A combination of drugs, electrical stimulation and treadmill exercises was used to reawaken 'walking circuits' in the spinal cords of paralysed rats

    People who are left wheelchair-bound by spinal cord injuries could regain some of their mobility through a rehabilitation programme being developed by scientists. Guardian neuroscience stories have found that a combination of drugs, muscle stimulation and treadmill exercises helps paralysed rats to recover the ability to walk normally.

    The animal tests pave the way for clinical trials in humans, which scientists hope to begin in the US and Switzerland within five years.

    The treatment, developed by neurologists at the University of Zurich and the University of California in Los Angeles, taps into neural circuits in the spinal cord that control the muscles used for walking.

    In able-bodied people, these "walking circuits" spring into action when they receive a signal from the brain, but if the spinal cord is damaged, the message from the brain never arrives. When contact with the brain is lost, the circuits shut down.

    "We've known for more than a century that there are networks of neurons in the spinal cord that generate the rhythmic activity needed for walking," said Grégoire Courtine at the Experimental Neurorehabilitation laboratory in Zurich. "Our study suggests that the brain mostly sends a go or no-go signal."

    A team led by Courtine used drugs known as serotonin agonists to awaken the walking circuits in paralysed rats whose spines had been severed. The researchers then used tiny electrodes to stimulate the animals' spinal circuitry, according to a report in the journal Nature Neuroscience.

    During the eight-week study, the rats spent 20 minutes a day walking on a treadmill. At first they were unable to move their hind legs at all, but by the end of the study they could support their weight and walk almost perfectly. Although the rats had regained the ability to walk, they were still reliant on an electrical wire to switch their movements on and off.

    Courtine said the group is eager to begin human trials, but first needs to develop implantable electrodes to stimulate the walking circuits in patients' spines.

    "With a neuroprosthesis, we could get some improvement in function in patients with severe spinal cord injuries," he said. "The majority of patients have some intact spinal nerves that give them a limited ability to move their muscles. For these patients, our intervention could be extremely beneficial."

    以老鼠為實驗對象的研究發現，藥物、電刺激與鍛煉相結合的組合療法，有助于喚醒癱瘓老鼠脊髓中受損的行走神經回路；這為癱瘓病人帶來了新希望。

    因脊髓損傷而坐輪椅的癱瘓病人可以通過科學家開發的一種康復方案重新獲得一定程度的行動能力。《衛報》神經學欄目的報道新聞發現，聯合使用藥物、肌肉刺激及跑步機練習可以幫助癱瘓的老鼠重新恢復正常行走的能力。

    動物實驗的成功為相應的人類臨床試驗鋪平了道路，科學家希望在五年內從美國和瑞士開始這種臨床試驗。

    由蘇黎世大學和加州大學洛杉磯分校的神經學專家開發的這種療法所利用的就是脊髓中控制步行所用肌肉的神經回路。

    對于健康的人來說，這些"行走回路"一旦收到大腦發出的信號之后，便迅速行動。但如果脊髓受到破壞，它們便無法獲得大腦發出的訊息。當與大腦失去了聯系，這些神經回路便會關閉。

    "脊髓中含有產生行走所需節奏性活動的神經元網絡，這一點早在一個多世紀前就為人所知了，"蘇黎世實驗神經康復實驗室（Experimental Neurorehabilitation laboratory）的格雷瓜爾·庫爾蒂納（Grégoire Courtine）說，"我們的研究表明，大腦主要發送的是一個走或不走的信號。"

    據刊登在《自然-神經學》（Nature Neuroscience）雜志上的一份報告所述，由庫爾蒂納帶領的研究小組對脊髓完全受損的癱瘓老鼠進行了實驗，實驗中采用叫做血清素致效劑（serotonin agonist）的藥物，來喚醒癱瘓老鼠的步行回路。接著，研究人員利用微型電極來刺激老鼠的脊髓回路。

    在為期8周的研究中，老鼠每天在跑步機上行走20分鐘。起初，它們根本無法移動后腿，但在研究結束時，這些老鼠可以承擔全身的重量，而且可以近乎完美地步行。雖然這些老鼠已恢復了行走能力，但是，它們仍需依靠一根電線來帶動自己行走及停止。

    庫爾蒂納表示，該研究小組迫切希望開始人體試驗，但首先需要開發便于刺激患者脊椎中步行回路的植入式電極。

    "通過神經假體（neuroprosthesis）,我們可以使脊髓嚴重損傷的患者獲得一些功能性改善，"他說，"大部分患者還有一些完好的脊髓神經，可以讓他們能在有限范圍內運用肌肉。對于這些患者來說，我們的療法可能極有裨益。"