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學(xué)術(shù)報告廳

 

學(xué) 術(shù) 報 告 廳

譯者:鄭薇薇(哈爾濱醫科大學(xué)公共衛生學(xué)院,哈爾濱 150001)
早期膳食長(cháng)期程序性效應的實(shí)驗數據
Experimental evidence for longterm programming effects of early diet
  摘 要:在胚胎或胎盤(pán)發(fā)育的特殊時(shí)期進(jìn)行營(yíng)養控制,盡管不會(huì )對胚胎的重量產(chǎn)生影響,但可以導致胚胎器官發(fā)育過(guò)程中的實(shí)質(zhì)性改變。尤其是使營(yíng)養素受限制幼仔的腎臟和脂肪量發(fā)生了較大的定向改變,同時(shí)瘦素,胰島素樣生長(cháng)因I/II和糖皮質(zhì)激素受體的mRNA水平增高。對幼仔時(shí)期的營(yíng)養素限制,會(huì )使剛成年大鼠出現心血管的壓力反射變遲鈍。交感神經(jīng)刺激血清瘦素水平增加,這在對照組是不會(huì )出現的,這說(shuō)明了脂肪細胞應激對敏感性的恢復。總之,對早期發(fā)育時(shí)期的營(yíng)養素整體限制,一定形式上改變了成年鼠的生理狀況,說(shuō)明了如果再給予相應的環(huán)境刺激則會(huì )對后期疾病產(chǎn)生誘導作用。
  關(guān)鍵詞:胚胎發(fā)育;mRNA;瘦素;胚胎;應激;腎臟;脂肪
1 成人疾病的程序化發(fā)展
  高血壓和肥胖是冠心病的主要威脅因素,是超過(guò)50歲的人群的一種常見(jiàn)致死原因1。由全世界不同群體得到的廣域的流行病學(xué)證據顯示胎兒接觸到的營(yíng)養及激素環(huán)境的定向改變對后期的心血管疾病具有決定性的影響2,3。流行病學(xué)及動(dòng)物實(shí)驗也都說(shuō)明了適時(shí)的母體營(yíng)養是后期結果的關(guān)鍵決定因素4-6。確切的說(shuō),這種影響也可發(fā)生在出生時(shí)體重無(wú)差異的情況下。事實(shí)上,雖然能量攝入相差的范圍較大,但是體重的差異卻并不很大,這一點(diǎn)很令人吃驚7。子宮內的母體營(yíng)養素限制的長(cháng)期后果呈現出相關(guān)性,或者這種相關(guān)性會(huì )通過(guò)營(yíng)養素恢復的時(shí)間、強度、持續時(shí)間而被放大8, 9。而后,營(yíng)養素的攝入變得越來(lái)越重要,特別是在出生后,此時(shí)營(yíng)養素攝取以及身體生長(cháng)發(fā)育已不再受限制,個(gè)體可以實(shí)現全部生長(cháng)潛勢。在本綜述中,我們重點(diǎn)收集腎臟和脂肪發(fā)育的宮內程序性影響,其前提是腎臟免疫功能低下,脂肪儲存過(guò)多與成人高血壓具有強相關(guān)性10。
2 胎兒程序影響的動(dòng)物模型
  小型及大型動(dòng)物模型的研究都發(fā)現,無(wú)論是在妊娠期還是在確定懷孕的一段時(shí)期實(shí)施母體膳食控制,都會(huì )對健康產(chǎn)生長(cháng)期后果6, 11。但是不同動(dòng)物模型產(chǎn)生的反映差異很大,這反映了不同種屬動(dòng)物存在生長(cháng)發(fā)育時(shí)強加給母親的代謝改變有很大差異。大鼠在妊娠期對營(yíng)養失調呈現出獨特的易損性,這可能是由于它們窩生的特點(diǎn)、妊娠期短和妊娠后期幾天胎盤(pán)及胎兒的迅速生長(cháng)的原因。大鼠的妊娠產(chǎn)物在胚胎發(fā)育過(guò)程中顯示了罕見(jiàn)的蛋白質(zhì)添加比率(估計是羊和人類(lèi)胎兒的23倍12)相對于母體體重在足月時(shí)總體重量相對較高(胎兒的總體體重是母體體重的25%-35%羊是7%-10%,人是3%-5%)。另外,羊的胎兒在胎盤(pán)生長(cháng)中的快相過(guò)程與人類(lèi)胎兒相似13。通過(guò)羊的繁殖發(fā)現:它們如同人和一些單幼仔動(dòng)物,經(jīng)過(guò)一個(gè)長(cháng)期的妊娠過(guò)程在出生時(shí)有相似的體重和一個(gè)發(fā)育成熟的下丘腦-腦垂體軸。
3 營(yíng)養干預和胎兒的程序影響宏
  量或者微量營(yíng)養素整體缺乏或者失調是否直接對胚胎發(fā)育造成負面影響,仍是一個(gè)存有爭議的問(wèn)題。迄今為止,從已有的流行病學(xué)和動(dòng)物實(shí)驗得到的比較公認的看法是宏量營(yíng)養素對程序性影響的作用較大[4, 14]。一個(gè)最有特性的胎兒程序設計的動(dòng)物模型是大鼠,它對高低蛋白質(zhì)膳食的特性都已經(jīng)進(jìn)行了檢測11, 15。這些試驗重復顯示了,在妊娠全過(guò)程11或者特殊時(shí)期,母體消耗低蛋白膳食將導致后代的血壓升高16。影響的大小部分是由于暴露的時(shí)間決定的,并且部分研究還顯示了起影響有性別差異。值得注意的是,低蛋白飲食對脂肪沉積無(wú)任何促進(jìn)作用,這與高蛋白的飲食恰好相反15。然而,在子宮內暴露于高或低蛋白的任何程序性效應在晚期的脂肪沉積方面都顯示對出生后膳食的依賴(lài)型。大鼠的幼仔在胎兒發(fā)育時(shí)期的高蛋白膳食,只有其在出生后喂食標準飼料時(shí)才會(huì )變得肥胖15。同時(shí),報告說(shuō)對于小鼠,出生后過(guò)度的營(yíng)養消耗伴隨低蛋白膳食幾乎會(huì )使1318出現肥胖癥和壽命縮短的現象。這種反映的程度不是很清楚,可能是由于脂肪細胞內部的特殊改變造成的,或者與食欲調節的中心介導效應有關(guān)。
4 妊娠營(yíng)養干預的組織特異性
  對妊娠大鼠在整體上的營(yíng)養素限制將導致全部后代出現子宮內發(fā)育遲緩,但只會(huì )使其在青春期后才出現肥胖。這種模型的后代顯示了成年合并癥,這些合并癥包括坐式/靜態(tài)行為(sedentary behaviour)19、高胰島素血癥和高瘦素水平20, 21。肥胖與食欲過(guò)盛相關(guān)聯(lián),無(wú)論是標準膳食還是高碳水化合物膳食均可觀(guān)察到。這些大鼠也會(huì )出現高血壓,這種效應可以通過(guò)生長(cháng)激素治療糾正22。迄今為止,這個(gè)模型沒(méi)有腎臟的負面影響的報道。
  與人類(lèi)流行病學(xué)和大型動(dòng)物試驗相比該大鼠動(dòng)物模型高血壓的程序影響具有更高的放大性。收縮壓增高20-40mmHg既發(fā)生在孕期的低蛋白飲食11的情況,也發(fā)生在孕期鐵攝入不足23及脂肪過(guò)量攝入24的情況。受損腎臟發(fā)育伴隨低蛋白飲食或者鐵缺乏可能導致較高的血壓23, 25。對母體高脂肪飲食的腎功能的后期結果沒(méi)有報道,盡管雄性及雌性個(gè)體血清腎上腺皮質(zhì)素都會(huì )增加,但是只有雌性后代的血壓增高24。這個(gè)模型有趣的是,血管的內皮功能異常,例如內皮組織依賴(lài)性擴張(endothelium dependent dilation)不具有性別差異,同時(shí)這個(gè)模型也不能說(shuō)明這種機制與高血壓的進(jìn)展有關(guān)。
  長(cháng)期的食用低蛋白飲食的不良后果不僅僅局限血壓的改變,還包括異常的胰腺發(fā)育情況,例如,β-細胞的量、小島血管化作用都降低26。這種缺陷可以通過(guò)牛磺酸補充克服,牛磺酸具有恢復胎兒小島血管內正常體積和細胞密度的有益效應27。牛磺酸也可預防血管內皮生長(cháng)因子和胎兒肝激酶-1受體的低表達。還不知道牛磺酸是否也同樣可以調整有害的心血管后果。此外,另一方面,盡管胰腺功能受損,其后代出生存在牛磺酸不足損害也不會(huì )引起肥胖癥。
5 胎兒時(shí)期程序性影響成年后
疾病的機制

  腎臟—一個(gè)涉及胎兒程序性影響的基礎器官。大型動(dòng)物,例如羊,早期的腎臟發(fā)育對于過(guò)度的腎上腺皮質(zhì)類(lèi)固醇高度敏感28。一個(gè)胎兒腎臟成熟的關(guān)鍵時(shí)期是原腎的發(fā)育時(shí)期及隨后的退化時(shí)期29,與著(zhù)床時(shí)期一致。在這個(gè)時(shí)期暴露高水平的糖皮質(zhì)激素對糖皮質(zhì)激素受體的數量沒(méi)有影響,但是,可出現很多腎功能的直接后果,尿囊液中重量克分子滲透壓濃度、鈉及氯化物含量降低和鉀濃度增高30。這些特殊的適應已經(jīng)被解釋為早產(chǎn)兒中腎內Na 、K、ATPase活性的增量調節。母體低蛋白膳食生育的幼仔的增量調節也相似的提高31。妊娠早期受到地塞米松作用的胎兒,同時(shí)會(huì )在妊娠晚期注射3d的血管緊張素II的侵潤32,顯示出了尿流量率的增加,這證實(shí)了存在腎功能的改變。后代持續出現較高靜息血壓而不是不受應激的血壓28。
  大鼠后代,在子宮內暴露于低蛋白飲食產(chǎn)生的較高的血壓很可能是由于腎單位數量的減少33,也可能是由于在子宮內暴露于過(guò)高的糖皮質(zhì)激素34,抑制了腎素血管緊張素系統35。下面的研究支持這種觀(guān)點(diǎn),羊早期到中期妊娠過(guò)程限制能量,其后代腎臟糖皮質(zhì)激素受體和糖皮質(zhì)激素反映應答基因,如血管緊張素原2-受體ImRNA增加36。后代腎單位數量以及11β羥化類(lèi)固醇脫氫酶2型的活性減少37, 38,因此導致了繼發(fā)應激敏感性的增加。有趣的是,作為機體的一個(gè)功能器官,腎臟在營(yíng)養素限制組和對照組后代的重量隨年齡增長(cháng)而減少。同時(shí),營(yíng)養限制組后代的血壓由低于對照組轉變成高于對照組。這種血壓升高的轉變是伴隨著(zhù)子宮內營(yíng)養素限制的,因此顯示出了一種年齡相關(guān)過(guò)程。心血管壓力反射的復位是維持血壓的一個(gè)重要因素,這種壓力反射是血壓移動(dòng)改變中維護中央壓力的要點(diǎn):如果不能完全復位則后期高血壓出現的危險性就會(huì )增加39。母體營(yíng)養素限制的綿羊的后代顯示出了在注射血管緊張素II后對壓力反射敏感性的遲緩,因此,相對于對照組,心動(dòng)過(guò)速伴隨中央血壓的降低是可能的39, 40。在生命早期的關(guān)鍵時(shí)期,局部血管緊張素II活性增強如孤束核和竇房節是可能的機制之一。
  胎兒脂肪的增長(cháng)是受營(yíng)養的嚴格調控的,并對母親妊娠期間營(yíng)養狀況的變換高度敏感。妊娠早期開(kāi)始的營(yíng)養素限制可增強胎兒脂肪沉積,但母體在妊娠后期營(yíng)養不足卻減少胎兒脂肪沉積41。限制母體營(yíng)養素的后代出現脂肪含量增高,并且保持這種高的狀態(tài)。足月時(shí),脂肪過(guò)多伴隨有瘦素、增加的胰島素-生長(cháng)因子I/II和糖皮質(zhì)激素受體的mRNA的量增高36, 37。這些特殊效應在營(yíng)養素限制時(shí)期伴有母體血漿皮質(zhì)醇(maternal plasma cortisol)、甲狀腺激素、瘦素濃度的降低36, 42。而后,剛成年的個(gè)體,營(yíng)養素限制的幼仔顯示出交感神經(jīng)刺激后血漿瘦素增加,這種刺激在對照組沒(méi)有被觀(guān)察到,說(shuō)明了脂肪細胞對應激的敏感性恢復40。在生命晚期的特殊時(shí)期增加營(yíng)養是否會(huì )使這種癥狀?lèi)夯写M(jìn)一步證實(shí),舉個(gè)例子,在哺乳期,脂肪是身體最快的增長(cháng)部位。
  總之,胚胎及胎盤(pán)發(fā)育時(shí)期的營(yíng)養素限制程序化影響成人的生理機能39。這提示成年后再經(jīng)歷某些環(huán)境刺激時(shí)發(fā)生某些疾病的易感性。
參考文獻:
  1. Law CM, Shiell AW. Is blood pressure inversely related to birth weight﹖ The strength of evidence from a systematic review of the literature. J Hypertens, 1996, 148 935-941.
  2. Barker DJ. In utero programming of chronic disease. Clin SciLond, 1998, 952 115-128.
  3. Curhan GC, Willett WC, Rimm EB, et al. Birth weight and adult hypertension, diabetes mellitus, and obesity in US men. Circulation, 1996,15 9412 3246-3250.
  4. Roseboom TJ, van der Meulen JHP, Osmond C, Barker DJP, Ravelli ACJ and Blecker OP. Plasma lipid profile in adults after perinatal exposure to famine. Am J Clin Nutr, 2000, 72  1101-1106.
  5. Roseboom TJ, van der Meulen JHP, Osmond C, Barker DJP, Ravelli ACJ. S.-T. von Montfrans GA, Michels RPJ and Blecker OP. Coronary heart disease in adults after perinatal exposure to famine. Heart, 2000, 84  595-598.
  6. Symonds ME, Pearce S, Bispham J, Gardner DS and Stephenson T. Timing of nutrient restriction and programming of fetal adipose tissue development. Proc Nutr Soc, 2004, 63  (In press).
  7. Symonds ME, Gardner DS, Pearce S and Stephenson T. in Fetal Nutrition and Adult Disease-Programming of chronic disease through fetal exposure to undernutrition ed. S. C. Langley-Evans 353-380 CAB International, Oxford, 2004.
  8. Dandrea J, Wilson V, Gopalakrishnan G, Heasman L,  Budge H, Stephenson T and Symonds ME. Maternal nutritional manipulation of placental growth and glucose transporter-1 abundance in sheep. Reprod, 2001, 122  793-800.
  9. Symonds ME, Budge H, Stephenson T and McMillen IC. Fetal endocrinology and development-manipulation and adaptation to long term nutritional and environmental challenges. Reprod, 2001, 121 853-862.
  10. Hall JE. The kidney, hypertension, and obesity. Hypertension, 2003, 413 Pt 2 625-633.
      11. Langley-Evans SC. Fetal programming of cardiovascular function through exposure to maternal undernutrition. Proc Nutr Soc, 2001, 60  505-513.
  13. Heasman L, Clarke L, Dandrea J, Stephenson T and Symonds ME. Correlation of fetal number with placental mass in sheep. Cont Rev Obs Gynecol,1998, 10  275-280 .
  14. Godfrey K, Robinson S, Barker DJP, Osmond C and Cox V. Maternal nutrition in early and late pregnancy in relation to placental and fetal growth. BMJ, 1996, 312  410-414.
  15. Daenzer M, Ortmann S, Klaus S, et al. Prenatal high protein exposure decreases energy expenditure and increases adiposity in young rats. J Nutr, 2002, 1322 142-144.
  16. Kwong WY, Wild AE, Roberts P, Willis AC, and Fleming TP. Maternal undernutrition during the preimplantation period of rat development causes blastocyst abnormalities and programming of postnatal hypertension. Development, 2000, 127  4195-4202.
  17. Ozanne SE, Nave BT, Wang CL, Shepherd PR, Prins J, and Smith GD. Poor fetal growth causes long-term changes in expression of insulin signalling components in adipocytes. Am J Physiol, 1997, 273  E46-E51.
  18. Ozanne SE, Hales CN. Lifespan Catch-up growth and obesity in male mice. Nature, 2004, 4276973 411-412.
  19. Vickers MH, Breier BH, McCarthy D, et al. Sedentary behavior during postnatal life is determined by the prenatal environment and exacerbated by postnatal hypercaloric nutrition.Am J Physiol Regul Integr Comp Physiol, 2003, 2851 R271-3.
  20. Vickers MH, Breier BH, Cutfield WS, et al. Fetal origins of hyperphagia, obesity, and hypertension and postnatal amplification by hypercaloric nutrition. Am J Physiol Endocrinol Metab, 2000, 2791 E83-7.
  21. Vickers MH, Reddy SIBA, and Breier BH. Dysregulation of the adipoinsular axis-a mechanism for the pathogenesis of hyperleptinemia and adipogenic diabetes induced by fetal programming. J. Endocrinol, 2001, 170  323-332.
  22. Vickers MH, Ikenasio BA, Breier BH, et al.  Adult growth hormone treatment reduces hypertension and obesity induced by an adverse prenatal environment. J Endocrinol, 2002, 1753 615-23.
  23. Gambling L, Dunford S, Wallace DI, et al. Iron deficiency during pregnancy affects postnatal blood pressure in the rat. J Physiol, 2003, 552Pt 2 603-610.
  24. Khan IY, Taylor PD, Dekou V, et al. Gender-linked hypertension in offspring of lardfed pregnant rats. Hypertension, 2003, 411 168-75.
  25. Nwagwu MO, Cook A, and Langley-Evans SC. Evidence of progressive deterioration of renal function in rats exposed to a maternal low-protein diet in utero. Brit J Nutr, 2000, 83  79-85.
  26. Snoeck A, Remacle C, Reusens B, et al. Effect of low protein diet during pregnancy on the fetal rat endocrine pancreas. Biol Neonate, 1990, 572 107-118.
  27. Boujendar S, Arany E, Hill D, et al. Taurine supplementation of a low protein diet fed to rat dams normalizes the vascularization of the fetal endocrine pancreas. J Nutr, 2003, 1339 2820-2825.
  28. Dodic M, Hantzis V, Duncan J, Rees S, Koukoulas I, Johnson K, Wintour EM, and Moritz K. Programming effects of short prenatal exposure to cortisol. FASEB J, 2002, 16  1017-1026.
  29. Wintour EM, Alcorn D, Butkus A, Congiu M, Earnest L, Pompolo S, and Potocnik SJ. Ontogeny of hormonal and excretory function of the meso-and metanephros in the ovine fetus. Kidney Int, 1996, 50  1624-1633.
  30. Peers A, Hantzis V, Dodic M, Koukoulas I, Gibson A, Baird R, Salemi R, and Wintour EM. Functional glucocorticoid recetpors in the mesonephros of the ovine fetus. Kidney Int, 2001, 59  425-433.
  31. Bertram CE, Trowern AR, Copin N, Jackson AA, and Whorwood CB. The maternal diet during pregnancy programs altered expression of the glucocorticoid receptor and type 2 11-hydroxysteroid dehydrogenase Potential molecular mechanisms underlying the programming of hypertension in utero. Endocrinology, 2001, 142  2841-2853 .
  32. Moritz K, Johnson K, Douglas-Denton, Wintour REM, and Dodic M. Maternal glucocorticoid treatment programs alterations in the renin-angiotensin system ovine fetal kidney. Endocrinology,2002, 143  4455-4463 .
  33. McMullen S, Gardner DS, Langley-Evans SC. Prenatal programming of angiotensin II type 2 receptor expression in the rat. Br J Nutr, 2004, 911 133-140.
  34. Langley-Evans SC, Phillips GJ, Benediktsson R, Gardner DS, Edwards CRW, Jackson AA, and Seckl JR. Protein intake in pregnancy, placental glucocorticoid metabolism and the programming of hypertension. Placenta, 1996, 17  169-172.
  35. Woods LL, Ingelfinger JR, Nyengaard JR, and Rasch R. Maternal protein restriction suppresses the newborn reninangiotensin system and programs adult hypertension in rats, 2001, 49  460-467.
  36. Bispham J, Gopalakrishnan GS, Dandrea J, Wilson V, Budge H, Keisler DH, Broughton Pipkin F,  Stephenson T, and Symonds ME. Maternal endocrine adaptation throughout pregnancy to nutritional manipulation consequences for maternal plasma leptin and cortisol and the programming of fetal adipose tissue development. Endocrinology, 2003, 144  3575-3585.
  37. CB Whorwood, KM Firth, H Budge and ME Symonds, Maternal undernutrition during earlyto  midgestation programmes tissuespecific alterations  in the expression of the glucocorticoid receptor, 11-hydroxysteroid dehydrogenase isoforms and type 1 angiotensin Ⅱ receptor in neonatal sheep. Endocrinology, 2001, 142  1778-1785.
  38. Passingham L, Kurlak LO, Gopalakrishnan G, Budge H, Rhind SM, Rae MT, Kyle CE, Stephenson T, and Symonds ME. The effect of maternal nutrient restriction during early to mid-gestation on the enzyme activity of 11 beta hydroxysteroid dehydrogenase type 2 in sheep kidneys of 3 year old offspring. Early Hum Dev, 2004, (In press).
  39. Gardner DS, Pearce S, Dandrea J, et al. Peri-implantation undernutrition programs blunted angiotensin II evoked baroreflex responses in young adult sheep. Hypertension, 2004, 436  1290-6.
  40. Gopalakrishnan GS, Gardner DS, Rhind SM, et al. Programming of adult cardiovascular function after early maternal undernutrition in sheep. Am J Physiol Regul Integr Comp Physiol, 2004, 2871 R12-20.
  41. Budge H, Edwards LJ, McMillen IC, et al.  Nutritional manipulation of fetal adipose tissue deposition and uncoupling protein 1 messenger RNA abundance in the sheep differential effects of timing and duration. Biol Reprod, 2004, 711 359-65.
  42. Clarke L, Heasman L, Juniper DT, and Symonds ME. Maternal nutrition in early-mid gestation and placental size in sheep. Br J Nutr, 1998, 79359-364.
  43. Clarke L, Buss DS, Juniper DT, et al. Adipose tissue development during early postnatal life in ewe-reared lambs. Exp Physiol, 1997, 826 1015-1027.
      注:文章中的參考文獻缺12

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