Regulation Of Hypoxia On Pulmonary Endothelin-1 Expression In Plateau Animals And Modulation Of Nuclear Factor-κB

AimsNo doubt both environmental hypoxia and internal environmental hypoxia will influence organs' normal functions which are mostly related to changes of endothelin-l(ET-l) expression. ET-1 is involved in the hypoxic pulomanry vasoconstriction (HPV) which is part of pulmonary arterial hypertension (PAH) processing. Besides, ET-1 has effects on placenta growth This paper aims to study both the protein expressional and genetic adaptive principles in the lung tissue for Ochotona Curzoniae, Microtus Oeconomus, and Eospalax Baileyi, which are native of Qinghai-Tibetan plateau and admittedly have well acclimated to hypoxia. Besides, the effects on offspring after the pregnant animals have been exposed to stresses are also concerned. What's more, to learn the further mechanism the nuclear factor kB (NF-kB) as a mediator was focused on in the up-regulation of hypoxia on ET-1 expression. Research design and Methods1) To learn influences of internal environmental hypoxia, we injected Ochotona Curzoniae, Microtus Oeconomus, Eospalax Baileyi,and Mouse with CoCl₂ (i.p. 20, 40 and 60 mg/kg) and made a comparison among them.2) To learn influences of environmental hypoxia, we infused Ochotona Curzoniae, Microtus Oeconomus, and Mouse with a mixture of N₂-O₂ containing different oxygen pressure (10.8% and 8% O₂).3) Set up rat models of hypoxia stress (4h/d), restraint stress (4h/d) and the stresses in combination (4h/d) throughout the whole gestation and tested the lung ET-1 expression of male offspring..4) We designed two couples of ET-1 primers to test plateau animals' ET-1 mRNA.5) To learn the effect of NF-kB mediating the up-regulation on the lung ET-1 expression, we injected Ochotona Curzoniae, Microtus Oeconomus, and Mouse with the PDTC (an NF-kB antagonist).Contents of pulmonary ET-1 in all samples were tested by RIA. Acquisition of plateauanimals ET-1 cDNA is under RT-PCR.Results1) Injection of C0CI2 on Ochotona Curzoniae, Microtus Oeconomus, Eospalax Baileyi, and Mouse,Dose of 20mg/kg C0CI2 significantly increased lung ET-1 expression in Ochotona Curzoniae (P<0.01), Microtus Oeconomus (P<0.01), Eospalax Baileyi (P<0.05), and Mouse (P<0.001> Compared with 20mg/kg, dose of 40mg/kg CoCl2 significantly increased ET-1 expression in both Microtus Oeconomus, and Mouse (P<0.001 and P<0.05, respectively) but not Ochotona Curzoniae and Eospalax Baileyi. When compared with 40mg/kg , dose of 60mg/kg C0CI2 ET-1 expression in Ochotona Curzoniae was significantly increased (P<0.01), while in Microtus Oeconomus and Mouse was significantly decreased(P<0.05 and P<0.05, respectively) . Under dose of 40mg/km, Ochotona Curzoniae got a maximal ET-1 expression at 3h (P<0.001 vs control) which was larger than 6h (P<0.05) and returned to control level at 12h.2) Influences of acute hypoxia on Ochotona Curzoniae, Microtus Oeconomus, and Mouse lungs ET-1 expression5km hypoxia significantly induced the three species lung ET-1 expression and Ochotona Curzoniae, Microtus Oeconomus, had a larger increased range than Mouse. Under 7km hypoxia, Ochotona Curzoniae, and Microtus Oeconomus, respectively had no significant changes than under 5km hypoxia while Mouse with an increase (P<0.05) .3) The changes of offspring lung ET-1 expression after the pregnant animals have been exposed to stresses.Healthy adolescent male rats had a larger basal expression of lung ET-1 than adults (P<0.001). The three kinds of stresses induced a more sensitive response in adults than in adolescents. Hypoxia on mother rats increased adolescent offspring basal expression (P<0.05) and reduced both adolescent and adult offspring response to hypoxia stress. Restraint on mothers reduced only adult offspringbasal expression (P<0.05) with no response in adolescent to restraint but an enhanced response in adults (P<0.001). The mixture of both stresses reduced adults basal ET-1 (P<0.001). Besides, these adolescents represented an enhanced expression after exposure to the stresses in combination (P<0.001). 4) Microtus Oeconomus has a similarity score in ET-1 of 90%, 95%, 60% and 66% to rat, mouse, human and rabbit, respectively while Eospalax Baileyi has a similarity of 88%, 91%, 63% and 75% respectively. Besides, the similarity between Microtus Oeconomus and Eospalax Baileyi is 86%.Conclusions1) Comparing with Ochotona Curzoniae, Microtus Oeconomus, Eospalax Baileyi, and Mouse, we found that Ochotona Curzoniae and Eospalax Baileyi, have a better hypoxia tolerance under high dose of C0CI2 induced hypoxia and Ochotona Curzoniae apparently have a better hypoxia tolerance under lower oxygen pressure (7km).. However, Ochotona Curzoniae and Microtus Oeconomus seem to be more sensitive to lower dose of C0CI2 (40mg/kg) and higher oxygen pressure stress (5km) than Mouse.2) Healthy adolescent rats had a larger basal expression of lung ET-1 than adults. Adults are apparently more sensitive to the three kinds of stresses than adolescents. And exposure to different stresses on mothers will present different influences at different age of the offspring. The results seem to be complicated to explain.3) Data of ET-1 mRNA sequences showed that Microtus Oeconomus and mouse has the maxism similarity score among rat, mouse, human, rabbit, Microtus Oeconomus and Eospalax Baileyi which was followed by the similarity between mouse and rat. Molecular phylogenetic tree was in accord with the traditional taxonomy.4) Nuclear factor kB obviously mediates different oxygen pressure of hypoxia induced lung ET-1 expression in Microtus Oeconomus and Mouse. It also mediates 5km hypoxia-induced Ochotona Curzoniae lung ET-1 expression;however, its effect under 7km hypoxia seems less apparently.. We guess other transcription factors are involved.