Objective To observe the expression of autophagy-related genes and proteins in the smooth bladder muscle of rats after spinal cord injury (SPI).Methods Twenty-four male Wistar rats were randomly and evenly divided into a model group and a control group.The model group had SPI induced using the modified Allen's method,while the control group was only given laminectomy.Six hours after the operation,the Basso Beattle Bresnahan (BBB) locomotor rating scale was used to evaluate the rats' hindlimb locomotor function.Nissl staining was used to observe the morphological changes in their spinal cords,while Western blotting and immunofluorescence staining were employed to assess the expression of microtubule-associated protein 1 light chain 3 (LC3) and protein 62 (P62).The expression of autography gene Beclin1 mRNA was determined using a reverse transcription polymerase chain reaction (RT-PCR).Results The average BBB score in the model group was significantly lower than in the control group.After Nissl's staining,a decreased number of neurons and Nissl bodies was observed.Western blotting showed that the expression of LC3-Ⅱ had increased significantly and that of P62 had decreased significantly in the model group compared with the control group.The immunofluorescence staining showed LC3 and P62 dots in the bladders' smooth muscle cells.RT-PCR detected significantly higher LC3 and Beclinl mRNA levels in the model group than in the control group;in contrast the average P62 mRNA level was significantly lower.Conclusions Autophagy was activated in rats' bladder muscles after SPI.That may be related to the pathogenesis of a neurogenic bladder after spinal cord injury.