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Cited by 60Endometriosis Research and TreatmentPain Mechanisms and TreatmentsPain Management and Treatment

Sprouted Innervation into Uterine Transplants Contributes to the Development of Hyperalgesia in a Rat Model of Endometriosis

Open access
McAllister, Stacy L., Dmitrieva, Natalia, Berkley, Karen J.·2012·PLoS ONE
DOI 10.1371/journal.pone.0031758PMC PMC3283674
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Abstract

Endometriosis is an enigmatic painful disorder whose pain symptoms remain difficult to alleviate in large part because the disorder is defined by extrauteral endometrial growths whose contribution to pain is poorly understood. A rat model (ENDO) involves autotransplanting on abdominal arteries uterine segments that grow into vascularized cysts that become innervated with sensory and sympathetic fibers. ENDO rats exhibit vaginal hyperalgesia. We used behavioral, physiological, and immunohistochemical methods to test the hypothesis that cyst innervation contributes to the development of this hyperalgesia after transplant. Rudimentary sensory and sympathetic innervation appeared in the cysts at two weeks, sprouted further and more densely into the cyst wall by four weeks, and matured by six weeks post-transplant. Sensory fibers became abnormally functionally active between two and three weeks post-transplant, remaining active thereafter. Vaginal hyperalgesia became significant between four and five weeks post-transplant, and stabilized after six to eight weeks. Removing cysts before they acquired functional innervation prevented vaginal hyperalgesia from developing, whereas sham cyst removal did not. Thus, abnormally-active innervation of ectopic growths occurs before hyperalgesia develops, supporting the hypothesis. These findings suggest that painful endometriosis can be classified as a mixed inflammatory/neuropathic pain condition, which opens new avenues for pain relief. The findings also have implications beyond endometriosis by suggesting that functionality of any transplanted tissue can be influenced by the innervation it acquires.

AI snapshot

Written from the paper’s full text.

TL;DR

In a rat endometriosis model, sensory and sympathetic nerve fibers sprout into uterine transplants, become functionally active around three weeks post-transplant, and precede the development of vaginal hyperalgesia at four to five weeks. Removing cysts before they acquire functional innervation prevents hyperalgesia, supporting painful endometriosis as a mixed inflammatory/neuropathic pain condition.

Key findings

  • Cyst innervation appeared at two weeks post-transplant, sprouted and densely populated the cyst wall by four weeks, and attained a mature appearance by six weeks; no sensory or sympathetic neurites were observed inside cysts at one week.
  • Sensory fibers became abnormally functionally active approximately three weeks post-transplant: Evans Blue extravasation differed significantly between intact and denervated cysts from three through ten weeks, while denervated cysts showed no significant change over time (F5,65 = 0.77, P = 0.57).
  • Vaginal hyperalgesia did not differ significantly from baseline at one to three weeks, became significant by five weeks, and stabilized after six weeks (overall ANOVA F10,72 = 4.37, p<0.001).
  • Removing cysts before functional innervation prevented hyperalgesia (overall n = 8; F1,14 = 0.68, P = 0.80), whereas sham cyst removal did not (n = 4; F1,6 = 27.1, P = 0.002).

Methods

  • Female Sprague-Dawley rats (175–225 g) underwent autotransplantation of four approximately 2 mm × 2 mm uterine horn pieces onto mesenteric arteries to create the ENDO model; behavioral testing used vaginal distention escape responses, with data shown from proestrus.
  • Immunohistochemistry labeled sensory C-fibers with CGRP and sympathetic fibers with VMAT2 in cysts harvested at 2, 3, 4, 6, or 10 weeks post-transplant (n = 3–5 rats per survival time).
  • Neurogenic activity was assessed by Evans Blue dye extravasation in intact versus denervated cysts at 1, 2, 3, 4, 6, or 10 weeks (n = 8–12 per group), and cyst removal or sham removal was performed 1–4 weeks post-transplant; analyses used AUC calculations, ANOVA, post-hoc LSD tests, and unpaired t-tests.

Limitations

  • The paper states that no clinical data yet address neural sprouting into ectopic growths during early stages of pain development, although evidence in women supports neural modulation once endometriosis is established.
  • The 10-week Evans Blue data were only from rats in metestrus, not proestrus, as stated by the authors.
  • Some groups were small (e.g., immunostaining n = 3–5 per survival time; cyst-removal subgroups n = 3; sham removal n = 4), and one of three rats in the 4-week cyst-removal group still exhibited hyperalgesia.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1371/journal.pone.0031758

Cites

45 of 45 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 46 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    There were no significant differences over time after transplant surgery in Evans Blue dye extravasation in denervated cysts.

    “whereas there was a gradual increase in dye extravasation in the intact cysts, there were no significant differences over time after transplant surgery in the denervated cysts (F5,65 = 0.77, P = 0.57).”
    Quote in the paperSubstantial claim
  • Findingown data

    Sensory fibers in cysts became abnormally active (produced neurogenic activity) approximately three weeks after surgery.

    “In other words, sensory fibers became abnormally active (produced neurogenic activity) approximately three weeks after surgery.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The denervation procedure used in the Evans Blue experiments completely eliminates the cysts' sensory and sympathetic innervation.
  • Findingown data

    By four weeks post-transplant, sensory and sympathetic neurites were no longer punctate, but branched and looked similar to fibers in established cysts.

    “By four weeks post-transplant, the characteristics of both sensory and sympathetic neurites changed their appearance so that they were no longer punctate, but instead branched and looked similar to fibers in established cysts.”
    Quote in the paperSubstantial claim
  • Findingown data

    From one to three weeks after transplant surgery, the probability of escape responses to vaginal distention did not differ significantly from baseline in ENDO rats.

    “From one to three weeks after transplant surgery, the probability of escape responses to vaginal distention did not differ significantly from baseline responses; i.e., no significant changes from baseline nociception had occurred (Fig. 1A).”
    Quote in the paperSubstantial claim
  • Findingcitation

    Fiber characteristics at six weeks post-transplant were virtually identical to those previously observed in established cysts.

    “Overall, fiber characteristics at six weeks post-transplant were virtually identical to those previously observed in established cysts [10].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [10] KJ Berkley, 2004, Innervation of ectopic endometrium in a rat model of endometriosis., Proc Natl Acad Sci USA source

      Not checked in the free run.

  • May combine two claims. 22
  • Classified as probably not a substantial claim. 20

  • May combine two claims.

    Findingown data

    By four weeks post-transplant, fiber density increased dramatically and populated the entire cyst wall, including myometrial and endothelial layers.

    “In addition, the fiber density increased dramatically and populated the entire cyst wall, including myometrial and endothelial layers.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    By six weeks after transplant, the appearance of both types of fibers was similar to that at four weeks, with a slight increase in density and similar to that at ten weeks post-transplant.

    “By six weeks after transplant, the appearance of both types of fibers was similar to that at four weeks, with a slight increase in density and similar to that at ten weeks post-transplant.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    By four weeks after transplant surgery, escape responses to vaginal distention tended to differ from baseline, becoming significantly different by five weeks.

    “By four weeks after transplant surgery, however, responses tended to differ from baseline, becoming significantly different by five weeks.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Evans Blue dye extravasation into intact cysts increased progressively after transplant surgery and became significantly different at four weeks compared with one week.

    “EB dye extravasation into intact cysts increased progressively after transplant surgery (F5,67 = 2.90, p = 0.02) and became significantly different at four weeks post-transplant surgery compared with one week post-transplant (p<0.05).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Vaginal hyperalgesia became significant between four and five weeks post-transplant and stabilized after six to eight weeks.

    “Vaginal hyperalgesia became significant between four and five weeks post-transplant, and stabilized after six to eight weeks.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Differences in Evans Blue dye extravasation between intact and denervated cysts became significant three weeks after transplant surgery and remained significant through ten weeks.

    “The differences between the intact and denervated cysts became significant three weeks after transplant surgery, and remained that way through ten weeks after transplant.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The denervation procedure used in the Evans Blue experiments completely eliminates the cysts' sensory and sympathetic innervation.

  • May combine two claims.

    Findingown data

    Sensory and sympathetic neurites first appeared inside cysts two weeks post-transplant; none were observed inside cysts harvested one week after transplant.

    “Immunofluorescence staining with antibodies to CGRP and VMAT2 revealed that both sensory and sympathetic neurites first appeared inside cysts two weeks post-transplant surgery; i.e., none were observed inside cysts harvested one week after transplant.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Sham cyst removal from 2-4 weeks post-transplant does not prevent hyperalgesia; significant vaginal hyperalgesia develops in all rats.

    “In contrast, when a sham cyst-removal surgery was performed from 2–4 weeks post-transplant time in a different group of rats, significant vaginal hyperalgesia developed in all rats regardless of when the sham-cyst removal surgery had been done (Fig. 3D, n = 4; [F1,6 = 27.1, P = 0.002]).”
    • Also stated in: § Removing cysts before cyst innervation becomes active, but not sham cyst removal, prevents subsequent hyperalgesia from developing · plain
      “In contrast, after sham-cyst removal, regardless of when the surgery is performed relative to the innervation (either 2 or 4 weeks after transplant), hyperalgesia develops in all rats (n = 4).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the second behavioral study, the two-way ANOVA of AUC values (surgical group, test period) was significant (F3,20 = 10.02, p<0.001), with significant effects of test period (p<0.001), surgical group (p = 0.028), and the interaction between test period and surgical group (p = 0.001).

    “AUC values were statistically analyzed by a two-way ANOVA (surgical group, test period), which was also significant (F3,20 = 10.02, p<0.001), with significant effects of test period (p<0.001), surgical group (p = 0.028), and the interaction between test period and surgical group (p = 0.001).”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Findingown data

    The two-way ANOVA for Evans Blue extravasation data was significant (F11,120 = 2.44, p = 0.009).

    “Because a two-way ANOVA was significant (F11,120 = 2.44, p = 0.009), data were analyzed by post-hoc unpaired t-tests, with significance set at p≤0.05.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the second behavioral study, the three-way repeated measures ANOVA (distention volume, test period, cyst surgery type) was significant (F31,160 = 150.52, p<0.001), with significant effects of volume, pre- versus post-transplant test period, surgical group, and all interactions.

    “These data were statistically analyzed by a three-way repeated measure ANOVA (distention volume, test period, cyst surgery type), which was significant (F31,160 = 150.52, p<0.001), with significant (p<0.05) effects of volume, pre- versus post-transplant test period, surgical group, and all interactions (volume*test period; volume*surgery group; test period*surgery group, and volume*test period*sur”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Previous and current results indicate that there is a continuous and changing role of sensory and sympathetic innervation of the cysts: initially contributing to development of transplant-induced vaginal hyperalgesia, later contributing to modulation of its severity.

    “Together, these previous and our current results indicate that there is a continuous and, importantly, a changing role of sensory and sympathetic innervation of the cysts. Initially the innervation contributes to the development of transplant-induced vaginal hyperalgesia. Later, after the innervation is established, the innervation contributes to modulation of its severity.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    Activity in sympathetic fibers can also contribute to Evans Blue dye extravasation.

    “and that activity in sympathetic fibers can also contribute [14].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [14] PG Green, 1993, Further substantiation of a significant role for the sympathetic nervous system in inflammation., Neuroscience source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Sprouting is known to be associated with an increase in the background and evoked activity of these fibers; fibers that develop sprouts become sensitized, which contributes to protein extravasation.

    “Such sprouting is known to be associated with an increase in the background and evoked activity of these fibers; that is, fibers that develop sprouts become sensitized [17], [18], which contributes to protein extravasation [13].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [17] GF Gebhart, 1999, Peripheral contributions to visceral hyperalgesia., Can J Gastroenterol source

      Not checked in the free run.

    • cites [18] W Jänig, 1996, Interactions of sympathetic and primary afferent neurons following nerve injury and tissue trauma., Prog Brain Res

      Not checked in the free run.

    • cites [13] H Sann, 1998, Efferent functions of C-fiber nociceptors., Z Rheumatol source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Activity of C-fibers produces the neurogenic contribution to Evans Blue dye extravasation.

    “This method relies on the fact that activity of C-fibers produces the neurogenic contribution to EB extravasation [13]”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [13] H Sann, 1998, Efferent functions of C-fiber nociceptors., Z Rheumatol source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Removing cysts before they acquire functional innervation prevents hyperalgesia, whereas sham surgery does not.

    “Finally, removing the cysts before they acquire functional innervation prevents the hyperalgesia from developing, whereas a sham surgery does not.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    The sequence of events after transplant surgery is that cysts acquire rudimentary sensory and sympathetic innervation at two weeks, this innervation becomes functional at three weeks, and hyperalgesia becomes significant by four to five weeks.

    “Our studies show that a three-part sequence of events occurs after transplant surgery in the rat model. Initially, two weeks after transplant, the endometrial cysts acquire a rudimentary sensory and sympathetic innervation. A week later, three weeks post-transplant, this abnormal innervation becomes functional; i.e., it is capable of contributing to neurogenic inflammation. By four to five weeks,”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Increased nociceptive activity produces changes in the excitability of spinal neurons (central sensitization), which can expand from spinal segments where the fibers enter to more remote regions.

    “This increased nociceptive activity in turn produces changes in the excitability of spinal neurons, a phenomenon called central sensitization [19], [20], which can expand from spinal segments where the fibers enter to more remote regions [21].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [19] CJ Woolf, 1983, Evidence for a central component of post-injury pain hypersensitivity., Nature source

      Not checked in the free run.

    • cites [20] CJ Woolf, 2011, Central sensitization: implications for the diagnosis and treatment of pain., Pain source

      Not checked in the free run.

    • cites [21] JB Frøkjaer, 2005, An experimental study of viscero-visceral hyperalgesia using an ultrasound-based multimodal sensory testing approach., Pain source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In the rat model, autotransplanting uterine segments on abdominal arteries produces vascularized cysts that become innervated with sensory and sympathetic fibers.

    “A rat model of endometriosis is created by autotransplanting on abdominal arteries small pieces of uterus (ENDO). These transplants become vascularized and form cysts [6].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [6] MW Vernon, 1985, Studies on the surgical induction of endometriosis in the rat., Fertil Steril source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    After cysts stabilize (>8 weeks post-transplant), vaginal nociception varies with estrous stage, with hyperalgesia present in proestrus but absent the next day in estrus.

    “Thus, it was found that, after the cysts have stabilized (i.e., more than 8 weeks post-transplant), vaginal nociception varies with estrous stage, with hyperalgesia present in proestrus but absent the next day in estrus [7].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [7] A Cason, 2003, Estrous changes in vaginal nociception in a rat model of endometriosis., Horm Behav source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationreasoning

    One immediate consequence of reframing endometriosis as a neuropathic/inflammatory pain condition would be to reinforce the urgency of developing strategies for earlier diagnosis of endometriosis as well as treatment of its associated pain before that pain can become chronic and other painful co-morbid conditions arise.

    “Thus, one immediate consequence of reframing endometriosis as a neuropathic/inflammatory pain condition would be to reinforce the urgency of developing strategies for earlier diagnosis of endometriosis [30], [31] as well as treatment of its associated pain (e.g., dysmenorrhea) before that pain can become chronic and other painful co-morbid conditions arise.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [30] KJ Berkley, 2011, Don&apos;t dismiss dysmenorrhea! Pain

      Not checked in the free run.

    • cites [31] KE May, 2011, Endometrial alterations in endometriosis: a systematic review of putative biomarkers., Hum Reprod Update source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Debate about the importance of re-innervation for healthy organ functioning continues, but is generally supportive.

    “Debate about the importance of this re-innervation for healthy organ functioning continues, but is generally supportive [38].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [38] B Geny, 2008, Last word on Point:Counterpoint: cardiac denervation does/does not play a major role in exercise limitation after heart transplantation., J Appl Physiol source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The severity of vaginal hyperalgesia or referred muscle hyperalgesia is greatest during proestrus.

    “Here, we show data obtained during proestrus, the stage in which the severity of vaginal hyperalgesia or referred muscle hyperalgesia is greatest [7]–[9].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [7]–[9]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Moderate-to-severe dysmenorrhea is associated with significant brain dysfunction and abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis (a reduction in cortisol levels).

    “Recent brain imaging studies have shown that moderate-to-severe dysmenorrhea is associated with significant brain dysfunction and abnormalities in the hypothalamic–pituitary–adrenal (HPA) axis (a reduction in cortisol levels) [3], [27]–[30].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [3] P Stratton, 2011, Chronic pelvic pain and endometriosis: translational evidence of the relationship and implications., Hum Reprod Update source

      Not checked in the free run.

    • cites [27]–[30]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The results have relevance to tissue/organ transplantation.

    “Besides endometriosis, our results have relevance to another, seemingly unrelated clinical situation: tissue/organ transplantation.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: All donor tissues and organs are denervated before transplantation.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    All rats maintained regular four-day estrous cycles throughout the study.

    “All rats maintained regular four-day estrous cycles throughout the study.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationreasoning

    Such classification would also bring under consideration how therapeutic strategies now in use or under development for neuropathic pain might be applied to painful or potentially painful endometriosis.

    “Such classification would also bring under consideration how therapeutic strategies now in use or under development for neuropathic pain might be applied to painful or potentially painful endometriosis [32], [33].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [32] AB O'Connor, 2009, Treatment of neuropathic pain: an overview of recent guidelines., Am J Med source

      Not checked in the free run.

    • cites [33] O de Leon-Casasola, 2011, New developments in the treatment algorithm for peripheral neuropathic pain., Pain Med source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The issue of whether chronic pain or co-morbidity develops after transplant is complicated by the lifetime cocktail of neurotoxic immunosuppressant and other drugs that patients must take.

    “The issue of whether either chronic pain or co-morbidity develops after transplant, is, however, complicated by the lifetime cocktail of neurotoxic immunosuppressant and other drugs that patients must take [41].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] M Senzolo, 2009, Neurologic complications after solid organ transplantation., Transpl Int source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Most studies in humans of re-innervation of transplanted organs generally indicate that there is limited sympathetic fiber re-innervation by a year or more after transplant.

    “Most studies in humans of re-innervation of transplanted organs (necessarily allogenic) generally indicate that there is limited sympathetic fiber re-innervation by a year or more after transplant [36], [37].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [36] RF Wilson, 1991, Evidence for structural sympathetic reinnervation after orthotopic cardiac transplantation in humans., Circulation source

      Not checked in the free run.

    • cites [37] AP Dhillon, 1992, Immunohistochemical studies on the innervation of human transplanted liver., J Pathol source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Innervation of the healthy uterus undergoes anatomical changes during the ovarian cycle and significant changes during pregnancy.

    “Furthermore, others have shown in both rodents and humans that innervation of the healthy uterus also undergoes anatomical changes during the ovarian cycle as well as significant changes during pregnancy [42].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [42] C Latini, 2008, Remodeling of uterine innervation., Cell Tissue Res source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Central sensitization can eventually become self-sustained and independent of peripheral pathology so that, in some women with endometriosis, surgical removal of the ectopic growths would fail to alleviate pain.

    “Importantly, central sensitization can eventually become self-sustained and independent of peripheral pathology so that, in some women with endometriosis, surgical removal of the ectopic growths would fail to alleviate pain [3].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] P Stratton, 2011, Chronic pelvic pain and endometriosis: translational evidence of the relationship and implications., Hum Reprod Update source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Testing sessions in each of the two assessment periods included at least 3 days in each estrous stage.

    “Testing sessions in each of the two assessment periods included at least 3 days in each estrous stage.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Sensory fibers and postganglionic neurons for the sympathetic fibers that sprout into the cysts are located in the splanchnic nerve and coeliac ganglion, respectively.

    “Previously, we observed that sensory fibers and postganglionic neurons for the sympathetic fibers that sprout into the cysts are located in the splanchnic nerve and coeliac ganglion, respectively [45].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [45] N Dmitrieva, 2010, Endocannabinoid involvement in endometriosis., Pain source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    A neuropathic classification has recently been effectively applied to pain associated with visceral disorders such as pancreatitis, in which abnormal nerve sprouting, like that associated with endometriosis, plays a substantial role in the development of pain.

    “Thus, for example, a neuropathic classification has recently been effectively applied to pain associated with visceral disorders such as pancreatitis, in which abnormal nerve sprouting, like that associated with endometriosis, plays a substantial role in the development of pain [23].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [23] IE Demir, 2011, Pain mechanisms in chronic pancreatitis: of a master and his fire., Langenbecks Arch Surg source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Some findings suggest limited sensory fiber re-innervation, as evidenced by pain provoked by cardiac ischemia in heart transplant patients or lobeline injections in lung transplant patients.

    “Some findings also suggest limited sensory fiber re-innervation, as evidenced by the fact that pain can be provoked by cardiac ischemia in heart transplant patients [39] or lobeline injections in lung transplant patients [40].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [39] RP Stark, 1991, Chest pain in cardiac-transplant recipients. Evidence of sensory reinnervation after cardiac transplantation., N Engl J Med source

      Not checked in the free run.

    • cites [40] JE Butler, 2001, Changes in respiratory sensations induced by lobeline after human bilateral lung transplantation., J Physiol source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Rats in metestrus, like those in proestrus, evidence vaginal hyperalgesia; the biggest difference in severity of hyperalgesia is between proestrus and estrus.

    “because rats in metestrus, like those in proestrus, evidence vaginal hyperalgesia; i.e., the biggest difference in severity of hyperalgesia is between proestrus and estrus [7].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [7] A Cason, 2003, Estrous changes in vaginal nociception in a rat model of endometriosis., Horm Behav source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Negative controls for immunostaining were routinely performed and showed no immunostaining of nerve fibers.

    “Negative controls were routinely performed for each immunostaining run; they included omission of the primary or the secondary antibody or both. No immunostaining of nerve fibers was evident in these controls.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Some evidence exists for re-innervation of the auto-transplanted heart and syngeneically-transplanted kidney in experimental animals.

    “Some evidence exists for re-innervation of the auto-transplanted heart and syngeneically-transplanted kidney in experimental animals [34], [35].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [34] Y Kondo, 1972, Autonomic reinnervation of cardiac transplants: further observations in dogs and rhesus monkeys., Ann Surg source

      Not checked in the free run.

    • cites [35] O Grisk, 2001, Sympathetic reinnervation of rat kidney grafts., Transplantation source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Visceral C-fibers that are sensitized in association with an initial inflammation may become a source of neuropathic pain.

    “it has been argued that visceral C-fibers that are sensitized in association with an initial inflammation “may become a source of neuropathic pain” [22].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [22] SK Sauer, 2009, Inflammation and hypersensitivity in the context of the sensory functions of axonal membranes: what are the molecular mechanisms?, Dig Dis source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable).

    Interpretationreasoning

    The findings suggest that painful endometriosis in women, already considered an inflammatory condition, might benefit from being additionally classified as a neuropathic pain condition.

    “Insofar as data in rats can help us understand mechanisms that contribute to pain in women with endometriosis (see table IV in ref. 3), our findings here suggest that painful endometriosis in women, already considered an inflammatory condition [3], might benefit from being additionally classified as a neuropathic pain condition.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] P Stratton, 2011, Chronic pelvic pain and endometriosis: translational evidence of the relationship and implications., Hum Reprod Update source

      Not checked in the free run.

40 of 40

  • The paper relies on this without support.

    All donor tissues and organs are denervated before transplantation.

    “Due to their removal from the donor, all donor tissues and organs are denervated before transplantation.”

  • The paper relies on this without support.

    The denervation procedure used in the Evans Blue experiments completely eliminates the cysts' sensory and sympathetic innervation.

    “the extravasation in intact cysts was compared with the extravasation in cysts that had been denervated before the dye was injected.”
2 of 2

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Figure 1 reports a different behavioral sample size

    Major

    The Figure 1 caption gives n = 18, but the methods say the first behavioral study, which assessed the same time course, used 10 rats.

  • Early cyst-removal group is reported as both three and five rats

    Minor

    The Results text assigns three rats to cyst removal at two weeks or less, whereas the caption for that group reports five.

2 of 2

Cites

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Authors
McAllister, S. L., Dmitrieva, N., & Berkley, K. J.
Affiliations
Florida State University (US)
Corresponding author
Berkley, Karen J.
ORCID
Venue
PLoS ONE
Publisher
Public Library of Science (PLoS)
Published
2012-02-21
Volume
7
Issue
2
Pages
e31758
ISSN
1932-6203 (ISSN-L)
DOI
10.1371/journal.pone.0031758
PMC
PMC3283674
OpenAlex
W2056634842
Semantic Scholar
39f54100a252f866e08bde3e8b4c3869e5b1604e
Cited by
60
References
45
Citations by year
2026: 1 · 2025: 4 · 2024: 5 · 2023: 3 · 2022: 3 · 2020: 8 · 2019: 4 · 2018: 4 · 2017: 7 · 2016: 3 · 2015: 5 · 2014: 5 · 2013: 6 · 2012: 2
FWCI
6.70
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • National Institutes of Health
  • National Institute of Neurological Disorders and Stroke (NS-11892, R01NS011892)
Topics
  • Health Sciences › Medicine › Reproductive Medicine › Endometriosis Research and Treatment
  • Health Sciences › Medicine › Physiology › Pain Mechanisms and Treatments
  • Health Sciences › Medicine › Anesthesiology and Pain Medicine › Pain Management and Treatment
Keywords
endometriosis, hyperalgesia, sensory nerve fibers, sympathetic innervation, neuropathic pain, inflammatory pain, vaginal pain, rat model
MeSH terms
Animals, Behavior, Animal, Cysts, Disease Models, Animal, Endometriosis, Evans Blue, Female, Hyperalgesia, Immunohistochemistry, Uterus, Vagina, Rats, Sprague-Dawley, Rats

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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