Department of Paediatrics, The Hospital for Sick Children, Toronto M5G 1X8, Ontario, Canada.
Department of Paediatrics and Physiology, The Hospital for Sick Children, Toronto M5G 1X8, Ontario, Canada.
World J Gastroenterol. 2021 Sep 7;27(33):5566-5574. doi: 10.3748/wjg.v27.i33.5566.
Oral intake is dependent on the gastric ability to accommodate the food bolus. Comparatively, neonates have a smaller gastric capacity than adults and this may limit the volume of their milk intake. Yet, we previously reported that the newborn rat gastric milk volume is greatest after birth and, when normalized to body weight, decreases with postnatal age. Such age-dependent changes are not the result of intake differences, but greater gastric accommodation and reduced emptying rate.
Hypothesizing that breastmilk-derived adiponectin is the factor regulating gastric accommodation in neonates, we comparatively evaluated its effects on the rat fundic muscle tone at different postnatal ages.
In freshly dispersed smooth muscle cells (SMC), we measured the adiponectin effect on the carbachol-induced length changes.
Adiponectin significantly reduced the carbachol-stimulated SMC shortening independently of age. In the presence of the inhibitor iberiotoxin, the adiponectin effect on SMC shortening was suppressed, suggesting that it is mediated large-conductance Ca sensitive K channel activation. Lastly, we comparatively measured the newborn rat gastric milk curd adiponectin content in one- and two-week-old rats and found a 50% lower value in the latter.
Adiponectin, a major component of breastmilk, downregulates fundic smooth muscle contraction potential, thus facilitating gastric volume accommodation. This rodent's adaptive response maximizes breastmilk intake volume after birth.
口服摄入依赖于胃容纳食物团的能力。相比之下，新生儿的胃容量比成人小，这可能限制了他们的牛奶摄入量。然而，我们之前的研究报告称，新生大鼠的胃内奶量在出生后最大，并且与体重相比，胃内奶量随出生后年龄的增长而减少。这种年龄依赖性的变化不是由于摄入差异，而是由于胃容纳增加和排空率降低所致。
假设母乳来源的脂联素是调节新生儿胃容纳的因素，我们比较评估了其对不同出生后年龄大鼠胃底肌肉张力的影响。
在新分散的平滑肌细胞（SMC）中，我们测量了脂联素对乙酰胆碱诱导的长度变化的影响。
脂联素独立于年龄显著减少了乙酰胆碱刺激的 SMC 缩短。在大电导钙敏感钾通道抑制剂 iberiotoxin 的存在下，脂联素对 SMC 缩短的作用被抑制，表明其是通过大电导钙敏感钾通道激活介导的。最后，我们比较测量了一至两周龄新生大鼠胃奶凝块中的脂联素含量，发现后者的含量低 50%。
脂联素是母乳的主要成分之一，可下调胃底平滑肌收缩潜能，从而促进胃容量容纳。这种啮齿动物的适应性反应最大限度地增加了出生后母乳的摄入量。
