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Riggle JP, Kay LM, Onishi KG, Falk DT, Smarr BL, Zucker I, Prendergast BJ. Modified Wavelet Analyses Permit Quantification of Dynamic Interactions Between Ultradian and Circadian Rhythms. J Biol Rhythms 2022; 37:631-654. [PMID: 36380564 PMCID: PMC11024927 DOI: 10.1177/07487304221128652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Circadian rhythms provide daily temporal structure to cellular and organismal biological processes, ranging from gene expression to cognition. Higher-frequency (intradaily) ultradian rhythms are similarly ubiquitous but have garnered far less empirical study, in part because of the properties that define them-multimodal periods, non-stationarity, circadian harmonics, and diurnal modulation-pose challenges to their accurate and precise quantification. Wavelet analyses are ideally suited to address these challenges, but wavelet-based measurement of ultradian rhythms has remained largely idiographic. Here, we describe novel analytical approaches, based on discrete and continuous wavelet transforms, which permit quantification of rhythmic power distribution across a broad ultradian spectrum, as well as precise identification of period within empirically determined ultradian bands. Moreover, the aggregation of normalized wavelet matrices allows group-level analyses of experimental treatments, thereby circumventing limitations of idiographic approaches. The accuracy and precision of these wavelet analyses were validated using in silico and in vivo models with known ultradian features. Experiments in male and female mice yielded robust and repeatable measures of ultradian period and power in home cage locomotor activity, confirming and extending reports of ultradian rhythm modulation by sex, gonadal hormones, and circadian entrainment. Seasonal changes in day length modulated ultradian period and power, and exerted opposite effects in the light and dark phases of the 24 h day, underscoring the importance of evaluating ultradian rhythms with attention to circadian phase. Sex differences in ultradian rhythms were more prominent at night and depended on gonadal hormones in male mice. Thus, relatively straightforward modifications to the wavelet procedure allowed quantification of ultradian rhythms with appropriate time-frequency resolution, generating accurate, and repeatable measures of period and power which are suitable for group-level analyses. These analytical tools may afford deeper understanding of how ultradian rhythms are generated and respond to interoceptive and exteroceptive cues.
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Affiliation(s)
- Jonathan P. Riggle
- Department of Psychology and Institute for Mind and Biology, The University of Chicago, Chicago, Illinois
- Department of Physiology, University of California, San Francisco, San Francisco, California
| | - Leslie M. Kay
- Department of Psychology and Institute for Mind and Biology, The University of Chicago, Chicago, Illinois
- Committee on Neurobiology, The University of Chicago, Chicago, Illinois
- Committee on Computational Neuroscience, The University of Chicago, Chicago, Illinois
| | - Kenneth G. Onishi
- Department of Psychology and Institute for Mind and Biology, The University of Chicago, Chicago, Illinois
| | - David T. Falk
- Department of Psychology and Institute for Mind and Biology, The University of Chicago, Chicago, Illinois
| | - Benjamin L. Smarr
- Department of Bioengineering and the Halicioğlu Data Science Institute, University of California, San Diego, La Jolla, California
| | - Irving Zucker
- Department of Psychology, University of California, Berkeley, Berkeley, California
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California
| | - Brian J. Prendergast
- Department of Psychology and Institute for Mind and Biology, The University of Chicago, Chicago, Illinois
- Committee on Neurobiology, The University of Chicago, Chicago, Illinois
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Kavanagh GS, Tadi J, Balkenhol SM, Kauffman AS, Maloney SK, Smith JT. Kisspeptin impacts on circadian and ultradian rhythms of core body temperature: Evidence in kisspeptin receptor knockout and kisspeptin knockdown mice. Mol Cell Endocrinol 2022; 542:111530. [PMID: 34896241 PMCID: PMC9907773 DOI: 10.1016/j.mce.2021.111530] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 12/02/2021] [Accepted: 12/06/2021] [Indexed: 01/26/2023]
Abstract
Kisspeptin is vital for the regulation of both fertility and metabolism. Kisspeptin receptor (Kiss1r) knockout (KO) mice exhibit increased adiposity and reduced energy expenditure in adulthood. Kiss1r mRNA is expressed in brown adipose tissue (BAT) and Kiss1r KO mice exhibit reduced Ucp1 mRNA in BAT and impaired thermogenesis. We hypothesised that mice with diminished kisspeptin signalling would exhibit reduced core body temperature (Tc) and altered dynamics of circadian and ultradian rhythms of Tc. Tc was recorded every 15-min over 14-days in gonadectomised wild-type (WT), Kiss1r KO, and also Kiss1-Cre (95% reduction in Kiss1 transcription) mice. Female Kiss1r KOs had higher adiposity and lower Ucp1 mRNA in BAT than WTs. No change was detected in Kiss1-Cre mice. Mean Tc during the dark phase was lower in female Kiss1r KOs versus WTs, but not Kiss1-Cre mice. Female Kiss1r KOs had a lower mesor and amplitude of the circadian rhythm of Tc than did WTs. In WT mice, there were more episodic ultradian events (EUEs) of Tc during the dark phase than the light phase, but this measure was similar between dark and light phases in Kiss1r KO and Kiss1-Cre mice. The amplitude of EUEs was higher in the dark phase in female Kiss1r KO and male Kiss1-Cre mice. Given the lack of clear metabolic phenotype in Kiss1-Cre mice, 5% of Kiss1 transcription may be sufficient for proper metabolic control, as was shown for fertility. Moreover, the observed alterations in Tc suggest that kisspeptin has a role in circadian and ultradian rhythm-driven pathways.
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Affiliation(s)
- Georgia S Kavanagh
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Jason Tadi
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Sydney M Balkenhol
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Alexander S Kauffman
- Department of OBGYN and Reproductive Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Shane K Maloney
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Jeremy T Smith
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.
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Abstract
In epilepsy research, the analysis of rodent electroencephalogram (EEG) has been performed by many laboratories with a variety of techniques. However, the acquisition and basic analysis of rodent EEG have only recently been standardized. Since a number of software platforms and increased computational power have become widely available, advanced rodent EEG analysis is now more accessible to investigators working with rodent models of epilepsy. In this review, the approach to the analysis of rodent EEG will be examined, including the evaluation of both epileptiform and background activity. Major caveats when employing these analyses, cellular and circuit-level correlates of EEG changes, and important differences between rodent and human EEG are also reviewed. The currently available techniques show great promise in gaining a deeper understanding of the complexities hidden within the EEG in rodent models of epilepsy.
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Affiliation(s)
- Atul Maheshwari
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
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4
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Su J, Li Z, Yamashita A, Kusumoto-Yoshida I, Isomichi T, Hao L, Kuwaki T. Involvement of the Nucleus Accumbens in Chocolate-induced Cataplexy. Sci Rep 2020; 10:4958. [PMID: 32188934 PMCID: PMC7080740 DOI: 10.1038/s41598-020-61823-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 03/04/2020] [Indexed: 11/09/2022] Open
Abstract
Happiness is key for both mental and physical well-being. To further understand the brain mechanisms involved, we utilized the cataplexy that occurs in narcoleptic animal models as a quantitative behavioral measure because it is triggered by actions associated with happiness, such as laughter in humans and palatable foods in mice. Here we report that the rostral part of the nucleus accumbens (NAc) shell is strongly activated during the beginning of chocolate-induced cataplexy in orexin neuron-ablated mice. We made a local lesion in the NAc using ibotenic acid and observed the animals' behavior. The number of cataplexy bouts was negatively correlated to the lesion size. We also examined the hedonic response to palatable food by measuring the number of tongue protrusions in response to presentation of honey, which was also found to be negatively correlated to the lesion size. Next, we used clozapine N-oxide to either activate or inactivate the NAc through viral DREADD expression. As expected, the number of cataplexy bouts increased with activation and decreased with inactivation, and saline control injections showed no changes. Hedonic response in the DREADD experiment varied and showed both increases and decreases across mice. These results demonstrated that the rostral part of the NAc plays a crucial role in triggering cataplexy and hedonic orofacial movements. Since the NAc is also implicated in motivated behavior, we propose that the NAc is one of the key brain structures involved in happiness and is a driving force for positive emotion-related behaviors.
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Affiliation(s)
- Jingyang Su
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Zhi Li
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Akira Yamashita
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Ikue Kusumoto-Yoshida
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Takuto Isomichi
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Liying Hao
- Department of Pharmaceutical Toxicology, School of Pharmacy, China Medical University, Shenyang, China
| | - Tomoyuki Kuwaki
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
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Antipov A, Brizuela M, Blessing WW, Ootsuka Y. Alpha 2-adrenergic receptor agonists prevent emotional hyperthermia. Brain Res 2020; 1732:146678. [PMID: 31981679 DOI: 10.1016/j.brainres.2020.146678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/15/2020] [Accepted: 01/20/2020] [Indexed: 01/31/2023]
Abstract
Emotionally significant stimuli, including potential threats from the external environment, trigger an increase in body temperature, a response known as emotional hyperthermia. Sympathetically-mediated brown adipose tissue (BAT) thermogenesis contributes substantially to this hyperthermic response. The systemic administration of α2-adrenergic agonists is known to inhibit both febrile and shivering responses. In the present study, we investigated whether systemic administration of clonidine, a α2-adrenoceptor agonist, attenuates the emotional hyperthermia evoked in conscious unrestrained rats suddenly confronted with a second (intruder) rat, itself confined to a small cage. Pre-implanted thermistors were used to measure BAT and body temperature in conscious, freely moving, male Sprague-Dawley rats. The rats were pre-treated with intraperitoneally administered vehicle (Ringer solution) or clonidine (1, 10 and 100 µg/kg). Clonidine, in a dose-dependent manner, reduced the intruder-elicited increases in BAT (log-dose linear regression F(1,16) = 9.52, R2 = 0.37, P < 0.01) and body temperature (F(1,16) = 6.48, R2 = 0.29, P < 0.05). We also investigated, in anesthetized rats, whether systemic clonidine administration inhibits BAT sympathetic nerve discharge evoked via activation of neurons in the lateral habenula (LHb) - a nucleus involved in the regulation of emotional hyperthermia. In anesthetized rats, clonidine abolished the BAT sympathetic nerve discharges elicited via bicuculline-mediated disinhibition of the LHb. These results suggest that activation of central α2-adrenergic receptors attenuates the process of emotional hyperthermia by reduction of BAT thermogenesis.
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Affiliation(s)
- Anna Antipov
- Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Mariana Brizuela
- Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - William W Blessing
- Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Youichirou Ootsuka
- Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia.
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Sinh V, Ootsuka Y. Blockade of 5-HT2A receptors inhibits emotional hyperthermia in mice. J Physiol Sci 2019; 69:1097-1102. [PMID: 31432430 PMCID: PMC10717664 DOI: 10.1007/s12576-019-00703-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 08/09/2019] [Indexed: 01/20/2023]
Abstract
This study determined whether blockade of 5-hydroxytryptamine 2A (5-HT2A) receptors attenuated hyperthermia and tachycardia responses to psychological stress in mice. For this purpose, male mice (C57BL/6N) were pre-instrumented with a telemetric probe to measure core body temperature and heart rate prior to experimentation. Vehicle or 5-HT2A antagonist, eplivanserin hemifumarate (SR-46349B) ((1Z,2E)-1-(2-fluorophenyl)-3-(4-hydroxyphenyl)-2-propen-1-one O-[2-(dimethylamino) ethyl] oxime hemifumarate) (0.5, 1.0, 5.0 mg/kg), was injected intraperitoneally. To elicit psychological stress, an intruder male mouse confined to a small cage was introduced into the resident mouse's cage 30 min after administration of the injection. The application of this psychological stress increased body temperature by ~ 1.0 °C and heart rate by ~ 150 bpm in the vehicle group. In contrast, SR-46349B was shown to reduce this psychological stress-induced increase in body temperature in a dose-dependent manner (P < 0.05). However, the SR-46349B treatment groups had no influence on the intruder-elicited increase in heart rate. This study, therefore, suggests that 5-HT2A receptors play a significant role in mediating hyperthermia, but not tachycardia, during intruder-elicited psychological stress.
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Affiliation(s)
- Vanshika Sinh
- Centre for Neuroscience, College of Medicine and Public Health, Flinders University, GPO Box 2100, Adelaide, SA, 5001, Australia
| | - Youichirou Ootsuka
- Centre for Neuroscience, College of Medicine and Public Health, Flinders University, GPO Box 2100, Adelaide, SA, 5001, Australia.
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Goh GH, Maloney SK, Mark PJ, Blache D. Episodic Ultradian Events-Ultradian Rhythms. BIOLOGY 2019; 8:biology8010015. [PMID: 30875767 PMCID: PMC6466064 DOI: 10.3390/biology8010015] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/24/2019] [Accepted: 03/09/2019] [Indexed: 11/16/2022]
Abstract
In the fast lane of chronobiology, ultradian events are short-term rhythms that have been observed since the beginning of modern biology and were quantified about a century ago. They are ubiquitous in all biological systems and found in all organisms, from unicellular organisms to mammals, and from single cells to complex biological functions in multicellular animals. Since these events are aperiodic and last for a few minutes to a few hours, they are better classified as episodic ultradian events (EUEs). Their origin is unclear. However, they could have a molecular basis and could be controlled by hormonal inputs-in vertebrates, they originate from the activity of the central nervous system. EUEs are receiving increasing attention but their aperiodic nature requires specific sampling and analytic tools. While longer scale rhythms are adaptations to predictable changes in the environment, in theory, EUEs could contribute to adaptation by preparing organisms and biological functions for unpredictability.
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Affiliation(s)
- Grace H Goh
- School of Human Sciences, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
| | - Shane K Maloney
- School of Human Sciences, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
| | - Peter J Mark
- School of Human Sciences, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
| | - Dominique Blache
- School of Agriculture and Environment and UWA Institute of Agriculture, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
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Grant AD, Wilsterman K, Smarr BL, Kriegsfeld LJ. Evidence for a Coupled Oscillator Model of Endocrine Ultradian Rhythms. J Biol Rhythms 2018; 33:475-496. [PMID: 30132387 DOI: 10.1177/0748730418791423] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Whereas long-period temporal structures in endocrine dynamics have been well studied, endocrine rhythms on the scale of hours are relatively unexplored. The study of these ultradian rhythms (URs) has remained nascent, in part, because a theoretical framework unifying ultradian patterns across systems has not been established. The present overview proposes a conceptual coupled oscillator network model of URs in which oscillating hormonal outputs, or nodes, are connected by edges representing the strength of node-node coupling. We propose that variable-strength coupling exists both within and across classic hormonal axes. Because coupled oscillators synchronize, such a model implies that changes across hormonal systems could be inferred by surveying accessible nodes in the network. This implication would at once simplify the study of URs and open new avenues of exploration into conditions affecting coupling. In support of this proposed framework, we review mammalian evidence for (1) URs of the gut-brain axis and the hypothalamo-pituitary-thyroid, -adrenal, and -gonadal axes, (2) UR coupling within and across these axes; and (3) the relation of these URs to body temperature. URs across these systems exhibit behavior broadly consistent with a coupled oscillator network, maintaining both consistent URs and coupling within and across axes. This model may aid the exploration of mammalian physiology at high temporal resolution and improve the understanding of endocrine system dynamics within individuals.
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Affiliation(s)
- Azure D Grant
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California
| | - Kathryn Wilsterman
- Department of Integrative Biology, University of California, Berkeley, California
| | - Benjamin L Smarr
- Department of Psychology, University of California, Berkeley, California
| | - Lance J Kriegsfeld
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California.,Department of Psychology, University of California, Berkeley, California
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Tsuneki H, Wada T, Sasaoka T. Chronopathophysiological implications of orexin in sleep disturbances and lifestyle-related disorders. Pharmacol Ther 2018; 186:25-44. [DOI: 10.1016/j.pharmthera.2017.12.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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10
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Involvement of orexin neurons in fasting- and central adenosine-induced hypothermia. Sci Rep 2018; 8:2717. [PMID: 29426934 PMCID: PMC5807529 DOI: 10.1038/s41598-018-21252-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 01/31/2018] [Indexed: 01/04/2023] Open
Abstract
We examined whether orexin neurons might play a protective role against fasting- and adenosine-induced hypothermia. We first measured body temperature (BT) in orexin neuron-ablated (ORX-AB) mice and wild-type (WT) controls during 24 hours of fasting. As expected, the magnitude of BT drop and the length of time suffering from hypothermia were greater in ORX-AB mice than in WT mice. Orexin neurons were active just before onset of hypothermia and during the recovery period as revealed by calcium imaging in vivo using G-CaMP. We next examined adenosine-induced hypothermia via an intracerebroventricular administration of an adenosine A1 receptor agonist, N6-cyclohexyladenosine (CHA), which induced hypothermia in both ORX-AB and WT mice. The dose of CHA required to initiate a hypothermic response in ORX-AB mice was more than 10 times larger than the dose for WT mice. Once hypothermia was established, the recovery was seemingly slower in ORX-AB mice. Activation of orexin neurons during the recovery phase was confirmed by immunohistochemistry for c-Fos. We propose that orexin neurons play dual roles (enhancer in the induction phase and compensator during the recovery phase) in adenosine-induced hypothermia and a protective/compensatory role in fasting-induced hypothermia.
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Bourguignon C, Storch KF. Control of Rest:Activity by a Dopaminergic Ultradian Oscillator and the Circadian Clock. Front Neurol 2017; 8:614. [PMID: 29230188 PMCID: PMC5711773 DOI: 10.3389/fneur.2017.00614] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 11/03/2017] [Indexed: 11/23/2022] Open
Abstract
There is long-standing evidence for rhythms in locomotor activity, as well as various other aspects of physiology, with periods substantially shorter than 24 h in organisms ranging from fruit flies to humans. These ultradian oscillations, whose periods frequently fall between 2 and 6 h, are normally well integrated with circadian rhythms; however, they often lack the period stability and expression robustness of the latter. An adaptive advantage of ultradian rhythms has been clearly demonstrated for the common vole, suggesting that they may have evolved to confer social synchrony. The cellular substrate and mechanism of ultradian rhythm generation have remained elusive so far, however recent findings—the subject of this review—now indicate that ultradian locomotor rhythms rely on an oscillator based on dopamine, dubbed the dopaminergic ultradian oscillator (DUO). These findings also reveal that the DUO period can be lengthened from <4 to >48 h by methamphetamine treatment, suggesting that the previously described methamphetamine-sensitive (circadian) oscillator represents a long-period manifestation of the DUO.
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Affiliation(s)
- Clément Bourguignon
- Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada.,Douglas Mental Health University Institute, Montreal, QC, Canada
| | - Kai-Florian Storch
- Douglas Mental Health University Institute, Montreal, QC, Canada.,Department of Psychiatry, McGill University, Montreal, QC, Canada
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Meyer CW, Ootsuka Y, Romanovsky AA. Body Temperature Measurements for Metabolic Phenotyping in Mice. Front Physiol 2017; 8:520. [PMID: 28824441 PMCID: PMC5534453 DOI: 10.3389/fphys.2017.00520] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Accepted: 07/06/2017] [Indexed: 01/01/2023] Open
Abstract
Key Points Rectal probing is subject to procedural bias. This method is suitable for first-line phenotyping, provided probe depth and measurement duration are standardized. It is also useful for detecting individuals with out-of-range body temperatures (during hypothermia, torpor).The colonic temperature attained by inserting the probe >2 cm deep is a measure of deep (core) body temperature.IR imaging of the skin is useful for detecting heat leaks and autonomous thermoregulatory alterations, but it does not measure body temperature.Temperature of the hairy or shaved skin covering the inter-scapular brown adipose tissue can be used as a measure of BAT thermogenesis. However, obtaining such measurements of sufficient quality is very difficult, and interpreting them can be tricky. Temperature differences between the inter-scapular and lumbar areas can be a better measure of the thermogenic activity of inter-scapular brown adipose tissue.Implanted probes for precise determination of BAT temperature (changes) should be fixed close to the Sulzer's vein. For measurement of BAT thermogenesis, core body temperature and BAT temperature should be recorded simultaneously.Tail temperature is suitable to compare the presence or absence of vasoconstriction or vasodilation.Continuous, longitudinal monitoring of core body temperature is preferred over single probing, as the readings are taken in a non-invasive, physiological context.Combining core body temperature measurements with metabolic rate measurements yields insights into the interplay between heat production and heat loss (thermal conductance), potentially revealing novel thermoregulatory phenotypes. Endothermic organisms rely on tightly balanced energy budgets to maintain a regulated body temperature and body mass. Metabolic phenotyping of mice, therefore, often includes the recording of body temperature. Thermometry in mice is conducted at various sites, using various devices and measurement practices, ranging from single-time probing to continuous temperature imaging. Whilst there is broad agreement that body temperature data is of value, procedural considerations of body temperature measurements in the context of metabolic phenotyping are missing. Here, we provide an overview of the various methods currently available for gathering body temperature data from mice. We explore the scope and limitations of thermometry in mice, with the hope of assisting researchers in the selection of appropriate approaches, and conditions, for comprehensive mouse phenotypic analyses.
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Affiliation(s)
- Carola W Meyer
- Department of Pharmacology, Max-Planck Institute for Heart and Lung ResearchBad Nauheim, Germany
| | - Youichirou Ootsuka
- Centre for Neuroscience, School of Medicine, Flinders University of South AustraliaAdelaide, SA, Australia
| | - Andrej A Romanovsky
- FeverLab, St. Joseph's Hospital and Medical CenterPhoenix, AZ, United States
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