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Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses.

Huang B, Liang F, Zhong L, Lin M, Yang J, Yan L, Xiao J, Xiao Z - Sci Rep (2015)

Bottom Line: Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics.However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses.Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, PR China [2] Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, PR China.

ABSTRACT
Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (∆L and ∆I) were extracted during anesthesia. ∆L and ∆I monitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia, and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ∆L and ∆I. However, ∆L was changed by the hypothermia, whereas ∆I was changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ∆I monitors the anesthesia effect on synapses.

No MeSH data available.


Related in: MedlinePlus

Changes in AEP to 80 dB acoustic stimuli.(a) The records of AEP sampled in 17 sessions lasting 170 min from M20110408 (the acoustic stimuli frequency is 12 kHz.). (b) The L80 and A80 changes extracted from the data shown in Fig. 2a during anesthesia were hereafter labeled as L80- and A80-time curves. (c,d) Summary of L80 and A80 changes (n = 20 mice). (e,f) The normalized L80- and A80-time curves of all mice (n = 20) and the fitting curves to a polynomial regression equation (polynomial order = 4) (blue (R2 = 0.855, intercept = −0.205, B1 = 3.789, B2 = −4.334, B3 = 3.729, B4 = −2.853) and cyan curves (R2 = 0.147, intercept = 0.214, B1 = 1.310, B2 = −2.582, B3 = 4.531, B4 = −3.073)). (g) Comparison between two groups of absolute values of residuals obtained by fitting normalized L80- and A80-time curves (P25 = 0.029, P50 = 0.064, P75 = 0.117, mean = 0.089 and SD = 0.083 for L80; P25 = 0.107, P50 = 0.221, P75 = 0.334, mean = 0.237 and SD = 0.158 for A80; **P < 0.01, 2 Independent Samples Tests).
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f2: Changes in AEP to 80 dB acoustic stimuli.(a) The records of AEP sampled in 17 sessions lasting 170 min from M20110408 (the acoustic stimuli frequency is 12 kHz.). (b) The L80 and A80 changes extracted from the data shown in Fig. 2a during anesthesia were hereafter labeled as L80- and A80-time curves. (c,d) Summary of L80 and A80 changes (n = 20 mice). (e,f) The normalized L80- and A80-time curves of all mice (n = 20) and the fitting curves to a polynomial regression equation (polynomial order = 4) (blue (R2 = 0.855, intercept = −0.205, B1 = 3.789, B2 = −4.334, B3 = 3.729, B4 = −2.853) and cyan curves (R2 = 0.147, intercept = 0.214, B1 = 1.310, B2 = −2.582, B3 = 4.531, B4 = −3.073)). (g) Comparison between two groups of absolute values of residuals obtained by fitting normalized L80- and A80-time curves (P25 = 0.029, P50 = 0.064, P75 = 0.117, mean = 0.089 and SD = 0.083 for L80; P25 = 0.107, P50 = 0.221, P75 = 0.334, mean = 0.237 and SD = 0.158 for A80; **P < 0.01, 2 Independent Samples Tests).

Mentions: Because acoustic stimulus at 80 dB is usually used to collect AEP to reflect the effects of general anesthetics in the clinic313233, we first checked the changes in AEP to 80 dB acoustic stimulus at BF of the recording site during anesthesia. A representative data from the mouse (No. 7, M20110408) to 80 dB acoustic stimuli at BF (12 kHz) showed a total of 17 AEP recording sessions lasted for 170 min after pentobarbital injection (Fig. 2a). In each recording session, ten AEP waveforms (Fig. 2a, the gray lines) were also averaged (Fig. 2a, the red line). Then, the average AEP waveform was used to measure AEP L80 and A80. During anesthesia, the L80 increased and then decreased (Fig. 2b, the red line with triangles to the left ordinate), whereas the A80 first decreased to a plateau and then increased to a maximum and then decreased with some fluctuation (Fig. 2b, the blue line with stars to the right ordinate).


Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses.

Huang B, Liang F, Zhong L, Lin M, Yang J, Yan L, Xiao J, Xiao Z - Sci Rep (2015)

Changes in AEP to 80 dB acoustic stimuli.(a) The records of AEP sampled in 17 sessions lasting 170 min from M20110408 (the acoustic stimuli frequency is 12 kHz.). (b) The L80 and A80 changes extracted from the data shown in Fig. 2a during anesthesia were hereafter labeled as L80- and A80-time curves. (c,d) Summary of L80 and A80 changes (n = 20 mice). (e,f) The normalized L80- and A80-time curves of all mice (n = 20) and the fitting curves to a polynomial regression equation (polynomial order = 4) (blue (R2 = 0.855, intercept = −0.205, B1 = 3.789, B2 = −4.334, B3 = 3.729, B4 = −2.853) and cyan curves (R2 = 0.147, intercept = 0.214, B1 = 1.310, B2 = −2.582, B3 = 4.531, B4 = −3.073)). (g) Comparison between two groups of absolute values of residuals obtained by fitting normalized L80- and A80-time curves (P25 = 0.029, P50 = 0.064, P75 = 0.117, mean = 0.089 and SD = 0.083 for L80; P25 = 0.107, P50 = 0.221, P75 = 0.334, mean = 0.237 and SD = 0.158 for A80; **P < 0.01, 2 Independent Samples Tests).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526847&req=5

f2: Changes in AEP to 80 dB acoustic stimuli.(a) The records of AEP sampled in 17 sessions lasting 170 min from M20110408 (the acoustic stimuli frequency is 12 kHz.). (b) The L80 and A80 changes extracted from the data shown in Fig. 2a during anesthesia were hereafter labeled as L80- and A80-time curves. (c,d) Summary of L80 and A80 changes (n = 20 mice). (e,f) The normalized L80- and A80-time curves of all mice (n = 20) and the fitting curves to a polynomial regression equation (polynomial order = 4) (blue (R2 = 0.855, intercept = −0.205, B1 = 3.789, B2 = −4.334, B3 = 3.729, B4 = −2.853) and cyan curves (R2 = 0.147, intercept = 0.214, B1 = 1.310, B2 = −2.582, B3 = 4.531, B4 = −3.073)). (g) Comparison between two groups of absolute values of residuals obtained by fitting normalized L80- and A80-time curves (P25 = 0.029, P50 = 0.064, P75 = 0.117, mean = 0.089 and SD = 0.083 for L80; P25 = 0.107, P50 = 0.221, P75 = 0.334, mean = 0.237 and SD = 0.158 for A80; **P < 0.01, 2 Independent Samples Tests).
Mentions: Because acoustic stimulus at 80 dB is usually used to collect AEP to reflect the effects of general anesthetics in the clinic313233, we first checked the changes in AEP to 80 dB acoustic stimulus at BF of the recording site during anesthesia. A representative data from the mouse (No. 7, M20110408) to 80 dB acoustic stimuli at BF (12 kHz) showed a total of 17 AEP recording sessions lasted for 170 min after pentobarbital injection (Fig. 2a). In each recording session, ten AEP waveforms (Fig. 2a, the gray lines) were also averaged (Fig. 2a, the red line). Then, the average AEP waveform was used to measure AEP L80 and A80. During anesthesia, the L80 increased and then decreased (Fig. 2b, the red line with triangles to the left ordinate), whereas the A80 first decreased to a plateau and then increased to a maximum and then decreased with some fluctuation (Fig. 2b, the blue line with stars to the right ordinate).

Bottom Line: Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics.However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses.Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, PR China [2] Department of Anesthesiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, PR China.

ABSTRACT
Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it's unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (∆L and ∆I) were extracted during anesthesia. ∆L and ∆I monitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia, and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ∆L and ∆I. However, ∆L was changed by the hypothermia, whereas ∆I was changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ∆I monitors the anesthesia effect on synapses.

No MeSH data available.


Related in: MedlinePlus