肠外营养脂质组成对新生仔猪视网膜功能的影响

　　伴有短肠综合征、肠功能障碍的早产儿在生长发育及神经发育的重要时期容易罹患肠衰竭相关肝病（IFALD）、早产儿视网膜病变及视觉损害。已有研究证实二十二碳六烯酸（DHA）及花生四烯酸（AA）对于新生儿神经及视网膜发育具有不可或缺的作用。然而通常PN中所含的大豆油（SO）缺乏DHA（0%）和AA（0.1%），而鱼油（FO）中包含更多的DHA（12%）和AA（2%）。

　　加拿大阿尔伯塔大学、多伦多大学、多伦多儿童医院将2～5天的新生猪仔随机分组，分别给予SO（n=4）和FO（n=4）肠外营养14天后，用视网膜电流图（ERG）检测视网膜功能。

　　结果发现，FO组与SO组相比，暗适应α波幅降低（P＜0.001），隐含期延长。

　　因此，PN添加富含DHA和AA的FO脂肪乳与SO脂肪乳相比，反而不能改善视网膜功能。

JPEN J Parenter Enteral Nutr. 2017;41(2):270.

Impact of parenteral lipid composition when delivered at restricted doses on retinal function of neonatal piglets.

Marihan Lansing; Justine Turner; Pamela R. Wizzard; David W. Lim; Catherine J. Field; Yves Sauvé; Paul W. Wales.

University of Alberta, Edmonton, Alberta, Canada; Hospital for Sick Children and Research Institute, University of Toronto, Toronto, Ontario, Canada.

PURPOSE: Preterm neonates and infants with short bowel syndrome and intestinal failure depend on parenteral nutrition (PN) therapy during a critical period of growth and neurological development. Furthermore, preterm infants are at risk of developing intestinal failure-associated liver disease (IFALD), retinopathy of prematurity, and visual impairment. It is established that docosahexaenoic acid (DHA) and arachidonic acid (AA) are essential for neonatal neural and retinal development. However, currently available soybean oil-based lipid emulsions (SO; Intralipid) are deficient in DHA (0%) and AA (0.1%). Current strategies to reduce the risk of IFALD, such as lipid dose restriction, may further increase the risk of DHA and AA dietary insufficiency. We sought to explore whether a fish oil-based lipid emulsion (FO, Omegaven), used to prevent and treat IFALD, would better support neonatal retinal development and function, as it contains substantially more DHA (12%) and AA (2%). We compared the impact of low-dose SO vs FO on retinal function (electroretinography/ERG) and fatty acid content in neonatal piglets given PN.

METHODS: Neonatal piglets (2-5 days old) were randomly allocated to 2 treatment groups: SO (n = 4) and FO (n = 4). A sow-reared piglet group (REF, n = 7) provided normative reference data. PN was delivered for 14 days and lipid was dosed at 50% of normal requirements for growing piglets: 5 g/kg/d, equivalent to 1 g/kg/d in human infants. Retinal function was assessed by ERG on day 14, for both light (pure cone-driven responses) and dark adaptation (rod-driven responses), and then retinas were harvested for quantification of fatty acid content. The responses to varying light intensity stimuli were measured as amplitude (a-wave and b-wave) as well as the time to respond (implicit time). Data were analyzed by 2-way analysis of variance (light intensity × diet treatment) with Bonferroni post hoc correction; significance set at P < .05.

RESULTS: Over multiple levels of light stimulation, FO treatment, as compared with SO treatment, significantly diminished dark-adaptation (a-wave) amplitude (P < .001), while implicit times were increased (P = .036). Similarly, over multiple levels of stimulation, light adaptation (a-wave and b-wave) amplitudes were both diminished given FO vs SO treatment (P < .001). At all light intensity levels tested, ERG variables were consistently more similar to the REF in SO-treated piglets as compared with FO-treated piglets. DHA content was not different between PN groups (FO, 14.6% vs SO, 12.4%; P = .25; REF, 10%-13%). However, retinal AA was reduced given FO treatment compared with SO treatment (FO, 6.0% vs SO, 8.0%; P = .001; REF, 7%-8%).

CONCLUSIONS: The provision of low-dose fish oil-based lipid emulsions, rich in AA and DHA, paradoxically did not optimize retinal function in comparison to equivalently dosed soybean oil-based lipid emulsions, deficient in AA and DHA. One explanation might be the reduced enrichment of AA in the retina given FO treatment. Future research is required to optimize amounts of parenteral AA and DHA required for retinal development in preterm infants with intestinal failure. Given similarities in fatty acid composition between the brain and the retina, such research will have important implications for neurological outcomes beyond retinal function.

FINANCIAL SUPPORT: Parenteral lipids were provided in kind by Fresenius Kabi.

DOI: 10.1177/0148607116686023