Increased Calcitonin Gene-Related Peptide and Macrophages Are Involved in Astragalus membranaceus-Mediated Peripheral Nerve Regeneration in Rats

• Published in: The American journal of Chinese medicine (1979) Vol. 46; no. 1; p. 69
• Main Authors: Chen, Chung-Chia, Chang, Ling-Chuan, Yao, Chun-Hsu, Hsu, Yuan-Man, Lin, Jia-Horng, Yang, Tse-Yen, Chen, Yung-Hsiang, Chen, Yueh-Sheng
• Format: Journal Article
• Language: English
• Published: Singapore 2018
• Subjects: Calcitonin Gene-Related Peptide; Chinese Herbal Medicine; Peripheral Nerve Regeneration; Astragalus membranaceus; Macrophage
• ISSN: 0192-415X; 1793-6853
• DOI: 10.1142/S0192415X18500040

Astragalus membranaceus (AM) is one of 50 fundamental herbs in traditional Chinese medicine. Previous studies have shown that AM extract can be a potential nerve growth-promoting factor, being beneficial for the growth of peripheral nerve axons. We further investigated the effects of AM extract on regeneration in a rat sciatic nerve transection model. Rats were divided into three groups ([Formula: see text]): normal saline (intraperitoneal) as the control, and 1.5[Formula: see text]g/kg or 3.0[Formula: see text]g/kg of AM extract (every other day for four weeks), respectively. We evaluated neuronal electrophysiology, neuronal connectivity, macrophage infiltration, expression levels and location of calcitonin gene-related peptide (CGRP), and expression levels of both nerve growth factors (NGFs) and immunoregulatory factors. In the high-dose AM group, neuronal electrophysiological function (measured by nerve conductive velocity and its latency) was significantly improved ([Formula: see text]). Expression levels of CGRP and macrophage density were also drastically enhanced ([Formula: see text]). Expression levels of fibroblast growth factor (FGF), NGF, platelet-derived growth factor (PDGF), transforming growth factor-[Formula: see text], interleukin-1 (IL-1), and interferon (IFN)-[Formula: see text] were reduced in the high-dose AM group ([Formula: see text]), while FGF, NGF, PDGF, IL-1, and IFN-[Formula: see text] were increased in the low-dose AM group ([Formula: see text]). These results suggest that AM can modulate local inflammatory conditions, enhance nerve regeneration, and potentially increase recovery of a severe peripheral nerve injury.