Effects Of Exhausted Exercise On The Expression Of Nitric Oxide Synthase In Paraventricular Nucleus And Supraoptic Nucleus In Rats

Nitric Oxide (NO) as a kind of neurotransmitter plays an important role in the information communication of the neuron. Nitric Oxide Syntheses (NOS), as a key factor of NO synthesization, plays a very important role in performing its biological function. Since the research of NO was introduced into sports medicine, researchers have launched different researches from blood, viscera and brain tissue etc, already, found that NO relates to the exercise-induced fatigue. A few research to getting deeply the nucleus group in the research between NO and exercise-induced fatigue. We can see all of NOS positive neuron in hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON), but no reports about the relations between them.This experiment researched the relations between Neuronal Nitric Oxide Synthase( nNOS ) positive neurons in PVN and SON to exercise-induced fatigue by using exhausted exercise models of rats.Methods: 20 male rats were randomly divided into control group, instant group, 0.5h group and 4h group after the exhausted exercise, each group has 5 rats. Once exhausted exercise models were set up by using common exhausted exercise method (Tanaka M). With ABC immunohistochemistry technique, it was studied that the number and gray degree of the nNOS positive neurons in PVN and SON, and carry on semiquantitative analysis.Results: After exhausted exercise, compare with control group, a significantly decrease nNOS positive neuron quantity with dye depth of instant group and 0.5h group in PVN (P <0.001). 4h group have no remarkable difference (P> 0.05). Compared among each group 0.5h significantly decreased than instant and 4h group (P <0.001), while 4h group is increased than instant group (P <0.05), it is near to the control group. After exhausted exercise, compare with control group, a significantly decrease nNOS positive neuron quantity with dye depth of instant group and 4h group in SON (P <0.05). 0.5h group decreased significantly (P <0.001). Comparedamong each group 0.5h significantly decreased than instant and 4h group (P <0.001), while 4h group have no remarkable difference to compare to instant group (P> 0.05).Results shows: Expression of nNOS positive neuron in PVN and SON obviously decreased compared with control group after exhausted exercise. At half an hour after exhausted exercise the changes are the most significantly. At 4h after exercise expression in PVN is already close to control group; While the expression of nNOS positive neurons in SON have a remarkable difference from the control group. The expression of nNOS positive neuron in PVN is basically consistent with SON at the initial stages after exhausted exercise .The exercise-induced fatigue is the most sharp at half an hour after exhausted exercise. The expression of nNOS positive neurons has a significant difference between PVN and SON at the 4h after exhausted exercise. The expression of nNOS positive neurons in PVN is basically close to control group at 4h after exhausted exercise, that means the exercise-induced fatigue had already basically recovered. But the expression of nNOS positive neurons in SON is lower than that of control group, that means exercise-induced fatigue can't recover yet.Conclusion: Exhausted exercise can reduce expression of nNOS the positive neuron in hypothalamaic PVN and SON in rats. This suggests that the reduction of nNOS positive expression in PVN and SON is involved in forming the central exercise-induced fatigue of exhausted exercise.