| Backgroud:Parkinson’s disease (PD) is a kind of neurodegenerative disease of central nervous system mainly in the elderly population, the main clinical manifestations characterised by3motor symptoms:resting tremor, bradykinesia and muscle rigidity. There’s still no cure for PD, due to lacking of understanding in its etiology and pathogenesis. So far, nearly all therapies for PD in clinical practice aim to control symptoms and improve motor function, as well as delay time its disability. As the representative of medical therapy, levodopa (L-DOPA) can improve symptoms of PD in earlier stage, but the needs for new intervention are increasing, as the progression of the disease, and the obviously increasing of drug resistance, dyskinesias, and also the appearance of switching phenomena. Deep brain stimulation (DBS) is a type of stereotactic operation, consisting of implanting electrodes into specific brain area of the patient and delivering chronic stimulation to the nuclei, through which the abnormal electrical activities causing clinical symptoms are regulated, resulting in the elimination/improvement of the symptoms and achievement of final purpose of clinical reliefs. Comparing with traditional surgery, high-frequency stimulation of the subthalamic nucleus (STN) alleviates majorities’motor symptoms of advanced PD and has obvious advantages of controllable, reversible, minimally invasive. STN-DBS significantly improves the quality of life for PD patients, serving as a standard technique in treatment of PD and winning high recommendation from neurosurgeons. However, the efficacies of high-frequency stimulation for axial symptoms, such as postural instability, gait disorders are poor, leading to high risk of falling in PD patients, which is one of the major causes for femoral neck fracture, stroke and other serious complications.It is pedunculopontine nucleus (PPN) that located in the border of pontine and middle brain, serving as a major central motor center.Clinical studies suggests that PPN stimulation is effective in improving motor symptoms of advanced PD, in particular, the axial symptoms resistance to STN-DBS. Previous studies have shown that PPN is located in the midbrain involving in the regulation of motor behavior, and PPN neurons of PD undergoing degeneration and apoptosis, with the residual neurons presenting with irregular compensatory abnormal excessive discharge; damaging or low-frequency electrical stimulation of PPN can significantly improve the PD axial symptoms, especially gait resistance to STN-DBS, high-frequency stimulation PPN will only worsen the symptoms, which indicates another mechanism for PPN-DBS different from STN-DBS involved in the regulation of neural circuits. The underlying mechanism of PPN-DBS may affect the spinal cord dorsal root (SGG) to improve PD motor function. Therefore, PPN has become the latest target of DBS for advanced PD. However, the mechanism of PPN-DBS has yet to clarify, the current efficiency of PPN-DBS clinical treatment has yet to be improved, in particular, stimulation parameters pacemaker of PPN-DBS to precisely align the motor symptoms improved has to be elucidated.Animal studies have shown that low-frequency stimulation PPN has approved to improve axial symptoms of advanced PD, but the results are quite different, even contradictory, accounting for a lack of unified quantitative behavior of markers, especially gait aspects of quantitative researches. To this end, it is possible to investigate new reliable behavioral indicators by the Cat Walk automated gait analysis system detecting6-hydroxydopamine (6-OHDA) induced PD model of rats in different periods of changes in the gait and quantitative analysis to explore the quantization of PD gait changes.Objective:1. To explore gait via the Cat Walk automatic gait analysis system in intact rats and the stability and feasibility of the system;2. To investigate gait via the CatWalk automatic gait analysis system in Hemiparkinsonian rats in terms of gait characteristics, characteristics of the optional parameters.Methods:1. CatWalk analysis of intact Wistar rats Behavioral examination of6intact inbred male SPF class Wistar rats was normal, followed by a number of cylinder and CatWalk tests. In order to make sure that the rats can go through CatWalk glass smoothly in the8s pause and not looking back or around, without help of the other stimulation but the food lure stimulus, each rat had to accept the pre-training (the data not for the period statistical analysis). CatWalk test acquisition: CatWalk gait analysis system consisting of a built-in fluorescent glass, a high-frequency camera under the glass bottom and data transmission conversion systems, computer hardware and software components. The testing procedures were as followed:the rats were recorded for at least3times going through the glass smoothly, and each record including at least10steps. When rats successfully went through CatWalk glass, their footprints made glass reflection, and the camera under glass capturing the reflection of the footprints, thus transmitting it to the computer, followed by recording, parallelling offline or online processing. According to the location of each paw marks, size, pressure, and at different time points between the footprints, the CatWalk system calculated both quantitative and qualitative parameters of gait, the static and dynamic characters of gait. This study concerned the original, quantitative footprints indicators of the CatWalk system, including:standing time (s, standing period footprints in contact with the glass of time), standing index (a measure of the speed of the limb away from the glass), the largest contact area (cm2, footprints and glass contact area), the footprints of length (cm, the distance between footprints in the horizontal direction), width (cm, footprints in the vertical direction of the distance), the footprints of area (cm2, footprints in contact with the glass surface area), the maximum pressure (au, the maximum pressure when the footprints with the glass full contact), the minimum pressure (au, minimum footprints and glass contact pressure), the average pressure (au, the average pressure in the footprints with the glass full contact), the maximum pressure in the maximum contact time (au), at maximum contact pressure (au), floating time (s, footprints to leave the glass of the time), vacancies speed (cm/s, footprints in the floating of the speed) walking cycle (s, stance phase and the sum of the vacant period of time) and so on.2. CatWalk analysis of unilateral PD rats18intact inbred male SPF class Wistar rats for behavioral studies with no obvious abnormalities, were randomly divided into6-OHDA group (n=12), sham-operation group (n=6), the use of stereotactic surgery6-OHDA solution and normal saline injected into the left medial longitudinal fasciculus of the6-OHDA and the sham-operation group rats, respectively. At one week preoperatively, training rats and collecting behavioral data at baseline were done, followed by a cylindrical experiment, and then the rat was placed in Catwalk system to record the gait changes at3days,1week and2weeks postoperatively. The collection of CatWalk data were done as descriped previously. After the last test, all the6-OHDA rats,2sham rats underwent immunohistochemisty detection of the substantia nigra-striatal dopamingergic neurons in terms of apotosis. Results:1. CatWalk analysis of intact Wistar rats The parameters of Cat Walk automatic gait analysis system included:the footprints of analysis, Step Sequence, BOS, Print Position, Support, and Phase Dispersions and Couplings. Footprints analysis, qualitative and quantitative analysis; four kinds of step sequence, with AB for Wistar rats; the BOS is divided into forelimb and hind legs; footprints position of the left legs and right legs; phase distribution of the diagonal (right forelimb-left hind, left forelimb-right hind limb), a common side (left hind-right hindlimb, left forelimb-right forelimb) and ipsilateral (right forelimb-right hind limb for the forelimb-left hind leg); links with diagonal (right forelimb-left hind, left forelimb-right hind, right hind-left forelimb), a total of side (left hind-right hindlimb, left forelimb-right foreleg, right hind, left hind limb) and ipsilateral (right forelimb right hind limb, left forelimb-left hind, left hind leg-the left forelimb).2. CatWalk analysis of unilateral PD rats The cylinder test, the postoperative differences in left and right forelimb contrast for rats of6-OHDA were significant (P<0.05), for sham-operated rats not significant (P>0.05). CatWalk analysis showed that:differences in preoperative and postoperative comparisons of left and right limbs for each parameter not statistically significant for the sham-operation group rats (P>0.05).6-OHDA rats the left and right limb contrast, differences in maximum contact area, footprints length, footprints area and footprints width between dual forelimb and max contact area between hind limbs were statistically significant (P<0.05); as for the preoperative and postoperative comparison for each limb, four of the right hind limb decreased, footprints length and footprints width and footprints area of the left forelimb decreased, maximum contact area and footprint length and footprint area of the right forelimb declined, the four parameters in the left hind only footprints width decreased, all the aforementioned differences were statistically significant (P<0.05).Conclusions and discussion:1. The Cat Walk automatic gait analysis system provides multiple perspectives, qualitative and quantitative analysis of the gait of intact rats.2. Not all parameters are appropriate indicators to reflect the PD gait, combined with the characteristics of the laterality of PD rat model, the CatWalk parameters except in the sham operation group to maintain stability, but also meet the following requirements:1.in successful PD model, significant differences in left versus right limb contrast, which is similar to the classic cylinder test;2for preoperative and postoperative comparison of significant differences between the different sides of different limb, that is, the parameters in the contralateral are significantly different, ipsilateral differences, and the lesioned side in the forelimb, hindlimb vary, so it can have a better sensitivity and specificity, thus the quantitative response PD model good behavior in the substantia nigra-striatal dopaminergic neuronal apoptosis. Combined with the results of this study, only the maximum contact area to meet both requirements, that is from the braking phase to the propulsion of a turning point in the contact area of the footprints and glass. The footprints of length, the footprints width and footprints area after two weeks, left versus right front limb comparison were significantly different, coinciding with claim1, consistent with classic cylindrical experimental results. The footprints length and footprints area before the damage to the contralateral limb differences, it seems that the part meets the requirements2, but these two parameters in the damage of the ipsilateral forelimb there are also differences, it is not as first of all indicators. The footprints width not only damage the contralateral forelimb differences can not fully reflect the movement of the contralateral hindlimb; Moreover, the footprints of the width of the damaged ipsilateral limb differences, does not meet the requirements. Comprehensive CatWalk the parameters, the maximum contact area at the same time meet the two requirements mentioned above, patients with PD at the start, turn around, motor symptoms in the complex thinking activities, increase the sense of contact, but the exact mechanism is not clear. In conclusion, the CatWalk is a detection of the rat model of hemiparkinsonism, the maximum contact area as one of the valid parameters for quantitative analysis of PD gait.Full-text summary:CatWalk automatic gait analysis systems has the application of analysis of gait characteristics of intact rats, the system can verify the r qualitative and quantitative determination of gait for Wistar rats. It is applicable to detect changes in gaits of Parkinson’s disease quantitatively, especially in terms of max contact area, adding new tool for further study. |
PDF Full Text Request