Effects Of Regular Exercise On Cardiac Function Of Late Middle Drosophila With Nmnat Gene Differential Expression

ObjectiveTo study the effects of regular exercise at young age on cardiac systolic function, cardiac rhythm, climbing ability and lifespan at late middle age drosophila of cardiac Nmnat gene differential expression and explore heart anti-aging function of exercise of Nmnat.MethodsW1118, NMNAT-RNAi, NMNAT-HA, NMNAT-WR, NMNAT-H30 A lines were crossed to Hand-Gal4 flies respectively, then the female F1 progeny were collected and randomly divided into 10 groups, and incubated at 25℃ and 50% humidity with a 12-hour light/dark cycle.2 day-old flies underwent a 2.5 h, five times per week for 3 weeks exercise program starting at nine o’clock. Flies were exercised using the exercise device, which takes advantage of the flies’ instinctive negative geotaxis characteristic to iteratively execute climbing. Motion device was revolve around horizontal axis with counterclockwise rotation of 180°-stay 16s- clockwise 180°- stay 16 s, and so on.The Nmnat m RNA expression in cardiac muscle was measured by Real time q PCR at 7 days old. Heart function of drosophila was recorded by M-mode at 3 weeks of age and 5 weeks of age(after 2 week of rest). The flies exercise capacity was assessed using climbing index. 200 flies of each group are used to count survival rate, flies were transferred to fresh food every third day and mortality was recorded following each transfer. ResultsThe result of Nmnat m RNA expression in cardiac muscleThe expression of Nmnat in flies heart in Hand>nmnat RNAi-C group and Hand>nmnat-HA-C group were approximately decreased by 50 percent and increased by 42 percent respectively compared to Hand Gla4/+-C group(P<0.001, P<0.01). The expression of Nmnat in flies heart in Hand>nmnat-WR-C group and Hand>nmnat-H30A-C group were higher than Hand Gla4/+ group, among them there was significant difference in Hand>nmnat-H30A-C group(P<0.05).The result of heart function of fruit flies by M-mode(1) The result of heart function of fruit flies at 3 weeksof ageDD and SD were significantly increased(P<0.001), FS was obviously decreased(P<0.001) in Hand > nmnat RNAi group, compared with condition-matched Hand Gla4/+ group; By contrast with Hand>nmnat RNAi group, FS was significantly increased(P<0.001) with condition-matched Hand>nmnat HA group, Hand>nmnat WR group and Hand>nmnat H30 A group, SIAI was decreased(P<0.01) in Hand>nmnat WR group. Compared with Hand>nmnat RNAi-C group, FS in Hand > nmnat RNAi-E group increased significantly(P < 0.05); SIAI and AI were decreased(P<0.01, P>0.05) in Hand > nmnat H30A-E, compared with Hand > nmnat RNAi-E.(2) The result of heart function of fruit flies at 5 weeksof ageDD and SD were significantly increased(P<0.001), FS was obviously decreased(P<0.001) in Hand > nmnat RNAi group, compared with condition-matched Hand Gla4/+ group; Compared with Hand>nmnat RNAi-C group, FS in Hand>nmnat HA-C group, Hand>nmnat WR-C group and Hand>nmnat H30A-C group increased significantly(P < 0.05, P<0.001, P<0.001); By contrast with Hand > nmnat HA group, FS were obviously increased with condition-matched in Hand>nmnat H30 A group(P<0.05,P<0.01); SIAI was obviously decreased(P<0.001) in Hand>nmnat WR-C group and Hand>nmnat H30A-C group, compared with Hand>nmnat HA-C group. Compared with the control groups,FS was increased(P>0.05) in Hand Gla4/+-E group, Hand>nmnat RNAi-E group, Hand>nmnat WR-E group and Hand>nmnat H30A-E group, except Hand>nmnat HA group; Compared with the control groups,AI was decreased(P>0.05) in Hand>nmnat RNAi-E group, Hand>nmnat HA-E group, Hand>nmnat WR-E group and Hand>nmnat H30A-E group.The result of climbing index across agesThe exercise groups displayed decreased climbing index across ages. The control groups revealed decreased climbing index across ages from 3-week-old. CI in 1W-Hand Gla4/+-E group was higher than 1W-Hand Gla4/+-C group. Compared with Hand>nmnat RNAi-C group, CI was increased in Hand>nmnat RNAi-E group before 2-week-old. CI in Hand>nmnat HA-E group in the third week of exercise was significantly greater than age-matched Hand>nmnat HA-C group. After those compared with the control groups,CI was decreased in Hand Gla4/+E group, Hand>nmnat RNAi-E group, Hand>nmnat HA-E group.The result of mortality of drosophila Compared with Hand Gla4/+-C group, the survival curve of Hand>nmnat WR-C group and Hand>nmnat H30A-C group revealed right shift and up shift. Compared with Hand Gla4/+-C group, Hand>nmnat HA-C group, Hand>nmnat WR-C group, Hand>nmnat H30A-C group the survival curve of Hand>nmnat RNAi-C group displayed left shift and down shift, and the median survival time of the flies were shorten(P<0.001). The median survival time in Hand Gla4/+-E group was extended in Hand Gla4/+-C group(P<0.05). Compared with Hand>nmnat RNAi-C group, the survival curve of Hand>nmnat RNAi-E group revealed right shift and up shift, and the median survival time of the flies was extended(P<0.01). Compared with Hand>nmnat WR-C group, Hand>nmnat H30A-C group, the survival curve of the same genetic background has litter change in the exercised group.Conclusion(1) Nmnat is critical for maintaining cardiac systolic function and rhythm in the drosophila heart model.(2) Myocardial Nmnat knockdown declines to both cardiac systolic function and rhythm, which are substantially reduced when exercised early in life, and the exercise program can retard the decline of cardiac systolic function and arrhythmia of cardiac knockdown, overexpressioned and enzyme-inactive NMNAT aging flies.(3) The training in early life increases mobility of cardiac knockdown, overexpressioned and enzyme-inactive NMNAT aging flies, showed the higher motion adaptive of Nmnatoverexpressioned flies. And energy metabolism decreases with age, which causing the reduced of sports effect.(4) The training in early life extends the median survival time of flies with Nmnat gene differential expression, which may be related to increases the level of NAD+ to delay the aging process.