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Sigurdsson B, Hauglund NL, Lilius TO, Mogensen FLH, Mortensen KN, Beschorner N, Klinger L, Bærentzen SL, Rosenholm MP, Shalgunov V, Herth M, Mori Y, Nedergaard M. A SPECT-based method for dynamic imaging of the glymphatic system in rats. J Cereb Blood Flow Metab 2023; 43:1153-1165. [PMID: 36809165 PMCID: PMC10291457 DOI: 10.1177/0271678x231156982] [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: 08/10/2022] [Revised: 11/17/2022] [Accepted: 12/07/2022] [Indexed: 02/23/2023]
Abstract
The glymphatic system is a brain-wide waste drainage system that promotes cerebrospinal fluid circulation through the brain to remove waste metabolites. Currently, the most common methods for assessing glymphatic function are ex vivo fluorescence microscopy of brain slices, macroscopic cortical imaging, and MRI. While all these methods have been crucial for expanding our understanding of the glymphatic system, new techniques are required to overcome their specific drawbacks. Here, we evaluate SPECT/CT imaging as a tool to assess glymphatic function in different anesthesia-induced brain states using two radiolabeled tracers, [111In]-DTPA and [99mTc]-NanoScan. Using SPECT, we confirmed the existence of brain state-dependent differences in glymphatic flow and we show brain state-dependent differences of CSF flow kinetics and CSF egress to the lymph nodes. We compare SPECT and MRI for imaging glymphatic flow and find that the two imaging modalities show the same overall pattern of CSF flow, but that SPECT was specific across a greater range of tracer concentrations than MRI. Overall, we find that SPECT imaging is a promising tool for imaging the glymphatic system, and that qualities such as high sensitivity and the variety of available tracers make SPECT imaging a good alternative for glymphatic research.
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Affiliation(s)
- Björn Sigurdsson
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
| | - Natalie L Hauglund
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
| | - Tuomas O Lilius
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
- INDIVIDRUG Research Program, University of Helsinki, Finland
- Department of Pharmacology, University of Helsinki, Finland
- Department of Emergency Medicine and Services, Helsinki University Hospital and University of Helsinki, Finland
| | - Frida L-H Mogensen
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
- Neuro-Immunology Group, Department of Cancer Research, Luxembourg Institute of Health, Luxembourg, Luxembourg
- Doctoral School of Science and Technology, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | | | - Natalie Beschorner
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
| | - Laura Klinger
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
| | - Simone L Bærentzen
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Marko P Rosenholm
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
| | - Vladimir Shalgunov
- Department of Drug Design and Pharmacology, University of Copenhagen, Denmark
| | - Matthias Herth
- Department of Drug Design and Pharmacology, University of Copenhagen, Denmark
- Department of Clinical Physiology, Copenhagen University Hospital, Denmark
| | - Yuki Mori
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, USA
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Effects of spinal anesthesia and sedation with dexmedetomidine or propofol on cerebral regional oxygen saturation and systemic oxygenation a period after spinal injection. J Anesth 2020; 34:806-813. [PMID: 32556601 DOI: 10.1007/s00540-020-02816-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 06/12/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE To evaluate changes in cerebral regional oxygen saturation (rSO2) after spinal anesthesia and compare the changes in rSO2 and systemic oxygenation between dexmedetomidine sedation and propofol sedation. METHODS Thirty-six patients scheduled to undergo transurethral surgery under spinal anesthesia were randomly assigned to the dexmedetomidine (n = 18) and propofol groups (n = 18). We used near-infrared spectroscopy sensors to measure rSO2, and obtained data from each side were averaged. After oxygen insufflation, baseline measurements of mean arterial blood pressure (MAP), heart rate, rSO2, pulse oximetry saturation (SpO2), bispectral index, and body temperature were made. After spinal anesthesia, we measured these parameters every 5 min. Twenty minutes after spinal injection, dexmedetomidine or propofol administration was started. We measured each parameter at 10, 25, and 40 min after the administration of dexmedetomidine or propofol. RESULTS The baseline rSO2 in the dexmedetomidine group was 71.3 ± 7.3%, and that in the propofol group was 71.8 ± 5.6%. After spinal anesthesia, rSO2 in both groups decreased significantly (dexmedetomidine group: 65.4 ± 6.9%; propofol group: 64.3 ± 7.4%). After administering sedatives, rSO2 was equivalent after spinal anesthesia. rSO2 was comparable between the two groups. MAP and SpO2 were significantly higher in the dexmedetomidine group than in the propofol group. CONCLUSION Spinal anesthesia decreased rSO2; however, the decline was not severe. Dexmedetomidine and propofol did not compromise cerebral oxygenation under spinal anesthesia. Nevertheless, MAP and SpO2 were more stable in dexmedetomidine sedation than in propofol sedation. Dexmedetomidine may be suitable for spinal anesthesia.
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Tonooka Y, Sunada K. Dexmedetomidine Enhances the Pulpal Anesthetic Effect of Lidocaine: A Pilot Study. Anesth Prog 2018; 65:38-43. [PMID: 29509522 DOI: 10.2344/anpr-65-01-05] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Dexmedetomidine hydrochloride (DEX) demonstrates analgesic, sedative, and hypotensive effects. DEX may also enhance the effect of local anesthetics used in the oral cavity, although this has not been well established in combination with lidocaine. We conducted a single-blind crossover study in 8 healthy volunteers to investigate whether DEX enhances the anesthetic effect of lidocaine in the oral cavity. DEX or DEX + lidocaine was injected into the labial gingiva corresponding to the root apex of the maxillary left central incisor and into the buccal gingiva corresponding to the root apex of the mandibular right first molar. Pain threshold, blood pressure, pulse rate, oxygen saturation, and bispectral index were measured 5 minutes after treatment and at 10-minute intervals for 60 minutes. DEX + lidocaine caused pulpal anesthesia in more subjects than lidocaine alone; this difference was significant for both central incisors and first molars up to 40 minutes after treatment. Following DEX + lidocaine treatment, blood pressure and bispectral index were significantly reduced at several time points, and pulse rate significantly reduced at all time points. Neither treatment caused changes in oxygen saturation. In conclusion, administering DEX with lidocaine for dental local anesthesia caused sedation and enhanced local anesthesia compared to lidocaine alone.
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Affiliation(s)
- Yoko Tonooka
- Department of Dental Anesthesiology, The Nippon Dental University School of Life Dentistry, Tokyo, Japan
| | - Katsuhisa Sunada
- Department of Dental Anesthesiology, The Nippon Dental University School of Life Dentistry, Tokyo, Japan
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Ikemoto K, Ishiyama T, Shintani N, Asano N, Sessler DI, Matsukawa T. The effects of topical and intravenous JM-1232(-) on cerebral pial microvessels of rabbits. BMC Anesthesiol 2015; 15:37. [PMID: 25805961 PMCID: PMC4372327 DOI: 10.1186/s12871-015-0016-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 02/24/2015] [Indexed: 11/30/2022] Open
Abstract
Background JM-1232(-) is a novel anesthetic agent which acts through gamma-aminobutyric acid receptors. Cerebral pial vascular effects of JM-1232(-) are unknown. We thus evaluated topical and intravenous effects of JM-1232(-) on cerebral pial microvessels in rabbits, and the extent to which carbon dioxide (CO2) reactivity is preserved. Methods Closed cranial windows were used to visualize cerebral pial circulation in 29 Japanese white rabbits. In the first experiment, the cranial window was superfused with increasing concentrations of JM-1232(-): 10-11, 10-9, 10-7, 10-5 mol/L, n = 8 per concentration. In the second experiment, we examined the effects of an intravenous bolus of 1 mg/kg bolus of JM-1232(-), followed by the continuous infusion at 0.3 mg/kg/minute on cerebral pial vascular alteration (n = 9). In the third, we examined CO2 reactivity of cerebral pial vessels under JM-1232(-) (n = 6) or sevoflurane anesthesia (n = 6). Results Topical application of JM-1232(-) did not change pial venular diameter, and constricted arterials only at the highest concentration. Intravenous administration of JM-1232(-) produced cerebral pial constriction which gradually diminished over time. Under intravenous administration of JM-1232(-) and inhaled sevoflurane, diameters of vessels increased in parallel with CO2 partial pressure. Slopes of linear regression and correlation coefficients in arterioles and venules were comparable for JM-1232(-) anesthesia and sevoflurane anesthesia. Conclusions Topical application of JM-1232(-) had little effect on cerebral pial vessels. Intravenous administration produced vasoconstriction of cerebral pial arterioles and venules, however those changes were clinically unimportant. In addition, JM-1232(-) did not impair CO2 responsiveness. At least from the perspective of vascular reactivity, JM-1232(-) thus appears safe for neurosurgical patients.
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Affiliation(s)
- Kodai Ikemoto
- Department of Anesthesiology, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo Yamanashi, 409-3898 Japan
| | - Tadahiko Ishiyama
- Surgical Center, University of Yamanashi Hospital, University of Yamanashi, 1110 Shimokato, Chuo Yamanashi, 409-3898 Japan
| | - Noriyuki Shintani
- Department of Anesthesiology, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo Yamanashi, 409-3898 Japan
| | - Nobumasa Asano
- Department of Anesthesiology, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo Yamanashi, 409-3898 Japan
| | - Daniel I Sessler
- Department of Outcomes Research, The Cleveland Clinic, Ohio, USA
| | - Takashi Matsukawa
- Department of Anesthesiology, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo Yamanashi, 409-3898 Japan
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Fukuda M, Vazquez AL, Zong X, Kim SG. Effects of the α₂-adrenergic receptor agonist dexmedetomidine on neural, vascular and BOLD fMRI responses in the somatosensory cortex. Eur J Neurosci 2012; 37:80-95. [PMID: 23106361 DOI: 10.1111/ejn.12024] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 09/19/2012] [Indexed: 01/20/2023]
Abstract
This article describes the effects of dexmedetomidine (DEX) - the active ingredient of medetomidine, which is the latest popular sedative for functional magnetic resonance imaging (fMRI) in rodents - on multiple unit activity, local field potential (LFP), cerebral blood flow (CBF), pial vessel diameter [indicative of cerebral blood volume (CBV)], and blood oxygenation level-dependent (BOLD) fMRI. These measurements were obtained from the rat somatosensory cortex during 10 s of forepaw stimulation. We found that the continuous intravascular systemic infusion of DEX (50 μg/kg/h, doses typically used in fMRI studies) caused epileptic activities, and that supplemental isoflurane (ISO) administration of ~0.3% helped to suppress the development of epileptic activities and maintained robust neuronal and hemodynamic responses for up to 3 h. Supplemental administration of N(2)O in addition to DEX nearly abolished hemodynamic responses even if neuronal activity remained. Under DEX + ISO anesthesia, spike firing rate and the delta power of LFP increased, whereas beta and gamma power decreased, as compared with ISO-only anesthesia. DEX administration caused pial arteries and veins to constrict nearly equally, resulting in decreases in baseline CBF and CBV. Evoked LFP and CBF responses to forepaw stimulation were largest at a frequency of 8-10 Hz, and a non-linear relationship was observed. Similarly, BOLD fMRI responses measured at 9.4 T were largest at a frequency of 10 Hz. Both pial arteries and veins dilated rapidly (artery, 32.2%; vein, 5.8%), and venous diameter returned to baseline slower than arterial diameter. These results will be useful for designing, conducting and interpreting fMRI experiments under DEX sedation.
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Affiliation(s)
- Mitsuhiro Fukuda
- Neuroimaging Laboratory, Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA.
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Asano T, Dohi S, Ohta S, Shimonaka H, Iida H. Antinociception by Epidural and Systemic α2-Adrenoceptor Agonists and Their Binding Affinity in Rat Spinal Cord and Brain. Anesth Analg 2000. [DOI: 10.1213/00000539-200002000-00030] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Ishiyama T, Dohi S, Iida H, Watanabe Y. The Effects of Topical and Intravenous Ropivacaine on Canine Pial Microcirculation. Anesth Analg 1997. [DOI: 10.1213/00000539-199707000-00014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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