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Kozyreva TV, Orlov IV, Boyarskaya AR, Voronova IP. Hypothalamic TRPM8 and TRPA1 ion channel genes in the regulation of temperature homeostasis at water balance changes. Neurosci Lett 2024; 828:137763. [PMID: 38574849 DOI: 10.1016/j.neulet.2024.137763] [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: 02/06/2024] [Revised: 03/28/2024] [Accepted: 03/29/2024] [Indexed: 04/06/2024]
Abstract
The role of the hypothalamic cold-sensitive ion channels - transient receptor potential melastatin 8 (TRPM8) and transient receptor potential ankyrin 1 (TRPA1) in homeostatic systems of thermoregulation and water-salt balance - is not clear. The interaction of homeostatic systems of thermoregulation and water-salt balance without additional temperature load did not receive due attention, too. On the models of water-balance disturbance, we tried to elucidate some aspect of these problems. Body temperature (Tbody), O2 consumption, CO2 excretion, electrical muscle activity (EMA), temperature of tail skin (Ttail), plasma osmolality, as well as gene expression of hypothalamic TRPM8 and TRPA1 have been registered in rats of 3 groups: control; water-deprived (3 days under dry-eating); and hyperhydrated (6 days without dry food, drinking liquid 4 % sucrose). No relationship was observed between plasma osmolality and gene expression of Trpm8 and Trpa1. In water-deprived rats, the constriction of skin vessels, increased fat metabolism by 10 % and increased EMA by 48 % allowed the animals to maintain Tbody unchanged. The hyperhydrated rats did not develop sufficient mechanisms, and their Tbody decreased by 0.8 °C. The development of reactions was correlated with the expression of genes of thermosensitive ion channels in the anterior hypothalamus. Ttail had a direct correlation with the expression of the Trpm8 gene, whereas EMA directly correlated with the expression of the Trpa1 gene in water-deprived group. The obtained data attract attention from the point of view of management and correction of physiological functions by modulating the ion channel gene expression.
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Affiliation(s)
- T V Kozyreva
- Institute of Neuroscience and Medicine, Timakov str. 4, Novosibirsk 630117, Russia; Novosibirsk State University, Pirogov str. 2, Novosibirsk 630090, Russia.
| | - I V Orlov
- Institute of Neuroscience and Medicine, Timakov str. 4, Novosibirsk 630117, Russia; Novosibirsk State University, Pirogov str. 2, Novosibirsk 630090, Russia.
| | - A R Boyarskaya
- Institute of Neuroscience and Medicine, Timakov str. 4, Novosibirsk 630117, Russia.
| | - I P Voronova
- Institute of Neuroscience and Medicine, Timakov str. 4, Novosibirsk 630117, Russia.
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2
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Santiago HP, Leite LHR, Lima PMA, Fóscolo DRC, Natali AJ, Prímola-Gomes TN, Szawka RE, Coimbra CC. Effects of physical training on hypothalamic neuronal activation and expressions of vasopressin and oxytocin in SHR after running until fatigue. Pflugers Arch 2024; 476:365-377. [PMID: 38308122 DOI: 10.1007/s00424-024-02916-1] [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: 11/14/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/04/2024]
Abstract
To assess the influence of physical training on neuronal activation and hypothalamic expression of vasopressin and oxytocin in spontaneously hypertensive rats (SHR), untrained and trained normotensive rats and SHR were submitted to running until fatigue while internal body and tail temperatures were recorded. Hypothalamic c-Fos expression was evaluated in thermoregulatory centers such as the median preoptic nucleus (MnPO), medial preoptic nucleus (mPOA), paraventricular nucleus of the hypothalamus (PVN), and supraoptic nucleus (SON). The PVN and the SON were also investigated for vasopressin and oxytocin expressions. Although exercise training improved the workload performed by the animals, it was reduced in SHR and followed by increased internal body temperature due to tail vasodilation deficit. Physical training enhanced c-Fos expression in the MnPO, mPOA, and PVN of both strains, and these responses were attenuated in SHR. Vasopressin immunoreactivity in the PVN was also increased by physical training to a lesser extent in SHR. The already-reduced oxytocin expression in the PVN of SHR was increased in response to physical training. Within the SON, neuronal activation and the expressions of vasopressin and oxytocin were reduced by hypertension and unaffected by physical training. The data indicate that physical training counterbalances in part the negative effect of hypertension on hypothalamic neuronal activation elicited by exercise, as well as on the expression of vasopressin and oxytocin. These hypertension features seem to negatively influence the workload performed by SHR due to the hyperthermia derived from the inability of physical training to improve heat dissipation through skin vasodilation.
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Affiliation(s)
- Henrique P Santiago
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Laura H R Leite
- Departamento de Biofísica e Fisiologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Paulo M A Lima
- Núcleo de Pesquisa da Faculdade de Medicina da Universidade de Rio Verde, Universidade de Rio Verde, Campus Goiânia, Goiânia, Brazil
| | - Daniela R C Fóscolo
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Antônio José Natali
- Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | | | - Raphael E Szawka
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Cândido C Coimbra
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, 31270-901, Brazil.
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3
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Haan KD, Park SJ, Nakamura Y, Fukami K, Fisher TE. Osmotically evoked PLCδ1-dependent translocation of ΔN-TRPV1 channels in rat supraoptic neurons. iScience 2023; 26:106258. [PMID: 36926650 PMCID: PMC10011827 DOI: 10.1016/j.isci.2023.106258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/10/2022] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Osmoregulation is an essential homeostatic process that requires constant release of vasopressin during sustained increases in plasma osmolality. The magnocellular neurosecretory cells (MNCs) respond to increases in external osmolality through increases in the activity of ΔN-TRPV1 channels, which leads to increased action potential firing and vasopressin release. We show that sustained exposure of acutely isolated rat and mouse MNCs to hypertonic solutions (90 min) causes a reversible translocation of ΔN-TRPV1 channels from internal stores to the plasma membrane that depends on the activation of phospholipase C and on SNARE-dependent exocytosis. ΔN-TRPV1 channel translocation is absent in MNCs isolated from transgenic mice lacking the PLCδ1 isoform, suggesting that PLCδ1 is essential for triggering this process. The translocation of ΔN-TRPV1 channels to the cell surface could contribute to the maintenance of MNC excitability during sustained increases in osmolality. Our data therefore have important implications for the mechanisms underlying mammalian osmoregulation.
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Affiliation(s)
- Kirk D Haan
- Department of Anatomy, Physiology, and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Sung Jin Park
- Department of Anatomy, Physiology, and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Yoshikazu Nakamura
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba, Japan
| | - Kiyoko Fukami
- Laboratory of Genome and Biosignals, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Thomas E Fisher
- Department of Anatomy, Physiology, and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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4
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Sudbury JR, Zaelzer C, Trudel E, Bumagin A, Bourque CW. Synaptic control of rat magnocellular neurosecretory cells by warm-sensing neurons in the organum vasculosum lamina terminalis. J Neuroendocrinol 2022; 34:e13214. [PMID: 36426844 DOI: 10.1111/jne.13214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 10/07/2022] [Accepted: 10/27/2022] [Indexed: 11/11/2022]
Abstract
Increases in core body temperature cause secretion of vasopressin (vasopressin, antidiuretic hormone) to promote water reabsorption and blunt water losses incurred through homeostatic evaporative cooling. Subtypes of transient receptor potential vanilloid (Trpv) channels have been shown to contribute to the intrinsic regulation of vasopressin-releasing magnocellular neurosecretory cells (MNCs) in the supraoptic nucleus (SON) and paraventricular nucleus (PVN). However, MNCs in vivo can also be excited by local heating of the adjacent preoptic area, indicating they receive thermosensory information from other areas. Here, we investigated whether neurons in the organum vasculosum lamina terminalis (OVLT) contribute to this process using in vitro electrophysiological approaches in male rats. We found that the majority of OVLT neurons are thermosensitive in the physiological range (36-39°C) and that this property is retained under conditions blocking synaptic transmission. A subset of these neurons could be antidromically activated by electrical stimulation in the SON. Whole cell recordings from SON MNCs revealed that heating significantly increases the rate of spontaneous excitatory postsynaptic currents (sEPCSs), and that this response is abolished by lesions targeting the OVLT, but not by bilateral lesions placed in the adjacent preoptic area. Finally, local heating of the OVLT caused a significant excitation of MNCs in the absence of temperature changes in the SON, and this effect was blocked by inhibitors of ionotropic glutamate receptors. These findings indicate that the OVLT serves as an important thermosensory nucleus and contributes to the activation of MNCs during physiological heating.
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Affiliation(s)
- Jessica R Sudbury
- Brain Repair and Integrative Neuroscience Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Cristian Zaelzer
- Brain Repair and Integrative Neuroscience Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Eric Trudel
- Brain Repair and Integrative Neuroscience Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Anna Bumagin
- Brain Repair and Integrative Neuroscience Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Charles W Bourque
- Brain Repair and Integrative Neuroscience Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
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5
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Blocking TRPV4 Ameliorates Osteoarthritis by Inhibiting M1 Macrophage Polarization via the ROS/NLRP3 Signaling Pathway. Antioxidants (Basel) 2022; 11:antiox11122315. [PMID: 36552524 PMCID: PMC9774183 DOI: 10.3390/antiox11122315] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/12/2022] [Accepted: 11/21/2022] [Indexed: 11/25/2022] Open
Abstract
Osteoarthritis (OA) is a low-level inflammatory disease in which synovial macrophage M1 polarization exacerbates the progression of synovitis and OA. Notedly, the ROS (reactive oxygen species) level in macrophages is intimately implicated in macrophage M1 polarization. TRPV4 (transient receptor potential channel subfamily V member 4), as an ion channel, plays a pivotal role in oxidative stress and inflammation. In this study, we investigated the role of TRPV4 in OA progression and M1 macrophage polarization. Male adult Sprague-Dawley (SD) rats underwent a medial meniscus radial transection operation to create an OA model in vivo and RAW 264.7 cells were intervened with 100 ng/mL LPS (lipopolysaccharide) to induce M1-polarized macrophages in vitro. We demonstrated that the infiltration of M1 synovial macrophages and the expression of TRPV4 were increased significantly in OA synovium. In addition, intra-articular injection of HC067074 (a specific inhibitor of TRPV4) alleviated the progression of rat OA and significantly decreased synovial macrophage M1 polarization. Further mechanisms suggested that ROS production by M1 macrophages was decreased after TRPV4 inhibition. In addition, NLRP3 (pyrin domain containing protein 3) as a downstream effector of ROS in M1-polarized macrophage, was significantly suppressed following TRPV4 inhibition. In conclusion, this study discovered that inhibition of TRPV4 delays OA progression by inhibiting M1 synovial macrophage polarization through the ROS/NLRP3 pathway.
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Miyata S. Glial functions in the blood-brain communication at the circumventricular organs. Front Neurosci 2022; 16:991779. [PMID: 36278020 PMCID: PMC9583022 DOI: 10.3389/fnins.2022.991779] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
The circumventricular organs (CVOs) are located around the brain ventricles, lack a blood-brain barrier (BBB) and sense blood-derived molecules. This review discusses recent advances in the importance of CVO functions, especially glial cells transferring periphery inflammation signals to the brain. The CVOs show size-limited vascular permeability, allowing the passage of molecules with molecular weight <10,000. This indicates that the lack of an endothelial cell barrier does not mean the free movement of blood-derived molecules into the CVO parenchyma. Astrocytes and tanycytes constitute a dense barrier at the distal CVO subdivision, preventing the free diffusion of blood-derived molecules into neighboring brain regions. Tanycytes in the CVOs mediate communication between cerebrospinal fluid and brain parenchyma via transcytosis. Microglia and macrophages of the CVOs are essential for transmitting peripheral information to other brain regions via toll-like receptor 2 (TLR2). Inhibition of TLR2 signaling or depletion of microglia and macrophages in the brain eliminates TLR2-dependent inflammatory responses. In contrast to TLR2, astrocytes and tanycytes in the CVOs of the brain are crucial for initiating lipopolysaccharide (LPS)-induced inflammatory responses via TLR4. Depletion of microglia and macrophages augments LPS-induced fever and chronic sickness responses. Microglia and macrophages in the CVOs are continuously activated, even under normal physiological conditions, as they exhibit activated morphology and express the M1/M2 marker proteins. Moreover, the microglial proliferation occurs in various regions, such as the hypothalamus, medulla oblongata, and telencephalon, with a marked increase in the CVOs, due to low-dose LPS administration, and after high-dose LPS administration, proliferation is seen in most brain regions, except for the cerebral cortex and hippocampus. A transient increase in the microglial population is beneficial during LPS-induced inflammation for attenuating sickness response. Transient receptor potential receptor vanilloid 1 expressed in astrocytes and tanycytes of the CVOs is responsible for thermoregulation upon exposure to a warm environment less than 37°C. Alternatively, Nax expressed in astrocytes and tanycytes of the CVOs is crucial for maintaining body fluid homeostasis. Thus, recent findings indicate that glial cells in the brain CVOs are essential for initiating neuroinflammatory responses and maintaining body fluid and thermal homeostasis.
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7
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Takakura I, Kishida T, Yokoi R, Souma S. Estradiol dominance induces hemodilution and mild hematological alterations in mifepristone-treated rats. J Toxicol Sci 2022; 47:301-308. [PMID: 35786681 DOI: 10.2131/jts.47.301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We examined that an estradiol-dominant state against progesterone could affect hematological parameters through hemodilution because estradiol is known to increase plasma volume via oncotic pressure. We performed a 2- and 3-week repeated oral dose study with mifepristone, a progesterone receptor antagonist, in female rats and examined erythrocyte counts, hemoglobin, hematocrit, plasma volume, levels of estradiol and progesterone, water intake, and water loss. Mifepristone treatment decreased some hematological parameters mildly and increased plasma volume. There were no remarkable changes in the balance of water intake and water loss through urination. Both estradiol and progesterone levels and the ratio of estradiol to progesterone increased. Therefore, our findings indicate that repeated mifepristone treatment increases estradiol levels and plasma volume, resulting in lower erythrocyte counts, hemoglobin, and hematocrit. The present study proved the possible contribution of estradiol to understanding the toxicological significance of mifepristone-induced hemodilution.
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Affiliation(s)
- Ikuro Takakura
- Safety Research Department, R&D, Kissei Pharmaceuticals Co., Ltd
| | - Tomoyuki Kishida
- Safety Research Department, R&D, Kissei Pharmaceuticals Co., Ltd
| | - Ryohei Yokoi
- Safety Research Department, R&D, Kissei Pharmaceuticals Co., Ltd
| | - Shinji Souma
- Safety Research Department, R&D, Kissei Pharmaceuticals Co., Ltd
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8
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Sheng W, Harden SW, Tan Y, Krause EG, Frazier CJ. Dendritic osmosensors modulate activity-induced calcium influx in oxytocinergic magnocellular neurons of the mouse PVN. eLife 2021; 10:e63486. [PMID: 34250900 PMCID: PMC8457833 DOI: 10.7554/elife.63486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 07/11/2021] [Indexed: 11/13/2022] Open
Abstract
Hypothalamic oxytocinergic magnocellular neurons have a fascinating ability to release peptide from both their axon terminals and from their dendrites. Existing data indicates that the relationship between somatic activity and dendritic release is not constant, but the mechanisms through which this relationship can be modulated are not completely understood. Here, we use a combination of electrical and optical recording techniques to quantify activity-induced calcium influx in proximal vs. distal dendrites of oxytocinergic magnocellular neurons located in the paraventricular nucleus of the hypothalamus (OT-MCNs). Results reveal that the dendrites of OT-MCNs are weak conductors of somatic voltage changes; however, activity-induced dendritic calcium influx can be robustly regulated by both osmosensitive and non-osmosensitive ion channels located along the dendritic membrane. Overall, this study reveals that dendritic conductivity is a dynamic and endogenously regulated feature of OT-MCNs that is likely to have substantial functional impact on central oxytocin release.
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Affiliation(s)
- Wanhui Sheng
- Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesvilleUnited States
| | - Scott W Harden
- Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesvilleUnited States
| | - Yalun Tan
- Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesvilleUnited States
- Department of Anesthesiology, School of Medicine, Stanford UniversityStanfordUnited States
| | - Eric G Krause
- Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesvilleUnited States
- Center for Integrative Cardiovascular and Metabolic Diseases, University of FloridaGainesvilleUnited States
- Evelyn F. and William L. McKnight Brain Institute, University of FloridaGainesvilleUnited States
| | - Charles J Frazier
- Department of Pharmacodynamics, College of Pharmacy, University of FloridaGainesvilleUnited States
- Center for Integrative Cardiovascular and Metabolic Diseases, University of FloridaGainesvilleUnited States
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9
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Littlefield PD, Richter C. Near-infrared stimulation of the auditory nerve: A decade of progress toward an optical cochlear implant. Laryngoscope Investig Otolaryngol 2021; 6:310-319. [PMID: 33869763 PMCID: PMC8035937 DOI: 10.1002/lio2.541] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 12/14/2020] [Accepted: 02/12/2021] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES We provide an appraisal of recent research on stimulation of the auditory system with light. In particular, we discuss direct infrared stimulation and ongoing controversies regarding the feasibility of this modality. We also discuss advancements and barriers to the development of an optical cochlear implant. METHODS This is a review article that covers relevant animal studies. RESULTS The auditory system has been stimulated with infrared light, and in a much more spatially selective manner than with electrical stimulation. However, there are experiments from other labs that have not been able to reproduce these results. This has resulted in an ongoing controversy regarding the feasibility of infrared stimulation, and the reasons for these experimental differences still require explanation. The neural response characteristics also appear to be much different than with electrical stimulation. The electrical stimulation paradigms used for modern cochlear implants do not apply well to optical stimulation and new coding strategies are under development. Stimulation with infrared light brings the risk of heat accumulation in the tissue at high pulse repetition rates, so optimal pulse shapes and combined optical/electrical stimulation are being investigated to mitigate this. Optogenetics is another promising technique, which makes neurons more sensitive to light stimulation by inserting light sensitive ion channels via viral vectors. Challenges of optogenetics include the expression of light sensitive channels in sufficient density in the target neurons, and the risk of damaging neurons by the expression of a foreign protein. CONCLUSION Optical stimulation of the nervous system is a promising new field, and there has been progress toward the development of a cochlear implant that takes advantage of the benefits of optical stimulation. There are barriers, and controversies, but so far none that seem intractable. LEVEL OF EVIDENCE NA (animal studies and basic research).
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Affiliation(s)
| | - Claus‐Peter Richter
- Department of OtolaryngologyNorthwestern UniversityChicagoIllinoisUSA
- Department of Communication Sciences and DisordersNorthwestern UniversityEvanstonIllinoisUSA
- Department of Biomedical EngineeringNorthwestern UniversityEvanstonIllinoisUSA
- The Hugh Knowles Center, Department of Communication Sciences and DisordersNorthwestern UniversityEvanstonIllinoisUSA
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10
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Xu Y, Magnuson M, Agarwal A, Tan X, Richter CP. Infrared neural stimulation at different wavelengths and pulse shapes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 162:89-100. [PMID: 33359901 DOI: 10.1016/j.pbiomolbio.2020.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 11/26/2020] [Accepted: 12/18/2020] [Indexed: 11/30/2022]
Abstract
Neural stimulation with infrared radiation has been explored for brain tissue, peripheral nerves, and cranial nerves including the auditory nerve. Initial experiments were conducted at wavelengths between λ = 1850 and λ = 2140 nm and the radiant energy was delivered with square pulses. Water absorption of the infrared radiation at λ = 1860 nm is similar to absorption at wavelengths between λ = 1310 and λ = 1600 nm, which are in the radiation wavelength range used for the communication industry. Technology for those wavelengths has already been developed and miniaturized and is readily available. The possibility of the infrared light to evoke compound action potentials (CAP) in the cochlea at λ = 1,375, λ = 1,460, and λ = 1550 nm was explored and compared to that of λ = 1860 nm in guinea pigs. Furthermore, rise and fall times of the 100 μs long pulses were changed and four basic pulse shapes (square, triangular, ramp-up, and ramp-down) were explored in their ability to evoke a CAP. In animals with pure tone threshold averages (PTAs) above 70 dB SPL, the results show that the favorable wavelength is λ = 1460 nm to reach threshold for stimulation and λ = 1375 nm or λ = 1460 nm for obtaining maximum amplitude. The most favorable pulse shape is either ramp-up or triangular.
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Affiliation(s)
- Yingyue Xu
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave, Searle 12-561, Chicago, IL, 60611, USA; Department of Communication Sciences and Disorders, Northwestern University, Frances Searle Building, 2240 Campus Drive, Evanston, IL, 60208, USA
| | - Mario Magnuson
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave, Searle 12-561, Chicago, IL, 60611, USA
| | - Aditi Agarwal
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave, Searle 12-561, Chicago, IL, 60611, USA
| | - Xiaodong Tan
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave, Searle 12-561, Chicago, IL, 60611, USA
| | - Claus-Peter Richter
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave, Searle 12-561, Chicago, IL, 60611, USA; Department of Communication Sciences and Disorders, Northwestern University, Frances Searle Building, 2240 Campus Drive, Evanston, IL, 60208, USA; Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Tech E310, Evanston, IL, 60208, USA; The Hugh Knowles Center, Northwestern University, Frances Searle Building, 2240 Campus Drive, Evanston, IL, 60208, USA.
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11
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Armstrong LE, Giersch GEW, Colburn AT, Lopez V, Sekiguchi Y, Muñoz CX, Lee EC. Progression of human subjective perceptions during euhydration, mild dehydration, and drinking. Physiol Behav 2020; 229:113211. [PMID: 33141048 DOI: 10.1016/j.physbeh.2020.113211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 10/12/2020] [Accepted: 10/13/2020] [Indexed: 01/09/2023]
Abstract
Thirst motivates consumption of water necessary for optimal health and cognitive-physiological functions. Other than thirst, little is known about coexisting perceptions and moods that provide information to the brain and participate in body water homeostasis. The purpose of this investigation was to observe perceptions, somatic sensations, and moods during controlled changes of hydration status. During routine daily activities interspersed with laboratory visits, 18 healthy young men (age, 23±3 y; body mass, 80.13±10.61 kg) self-reported hourly ratings (visual analog scales, VAS) of 17 subjective perceptions, across two 24-h periods (ad libitum food and water intake while euhydrated; water restriction with dry food intake [WR]) and during a 30-min rehydration session (R30, 1.46±0.47 L water intake). At the end of WR, body mass loss reached 1.67 kg (2.12%). Distinct perceptions were identified during euhydration, WR and immediately after R30. Starting approximately 4 h after WR began (body mass loss of ∼0.5%), perceptual changes included progressively intensifying ratings of thirst, mouth dryness, desire for water, and pleasantness of drinking. In comparison, immediately after R30, participants reported a reversal of the perceptions observed during WR (above) plus cooler thermal sensation, increased satisfaction, and stomach fullness. These VAS ratings suggested that aversive moods contributed to drinking behavior and supported previously published animal studies. In conclusion, this investigation delineates previously unreported perceptions and their evolution (e.g., appearance, extinction, time course) that motivated drinking during WR and discouraged overdrinking after R30.
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Affiliation(s)
- Lawrence E Armstrong
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States; Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, United States.
| | - Gabrielle E W Giersch
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
| | - Abigail T Colburn
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
| | - Virgilio Lopez
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
| | - Yasuki Sekiguchi
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
| | - Colleen X Muñoz
- Department of Health Sciences, University of Hartford, West Hartford, CT, 06117 United States.
| | - Elaine C Lee
- Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT 06269, United States.
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12
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Drummond LR, Campos HO, de Andrade Lima PM, da Fonseca CG, Kunstetter AC, Rodrigues QT, Szawka RE, Natali AJ, Prímola-Gomes TN, Wanner SP, Coimbra CC. Impaired thermoregulation in spontaneously hypertensive rats during physical exercise is related to reduced hypothalamic neuronal activation. Pflugers Arch 2020; 472:1757-1768. [PMID: 33040159 DOI: 10.1007/s00424-020-02474-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/05/2020] [Accepted: 10/06/2020] [Indexed: 12/25/2022]
Abstract
This study aimed to evaluate the physical exercise-induced neuronal activation in brain nuclei controlling thermoregulatory responses in hypertensive and normotensive rats. Sixteen-week-old male normotensive Wistar rats (NWRs) and spontaneously hypertensive rats (SHRs) were implanted with an abdominal temperature sensor. After recovery, the animals were subjected to a constant-speed treadmill running (at 60% of the maximum aerobic speed) for 30 min at 25 °C. Core (Tcore) and tail-skin (Tskin) temperatures were measured every minute during exercise. Ninety minutes after the exercise, the rats were euthanized, and their brains were collected to determine the c-Fos protein expression in the following areas that modulate thermoregulatory responses: medial preoptic area (mPOA), paraventricular hypothalamic nucleus (PVN), and supraoptic nucleus (SON). During treadmill running, the SHR group exhibited a greater increase in Tcore and an augmented threshold for cutaneous heat loss relative to the NWR group. In addition, the SHRs showed reduced neuronal activation in the mPOA (< 49.7%) and PVN (< 44.2%), but not in the SON. The lower exercise-induced activation in the mPOA and PVN in hypertensive rats was strongly related to the delayed onset of cutaneous heat loss. We conclude that the enhanced exercise-induced hyperthermia in hypertensive rats can be partially explained by a delayed cutaneous heat loss, which is, in turn, associated with reduced activation of brain areas modulating thermoregulatory responses.
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Affiliation(s)
- Lucas Rios Drummond
- Laboratório de Endocrinologia e Metabolismo, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627., Belo Horizonte, MG, 31270-901, Brazil.
| | - Helton Oliveira Campos
- Laboratório de Endocrinologia e Metabolismo, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627., Belo Horizonte, MG, 31270-901, Brazil
| | - Paulo Marcelo de Andrade Lima
- Laboratório de Endocrinologia e Metabolismo, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627., Belo Horizonte, MG, 31270-901, Brazil
| | - Cletiana Gonçalves da Fonseca
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Ana Cançado Kunstetter
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Quezia Teixeira Rodrigues
- Laboratório de Endocrinologia e Metabolismo, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627., Belo Horizonte, MG, 31270-901, Brazil
| | - Raphael Escorsim Szawka
- Laboratório de Endocrinologia e Metabolismo, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627., Belo Horizonte, MG, 31270-901, Brazil
| | - Antônio José Natali
- Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Thales Nicolau Prímola-Gomes
- Laboratório de Biologia do Exercício, Departamento de Educação Física, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Samuel Penna Wanner
- Laboratório de Fisiologia do Exercício, Departamento de Educação Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Cândido Celso Coimbra
- Laboratório de Endocrinologia e Metabolismo, Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627., Belo Horizonte, MG, 31270-901, Brazil
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Yonghak P, Miyata S, Kurganov E. TRPV1 is crucial for thermal homeostasis in the mouse by heat loss behaviors under warm ambient temperature. Sci Rep 2020; 10:8799. [PMID: 32472067 PMCID: PMC7260197 DOI: 10.1038/s41598-020-65703-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 05/04/2020] [Indexed: 11/12/2022] Open
Abstract
Thermal homeostasis in mammalians is a self-regulating process by which biological systems maintain an internal thermal stability, even under different temperature conditions; however, the molecular mechanisms involved under warm ambient temperature remain unclear. Here, we aimed to clarify functional significance of transient receptor potential vanilloid receptor 1 (TRPV1) under warm ambient temperature. TRPV1 KO mice exhibited transient hyperthermia when exposed to 30.0 and 32.5 °C, whereas wild-type (WT) mice did not. TRPV1 KO mice exhibited prolonged and prominent hyperthermia upon exposure to 35.0 °C, whereas WT mice showed transient hyperthermia. Hyperthermia also occurs in WT mice that received intracerebroventricular injection of TRPV1 antagonist AMG9810 upon exposure to 35.0 °C. Heat loss behaviors, sleeping and body licking, were deficient in TRPV1 KO mice exposed to warm temperatures. Therefore, the present results indicate that central TRPV1 is crucial for maintaining a constant body temperature via the initiation of heat loss behaviors under warm ambient temperature.
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Affiliation(s)
- Park Yonghak
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Seiji Miyata
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Erkin Kurganov
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
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14
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Leng G, Russell JA. The osmoresponsiveness of oxytocin and vasopressin neurones: Mechanisms, allostasis and evolution. J Neuroendocrinol 2019; 31:e12662. [PMID: 30451331 DOI: 10.1111/jne.12662] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/29/2018] [Accepted: 11/15/2018] [Indexed: 12/27/2022]
Abstract
In the rat supraoptic nucleus, every oxytocin cell projects to the posterior pituitary, and is involved both in reflex milk ejection during lactation and in regulating uterine contractions during parturition. All are also osmosensitive, regulating natriuresis. All are also regulated by signals that control appetite, including the neural and hormonal signals that arise from the gut after food intake and from the sites of energy storage. All are also involved in sexual behaviour, anxiety-related behaviours and social behaviours. The challenge is to understand how a single population of neurones can coherently regulate such a diverse set of functions and adapt to changing physiological states. Their multiple functions arise from complex intrinsic properties that confer sensitivity to a wide range of internal and environmental signals. Many of these properties have a distant evolutionary origin in multifunctional, multisensory neurones of Urbilateria, the hypothesised common ancestor of vertebrates, insects and worms. Their properties allow different patterns of oxytocin release into the circulation from their axon terminals in the posterior pituitary into other brain areas from axonal projections, as well as independent release from their dendrites.
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Affiliation(s)
- Gareth Leng
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, UK
| | - John A Russell
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, UK
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15
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Xu Y, Xia N, Lim M, Tan X, Tran MH, Boulger E, Peng F, Young H, Rau C, Rack A, Richter CP. Multichannel optrodes for photonic stimulation. NEUROPHOTONICS 2018; 5:045002. [PMID: 30397630 PMCID: PMC6197865 DOI: 10.1117/1.nph.5.4.045002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 09/24/2018] [Indexed: 05/27/2023]
Abstract
An emerging method in the field of neural stimulation is the use of photons to activate neurons. The possible advantage of optical stimulation over electrical is attributable to its spatially selective activation of small neuron populations, which is promising in generating superior spatial resolution in neural interfaces. Two principal methods are explored for cochlear prostheses: direct stimulation of nerves with infrared light and optogenetics. This paper discusses basic requirements for developing a light delivery system (LDS) for the cochlea and provides examples for building such devices. The proposed device relies on small optical sources, which are assembled in an array to be inserted into the cochlea. The mechanical properties, the biocompatibility, and the efficacy of optrodes have been tested in animal models. The force required to insert optrodes into a model of the human scala tympani was comparable to insertion forces obtained for contemporary cochlear implant electrodes. Side-emitting diodes are powerful enough to evoke auditory responses in guinea pigs. Chronic implantation of the LDS did not elevate auditory brainstem responses over 26 weeks.
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Affiliation(s)
- Yingyue Xu
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, Chicago, Illinois, United States
- Northwestern University, Department of Communication Sciences and Disorders, Evanston, Illinois, United States
| | - Nan Xia
- Qingdao University, Institute for Digital Medicine and Computer-assisted Surgery, Qingdao, China
| | - Michelle Lim
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, Chicago, Illinois, United States
| | - Xiaodong Tan
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, Chicago, Illinois, United States
| | - Minh Ha Tran
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, Chicago, Illinois, United States
| | - Erin Boulger
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, Chicago, Illinois, United States
| | - Fei Peng
- Chongqing University, Bioengineering College, Chongqing, China
| | - Hunter Young
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, Chicago, Illinois, United States
| | - Christoph Rau
- Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom
| | - Alexander Rack
- Structure of Materials Group-ID19, European Synchrotron Radiation Facility, Cedex 9, France
| | - Claus-Peter Richter
- Northwestern University Feinberg School of Medicine, Department of Otolaryngology, Chicago, Illinois, United States
- Northwestern University, Department of Communication Sciences and Disorders, Evanston, Illinois, United States
- Northwestern University, Department of Biomedical Engineering, Evanston, Illinois, United States
- Northwestern University, Hugh Knowles Center for Clinical and Basic Sciences in Hearing, Evanston, Illinois, United States
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Kurt G, Woodworth HL, Fowler S, Bugescu R, Leinninger GM. Activation of lateral hypothalamic area neurotensin-expressing neurons promotes drinking. Neuropharmacology 2018; 154:13-21. [PMID: 30266601 DOI: 10.1016/j.neuropharm.2018.09.038] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 09/04/2018] [Accepted: 09/24/2018] [Indexed: 12/18/2022]
Abstract
Animals must ingest water via drinking to maintain fluid homeostasis, yet the neurons that specifically promote drinking behavior are incompletely characterized. The lateral hypothalamic area (LHA) as a whole is essential for drinking behavior but most LHA neurons indiscriminately promote drinking and feeding. By contrast, activating neurotensin (Nts)-expressing LHA neurons (termed LHA Nts neurons) causes mice to immediately drink water with a delayed suppression of feeding. We therefore hypothesized that LHA Nts neurons are sufficient to induce drinking behavior and that these neurons specifically bias for fluid intake over food intake. To test this hypothesis we used designer receptors exclusively activated by designer drugs (DREADDs) to selectively activate LHA Nts neurons and studied the impact on fluid intake, fluid preference and feeding. Activation of LHA Nts neurons stimulated drinking in water-replete and dehydrated mice, indicating that these neurons are sufficient to promote water intake regardless of homeostatic need. Interestingly, mice with activated LHA Nts neurons drank any fluid that was provided regardless of its palatability, but if given a choice they preferred water or palatable solutions over unpalatable (quinine) or dehydrating (hypertonic saline) solutions. Notably, acute activation of LHA Nts neurons robustly promoted fluid but not food intake. Overall, our study confirms that activation of LHA Nts neurons is sufficient to induce drinking behavior and biases for fluid intake. Hence, LHA Nts neurons may be important targets for orchestrating the appropriate ingestive behavior necessary to maintain fluid homeostasis. This article is part of the Special Issue entitled 'Hypothalamic Control of Homeostasis'.
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Affiliation(s)
- Gizem Kurt
- Department of Physiology, Michigan State University, East Lansing, MI, 48114, USA
| | - Hillary L Woodworth
- Department of Physiology, Michigan State University, East Lansing, MI, 48114, USA
| | - Sabrina Fowler
- Department of Physiology, Michigan State University, East Lansing, MI, 48114, USA
| | - Raluca Bugescu
- Department of Physiology, Michigan State University, East Lansing, MI, 48114, USA
| | - Gina M Leinninger
- Department of Physiology, Michigan State University, East Lansing, MI, 48114, USA.
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17
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Stacey MJ, Woods DR, Brett SJ, Britland SE, Fallowfield JL, Allsopp AJ, Delves SK. Heat acclimatization blunts copeptin responses to hypertonicity from dehydrating exercise in humans. Physiol Rep 2018; 6:e13851. [PMID: 30221840 PMCID: PMC6139708 DOI: 10.14814/phy2.13851] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 08/04/2018] [Accepted: 08/10/2018] [Indexed: 11/24/2022] Open
Abstract
Acclimatization favors greater extracellular tonicity from lower sweat sodium, yet hyperosmolality may impair thermoregulation during heat stress. Enhanced secretion or action of vasopressin could mitigate this through increased free water retention. Aims were to determine responses of the vasopressin surrogate copeptin to dehydrating exercise and investigate its relationships with tonicity during short and long-term acclimatization. Twenty-three participants completed a structured exercise programme following arrival from a temperate to a hot climate. A Heat Tolerance Test (HTT) was conducted on Day-2, 6, 9 and 23, consisting of 60-min block-stepping at 50% VO2 peak, with no fluid intake. Resting sweat [Na+ ] was measured by iontophoresis. Changes in body mass (sweat loss), core temperature, heart rate, osmolality (serum and urine) and copeptin and aldosterone (plasma) were measured with each Test. From Day 2 to Day 23, sweat [Na+ ] decreased significantly (adjusted P < 0.05) and core temperature and heart rate fell. Over the same interval, HTT-associated excursions were increased for serum osmolality (5 [-1, 9] vs. 9 [5, 12] mosm·kg-1 ), did not differ for copeptin (9.6 [6.0, 15.0] vs. 7.9 [4.3, 14.7] pmol·L-1 ) and were reduced for aldosterone (602 [415, 946] vs. 347 [263, 537] pmol·L-1 ). Urine osmolality was unchanging and related consistently to copeptin at end-exercise, whereas the association between copeptin and serum osmolality was right-shifted (P = 0.0109) with acclimatization. Unchanging urine:serum osmolality argued against increased renal action of vasopressin. In conclusion, where exercise in the heat is performed without fluid replacement, heat acclimatization does not appear to enhance AVP-mediated free water retention in humans.
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Affiliation(s)
- Michael J. Stacey
- Department of Surgery and CancerImperial College LondonLondonUnited Kingdom
- Department of Military MedicineRoyal Centre for Defence MedicineBirminghamUnited Kingdom
| | - David R. Woods
- Department of Surgery and CancerImperial College LondonLondonUnited Kingdom
- Carnegie Research InstituteLeeds Beckett UniversityLeedsUnited Kingdom
| | - Stephen J. Brett
- Department of Surgery and CancerImperial College LondonLondonUnited Kingdom
| | | | | | | | - Simon K. Delves
- Institute of Naval MedicineAlverstokeHampshireUnited Kingdom
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18
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Abstract
Water intake is one of the most basic physiological responses and is essential to sustain life. The perception of thirst has a critical role in controlling body fluid homeostasis and if neglected or dysregulated can lead to life-threatening pathologies. Clear evidence suggests that the perception of thirst occurs in higher-order centres, such as the anterior cingulate cortex (ACC) and insular cortex (IC), which receive information from midline thalamic relay nuclei. Multiple brain regions, notably circumventricular organs such as the organum vasculosum lamina terminalis (OVLT) and subfornical organ (SFO), monitor changes in blood osmolality, solute load and hormone circulation and are thought to orchestrate appropriate responses to maintain extracellular fluid near ideal set points by engaging the medial thalamic-ACC/IC network. Thirst has long been thought of as a negative homeostatic feedback response to increases in blood solute concentration or decreases in blood volume. However, emerging evidence suggests a clear role for thirst as a feedforward adaptive anticipatory response that precedes physiological challenges. These anticipatory responses are promoted by rises in core body temperature, food intake (prandial) and signals from the circadian clock. Feedforward signals are also important mediators of satiety, inhibiting thirst well before the physiological state is restored by fluid ingestion. In this Review, we discuss the importance of thirst for body fluid balance and outline our current understanding of the neural mechanisms that underlie the various types of homeostatic and anticipatory thirst.
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Affiliation(s)
- Claire Gizowski
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre and Montreal General Hospital, 1650 Cedar Avenue, Montreal H3G1A4, Canada
| | - Charles W Bourque
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre and Montreal General Hospital, 1650 Cedar Avenue, Montreal H3G1A4, Canada
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19
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Stacey MJ, Delves SK, Britland SE, Allsopp AJ, Brett SJ, Fallowfield JL, Woods DR. Copeptin reflects physiological strain during thermal stress. Eur J Appl Physiol 2017; 118:75-84. [PMID: 29075863 PMCID: PMC5754412 DOI: 10.1007/s00421-017-3740-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 10/08/2017] [Indexed: 11/22/2022]
Abstract
Purpose To prevent heat-related illnesses, guidelines recommend limiting core body temperature (Tc) ≤ 38 °C during thermal stress. Copeptin, a surrogate for arginine vasopressin secretion, could provide useful information about fluid balance, thermal strain and health risks. It was hypothesised that plasma copeptin would rise with dehydration from occupational heat stress, concurrent with sympathoadrenal activation and reduced glomerular filtration, and that these changes would reflect Tc responses. Methods Volunteers (n = 15) were recruited from a British Army unit deployed to East Africa. During a simulated combat assault (3.5 h, final ambient temperature 27 °C), Tc was recorded by radiotelemetry to differentiate volunteers with maximum Tc > 38 °C versus ≤ 38 °C. Blood was sampled beforehand and afterwards, for measurement of copeptin, cortisol, free normetanephrine, osmolality and creatinine. Results There was a significant (P < 0.05) rise in copeptin from pre- to post-assault (10.0 ± 6.3 vs. 16.7 ± 9.6 pmol L−1, P < 0.001). Although osmolality did not increase, copeptin correlated strongly with osmolality after the exposure (r = 0.70, P = 0.004). In volunteers with maximum Tc > 38 °C (n = 8) vs ≤ 38 °C (n = 7) there were significantly greater elevations in copeptin (10.4 vs. 2.4 pmol L−1) and creatinine (10 vs. 2 μmol L−1), but no differences in cortisol, free normetanephrine or osmolality. Conclusions Changes in copeptin reflected Tc response more closely than sympathoadrenal markers or osmolality. Dynamic relationships with tonicity and kidney function may help to explain this finding. As a surrogate for integrated physiological strain during work in a field environment, copeptin assay could inform future measures to prevent heat-related illnesses.
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Affiliation(s)
- Michael John Stacey
- Department of Surgery and Cancer, Imperial College London, Care of General Intensive Care Unit, Hammersmith Hospital Campus, Du Cane Road, London, W12 0HS, UK. .,Department of Military Medicine, Royal Centre for Defence Medicine, ICT Building, Birmingham Research Park, Vincent Drive, Edgbaston, Birmingham, B15 2SQ, UK.
| | - Simon K Delves
- Institute of Naval Medicine, Alverstoke, Hampshire, PO12 2DL, UK
| | | | - Adrian J Allsopp
- Institute of Naval Medicine, Alverstoke, Hampshire, PO12 2DL, UK
| | - Stephen J Brett
- Department of Surgery and Cancer, Imperial College London, Care of General Intensive Care Unit, Hammersmith Hospital Campus, Du Cane Road, London, W12 0HS, UK
| | | | - David R Woods
- Department of Military Medicine, Royal Centre for Defence Medicine, ICT Building, Birmingham Research Park, Vincent Drive, Edgbaston, Birmingham, B15 2SQ, UK.,Carnegie Research Institute, Leeds Beckett University, Leeds, LS6 3QS, UK
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20
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Johnson CR, Porter SG, Coats D, Whitfield KC, Mengkheang K, Topazian MD, Fischer PR. No Camphor Toxicity in Cambodian Infants. Glob Pediatr Health 2017; 4:2333794X17702980. [PMID: 28491925 PMCID: PMC5406147 DOI: 10.1177/2333794x17702980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Accepted: 02/26/2017] [Indexed: 11/17/2022] Open
Abstract
Thiamine deficiency and beriberi are prevalent in Cambodia, although most infants with nonspecific clinical symptoms of beriberi, including tachypnea, lack echocardiographic evidence diagnostic of the disease. Camphor activates transient receptor potential vanilloid 3 (TRPV3), a nonselective ion channel expressed in the medial preoptic nucleus of the hypothalamus and thought to be important for thermo-sensitivity. Because camphorated ointments are used commonly among Cambodian infants, we hypothesized that topical camphor modulates thermoregulatory behaviors, causing beriberi-simulating tachypnea, separate from any influence of thiamine deficiency. We assessed 9 tachypneic and 10 healthy infants for Tiger Balm use and for presence of camphor in whole blood. However, no camphor was found in blood from any infants, indicating that camphor is unrelated to tachypneic illness in Cambodian infants.
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Affiliation(s)
| | - Samuel G Porter
- Via Christi Medical Center, Wichita, KS, USA.,University of Kansas, Lawrence, KS, USA
| | - Debra Coats
- Eastern Mennonite Missions, Prey Veng, Cambodia
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21
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Agnati LF, Marcoli M, Leo G, Maura G, Guidolin D. Homeostasis and the concept of 'interstitial fluids hierarchy': Relevance of cerebrospinal fluid sodium concentrations and brain temperature control (Review). Int J Mol Med 2017; 39:487-497. [PMID: 28204813 PMCID: PMC5360360 DOI: 10.3892/ijmm.2017.2874] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 12/12/2016] [Indexed: 12/21/2022] Open
Abstract
In this review, the aspects and further developments of the concept of homeostasis are discussed also in the perspective of their possible impact in the clinical practice, particularly as far as psychic homeostasis is concerned. A brief historical survey and comments on the concept of homeostasis and allostasis are presented to introduce our proposal that is based on the classical assumption of the interstitial fluid (ISF) as the internal medium for multicellular organisms. However, the new concept of a hierarchic role of ISF of the various organs is introduced. Additionally, it is suggested that particularly for some chemico‑physical parameters, oscillatory rhythms within their proper set‑ranges should be considered a fundamental component of homeostasis. Against this background, we propose that the brain ISF has the highest hierarchic role in human beings, providing the optimal environment, not simply for brain cell survival, but also for brain complex functions and the oscillatory rhythms of some parameters, such as cerebrospinal fluid sodium and brain ISF pressure waves, which may play a crucial role in brain physio‑pathological states. Thus, according to this proposal, the brain ISF represents the real internal medium since the maintenance of its dynamic intra-set-range homeostasis is the main factor for a free and independent life of higher vertebrates. Furthermore, the evolutionary links between brain and kidney and their synergistic role in H2O/Na balance and brain temperature control are discussed. Finally, it is surmised that these two interrelated parameters have deep effects on the Central Nervous System (CNS) higher integrative actions such those linked to psychic homeostasis.
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Affiliation(s)
- Luigi F Agnati
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41121 Modena, Italy
| | - Manuela Marcoli
- Department of Pharmacy, Unit of Pharmacology and Toxicology, and Center of Excellence for Biomedical Research, University of Genova, 16126 Genova, Italy
| | - Giuseppina Leo
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41121 Modena, Italy
| | - Guido Maura
- Department of Pharmacy, Unit of Pharmacology and Toxicology, and Center of Excellence for Biomedical Research, University of Genova, 16126 Genova, Italy
| | - Diego Guidolin
- Department of Molecular Medicine, University of Padova, 35121 Padova, Italy
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22
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Xia N, Tan X, Xu Y, Hou W, Mao T, Richter CP. Pressure in the Cochlea During Infrared Irradiation. IEEE Trans Biomed Eng 2016; 65:1575-1584. [PMID: 27959792 DOI: 10.1109/tbme.2016.2636149] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE The purpose of the study is to demonstrate laser-evoked pressure waves in small confined volumes such as the cochlea. METHODS Custom-fabricated pressure probes were used to determine the pressure in front of the optical fiber in a small dish and patch pipettes to measure temperature changes. Pressure probes were inserted into scala tympani (ST) or vestibuli during laser stimulation. With a sensitive microphone the pressure was measured in the outer ear canal. RESULTS Heating was spatially confined. The heat relaxation time was 35 ms. During laser stimulation in the cochlea at 17 μJ/pulse, the pressure in the outer ear canal (EC) was 43.5 dB (re 20 μPa). The corresponding intracochlear pressure was calculated to be about 78.5 dB (re 20 μPa) using the middle ear reverse transfer function of -35 dB. At 164 μJ/pulse, the pressure in the EC was on average 63 dB (re 20 μPa) and the intracochlear pressure was estimated to be 98 dB (re 20 μPa), which is similar to the value obtained with the pressure probe, 100 dB (re 20 μPa). Side-emitting optical fibers were used to steer the beam path. The pressure values were independent of the orientation of the beam path. Evoked compound action potentials of the auditory nerve were maximum when spiral ganglion neurons were in the beam path. CONCLUSION Pressure waves are generated during infrared laser stimulation. The intracochlear pressure was independent from the orientation of the beam path. SIGNIFICANCE Neural responses required the spiral ganglion neurons to be directly irradiated.
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Kamakura T, Kondo M, Koyama Y, Hanada Y, Ishida Y, Nakamura Y, Yamada T, Takimoto Y, Kitahara T, Ozono Y, Horii A, Imai T, Inohara H, Shimada S. Functional Expression of an Osmosensitive Cation Channel, Transient Receptor Potential Vanilloid 4, in Rat Vestibular Ganglia. Audiol Neurootol 2016; 21:268-274. [PMID: 27705979 DOI: 10.1159/000449238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 08/18/2016] [Indexed: 11/19/2022] Open
Abstract
Transient receptor potential vanilloid (TRPV) 4 is a nonselective cation channel expressed in sensory neurons such as those in the dorsal root and trigeminal ganglia, kidney, and inner ear. TRPV4 is activated by mechanical stress, heat, low osmotic pressure, low pH, and phorbol derivatives such as 4α-phorbol 12,13-didecanoate (4α-PDD). We investigated the expression of TRPV4 in rat vestibular ganglion (VG) neurons. The TRPV4 gene was successfully amplified from VG neuron mRNA using reverse-transcription polymerase chain reaction. Furthermore, immunoblotting showed positive expression of TRPV4 protein in VG neurons. Immunohistochemistry indicated that TRPV4 was localized predominantly on the plasma membrane of VG neurons. Calcium (Ca2+) imaging of VG neurons showed that 4α-PDD and/or hypotonic stimuli caused an increase in intracellular Ca2+ concentration ([Ca2+]i) that was almost completely inhibited by ruthenium red, a selective antagonist of TRPV channels. Interestingly, a [Ca2+]i increase was evoked by both hypotonic stimuli and 4α-PDD in approximately 38% of VG neurons. These data indicate that TRPV4 is functionally expressed in VG neurons as an ion channel and that TRPV4 likely participates in VG neurons for vestibular neurotransmission as an osmoreceptor and/or mechanoreceptor.
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Affiliation(s)
- Takefumi Kamakura
- Department of Otorhinolaryngology - Head and Neck Surgery, Osaka University Graduate School of Medicine, Suita, Japan
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TRPV1 is crucial for proinflammatory STAT3 signaling and thermoregulation-associated pathways in the brain during inflammation. Sci Rep 2016; 6:26088. [PMID: 27188969 PMCID: PMC4870621 DOI: 10.1038/srep26088] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 04/25/2016] [Indexed: 01/06/2023] Open
Abstract
Transient receptor potential vanilloid receptor 1 (TRPV1) is a non-selective cation channel that is stimulated by heat (>43 °C), mechanical/osmotic stimuli, and low pH. The importance of TRPV1 in inflammatory responses has been demonstrated, whereas its participation in brains remains unclear. In the present study, the intracerebroventricular (icv) administration of the TRPV1 agonist resiniferatoxin (RTX) induced the activation of signal transducer and activator of transcription 3 (STAT3) in circumventricular organs (CVOs) and thermoregulation-associated brain regions with a similar patttern to the peripheral and icv administration of lipopolysaccharide (LPS). With the peripheral and icv LPS stimuli, STAT3 activation was significantly lower in Trpv1−/− mice than in Trpv1+/+ mice. The icv administration of RTX induced transient hypothermia, whereas that of the TRPV1 antagonist capsazepine enhanced the magnitude and period of LPS-induced hyperthermia. These results indicate that TRPV1 is important for activating proinflammatory STAT3 signaling and thermoregulation-associated brain pathways in the brain.
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Miyata S. New aspects in fenestrated capillary and tissue dynamics in the sensory circumventricular organs of adult brains. Front Neurosci 2015; 9:390. [PMID: 26578857 PMCID: PMC4621430 DOI: 10.3389/fnins.2015.00390] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 10/05/2015] [Indexed: 12/20/2022] Open
Abstract
The blood-brain barrier (BBB) generally consists of endothelial tight junction barriers that prevent the free entry of blood-derived substances, thereby maintaining the extracellular environment of the brain. However, the circumventricular organs (CVOs), which are located along the midlines of the brain ventricles, lack these endothelial barriers and have fenestrated capillaries; therefore, they have a number of essential functions, including the transduction of information between the blood circulation and brain. Previous studies have demonstrated the extensive contribution of the CVOs to body fluid and thermal homeostasis, energy balance, the chemoreception of blood-derived substances, and neuroinflammation. In this review, recent advances have been discussed in fenestrated capillary characterization and dynamic tissue reconstruction accompanied by angiogenesis and neurogliogenesis in the sensory CVOs of adult brains. The sensory CVOs, including the organum vasculosum of the lamina terminalis (OVLT), subfornical organ (SFO), and area postrema (AP), have size-selective and heterogeneous vascular permeabilities. Astrocyte-/tanycyte-like neural stem cells (NSCs) sense blood- and cerebrospinal fluid-derived information through the transient receptor potential vanilloid 1, a mechanical/osmotic receptor, Toll-like receptor 4, a lipopolysaccharide receptor, and Nax, a Na-sensing Na channel. They also express tight junction proteins and densely and tightly surround mature neurons to protect them from blood-derived neurotoxic substances, indicating that the NSCs of the CVOs perform BBB functions while maintaining the capacity to differentiate into new neurons and glial cells. In addition to neurogliogenesis, the density of fenestrated capillaries is regulated by angiogenesis, which is accompanied by the active proliferation and sprouting of endothelial cells. Vascular endothelial growth factor (VEGF) signaling may be involved in angiogenesis and neurogliogenesis, both of which affect vascular permeability. Thus, recent findings advocate novel concepts for the CVOs, which have the dynamic features of vascular and parenchymal tissues.
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Affiliation(s)
- Seiji Miyata
- Department of Applied Biology, Kyoto Institute of TechnologyKyoto, Japan
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Zaelzer C, Hua P, Prager-Khoutorsky M, Ciura S, Voisin D, Liedtke W, Bourque C. ΔN-TRPV1: A Molecular Co-detector of Body Temperature and Osmotic Stress. Cell Rep 2015; 13:23-30. [DOI: 10.1016/j.celrep.2015.08.061] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 07/25/2015] [Accepted: 08/21/2015] [Indexed: 10/23/2022] Open
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Sladek CD, Michelini LC, Stachenfeld NS, Stern JE, Urban JH. Endocrine‐Autonomic Linkages. Compr Physiol 2015; 5:1281-323. [DOI: 10.1002/cphy.c140028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Kinsman B, Cowles J, Lay J, Simmonds SS, Browning KN, Stocker SD. Osmoregulatory thirst in mice lacking the transient receptor potential vanilloid type 1 (TRPV1) and/or type 4 (TRPV4) receptor. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1092-100. [PMID: 25100078 DOI: 10.1152/ajpregu.00102.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent studies suggest the ability of the central nervous system to detect changes in osmolality is mediated by products of the genes encoding the transient receptor potential vanilloid-1 (TRPV1) or vanilloid-4 (TRPV4) channel. The purpose of the present study was to determine whether deletion of TRPV1 and/or TRPV4 channels altered thirst responses to cellular dehydration in mice. Injection of 0.5 or 1.0 M NaCl produced dose-dependent increases in cumulative water intakes of wild-type (WT), TRPV1-/-, TRPV4-/-, and TRPV1-/-V4-/- mice. However, there were no differences in cumulative water intakes between WT versus any other strain despite similar increases in plasma electrolytes and osmolality. Similar results were observed after injection of hypertonic mannitol. This was a consistent finding regardless of the injection route (intraperitoneal vs. subcutaneous) or timed access to water (delayed vs. immediate). There were also no differences in cumulative intakes across strains after injection of 0.15 M NaCl or during a time-controlled period (no injection). Chronic hypernatremia produced by sole access to 2% NaCl for 48 h also produced similar increases in water intake across strains. In a final set of experiments, subcutaneous injection of 0.5 M NaCl produced similar increases in the number of Fos-positive nuclei within the organum vasculosum of the lamina terminalis and median preoptic nucleus across strains but significantly smaller number in the subfornical organ of WT versus TRPV1-/-V4-/- mice. Collectively, these findings suggest that TRPV1 and/or TRPV4 channels are not the primary mechanism by which the central nervous system responds to cellular dehydration during hypernatremia or hyperosmolality to increase thirst.
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Affiliation(s)
- Brian Kinsman
- Department of Cellular and Molecular Physiology, and
| | - James Cowles
- Department of Cellular and Molecular Physiology, and
| | - Jennifer Lay
- Department of Cellular and Molecular Physiology, and
| | | | - Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Sean D Stocker
- Department of Cellular and Molecular Physiology, and Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
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