| Objective The influence of high temperature environment to human body is wide, including hot metabolism, energy metabolism, water salt metabolism, neuroendocrine system, cardiovascular system and so;The high temperature also can induce in vitro neuron to occur weakly perishes. Heat stress preconditioning can obviously improve the tolerant to heat. This experiment through: 1. Observed the influence of heat stress preconditioning to organize the NOS vigor, the nNOS protein expression as well as the behavior study influence to the mice brain, to reveal the mouse influence and the mechanism to the mice cerebrum of heat stress preconditioning. 2. Observes the influence of heat stress preconditioning to the acute heatstress mice brain to organize the NOS vigor, the nNOS protein and the gene expression as well as the behavior study influence, revealed the mechanism of how heat stress preconditioning protect the mice injure from heatstress.Methods 1. The adult healths Kunming male mice were ( weight 20±2.0g) stochastically divided into 3 groups: the control group, the period heat stress preconditioning group, the continue heat stress preconditioning group, each group has 30 mice. Duplicated the period and continue heat stress preconditioning mice model, after the pretreatment had ended 0, 6, 12, 24, 36h separately takes 6 animals to carry on the experiment. Uses the step-through test and the tiltboard test tested the mice's study memory function. 2. The adult healths Kunming male mice were ( weight 20±2.0g) stochastically divided into 4 groups: the control group, the heat stress group, the period heat stress preconditioning group, the continue heat stress preconditioning group, each group has 30 mice. Duplicated the period and continue heat stress preconditioning and heat stress mice model, after the pretreatment had ended 0, 6, 12, 24, 36h separately takes 6 animals to carry on the experiment. Uses the step-through test and the tiltboard test tested the mice's study memory function. And after heatstressed in 6h,12h,24h;used the NADPH-d histochemistry, the ABCimmunohistochemistry, the RT-PCR measure the activity of NOS and the levels ofprotein and gene expressions of nNOS and the gene expression in brain tissue.3. Bycortex neuron primary culture experimental technique, we observed the effect of heatstress which affected the growth, stock and synapse length in cultured cortexneurons.Resultsl.The results of praxiologyThe step-through test indicated that: 1. Compared with the control group, the The step-through test of the heat stress preconditioning group was decreased in Oh, 6h, while that of the periodical heat stress preconditioning group was increased than that of the control group in 24h(P<0.05)° 2. Compared with the control group heat stress group was decreased in 0h> 6h> 12h and the heat stress preconditioning group was decreased in Oh, 6h, while that of the heat stress preconditioning group was increased than that of the HS group in 12h(P<0.05)The titleboard test include: 1. Compared with the control group, the The step-through test of the heat stress preconditioning group was decreased in Oh, 6h, while that of the periodical heat stress preconditioning group was increased than that of the control group and CHP group in 24h(P<0.05). 2. Compared with the control group heat stress group was decreased in 01k 6h, 12h and the heat stress preconditioning group was decreased in Oh, 6h, while that of the periodical heat stress preconditioning group was increased than that of the HS group in 6h, 12h(P<0.05)2.The results of NADPH-d histochemistry and nNOS immunohistochemistry: Compared with the normal control group, the number of NADPH-d positive neurons and nNOS positive neurons in cerebral cortex and CAi of hippocampus of HS groupwere significantly increased in Sh^O.OS);and decreased in 12h.Compared with the control group, the number of NADPH-d positive neurons and nNOS positive neurons in cerebral cortex and CAi of hippocampus of heat stress preconditioning group were significantly increased in 6h(/><0.05), while were significantly decreased than those of the HS group in 6h> 24h(/><0.05). And there were no difference between the heat stress preconditioning groups. 3. The results of RT-PCRThe gene expression of nNOS. Compared with the normal control group, the electrophoresis strip of the nNOS products of the HS group were brighter than that of the control in 6h and the relative content of nNOS mRNA was significantly increased;while were lower in 12h(P<0.05);The value of optical density of electrophoresis strip of the heat stress preconditioning group, were lower than that of the HS group and the relative content of nNOS mRNA was significantly decreased in 6h and 24h(i><0.05);while those of the heat stress preconditioning group were significantly decreased than those of the HS group in 12h(P<0.05). 4.The results of cortex neuron primary cultureHeat stress can reduced the growth activity of cultured cortex neuron and synapse length become short(p<0.05). While heat stress preconditioning can protect the harmful effects from the heat stress induced the growth activity of cultured cortex neuron and synapse length was longer than that of HS group(/?<0.05). Conclusions Heat stress preconditioning can conspicuously protect the dysmnesy and the decrease of physical capacity caused by heat stress.And the mechanism is relate with the effect to the ability of NOS protein and the productiong of nNOS protein and gene.
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