El-Haddad Mostafa A, Ismail Yaser, Guerra Catalina, Day Linda, Ross Michael G
Perinatal Research Laboratories, Harbor/UCLA Medical Center, University of California-Los Angeles School of Medicine, 1124 W. Carson Street, RB-1, Torrance, CA 90502, USA.
Am J Obstet Gynecol. 2002 Oct;187(4):898-901. doi: 10.1067/mob.2002.127722.
Dipsogen-mediated ingestion matures acutely in late gestation because the preterm fetus may demonstrate absent responses to putative dipsogens. Although central appetite-mediated ingestive behavior is functional near term, it is unknown whether peripheral mechanisms for stimulation of appetite also are functional. In the adult, sweet taste stimulates and potentiates ingestive behavior. We sought to determine whether oropharyngeal sucrose exposure stimulates ingestive behavior in the near-term ovine fetus.
Time-dated pregnant ewes with near-term singleton fetuses (n = 6) were chronically prepared with fetal vascular and sublingual catheters and esophageal electromyogram electrodes and studied at 129 +/- 1 days of gestation. After an initial 2-hour baseline period, successive solutions of distilled water and 2.5%, 10%, and 40% sucrose were infused sublingually (0.25 mL/min), each for 2 hours. Maternal and fetal arterial blood samples were drawn at timed intervals.
During the basal period, fetal swallowing averaged 0.9 +/- 0.1 swallows per minute. Swallowing did not change in response to distilled water (0.9 +/- 0.2 swallows per minute) but significantly increased after sublingual infusion of 2.5% sucrose (1.3 +/- 0.1 swallows per minute), 10% sucrose (1.8 +/- 0.1 swallows per minute), and 40% sucrose (1.3 +/- 0.1 swallows per minute, P =.001). There were no significant changes in other fetal or maternal parameters.
The stimulation of fetal swallowing in response to sublingual sucrose infusion suggests that taste-mediated ingestive behavior is functional in the near-term fetus and that both central and systemic appetite mechanisms are intact near term. Fetal swallowing increased in response to an increase in sucrose concentration to peak at 10% and then decreased with further rises in concentration, possibly mediated by aversive fetal reaction to a high-intensity sucrose concentration.
由于早产胎儿可能对假定的致渴剂无反应，致渴剂介导的摄食行为在妊娠晚期急性成熟。尽管中枢食欲介导的摄食行为在足月时起作用，但刺激食欲的外周机制是否也起作用尚不清楚。在成年人中，甜味刺激并增强摄食行为。我们试图确定口咽蔗糖暴露是否能刺激足月绵羊胎儿的摄食行为。
对怀有足月单胎胎儿（n = 6）的孕羊进行长期准备，植入胎儿血管和舌下导管以及食管肌电图电极，并在妊娠129±1天时进行研究。在最初 的2小时基线期后，依次经舌下输注蒸馏水以及2.5%、10%和40%的蔗糖溶液（0.25 mL/分钟），每种溶液输注2小时。定时采集母羊和胎儿的动脉血样。
在基础期，胎儿吞咽平均每分钟0.9±0.1次。对蒸馏水（每分钟0.9±0.2次吞咽）无反应，但经舌下输注2.5%蔗糖（每分钟1.3±0.1次吞咽）、10%蔗糖（每分钟1.8±0.1次吞咽）和40%蔗糖（每分钟1.3±0.1次吞咽，P = 0.001）后，吞咽显著增加。其他胎儿或母羊参数无显著变化。
舌下输注蔗糖刺激胎儿吞咽表明，味觉介导的摄食行为在足月胎儿中起作用，并且中枢和全身食欲机制在足月时均完好无损。胎儿吞咽随着蔗糖浓度的增加而增加，在10%时达到峰值，然后随着浓度进一步升高而下降，这可能是由胎儿对高强度蔗糖浓度的厌恶反应介导的。
