Corpening J W, Doerr J C, Kristal M B
Behavioral Neuroscience Program, Department of Psychology, Park Hall, State University of New York at Buffalo, Buffalo, NY 14260-4110, USA.
Physiol Behav. 2000;70(1-2):15-8. doi: 10.1016/s0031-9384(00)00244-4.
Ingestion by rats of rat placenta or amniotic fluid enhances opioid-mediated, or partly opioid-mediated, antinociception produced by morphine injection, vaginal or cervical stimulation, late pregnancy, and foot shock. This phenomenon is believed to be produced by a placental opioid-enhancing factor (POEF). Ingestion by rats of human or dolphin placenta has also been shown to enhance opioid antinociception, suggesting that POEF may be common to many mammalian species. We tested bovine amniotic fluid (BAF) for its capacity to enhance morphine antinociception in female Long-Evans rats, as determined by percentage change from baseline tail-flick latency in response to radiant heat, and we report that 0.50 mL BAF effectively enhanced morphine antinociception but did not by itself produce antinociception. The efficacy of POEF across species suggests that POEF may have been functionally (and structurally) conserved during evolution. Furthermore, the availability of POEF at parturition, as well as its ability to enhance pregnancy-mediated antinociception without disrupting maternal behavior, offers a tenable explanation for the long-debated ultimate causality of placentophagia.
给大鼠喂食大鼠胎盘或羊水，可增强由吗啡注射、阴道或宫颈刺激、妊娠后期及足部电击所产生的阿片类介导或部分阿片类介导的镇痛作用。这种现象被认为是由一种胎盘阿片增强因子（POEF）所致。已证实，给大鼠喂食人或海豚胎盘也可增强阿片类镇痛作用，这表明POEF可能在许多哺乳动物物种中都存在。我们通过对雌性Long-Evans大鼠进行辐射热刺激时尾巴甩动潜伏期相对于基线的变化百分比，来测试牛羊水（BAF）增强吗啡镇痛作用的能力，我们发现0.50 mL BAF可有效增强吗啡镇痛作用，但自身并不产生镇痛作用。POEF在不同物种间的有效性表明，POEF在进化过程中可能在功能（和结构）上得到了保留。此外，分娩时POEF的存在，以及其增强妊娠介导的镇痛作用而不干扰母体行为能力，为长期以来备受争议的食胎盘行为的最终因果关系提供了一个合理的解释。
