d Original Contribution EFFECTS OF EXTRACORPOREAL SHOCK WAVE THERAPYON FUNCTIONAL RECOVERYAND NEUROTROPHIN-3 EXPRESSION IN THE SPINAL CORD AFTER CRUSHED SCIATIC NERVE INJURY IN RATS JUNG-HO LEE* and SEONG-GIL KIM y *Department of Physical Therapy, School of Medical & Public Health, Kyungdong University, Gangwon-do, Republic of Korea; and y Department of Rehabilitation Science, Daegu University, Gyeongbuk, Republic of Korea (Received 23 May 2014; revised 22 October 2014; in final form 24 October 2014) Abstract—The study described here investigated the effects of extracorporeal shock wave therapy (ESWT) on functional recovery and neurotrophin-3 expression in the spinal cord after sciatic nerve injury in rats. Forty-five 8-wk-old rats were used and randomly divided into three groups: An experimental group, a control group and a sham group. The experimental group received ESWT after the nerve-crushing damage. The sciatic functional index and Dartfish Software were used to determine the effect of sciatic nerve damage on functional changes. A 1-cm length of spinal cord encompassing the L4–6 level was removed for Western blot analysis. The sciatic functional index significantly changed in both the ESWT and control groups after impairment. In the time course evaluation of the ankle angle in the toe off, the ESWT group had statistically significant increases from day 21 onward. There was a significant difference in neurotrophin-3 expression between the groups on days 1, 7 and 14 after impairment. Early application of ESWT increased the expression of neurotrophin-3 and neurotrophin-3 mRNA, and daily therapy facilitated the activity of macrophages and Schwann cells, which affect the survival and regeneration of neurons. (E-mail: Niceguygil@gmail.com) Ó 2015 World Federation for Ultrasound in Medicine & Biology. Key Words: Sciatic nerves, Shock waves, Rehabilitation, Peripheral nerves. INTRODUCTION The peripheral nerve is vulnerable to injury resulting from crushing, stretching, compression and avulsion. Such injury results in severe problems at the level of the spinal cord or dorsal root ganglia (Dahlin 2004). Recovery after the impairment of peripheral nerves tends to be slow and incomplete (Rochkind et al. 2001). The disability in sensory and motor capacity after impairment of peripheral nerves decreases not only the partial or over- all ability of motor nerves, sensory nerves and autonomic nerves, but also quality of life and functional activities (Rosberg et al. 2005). Many studies have investigated the impact of neuro- trophic factors on the maintenance of neurons and regen- eration of axons (Kemp et al. 2011; Markus et al. 2002). After injury, the mature peripheral nerve system exhibits increased production of neurotrophic factors, which facilitate the regeneration of peripheral nerves (Boyd and Gordon 2003; Terenghi 1999). The increase in neurotrophic factors after impairment occurs naturally. An exogenous supply of neurotrophic factors also promotes the regenerative response. The neurotrophic factor neurotrophin-3 (NT-3), which contributes to the survival of neurons, is found in various areas, such as the callosum, hippocampus, cerebral cortex (layer V), primary olfactory cortex, amygdala and spinal cord (Connor and Dragunow 1998). Furthermore, NT-3 con- trols synaptic functions, neuroplasticity and the organiza- tion and development of neurons, not only by stimulating the synthesis of neurotransmitters (Huang and Reichardt 2001), which compensate for the decreased innervation and the decreased number of dendrites after injury, but also by increasing the expression of NT-3 mRNA (Ljungberg et al. 1999; Shimazu et al. 2006; Skaper 2008). The distal part and the myelin of the nerve fibers around the lesion are degraded by Wallerian degenera- tion, and the regression of the proximal part is evidenced by the lesion. Schwann cells in the endoneurium of distal Ultrasound in Med. & Biol., Vol. 41, No. 3, pp. 790–796, 2015 Copyright Ó 2015 World Federation for Ultrasound in Medicine & Biology Printed in the USA. All rights reserved 0301-5629/$ - see front matter http://dx.doi.org/10.1016/j.ultrasmedbio.2014.10.015 Address correspondence to: Seong-Gil Kim, Department of Rehabilitation Science, Daegu University, 15, Jilyang, Gyeongsan-si, Gyeongbuk, Republic of Korea. E-mail: Niceguygil@gmail.com 790