Experimental Study Of Progesterone On The Regeneration Of Injured Facial Nerve In Female Rats

Objective: To investigate the role of progesterone on the regeneration of injured facial nerve in adult ovariectomized female rats.Methods: 32 female Wistar rats were first performed ovariectomy. Two weeks later, the right facial nerves crush models were established. Then,All rats were randomized into two groups.Rats in group A(PROG treatment group) had hip intramuscular administration of progesterone Injection (0.2 mL/d) while those in group B(DMSO control group) had hip intramuscular administration of Dimethyl Sulfoxide (0.2 mL/d). In addition,another 4 female Wistar rats were taken as normal control group. Without receiving any treatment,facial nerve and inferior-middle part of pons ( containing facial nucleus)Were directly harvested to perform Immunohistochemistry staining. 1)The distal ends of the right injured facial nerve were harvested at days 7,14, 21,28 after surgery. Hematoxylin and Eosin staining and ponceau G - Brilliant green SF staining of the samples were done for measurement of the numbers of myelinated nerve fibers in unit field of vision and the thickness of the myelin. Ultrastructure of nerve fiber were observed under transmission electron microscope at 14 days after surgery. 2) The distal ends of the right injured facial nerve were harvested at days 7,14, 21,28 after surgery. Immunohistochemistry staining of the samples were done for observing the expression of GDNF. 2) The inferior-middle part of pons( containing facial nucleus) were harvested at days 7,14, 21,28 after surgery. Immunohistochemistry staining of the samples were done for observing the expression of GDNF.Result: 1)The numbers of myelinated nerve fibers and the thickness of the myelin in PROG treatment group at diferent intervals were significantly higher than those in DMSO control group, t-test showed significant difference between the two groups(P<0.01). 2)The expressions of GDNF in facial nerves : the model groups were significantly higher than the normal control group at different time points, t-test showed significant difference between the two groups(P<0.01).The PROG treatment group were significantly higher than the DMSO control group at 7, 21,28 days after surgery(P<0.01).But, there were no significant difference between the two groups at 14 days after surgery(P>0.05). 3)The expressions of GDNF in facial nucleus: the model groups were significantly higher than the normal control group at different time points, t-test showed significant difference between the two groups(P<0.01). The PROG treatment group were significantly higher than the DMSO control group at different time points, t-test showed significant difference between the two groups(P<0.01). Conclusion: The progesterone could facilitate facial nerve regeneration in that it promotes the expression or transportation of neurotrophic factors GDNF.