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Hathway GJ, Vega-Avelaira D, Fitzgerald M. A critical period in the supraspinal control of pain: opioid-dependent changes in brainstem rostroventral medulla function in preadolescence. Pain 2012; 153:775-783. [PMID: 22325744 PMCID: PMC3657184 DOI: 10.1016/j.pain.2011.11.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 10/19/2011] [Accepted: 11/07/2011] [Indexed: 01/14/2023]
Abstract
We have previously shown that the balance of electrically evoked descending brainstem control of spinal nociceptive reflexes undergoes a switch from excitation to inhibition in preadolescent rats. Here we show that the same developmental switch occurs when μ-opioid receptor agonists are microinjected into the rostroventral medulla (RVM). Microinjections of the μ-opioid receptor agonist [D-Ala(2), N-MePhe(4), Gly-ol]-enkephalin (DAMGO) into the RVM of lightly anaesthetised adult rats produced a dose-dependent decrease in mechanical nociceptive hindlimb reflex electromyographic activity. However, in preadolescent (postnatal day 21 [P21]) rats, the same doses of DAMGO produced reflex facilitation. RVM microinjection of δ-opioid receptor or GABA(A) receptor agonists, on the other hand, caused reflex depression at both ages. The μ-opioid receptor-mediated descending facilitation is tonically active in naive preadolescent rats, as microinjection of the μ-opioid receptor antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP) into the RVM at this age decreases spinal nociceptive reflexes while having no effect in adults. To test whether tonic opioid central activity is required for the preadolescent switch in RVM descending control, naloxone hydrochloride was delivered continuously from subcutaneous osmotic mini-pumps for 7-day periods, at various postnatal stages. Blockade of tonic opioidergic activity from P21 to P28, but not at earlier or later ages, prevented the normal development of descending RVM inhibitory control of spinal nociceptive reflexes. Enhancing opioidergic activity with chronic morphine over P7 to P14 accelerated this development. These results show that descending facilitation of spinal nociception in young animals is mediated by μ-opioid receptor pathways in the RVM. Furthermore, the developmental transition from RVM descending facilitation to inhibition of pain is determined by activity in central opioid networks at a critical period of periadolescence.
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Affiliation(s)
- Gareth J Hathway
- UCL Neuroscience, Physiology and Pharmacology, University College London, London, UK School of Biomedical Sciences, The University of Nottingham, Nottingham, UK
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102
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Chen Y, Li G, Huang LYM. P2X7 receptors in satellite glial cells mediate high functional expression of P2X3 receptors in immature dorsal root ganglion neurons. Mol Pain 2012; 8:9. [PMID: 22314033 PMCID: PMC3292910 DOI: 10.1186/1744-8069-8-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 02/07/2012] [Indexed: 11/27/2022] Open
Abstract
Background The purinergic P2X3 receptor (P2X3R) expressed in the dorsal root ganglion (DRG) sensory neuron and the P2X7 receptor (P2X7R) expressed in the surrounding satellite glial cell (SGC) are two major receptors participating in neuron-SGC communication in adult DRGs. Activation of P2X7Rs was found to tonically reduce the expression of P2X3Rs in DRGs, thus inhibiting the abnormal pain behaviors in adult rats. P2X receptors are also actively involved in sensory signaling in developing rodents. However, very little is known about the developmental change of P2X7Rs in DRGs and the interaction between P2X7Rs and P2X3Rs in those animals. We therefore examined the expression of P2X3Rs and P2X7Rs in postnatal rats and determined if P2X7R-P2X3R control exists in developing rats. Findings We immunostained DRGs of immature rats and found that P2X3Rs were expressed only in neurons and P2X7Rs were expressed only in SGCs. Western blot analyses indicated that P2X3R expression decreased while P2X7R expression increased with the age of rats. Electrophysiological studies showed that the number of DRG neurons responding to the stimulation of the P2XR agonist, α,β-meATP, was higher and the amplitudes of α,β-meATP-induced depolarizations were larger in immature DRG neurons. As a result, P2X3R-mediated flinching responses were much more pronounced in immature rats than those found in adult rats. When we reduced P2X7R expression with P2X7R-siRNA in postnatal and adult rats, P2X3R-mediated flinch responses were greatly enhanced in both rat populations. Conclusions These results show that the P2X7R expression increases as rats age. In addition, P2X7Rs in SGCs exert inhibitory control on the P2X3R expression and function in sensory neurons of immature rats, just as observed in adult rats. Regulation of P2X7R expression is likely an effective way to control P2X3R activity and manage pain relief in infants.
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Affiliation(s)
- Yong Chen
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1069, USA
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103
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Neonatal arthritis disturbs sleep and behaviour of adult rat offspring and their dams. Eur J Pain 2012; 14:985-91. [DOI: 10.1016/j.ejpain.2010.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 02/10/2010] [Accepted: 03/16/2010] [Indexed: 11/18/2022]
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104
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Wollgarten-Hadamekl I, Hohmeisterl J, Zohsell K, Florl H, Hermannl C. Do school-aged children with burn injuries during infancy show stress-induced activation of pain inhibitory mechanisms? Eur J Pain 2012; 15:423.e1-10. [DOI: 10.1016/j.ejpain.2010.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 07/30/2010] [Accepted: 09/05/2010] [Indexed: 10/19/2022]
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105
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Cignacco E, Hamers JPH, Stoffel L, van Lingen RA, Gessler P, McDougall J, Nelle M. The efficacy of non-pharmacological interventions in the management of procedural pain in preterm and term neonates. Eur J Pain 2012; 11:139-52. [PMID: 16580851 DOI: 10.1016/j.ejpain.2006.02.010] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 02/04/2006] [Accepted: 02/19/2006] [Indexed: 11/28/2022]
Abstract
BACKGROUND Neonates in a neonatal intensive care unit are exposed to a high number of painful procedures. Since repeated and sustained pain can have consequences for the neurological and behaviour-oriented development of the newborn, the greatest attention needs to be paid to systematic pain management in neonatology. Non-pharmacological treatment methods are being increasingly discussed with regard to pain prevention and relief either alone or in combination with pharmacological treatment. AIMS To identify effective non-pharmacological interventions with regard to procedural pain in neonates. METHODS A literature search was conducted via the MedLine, CINAHL, Cochrane Library databases and complemented by a handsearch. The literature search covered the period from 1984 to 2004. Data were extracted according to pre-defined criteria by two independent reviewers and methodological quality was assessed. RESULTS 13 randomised controlled studies and two meta-analyses were taken into consideration with regard to the question of current nursing practice of non-pharmacological pain management methods. The selected interventions were "non-nutritive sucking", "music", "swaddling", "positioning", "olfactory and multisensorial stimulation", "kangaroo care" and "maternal touch". There is evidence that the methods of "non-nutritive sucking", "swaddling" and "facilitated tucking" do have a pain-alleviating effect on neonates. CONCLUSIONS Some of the non-pharmacological interventions have an evident favourable effect on pulse rate, respiration and oxygen saturation, on the reduction of motor activity, and on the excitation states after invasive measures. However, unambiguous evidence of this still remains to be presented. Further research should emphasise the use of validated pain assessment instruments for the evaluation of the pain-alleviating effect of non-pharmacological interventions.
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Affiliation(s)
- Eva Cignacco
- Department for Obstetrics and Neonatology, Women's and Children's Clinic, University Hospital Insel, Bern, Effingerstr. 102, CH-3010 Bern, Switzerland.
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106
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Schmelzle-Lubiecki BM, Campbell KAA, Howard RH, Franck L, Fitzgerald M. Long-term consequences of early infant injury and trauma upon somatosensory processing. Eur J Pain 2012; 11:799-809. [PMID: 17320438 DOI: 10.1016/j.ejpain.2006.12.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2006] [Revised: 12/15/2006] [Accepted: 12/22/2006] [Indexed: 10/23/2022]
Abstract
Long-term consequences of early infant injury upon somatosensory processing were tested in school aged children. The aim was to test whether the long-term changes in sensitivity reported in animal models, in regions both local to and distant from the injury site, could be observed in humans. To do this we used quantitative sensory testing (QST) in children aged 9-12 years who had undergone cardiac surgery in infancy. Cutaneous mechanical and thermal thresholds were measured at the thoracic scar region and at control contralateral thoracic and reference thenar areas in this early surgery group (n=9), and compared with thresholds at the same regions in age and gender-matched controls (n=9). The results showed that the cardiac surgery group was significantly less sensitive to von Frey hair tactile stimulation in the non-injured thenar area than the control group; mean threshold 5.02, SD+/-1.59 compared to 2.76, SD+/-0.79 (von Frey hair number, p=0.04). In addition, their lateral thoracotomy scar areas were significantly less sensitive to von Frey hair stimulation (mean=9.82, SD+/-1.97, p<0.001) and to cooling and warming than any other site tested. Eight of the nine children in the early surgery group did not perceive warmth on their scars and were only able to detect uncomfortable heat as the temperature was raised. Three of these children felt a paradoxical cold prior to the hot sensation and all reported subtle abnormalities in everyday sensations. Questionnaires revealed perceived differences in pain perception, individual aberrant sensations and pain interfering with daily life that warrant further study. We conclude that tissue injured in early infancy remains measurably altered to mechanical and thermal stimulation in later life. These findings are consistent with the results of animal studies that early infant injury has not only local, but also global long-term consequences upon sensory processing.
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Affiliation(s)
- B M Schmelzle-Lubiecki
- UCL, Department of Anatomy and Developmental Biology, University College London, London, UK
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107
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Responses to pain in school-aged children with experience in a neonatal intensive care unit: Cognitive aspects and maternal influences. Eur J Pain 2012; 13:94-101. [DOI: 10.1016/j.ejpain.2008.03.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Revised: 02/19/2008] [Accepted: 03/01/2008] [Indexed: 11/18/2022]
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108
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Beggs S, Currie G, Salter MW, Fitzgerald M, Walker SM. Priming of adult pain responses by neonatal pain experience: maintenance by central neuroimmune activity. ACTA ACUST UNITED AC 2011; 135:404-17. [PMID: 22102650 DOI: 10.1093/brain/awr288] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Adult brain connectivity is shaped by the balance of sensory inputs in early life. In the case of pain pathways, it is less clear whether nociceptive inputs in infancy can have a lasting influence upon central pain processing and adult pain sensitivity. Here, we show that adult pain responses in the rat are 'primed' by tissue injury in the neonatal period. Rats that experience hind-paw incision injury at 3 days of age, display an increased magnitude and duration of hyperalgesia following incision in adulthood when compared with those with no early life pain experience. This priming of spinal reflex sensitivity was measured by both reductions in behavioural withdrawal thresholds and increased flexor muscle electromyographic responses to graded suprathreshold hind-paw stimuli in the 4 weeks following adult incision. Prior neonatal injury also 'primed' the spinal microglial response to adult injury, resulting in an increased intensity, spatial distribution and duration of ionized calcium-binding adaptor molecule-1-positive microglial reactivity in the dorsal horn. Intrathecal minocycline at the time of adult injury selectively prevented both the hyperalgesia and early microglial reactivity associated with prior neonatal injury. The enhanced neuroimmune response seen in neonatally primed animals could also be demonstrated in the absence of peripheral tissue injury by direct electrical stimulation of tibial nerve fibres, confirming that centrally mediated mechanisms contribute to these long-term effects. These data suggest that early life injury may predispose individuals to enhanced sensitivity to painful events.
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Affiliation(s)
- Simon Beggs
- Portex Unit: Pain Research, UCL Institute of Child Health and Great Ormond St Hospital NHS Trust, 30 Guilford St, London WC1N 1EH, UK
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109
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Early life adversity as a risk factor for fibromyalgia in later life. PAIN RESEARCH AND TREATMENT 2011; 2012:140832. [PMID: 22110940 PMCID: PMC3196867 DOI: 10.1155/2012/140832] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 07/25/2011] [Indexed: 12/03/2022]
Abstract
The impact of early life events is increasingly becoming apparent, as studies investigate how early childhood can shape long-term physiology and behaviour. Fibromyalgia (FM), which is characterised by increased pain sensitivity and a number of affective co-morbidities, has an unclear etiology. This paper discusses risk factors from early life that may increase the occurrence or severity of FM in later life: pain experience during neonatal life causes long-lasting changes in nociceptive circuitry and increases pain sensitivity in the older organism; premature birth and related stressor exposure cause lasting changes in stress responsivity; maternal deprivation affects anxiety-like behaviours that may be partially mediated by epigenetic modulation of the genome—all these adult phenotypes are strikingly similar to symptoms displayed by FM sufferers. In addition, childhood trauma and exposure to substances of abuse may cause lasting changes in developing neurotransmitter and endocrine circuits that are linked to anxiety and stress responses.
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110
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Page GG, Hayat MJ, Kozachik SL. Sex Differences in Pain Responses at Maturity Following Neonatal Repeated Minor Pain Exposure in Rats. Biol Res Nurs 2011; 15:96-104. [DOI: 10.1177/1099800411419493] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There is mounting evidence of long-lasting changes in pain sensitivity in school-age children who were cared for in a neonatal intensive care unit. Such care involves multiple pain exposures, 70% of which are accounted for by heel lance to monitor physiological well-being. The authors sought to model the repeated brief pain resulting from heel lance by administering repeated paw needle stick to neonatal rat pups. Repeated needle stick during the first 8 days of life was sex-specific in altering responses to mechanical and inflammatory stimuli, but not to a thermal stimulus, at maturity. Specifically, neonatal paw needle stick males exhibited significantly greater mechanical sensitivity in response to von Frey hair testing, whereas neonatal paw needle stick females exhibited significantly greater pain behavior scores following hindpaw formalin injection. This is the first study to show such sex-dependent changes in pain responsiveness at maturity in animals having experienced repeated neonatal needle stick pain. These findings support existing evidence that there are long-term sensory sequelae following neonatal pain experiences in rats and further suggest that there are sex-linked differences in the nature of the consequences. If these relationships hold in humans, these findings suggest that even mild painful insults early in life are not without sensory consequences.
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Affiliation(s)
- Gayle G. Page
- School of Nursing, Johns Hopkins University, Baltimore, MD, USA
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111
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Hains LE, Loram LC, Weiseler JL, Frank MG, Bloss EB, Sholar P, Taylor FR, Harrison JA, Martin TJ, Eisenach JC, Maier SF, Watkins LR. Pain intensity and duration can be enhanced by prior challenge: initial evidence suggestive of a role of microglial priming. THE JOURNAL OF PAIN 2011; 11:1004-14. [PMID: 20434956 DOI: 10.1016/j.jpain.2010.01.271] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Revised: 12/12/2009] [Accepted: 01/25/2010] [Indexed: 01/09/2023]
Abstract
UNLABELLED Activation of spinal microglia and consequent release of proinflammatory mediators facilitate pain. Under certain conditions, responses of activated microglia can become enhanced. Enhanced microglial production of proinflammatory products may result from priming (sensitization), similar to macrophage priming. We hypothesized that if spinal microglia were primed by an initial inflammatory challenge, subsequent challenges may create enhanced pain. Here, we used a "two-hit" paradigm using 2 successive challenges, which affect overlapping populations of spinal microglia, presented 2 weeks apart. Mechanical allodynia and/or activation of spinal glia were assessed. Initially, laparotomy preceded systemic lipopolysaccharide (LPS). Prior laparotomy caused prolonged microglial (not astrocyte) activation plus enhanced LPS-induced allodynia. In this "two-hit" paradigm, minocycline, a microglial activation inhibitor, significantly reduced later exaggerated pain induced by prior surgery when minocycline was administered intrathecally for 5 days starting either at the time of surgery or 5 days before LPS administration. To test generality of the priming effect, subcutaneous formalin preceded intrathecal HIV-1 gp120, which activates spinal microglia and causes robust allodynia. Prior formalin enhanced intrathecal gp120-induced allodynia, suggesting that microglial priming is not limited to laparotomy and again supporting a spinal site of action. Therefore, spinal microglial priming may increase vulnerability to pain enhancement. PERSPECTIVE Spinal microglia may become "primed" (sensitized) following their activation by disparate forms of peripheral trauma/inflammation. As a result, such primed microglia may overrespond to subsequent challenges, thereby enhancing pain intensity and duration.
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Affiliation(s)
- Leah E Hains
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado at Boulder, Boulder, Colorado 80309-0345, USA
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112
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Li J, Baccei ML. Neonatal tissue damage facilitates nociceptive synaptic input to the developing superficial dorsal horn via NGF-dependent mechanisms. Pain 2011; 152:1846-1855. [PMID: 21550171 DOI: 10.1016/j.pain.2011.04.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 03/17/2011] [Accepted: 04/01/2011] [Indexed: 11/29/2022]
Abstract
Tissue injury during a critical period of early life can facilitate spontaneous glutamatergic transmission within developing pain circuits in the superficial dorsal horn (SDH) of the spinal cord. However, the extent to which neonatal tissue damage strengthens nociceptive synaptic input to specific subpopulations of SDH neurons, as well as the mechanisms underlying this distinct form of synaptic plasticity, remains unclear. Here we use in vitro whole-cell patch clamp recordings from rodent spinal cord slices to demonstrate that neonatal surgical injury selectively potentiates high-threshold primary afferent input to immature lamina II neurons. In addition, the increase in the frequency of miniature excitatory postsynaptic currents after hindpaw incision was prevented by neonatal capsaicin treatment, suggesting that early tissue injury enhances glutamate release from nociceptive synapses. This occurs in a widespread manner within the developing SDH, as incision elevated miniature excitatory postsynaptic current frequency in both GABAergic and presumed glutamatergic lamina II neurons of Gad-GFP transgenic mice. The administration of exogenous nerve growth factor into the rat hindpaw mimicked the effects of early tissue damage on excitatory synaptic function, while blocking trkA receptors in vivo abolished the changes in both spontaneous and primary afferent-evoked glutamatergic transmission following incision. These findings illustrate that neonatal tissue damage can alter the gain of developing pain pathways by activating nerve growth factor-dependent signaling cascades, which modify synaptic efficacy at the first site of nociceptive processing within the central nervous system.
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Affiliation(s)
- Jie Li
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA
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113
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van Dijk M, Ceelie I, Tibboel D. Endpoints in pediatric pain studies. Eur J Clin Pharmacol 2011; 67 Suppl 1:61-6. [PMID: 21107829 PMCID: PMC3082693 DOI: 10.1007/s00228-010-0947-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 10/26/2010] [Indexed: 11/17/2022]
Abstract
Assessing pain intensity in (preverbal) children is more difficult than in adults. Tools to measure pain are being used as primary endpoints [e.g., pain intensity, time to first (rescue) analgesia, total analgesic consumption, adverse effects, and long-term effects] in studies on the effects of analgesic drugs. Here, we review current and promising new endpoints used in pediatric pain assessment studies.
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Affiliation(s)
- Monique van Dijk
- Intensive Care and Department of Pediatric Surgery, Erasmus MC–Sophia Children’s Hospital, P.O. Box 2040, 3000 CA Rotterdam, Netherlands
| | - Ilse Ceelie
- Intensive Care and Department of Pediatric Surgery, Erasmus MC–Sophia Children’s Hospital, P.O. Box 2040, 3000 CA Rotterdam, Netherlands
| | - Dick Tibboel
- Intensive Care and Department of Pediatric Surgery, Erasmus MC–Sophia Children’s Hospital, P.O. Box 2040, 3000 CA Rotterdam, Netherlands
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114
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Chang WK, Tao YX, Chuang CC, Chen PT, Chan KH, Chu YC. Lack of Beneficial Effect for Preemptive Analgesia in Postoperative Pain Control. Anesth Analg 2011; 112:710-8. [DOI: 10.1213/ane.0b013e318207c504] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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115
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The impact of the perioperative period on neurocognitive development, with a focus on pharmacological concerns. Best Pract Res Clin Anaesthesiol 2011; 24:433-49. [PMID: 21033018 DOI: 10.1016/j.bpa.2010.02.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Mounting evidence from animal studies has implicated that all commonly used anaesthetics and sedatives may induce widespread neuronal cell death and result in long-term neurological abnormalities. These findings have led to serious questions regarding the safe use of these drugs in young children. In humans, recent findings from retrospective, epidemiological studies do not exclude the possibility of an association between surgery with anaesthesia early in life and subsequent learning abnormalities. These results have sparked discussions regarding the appropriate timing of paediatric surgery and the safe management of paediatric anaesthesia. However, important questions need to be addressed before findings from laboratory studies and retrospective clinical surveys can be used to guide clinical practice. This article summarises the currently available preclinical and clinical information regarding the impact of anaesthetics, sedatives, opioids, pain and stress, inflammation, hypoxia-ischaemia, co-morbidities and genetic predisposition on brain structure and long-term neurological function. Moreover, this article outlines the putative mechanisms of anaesthetic neurotoxicity, and the phenomenon's implications for clinical practice in this rapidly emerging field.
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116
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Cortisol, behavior, and heart rate reactivity to immunization pain at 4 months corrected age in infants born very preterm. Clin J Pain 2011; 26:698-704. [PMID: 20664338 DOI: 10.1097/ajp.0b013e3181e5bb00] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Pain response may be altered in infants born very preterm owing to repeated exposure to procedures in the neonatal intensive care unit. Findings have been inconsistent in studies of behavioral and cardiac responses to brief pain in preterm versus full-term infants following neonatal intensive care unit discharge. To our knowledge, cortisol reactivity to pain has not been compared in preterm and full-term infants. We examined pain reactivity to immunization in preterm and full-term infants. METHOD Cortisol, facial behavior, and heart rate reactivity before, during, and after immunization were examined in infants born preterm at extremely low gestational age (ELGA 24 to 28 wk), very low gestational age (VLGA 29 to 32 wk), and full-term, at corrected age 4 months. RESULTS In all groups, cortisol, behavior, and heart rate increased during immunizations. Cortisol concentrations were lower in preterm ELGA and VLGA boys, compared with full-term boys. In contrast, facial and heart rate responses to immunization did not differ between preterm and full-term infants. DISCUSSION Although earlier reports found differences in pain processing in preterm infants earlier and later in development, the present findings indicate that pain responses, indexed by behavior and heart-rate, do not seem to differ in preterm compared with full-term infants at 4 months corrected age. Importantly, however, stress regulation seems altered in preterm male infants. As cortisol impacts development and functioning of the brain, altered stress regulation has important implications beyond pain systems.
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117
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Lin JYS, Cheng YC, Chen JYR, Chien CC, Lin SC, Wen YR, Tsou TS, Ling QD. Increased spinal prodynorphin gene expression in reinflammation-associated hyperalgesia after neonatal inflammatory insult. BMC Neurosci 2010; 11:139. [PMID: 20973986 PMCID: PMC2978219 DOI: 10.1186/1471-2202-11-139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Accepted: 10/25/2010] [Indexed: 01/24/2023] Open
Abstract
Background Neuroplasticity induced by neonatal inflammation is the consequence of a combination of activity-dependent changes in neurons. We investigated neuronal sensitivity to a noxious stimulus in a rat model of neonatal hind-paw peripheral inflammation and assessed changes in pain behaviour at the physiological and molecular levels after peripheral reinflammation in adulthood. Results A decrease in paw withdrawal latency (PWL) after a heat stimulus was documented in rats that received inflammatory injections in their left hind paws on postnatal day one (P1) and a reinflammation stimulus at postnatal 6-8 weeks of age, compared with normal rats. An increase in the expression of the prodynorphin (proDYN) gene was noted after reinflammation in the spinal cord ipsilateral to the afferents of the neonatally treated hind paw. The involvement of the activation of extracellular signal-regulated kinases (ERK) in peripheral inflammatory pain hypersensitivity was evidenced evident by the increase in phospho-ERK (pERK) activity after reinflammation. Conclusions Our results indicate that peripheral inflammation in neonates can permanently alter the pain processing pathway during the subsequent sensory stimulation of the region. Elucidation of the mechanism underlying the developing pain circuitry will provide new insights into the understanding of the early pain behaviours and the subsequent adaptation to pain.
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Affiliation(s)
- Jack Yu-Shih Lin
- Graduate Institute of Systems Biology and Bioinformatics, National Central University, Chungli, Taiwan
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118
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Interleukin-1 receptor antagonist ameliorates neonatal lipopolysaccharide-induced long-lasting hyperalgesia in the adult rats. Toxicology 2010; 279:123-9. [PMID: 20937348 DOI: 10.1016/j.tox.2010.10.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 10/02/2010] [Accepted: 10/04/2010] [Indexed: 11/23/2022]
Abstract
An increasing amount of data show that central inflammation contributes to many debilitating diseases and produces spontaneous pain and hyperalgesia (an increased sensitivity to painful stimuli), and these processes may be associated with the production of proinflammatory cytokines by activated microglia. In the present study, we demonstrate that neonatal intracerebral injection of lipopolysaccharide (LPS) (1mg/kg) in postnatal day 5 (P5) rats produced hyperalgesia that lasted into adulthood as indicated by decreased latency in the tail-flick test. Neonatal LPS administration resulted in a long-lasting increase in the number of activated microglial in the P70 rat brain. The effects of interleukin-1beta (IL-1β) and IL-1 receptor antagonists on hyperalgesia were determined to examine the possible role of inflammatory cytokines in LPS-induced hyperalgesia. Our data show that neonatal intracerebral injection of IL-1β (1 μg/kg) produced a hyperalgesic tendency similar to that induced by LPS. Neonatal administration of an IL-1 receptor antagonist (0.1mg/kg) significantly attenuated long-lasting hyperalgesia induced by LPS and reduced the number of activated microglia in the adult rat brain. These data reveal that neonatal intracerebral LPS exposure results in long-lasting hyperalgesia and an elevated number of activated microglia in later life. This effect is similar to that induced by IL-1β and can be prevented by an IL-1 receptor antagonist. The present study suggests that an IL-1 receptor antagonist effectively attenuates or blocks long-lasting hyperalgesia and microglia activation produced by LPS exposure in the neonatal period of rats.
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Bai G, Wei D, Zou S, Ren K, Dubner R. Inhibition of class II histone deacetylases in the spinal cord attenuates inflammatory hyperalgesia. Mol Pain 2010; 6:51. [PMID: 20822541 PMCID: PMC2942827 DOI: 10.1186/1744-8069-6-51] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 09/07/2010] [Indexed: 01/07/2023] Open
Abstract
Background Several classes of histone deacetylases (HDACs) are expressed in the spinal cord that is a critical structure of the nociceptive pathway. HDAC-regulated histone acetylation is an important component of chromatin remodeling leading to epigenetic regulation of gene transcription. To understand the role of histone acetylation in epigenetic regulation of pathological pain, we have studied the impact of different classes of HDACs in the spinal cord on inflammatory hyperalgesia induced by complete Freund's adjuvant (CFA). Results We intrathecally applied inhibitors specific to different classes of HDACs and evaluated their impact on inflammatory hyperalgesia. Pre-injected inhibitors targeting class I as well as II (SAHA, TSA, LAQ824) or IIa (VPA, 4-PB) HDACs significantly delayed the thermal hyperalgesia induced by unilateral CFA injection in the hindpaw. Existing hyperalgesia induced by CFA was also attenuated by the HDAC inhibitors (HDACIs). In contrast, these inhibitors did not interfere with the thermal response either in naïve animals, or on the contralateral side of inflamed animals. Interestingly, MS-275 that specifically inhibits class I HDACs failed to alter the hyperalgesia although it increased histone 3 acetylation in the spinal cord as SAHA did. Using immunoblot analysis, we further found that the levels of class IIa HDAC members (HDAC4, 5, 7, 9) in the spinal dorsal horn were upregulated following CFA injection while those of class I HDAC members (HDAC1, 2, 3) remained stable or were slightly reduced. Conclusions Our data suggest that activity of class II HDACs in the spinal cord is critical to the induction and maintenance of inflammatory hyperalgesia induced by CFA, while activity of class I HDACs may be unnecessary. Comparison of the effects of HDACIs specific to class II and IIa as well as the expression pattern of different HDACs in the spinal cord in response to CFA suggests that the members of class IIa HDACs may be potential targets for attenuating persistent inflammatory pain.
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Affiliation(s)
- Guang Bai
- Department of Neural and Pain Sciences, University of Maryland, Baltimore, Maryland 21117, USA.
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120
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Cerebral processing of pain in school-aged children with neonatal nociceptive input: An exploratory fMRI study. Pain 2010; 150:257-267. [DOI: 10.1016/j.pain.2010.04.004] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 02/16/2010] [Accepted: 04/06/2010] [Indexed: 12/22/2022]
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121
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Effects of neonatal inflammation on descending modulation from the rostroventromedial medulla. Brain Res Bull 2010; 83:16-22. [PMID: 20638459 DOI: 10.1016/j.brainresbull.2010.07.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 06/22/2010] [Accepted: 07/11/2010] [Indexed: 11/22/2022]
Abstract
Cutaneous tissue inflammation during the first postnatal week is known to alter long-term development of spinal cord nociceptive circuitry and to alter behavioral responses to noxious stimuli in adult animals. The impact of neonatal inflammation on descending projections arising from supraspinal sites that modulate spinal nociceptive processing is unknown. In the present study, we investigated if altered behavioral responses to pain in adult animals after neonatal inflammation are associated with changes in descending modulation of nocifensive responses elicited from the rostroventromedial medulla (RVM) in lightly anesthetized rats. Compared to handled control animals, hindpaw injection of 0.25% carrageenan (CG) at postnatal day 3 produced adult basal hypoalgesia and increased hyperalgesia 24 h after reinflammation with Complete Freund's Adjuvant (CFA) in awake animals. These effects were specific to the neonatally treated hindpaw, partially replicating previous findings, but were absent in lightly anesthetized animals. However, focal electrical stimulation of the RVM in lightly anesthetized CG treated animals produced significantly greater descending inhibition of nocifensive responses to noxious thermal stimuli applied to the hindpaws and the tail. These effects were partially replicated by intra-RVM microinjection of AMPA. No differences in the efficacy of RVM stimulation between CG and control animals were observed 24h after reinflammation with CFA. These findings indicate that neonatal tissue injury and inflammation produces lasting alterations in descending modulatory systems that modify nociceptive processing. Taken together with previous studies, these results indicate that changes in pain sensitivity following neonatal tissue injury involve long-term alterations in spinal and supraspinal circuitry.
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123
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Derbyshire SWG, Fitzgerald M. The painful consequences of neonatal nociceptive input. Pain 2010; 150:220-221. [PMID: 20494515 DOI: 10.1016/j.pain.2010.04.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Accepted: 04/30/2010] [Indexed: 10/19/2022]
Affiliation(s)
- Stuart W G Derbyshire
- School of Psychology, University of Birmingham, Edgbaston B15 2TT, UK Tel.: +44 121 414 4659. Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, UK
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124
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LaPrairie JL, Murphy AZ. Long-term impact of neonatal injury in male and female rats: Sex differences, mechanisms and clinical implications. Front Neuroendocrinol 2010; 31:193-202. [PMID: 20144647 PMCID: PMC2849925 DOI: 10.1016/j.yfrne.2010.02.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 02/01/2010] [Accepted: 02/03/2010] [Indexed: 02/07/2023]
Abstract
Over the last several decades, the relative contribution of early life events to individual disease susceptibility has been explored extensively. Only fairly recently, however, has it become evident that abnormal or excessive nociceptive activity experienced during the perinatal period may permanently alter the normal development of the CNS and influence future responses to somatosensory input. Given the significant rise in the number of premature infants receiving high-technology intensive care over the last 20 years, ex-preterm neonates may be exceedingly vulnerable to the long-term effects of repeated invasive interventions. The present review summarizes available clinical and laboratory findings on the lasting impact of exposure to noxious stimulation during early development, with a focus on the structural and functional alterations in nociceptive circuits, and its sexually dimorphic impact.
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Affiliation(s)
- Jamie L LaPrairie
- Neuroscience Institute, Georgia State University, 38 Peachtree Center Ave, 806 GCB, Atlanta, GA 30303, USA
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125
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Neonatal bladder inflammation produces functional changes and alters neuropeptide content in bladders of adult female rats. THE JOURNAL OF PAIN 2009; 11:247-55. [PMID: 19945355 DOI: 10.1016/j.jpain.2009.07.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 05/28/2009] [Accepted: 07/22/2009] [Indexed: 12/12/2022]
Abstract
UNLABELLED Neonatal bladder inflammation has been demonstrated to produce hypersensitivity to bladder re-inflammation as an adult. The purpose of this study was to investigate the effects of neonatal urinary bladder inflammation on adult bladder function and structure. Female Sprague-Dawley rats were treated on postnatal days 14 to 16 with intravesical zymosan or anesthesia alone. At 12 to 16 weeks of age, micturition frequency and cystometrograms were measured. Similarly treated rats had their bladders removed for measurement of plasma extravasation after intravesical mustard oil, for neuropeptide analysis (calcitonin gene-related peptide or Substance P) or for detailed histological examination. Rats treated with zymosan as neonates exhibited increased micturition frequency, reduced micturition volume thresholds, greater extravasation of Evans blue after intravesical mustard oil administration, and greater total bladder content of calcitonin gene-related peptide and Substance P. In contrast, there were no quantitative histological changes in the thickness, fibrosis, or mast cells of bladder tissue due to neonatal zymosan treatments. Functional changes in urologic systems observed in adulthood, coupled with the increased neuropeptide content and neurogenic plasma extravasation in adult bladders, suggest that the neonatal bladder inflammation treatment enhanced the number, function, and/or neurochemical content of primary afferent neurons. These data support the hypothesis that insults to the urologic system in infancy may contribute to the development of adult bladder hypersensitivity. PERSPECTIVE Inflammation of the bladder early in life in the rat has multiple sequelae, including laboratory measures that suggest an alteration of the neurophysiological substrates related to the bladder. Some painful bladder syndromes in humans have similar characteristics and so may be due to similar mechanisms.
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126
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Laprairie JL, Murphy AZ. Neonatal injury alters adult pain sensitivity by increasing opioid tone in the periaqueductal gray. Front Behav Neurosci 2009; 3:31. [PMID: 19862348 PMCID: PMC2766783 DOI: 10.3389/neuro.08.031.2009] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2009] [Accepted: 08/27/2009] [Indexed: 11/13/2022] Open
Abstract
Studies in both rodents and humans have shown that acute inflammatory pain experienced during the perinatal period produces long-term decreases in pain sensitivity (hypoalgesia) (Grunau et al., 1994a, 2001; Ren et al., 2004; LaPrairie and Murphy, 2007). To date, the mechanisms underlying these long-term adaptations, however, have yet to be elucidated. The present studies tested the hypothesis that neonatal inflammatory pain induces an upregulation in endogenous opioid tone that is maintained into adulthood, and that this increase in opioid tone provides the underlying mechanism for the observed hypoalgesia. On the day of birth (P0), inflammatory pain was induced in male and female Sprague-Dawley rats by intraplantar administration of carrageenan (CGN; 1%). In adulthood (P60), these animals displayed significantly increased paw withdrawal latencies in response to a noxious thermal stimulus in comparison to controls. Systemic administration of the brain-penetrant opioid receptor antagonist naloxone HCl, but not the peripherally restricted naloxone methiodide, significantly attenuated the injury-induced hypoalgesia. Direct administration of naloxone HCl or antagonists directed at the mu or delta opioid receptors into the midbrain periaqueductal gray (PAG) also significantly reversed the injury-induced hypoalgesia in adult rats. Parallel anatomical studies revealed that inflammatory pain experienced on the day of birth significantly increased beta-endorphin and met/leu-enkephalin protein levels and decreased opioid receptor expression in the PAG of the adult rat. Thus, early noxious insult produces long-lasting alterations in endogenous opioid tone, thereby profoundly impacting nociceptive responsiveness in adulthood.
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127
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Walker SM, Tochiki KK, Fitzgerald M. Hindpaw incision in early life increases the hyperalgesic response to repeat surgical injury: critical period and dependence on initial afferent activity. Pain 2009; 147:99-106. [PMID: 19781855 DOI: 10.1016/j.pain.2009.08.017] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2008] [Revised: 07/09/2009] [Accepted: 08/18/2009] [Indexed: 12/29/2022]
Abstract
Pain in early life can enhance the response to subsequent injury, but effects are influenced by both the nature and timing of neonatal injury. Using plantar hindpaw incision, we investigated how postnatal age influences the response to repeat surgical injury two weeks later. The degree and time course of behavioural changes in mechanical withdrawal threshold were measured, and injury-related hyperalgesia was further quantified by flexion reflex electromyographic responses to suprathreshold mechanical stimuli 24 h following incision. Plantar hindpaw incision produces acute mechanical hyperalgesia in neonatal and adult rats, but incision in neonatal pups has an additional effect on the response to subsequent injury. With initial incision at postnatal day (P) 3 or 6, the degree of hyperalgesia following repeat incision 2 weeks later was greater than in animals having a single incision at the same age. At older ages (initial incision at P10, P21 or P40) responses did not differ in repeat and single incision groups. To test the role of primary afferent activity, levobupivacaine sciatic block was performed prior to P6 plantar incision, and controls received saline or subcutaneous levobupivacaine. Repeat peri-operative, but not a single pre-operative sciatic block, prevented the enhanced response to repeat incision two weeks later. Our results show that the first postnatal week represents a critical period when incision increases hyperalgesia following repeat surgery two weeks later, and effects are initiated by peripheral afferent activity. This has potential therapeutic implications for the type and duration of peri-operative analgesia used for neonatal surgery.
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Affiliation(s)
- Suellen M Walker
- Portex Unit, Pain Research, UCL Institute of Child Health and Great Ormond St. Hospital, 6th Floor Cardiac Wing, London, UK.
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128
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Li J, Walker SM, Fitzgerald M, Baccei ML. Activity-dependent modulation of glutamatergic signaling in the developing rat dorsal horn by early tissue injury. J Neurophysiol 2009; 102:2208-19. [PMID: 19675290 DOI: 10.1152/jn.00520.2009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tissue injury in early life can produce distinctive effects on pain processing, but little is known about the underlying neural mechanisms. Neonatal inflammation modulates excitatory synapses in spinal nociceptive circuits, but it is unclear whether this results directly from altered afferent input. Here we investigate excitatory and inhibitory synaptic transmission in the rat superficial dorsal horn following neonatal hindlimb surgical incision using in vitro patch-clamp recordings and test the effect of blocking peripheral nerve activity on the injury-evoked changes. Surgical incision through the skin and muscle of the hindlimb at postnatal day 3 (P3) or P10 selectively increased the frequency, but not amplitude, of glutamatergic miniature excitatory postsynaptic currents (mEPSCs) recorded 2-3 days after injury, without altering miniature inhibitory postsynaptic current frequency or amplitude at this time point. Meanwhile, incision at P17 failed to affect excitatory or inhibitory synaptic function at 2-3 days postinjury. The elevated mEPSC frequency was accompanied by increased inward rectification of evoked alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated currents, but no change in AMPAR/N-methyl-D-aspartate receptor ratios, and was followed by a persistent reduction in mEPSC frequency by 9-10 days postinjury. Prolonged blockade of primary afferent input from the time of injury was achieved by administration of bupivacaine hydroxide or tetrodotoxin to the sciatic nerve at P3. The increase in mEPSC frequency evoked by P3 incision was prevented by blocking sciatic nerve activity. These results demonstrate that increased afferent input associated with peripheral tissue injury selectively modulates excitatory synaptic drive onto developing spinal sensory neurons and that the enhanced glutamatergic signaling in the dorsal horn following neonatal surgical incision is activity dependent.
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Affiliation(s)
- Jie Li
- Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio 45267, USA
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129
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Benatti C, Alboni S, Capone G, Corsini D, Caggia F, Brunello N, Tascedda F, Blom JMC. Early neonatal inflammation affects adult pain reactivity and anxiety related traits in mice: genetic background counts. Int J Dev Neurosci 2009; 27:661-8. [PMID: 19665540 DOI: 10.1016/j.ijdevneu.2009.07.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2009] [Revised: 07/03/2009] [Accepted: 07/30/2009] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED Protracted or recurrent pain and inflammation in the early neonatal period may cause long-lasting changes in central neural function. However, more research is necessary to better characterize the long-term behavioral sequelae of such exposure in the neonatal period. OBJECTIVES (1) to study whether timing of postnatal exposure to persistent inflammation alters responsiveness to thermal pain in the adult animal; (2) to assess whether animals experiencing early postnatal chronic inflammation display altered anxiety related behavior; (3) to study the importance of genetic background. Newborn mice (outbred strain, CD1 and F1 hybrid strain, B6C3F1) received an injection of Complete Freund's Adjuvant (CFA) or saline on either postnatal day 1 or 14 (PND1; PND14) into the left hind paw. Pain to radiant heat and anxiety were examined in 12-week-old adult animals. Adult baseline PWL was significantly decreased in CD1 mice exposed to CFA on PND 1 and 14 as compared to their saline treated counterparts. B6C3F1 mice exposed to CFA on PND14 showed markedly reduced baseline PWL compared to the PND14 saline group. Persistent inflammation experienced by B6C3F1 mice on PND1 failed to affect baseline adult thermal responsiveness. Adult mice, CD1 and B6C3F1, displayed low anxiety traits only if they had been exposed to persistent inflammation on PND1 and not on PND14. Our research suggests a role for genetic background in modulating long-term behavioral consequences of neonatal persistent inflammation: the data support the hypothesis that pain experienced very early in life differentially affects adult behavioral and emotional responsiveness in outbred (CD1) and hybrid mice (B6C3F1).
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Affiliation(s)
- Cristina Benatti
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, 41100 Modena, Italy
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130
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Laboureyras E, Chateauraynaud J, Richebé P, Simonnet G. Long-Term Pain Vulnerability After Surgery in Rats: Prevention by Nefopam, an Analgesic with Antihyperalgesic Properties. Anesth Analg 2009; 109:623-31. [DOI: 10.1213/ane.0b013e3181aa956b] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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131
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The effects of tail biopsy for genotyping on behavioral responses to nociceptive stimuli. PLoS One 2009; 4:e6457. [PMID: 19649248 PMCID: PMC2714470 DOI: 10.1371/journal.pone.0006457] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 07/01/2009] [Indexed: 11/18/2022] Open
Abstract
Removal of a small segment of tail at weaning is a common method used to obtain tissue for the isolation of genomic DNA to identify genetically modified mice. When genetically manipulated mice are used for pain research, this practice could result in confounding changes to the animals' responses to noxious stimuli. In this study, we sought to systematically investigate whether tail biopsy representative of that used in standard genotyping methods affects behavioral responses to a battery of tests of nociception. Wild-type littermate C57BL/6J and 129S6 female and male mice received either tail biopsies or control procedural handling at Day 21 after birth and were then tested at 6-9 weeks for mechanical and thermal sensitivity. C57BL/6J mice were also tested in the formalin model of inflammatory pain. In all tests performed (von Frey, Hargreaves, modified Randall Selitto, and formalin), C57BL/6J tail-biopsied animals' behavioral responses were not significantly different from control animals. In 129S6 animals, tail biopsy did not have a significant effect on behavioral responses in either sex to the von Frey and the modified Randall-Selitto tests of mechanical sensitivity. Interestingly, however, both sexes exhibited small but significant differences between tail biopsied and control responses to a radiant heat stimulus. These results indicate that tail biopsy for genotyping purposes has no effect on nocifensive behavioral responses of C57BL/6J mice, and in 129S6 mice, causes only a minor alteration in response to a radiant heat stimulus while other nocifensive behavioral responses are unchanged. The small effect seen is modality- and strain-specific.
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132
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Excitatory synapses in the rat superficial dorsal horn are strengthened following peripheral inflammation during early postnatal development. Pain 2009; 143:56-64. [DOI: 10.1016/j.pain.2009.01.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 12/30/2008] [Accepted: 01/22/2009] [Indexed: 11/19/2022]
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133
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Hathway GJ, Koch S, Low L, Fitzgerald M. The changing balance of brainstem-spinal cord modulation of pain processing over the first weeks of rat postnatal life. J Physiol 2009; 587:2927-35. [PMID: 19403624 DOI: 10.1113/jphysiol.2008.168013] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Brainstem-spinal cord connections play an essential role in adult pain processing, and the modulation of spinal pain network excitability by brainstem nuclei is known to contribute to hyperalgesia and chronic pain. Less well understood is the role of descending brainstem pathways in young animals when pain networks are more excitable and exposure to injury and stress can lead to permanent modulation of pain processing. Here we show that up to postnatal day 21 (P21) in the rat, the rostroventral medulla of the brainstem (RVM) exclusively facilitates spinal pain transmission but that after this age (P28 to adult), the influence of the RVM shifts to biphasic facilitation and inhibition. Graded electrical microstimulation of the RVM at different postnatal ages revealed a robust shift in the balance of descending control of both spinal nociceptive flexion reflex EMG activity and individual dorsal horn neuron firing properties, from excitation to inhibition, beginning after P21. The shift in polarity of descending control was also observed following excitotoxic lesions of the RVM in adult and P21 rats. In adults, RVM lesions decreased behavioural mechanical sensory reflex thresholds, whereas the same lesion in P21 rats increased thresholds. These data demonstrate, for the first time, the changing postnatal influence of the RVM in spinal nociception and highlight the central role of descending brainstem control in the maturation of pain processing.
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Affiliation(s)
- G J Hathway
- Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
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134
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Long‐lasting neonatal inflammation enhances pain responses to subsequent inflammation, but not peripheral nerve injury in adult rats. Int J Dev Neurosci 2009; 27:215-22. [PMID: 19429386 DOI: 10.1016/j.ijdevneu.2009.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 01/16/2009] [Accepted: 01/18/2009] [Indexed: 11/19/2022] Open
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135
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Wollgarten-Hadamek I, Hohmeister J, Demirakça S, Zohsel K, Flor H, Hermann C. Do burn injuries during infancy affect pain and sensory sensitivity in later childhood? Pain 2009; 141:165-72. [DOI: 10.1016/j.pain.2008.11.008] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 11/12/2008] [Accepted: 11/13/2008] [Indexed: 11/28/2022]
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136
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Fitzgerald M, Walker SM. Infant pain management: a developmental neurobiological approach. ACTA ACUST UNITED AC 2009; 5:35-50. [DOI: 10.1038/ncpneuro0984] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 10/31/2008] [Indexed: 12/21/2022]
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137
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Walker SM, Franck LS, Fitzgerald M, Myles J, Stocks J, Marlow N. Long-term impact of neonatal intensive care and surgery on somatosensory perception in children born extremely preterm. Pain 2009; 141:79-87. [PMID: 19026489 DOI: 10.1016/j.pain.2008.10.012] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 09/18/2008] [Accepted: 10/20/2008] [Indexed: 11/30/2022]
Affiliation(s)
- Suellen M Walker
- Portex Unit, Pain Research and Respiratory Physiology, UCL Institute of Child Health, 6th Floor Cardiac Wing, 30 Guilford St, London WC1N 1EH, UK.
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Comparison of the immediate effects of surgical incision on dorsal horn neuronal receptive field size and responses during postnatal development. Anesthesiology 2008; 109:698-706. [PMID: 18813050 DOI: 10.1097/aln.0b013e3181870a32] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Pain behavior in response to skin incision is developmentally regulated, but little is known about the underlying neuronal mechanisms. The authors hypothesize that the spatial activation and intensity of dorsal horn neuron responses to skin incision differ in immature and adult spinal cord. METHODS Single wide-dynamic-range dorsal horn cell spike activity was recorded for a minimum of 2 h from anesthetized rat pups aged 7 and 28 days. Cutaneous pinch and brush receptive fields were mapped and von Frey hair thresholds were determined on the plantar hind paw before and 1 h after a skin incision was made. RESULTS Baseline receptive field areas for brush and pinch were larger and von Frey thresholds lower in the younger animals. One hour after the incision, brush and pinch receptive field area, spontaneous firing, and evoked spike activity had significantly increased in the 7-day-old animals but not in the 28-day-old animals. Von Frey hair thresholds decreased at both ages. CONCLUSIONS Continuous recording from single dorsal horn cells both before and after injury shows that sensitization of receptive fields and of background and afferent-evoked spike activity at 1 h is greater in younger animals. This difference is not reflected in von Frey mechanical thresholds. These results highlight the importance of studying the effects of injury on sensory neuron physiology. Injury in young animals induces a marked and rapid increase in afferent-evoked activity in second-order sensory neurons, which may be important when considering long-term effects and analgesic interventions.
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139
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Kashaninia Z, Sajedi F, Rahgozar M, Noghabi FA. The effect of Kangaroo Care on behavioral responses to pain of an intramuscular injection in neonates. J SPEC PEDIATR NURS 2008; 13:275-80. [PMID: 19238715 DOI: 10.1111/j.1744-6155.2008.00165.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE This study aims to assess the efficacy of Kangaroo Care (KC) on behavioral responses of term neonates to the pain of an intramuscular injection. DESIGN AND METHODS One hundred healthy term neonates were enrolled and randomly assigned to intervention and control groups. In the intervention group, the neonate was held in KC for 10 min before the injection and remained in KC for the duration of the procedure. The primary outcome measure was the cumulative Neonatal Infant Pain Scale (NIPS) score immediately after injection. RESULTS The cumulative NIPS score immediately after injection in the intervention group was significantly lower (p<.001) than in the control group. PRACTICE IMPLICATIONS KC given before injection seems to effectively decrease pain and should be considered for minor invasive procedures in neonates.
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Affiliation(s)
- Zahra Kashaninia
- Nursing Department, University of Welfare & Rehabilitation, Tehran, Iran
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140
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Wang J, Gu C, Al-Chaer ED. Altered behavior and digestive outcomes in adult male rats primed with minimal colon pain as neonates. Behav Brain Funct 2008; 4:28. [PMID: 18616817 PMCID: PMC2518152 DOI: 10.1186/1744-9081-4-28] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 07/10/2008] [Indexed: 02/08/2023] Open
Abstract
Background Neonatal colon irritation (CI; pain or inflammation) given for 2 weeks prior to postnatal day 22 (PND22), causes long-lasting functional disorders in rats that can be seen 6 months after the initial insult. This study looked at the effect of varying the frequency and duration of neonatal CI on the rate of growth, digestive outcomes, exploratory activity, and colon and skin sensitivity in adult rats. Methods Male Sprague-Dawley rats were given CI using repeated colorectal distension (CRD) at different time intervals and for varying durations starting at PND 8, 10 or 14. Control rats were handled by the investigator without any intracolonic insertion. Further experiments were done on adult rats. Digestive outcomes (food and water consumption, fecal and urinary outputs) were measured using metabolic cages. Exploratory behavior was measured using digital video tracking in an open field. Cutaneous sensitivity was assessed by measuring the responses to mechanical and heat stimuli applied to the shaved abdomen or hind paws. Visceral sensitivity was measured by recording electromyographic responses, under light isoflurane anesthesia, from the external oblique muscles in response to CRD. Results No significant weight differences were observed between CI and control rats. Exploratory behavior was reduced in rats with neonatal CI compared to control. Digestive outputs and somatic and visceral sensitivity changed between different treatment groups with earlier and more frequent insults yielding a higher deviation from normal. Conclusion The diversity of behavioral and digestive symptoms in these rats parallels the diversity of symptoms in patients with functional gastrointestinal disorders and is consistent with global plastic changes affecting more than one system in the organism.
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Affiliation(s)
- Jing Wang
- Center for Pain Research, Departments of Pediatrics, Internal Medicine, Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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141
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Anseloni VCZ, Gold MS. Inflammation-induced shift in the valence of spinal GABA-A receptor-mediated modulation of nociception in the adult rat. THE JOURNAL OF PAIN 2008; 9:732-8. [PMID: 18467182 DOI: 10.1016/j.jpain.2008.03.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 03/11/2008] [Accepted: 03/12/2008] [Indexed: 11/18/2022]
Abstract
UNLABELLED The objective of this study was to assess the impact of persistent inflammation on spinal gamma-aminobutyric acid-A (GABA-A) receptor-mediated modulation of evoked nociceptive behavior in the adult rat. Nocifensive threshold was assessed with von Frey filaments applied to the dorsal surface of the hind paw. The GABA-A receptor agonist muscimol, the antagonist gabazine, the benzodiazepine receptor agonist midazolam, and antagonists PK11195 and flumazenil were administered spinally in the presence and absence of complete Freund's adjuvant (CFA)-induced inflammation. In naive rats, muscimol increased and gabazine decreased nociceptive threshold. After CFA, the effects of these compounds were reversed: Low doses of muscimol exacerbated the inflammation-induced decrease in nociceptive threshold and gabazine increased nociceptive threshold. Midazolam increased nociceptive threshold both in the presence and absence of inflammation. Flumazenil but not PK11195 blocked the analgesic effects of midazolam. These findings indicate that inflammation-induced changes in GABA-A signaling are complex and are likely to involve several distinct mechanisms. Rectifying the changes in GABA-A signaling may provide effective relief from hypersensitivity observed in the presence of inflammation. PERSPECTIVE An inflammation-induced shift in spinal GABA-A receptor signaling from inhibition to excitation appears to underlie inflammatory pain and hypersensitivity. Use of GABA-A receptor selective general anesthetics in association with therapeutic interventions may be contraindicated. More importantly, rectifying the changes in GABA-A signaling may provide effective relief from inflammatory hypersensitivity.
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Affiliation(s)
- Vanessa C Z Anseloni
- Department of Biomedical Sciences, School of Dentistry, Baltimore, Maryland, USA
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142
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Abstract
Significant advances in the assessment and management of acute pain in children have been made, and are supported by an increase in the availability and accessibility of evidence-based data. However, methodological and practical issues in the design and performance of clinical paediatric trials limit the quantity, and may influence the quality, of current data, which lags behind that available for adult practice. Collaborations within research networks, which incorporate both preclinical and clinical studies, may increase the feasibility and specificity of future trials. In early life, the developing nervous system responds differently to pain, analgesia, and injury, resulting in effects not seen in later life and which may have long-term consequences. Translational laboratory studies further our understanding of developmental changes in nociceptor pathway structure and function, analgesic pharmacodynamics, and the impact of different forms of injury. Chronic pain in children has a negative impact on quality of life, resulting in social and emotional consequences for both the child and the family. Despite age-related differences in many chronic pain conditions, such as neuropathic pain, management in children is often empirically based on data from studies in adults. There is a major need for further clinical research, training of health-care providers, and increased resources, to improve management and outcomes for children with chronic pain.
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Affiliation(s)
- S M Walker
- Portex Department of Anaesthesia, UCL Institute of Child Health and Great Ormond Street Hospital NHS Trust, 30 Guilford Street, London WC1N 1EH, UK.
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143
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Preterm births: can neonatal pain alter the development of endogenous gating systems? Eur J Pain 2008; 12:945-51. [PMID: 18308597 DOI: 10.1016/j.ejpain.2008.01.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 12/11/2007] [Accepted: 01/15/2008] [Indexed: 11/21/2022]
Abstract
Prematurity is known to affect the development of various neurophysiological systems, including the maturation of pain and cardiac circuits. The purpose of this study was to see if numerous painful interventions, experienced soon after birth, affect counterirritation-induced analgesia (triggered using the cold pressor test) later in life. A total of 26 children, between the ages of 7 and 11 participated in the study. Children were divided into three groups, according to their birth status (i.e., term-born, born preterm and exposed to numerous painful interventions, or born preterm and exposed to few painful interventions). Primary outcome measures were heat pain thresholds, heat sensitivity scores, and cardiac reactivity. Results showed that preterm children and term-born children had comparable pain thresholds. Exposure to conditioning cold stimulation significantly increased heart rate and significantly decreased the thermal pain sensitivity of term-born children. These physiological reactions were also observed among preterm children who were only exposed to a few painful interventions at birth. Changes in heart rate and pain sensitivity in response to conditioning cold stimulation were not observed in preterm children that had been exposed to numerous painful procedures during the neonatal period. These results suggest that early pain does not lead to enhanced pain sensitivity when premature babies become children, but that their endogenous pain modulatory mechanisms are not as well developed as those of children not exposed to noxious insult at birth. Greater frequency of painful procedures also dampened the rise in heart rate normally observed when experimental pain is experienced.
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144
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LaPrairie JL, Murphy AZ. Female rats are more vulnerable to the long-term consequences of neonatal inflammatory injury. Pain 2007; 132 Suppl 1:S124-S133. [PMID: 17904745 PMCID: PMC2121098 DOI: 10.1016/j.pain.2007.08.010] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 08/06/2007] [Accepted: 08/10/2007] [Indexed: 02/06/2023]
Abstract
Premature infants are routinely exposed to invasive medical procedures during neonatal intensive care treatment that are largely performed in the absence of anesthetics or analgesics. Data collected to date suggest that exposure to early insult during this time of increased plasticity alters the development of the CNS and influences future pain responses. As previous studies examining the impact of neonatal injury on nociception have been conducted primarily in males, the potential adverse effects on females are not known. Therefore, the present studies were conducted to determine whether neonatal injury differentially impacts male and female sensory thresholds in adulthood. A short lasting inflammatory response was evoked in male and female rats on the day of birth with an injection of carrageenan (CGN; 1% or 2%) into the right hindpaw. Nociceptive thresholds were assessed using a noxious thermal stimulus at both adolescence (P40) and adulthood (P60). A more persistent inflammation was subsequently evoked in adult rats with an intraplantar injection of Complete Freund's adjuvant (CFA). Neonatally injured females exhibited significantly greater hypoalgesia at P60, and displayed enhanced inflammatory hyperalgesia following re-injury in adulthood compared to neonatally injured males and controls. These results demonstrate that the long-term adverse effects of neonatal injury are exacerbated in females, and may contribute to the higher prevalence, severity and duration of pain syndromes noted in women compared to men.
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Affiliation(s)
- Jamie L LaPrairie
- Department of Biology, Center for Behavioral Neuroscience, Georgia State University, 24 Peachtree Center Ave, 402 Kell Hall, Atlanta, GA 30303-3088, USA
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145
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Yamamotová A, Franek M, Vaculín S, St'astný F, Bubeníková-Valesová V, Rokyta R. Different transfer of nociceptive sensitivity from rats with postnatal hippocampal lesions to control rats. Eur J Neurosci 2007; 26:446-50. [PMID: 17623020 DOI: 10.1111/j.1460-9568.2007.05666.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hippocampal lesions in newborn rats alter the development of mechanisms involved in the processing of nociception. The hippocampal lesion was induced by the bilateral infusion, into the lateral cerebral ventricles, of 0.25 microL of saline containing either 0.25 micromol quinolinic acid (QUIN) and/or 0.25 micromol N-acetyl-L-aspartyl-L-glutamate (NAAG) on postnatal day 12. The same amount of sterile saline was injected into the sham-operated animals (group SHAM). It was expected that the QUIN- and NAAG-lesioned rats would exhibit some differences in thermal pain perception; however, we wanted to know if the control rats would exhibit, at least in part, similar changes in pain perception as their chemically lesioned siblings with which they were housed. Young adult NAAG-injured rats exhibited increased withdrawal latencies in the tail-flick and plantar tests, whereas young adult QUIN-injured animals exhibited only marginally decreased latencies. Nociceptive responses in the SHAM rats paralleled the littermates that had been neonatally treated with QUIN or NAAG, i.e. the responses in the SHAM(QUIN) group decreased, whereas the responses in the SHAM(NAAG) group increased. No significant changes in nociception were observed in intact animals, regardless of which group they were housed with. Our results show that social factors, which were originally demonstrated only for the pain behavior, may also influence basal nociceptive sensitivity in rats. We concluded that the "sham operation" may have had a long-term, nonspecific impact on nociceptive behavior by inducing behavioral mimicry of other animals.
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Affiliation(s)
- Anna Yamamotová
- Department of Normal, Pathological and Clinical Physiology, Charles University, 3rd Faculty of Medicine, Ke Karlovu 4, 120 00 Prague 2, Czech Republic.
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146
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Lehr VT, Zeskind PS, Ofenstein JP, Cepeda E, Warrier I, Aranda JV. Neonatal Facial Coding System Scores and Spectral Characteristics of Infant Crying During Newborn Circumcision. Clin J Pain 2007; 23:417-24. [PMID: 17515740 DOI: 10.1097/ajp.0b013e31805476f2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To determine the relations between Neonatal Facial Coding System (NFCS) scores and measures of infant crying during newborn circumcision. METHODS Video and audio recordings were made of infant facial activity and cry sounds, respectively, during the lysis phase of circumcisions of 44 healthy term males (<3 d of age). All infants received topical analgesia before circumcision. NFCS scores were determined by blinded assistant from video recordings of facial activity. Measures of infant crying were determined via spectrum analysis of audio recordings by a blinded, independent researcher. Pearson product-moment correlations were used to examine relationship between NFCS scores and measures of crying. Principal component factor analysis detected dimensions underlying related measures of crying. Factor scores from a factor analysis were used in stepwise linear regression to predict NFCS scores. RESULTS Higher NFCS scores correlated with lower peak fundamental frequency of crying (P<0.01) and with higher amplitudes of crying at peak fundamental frequency and dominant frequency and in overall cry sample (P<0.01). The factor analysis showed 3 significant orthogonal dimensions underlying measures of crying: Power and Velocity (amplitude and rapidity), Pitch of Crying (frequency characteristics), and Infant Arousal (turbulence and intensity) accounting for 42.3%, 17.8%, and 14.6% of variance, respectively. A regression analysis showed all 3 factor scores accounted for significant and separate portions of variance (P<0.001). The best predictor of NFCS score was Power and Velocity (P<0.002), followed by Infant Arousal (P<0.002), and Pitch of Crying (P<0.007). DISCUSSION These data provide some of the first known evidence linking specific measures of infant crying with an independent, validated measure of pain.
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Affiliation(s)
- Victoria Tutag Lehr
- Division of Clinical Pharmacology and Toxicology, Children's Hospital of Michigan, 3901 Beaubien, Detroit, MI 48201, USA.
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147
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[Neurobiology of the chronicisation of pain in children: the memory of pain and its painful memory]. ACTA ACUST UNITED AC 2007; 26:540-5. [PMID: 17524600 DOI: 10.1016/j.annfar.2007.03.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reviewing the development of nociceptive circuits provides the rationale behind the need to modify and reduce premature painful experiences, especially during the "plastic" neonatal phase. Indeed, if physiological mechanisms of the functional nociceptive system follow a harmonious and predetermined development, it is the individual personal experience, intrinsically random, which will shape the final reactivity of this system and the later painful experience. If pain would not have been the organism's alarm system, we could have simply compared it by analogy to other sensorial systems, which its development depends exclusively on the presence of environmental stimuli. The eyes wait for light, the ears for sound, the skin to be touched, the tongue to taste and the olfactory bulbs to smell. However with pain it is not the quantitative exposure that determines its development, but rather the context-laden aspects of its affliction which in turn create the complex experience and "memory" of pain. Prolonged, but also "unnecessary" exposure to pain transforms it into a futile sensation, which impacts the individual immediately but also resonates into its future. This article reviews recent neurobiological mechanisms (such as neural circuitry, neurotrophins, peripheral and central sensitization, inhibitory pathways) now known to develop during the chronicisation and apprenticing of pain in the growing individual. Its cognizance is vital for a better comprehension of adult pain.
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148
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Moss A, Beggs S, Vega-Avelaira D, Costigan M, Hathway GJ, Salter MW, Fitzgerald M. Spinal microglia and neuropathic pain in young rats. Pain 2007; 128:215-224. [PMID: 17110040 DOI: 10.1016/j.pain.2006.09.018] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 08/23/2006] [Accepted: 09/11/2006] [Indexed: 01/18/2023]
Abstract
Neuropathic pain behaviour is not observed in neonatal rats and tactile allodynia does not develop in the spared nerve injury (SNI) model until rats are 4 weeks of age at the time of surgery. Since activated spinal microglia are known to play a key role in neuropathic pain, we have investigated whether the microglial response to nerve injury in young rats differs from that in adults. Here we show that dorsal horn microglial activation, visualised with IBA-1 immunostaining, is significantly less in postnatal day (P) 10 rat pups than in adults, 7 days after SNI. This was confirmed by qPCR analysis of IBA-1 mRNA and mRNA of other microglial markers, integrin-alpha M, MHC-II DMalpha and MHC-II DMbeta. Dorsal horn IBA-1+ve microglia could be activated, however, by intraspinal injections of lipopolysaccharide (LPS) or N-methyl-d-aspartate (NMDA) at P10, although the increase in the levels of mRNA for all microglial markers was less than in the adult rat. In addition, P10 rats developed a small but significant mechanical allodynia in response to intrathecal LPS. Intrathecal injection of cultured ATP-activated microglia, known to cause mechanical allodynia in adult rats, had no behavioural effect at P10 and only began to cause allodynia if injections were performed at P16. The results clearly demonstrate immaturity of the microglial response triggered by nerve injury in the first postnatal weeks which may explain the absence of tactile allodynia following peripheral nerve injury in young rats.
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Affiliation(s)
- Andrew Moss
- Department of Anatomy and Developmental Biology, University College London, London WC1E 6BT, UK The University of Toronto Centre for the Study of Pain, Toronto, Ontario, Canada Neural Plasticity Research Group, Department of Anesthesia and Critical Care, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
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149
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Pineles BL, Sandman CA, Waffarn F, Uy C, Davis EP. Sensitization of cardiac responses to pain in preterm infants. Neonatology 2007; 91:190-5. [PMID: 17377405 DOI: 10.1159/000097452] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 07/04/2006] [Indexed: 11/19/2022]
Abstract
BACKGROUND Preterm infants are repeatedly exposed to painful experiences as part of their care in the neonatal intensive care unit. There is evidence from both animal and human studies that exposure to pain during the neonatal period may have persisting consequences for development. OBJECTIVE To perform serial assessments of three heelstick blood draws to examine early changes both in physiological and behavioral responses to repeated exposure to painful stimuli in preterm infants. METHODS Heart rate and behavioral responses to three serially administered heelstick blood draws were evaluated in 22 medically stable preterm infants with less than 48 h of mechanical ventilation who were admitted to the neonatal intensive care unit. RESULTS Heart rate and behavioral agitation significantly increased during each heelstick as compared to baseline. The heart rate response was larger to the third heelstick as compared to the first two procedures. Behavioral responses did not change across the three assessments. CONCLUSIONS Healthy preterm infants sensitize to heelstick-induced pain, as measured by their heart rate responses. These data suggest that greater attention to the effects of repeated pain for the neonate is needed.
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Affiliation(s)
- Beth L Pineles
- Department of Psychiatry and Human Behavior, University of California, Irvine, California, USA
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150
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Hermann C, Hohmeister J, Demirakça S, Zohsel K, Flor H. Long-term alteration of pain sensitivity in school-aged children with early pain experiences. Pain 2006; 125:278-285. [PMID: 17011707 DOI: 10.1016/j.pain.2006.08.026] [Citation(s) in RCA: 286] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 07/17/2006] [Accepted: 08/21/2006] [Indexed: 11/21/2022]
Abstract
While animal studies suggest that neonatal pain experiences induce long-term alterations in pain sensitivity, no such data exist in humans. Changes in pain sensitivity in school-aged children (9-14 years) who were born preterm or fullterm, had been hospitalized for a prolonged period of time after birth and had undergone repeated painful procedures while being treated in a Neonatal Intensive Care Unit (NICU) were determined. A retrospective cohort study of 19 preterm (<or=31 weeks gestational age) and 20 fullterm children (>or=37 weeks gestational age) treated at least 3 days in a NICU at a University Hospital and 20 fullterm control children without NICU experience was performed. Perceptual sensitization to tonic heat and repetitive mechanical stimuli as well as heat pain and mechanical pain thresholds were obtained at the thenar and a trigeminal site. Length of hospitalization and NICU treatment was significantly higher in preterm than fullterm children. Nonetheless, both preterm and fullterm children with NICU experience showed greater perceptual sensitization to tonic heat and elevated heat pain thresholds at both sites. Mechanical pain threshold and perceptual sensitization did not differ between groups. Consistent with findings in animals, repeated pain experiences during the neonatal period were associated with alterations in thermal pain responsivity in school-aged preterm and fullterm children that was characterized by enhanced perceptual sensitization to prolonged painful stimulation and hypoalgesia to brief heat pain stimuli. Our findings suggest that repeated pain experiences in neonates may induce activity-induced changes in the functioning of pain pathways that persist well beyond infancy.
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Affiliation(s)
- Christiane Hermann
- Department of Clinical and Cognitive Neuroscience, University of Heidelberg, Central Institute of Mental Health, Mannheim, Germany Children's Hospital, Department of Clinical Medicine Mannheim, University of Heidelberg, Germany
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