Study on relationship between genetic expression of BDNF and NRG-1 and myelinated nerve fiber density and cross-sectional area in thoracic sympathetic trunk of palmar hyperhidrosis

Abstract

Objective To investigate the gene expression of brain-derived neurotrophic factor ( BD-NF) and neuregulin-1 (NRG-1) in thoracic sympathetic trunk and their relation to myelinated nerve fiber density and single myelinated nerve fibers cross-sectional area in palmar hyperhidrosis. Methods Fast red-fast green myelin sheath staining was used to show myelinated nerve fibers. Using the micro-image analysis system,30 cases of myelinated nerve fiber density and single myelinated nerve fibers cross-sectional area were observed in T3 thoracic sympathetic trunk of patients with palmar hyperhidrosis. BDNF and NRG-1 gene expression was also analyzed by RT-PCR. Eight cases of non-palmar hyperhidrosis patients served as controls. Results In 33 thoracic sympathetic trunk of patients with palmar hyperhidrosis, myelinated nerve fiber density and single myelinated nerve fibers cross-sectional area were significantly increased as compared with controls (t = 7. 023,P < 0.05 ; t = 7.462, P < 0.05 respectively). The expression of BDNF and NRG-1 in 33 thoracic sympathetic trunk of patients with palmar hyperhidrosis was 1. 176 00 ± 0.028 70,1. 216 10± 0.075 39 respectively, and that in control group was 1. 037 50 ± 0.053 79,1. 042 70 ± 0.043 57 respectively. The former was significantly higher than the latter ( t = 9.940,P < 0.05 ; t = 6. 195. P < 0.05 respectively). Conclusion BDNF and NRG-I gene over expression increased myelinated nerve fiber density and single myelinated nerve fibers cross-sectional area of thoracic sympathetic trunk in patients with palmar hyperhidro-sis. Thus transmission speed and ability of excitatory of thoracic sympathetic nerve were also increased, which may play a role in the pathogenesis of palmar hyperhidrosis. Key words: Palmar hyperhidrosis ; Thoracic sympathetic trunk ; NRG-1 ; BDNF