| Objective:Established model of CIH rats to explore the effect of chronic intermittent hypoxia on genioglossus of rats, and the effect of nerve growth factor on genioglossus of rats with CIH. We hope to find out a new way for treatment of OSAHS.Method:Established model of CIH rats by homemade intermittent hypoxia cabin.28SD rats were randomly divided into four groups:normal control group, CIH group, CIH+NGF group, CIH+anti-NGF group,7rats in every group. Normal control group were placed in the cabin with air circulation, and the other groups rats were in intermittent hypoxia cabin, They were treated8hrs/d for5weeks.CIH group and the control group rats were given daily intravenous injection of saline,1ml/Kg, CIH+NGF group and CIH+anti-NGF group were given daily lug/Kg NGF,2ug/Kg anti-NGF with tail vein injection, respectively. At the end of5weeks, all the rats were anesthetized with chloral hydrate by0.3ml/100g, then isolated rat hypoglossal nerve and genioglossus. End of genioglossus were connected to tension transducer, recorded genioglossus twitch tension with a single stimulus to neural stem and then given a continuous stimulation of muscle induce genioglossus fatigue and recorded genioglossus tonic contraction curve. Part of them was stored with10%formalin solution, embedded in paraffin for HE staining and immunohistochemistry showing that NGF expression; and another part was placed at freezer with-70℃, MDA levels of genioglossus of rat were measured by TBA, SOD levels were measured with Hydroxylamine, acetylcholinesterase activity of rat genioglossus were measured by TNB.Result:The body weight of rats in each group had no significant difference (P>0.05) before and after the experiment. There were no significant variances of twitch tension of genioglossus among groups (P>0.05). CIH group,CIH+NGF group, and CIH+anti-NGF group, were significantly decreased in twitch tension50%-decay time compared with the control group (P<0.01), compared with CIH+NGF group, twitch tension50%-decay time in CIH group and CIH+anti-NGF group significantly decreased (P<0.05). There were no significant difference in twitch tension50%-decay time between CIH group and CIH+anti-NGF group (P>0.05). SOD levels and AChE activity in CIH group, CIH+NGF group, CIH+anti-NGF group genioglossus were significantly lower (P<0.05), while MDA levels were significantly higher than the control group (P<0.05), AChE activity and SOD levels of CIH+NGF group were significantly higher than the CIH group, and MDA levels were significantly lower (P<0.05). Genioglossus tissue cross section showed muscle fiber cross-sectional area of CIH group, CIH+NGF group, CIH+anti-NGF group were less than the normal control group (P<0.05), but among CIH group, CIH+NGF group and CIH+anti-NGF group, these differences were no statistically significant (P>0.05). Expression of NGF were seen in Normal control rats genioglossus tissue, but the expression of NGF in CIH group, CIH+NGF group and CIH+anti-NGF group was significantly lower than the normal control group (P<0.05). NGF expression of genioglossus in CIH+NGF group was significantly higher than in the CIH group and CIH+anti-NGF group (P<0.05).Conclusion:1.CIH can cause the damage of genioglossus structure and neuronal activity and increase the muscle fatigue.2. NGF can partially improve genioglossus fatigue in CIH rats, and the mechanism may be reducing oxidative stress and repairing the damage of genioglossus structure and neuronal activity. |
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