Iwasaki H, Collins J G, Saito Y, Omote T, Namiki A
Department of Anesthesiology, Sapporo Medical College & Hospital.
Masui. 1990 Oct;39(10):1372-6.
Activation of an endogenous opioid system has been associated with an elevation in pain threshold during late pregnancy and the early postpartum period in rats. It is well established that endogenous opiates are involved in the physiological regulation on prolactin secretion. This study examined the influence of lactation on pregnancy-induced analgesia during the early postpartum period in rats. Three tests (colorectal distension, tail-flick and hot-plate) were used to assess each animal's response to painful stimuli. After determining pregnant baseline values, one group of rats (lactating, n = 21) were mated and retested on Day 7 and 21 of gestation and 1, 3, 5, 7 and 14 days after parturition. A non-lactating group of animals (n = 14) whose pups were removed immediately after delivery was tested in the same manner. On Day 21 of gestation significantly higher thresholds and longer latencies were observed. On Day 1 and 3 in both lactating and non-lactating rats, the values were still elevated. No significant difference was observed during the early postpartum period between the two groups. This study confirms the existence, in rats, of pregnancy-induced analgesia late in pregnancy and the early postpartum period. The analgesia during the early postpartum period is not influenced by lactation.
内源性阿片系统的激活与大鼠妊娠晚期和产后早期痛阈升高有关。众所周知，内源性阿片参与催乳素分泌的生理调节。本研究考察了泌乳对大鼠产后早期妊娠诱导镇痛的影响。采用三种测试（结直肠扩张、甩尾和热板）评估每只动物对疼痛刺激的反应。在确定妊娠基线值后，一组大鼠（泌乳组，n = 21）交配，并在妊娠第7天和第21天以及产后1、3、5、7和14天重新测试。另一组非泌乳动物（n = 14）在分娩后立即将幼崽移走，并以相同方式进行测试。在妊娠第21天观察到阈值显著更高，潜伏期更长。在泌乳和非泌乳大鼠的第1天和第3天，这些值仍然升高。在产后早期，两组之间未观察到显著差异。本研究证实了大鼠在妊娠晚期和产后早期存在妊娠诱导镇痛。产后早期的镇痛不受泌乳影响。
