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McDonough W, Rich J, Aragon IV, Abou Saleh L, Boyd A, Richter A, Koloteva A, Richter W. Inhibition of type 4 cAMP-phosphodiesterases (PDE4s) in mice induces hypothermia via effects on behavioral and central autonomous thermoregulation. Biochem Pharmacol 2020; 180:114158. [PMID: 32702371 PMCID: PMC7606724 DOI: 10.1016/j.bcp.2020.114158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/16/2020] [Accepted: 07/16/2020] [Indexed: 02/07/2023]
Abstract
Inhibitors of Type 4 cAMP-phosphodiesterases (PDE4s) exert a number of promising therapeutic benefits, including potent anti-inflammatory, memory- and cognition-enhancing, metabolic, and antineoplastic effects. We report here that treatment with a number of distinct PDE4 inhibitors, including Rolipram, Piclamilast, Roflumilast and RS25344, but not treatment with the PDE3-selective inhibitor Cilostamide, induces a rapid (10-30 min), substantial (-5 °C) and long-lasting (up to 5 h) decrease in core body temperature of C57BL/6 mice; thus, identifying a critical role of PDE4 also in the regulation of body temperature. As little as 0.04 mg/kg of the archetypal PDE4 inhibitor Rolipram induces hypothermia. As similar or higher doses of Rolipram were used in a majority of published animal studies, most of the reported findings are likely paralleled by, or potentially impacted by hypothermia induced by these drugs. We further show that PDE4 inhibition affects central body temperature regulation and acts by lowering the cold-defense balance point of behavioral (including posture and locomotion) and autonomous (including cutaneous tail vasodilation) cold-defense mechanisms. In line with the idea of an effect on central body temperature regulation, hypothermia is induced by moderate doses of various brain-penetrant PDE4 inhibitors, but not by similar doses of YM976, a PDE4 inhibitor that does not efficiently cross the blood-brain barrier. Finally, to begin delineating the mechanism of drug-induced hypothermia, we show that blockade of D2/3-type dopaminergic, but not β-adrenergic, H1-histaminergic or opiate receptors, can alleviate PDE4 inhibitor-induced hypothermia. We thus propose that increased D2/3-type dopaminergic signaling, triggered by PDE4 inhibitor-induced and cAMP-mediated dopamine release in the thermoregulatory centers of the hypothalamus, is a significant contributor to PDE4 inhibitor-induced hypothermia.
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Affiliation(s)
- Will McDonough
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Justin Rich
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Ileana V Aragon
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Lina Abou Saleh
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Abigail Boyd
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Aris Richter
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Anna Koloteva
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States
| | - Wito Richter
- Department of Biochemistry & Molecular Biology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, United States.
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Zaretsky DV, Romanovsky AA, Zaretskaia MV, Molkov YI. Tissue oxidative metabolism can increase the difference between local temperature and arterial blood temperature by up to 1.3 oC: Implications for brain, brown adipose tissue, and muscle physiology. Temperature (Austin) 2018; 5:22-35. [PMID: 29687042 DOI: 10.1080/23328940.2018.1437311] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 02/02/2018] [Accepted: 02/02/2018] [Indexed: 10/18/2022] Open
Abstract
Tissue temperature increases, when oxidative metabolism is boosted. The source of nutrients and oxygen for this metabolism is the blood. The blood also cools down the tissue, and this is the only cooling mechanism, when direct dissipation of heat from the tissue to the environment is insignificant, e.g., in the brain. While this concept is relatively simple, it has not been described quantitatively. The purpose of the present work was to answer two questions: 1) to what extent can oxidative metabolism make the organ tissue warmer than the body core, and, 2) how quickly are changes in the local metabolism reflected in the temperature of the tissue? Our theoretical analysis demonstrates that, at equilibrium, given that heat exchange with the organ is provided by the blood, the temperature difference between the organ tissue and the arterial blood is proportional to the arteriovenous difference in oxygen content, does not depend on the blood flow, and cannot exceed 1.3oC. Unlike the equilibrium temperature difference, the rate of change of the local temperature, with respect to time, does depend on the blood flow. In organs with high perfusion rates, such as the brain and muscles, temperature changes occur on a time scale of a few minutes. In organs with low perfusion rates, such changes may have characteristic time constants of tens or hundreds of minutes. Our analysis explains, why arterial blood temperature is the main determinant of the temperature of tissues with limited heat exchange, such as the brain.
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Affiliation(s)
- Dmitry V Zaretsky
- Discovery and Translational Medicine Division, Intarcia Therapeutics, Research Triangle, NC 27709
| | - Andrej A Romanovsky
- Systemic Inflammation Laboratory (FeverLab), Trauma Research, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013
| | - Maria V Zaretskaia
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Yaroslav I Molkov
- Department of Mathematics and Statistics and Neuroscience Institute, Georgia State University, GA 30303
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Zaretsky DV, Kline H, Zaretskaia MV, Brown MB, Durant PJ, Alves NJ, Rusyniak DE. Disinhibiting neurons in the dorsomedial hypothalamus delays the onset of exertional fatigue and exhaustion in rats exercising in a warm environment. Brain Res 2018; 1689:12-20. [PMID: 29577887 DOI: 10.1016/j.brainres.2018.03.026] [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] [Received: 11/08/2017] [Revised: 03/19/2018] [Accepted: 03/20/2018] [Indexed: 12/31/2022]
Abstract
Stimulants cause hyperthermia, in part, by increasing heat generation through exercise. Stimulants also delay the onset of fatigue and exhaustion allowing animals to exercise longer. If used in a warm environment, this combination (increased exercise and decreased fatigue) can cause heat stroke. The dorsomedial hypothalamus (DMH) is involved in mediating locomotion from stimulants. Furthermore, inhibiting the DMH decreases locomotion and prevents hyperthermia in rats given stimulants in a warm environment. Whether the DMH is involved in mediating exercise-induced fatigue and exhaustion is not known. We hypothesized that disinhibiting neurons in the dorsomedial hypothalamus (DMH) would delay the onset of fatigue and exhaustion in animals exercising in a warm environment. To test this hypothesis, we used automated video tracking software to measure fatigue and exhaustion. In rats, using wearable mini-pumps, we demonstrated that disinhibiting the DMH, via bicuculline perfusion (5 µM), increased the duration of exercise in a warm environment as compared to control animals (25 ± 3 min vs 15 ± 2 min). Bicuculline-perfused animals also had higher temperatures at exhaustion (41.4 ± 0.2 °C vs 40.0 ± 0.4 °C). Disinhibiting neurons in the DMH also increased the time to fatigue. Our data show that the same region of the hypothalamus that is involved in mediating locomotion to stimulants, is also involved in controlling exhaustion and fatigue. These findings have implications for understanding the cause and treatment of stimulant-induced-hyperthermia.
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Affiliation(s)
- Dmitry V Zaretsky
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Hannah Kline
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Maria V Zaretskaia
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Mary Beth Brown
- Department of Physical Therapy, Indiana University School of Health and Rehabilitation Sciences, USA
| | - Pamela J Durant
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Nathan J Alves
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daniel E Rusyniak
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA.
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Zaretsky DV, Zaretskaia MV, Durant PJ, Rusyniak DE. Treadmill running restores MDMA-mediated hyperthermia prevented by inhibition of the dorsomedial hypothalamus. Brain Res 2015; 1608:75-81. [PMID: 25725382 DOI: 10.1016/j.brainres.2015.02.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 02/16/2015] [Accepted: 02/17/2015] [Indexed: 02/08/2023]
Abstract
The contribution of exercise to hyperthermia mediated by MDMA is not known. We recently showed that inhibiting the dorsomedial hypothalamus (DMH) attenuated spontaneous locomotion and hyperthermia and prevented deaths in rats given MDMA in a warm environment. The goal of this study was to confirm that restoring locomotion through a treadmill would reverse these effects thereby confirming that locomotion mediated by the DMH contributes to MDMA-mediated hyperthermia. Rats were randomized to receive bilateral microinjections, into the region of the DMH, of muscimol (80pmol/100nl) or artificial CSF followed by a systemic dose of either MDMA (7.5mg/kg, i.v.) or saline. Immediately after the systemic injection, rats were placed on a motorized treadmill maintained at 32°C. Rats were exercised at a fixed speed (10m/min) until their core temperature reached 41°C. Our results showed that a fixed exercise load abolished the decreases in temperature and mortality, seen previously with inhibition of the DMH in freely moving rats. Therefore, locomotion mediated by neurons in the DMH is critical to the development of hyperthermia from MDMA.
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Affiliation(s)
- Dmitry V Zaretsky
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Maria V Zaretskaia
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Pamela J Durant
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daniel E Rusyniak
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA.
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Kiyatkin EA, Ren S. Clubbing with ecstasy. Temperature (Austin) 2014; 1:160-1. [PMID: 27627800 PMCID: PMC5008718 DOI: 10.4161/23328940.2014.980137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 10/20/2014] [Accepted: 10/20/2014] [Indexed: 01/10/2023] Open
Abstract
In this issue, Parrot and Young present the results of temperature measurements in young individuals “partying” with 3,4-methylenedioxymethamphetamine (MDMA or Ecstasy). This editorial commentary briefly summarizes the main findings of their study, provides background gained from previous animal experiments, and reviews the implications for the development of future pharmacotherapies and harm reduction strategies.
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Affiliation(s)
- Eugene A Kiyatkin
- In-Vivo Electrophysiology Unit; Behavioral Neuroscience Branch; National Institute on Drug Abuse - Intramural Research Program; National Institutes of Health; DHHS ; Baltimore, MD USA
| | - Suelynn Ren
- In-Vivo Electrophysiology Unit; Behavioral Neuroscience Branch; National Institute on Drug Abuse - Intramural Research Program; National Institutes of Health; DHHS ; Baltimore, MD USA
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Abstract
Amphetamine (Amp) increases exercise duration. It is thought to do so by masking fatigue, but there have been very few studies looking at the effect of amphetamine on maximal oxygen consumption (VO2MAX) and running economy. Furthermore, it is unknown if amphetamine's effect on exercise duration occurs in a warm environment. We conducted separate experiments in male Sprague-Dawley rats testing the effect of amphetamine on VO2MAX (n = 12), running economy (n = 12), and exercise duration (n = 24) in a warm environment. For VO2MAX and running economy, rats were randomized to either amphetamine at 1 mg/kg (Amp-1) or 2 mg/kg (Amp-2). Animals served as their own controls in a crossover design with the administration order counter-balanced. To study the effect of amphetamine on exercise duration, we conducted run-to-exhaustion treadmill testing on rats in a 32˚C environment following administration of Amp-1, Amp-2, or Saline. Compared to control, Amp-2 increased VO2MAX (by 861 ± 184 ml/kg/hr, p = 0.005) and the time to VO2MAX (by 2.5 ± 0.8 min, p = 0.03). Amp-1 had no effect on VO2MAX but increased the time to VO2MAX (by 1.7 ± 0.5 min, p = 0.03). Neither dose improved running economy. In the warm, only rats in the Amp-1 group (+9.4 min, p = 0.02) had an increased time to exhaustion. Compared to control (41.6 ± 0.3°C), both amphetamine doses had higher temperatures at exhaustion: Amp-1 (42.0 ± 0.2°C) and Amp-2 (42.1 ± 0.2°C). Our results suggest that ergogenic effect of amphetamine occurs by masking fatigue but this effect may be offset in the warm with higher doses.
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Affiliation(s)
- Dmitry V Zaretsky
- Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202
| | - Mary Beth Brown
- Department of Physical Therapy, Indiana University School of Health and Rehabilitation Sciences, 1140 W Michigan St, Indianapolis, Indiana, USA, 46202
| | - Maria V Zaretskaia
- Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202
| | - Pamela J Durant
- Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202
| | - Daniel E Rusyniak
- Department of Emergency Medicine, Indiana University School of Medicine, 720 Eskenazi Ave, Indianapolis, Indiana, USA, 46202; Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barhill Drive, Indianapolis, Indiana, USA, 46202
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