OBJECTIVETo observe the correlation between brain-derived neurotrophic factor (BDNF) expression in the nerve system of diabetes mellitus (DM) rats and diabetic erectile dysfunction (ED).

METHODSDM rats were induced by injecting streptozotocin and erectile function test was done by injecting apomorphine (APO) at 1 month, 2 months, 3 months and 4 months. Then the brain, lumbosacral spinal cord, thoracic and lumbar sympathetic trunks, penis and prostate were taken from the diabetic and normal rats of the same age. The BDNF positive neurons and nerve fibers were shown by immunohistochemistry or fluorescence immunohistochemistry. The number and the grey density of BDNF positive cells and fibers were detected by image analysis.

RESULTSCompared with the control group, the erection frequency of the DM rats decreased at 2 months (P <0. 05) , and significantly at 3 and 4 months (P > 0.01) , and the BDNF positive neurons and nerve fibers in the cerebral cortex, lumbosacral spinal cord, thoracic and lumbar sympathetic trunks, penis and prostate of 1-month DM rats were reduced (P <0. 05). As time went on, BDNF declined progressively.

CONCLUSIONBDNF decreases in the central and peripheral nerve system in the early stage of diabetes mellitus, wich is closely correlated with diabetic ED.