| Background and ObjectiveNerve regeneration and functional recovery after peripheral nerve injury have been hotspots of clinical research. Nerve anastomosis technique afte nerve rupture is improving day by day, while the functional recovery has been less than satisfactory. Therefore, many academics and clinicians have been seeking an effective solution. In order to solve the functional problem, we must first solve the problem of nerve regeneration. There is no denying that the nerve regeneration process is closely related to the extension of axons and myelin, but cytoskeleton reconstruction of the growth cone in is closely related to the neurite extension. The main components of the cytoskeleton are microtubules, microfilaments and neurofilament proteins. The content of these proteins and regenerative axon myelination, and neurotrophic factors as hormones, Schwann cells, macrophages, cell matrix and adhesion molecules in the microenvironment of the regenerating nerves are also closely related. The nerve growth factor in nerve regeneration provides nutritional support and promotes axonal extension, which is generally believed to have positive clinical effects. However, thyroid hormon is thought to have a comprehensive and lasting effect on nerve regeneration. Recent studies suggest that the nerve growth factor and thyroid hormone have synergistic influence on the expression of certain proteins in the nerve regeneration process. Previously, some researchers tied the silicone tube to broken nerve ends when making models for rat sciatic nerve injuries. They injected drugs into silicone tube before tying it to broken nerve ends, or gave regular injection during the experiment. The silicone tube is a foreign thing to the rat’s body itself, which, on the one hand, had affected nerve regeneration and, on the other hand, needed to be taken out again. Besides, some made use of tissue engineering nerves to make the model for rat sciatic nerve injury. Although some obtained good results in tests, very few can really be applied to clinical medicine. Thus, this experiment selected the model of situ anastomosis for rat sciatic nerve transaction, which is of the most simple, reliable and practical value.This experiment aims to explore the influence of joint application of thyroid hormone (T3) and nerve growth factor (NGF) on peripheral nerve regeneration and functional recovery with sciatic nerve transection models.MethodsThe64healthy male adult SD rats, clean grade, being weighed240g-260g with average weight250±15g. Rats were intraperitoneal injected with2%sodium pentobarbital40mg/kg anesthesia after they had been weighted.The hind limbs were outreaching and limbs were fixed with rubber band at the operating table, cutting right hip rat hair. The conventional right hind limb disinfection was put on no bacteria towels with holes. Right thigh was about2cm longitudinal incision, and blunt dissection of the biceps femoris and vastus lateralis were free from right sciatic nerves, which was5mm away from the piriform margin. Sharp transection of the sciatic nerves, seek neurovascular landmarks on the bit ends together neatly with the help of surgical microscope, and then suture epineurium with a10-0non-trauma4-pin, knot moderately and unanimously, stop bleeding and suture rat skin incision. Then, the64SD rats were randomly divided into A, B, C and D, four groups with16in each group. A (T3+NGF) group:rats in this group received gastrocnemius muscle injection of T35μg/d and0.6μg/d NGF injection was put into the operated side gastrocnemius muscle; B (NGF) group:rats in this group received0.6μg/d NGF injection into the operated side gastrocnemius muscle and gastrocnemius muscle injection of normal saline5μg/d; C (T3) group:rats in this group received gastrocnemius muscle injection of T35μg/d and injection of normal saline0.6μg/d into the operated side gastrocnemius muscle; D (NS) group:rats in this group just received injection of5.6μg/d normal saline into the operated side gastrocnemius muscle respectively. The process lasted four weeks, and meanwhile they were observed within twelve weeks after operations. That included the general observation to all rats, determination of SFI, electroneurophysiology, the number of NF-H-positive axons, Western Blotting analysis of NF-H protein content, and the observation of electron microscopy.ResultsThe group of T3and NGF was compared with the other groups:(1) the general observation, the rat plantar ulcers appeared late and subsided earlier;(2) histological evaluation of nerve regeneration, the number of NF-H-positive axons was much more obvious; the levels of NF-H was higher; the axon of the electron microscope had a better recovery;(3) nerve function recovery, the sciatic functional index and neurophysiological measurement results were better than other groups. P<0.05, The difference was statistically significant.ConclusionT3and NGF promote sciatic nerve regeneration and functional recovery; T3and NGF have obvious synergistic effect on promoting the regeneration and function recovery of the peripheral nerve, properly,by improving the NF’s expression. |
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