Ian Hsiao

Peripheral nerve grafts and aFGF restore partial hindlimb function in adult paraplegic rats

The purpose of this study was to evaluate the degree of functional recovery in adult rats with completely transected spinal cord following experimental treatment regimens that include implantation of peripheral nerve segments and local application of acidic fibroblast growth factor (aFGF). Rats were randomly divided to five groups: (1) spinal cord transection, (2) spinal cord transection and aFGF treatment, (3) spinal cord transection and peripheral nerve grafts, (4) spinal cord transection, aFGF treatment, and peripheral nerve grafts, and (5) sham control (laminectomy only). The locomotor behavior of all rats was analyzed by the Basso, Beattie and Bresnahan (BBB) open field locomotor test over the six months survival time. Immunohistochemisty for neurofilament protein, and somatosensory (SSEP) and motor evoked potentials (MEP) were used to evaluate axon growth across the damage site following the different treatments. The results show four principal findings: (1) Only the combination of peripheral nerve grafts and aFGF treatment improved hindlimb locomotor function after spinal cord transection. (2) The SSEP and MEP demonstrated electrophysiological evidence of both sensory and motor information crossing the damaged site, but only in the combined nerve grafts and aFGF treatment rats. (3) Immunostaining demonstrated neurofilament positive axons extending through the graft area and into distal end of spinal cord, but only in the group with combined nerve grafts and aFGF treatment. (4) Retransection of group 4 rats eliminated the behavioral recovery, MEP, and SSEP responses, indicating that the improvement of hindlimb locomotor activity came from supraspinal control. These results demonstrate the ability of the repair strategy combining peripheral nerve grafts and aFGF treatment to facilitate the regeneration of spinal ascending and descending tracts and also recovery of motor behavior following spinal cord injury.

High intensity magnetic stimulation over the lumbosacral spine evokes antinociception in rats

OBJECTIVES High intensity magnetic stimulation (MS) applied over the skin can painlessly depolarize superficial and deep nerves and we aimed to evaluate the effectiveness of MS of spinal nerves in evoking a potent analgesic response. METHODS The MS was administered to adult male Sprague-Dawley rats using a Cadwell MES-10 high-speed magnetic stimulator. A Peltier device and von Frey fibers were used to determine heat and mechanical nociceptive responses of the rats. RESULTS A brief (5 min) course of MS over the rats lumbosacral spine produced a long-lasting (30-40 min) and robust (80-90% maximum possible effect) hindpaw antinociceptive effect to both mechanical and heat stimuli. Spinal cord transected rats had intact hindpaw nociceptive withdrawal responses, but transection eliminated MS evoked antinociception, indicating a critical extrasegmental component in the mechanism of MS antinociceptive action. The opiate receptor antagonist naloxone (5 mg/kg, i.p.) completely blocked MS evoked antinociception, demonstrating an opioidergic mechanism for MS antinociception. The alpha(2) adrenoceptor antagonist atipamezole (5 mg/kg, i.p.) slightly reduced the MS antinociceptive response to heat and had no effect on MS antinociception for mechanical stimuli. CONCLUSIONS These data indicate that MS can evoke a robust, long-lasting antinociceptive effect, which requires an intact supraspinal pathway and is opioidergic mediated.

Re-growth of catecholaminergic fibers and protection of cholinergic spinal cord neurons in spinal repaired rats

The extent of re‐growth of catecholaminergic fibers, the survival of cholinergic neurons and the degree of autonomic dysreflexia were assessed in complete spinal cord‐transected adult rats that received a repair treatment of peripheral nerve grafts and acidic fibroblast growth factor (aFGF). The rats were randomly divided into three groups: (1) sham control group (laminectomy only); (2) spinal cord transection at T8 (transected group); and (3) spinal cord transection at T8, followed by aFGF treatment and peripheral nerve graft (repaired group). The spinal cords and brains of all rats were collected at 6 months post‐surgery. Immunohistochemistry for tyrosine hydroxylase (TH) and dopamine‐β‐hydroxylase (DBH), and fluoro‐gold (FG) retrograde tracing were used to evaluate axon growth across the damage site, and immunocytochemistry for choline acetyl transferase (ChAT) was used to evaluate cholinergic neuronal cell survival following the injury and treatment. When comparing with the transected group, the repaired group showed: (1) lower elevation of mean arterial pressure during colorectal distension; (2) retrogradely labeled neurons in the hypothalamus, zona incerta, subcoeruleus nuclei and rostral ventrolateral medulla following application of FG below the repair site; (3) the presence of TH‐ and DBH‐labeled axons below the lesion site; (4) higher numbers of ChAT‐positive neurons in ventral horn and intermediolateral column near the lesion site. We conclude that peripheral nerve graft and aFGF treatments facilitate the re‐growth of catecholaminergic fibers, also protect sympathetic preganglionic neurons and spinal motor neurons, and reduce autonomic dysfunction in a T‐8 spinal cord‐transected rat model.

Improvement of gait patterns in step-trained, complete spinal cord-transected rats treated with a peripheral nerve graft and acidic fibroblast growth factor

The effects of peripheral nerve grafts (PNG) and acidic fibroblast growth factor (alpha FGF) combined with step training on the locomotor performance of complete spinal cord-transected (ST, T8) adult rats were studied. Rats were assigned randomly to five groups (N=10 per group): sham control (laminectomy only), ST only, ST-step-trained, repaired (ST with PNG and alpha FGF treatment), or repaired-step-trained. Step-trained rats were stepped bipedally on a treadmill 20 min/day, 5 days/week for 6 months. Bipolar intramuscular EMG electrodes were implanted in the soleus and tibialis anterior (TA) muscles of ST-step-trained (n=3) and repaired-step-trained (n=2) rats. Gait analysis was conducted at 3 and 6 months after surgery. Stepping analysis was completed on the best continuous 10-s period of stepping performed in a 2-min trial. Significantly better stepping (number of steps, stance duration, swing duration, maximum step length, and maximum step height) was observed in the repaired and repaired-step-trained than in the ST and ST-step-trained rats. Mean EMG amplitudes in both the soleus and TA were significantly higher and the patterns of activation of flexors and extensors more reciprocal in the repaired-step-trained than ST-step-trained rats. 5-HT fibers were present in the lumbar area of repaired but not ST rats. Thus, PNG plus alpha FGF treatment resulted in a clear improvement in locomotor performance with or without step training. Furthermore, the number of 5-HT fibers observed below the lesion was related directly to stepping performance. These observations indicate that the improved stepping performance in Repaired rats may be due to newly formed supraspinal control via regeneration.

Functional magnetic stimulation facilitates gastrointestinal transit of liquids in rats

The purpose of this study was to investigate the effect of a relatively novel technology, functional magnetic stimulation (FMS), on gastrointestinal transit of liquids in rats. Orogastric gavage with technetium‐99 solution was used to assess gastric emptying and gastrointestinal transit time in 92 rats. FMS was performed over the anterior cervical and/or dorsal thoracolumbar regions using a figure‐8 coil. Stimulation protocols were 1, 2, or 4 h in length. FMS accelerated gastric emptying and decreased gastrointestinal transit time. The acceleration was dependent on the stimulation parameters used as well as on the duration of the protocol; high levels of FMS produced a quicker effect, whereas lower levels were effective at later times. This study provides evidence that FMS could be an alternative or adjunct therapy to treat disorders in gastrointestinal motility.