Huo Xiaolin

The effects of chronic repetitive transcranial magnetic stimulation on glutamate and gamma-aminobutyric acid in rat brain

Recent studies have shown that repetitive transcranial magnetic stimulation (rTMS) has therapeutic potential for some neurological and psychiatric disorders. However, the neurobiological effects of this tool are not sufficiently explained so far, previous research reported that rTMS can change dopamine release, there have been few studies to examine a possible effect of rTMS on amino acid neurotransmitter. This study aimed to determine the effects of chronic rTMS on glutamate and gamma-aminobutyric acid concentration in the rat brain. Sprague–Dawley rat was subject to 500 pulses of 0.5 Hz rTMS for 15 days, or sham stimulation. After last stimulation, glutamate and gamma-aminobutyric acid content were measured by high performance liquid chromatography (HPLC). Results showed that the content of glutamate and gamma-aminobutyric acid increased significantly in hippocampus and striatum after chronic rTMS, but reduced significantly in the hypothalamus. These results indicate that chronic rTMS has a modulatory effect on the glutamate and gamma-aminobutyric acid systems. This change in amino acid neurotransmitter may contribute to its beneficial effects.

Effects of extremely low-frequency-pulsed electromagnetic field on different-derived osteoblast-like cells.

The aim of this study is to investigate the effects of extremely low-frequency pulsed electromagnetic field (PEMF) on osteoblast-like cells. PEMF with a magnetic flux density of 1.55 mT at 48 Hz was employed to stimulate the MC3T3-E1 cell and the primary osteoblast cell derived from 2-day-old Sprague Dawley (SD) rat calvaria for different time. MTS method was applied to analyze cell proliferation and flow cytometry to detect cell cycle. The intracellular alkaline phosphatase (ALP) activity was measured by colorimetry. Our results demonstrated that PEMF of 1.55 mT at 48 Hz did not affect cell number of MC3T3-E1 cell, whereas the cell percentage of S and G2M phase decreased significantly. Although the cell number of the primary osteoblast cell did not alter by MTS assay after being exposed to PEMF for 24 h continuously, the cell percentage of S and G2M phase increased significantly. When culture time extended to 48 h, the cell number increased greatly and the cell percentage of S and G2M phase decreased significantly despite of the exposure type. After the primary osteoblast cell was exposed to PEMF for 24 h continuously, the ALP activity decreased significantly, whereas it increased significantly when being exposed to PEMF for 48 h continuously. From the results we concluded that PEMF of 1.55 mT at 48 Hz did not affect proliferation and differentiation of MC3T3-E1 cell, but it promoted proliferation, inhibited differentiation at proliferation stage, and promoted differentiation at differentiation stage of primary osteoblast cells.

A model of injury potential for myelinated nerve fiber

Excellent models have been described in literatures which related membrane potential to extracellular electric or magnetic stimulation and which described the formation and propagation of action potentials along the axon, for both myelinated and nonmyelinated fibers. There is not, however, an adequate model for nerve injury which allows to compute the distribution of injury potential, a direct current potential difference between intact and injured nerve, because its importance has been ignored in the shadow of the well-known action potential. This paper focus on the injury potential and presents a model of the electrical properties of myelinated nerve which describes the time course of events following injury. The time-varying current and potential at all nodes can be computed from the model, and the factors relate to the amplitude of injury potential can be determined. It is shown that the amplitude of injury potential decreased gradually with injury time, and the recession curve was exponential. Results also showed that the initial amplitude of injury potential is positively related to the grade of injury and fiber diameter. This model explained the mechanism of formation of injury potential and can provide instruction for applied electric field to prevent the formation injury potential.

Influence of low-frequency rTMS on EEG of epileptic rats

The present research was to study the influence of low-frequency rTMS on epilepsy by EEG analysis. A train of 100, 0.5 Hz rTMS was applied on 15 Sprague-Dawley rats, and sham stimulation was also applied. EEG was recorded before stimulation and within 1 minute after rTMS and sham stimulation. Results showed that mean absolute power (MAP) of gamma band and relative power (RP) of beta and gamma band decreased significantly after low-frequency rTMS. In another experiment, pentylenetetrazol was injected immediately after 100 impulses of 0.5 Hz rTMS. Results showed that seizure susceptibility decreased greatly. These results indicate that low-frequency rTMS has certain suppressive effects on epilepsy due to power spectrum reduction.