The Protective Effects Of Taurine-zinc Coordination Compound On Brain And Physical Ability Of Cold Stress Rat And The Relative Mechanisms

Objective When the animal acute (short-term) exposed in cold environment, it cancause cold stress rapidly. The central nervous system is very sensitive to cold stressand it can cause dysfunction in learning and memory, behavior and emotion. Tau playsa key role in brain development and maintenance of brain function, which mightprotect neurons from impairments of cold stress. On the other hand, Zn is generallyacknowledged as a protective agent of brain function. It is definite that the zinc canresist effects of fatigue. We observed learning and memory, NOS activity, the proteinsof nNOS and HIF-1a expression in cortex and hippocampus, to study the protectiveeffects of taurine-zinc coordination compound on brain and physical ability of coldstress rat and the relative mechanisms.Methods 80 male Wistar rats were randomly derided into 4 groups, including controlgroup, ordinary temperature water group, TZC group, and pure cold stress group, eachgroup composed of 20 rats. 30 days later, cold stress rat model was duplicated. Afterthe balneum frigidum had ended 2h, 10 rats of each group were randomly chosen tocarry out the experiment of Y-labyrinth. Other rats were tested by NADPH-dhistochemistry, ABC immunohistochemistry and RT-PCR to measure the activity ofNOS and the levels of protein and gene expressions of nNOS and HIF-1a in braintissue.Results1. The results of weight change and behavior test(1) The weight change indicates that: At the time of 2h and 4h after cold stress, theweight increase of TZC group, pure cold group were significant lower than controlgroup, ordinary temperature water group(P＜0.05); At the time of 6h, there was onlypure cold group significant lower than control group and ordinary temperature watergroup(P＜0.05). While 8h after cold stress, there was no significant difference amongall groups(P＞0.05). (2) The Y-labyrinth test indicated that: Compared with the control group, the rightnessrate of the pure cold group significantly decreased(P＜0.05), and it was also lower thanthe ordinary temperature water group and TZC group(P＜0.05); While there was nosignificant difference among the control group, ordinary temperature water group andTZC group(P＞0.05).(3) The slope test indicated that: At 2h and 4h after balneum frigldum, the slope angle ofpure cold group was lower than control group(P＜0.05), and compared with theordinary temperature water group and TZC group, it also significantlydecreased(P＜0.05); At 2h after balneum frigidum, the slope angle of TZC group waslower than the control group(P＜0.05). On the other time, there was no significantdifference among the experiment groups.2. The results of NADPH-d histochemistry and nNOS immunohistochemistry:There was no difference on cell conformation and distribution patterns of NADPH-dand nNOS positive neurons in cortex and hippocampus among control group andexperimental groups. The number of NADPH-d and nNOS positive neurons incerebral cortex and CA₁ of hippocampus of pure cold group was higher than controlgroup(P＜0.05). Compared with the ordinary temperature water group and TZC group,it also significantly increased(P＜0.05); While there were no significantly differencesamong normal control group, ordinary temperature water group and TZCgroup(P＞0.05). In CA₃ and DG of hippocampus, there were no significant differencesamong all the groups(P＞0.05).3. The results of RT-PCR(1) The gene expression of nNOS. Compared with the normal control group, theelectrophoresis strip of the nNOS products of the cold stress group were brighter thanthat of the control group and the relative content of nNOS mRNA significantlyincreased(P＜0.05), it was also higher than the ordinary temperature water group andTZC group. While there were no significantly differences among normal control group, ordinary temperature water group and TZC group(P＞0.05).(2) The gene expression of HIF-1a. HIF-1a mRNA was not observed in control groupand ordinary temperature water group. Compared with control group, there weresignificant increases of HIF-1a mRNA in TZC group and pure cold group(P＜0.05);Meanwhile, the expression of HIF-1a mRNA in TZC group was significantlyincreased, compared with the pure cold group(P＜0.05).Conclusions Cold stress can cause impairments on cortical and hippocampal neuronsas well as ability of learning and memory. TZC could aggravate the learning andmemory disorders caused by cold stress. It suggests that the most importantmechanisms are related to decrease of the NOS activity, protein and gene expressionsof nNOS, as well as increase of gene expression of HIF-1a mRNA.