Placenta ingestion enhances opiate analgesia in rats

Kristal, Mark B.; Thompson, Alexis C.; Grishkat, Holly L.

doi:10.1016/0031-9384(85)90127-1

Cited by 46 publications

(44 citation statements)

References 26 publications

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“…I, salinc-injecteu groups). Both the dose dependent efficacy anu the inability of BAF to produce anti nociception independent of opioid antinociception are con sistent with previous findings [4,[12][13][14]16,17,23,25].…”

Section: Discussionsupporting

confidence: 87%

“…Ingestion of placenta physiological characteristics presumably have been main or AF enhances the opioid, or partly opioid, antinociception tained (albeit with modification) or have independently con produced by the central action [4] of morphine sulfate (MS) verged, the result of which has been behavioral and mor injected peripherally [7,11,14,16,25], foot shock [16], vaginal phological parallelism among mammalian species. One or cervical stimulation [1,6,17,28], and late pregnancy [15], characteristic that is recognized in all pregnant eutherian and does so via gastric vagal afferents [22,26J.…”

Section: Introductionmentioning

confidence: 99%

“…Of particular interest in the receptors, but inhibits antinociception produced by activation comparative study of mammalian behavior is the fact that at of J.L opioid receptors [3,5,11], Ingestion of placenta or AF parturition, females of almost all eutherian species engage does not, however, affect morphine-induced hyperthermia [I J in placentophagia-ingestion of placenta and amniotic fluid or nonopioid antinociception [13,23], nor does it produce anti (AF) [9]. nociception by itself [4,[12][13][14]16,17,23,251. Because opioid The desire to understand the proximate and ultimate action is a prerequisite for the enhancing activity of ingested causes of placentophagia has inspired a variety of explana placenta and AF, Kristal et al r14] have named the enhancing tions for the phenomenon.…”

Section: Introductionmentioning

confidence: 99%

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Ingested bovine amniotic fluid enhances morphine antinociception in rats

Corpening

Doerr

Kristal

2000

Physiology & Behavior

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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 pla cental opioid-enhancing factor (POEF). Ingestion by rats of human or dolphin placenta has also been shown to enhance opioid antinoci ception, 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 re sponse to radiant heat, and we report that 0.50 mL BAF effectively enhanced morphine antinociception but did not by itself produce an tinociception. 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 with out disrupting maternal behavior, offers a tenable explanation for the long-debated ultimate causality of placentophagia.

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Section: Discussionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ingested bovine amniotic fluid enhances morphine antinociception in rats

Corpening

Doerr

Kristal

2000

Physiology & Behavior

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“…PLACENTA and amniotic fluid have been shown to contain a substance (POEF, for Placental Opioid-Enhancing Factor) that, when ingested, enhances existing opioid-mediated analgesia, as measured by tail-nick latency (TFL) in rats (6)(7)(8). Ingestion of these afterbirth substances in the absence of opiate-mediated analgesia, however, does not produce analgesia.…”

mentioning

confidence: 99%

Dose-dependent enhancement of morphine-induced analgesia by ingestion of amniotic fluid and placenta

Kristal

Abbott

Thompson

1988

Pharmacology Biochemistry and Behavior

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. Dose-dependent enhancement oJmorphine-induced analgesia by ingestion oj amniotic fluid and placenta. PHARMACOL BIOCHEM BEHAV 31(2) [351][352][353][354][355][356] 1988.-Ingestion of amniotic fluid and placenta by rats has been shown to enhance opioid-mediated analgesia. The present studies were designed to examine the effect of several doses and volumes of placenta and amniotic fluid on tail-flick latency in rats treated with 3 mg/kg morphine. The optimal dose of amniotic fluid was found to be 0.25 ml, although 0.50 and 1.0 ml also produced significant enhancement. Doses of 0.125 and 2 ml of amniotic fluid were ineffective, as was a dose of 0.25 ml diluted to 2 ml with saline. The optimal dose of placenta was found to be 1 placenta, although the resulting enhancement was not significantly greater than that produced by 0.25, 0.50, 2.0 or 4.0 placentas. Doses smaller than 0.25 placenta or larger than 4.0 placentas were ineffective. The most effective doses of amniotic fluid and placenta correspond to the amounts delivered with each pup during parturition.

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“…Placentophagia (ingestion of afterbirth material) occurs in most nonhuman and non-aquatic mammalian species at parturition (Kristal, 1980(Kristal, , 1991(Kristal, , 1998. Ingestion of placenta or amniotic fluid modulates opioid-mediated events: (a) it enhances opioid-induced hypoalgesia (Kristal et al, 1985(Kristal et al, , 1986a(Kristal et al, , 1986b whether the pain relief is produced by endogenous (Kristal et al, 1990a(Kristal et al, , 1990b(Kristal et al, , 1986a(Kristal et al, , 1986b or exogenous opioids (Kristal et al, 1985(Kristal et al, , 1986a(Kristal et al, , 1986b, (b) it does not affect nonopioid-induced hypoalgesia (Kristal et al, 1990a(Kristal et al, , 1990bRobinson-Vanderwerf et al, 1997), and (c) it does not produce hypoalgesia by itself (without the existence of an underlying opioid hypoalgesia) (Kristal, 1991(Kristal, , 1998. Furthermore, ingestion of placenta enhances δ-and κ-opioid-receptor-mediated hypoalgesia and attenuates μ-opioid-receptor-mediated hypoalgesia (DiPirro and Kristal, 2004), which is consistent with Gintzler's research (Gintzler, 1980;Gintzler and Liu, 2001) showing that the spinal mechanisms of periparturitional hypoalgesia (pregnancy-mediated analgesia) are mediated by δ-and κ-opioid receptors, but not by μ-opioid receptors (Gintzler and Liu, 2001).…”

Section: Introductionmentioning

confidence: 99%

Ingestion of amniotic fluid enhances the facilitative effect of VTA morphine on the onset of maternal behavior in virgin rats

et al. 2009

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Previous research has shown that injection of morphine into the ventral tegmental area (VTA) facilitates the onset of maternal behavior in virgin female rats, and injection of the opioid antagonist naltrexone into the VTA disrupts the onset of maternal behavior in parturient rats. Placentophagia -ingestion of placenta and amniotic fluid, usually at parturition -modifies central opioid processes. Ingestion of the active substance in placenta and amniotic fluid, Placental Opioid-Enhancing Factor (POEF), enhances the hypoalgesic effect of centrally administered morphine, and more specifically, enhances δ-and κ-opioidreceptor-mediated hypoalgesia and attenuates μ-opioid-receptor-mediated hypoalgesia. POEF (in placenta or amniotic fluid) ingestion does not, by itself, produce hypoalgesia. In the present study, we tested the hypothesis that ingestion of amniotic fluid enhances the facilitative effect of opioid activity (unilateral morphine injection) in the VTA on the rate of onset of maternal behavior. Virgin female Long-Evans rats were given one intra-VTA injection of morphine sulfate (0.0, 0.01, or 0.03 μg, in saline) and an orogastric infusion of 0.25 ml amniotic fluid or saline once each day of the first three days of the 10-day testing period. Subjects were continuously exposed to foster pups that were replaced every 12 h; replacement of pups was followed by a 15-min observation period. Maternal behavior latency was determined by the first of two consecutive tests wherein the subject displayed pup retrieval, pup licking in the nest, and crouching over all foster pups, during the 15-min observation. We confirmed the previous finding that the VTA injection, alone, of 0.03 μg IntroductionRats at parturition show an almost immediate onset of appropriate maternal behavior. In contrast, the onset of maternal behavior in virgin rats that are continuously exposed to relatively constant-age foster pups (a procedure referred to as "concaveation", i.e., "with pups") is slow to appear, and is usually measured as the latency, in days, to the appearance of B R A I N R E S E A R C H 1 2 6 1 ( 2 0 0 9 ) 2 9 -3 6 ⁎ Corresponding author.

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Placenta ingestion enhances opiate analgesia in rats

Cited by 46 publications

References 26 publications

Ingested bovine amniotic fluid enhances morphine antinociception in rats

Ingested bovine amniotic fluid enhances morphine antinociception in rats

Dose-dependent enhancement of morphine-induced analgesia by ingestion of amniotic fluid and placenta

Ingestion of amniotic fluid enhances the facilitative effect of VTA morphine on the onset of maternal behavior in virgin rats

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