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Crew RC, Waddell BJ, Maloney SK, Mark PJ. Diet-induced obesity reduces core body temperature across the estrous cycle and pregnancy in the rat. Chronobiol Int 2018; 35:1077-1087. [PMID: 29659304 DOI: 10.1080/07420528.2018.1458035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Obesity during pregnancy causes adverse maternal and fetal health outcomes and programs offspring for adult-onset diseases, including cardiovascular disease. Obesity also disrupts core body temperature (Tc) regulation in nonpregnant rodents; however, it is unknown whether obesity alters normal maternal Tc adaptations to pregnancy. Since Tc is influenced by the circadian system, and both obesity and pregnancy alter circadian biology, it was hypothesized that obesity disrupts the normal rhythmic patterns of Tc before and during gestation. Obesity was induced by cafeteria (CAF) feeding in female Wistar rats for 8 weeks prior to and during gestation, whereas control (CON) animals had free access to chow. Intraperitoneal temperature loggers measured daily Tc profiles throughout the study, while maternal body composition and leptin levels were assessed near term. Daily temperature profiles were examined for rhythmic features (mesor, amplitude and acrophase) by cosine regression analysis. CAF animals exhibited increased fat mass (93%) and associated hyperleptinemia (3.2-fold increase) compared to CON animals. CAF consumption reduced the average Tc (by up to 0.29°C) across the estrous cycle and most of pregnancy; however, Tc for CAF and CON animals converged toward the end of gestation. Obesity reduced the amplitude of Tc rhythms at estrus and proestrus and on day 8 of pregnancy, but increased the amplitude at day 20 of pregnancy. Photoperiod analysis revealed that obesity reduced Tc exclusively in the light period during pre-pregnancy but only during the dark period in late gestation. In conclusion, obesity alters rhythmic Tc profiles and reduces the magnitude of the Tc decline late in rat gestation, which may have implications for maternal health and fetal development.
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Affiliation(s)
- Rachael C Crew
- a School of Human Sciences , The University of Western Australia , Perth , Australia
| | - Brendan J Waddell
- a School of Human Sciences , The University of Western Australia , Perth , Australia
| | - Shane K Maloney
- a School of Human Sciences , The University of Western Australia , Perth , Australia
| | - Peter J Mark
- a School of Human Sciences , The University of Western Australia , Perth , Australia
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Trethowan PD, Hart T, Loveridge AJ, Haw A, Fuller A, Macdonald DW. Improved homeothermy and hypothermia in African lions during gestation. Biol Lett 2017; 12:rsbl.2016.0645. [PMID: 27881765 DOI: 10.1098/rsbl.2016.0645] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/27/2016] [Indexed: 01/06/2023] Open
Abstract
Mammals use endogenously produced heat to maintain a high and relatively constant core body temperature (Tb). How they regulate their Tb during reproduction might inform us as to what thermal conditions are necessary for optimal development of offspring. However, few studies have measured Tb in free-ranging animals for sufficient periods of time to encounter reproductive events. We measured Tb continuously in six free-ranging adult female African lions (Panthera leo) for approximately 1 year. Lions reduced the 24 h amplitude of Tb by about 25% during gestation and decreased mean 24 h Tb by 1.3 ± 0.1°C over the course of the gestation, reducing incidences of hyperthermia (Tb > 39.5°C). The observation of improved homeothermy during reproduction may support the parental care model (PCM) for the evolution of endothermy, which postulates that endothermy arose in birds and mammals as a consequence of more general selection for parental care. According to the PCM, endothermy arose because it enabled parents to better control incubation temperature, leading to rapid growth and development of offspring and thus to fitness benefits for the parents. Whether the precision of Tb regulation in pregnant lions, and consequently their reproductive success, will be influenced by changing environmental conditions, particularly hotter and drier periods associated with climate change, remains to be determined.
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Affiliation(s)
- Paul D Trethowan
- Wildlife Conservation Research Unit, The Recanati-Kaplan Centre, Department of Zoology, University of Oxford, Oxford, UK
| | - Tom Hart
- Ocean Research and Conservation Group, Department of Zoology, University of Oxford, Oxford, UK
| | - Andrew J Loveridge
- Wildlife Conservation Research Unit, The Recanati-Kaplan Centre, Department of Zoology, University of Oxford, Oxford, UK
| | - Anna Haw
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - David W Macdonald
- Wildlife Conservation Research Unit, The Recanati-Kaplan Centre, Department of Zoology, University of Oxford, Oxford, UK
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Abstract
In mammals and birds, all oxygen used (VO2) must pass through the lungs; hence, some degree of coupling between VO2 and pulmonary ventilation (VE) is highly predictable. Nevertheless, VE is also involved with CO2 elimination, a task that is often in conflict with the convection of O2. In hot or cold conditions, the relationship between VE and VO2 includes the participation of the respiratory apparatus to the control of body temperature and water balance. Some compromise among these tasks is achieved through changes in breathing pattern, uncoupling changes in alveolar ventilation from VE. This article examines primarily the relationship between VE and VO2 under thermal stimuli. In the process, it considers how the relationship is influenced by hypoxia, hypercapnia or changes in metabolic level. The shuffling of tasks in emergency situations illustrates that the constraints on VE-VO2 for the protection of blood gases have ample room for flexibility. However, when other priorities do not interfere with the primary goal of gas exchange, VE follows metabolic rate quite closely. The fact that arterial CO2 remains stable when metabolism is changed by the most diverse circumstances (moderate exercise, cold, cold and exercise combined, variations in body size, caloric intake, age, time of the day, hormones, drugs, etc.) makes it unlikely that VE and metabolism are controlled in parallel by the condition responsible for the metabolic change. Rather, some observations support the view that the gaseous component of metabolic rate, probably CO2, may provide the link between the metabolic level and VE.
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Endogenous angiotensin II and the regulation of oxygen consumption and colonic temperature in rats. J Therm Biol 2012. [DOI: 10.1016/j.jtherbio.2011.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Hahn JD, Swanson LW. Distinct patterns of neuronal inputs and outputs of the juxtaparaventricular and suprafornical regions of the lateral hypothalamic area in the male rat. ACTA ACUST UNITED AC 2010; 64:14-103. [PMID: 20170674 DOI: 10.1016/j.brainresrev.2010.02.002] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 02/09/2010] [Accepted: 02/10/2010] [Indexed: 12/26/2022]
Abstract
We have analyzed at high resolution the neuroanatomical connections of the juxtaparaventricular region of the lateral hypothalamic area (LHAjp); as a control and in comparison to this, we also performed a preliminary analysis of a nearby LHA region that is dorsal to the fornix, namely the LHA suprafornical region (LHAs). The connections of these LHA regions were revealed with a coinjection tract-tracing technique involving a retrograde (cholera toxin B subunit) and anterograde (Phaseolus vulgaris leucoagglutinin) tracer. The LHAjp and LHAs together connect with almost every major division of the cerebrum and cerebrospinal trunk, but their connection profiles are markedly different and distinct. In simple terms, the connections of the LHAjp indicate a possible primary role in the modulation of defensive behavior; for the LHAs, a role in the modulation of ingestive behavior is suggested. However, the relation of the LHAjp and LHAs to potential modulation of these behaviors, as indicated by their neuroanatomical connections, appears to be highly integrative as it includes each of the major functional divisions of the nervous system that together determine behavior, i.e., cognitive, state, sensory, and motor. Furthermore, although a primary role is indicated for each region with respect to a particular mode of behavior, intermode modulation of behavior is also indicated. In summary, the extrinsic connections of the LHAjp and LHAs (so far as we have described them) suggest that these regions have a profoundly integrative role in which they may participate in the orchestrated modulation of elaborate behavioral repertoires.
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Affiliation(s)
- Joel D Hahn
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2520, USA.
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Begg DP, Mathai ML, McKinley MJ, Frappell PB, Kent S. Central nitric oxide synthase inhibition restores behaviorally mediated lipopolysaccharide induced fever in near-term rats. Physiol Behav 2008; 94:630-4. [DOI: 10.1016/j.physbeh.2008.03.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2007] [Revised: 03/28/2008] [Accepted: 03/31/2008] [Indexed: 01/22/2023]
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Leite LHR, Lacerda ACR, Marubayashi U, Coimbra CC. Central angiotensin AT1-receptor blockade affects thermoregulation and running performance in rats. Am J Physiol Regul Integr Comp Physiol 2006; 291:R603-7. [PMID: 16614062 DOI: 10.1152/ajpregu.00038.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of central angiotensin AT1-receptor blockade on thermoregulation in rats during exercise on a treadmill (18 m/min, 5% inclination) was investigated. Core (Tb) and skin tail temperatures were measured in rats while they were exercising until fatigue after injection of 2 microl of losartan (Los; 20 nmol, n = 4; 30 nmol, n = 4; 60 nmol, n = 7), an angiotensin II AT1-receptor antagonist, or 2 microl of 0.15 mol/l NaCl (Sal; n = 15) into the right lateral cerebral ventricle. Body heat rate (BHR), heat storage rate, threshold Tb for tail vasodilation (TTbV), time to fatigue, and workload were calculated. During exercise, the BHR and heat storage rate of Los-treated animals were, respectively, 40 and 53% higher (P < 0.01) than in Sal-treated animals. Additionally, rats injected with Los showed an increased TTbV (38.59 +/- 0.19 degrees C for Los vs. 38.12 +/- 0.1 degrees C for Sal, P < 0.02), a higher Tb at fatigue point (39.07 +/- 0.14 degrees C Los vs. 38.66 +/- 0.07 degrees C Sal, P < 0.01), and a reduced running performance (27.29 +/- 4.48 min Los vs. 52.47 +/- 6.67 min Sal, P < 0.01), which was closely related to the increased BHR. Our data suggest that AT1-receptor blockade attenuates heat dissipation during exercise due to the higher TTbV, leading to a faster exercise-induced increase in Tb, thus decreasing running performance.
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Affiliation(s)
- Laura H R Leite
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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Abstract
Pregnant rats in late gestation show a reduced fever response after stimulation with lipopolysaccharide (LPS). This can result from either an increased action of endogenous antipyretics or a reduction in the production or action of endogenous pyrogens. Nonpregnant rats given LPS release interleukin (IL)-6, which causes nuclear translocation of the signal transducer and activator of transcription 3 (STAT3) in the vascular organ of the lamina terminalis (OVLT), followed by a significant increase in core body temperature. The present study investigated whether the reduced fever response in near-term pregnant rats is associated with a reduced nuclear STAT3 response. Rats at gestation day 15 (G15), gestation day 21 (G21, near term) and at lactation day 5 (L5) were injected with LPS (50 microg/kg, i.p.) or vehicle. Only near-term pregnant rats responded with an attenuated body temperature during the fever response. Immunohistological analysis indicated no significant difference in nuclear STAT3 in the OVLT of the different animal groups 2 h after LPS. Measurement of total and phosphorylated STAT3 protein in the OVLT with semiquantitative western blot revealed no significant differences of this protein among these immune challenged animal groups. IL-6 concentrations were also similar at G15, G21 and L5 2 h after injection of LPS. These results lead to the conclusion that the attenuation of the fever response at near-term pregnancy is not associated with a reduced amount of nuclear STAT3 in the OVLT, indicating a maintained IL-6-STAT3 signalling pathway in the OVLT.
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Affiliation(s)
- E-M Harré
- Hotchkiss Brain Institute, Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.
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