Abstract:

BACKGROUND: There were disadvantages of animal models in the study of the relationship of muscle and skeleton. Recent study has been demonstrated the effect of Botulinum toxin type A to atrophy local muscle without influencing the surrounding muscle.
OBJECTIVE: To construct a reasonable animal model of local muscle atrophy by local injection of Botulinum toxin type A.
METHODS: Totally 25 male Wistar rats of 4 months were subjected to ketamine (0.2 mL/kg) and Sumianxin (0.2 mL/kg) by intramuscular injection. A 0.5-cm incision was made on the middle of dorsal femur to expose quadriceps femoris. Right quadriceps femoris was injected with 2 Units (0.2 mL) of Botulinum toxin type A, and left quadriceps femoris of the same rat with the same amount of saline as controls. At 1, 2, 4, 6, 8 weeks after injection, 5 rats were used to take gross observation and histological examination.
RESULTS AND CONCLUSION: Gross observation of the muscle tissue showed that, compared with self-controlled group, the volume and weight of the quadriceps femoris were decreased significantly (P < 0.01). The histological examination of muscle tissue showed the atrophy of the quadriceps femoris from experimental group was more obvious, the muscle fiber become thin, and the nuclei of the muscle fiber assemble together, with small distance between muscle fibers. Weight of the quadriceps femoris treated with Botulinum toxin type A was decreased at 1 and 2 weeks. The increase in weight of muscle was slow among muscle at 4, 6 and 8 weeks. The muscle weight showed an increased tendency in the saline side at various time points. Injecting Botulinum toxin type A into local muscle is a reasonable way to set up an experimental model of the atrophy of a destination muscle with strong practice, good repeatability, high stability, and may be used to examine the relationship of muscle and skeleton.