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Le TT, Im GH, Lee CH, Choi SH, Kim SG. Mapping cerebral perfusion in mice under various anesthesia levels using highly sensitive BOLD MRI with transient hypoxia. SCIENCE ADVANCES 2024; 10:eadm7605. [PMID: 38416820 PMCID: PMC10901365 DOI: 10.1126/sciadv.adm7605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 01/24/2024] [Indexed: 03/01/2024]
Abstract
Cerebral perfusion is critical for the early detection of neurological diseases and for effectively monitoring disease progression and treatment responses. Mouse models are widely used in brain research, often under anesthesia, which can affect vascular physiology. However, the impact of anesthesia on regional cerebral blood volume and flow in mice has not been thoroughly investigated. In this study, we have developed a whole-brain perfusion MRI approach by using a 5-second nitrogen gas stimulus under inhalational anesthetics to induce transient BOLD dynamic susceptibility contrast (DSC). This method proved to be highly sensitive, repeatable within each imaging session, and across four weekly sessions. Relative cerebral blood volumes measured by BOLD DSC agree well with those by contrast agents. Quantitative cerebral blood volume and flow metrics were successfully measured in mice under dexmedetomidine and various isoflurane doses using both total vasculature-sensitive gradient-echo and microvasculature-sensitive spin-echo BOLD MRI. Dexmedetomidine reduces cerebral perfusion, while isoflurane increases cerebral perfusion in a dose-dependent manner.
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Affiliation(s)
- Thuy Thi Le
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Republic of Korea
| | - Geun Ho Im
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
| | - Chan Hee Lee
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
| | - Sang Han Choi
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Republic of Korea
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Chao THH, Chen JH, Yen CT. Repeated BOLD-fMRI imaging of deep brain stimulation responses in rats. PLoS One 2014; 9:e97305. [PMID: 24825464 PMCID: PMC4019572 DOI: 10.1371/journal.pone.0097305] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2013] [Accepted: 04/17/2014] [Indexed: 11/18/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) provides a picture of the global spatial activation pattern of the brain. Interest is growing regarding the application of fMRI to rodent models to investigate adult brain plasticity. To date, most rodent studies used an electrical forepaw stimulation model to acquire fMRI data, with α-chloralose as the anesthetic. However, α-chloralose is harmful to animals, and not suitable for longitudinal studies. Moreover, peripheral stimulation models enable only a limited number of brain regions to be studied. Processing between peripheral regions and the brain is multisynaptic, and renders interpretation difficult and uncertain. In the present study, we combined the medetomidine-based fMRI protocol (a noninvasive rodent fMRI protocol) with chronic implantation of an MRI-compatible stimulation electrode in the ventroposterior (VP) thalamus to repetitively sample thalamocortical responses in the rat brain. Using this model, we scanned the forebrain responses evoked by the VP stimulation repeatedly of individual rats over 1 week. Cortical BOLD responses were compared between the 2 profiles obtained at day1 and day8. We discovered reproducible frequency- and amplitude-dependent BOLD responses in the ipsilateral somatosensory cortex (S1). The S1 BOLD responses during the 2 sessions were conserved in maximal response amplitude, area size (size ratio from 0.88 to 0.91), and location (overlap ratio from 0.61 to 0.67). The present study provides a long-term chronic brain stimulation protocol for studying the plasticity of specific neural circuits in the rodent brain by BOLD-fMRI.
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Affiliation(s)
| | - Jyh-Horng Chen
- Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chen-Tung Yen
- Department of Life Science, National Taiwan University, Taipei, Taiwan
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Spadavecchia C, Haga H, Ranheim B. Concentration-dependent isoflurane effects on withdrawal reflexes in pigs and the role of the stimulation paradigm. Vet J 2012; 194:375-9. [DOI: 10.1016/j.tvjl.2012.04.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 04/17/2012] [Accepted: 04/18/2012] [Indexed: 10/28/2022]
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Lim DH, Mohajerani MH, Ledue J, Boyd J, Chen S, Murphy TH. In vivo Large-Scale Cortical Mapping Using Channelrhodopsin-2 Stimulation in Transgenic Mice Reveals Asymmetric and Reciprocal Relationships between Cortical Areas. Front Neural Circuits 2012; 6:11. [PMID: 22435052 PMCID: PMC3304170 DOI: 10.3389/fncir.2012.00011] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 02/24/2012] [Indexed: 12/27/2022] Open
Abstract
We have mapped intracortical activity in vivo independent of sensory input using arbitrary point channelrhodopsin-2 (ChR2) stimulation and regional voltage sensitive dye imaging in B6.Cg-Tg (Thy1-COP4/EYFP)18Gfng/J transgenic mice. Photostimulation of subsets of deep layer pyramidal neurons within forelimb, barrel, or visual primary sensory cortex led to downstream cortical maps that were dependent on synaptic transmission and were similar to peripheral sensory stimulation. ChR2-evoked maps confirmed homotopic connections between hemispheres and intracortical sensory and motor cortex connections. This ability of optogentically activated subpopulations of neurons to drive appropriate downstream maps suggests that mechanisms exist to allow prototypical cortical maps to self-assemble from the stimulation of neuronal subsets. Using this principle of map self-assembly, we employed ChR2 point stimulation to map connections between cortical areas that are not selectively activated by peripheral sensory stimulation or behavior. Representing the functional cortical regions as network nodes, we identified asymmetrical connection weights in individual nodes and identified the parietal association area as a network hub. Furthermore, we found that the strength of reciprocal intracortical connections between primary and secondary sensory areas are unequal, with connections from primary to secondary sensory areas being stronger than the reciprocal.
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Affiliation(s)
- Diana H Lim
- Department of Psychiatry, University of British Columbia Vancouver, BC, Canada
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Electroacupuncture analgesia, stress responses, and variations in sensitivity in rats anesthetized with different sub-MAC anesthetics. Eur J Pain 2012; 15:600-7. [DOI: 10.1016/j.ejpain.2010.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 10/08/2010] [Accepted: 11/02/2010] [Indexed: 01/12/2023]
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Jinks SL, Andrada J. Validation and Insights of Anesthetic Action in an Early Vertebrate Network. Anesth Analg 2011; 113:1033-42. [DOI: 10.1213/ane.0b013e3182273c34] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Anesthetic effects on fictive locomotion in the rat isolated spinal cord. Neuroreport 2011; 22:655-9. [PMID: 21817927 DOI: 10.1097/wnr.0b013e32834a20f2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
General anesthetic mechanisms are poorly understood. Anesthetic immobilizing effects occur in the spinal ventral horn. However, a detailed analysis of anesthetic effects on ventral motor networks is lacking. We delivered isoflurane, desflurane, or propofol during NMDA/5-HT-induced, or noxious tail stimulus-evoked, fictive locomotion in neonatal rat isolated spinal cords. Anesthetics changed the frequency, amplitude, and regularity of fictive locomotion with little effect on phase-lag. Isoflurane abolished pharmacologically-induced versus noxious stimulus-induced motor output at similar concentrations. Propofol abolished pharmacologically-induced fictive locomotion through a γ-aminobutyric acid type A-receptor mechanism. Anesthetic effects on pharmacologically-elicted fictive locomotion appear clinically-relevant, and support a ventral horn immobilizing effect on locomotor rhythm generation.
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Spadavecchia C, Levionnois O, Kronen P, Andersen OK. The effects of isoflurane minimum alveolar concentration on withdrawal reflex activity evoked by repeated transcutaneous electrical stimulation in ponies. Vet J 2010; 183:337-44. [DOI: 10.1016/j.tvjl.2008.12.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Revised: 12/22/2008] [Accepted: 12/22/2008] [Indexed: 11/25/2022]
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Anaesthetic mechanisms: update on the challenge of unravelling the mystery of anaesthesia. Eur J Anaesthesiol 2009; 26:807-20. [PMID: 19494779 DOI: 10.1097/eja.0b013e32832d6b0f] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
General anaesthesia is administered each day to thousands of patients worldwide. Although more than 160 years have passed since the first successful public demonstration of anaesthesia, a detailed understanding of the anaesthetic mechanism of action of these drugs is still lacking. An important early observation was the Meyer-Overton correlation, which associated the potency of an anaesthetic with its lipid solubility. This work focuses attention on the lipid membrane as a likely location for anaesthetic action. With the advent of cellular electrophysiology and molecular biology techniques, tools to dissect the components of the lipid membrane have led, in recent years, to the widespread acceptance of proteins, namely receptors and ion channels, as more likely targets for the anaesthetic effect. Yet these accumulated data have not produced a comprehensive explanation for how these drugs produce central nervous system depression. In this review, we follow the story of anaesthesia mechanisms research from its historical roots to the intensely neurophysiological research regarding it today. We will also describe recent findings that identify specific neuroanatomical locations mediating the actions of some anaesthetic agents.
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Masamoto K, Fukuda M, Vazquez A, Kim SG. Dose-dependent effect of isoflurane on neurovascular coupling in rat cerebral cortex. Eur J Neurosci 2009; 30:242-50. [PMID: 19659924 DOI: 10.1111/j.1460-9568.2009.06812.x] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Neurovascular coupling studies are widely conducted in anesthetized animals using functional magnetic resonance imaging (fMRI). In this study, the dose-dependent effects of isoflurane on neurovascular coupling were examined with concurrent recordings of the local field potential (FP) and cerebral blood flow (CBF) in the rat somatosensory cortex. Electrical forepaw stimulation was used, and consisted of either a single pulse or 10 pulses at various frequencies. We observed that the FP response to single-pulse stimulation remained unaffected across the different levels of isoflurane tested (1.1-2.1%), whereas the CBF response to single-pulse stimulation increased dose-dependently (7 +/- 3% to 17 +/- 4%). The isoflurane dose did not affect the vascular reactivity induced by a hypercapnic challenge. These findings suggest that the action of isoflurane affects the neurovascular mechanisms. For 10-pulse stimulation, the summation of the evoked FP responses monotonically decreased with an increase in the isoflurane dose, possibly due to enhancement of the neural adaptation. In contrast, the dose-dependent effect on the CBF response varied with the stimulus frequency; a dose-dependent decrease in the CBF response was observed for high-frequency stimulation, whereas a dose-dependent increase was observed for low-frequency stimulation. Furthermore, a linear time-invariant model consisting of the single-pulse hemodynamic impulse response convoluted with 10-pulse FP recordings showed that the neurovascular transfer function was altered by the isoflurane dose for high-frequency stimulation. These results indicate that careful and consistent maintenance of the depth of anesthesia is required when comparing fMRI data obtained from different animals or physiological and pharmacological manipulations.
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Affiliation(s)
- Kazuto Masamoto
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA 15203, USA
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Barter LS, Mark LO, Antognini JF. Proprioceptive Function Is More Sensitive than Motor Function to Desflurane Anesthesia. Anesth Analg 2009; 108:867-72. [DOI: 10.1213/ane.0b013e318193eabe] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Levionnois OL, Spadavecchia C, Kronen PW, Schatzmann U. Determination of the minimum alveolar concentration of isoflurane in Shetland ponies using constant current or constant voltage electrical stimulation. Vet Anaesth Analg 2009; 36:9-17. [PMID: 19121154 DOI: 10.1111/j.1467-2995.2008.00420.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To determine the minimum alveolar concentration (MAC) of isoflurane in Shetland ponies using a sequence of three different supramaximal noxious stimulations at each tested concentration of isoflurane rather than a single stimulation. STUDY DESIGN Prospective, experimental trial. ANIMALS Seven 4-year-old, gelding Shetland ponies. METHODS The MAC of isoflurane was determined for each pony. Three different modes of electrical stimulation were applied consecutively (2 minute intervals): two using constant voltage (90 V) on the gingiva via needle- (CVneedle) or surface-electrodes (CVsurface) and one using constant current (CC; 40 mA) via surface electrodes applied to the skin over the digital nerve. The ability to clearly interpret the responses as positive, the latency of the evoked responses and the inter-electrode resistance were recorded for each stimulus. RESULTS Individual isoflurane MAC (%) values ranged from 0.60 to 1.17 with a mean (+/-SD) of 0.97 (+/-0.17). The responses were more clearly interpreted with CC, but did not reach statistical significance. The CVsurface mode produced responses with a longer delay. The CVneedle mode was accompanied by variable inter-electrode resistances resulting in uncontrolled stimulus intensity. At 0.9 MAC, the third stimulation induced more positive responses than the first stimulation, independent of the mode of stimulation used. CONCLUSIONS The MAC of isoflurane in the Shetland ponies was lower than expected with considerable variability among individuals. Constant current surface electrode stimulations were the most repeatable. A summation over the sequence of three supramaximal stimulations was observed around 0.9 MAC. CLINICAL RELEVANCE The possibility that Shetland ponies require less isoflurane than horses needs further investigation. Constant current surface-electrode stimulations were the most repeatable. Repetitive supramaximal stimuli may have evoked movements at isoflurane concentrations that provide immobility when single supramaximal stimulation was applied.
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Affiliation(s)
- Olivier L Levionnois
- Department of Clinical Veterinary Sciences, Vetsuisse Faculty, University of Berne, Berne, Switzerland.
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Otto KA. EEG power spectrum analysis for monitoring depth of anaesthesia during experimental surgery. Lab Anim 2008; 42:45-61. [PMID: 18348766 DOI: 10.1258/la.2007.006025] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The first attempts to introduce computerized power spectrum analysis of the electroencephalogram (EEG) as an intraoperative anaesthesia monitoring device started approximately 30 years ago. Since that time, the effects of various anaesthetic agents, sedative and analgesic drugs on the EEG pattern have been addressed in numerous studies in human patients and different animal species. These studies revealed dose-dependent changes in the EEG power spectrum for many intravenous and volatile anaesthetics. Moreover, EEG responses evoked by surgical stimuli during relative light levels of surgical anaesthesia have been classified as 'arousal' and 'paradoxical arousal' reaction, previously referred to as 'desynchronization' and 'synchronization', respectively. Contrasting reports on the correlation between quantitative EEG (QEEG) variables derived from power spectrum analysis (i.e. spectral edge frequency, median frequency) and simultaneously recorded clinical signs such as movement and haemodynamic responses, however, limited the routine use of intraoperative EEG monitoring. In addition, the appearance of EEG burst suppression pattern and isoelectricity at clinically relevant concentrations/doses of newer general anaesthetics (i.e. isoflurane, sevoflurane, propofol) may have weakened the dose-related EEG changes previously reported. Despite these findings, the EEG power spectrum analysis may still provide valuable information during intraoperative monitoring in the individual subject. The information obtained from EEG power spectrum analysis may be further supplemented by newer EEG indices such as bispectral index and approximate entropy or other neurophysiological monitors including auditory evoked potentials or somatosensory evoked potentials.
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Affiliation(s)
- Klaus A Otto
- Institut für Versuchstierkunde und Zentrales Tierlaboratorium, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
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Volatile anesthetic effects on midbrain-elicited locomotion suggest that the locomotor network in the ventral spinal cord is the primary site for immobility. Anesthesiology 2008; 108:1016-24. [PMID: 18497602 DOI: 10.1097/aln.0b013e3181730297] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Volatile anesthetics produce immobility primarily by action in the spinal cord; however, anesthetic effects among different neuronal classes located in different spinal regions, and how they relate to immobility, are not understood. METHODS In decerebrated rats, effects of isoflurane and halothane on movement elicited by electrical microstimulation of the mesencephalic locomotor region (MLR) were assessed in relation to minimum alveolar concentration (MAC). Anesthetic effects on step frequency and isometric limb force were measured. The authors also examined effects of MLR stimulation on responses of nociceptive dorsal horn neurons and limb force responses to tail clamp. RESULTS Mean isoflurane requirements to block MLR-elicited stepping were slightly but significantly greater than MAC by 10%. Mean halothane requirements to block MLR-elicited stepping were greater than those for isoflurane and exceeded MAC by 20%. From 0.4 to 1.3 MAC (but not 0.0 to 0.4 MAC), there was a dose-dependent reduction in the frequency and force of hind limb movements elicited by MLR stimulation during both anesthetics. MLR stimulation inhibited noxious stimulus evoked responses of dorsal horn neurons by approximately 80%. Aptly, MLR stimulation produced analgesia that outlasted the midbrain stimulus by at least 15 s, as indicated by an 81% reduction in hind limb force elicited noxious tail clamp. CONCLUSIONS Because electrical stimulation of the MLR elicits movement independent of dorsal horn activation, the immobilizing properties of isoflurane and halothane are largely independent of action in the dorsal horn. The results suggest that volatile anesthetics produce immobility mainly by action on ventral spinal locomotor networks.
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Trial-by-trial relationship between neural activity, oxygen consumption, and blood flow responses. Neuroimage 2008; 40:442-450. [PMID: 18234525 DOI: 10.1016/j.neuroimage.2007.12.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Revised: 11/02/2007] [Accepted: 12/06/2007] [Indexed: 11/23/2022] Open
Abstract
Trial-by-trial variability in local field potential (LFP), tissue partial pressure of oxygen (PO2), cerebral blood flow (CBF), and deoxyhemoglobin-weighted optical imaging of intrinsic signals (OIS) were tested in the rat somatosensory cortex while fixed electrical forepaw stimulation (1.0-ms pulses with amplitude of 1.2 mA at a frequency of 6 Hz) was repeatedly applied. The changes in the cerebral metabolic rate of oxygen (CMRO2) were also evaluated using a hypotension condition established by our group based on the administration of a vasodilator. Under normal conditions, CBF, PO2, and OIS showed positive signal changes (48%, 32%, and 0.42%, respectively) following stimulation. Over multiple trials, the CBF responses were well correlated with the integral of the LFP amplitudes (sigmaLFP) (Rmean=0.78), whereas a lower correlation was found between PO2 and sigmaLFP (Rmean=0.60) and between OIS and sigmaLFP (Rmean=0.54). Under the hypotension condition the LFP responses were preserved, but the CBF responses were suppressed and the PO2 and OIS changes were negative (-12% and -0.28%, respectively). In this condition, the trial-by-trial variations in PO2 and OIS were well correlated with the variability in sigmaLFPs (Rmean= -0.77 and -0.76, respectively), indicating a single trial coupling between CMRO2 changes and sigmaLFP. These findings show that CBF and CMRO2 signals are more directly correlated with neural activity compared to blood oxygen-sensitive methods such as OIS and BOLD fMRI.
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TAKASUGI Y, FUYUTA M, SUGIURA J, YABUTA K, IWAMOTO T, KOGA Y. The Effect of Sub-MAC Anesthesia and the Radiation Setting on Repeated Tail Flick Testing in Rats. Exp Anim 2008; 57:65-72. [DOI: 10.1538/expanim.57.65] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Affiliation(s)
| | - Masaki FUYUTA
- Department of Anesthesiology, Kinki University School of Medicine
| | - Junko SUGIURA
- Department of Anesthesiology, Kinki University School of Medicine
| | - Koichi YABUTA
- Department of Anesthesiology, Kinki University School of Medicine
| | | | - Yoshihisa KOGA
- Department of Anesthesiology, Kinki University School of Medicine
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Dutton RC, Cuellar JM, Eger EI, Antognini JF, Carstens E. Temporal and Spatial Determinants of Sacral Dorsal Horn Neuronal Windup in Relation to Isoflurane-Induced Immobility. Anesth Analg 2007; 105:1665-74, table of contents. [DOI: 10.1213/01.ane.0000286175.46760.9f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Kushiro T, Wiese AJ, Eppler MC, Muir WW. Effects of perzinfotel on the minimum alveolar concentration of isoflurane in dogs. Am J Vet Res 2007; 68:1294-9. [DOI: 10.2460/ajvr.68.12.1294] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Jinks SL, Carstens EE, Antognini JF. Glutamate receptor blockade in the rostral ventromedial medulla reduces the force of multisegmental motor responses to supramaximal noxious stimuli. Neurosci Lett 2007; 426:175-80. [PMID: 17904740 PMCID: PMC2675539 DOI: 10.1016/j.neulet.2007.08.060] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 08/27/2007] [Accepted: 08/30/2007] [Indexed: 11/27/2022]
Abstract
The rostral ventromedial medulla (RVM) has been established as part of a descending pain-modulatory pathway. While the RVM has been shown to modulate homosegmental nociceptive reflexes such as tail flick or hindpaw withdrawal, it is not known what role the RVM plays in modulating the magnitude of multisegmental, organized motor responses elicited by noxious stimuli. Using local blockade of glutamate receptors with the non-specific glutamate receptor antagonist kynurenate (known to selectively block nociceptive facilitatory ON-cells), we tested the hypothesis that the RVM facilitates the magnitude of multi-limb movements elicited by intense noxious stimuli. In male Sprague-Dawley rats, we determined the minimum alveolar concentration (MAC) of isoflurane necessary to block multi-limb motor responses to noxious tail clamp. MAC was determined so that all animals were anesthetized at an equipotent isoflurane concentration (0.7 MAC). Supramaximal mechanical stimulation of the hindpaw or electrical stimulation of the tail elicited synchronous, repetitive movements in all four limbs that ceased upon, or shortly after (<5 s) termination of the stimulus. Kynurenate microinjection (2 nmol) into the RVM significantly attenuated, by 40-60%, the peak and integrated limb forces elicited by noxious mechanical stimulation of the hindpaw (p<0.001; two-way ANOVA; n=8) or electrical stimulation of the tail (peak force: p<0.011, two-way ANOVA; n=8), with significant recovery 40-60 min following injection. The results suggest that glutamatergic excitation of RVM neurons, presumably ON-cells, facilitates organized, multi-limb escape responses to intense noxious stimuli.
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Affiliation(s)
- Steven L Jinks
- Department of Anesthesiology and Pain Medicine, University of California School of Medicine, Davis, CA 95616, USA.
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Mitsuyo T, Dutton RC, Antognini JF, Carstens E. The differential effects of halothane and isoflurane on windup of dorsal horn neurons selected in unanesthetized decerebrated rats. Anesth Analg 2006; 103:753-60. [PMID: 16931692 DOI: 10.1213/01.ane.0000230605.22930.52] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Halothane and isoflurane, in the peri-minimum alveolar anesthetic concentration (MAC) range, exert differential effects on spinal nociceptive neurons, whereby halothane further depresses their responses from 0.8 to 1.2 MAC, whereas isoflurane does not. We presently investigated if these anesthetics differentially affect windup, the progressive increase in neuronal responses to repetitive noxious stimuli, over a broad concentration range from 0 to 1.2 MAC. In decerebrated rats, single-unit recordings were made from dorsal horn neurons exhibiting windup to 20 1-Hz C-fiber strength electrical stimuli. Halothane and isoflurane (0, 0.4, 0.8, and 1.2 MAC) were tested in a counterbalanced crossover protocol. Increasing halothane and isoflurane from 0 to 1.2 MAC progressively suppressed the response to the first stimulus, as well as summed responses to all stimuli (to 34% +/- 8% and 50% +/- 8%, respectively; P < 0.05). Absolute windup (summed response minus 20x the first response) was suppressed by both anesthetics from 0 to 0.8 MAC, with further depression by halothane but not isoflurane at 1.2 MAC. Responses of neurons isolated at 0 MAC were partially, but never totally, depressed at 0.8 MAC. The dose-dependent suppression of windup is consistent with reduced temporal summation of pain. Further depression at 1.2 MAC halothane, but not isoflurane, suggests different sites of immobilizing action for these two anesthetics. Immobility seems to not be mediated by severe anesthetic depression of a subpopulation of nociceptive neurons.
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Affiliation(s)
- Toshihiko Mitsuyo
- Department of Anesthesiology and Resuscitology, Ehime University Medical School, Matsuyama, Japan
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Abstract
PURPOSE OF REVIEW The concept of minimum alveolar concentration is central to the study of inhalational anesthetics. The minimum alveolar concentration curve is a population concentration-response curve that describes the relationship between anesthetic concentration and oblation of the movement response to painful stimuli. Two features of the minimum alveolar concentration curve, the anesthetic concentration that immobilizes 50% of patients and the steep slope of the curve, may contain useful mechanistic information. There is some dispute, however, about the interpretation of this information. This review examines hypotheses about the shape of the minimum alveolar concentration curve, and recent theoretical and experimental approaches to the question. RECENT FINDINGS The major determining factor for the slope of a quantal, population concentration-response curve is individual variability. The slope of the underlying in-vitro concentration-response curves contributes as well. At the molecular level, in-vitro curves are not steep. The integration of molecular signals that occurs in cells and neuronal circuits can result in steep in-vitro curves, due to multiple molecular targets, amplification and co-operativity. SUMMARY The shape of the minimum alveolar concentration curve has not provided any unambiguous clues about the sites or mechanisms of general anesthesia; however, the universality of anesthetic-induced immobility suggests some future research directions.
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Affiliation(s)
- James P Dilger
- Department of Anesthesiology, Stony Brook University, Stony Brook, New York 11794-8480, USA.
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Spadavecchia C, Levionnois O, Kronen PW, Leandri M, Spadavecchia L, Schatzmann U. Evaluation of administration of isoflurane at approximately the minimum alveolar concentration on depression of a nociceptive withdrawal reflex evoked by transcutaneous electrical stimulation in ponies. Am J Vet Res 2006; 67:762-9. [PMID: 16649907 DOI: 10.2460/ajvr.67.5.762] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate effects of isoflurane at approximately the minimum alveolar concentration (MAC) on the nociceptive withdrawal reflex (NWR) of the forelimb of ponies as a method for quantifying anesthetic potency. ANIMALS 7 healthy adult Shetland ponies. PROCEDURE Individual MAC (iMAC) for isoflurane was determined for each pony. Then, effects of isoflurane administered at 0.85, 0.95, and 1.05 iMAC on the NWR were assessed. At each concentration, the NWR threshold was defined electromyographically for the common digital extensor and deltoid muscles by stimulating the digital nerve; additional electrical stimulations (3, 5, 10, 20, 30, and 40 mA) were delivered, and the evoked activity was recorded and analyzed. After the end of anesthesia, the NWR threshold was assessed in standing ponies. RESULTS Mean +/- SD MAC of isoflurane was 1.0 +/- 0.2%. The NWR thresholds for both muscles increased significantly in a concentration-dependent manner during anesthesia, whereas they decreased in awake ponies. Significantly higher thresholds were found for the deltoid muscle, compared with thresholds for the common digital extensor muscle, in anesthetized ponies. At each iMAC tested, amplitudes of the reflex responses from both muscles increased as stimulus intensities increased from 3 to 40 mA. A concentration-dependent depression of evoked reflexes with reduction in slopes of the stimulus-response functions was detected. CONCLUSIONS AND CLINICAL RELEVANCE Anesthetic-induced changes in sensory-motor processing in ponies anesthetized with isoflurane at concentrations of approximately 1.0 MAC can be detected by assessment of NWR. This method will permit comparison of effects of inhaled anesthetics or anesthetic combinations on spinal processing in equids.
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Affiliation(s)
- Claudia Spadavecchia
- Anesthesiology Section, Department of Clinical Veterinary Sciences, Vetsuisse Faculty, University of Berne, Langassstrasse 124, 3012 Berne, Switzerland
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Cuellar JM, Dutton RC, Antognini JF, Carstens E. Differential effects of halothane and isoflurane on lumbar dorsal horn neuronal windup and excitability. Br J Anaesth 2005; 94:617-25. [PMID: 15734781 DOI: 10.1093/bja/aei107] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Windup of spinal nociceptive neurones may underlie temporal summation of pain, influencing the minimum alveolar concentration (MAC) of anaesthetics required to prevent movement to supramaximal stimuli. We hypothesized that halothane and isoflurane would differentially affect windup of dorsal horn neurones. METHODS We recorded 18 nociceptive dorsal horn neurones exhibiting windup to 1 Hz electrical hindpaw stimuli in rats. Effects of 0.8 and 1.2 MAC isoflurane and halothane were recorded in the same neurones (counterbalanced, crossover design). Windup was calculated as the total number of C-fibre (100-400 ms latency) plus afterdischarge (400-1000 ms latency) spikes/20 stimuli (area under curve, AUC) or absolute windup (C-fibre plus afterdischarge-20 x initial response). RESULTS Increasing isoflurane from 0.8 to 1.2 MAC did not affect AUC, but increased absolute windup from 429 (62) to 618 (84) impulses/20 stimuli (P<0.05) and depressed the initial C-fibre response from 14 (3) to 8 (2) impulses (P<0.05). Increasing halothane from 0.8 to 1.2 MAC depressed AUC from 690 (79) to 537 (65) impulses/20 stimuli (P<0.05) and the initial response from 18 (2) to 13 (2) impulses (P<0.05), but absolute windup was not affected. Absolute windup was 117% greater during 1.2 MAC isoflurane compared with 1.2 MAC halothane. CONCLUSIONS Windup was significantly greater under isoflurane than halothane anaesthesia at 1.2 MAC, whereas the initial C-fibre response was suppressed more by isoflurane. These findings suggest that these two anaesthetics have mechanistically distinct effects on neuronal windup and excitability.
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Jinks SL, Antognini JF, Carstens E. Spectral Analysis of Movement Patterns During Anesthesia. Anesth Analg 2004; 98:698-702, table of contents. [PMID: 14980922 DOI: 10.1213/01.ane.0000100152.31854.2b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED It remains unclear how anesthetics produce immobility, an end-point used in determining anesthetic potency. Understanding how movement (in response to noxious stimulation) is ablated by anesthetics could be aided by using spectral analysis of the high and low frequency components of complex movement patterns. We therefore applied a spectral analysis to previously published movement data from rats anesthetized with isoflurane and halothane at 0.6, 0.9, and 1.1 minimum alveolar concentration (MAC). We recorded isometric forces of hindlimb movement elicited by noxious mechanical stimulation of the hindpaw. The movement patterns were subjected to spectral analysis to determine force amplitude for each frequency component. When halothane was increased from 0.6 to 0.9 MAC, force amplitude decreased only for the lowest-frequency (<1 Hz) components, in part related to the generally lower high-frequency forces at 0.6 MAC. Between 0.6 and 0.9 MAC isoflurane amplitude was reduced for most frequencies in the 0-10 Hz range. For both halothane and isoflurane at 1.1 MAC, as expected, force amplitude substantially decreased at all frequencies. We conclude that spectral analysis is useful to describe and quantify the effects of anesthetics on complex movement patterns resulting from noxious stimuli applied during anesthesia. IMPLICATIONS Complex movement can occur when a noxious stimulus is applied to an anesthetized animal. The frequency components of these movement patterns can be described and quantified by spectral analysis, thus providing a useful tool to investigate the immobilizing properties of anesthetics.
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Affiliation(s)
- Steven L Jinks
- Department of Anesthesiology and Pain Medicine, University of California, Davis, California 95616, USA.
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Affiliation(s)
- Ann E Wagner
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
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Murrell JC, Johnson CB, White KL, Taylor PM, Haberham ZL, Waterman-Pearson AE. Changes in the EEG during castration in horses and ponies anaesthetized with halothane. Vet Anaesth Analg 2003; 30:138-46. [PMID: 14498845 DOI: 10.1046/j.1467-2995.2003.00138.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To identify changes in the amplitude spectrum of the electroencephalogram (EEG) during a standardized surgical model of nociception in horses. ANIMALS Thirteen entire male horses and ponies referred to Division of Clinical Veterinary Science, Bristol (n = 9) and Department of Clinical Veterinary Medicine (n = 4) for castration. MATERIALS AND METHODS Following pre-anaesthetic medication with acepromazine, anaesthesia was induced with guaiphenesin and thiopental and maintained with halothane in oxygen. The EEG was recorded continuously using subcutaneous needle electrodes. Additional monitoring comprised ECG, arterial blood pressure, blood gas analysis, airway gases, and body temperature. All animals were castrated using a closed technique. The raw EEG was analysed after completion of each investigation and the EEG variables median frequency (F50), spectral edge frequency (SEF) 95% and total amplitude were derived from the spectra using standard techniques. The mean values of EEG variables recorded during a baseline time period (recorded before the start of surgery) and castration of each testicle were compared using analysis of variance for repeated measures. RESULTS Total amplitude (Atot) decreased and F50 increased during castration of each testicle compared to the baseline time period [(89.0 +/- 7.8% testicle 1, 87.0 +/- 7.8% testicle 2) and (110.0 +/- 15.0% testicle 1, 109.0 +/- 15.0% testicle 2), respectively]. Changes in SEF 95% were not significant. CONCLUSIONS De-synchronization was identified in the EEG during the nociceptive stimulus of castration. The results suggest that an increase in F50 may be a specific marker for nociception in the horse. CLINICAL RELEVANCE Studies investigating the efficacy of analgesic agents in horses are limited by difficulties in peri-operative pain assessment. This model, using EEG changes associated with nociceptive stimulation, can be used to investigate the anti-nociceptive efficacy of different anaesthetic agents in the horse.
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Affiliation(s)
- Joanna C Murrell
- Department of Clinical Sciences of Companion Animals, University Utrecht, Faculty of Veterinary Medicine, PO Box 80154, NL-3508 TD, Utrecht.
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Antognini JF, Carstens E. In vivo characterization of clinical anaesthesia and its components. Br J Anaesth 2002; 89:156-66. [PMID: 12173227 DOI: 10.1093/bja/aef156] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- J F Antognini
- Department of Anesthesiology, TB-170, University of California at Davis, Davis, CA 95616, USA
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