacity for Running (LCR) show less synaptic plasticity and more inflammation in the hippocampus and perform worse in tasks requiring flexible cognition than rats bred for High Capacity for Running (HCR). Here we aimed to determine whether hippocampal electrophysiological activity related to learning and memory would be impaired in LCR compared to HCR rats. We also studied whether an exercise intervention could even out the possible differences. We conducted in vivo recordings from the dorsal hippocampus under terminal urethane anesthesia in middle-aged sedentary males and female rats, and in females allowed to access running wheels for 6 weeks. Our results indicate stronger long-term potentiation (LTP) in the CA3-CA1 synapse in HCR than LCR rats, and in female than male rats. Compared to LCR rats, HCR rats had more dentate spikes and more gamma epochs, the occurrence of which also correlated positively with the magnitude of LTP. Voluntary running reduced the differences between female LCR and HCR rats. In conclusion, low innate fitness links to reduced hippocampal function and plasticity which can seems to improve with voluntary aerobic exercise even in middle age.
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Affiliation(s)
- Elina E Mäkinen
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
| | - Sanna Lensu
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland; Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
| | - Jan Wikgren
- Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
| | - Satu Pekkala
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Lauren G Koch
- Department of Physiology and Pharmacology, The University of Toledo, Toledo, OH, USA
| | - Steven L Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Miriam S Nokia
- Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
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Mäkinen E, Wikgren J, Pekkala S, Koch LG, Britton SL, Nokia MS, Lensu S. Genotype determining aerobic exercise capacity associates with behavioral plasticity in middle-aged rats. Behav Brain Res 2023; 443:114331. [PMID: 36774999 DOI: 10.1016/j.bbr.2023.114331] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/20/2023] [Accepted: 02/04/2023] [Indexed: 02/12/2023]
Abstract
Good aerobic fitness associates positively with cognitive performance and brain health and conversely, low aerobic fitness predisposes to neurodegenerative diseases. To study how genotype together with exercise, started at older age, affects brain and behavior, we utilized rats that differ in inherited aerobic fitness. Rats bred for Low Capacity for Running (LCR) are shown to display less synaptic plasticity and more inflammation in the hippocampus and perform worse than rats bred for a High Capacity for Running (HCR) in tasks requiring flexible cognition. Here we used middle-aged (∼ 16 months) HCR and LCR rats to study how genotype and sex associate with anxiety and neural information filtering, termed sensory gating. Further, we assessed how inherited aerobic capacity associates with hippocampus-dependent learning, measured with contextual fear conditioning task. In females, we also investigated the effects of voluntary wheel running (5 weeks) on these characteristics. Our results indicate that independent of sex or voluntary running, HCR rats were more anxious in open-field tasks, exhibited lower sensory gating and learned more efficiently in contextual fear conditioning task than LCR rats. Voluntary running did not markedly affect innate behavior but slightly decreased the differences between female LCR and HCR rats in fear learning. In conclusion, inherited fitness seems to determine cognitive and behavioral traits independent of sex. Although the traits proved to be rather resistant to change at adult age, learning was slightly improved following exercise in LCR females, prone to obesity and poor fitness.
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Affiliation(s)
- Elina Mäkinen
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
| | - Jan Wikgren
- Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
| | - Satu Pekkala
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Lauren G Koch
- Department of Physiology and Pharmacology, The University of Toledo, OH, USA
| | - Steven L Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, USA; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, USA
| | - Miriam S Nokia
- Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
| | - Sanna Lensu
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland; Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
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3
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Wikgren J, Nokia MS, Mäkinen E, Koch LG, Britton SL, Kainulainen H, Lensu S. Rats with elevated genetic risk for metabolic syndrome exhibit cognitive deficiencies when young. Physiol Behav 2021; 236:113417. [PMID: 33838202 DOI: 10.1016/j.physbeh.2021.113417] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 03/17/2021] [Accepted: 04/05/2021] [Indexed: 01/26/2023]
Abstract
Metabolic syndrome (MetS) is a known risk factor for cognitive decline. Using polygenic rat models selectively bred for high and low intrinsic exercise capacity and simultaneously modelling as low and high innate risk factor for MetS respectively, we have previously shown that adult animals with lower exercise capacity/higher MetS risk perform poorly in tasks requiring flexible cognition. However, it is not known whether these deficits in cognition are present already at young age. Also, it is unclear whether the high risk genome is related also to lower-level cognition, such as sensory gating measured as prepulse inhibition. In this study, young and adult (5-8 weeks and ~9 months) rats selectively bred for 36 generations as High-Capacity Runners (HCR) or Low-Capacity Runners (LCR) were tested for behavior in an open field task, modulation of startle reflex, and spatial learning in a T-maze. HCR rats were more active in the open field than LCR rats independent of age. Responses to the startle stimulus habituated to the same extent in LCR compared to HCR rats when young, but as adults, stronger habituation was seen in the HCR animals. The prepulse inhibition of startle response was equally strong in young HCR and LCR animals but the effect was shorter lasting in HCR animals. In T-maze, adult HCR animals unexpectedly showed attenuated learning, but we interpret this finding to stem from differences in motivation rather than learning ability. Overall, in the LCR rats with the risk genome for poor aerobic fitness and MetS, indications of compromised cognitive function are present already at a young age.
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Affiliation(s)
- Jan Wikgren
- Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland.
| | - Miriam S Nokia
- Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
| | - Elina Mäkinen
- Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
| | - Lauren G Koch
- Department of Physiology and Pharmacology, Center for Hypertension and Personalized Medicine, The University of Toledo College of Medicine & Life Sciences, Toledo, OH, 2801 W. Bancroft, Toledo OH 43606-3390, USA
| | - Steven L Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, 1500 E Medical Center Drive, Ann Arbor, MI 48109-5048, USA; Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, 7744 MS II, 1137 E, Catherine St., Ann Arbor, MI 48109-5622, USA
| | - Heikki Kainulainen
- Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
| | - Sanna Lensu
- Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland; Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
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Mitochondrial health is enhanced in rats with higher vs. lower intrinsic exercise capacity and extended lifespan. NPJ Aging Mech Dis 2021; 7:1. [PMID: 33398019 PMCID: PMC7782588 DOI: 10.1038/s41514-020-00054-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 11/24/2020] [Indexed: 12/03/2022] Open
Abstract
The intrinsic aerobic capacity of an organism is thought to play a role in aging and longevity. Maximal respiratory rate capacity, a metabolic performance measure, is one of the best predictors of cardiovascular- and all-cause mortality. Rats selectively bred for high-(HCR) vs. low-(LCR) intrinsic running-endurance capacity have up to 31% longer lifespan. We found that positive changes in indices of mitochondrial health in cardiomyocytes (respiratory reserve, maximal respiratory capacity, resistance to mitochondrial permeability transition, autophagy/mitophagy, and higher lipids-over-glucose utilization) are uniformly associated with the extended longevity in HCR vs. LCR female rats. Cross-sectional heart metabolomics revealed pathways from lipid metabolism in the heart, which were significantly enriched by a select group of strain-dependent metabolites, consistent with enhanced lipids utilization by HCR cardiomyocytes. Heart–liver–serum metabolomics further revealed shunting of lipidic substrates between the liver and heart via serum during aging. Thus, mitochondrial health in cardiomyocytes is associated with extended longevity in rats with higher intrinsic exercise capacity and, probably, these findings can be translated to other populations as predictors of outcomes of health and survival.
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Hambrecht-Wiedbusch VS, Gabel M, Liu LJ, Imperial JP, Colmenero AV, Vanini G. Preemptive Caffeine Administration Blocks the Increase in Postoperative Pain Caused by Previous Sleep Loss in the Rat: A Potential Role for Preoptic Adenosine A2A Receptors in Sleep-Pain Interactions. Sleep 2018; 40:4037126. [PMID: 28934532 DOI: 10.1093/sleep/zsx116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Sleep and pain are reciprocally related, but the precise mechanisms underlying this relationship are poorly understood. This study used a rat model of surgical pain to examine the effect of previous sleep loss on postoperative pain and tested the hypothesis that preoptic adenosinergic mechanisms regulate sleep-pain interactions. Relative to ad libitum sleep, 6 hours of total sleep deprivation prior to a surgical incision significantly enhanced postoperative mechanical hypersensitivity in the affected paw and prolonged the time to recovery from surgery. There were no sex-specific differences in these measures. There were also no changes in adrenocorticotropic hormone and corticosterone levels after sleep deprivation, suggesting that this effect was not mediated by the stress associated with the sleep perturbation. Systemic administration of the nonselective adenosine receptor antagonist caffeine at the onset of sleep deprivation prevented the sleep deprivation-induced increase in postoperative hypersensitivity. Microinjection of the adenosine A2A receptor antagonist ZM 241385 into the median preoptic nucleus (MnPO) blocked the increase in surgical pain levels and duration caused by prior sleep deprivation and eliminated the thermal hyperalgesia induced by sleep deprivation in a group of nonoperated (i.e., without surgical incision) rats. These data show that even a brief sleep disturbance prior to surgery worsens postoperative pain and are consistent with our hypothesis that adenosine A2A receptors in the MnPO contribute to regulate these sleep-pain interactions.
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Affiliation(s)
| | - Maya Gabel
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | - Linda J Liu
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | - John P Imperial
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | | | - Giancarlo Vanini
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
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6
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Cooper MA, Jack MM, Ryals JM, Hayley P, Escher T, Koch LG, Britton SL, Raupp SM, Winter MK, McCarson KE, Geiger PC, Thyfault JP, Wright DE. Rats bred for low and high running capacity display alterations in peripheral tissues and nerves relevant to neuropathy and pain. Brain Behav 2017; 7:e00780. [PMID: 29075557 PMCID: PMC5651381 DOI: 10.1002/brb3.780] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/04/2017] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION Diet and activity are recognized as modulators of nervous system disease, including pain. Studies of exercise consistently reveal a benefit on pain. This study focused on female rats to understand differences related to metabolic status and peripheral nerve function in females. METHODS Here, we investigated parameters of peripheral nerve function relevant to pain in rats selectively bred for high (high-capacity runners; HCR) or low endurance exercise capacity (low-capacity runners; LCR) resulting in divergent intrinsic aerobic capacities and susceptibility for metabolic conditions. RESULTS LCR female rats have reduced mechanical sensitivity, higher intraepidermal nerve fiber density and TrkA-positive epidermal axons, increased numbers of Langerhans and mast cells in cutaneous tissues, and a higher fat content despite similar overall body weights compared to female HCR rats. Sensory and motor nerve conduction velocities, thermal sensitivity, and mRNA expression of selected genes relevant to peripheral sensation were not different. CONCLUSIONS These results suggest that aerobic capacity and metabolic status influence sensory sensitivity and aspects of inflammation in peripheral tissues that could lead to poor responses to tissue damage and painful stimuli. The LCR and HCR rats should prove useful as models to assess how the metabolic status impacts pain.
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Affiliation(s)
- Michael A Cooper
- Department of Anatomy and Cell Biology University of Kansas Medical Center Kansas City KS
| | - Megan M Jack
- Department of Neurosurgery University of Kansas Medical Center Kansas City KS
| | - Janelle M Ryals
- Department of Anatomy and Cell Biology University of Kansas Medical Center Kansas City KS
| | - Page Hayley
- Department of Anatomy and Cell Biology University of Kansas Medical Center Kansas City KS
| | - Taylor Escher
- Department of Anatomy and Cell Biology University of Kansas Medical Center Kansas City KS
| | - Lauren G Koch
- Department of Anesthesiology University of Michigan Ann Arbor MI
| | - Steven L Britton
- Department of Anesthesiology University of Michigan Ann Arbor MI.,Department of Molecular and Integrative Physiology University of Michigan Ann Arbor MI
| | - Shelby M Raupp
- Department of Anesthesiology University of Michigan Ann Arbor MI
| | - Michelle K Winter
- Kansas Intellectual and Developmental Disabilities Research University of Kansas Medical Center Kansas City KS
| | - Kenneth E McCarson
- Department of Pharmacology Toxicology and Therapeutics University of Kansas Medical Center Kansas City KS
| | - Paige C Geiger
- Department of Molecular and Integrative Physiology University of Kansas Medical Center Kansas City KS
| | - John P Thyfault
- Department of Molecular and Integrative Physiology University of Kansas Medical Center Kansas City KS.,Research Service Kansas City Medical Center Kansas City MO
| | - Douglas E Wright
- Department of Anatomy and Cell Biology University of Kansas Medical Center Kansas City KS
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7
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Vanini G. Sleep Deprivation and Recovery Sleep Prior to a Noxious Inflammatory Insult Influence Characteristics and Duration of Pain. Sleep 2016; 39:133-42. [PMID: 26237772 DOI: 10.5665/sleep.5334] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/28/2015] [Indexed: 12/26/2022] Open
Abstract
STUDY OBJECTIVES Insufficient sleep and chronic pain are public health epidemics. Sleep loss worsens pain and predicts the development of chronic pain. Whether previous, acute sleep loss and recovery sleep determine pain levels and duration remains poorly understood. This study tested whether acute sleep deprivation and recovery sleep prior to formalin injection alter post-injection pain levels and duration. METHODS Male Sprague-Dawley rats (n = 48) underwent sleep deprivation or ad libitum sleep for 9 hours. Thereafter, rats received a subcutaneous injection of formalin or saline into a hind paw. In the recovery sleep group, rats were allowed 24 h between sleep deprivation and the injection of formalin. Mechanical and thermal nociception were assessed using the von Frey test and Hargreaves' method. Nociceptive measures were performed at 1, 3, 7, 10, 14, 17 and 21 days post-injection. RESULTS Formalin caused bilateral mechanical hypersensitivity (allodynia) that persisted for up to 21 days post-injection. Sleep deprivation significantly enhanced bilateral allodynia. There was a synergistic interaction when sleep deprivation preceded a formalin injection. Rats allowed a recovery sleep period prior to formalin injection developed allodynia only in the injected limb, with higher mechanical thresholds (less allodynia) and a shorter recovery period. There were no persistent changes in thermal nociception. CONCLUSION The data suggest that acute sleep loss preceding an inflammatory insult enhances pain and can contribute to chronic pain. The results encourage studies in a model of surgical pain to test whether enhancing sleep reduces pain levels and duration.
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Affiliation(s)
- Giancarlo Vanini
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
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8
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Watson SL, Watson CJ, Baghdoyan HA, Lydic R. Adenosine A₁ receptors in mouse pontine reticular formation modulate nociception only in the presence of systemic leptin. Neuroscience 2014; 275:531-9. [PMID: 24976513 PMCID: PMC4143377 DOI: 10.1016/j.neuroscience.2014.06.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Revised: 06/09/2014] [Accepted: 06/12/2014] [Indexed: 01/07/2023]
Abstract
Human obesity is associated with increased leptin levels and pain, but the specific brain regions and neurochemical mechanisms underlying this association remain poorly understood. This study used adult male C57BL/6J (B6, n=14) mice and leptin-deficient, obese B6.Cg-Lep(ob)/J (obese, n=10) mice to evaluate the hypothesis that nociception is altered by systemic leptin levels and by adenosine A₁ receptors in the pontine reticular formation. Nociception was quantified as paw withdrawal latency (PWL) in s after onset of a thermal stimulus. PWL was converted to percent maximum possible effect (%MPE). After obtaining baseline PWL measures, the pontine reticular formation was microinjected with saline (control), three concentrations of the adenosine A₁ receptor agonist N(6)-p-sulfophenyladenosine (SPA), or super-active mouse leptin receptor antagonist (SMLA) followed by SPA 15 min later, and PWL was again quantified. In obese, leptin-deficient mice, nociception was quantified before and during leptin replacement via subcutaneous osmotic pumps. SPA was administered into the pontine reticular formation of leptin-replaced mice and PWL testing was repeated. During baseline (before vehicle or SPA administration), PWL was significantly (p=0.0013) lower in leptin-replaced obese mice than in B6 mice. Microinjecting SPA into the pontine reticular formation of B6 mice caused a significant (p=0.0003) concentration-dependent increase in %MPE. SPA also significantly (p<0.05) increased %MPE in B6 mice and in leptin-replaced obese mice, but not in leptin-deficient obese mice. Microinjection of SMLA into the pontine reticular formation before SPA did not alter PWL. The results show for the first time that pontine reticular formation administration of the adenosine A₁ receptor agonist SPA produced antinociception only in the presence of systemic leptin. The concentration-response data support the interpretation that adenosine A₁ receptors localized to the pontine reticular formation significantly alter nociception.
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Affiliation(s)
- S L Watson
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA
| | - C J Watson
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA
| | - H A Baghdoyan
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA
| | - R Lydic
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA.
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9
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Filbey WA, Sanford DT, Baghdoyan HA, Koch LG, Britton SL, Lydic R. Eszopiclone and dexmedetomidine depress ventilation in obese rats with features of metabolic syndrome. Sleep 2014; 37:871-80. [PMID: 24790265 PMCID: PMC3985114 DOI: 10.5665/sleep.3650] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
STUDY OBJECTIVES Obesity alters the therapeutic window of sedative/hypnotic drugs and increases the probability of respiratory complications. The current experiments used an established rodent model of obesity to test the hypothesis that the sedative/hypnotic drugs eszopiclone and dexmedetomidine alter ventilation differentially in obese rats compared with lean/fit rats. DESIGN This study used a within-groups/between-groups experimental design. SETTING University of Michigan. PARTICIPANTS Experiments were conducted using lean/fit rats (n = 21) and obese rats (n = 21) that have features of metabolic syndrome. INTERVENTIONS Breathing was measured with whole-body plethysmography after systemic administration of vehicle (control), the nonbenzodiazepine, benzodiazepine site agonist eszopiclone, or the alpha-2 adrenergic receptor agonist dexmedetomidine. MEASUREMENTS AND RESULTS Data were analyzed using two-way analysis of variance and appropriate post hoc comparisons. At baseline, the obese/metabolic syndrome rats had increased respiratory rates (21.6%), lower tidal volumes/body weight (-24.1%), and no differences in minute ventilation compared to lean/fit rats. In the obese rats, respiratory rate was decreased by dexmedetomidine (-29%), but not eszopiclone. In the lean and the obese rats, eszopiclone decreased tidal volume (-12%). Both sedative/hypnotic drugs caused a greater decrease in minute ventilation in the obese (-26.3%) than lean (-18%) rats. Inspiratory flow rate (VT / TI) of the obese rats was decreased by dexmedetomidine (-10.6%) and eszopiclone (-18%). Duty cycle (TI / TTOT) in both rat lines was decreased by dexmedetomidine (-16.5%) but not by eszopiclone. CONCLUSIONS Dexmedetomidine, in contrast to eszopiclone, decreased minute ventilation in the obese/metabolic syndrome rats by depressing both duty cycle and inspiratory flow rate. The results show for the first time that the obese phenotype differentially modulates the respiratory effects of eszopiclone and dexmedetomidine. These differences in breathing are consistent with previously documented differences in sleep between lean/fit and obese rats. These findings also encourage future studies of obese/metabolic syndrome rats that quantify the effect of sedative/hypnotic drugs on respiratory mechanics as well as hypoxic and hypercapnic ventilatory responses. Continued findings of favorable homology between obese humans and rodents will support the interpretation that these obese rats offer a unique animal model for mechanistic studies.
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Affiliation(s)
| | - David T. Sanford
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | | | - Lauren G. Koch
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | | | - Ralph Lydic
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
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10
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Ren YY, Overmyer KA, Qi NR, Treutelaar MK, Heckenkamp L, Kalahar M, Koch LG, Britton SL, Burant CF, Li JZ. Genetic analysis of a rat model of aerobic capacity and metabolic fitness. PLoS One 2013; 8:e77588. [PMID: 24147032 PMCID: PMC3795692 DOI: 10.1371/journal.pone.0077588] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 09/10/2013] [Indexed: 11/20/2022] Open
Abstract
Aerobic capacity is a strong predictor of all-cause mortality and can influence many complex traits. To explore the biological basis underlying this connection, we developed via artificial selection two rat lines that diverge for intrinsic (i.e. inborn) aerobic capacity and differ in risk for complex disease traits. Here we conduct the first in-depth pedigree and molecular genetic analysis of these lines, the high capacity runners (HCR) and low capacity runners (LCR). Our results show that both HCR and LCR lines maintain considerable narrow-sense heritability (h2) for the running capacity phenotype over 28 generations (h2 = 0.47 ± 0.02 and 0.43 ± 0.02, respectively). To minimize inbreeding, the lines were maintained by rotational mating. Pedigree records predict that the inbreeding coefficient increases at a rate of <1% per generation, ~37-38% slower than expected for random mating. Genome-wide 10K SNP genotype data for generations 5, 14, and 26 demonstrate substantial genomic evolution: between-line differentiation increased progressively, while within-line diversity deceased. Genome-wide average heterozygosity decreased at a rate of <1% per generation, consistent with pedigree-based predictions and confirming the effectiveness of rotational breeding. Linkage disequilibrium index r2 decreases to 0.3 at ~3 Mb, suggesting that the resolution for mapping quantitative trait loci (QTL) can be as high as 2-3 cM. To establish a test population for QTL mapping, we conducted an HCR-LCR intercross. Running capacity of the F1 population (n=176) was intermediate of the HCR and LCR parentals (28 pairs); and the F2 population (n=645) showed a wider range of phenotypic distribution. Importantly, heritability in the F0-F2 pedigree remained high (h2~0.6). These results suggest that the HCR-LCR lines can serve as a valuable system for studying genomic evolution, and a powerful resource for mapping QTL for a host of characters relevant to human health.
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Affiliation(s)
- Yu-yu Ren
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Katherine A. Overmyer
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Nathan R. Qi
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Mary K. Treutelaar
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Lori Heckenkamp
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Molly Kalahar
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Lauren G. Koch
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Steven L. Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Charles F. Burant
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Jun Z. Li
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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11
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Foley TE, Brooks LR, Gilligan LJ, Burghardt PR, Koch LG, Britton SL, Fleshner M. Brain activation patterns at exhaustion in rats that differ in inherent exercise capacity. PLoS One 2012; 7:e45415. [PMID: 23028992 PMCID: PMC3444461 DOI: 10.1371/journal.pone.0045415] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 08/22/2012] [Indexed: 11/18/2022] Open
Abstract
In order to further understand the genetic basis for variation in inherent (untrained) exercise capacity, we examined the brains of 32 male rats selectively bred for high or low running capacity (HCR and LCR, respectively). The aim was to characterize the activation patterns of brain regions potentially involved in differences in inherent running capacity between HCR and LCR. Using quantitative in situ hybridization techniques, we measured messenger ribonuclease (mRNA) levels of c-Fos, a marker of neuronal activation, in the brains of HCR and LCR rats after a single bout of acute treadmill running (7.5-15 minutes, 15° slope, 10 m/min) or after treadmill running to exhaustion (15-51 minutes, 15° slope, initial velocity 10 m/min). During verification of trait differences, HCR rats ran six times farther and three times longer prior to exhaustion than LCR rats. Running to exhaustion significantly increased c-Fos mRNA activation of several brain areas in HCR, but LCR failed to show significant elevations of c-Fos mRNA at exhaustion in the majority of areas examined compared to acutely run controls. Results from these studies suggest that there are differences in central c-Fos mRNA expression, and potential brain activation patterns, between HCR and LCR rats during treadmill running to exhaustion and these differences could be involved in the variation in inherent running capacity between lines.
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Affiliation(s)
- Teresa E. Foley
- Department of Integrative Physiology and The Center for Neuroscience, University of Colorado, Boulder, Colorado, United States of America
| | - Leah R. Brooks
- Department of Integrative Physiology and The Center for Neuroscience, University of Colorado, Boulder, Colorado, United States of America
| | - Lori J. Gilligan
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Paul R. Burghardt
- Department of Psychiatry and the Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Lauren G. Koch
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Steven L. Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Monika Fleshner
- Department of Integrative Physiology and The Center for Neuroscience, University of Colorado, Boulder, Colorado, United States of America
- * E-mail:
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Koch LG, Britton SL, Wisløff U. A rat model system to study complex disease risks, fitness, aging, and longevity. Trends Cardiovasc Med 2012; 22:29-34. [PMID: 22867966 DOI: 10.1016/j.tcm.2012.06.007] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The association between low exercise capacity and all-cause morbidity and mortality is statistically strong yet mechanistically unresolved. By connecting clinical observation with a theoretical base, we developed a working hypothesis that variation in capacity for oxygen metabolism is the central mechanistic determinant between disease and health (aerobic hypothesis). As an unbiased test, we show that two-way artificial selective breeding of rats for low and high intrinsic endurance exercise capacity also produces rats that differ for numerous disease risks, including the metabolic syndrome, cardiovascular complications, premature aging, and reduced longevity. This contrasting animal model system may prove to be translationally superior relative to more widely used simplistic models for understanding geriatric biology and medicine.
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Affiliation(s)
- Lauren Gerard Koch
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI 48109, USA.
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Wathen AB, West ES, Lydic R, Baghdoyan HA. Olanzapine causes a leptin-dependent increase in acetylcholine release in mouse prefrontal cortex. Sleep 2012; 35:315-23. [PMID: 22379237 PMCID: PMC3274332 DOI: 10.5665/sleep.1686] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
STUDY OBJECTIVES The atypical antipsychotic olanzapine is used effectively for treating symptoms of schizophrenia and bipolar disorder. Unwanted effects of olanzapine include slowing of the electroencephalogram (EEG) during wakefulness and increased circulating levels of leptin. The mechanisms underlying the desired and undesired effects of olanzapine are poorly understood. Sleep and wakefulness are modulated by acetylcholine (ACh) in the prefrontal cortex, and leptin alters cholinergic transmission. This study tested the hypothesis that olanzapine interacts with leptin to regulate ACh release in the prefrontal cortex. DESIGN Within/between subjects. SETTING University of Michigan. PATIENTS OR PARTICIPANTS Adult male C57BL/6J (B6) mice (n = 33) and B6.V-Lep(ob) (leptin-deficient) mice (n = 31). INTERVENTIONS Olanzapine was delivered to the prefrontal cortex by microdialysis. Leptin-replacement in leptin-deficient mice was achieved using subcutaneous micro-osmotic pumps. MEASUREMENTS AND RESULTS Olanzapine caused a concentration-dependent increase in ACh release in B6 and leptin-deficient mice. Olanzapine was 230-fold more potent in leptin-deficient than in B6 mice for increasing ACh release, yet olanzapine caused a 51% greater ACh increase in B6 than in leptin-deficient mice. Olanzapine had no effect on recovery time from general anesthesia. Olanzapine increased EEG power in the delta (0.5-4 Hz) range. Thus, olanzapine dissociated the normal coupling between increased cortical ACh release, increased behavioral arousal, and EEG activation. Leptin replacement significantly enhanced (75%) the olanzapine-induced increase in ACh release. CONCLUSION Replacing leptin by systemic administration restored the olanzapine-induced enhancement of ACh release in the prefrontal cortex of leptin-deficient mouse.
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Affiliation(s)
| | - Emily S. West
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
| | - Ralph Lydic
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI
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Mavanji V, Billington CJ, Kotz CM, Teske JA. Sleep and obesity: a focus on animal models. Neurosci Biobehav Rev 2012; 36:1015-29. [PMID: 22266350 DOI: 10.1016/j.neubiorev.2012.01.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 11/25/2011] [Accepted: 01/07/2012] [Indexed: 12/19/2022]
Abstract
The rapid rise in obesity prevalence in the modern world parallels a significant reduction in restorative sleep (Agras et al., 2004; Dixon et al., 2007, 2001; Gangwisch and Heymsfield, 2004; Gupta et al., 2002; Sekine et al., 2002; Vioque et al., 2000; Wolk et al., 2003). Reduced sleep time and quality increases the risk for obesity, but the underlying mechanisms remain unclear (Gangwisch et al., 2005; Hicks et al., 1986; Imaki et al., 2002; Jennings et al., 2007; Moreno et al., 2006). A majority of the theories linking human sleep disturbances and obesity rely on self-reported sleep. However, studies with objective measurements of sleep/wake parameters suggest a U-shaped relationship between sleep and obesity. Studies in animal models are needed to improve our understanding of the association between sleep disturbances and obesity. Genetic and experimenter-induced models mimicking characteristics of human obesity are now available and these animal models will be useful in understanding whether sleep disturbances determine propensity for obesity, or result from obesity. These models exhibit weight gain profiles consistently different from control animals. Thus a careful evaluation of animal models will provide insight into the relationship between sleep disturbances and obesity in humans. In this review we first briefly consider the fundamentals of sleep and key sleep disturbances, such as sleep fragmentation and excessive daytime sleepiness (EDS), observed in obese individuals. Then we consider sleep deprivation studies and the role of circadian alterations in obesity. We describe sleep/wake changes in various rodent models of obesity and obesity resistance. Finally, we discuss possible mechanisms linking sleep disturbances with obesity.
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Affiliation(s)
- Vijayakumar Mavanji
- Minnesota Obesity Prevention Training Program, School of Public Health, University of Minnesota, Minneapolis, MN, USA.
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Pal D, Walton ME, Lipinski WJ, Koch LG, Lydic R, Britton SL, Mashour GA. Determination of minimum alveolar concentration for isoflurane and sevoflurane in a rodent model of human metabolic syndrome. Anesth Analg 2011; 114:297-302. [PMID: 22167771 DOI: 10.1213/ane.0b013e31823ede22] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Morbid obesity affects the pharmacokinetics and pharmacodynamics of anesthetics, which may result in inappropriate dosing. We hypothesized that obesity significantly alters the minimum alveolar concentration (MAC) for isoflurane and sevoflurane. To test this hypothesis, we used a rodent model of human metabolic syndrome developed through artificial selection for inherent low aerobic capacity runners (LCR) and high aerobic capacity runners (HCR). The LCR rats are obese, display phenotypes homologous to those characteristic of human metabolic syndrome, and exhibit low running endurance. In contrast, HCR rats have high running endurance and are characterized by improved cardiovascular performance and overall health. METHODS Male and female LCR (n = 10) and HCR (n = 10) rats were endotracheally intubated and maintained on mechanical ventilation with either isoflurane or sevoflurane. A bracketing design was used to determine MAC; sensory stimulation was induced by tail clamping. An equilibration period of 30 minutes was provided before and between the consecutive tail clamps. Two-tailed parametric (unpaired t test) and nonparametric (Mann-Whitney test) statistics were used for the comparison of MAC between LCR and HCR rats. The data are reported as mean ± sd along with the 95% confidence interval. A P value of <0.05 was considered statistically significant. RESULTS The MAC for isoflurane in LCR rats (1.52% ± 0.13%) was similar to previously reported isoflurane-MAC for normal rats (1.51% ± 0.12%). The HCR rats showed a significantly higher isoflurane-MAC (1.90% ± 0.19%) than did the LCR rats (1.52% ± 0.13%) (P = 0.0001). The MAC for sevoflurane was not significantly different between LCR and HCR rats and was similar to the previously published sevoflurane-MAC for normal rats (2.4% ± 0.30%). There was no influence of sex on the MAC of either isoflurane or sevoflurane. CONCLUSION Obesity and associated comorbidities do not affect anesthetic requirements as measured by MAC in a rodent model of metabolic syndrome. By contrast, high aerobic capacity is associated with a higher MAC for isoflurane and may be a risk factor for subtherapeutic dosing.
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Affiliation(s)
- Dinesh Pal
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109-5048, USA
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