[Experimental study on the improving effect of motor nerve babysitting on delayed nerve anastomosis]

To observe whether the motor nerve babysitter could improve the delayed nerve anastomosis and promote the functional recovery.

Sixteen SD rats weighing 200-250 g were randomly divided into 2 groups. In group A, the left musculocutaneous nerve was transected to make the model of biceps brachii denervation and anastomosed to its proximal end 6 weeks later; In group B, the musculocutaneous nerve was transected and the distal end was coapted to the purely motor medial pectoral nerve immediately (nerve babysitter) and the musculocutaneous nerve was separated from the medial pectoral nerve, and reanastomosed to its proximal end 6 weeks later. In the animal model, the left limbs served as experimental sides, the right limbs as control sides. After 6 and 12 weeks of the second surgery, behavioral test (grooming test) was performed and the degree of the biceps brachii atrophy was observed, the latent period and the amplitude of the maximum action potentials of the biceps brachii were detected, the wet muscle weight, muscle fiber cross-section area and the activity of Na+-K+-ATPase of the biceps brachii were measured.

After 4 weeks of the second surgery, grooming behavior was found in group B, while few grooming behavior was seen in group A till 6 weeks after the secondary surgery. After 6 weeks of the second surgery, the recovery rate of the latent period and the amplitude, the wet muscle weight, muscle fiber cross-section area and the enzymatic activity of Na+-K+-ATPase of the biceps brachii in group A was 187.25% +/- 1.97%, 46.25% +/- 4.63%, 55.14% +/- 1.99%, 49.97% +/- 1.71%, and 65.81% +/- 2.24%, respectively, which was significantly different from that in group B (155.96% +/- 3.02%, 51.21% +/- 2.13%, 74.18% +/- 1.82%, 55.05% +/- 1.64% and 71.08% +/- 1.53%, respectively, P < 0.05). After 12 weeks of the second surgery, the recovery rate of the latent period and amplitude, the wet muscle weight, muscle fiber cross-section area and the enzymatic activity of Na+-K+-ATPase of the biceps brachii in group A was 145.36% +/- 3.27%, 51.84% +/- 5.02%, 77.92% +/- 1.73%, 61.04% +/- 2.68% and 71.94% +/- 1.65%, respectively, which was significantly different from that in group B (129.83% +/- 8.36%, 75.22% +/- 2.78%, 84.51% +/- 1.34%, 78.75% +/- 3.69% and 84.86% +/- 1.81%, respectively, P < 0.05).

Motor nerve babysitting could reduce muscular damage after denervation, improve the effect of delayed nerve repair and promote the functional recovery of musculocutaneous nerve.