NGF and obstructive sleep apnea syndrome: Meanwhile, the protein expressions of NGF (0.19 ± 0.02 vs. 0.69 ± 0.05, P = 0.0001), c-Fos (0.17 ± 0.01 vs. 0.41 ± 0.07, P = 0.0043), and PGP9.5 (0.18 ± 0.05 vs. 0.63 ± 0.08, P = 0.0015) were significantly upregulated in the OSA group compared with the control group in the LSG (Fig 8E–8H), no significant changes were observed in the LVN (all P value >0.05) (Fig 8I–8L).