Peripheral BDNF Regulates Somatosensory-Sympathetic Coupling in Brachial Plexus Avulsion-Induced Neuropathic Pain / 神经科学通报·英文版

Brachial plexus avulsion (BPA) is a combined injury involving the central and peripheral nervous systems. Patients with BPA often experience severe neuropathic pain (NP) in the affected limb. NP is insensitive to the existing treatments, which makes it a challenge to researchers and clinicians. Accumulated evidence shows that a BPA-induced pain state is often accompanied by sympathetic nervous dysfunction, which suggests that the excitation state of the sympathetic nervous system is correlated with the existence of NP. However, the mechanism of how somatosensory neural crosstalk with the sympathetic nerve at the peripheral level remains unclear. In this study, through using a novel BPA C7 root avulsion mouse model, we found that the expression of BDNF and its receptor TrκB in the DRGs of the BPA mice increased, and the markers of sympathetic nervous system activity including α1 and α2 adrenergic receptors (α1-AR and α2-AR) also increased after BPA. The phenomenon of superexcitation of the sympathetic nervous system, including hypothermia and edema of the affected extremity, was also observed in BPA mice by using CatWalk gait analysis, an infrared thermometer, and an edema evaluation. Genetic knockdown of BDNF in DRGs not only reversed the mechanical allodynia but also alleviated the hypothermia and edema of the affected extremity in BPA mice. Further, intraperitoneal injection of adrenergic receptor inhibitors decreased neuronal excitability in patch clamp recording and reversed the mechanical allodynia of BPA mice. In another branch experiment, we also found the elevated expression of BDNF, TrκB, TH, α1-AR, and α2-AR in DRG tissues from BPA patients compared with normal human DRGs through western blot and immunohistochemistry. Our results revealed that peripheral BDNF is a key molecule in the regulation of somatosensory-sympathetic coupling in BPA-induced NP. This study also opens a novel analgesic target (BDNF) in the treatment of this pain with fewer complications, which has great potential for clinical transformation.

Free perforating flap of peroneal artery for repairing the forefoot skin defects / 中国骨伤

<p><b>OBJECTIVE</b>To explore the clinical techniques and effects of repairing skin defects of the forefoot by free perforating flap nourished by peroneal artery.</p><p><b>METHODS</b>From June 2007 to June 2011, 11 patients with skin and soft tissue defects of the forefoot were repaired by free peroneal artery perforating flap in emergent or subemergent. There were 10 males and 1 female with an average age of 28.6 years old ranging from 23 to 46 years old. Among them, 4 cases injured for traffic accidents, 3 for crush and 4 for machine strangulation. In all cases, the defect area of forefoot tissue varied from 2.0 cm x 4.0 cm to 4.0 cm x 8.5 cm,and the adopted area varied from 2.5 cm x 4.5 cm to 4.0 cm x 9.0 cm. The operation time was from 6 to 96 h (averaged 31.8 h). The blood vessels were anastomosed end-to-end.</p><p><b>RESULTS</b>All of the transferred free flaps survived uneventfully. Nine of them were successfully followed up from 6 to 24 months. The appearance, elasticity and functions of flaps were satisfied accompanied with slight damage of donor site although seemed bloated. The smaller donor site could be intimately seamed if necessary.</p><p><b>CONCLUSION</b>The vessels anatomy of knee with antegrade extended peroneal artery was relative constant with a moderate thickness and simple operation, is useful to repair small or middle areas of skin defects in forefoot.</p>