Abstract
OBJECTIVE: To investigate the neurotrophic effect of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) in cultured major pelvic ganglia (MPG) derived from young and aged rats. MATERIALS AND METHODS: The dorsocaudal region of the MPG was isolated from 12 6-month-old male rats and 12 24-month-old male rats. The MPGs were treated with BDNF, VEGF, or both, at 0, 12.5, 25, 50, 100 and 150 ng/mL to determine the effective concentration for 50% activity (EC(50)) and optimum dosage for promoting neurite growth. Neurite outgrowth from treated MPGs was measured by microscopy. NADPH diaphorase and tyrosine hydroxylase (TH) staining was used to characterize neurites. RESULTS: Both BDNF and VEGF promoted neurite sprouting from MPG. Neurite growth was more robust in MPGs derived from young rats (6 months) than from aged rats (24 months). The EC(50) for BDNF, VEGF and combined treatment were 10.6, 11.9 and 52 ng/mL in young rats, and 11.3, 12 and 0.75 ng/mL in old rats, respectively. The optimum dosage of both factors for promoting MPG neurite growth in all groups was 25-50 ng/mL. VEGF appeared to favour NADPH diaphorase-positive neurites, whereas BDNF favoured TH-positive neurites. CONCLUSION: BDNF and VEGF promote neurite growth from cultured MPG; combined treatment produced the most robust neurite outgrowth. Neurite growth from MPGs derived from aged rats was not as robust as it was from MPGs from younger rats. Further studies on the effect of neurotrophins after cavernous nerve injury are warranted.