DiPirro Jean M, Kristal Mark B
Behavioral Neuroscience Program, Department of Psychology, University at Buffalo, Buffalo, NY 14260, USA.
Brain Res. 2004 Jul 16;1014(1-2):22-33. doi: 10.1016/j.brainres.2004.04.006.
Ingestion of placenta or amniotic fluid produces a dramatic enhancement of centrally mediated opioid antinociception in the rat. The present experiments investigated the role of each opioid receptor type (mu, delta, kappa) in the antinociception-modulating effects of Placental Opioid-Enhancing Factor (POEF-presumably the active substance). Antinociception was measured on a 52 degrees C hotplate in adult, female rats after they ingested placenta or control substance (1.0 g) and after they received an intracerebroventricular injection of a delta-specific ([D-Pen2,D-Pen5]enkephalin (DPDPE); 0, 30, 50, 62, or 70 nmol), mu-specific ([D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAMGO); 0, 0.21, 0.29, or 0.39 nmol), or kappa-specific (U-62066; spiradoline; 0, 100, 150, or 200 nmol) opioid receptor agonist. The results showed that ingestion of placenta potentiated delta- and kappa-opioid antinociception, but attenuated mu-opioid antinociception. This finding of POEF action as both opioid receptor-specific and complex provides an important basis for understanding the intrinsic pain-suppression mechanisms that are activated during parturition and modified by placentophagia, and important information for the possible use of POEF as an adjunct to opioids in pain management.
摄入胎盘或羊水可显著增强大鼠中枢介导的阿片类药物镇痛作用。本实验研究了每种阿片受体类型（μ、δ、κ）在胎盘阿片增强因子（推测为活性物质POEF）镇痛调节作用中的作用。在成年雌性大鼠摄入胎盘或对照物质（1.0 g）后，以及在它们接受脑室内注射δ特异性（[D-青霉胺2，D-青霉胺5]脑啡肽（DPDPE）；0、30、50、62或70 nmol）、μ特异性（[D-丙氨酸2，N-甲基苯丙氨酸4，甘氨酸5-醇]脑啡肽（DAMGO）；0、0.21、0.29或0.39 nmol）或κ特异性（U-62066；螺旋多林；0、100、150或200 nmol）阿片受体激动剂后，在52℃热板上测量镇痛作用。结果表明，摄入胎盘可增强δ和κ阿片类药物的镇痛作用，但减弱μ阿片类药物的镇痛作用。POEF作用具有阿片受体特异性和复杂性这一发现，为理解分娩期间激活并因食胎盘而改变的内在疼痛抑制机制提供了重要依据，也为POEF可能作为阿片类药物在疼痛管理中的辅助药物提供了重要信息。
