Objective: The aims of this study were to measure the normal concentration of nerve growth factor (NGF) in healthy human saliva and to investigate the effects of age and gender differences on saliva NGF level.
Materials and methods: Resting whole, stimulated parotid, and stimulated submandibular/sublingual saliva were collected from 127 healthy volunteers with ages ranging from 20 to 81 years. The saliva NGF concentration was measured by enzyme immunoassay.
Results and conclusions: The mean concentrations of NGF were 901.4 ± 75.6 pg ml−1 in resting whole saliva, 885.9 ± 79.9 pg ml−1 in stimulated parotid saliva, and 1066.1 ± 88.1 pg ml−1 in stimulated submandibular/sublingual saliva. The stimulated submandibular saliva showed lower NGF concentrations with increasing age (ρ = −0.296, P = 0.001). The NGF concentrations of resting whole saliva (P = 0.025) and stimulated parotid saliva (P = 0.005) were significantly higher in women than men. The NGF concentration of stimulated submandibular saliva was significantly higher than stimulated parotid saliva (P = 0.005) and significantly correlated with stimulated parotid saliva NGF level (ρ = −0.244, P = 0.008). We found measurable concentrations of NGF in all three sources of saliva; the concentration was affected by the source for the stimulated parotid and submandibular saliva, age for stimulated submandibular saliva, and gender difference for resting whole saliva and stimulated parotid saliva.