The purpose of this study was to evaluate the influence of the duration of interstitial laser acupuncture therapy effects on neurovegetative and neurobioelectrical parameters like heart rate (HR), heart rate variability (HRV), and electroencephalogram (EEG). We investigated 6 male Sprague-Dawley rats. They underwent 10 min, 20 min, and 30 min interstitial laser acupuncture (in randomized order, with a break of at least 30 min between the different measurement conditions) at the acupoint Neiguan. HR changed significantly only during 20 min red laser stimulation, whereas 10 and 30 min stimulation did not induce significant changes. HRV did not change significantly during any of the different durations; however, an increase was found during 20 min irradiation. Neither the LF/HF ratio of HRV nor the integrated EEG showed significant changes. In this study, it could be experimentally proved that some effects of laser acupuncture are time dependent, and therefore the dosage, as well known from theory, also depends on the time factor. We could especially demonstrate that different treatment times lead to different effects on neurovegetative and neurobioelectrical parameters. Further studies are needed to verify or refute these results.
In a previous study, our research team from China and Austria investigated interstitial (i.st.) laser acupuncture in anesthetized Sprague-Dawley rats for the first time [
Tunér and Hode, both are very renowned researchers on laser therapy, stated in 2010 [
The goal of the present study was to change the dosage of the laser acupuncture treatment via the duration of the i.st. irradiation at the acupoint Neiguan in order to find an optimal treatment time [
Six male healthy Sprague-Dawley rats (weight: 190–300 g) were kept in an animal house maintained at 24 ± 1°C, with a 12-hour light-dark cycle and free access to food and water for seven days before the experiment. The procedure was the same as in our previous work published recently [
The laser needle for i.st. laser irradiation (length: 35 mm; diameter: 0.55 mm) was a Modulas needle (type: IN-Light, Schwa-Medico, Ehringshausen, Germany). It emits red laser light in continuous wave mode with a wavelength of 658 nm and an output power of 50 mW (Figure
Interstitial laser acupuncture in a rat model.
Figure
Experimental procedure for the different durations of i.st. laser acupuncture stimulation.
As in the previous study [
The data were analyzed using Friedman repeated measures analysis of variance (ANOVA) on ranks (SigmaPlot 12.0, Systat Software Inc., Chicago, IL, USA). Post hoc analysis was performed using Holm-Sidak test. The level of significance was defined as
The analysis of the HR of all 6 rats is shown in Figure
Mean heart rate (HR) of the 6 rats. Note the different stimulation durations (10, 20, and 30 min). Significant changes were only found for a duration of 20 min (red line). The error bars indicate the standard error (SE).
In contrast to HR, total HRV increased (insignificantly), also during 20 min laser stimulation. No increases in total HRV were seen during or after 10 min or 30 min laser stimulation (Figure
Changes in total heart rate variability (HRV total) before, during, and after the three stimulation procedures. a.u. (norm): normative arbitrary units. For further explanation, compare with Figure
Figure
LF/HF of the 6 investigated rats. For further explanation, see Figures
Analysis of the bioelectrical brain activity (EEG, Figure
Integrated electrical rat brain activity. Note the (insignificant) increase of the integrated EEG after 20 min laser stimulation. For further explanation, see Figures
Interstitial laser acupuncture is a new acupuncture modality that also allows treatment of different body areas like spinal nerves or joints. The application of laser energy can be performed directly in the region of interest.
In our first animal experimental study, we could demonstrate that there are significant changes in neurovegetative parameters like HR and HRV after i.st. laser stimulation of the left Neiguan acupoint in rats [
In the last years, there was a continuous increase in publications concerning laser acupuncture (see
The term treatment dose is identical to energy density, which is measured in watt seconds per cm² (= joule (J) per cm²). Dosage refers to the amount of energy per unit area brought to bear on tissue or cell culture [
As we have shown in many previous studies, some people can feel the laser, others not [
If we use this formula for our laser acupuncture experiment in rats, the calculated time for effects seen in laser acupuncture is too small (
Although the therapeutic use of laser acupuncture in general is gaining popularity, objective evaluation of the dosage-dependent effects is very difficult [
Our present study is the first one comparing different i.st. laser stimulation treatment times (durations) in rats. It is well known that the effectiveness of laser acupuncture depends upon dosage [
The authors declare that there is no conflict of interests regarding the publication of this paper.
Wei He and Gerhard Litscher contributed equally to this study.
This work was supported by the National Key Basic Research Program 973 (nos. 2011CB505201, 2010CB530507), National Natural Science Foundation of China (81173205), and Beijing Natural Science Foundation (7132148). The scientific investigations were supported by the Stronach Medical Group (Chairman Frank Stronach), the Austrian Federal Ministries of Science and Research and Health, the Eurasia-Pacific Uninet (project “Evidence-based high-tech acupuncture and integrative laser medicine for prevention and early intervention of chronic diseases”), and the German Academy of Acupuncture. The laser stimulation was performed with a Schwa-Medico system from the TCM Research Center Graz at Medical University of Graz, Austria.