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Barr GA, Opendak M, Perry RE, Sarro E, Sullivan RM. Infant pain vs. pain with parental suppression: Immediate and enduring impact on brain, pain and affect. PLoS One 2023; 18:e0290871. [PMID: 37972112 PMCID: PMC10653509 DOI: 10.1371/journal.pone.0290871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 08/18/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND In the short term, parental presence while a human infant is in pain buffers the immediate pain responses, although emerging evidence suggests repeated social buffering of pain may have untoward long-term effects. METHODS/FINDING To explore the short- and long-term impacts of social buffering of pain, we first measured the infant rat pup's [postnatal day (PN) 8, or 12] response to mild tail shock with the mother present compared to shock alone or no shock. Shock with the mother reduced pain-related behavioral activation and USVs of pups at both ages and reduced Fos expression in the periaqueductal gray, hypothalamic paraventricular nucleus, and the amygdala at PN12 only. At PN12, shock with the mother compared to shock alone differentially regulated expression of several hundred genes related to G-protein-coupled receptors (GPCRs) and neural development, whereas PN8 pups showed a less robust and less coherent expression pattern. In a second set of experiments, pups were exposed to daily repeated Shock-mother pairings (or controls) at PN5-9 or PN10-14 (during and after pain sensitive period, respectively) and long-term outcome assessed in adults. Shock+mother pairing at PN5-9 reduced adult carrageenan-induced thermal hyperalgesia and reduced Fos expression, but PN10-14 pairings had minimal impact. The effect of infant treatment on adult affective behavior showed a complex treatment by age dependent effect. Adult social behavior was decreased following Shock+mother pairings at both PN5-9 and PN10-14, whereas shock alone had no effect. Adult fear responses to a predator odor were decreased only by PN10-14 treatment and the infant Shock alone and Shock+mother did not differ. CONCLUSIONS/SIGNIFICANCE Overall, integrating these results into our understanding of long-term programming by repeated infant pain experiences, the data suggest that pain experienced within a social context impacts infant neurobehavioral responses and initiates an altered developmental trajectory of pain and affect processing that diverges from experiencing pain alone.
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Affiliation(s)
- Gordon A. Barr
- Department of Anesthesiology and Critical Care Medicine, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
- Perelman School of Medicine at the University of Pennsylvania, Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Maya Opendak
- Child Study Center, Center for Early Childhood Health & Development, Child & Adolescent Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, New York, United States of America
| | - Rosemarie E. Perry
- Child Study Center, Center for Early Childhood Health & Development, Child & Adolescent Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, New York, United States of America
| | - Emma Sarro
- Child Study Center, Center for Early Childhood Health & Development, Child & Adolescent Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, New York, United States of America
| | - Regina M. Sullivan
- Child Study Center, Center for Early Childhood Health & Development, Child & Adolescent Psychiatry, New York University School of Medicine, New York, New York, United States of America
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, New York, United States of America
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de Carvalho RC, Generoso LP, da Silva AL, Pereira GS, de Paula DC, Candido NL, Capello MGM, da Silva JRT, da Silva ML. Effects of repetitive pinprick stimulation on preterm offspring: Alterations in nociceptive responses and inflammatory hypersensitivity in adulthood. Behav Brain Res 2023; 454:114633. [PMID: 37597588 DOI: 10.1016/j.bbr.2023.114633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/14/2023] [Accepted: 08/14/2023] [Indexed: 08/21/2023]
Abstract
INTRODUCTION This study investigates the effects of repetitive pinprick stimulation on preterm offspring and its impact on nociceptive responses and inflammatory hypersensitivity in adulthood. OBJECTIVES The objective is to shed light on the potential long-term consequences of neonatal pain and prematurity on sensory processing. METHODS Term and preterm rats were subjected to repetitive pinprick (PP) stimulation or control (CC) during the neonatal period. Adult rats received CFA injection to induce inflammatory hypersensitivity, and mechanical hypersensitivity was measured. Gender differences in inflammatory hypersensitivity were also examined. Maternal behavior, litter weight, and offspring growth were monitored to assess any potential influences of the stimulation on these parameters. RESULTS In preterm rats, the PP stimulation did not affect baseline thresholds to mechanical stimuli, but increased mechanical hypersensitivity after CFA injection in adult rats. Females exhibited greater inflammatory hypersensitivity compared to males. Maternal behavior, litter weight, and offspring growth were not influenced by the stimulation. PP stimulation during the neonatal period led to changes in nociceptive responses in adulthood, potentially altering sensory processing. CONCLUSION PP stimulation in preterm rats during the neonatal period resulted in changes in nociceptive responses in adulthood, leading to increased inflammatory hypersensitivity. The study emphasizes how early development can significantly impact sensory processing and further highlights the potential long-term consequences of prematurity and neonatal pain on this processing.
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Affiliation(s)
- Ravena Carolina de Carvalho
- Postgraduate Program in Biosciences Applied to Health (PPGB), UNIFAL, Alfenas, MG, Brazil; Laboratory of Neuroscience, Neuromodulation and Study of Pain (LANNED), UNIFAL-MG, Alfenas, MG, Brazil
| | - Laura Pereira Generoso
- Postgraduate Program in Biosciences Applied to Health (PPGB), UNIFAL, Alfenas, MG, Brazil; Laboratory of Neuroscience, Neuromodulation and Study of Pain (LANNED), UNIFAL-MG, Alfenas, MG, Brazil
| | - Ana Laura da Silva
- Graduation in Physiotherapy at the Motricity Sciences Institute, UNIFAL, Alfenas, MG, Brazil; Laboratory of Neuroscience, Neuromodulation and Study of Pain (LANNED), UNIFAL-MG, Alfenas, MG, Brazil
| | - Gabrielly Santos Pereira
- Graduation in Physiotherapy at the Motricity Sciences Institute, UNIFAL, Alfenas, MG, Brazil; Laboratory of Neuroscience, Neuromodulation and Study of Pain (LANNED), UNIFAL-MG, Alfenas, MG, Brazil
| | - Danielle Cavalcante de Paula
- Graduation in Physiotherapy at the Motricity Sciences Institute, UNIFAL, Alfenas, MG, Brazil; Laboratory of Neuroscience, Neuromodulation and Study of Pain (LANNED), UNIFAL-MG, Alfenas, MG, Brazil
| | - Natalie Lange Candido
- Postgraduate Program in Biosciences Applied to Health (PPGB), UNIFAL, Alfenas, MG, Brazil; Laboratory of Neuroscience, Neuromodulation and Study of Pain (LANNED), UNIFAL-MG, Alfenas, MG, Brazil
| | - Maria Gabriela Maziero Capello
- Postgraduate Program in Biosciences Applied to Health (PPGB), UNIFAL, Alfenas, MG, Brazil; Laboratory of Neuroscience, Neuromodulation and Study of Pain (LANNED), UNIFAL-MG, Alfenas, MG, Brazil
| | | | - Marcelo Lourenço da Silva
- Laboratory of Neuroscience, Neuromodulation and Study of Pain (LANNED), UNIFAL-MG, Alfenas, MG, Brazil.
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Xu J, Wang Y, Zuo Y, Lv S, Li D. Repeated neonatal Needle-pricking stimulation alter neurodevelopment in adolescent rats. Brain Dev 2023; 45:413-421. [PMID: 37121792 DOI: 10.1016/j.braindev.2023.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/11/2023] [Accepted: 04/12/2023] [Indexed: 05/02/2023]
Abstract
OBJECTIVE To explore the repeated pain stimulation in neonatal rats affects their cognitive and memory abilities during puberty, and the proliferation expression of hippocampal neurons. METHODS Postnatal 1 day (P1) SD rats were randomly divided into two groups, and the skin of the needle group was pricked for seven days consecutively while the skin of the control group was stroked for the same period of time. The rats in both groups were weighed every week, and the Morris water maze experiment was performed from P44 to P49 to test the cognitive and memory abilities of the rats. On P50, the hippocampal tissue was extracted for observation of pathological features and the expressions of Ki-67 and caspase 3 were determined. RESULTS With the increase of the days, the body weight of the rats in the needle group increased slightly slower than that of the control group. The escape latency of the needle group was significantly higher than that of the control group in the water maze test at P45 and P48, and the number of times the rats crossing the platform in the needle group was lower than that of the control group. The HE staining of the hippocampal tissue showed that the cells in the needle group were disorganized, with irregular morphology. Under the electron microscope, the structure of neuron cells and organelles is changed in the hippocampal CA1 region of rats. It showed a decrease in the Ki-67 expression and an increase in caspase 3 in the needle group. CONCLUSION Repeated experience of needle-pricking stimulation in neonatal rats can cause cognitive impairment and memory loss in puberty, disrupt hippocampal organization, and diminish neuronal proliferation.
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Affiliation(s)
- Jing Xu
- Department of Neonatology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning Province, China
| | - Youhui Wang
- College of Basic Medical Sciences, Dalian Medical University, Dalian, Liaoning Province, China
| | - Yu Zuo
- Department of Neonatology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning Province, China
| | - Shuai Lv
- Department of Neonatology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning Province, China
| | - Dong Li
- Department of Neonatology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning Province, China; Department of Neonatology, Dalian Women and Children's Medical Group, Dalian, Liaoning Province, China.
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Zhang M, Alamaw E, Jampachaisri K, Huss M, Pacharinsak C. Effectiveness of two extended-release buprenorphine formulations during postoperative period in neonatal rats. PLoS One 2022; 17:e0276327. [PMID: 36251720 PMCID: PMC9576048 DOI: 10.1371/journal.pone.0276327] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 10/04/2022] [Indexed: 11/05/2022] Open
Abstract
Information on the effectiveness of a new long-lasting buprenorphine formulation, extended-release buprenorphine, in the neonatal rat is very limited. This study compares whether a high dose of extended-release buprenorphine (XR-Hi) attenuates thermal hypersensitivity for a longer period than a low dose of extended-release buprenorphine (XR-Lo) in a neonatal rat incisional pain model. Two experiments were performed. Experiment one: Male and female postnatal day-5 rat pups (n = 38) were randomly assigned to 1 of 4 treatment groups and received a subcutaneous administration of one of the following: 1) 0.9%NaCl (Saline), 0.1 mL; 2) sustained release buprenorphine (Bup-SR), 1 mg/kg; 3) XR-Lo, 0.65 mg/kg; and 4) XR-Hi, 1.3 mg/kg. Pups were anesthetized with sevoflurane in 100% O2 and a 5 mm long skin incision was made over the left lateral thigh and underlying muscle dissected. The skin was closed with surgical tissue glue. Thermal hypersensitivity testing (using a laser diode) and clinical observations were conducted 1 hour (h) prior to surgery and subsequently after 1, 4, 8, 24, 48, 72 h of treatment. Experiment two: The plasma buprenorphine concentration level was evaluated at 1, 4, 8, 24, 48, 72 h on five-day-old rat pups. Plasma buprenorphine concentration for all treatment groups remained above the clinically effective concentration of 1 ng/mL for at least 4 h in the Bup-SR group, 8 h in XR-Lo and 24 h in XR-Hi group with no abnormal clinical observations. This study demonstrates that XR-Hi did not attenuate postoperative thermal hypersensitivity for a longer period than XR-Lo in 5-day-old rats; XR-Hi attenuated postoperative thermal hypersensitivity for up to 4 h while Bup-SR and XR-Lo for at least 8 h in this model.
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Affiliation(s)
- Mingyun Zhang
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
| | - Eden Alamaw
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | | | - Monika Huss
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Cholawat Pacharinsak
- Department of Comparative Medicine, Stanford University School of Medicine, Stanford, California, United States of America
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Davis SM, Zuke JT, Berchulski MR, Burman MA. Amygdalar Corticotropin-Releasing Factor Signaling Is Required for Later-Life Behavioral Dysfunction Following Neonatal Pain. Front Physiol 2021; 12:660792. [PMID: 34045975 PMCID: PMC8144524 DOI: 10.3389/fphys.2021.660792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 03/31/2021] [Indexed: 11/13/2022] Open
Abstract
Neonatal pain such as that experienced by infants in the neonatal intensive care unit is known to produce later-life dysfunction including heightened pain sensitivity and anxiety, although the mechanisms remain unclear. Both chronic pain and stress in adult organisms are known to influence the corticotropin-releasing factor (CRF) system in the Central Nucleus of the Amygdala, making this system a likely candidate for changes following neonatal trauma. To examine this, neonatal rats were subjected to daily pain, non-painful handling or left undisturbed for the first week of life. Beginning on postnatal day, 24 male and female rats were subjected to a 4-day fear conditioning and sensory testing protocol. Some subjects received intra-amygdalar administration of either Vehicle, the CRF receptor 1 (CRF1) receptor antagonist Antalarmin, or the CRF receptor 2 (CRF2) receptor antagonist Astressin 2B prior to fear conditioning and somatosensory testing, while others had tissue collected following fear conditioning and CRF expression in the CeA and BLA was assessed using fluorescent in situ hybridization. CRF1 antagonism attenuated fear-induced hypersensitivity in neonatal pain and handled rats, while CRF2 antagonism produced a general antinociception. In addition, neonatal pain and handling produced a lateralized sex-dependent decrease in CRF expression, with males showing a diminished number of CRF-expressing cells in the right CeA and females showing a similar reduction in the number of CRF-expressing cells in the left BLA compared to undisturbed controls. These data show that the amygdalar CRF system is a likely target for alleviating dysfunction produced by early life trauma and that this system continues to play a major role in the lasting effects of such trauma into the juvenile stage of development.
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Affiliation(s)
- Seth M Davis
- Department of Psychology, University of New England, Biddeford, ME, United States.,Center for Excellence in the Neurosciences, University of New England, Biddeford, ME, United States
| | - Jared T Zuke
- Department of Psychology, University of New England, Biddeford, ME, United States.,Center for Excellence in the Neurosciences, University of New England, Biddeford, ME, United States
| | - Mariah R Berchulski
- Department of Psychology, University of New England, Biddeford, ME, United States.,Center for Excellence in the Neurosciences, University of New England, Biddeford, ME, United States
| | - Michael A Burman
- Department of Psychology, University of New England, Biddeford, ME, United States.,Center for Excellence in the Neurosciences, University of New England, Biddeford, ME, United States
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Nuseir KQ, Alzoubi KH, Alhusban AY, Alazzani M, Bawaane A, Khabour OF. Saccharin and naltrexone prevent increased pain sensitivity and impaired long-term memory induced by repetitive neonatal noxious stimulation: role of BDNF and enkephalin. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2021; 394:1641-1650. [PMID: 33829293 DOI: 10.1007/s00210-021-02086-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Accepted: 04/04/2021] [Indexed: 11/29/2022]
Abstract
This study aim to examine the hypothesis that repetitive painful stimuli during infancy will alter pain sensitivity and impair learning and memory during adulthood and that saccharin will prevent this through its analgesic effect. Naltrexone is used to examine if saccharin effect is mediated via the endogenous opioid system. Pain in rat pups was induced via needle pricks of the paws on day 1 of their birth (P0). All treatments/ manipulations started on day 1 and continued for 2 weeks. The radial arm water maze (RAWM) test was used to assess learning and memory. Pain threshold through foot-withdrawal response to a hot plate was also assessed. At the end of behavioral tests, animals were killed, hippocampus was dissected, and hippocampal levels of β-endorphin, enkephalin, and brain-derived neurotropic factor (BDNF) were assessed using ELISA. Naltrexone and saccharin combined normalized noxious stimulation induced increased pain sensitivity later in life. Furthermore, naltrexone and saccharin together mitigated the deficiency in learning and memory induced by noxious stimulation. Saccharin treatment prevented reduction in hippocampal enkephalin. Additionally, saccharin prevented hippocampal noxious stimulation induced BDNF decrement. Saccharin prevented long-term memory impairment during adulthood induced by repeated neonatal pain via mechanisms that appear to involve BDNF. Interestingly, naltrexone did not antagonize the effects of saccharin, instead naltrexone augmented saccharin effects.
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Affiliation(s)
- Khawla Q Nuseir
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, 22110, Jordan. .,School of Pharmacy and Pharmaceutical Sciences, University of California at Irvine, Irvine, CA, 92697, USA.
| | - Karem H Alzoubi
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Ahmed Y Alhusban
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Mohammed Alazzani
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Areej Bawaane
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Omar F Khabour
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan
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Juffinger A, Schoiswohl J, Stanitznig A, Krametter-Frötscher R, Wittek T, Waiblinger S. Mechanical Nociceptive Threshold, Tissue Alterations and Horn Growth in Calves after Injection of Isoeugenol or Clove Oil under the Horn Bud. Animals (Basel) 2021; 11:828. [PMID: 33804182 PMCID: PMC8000045 DOI: 10.3390/ani11030828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/04/2021] [Accepted: 03/10/2021] [Indexed: 11/16/2022] Open
Abstract
Disbudding of calves is a common, painful intervention. Due to cytotoxic and anesthetic properties, the injection of clove oil or its component isoeugenol may be less detrimental to animal welfare. We investigated mechanical nociceptive threshold (MNT), possible tissue alterations and horn growth for up to 12 weeks after injection of 1.5 mL clove oil (CLOV), isoeugenol (ISO) or saline (CON) or after hot-iron disbudding (BURN; with local anesthesia and sedation, n = 10/treatment). MNT was measured using von Frey filaments and a pressure algometer at four locations around the horn bud. There was a treatment*time point interaction (linear mixed model, p < 0.05). MNT decreased most strongly and for the longest time for BURN in most calves at least for 3 weeks. For ISO, the decrease was less distinct and most calves' values returned to baseline after 1-2 weeks. MNT in CLOV was intermediate, with decreased values up to 3 weeks in some animals. 12 weeks after the treatment, horn growth was prevented in about 50% of the horns in CLOV and ISO. Tissue alterations such as swellings of the eyelids often occurred in CLOV, but less so in ISO. Our results suggest that injection of isoeugenol causes less pain and thus seems to be beneficial compared to hot-iron disbudding, while clove oil was not advantageous. Regarding the effectiveness of isoeugenol to prevent horn growth, more studies are needed.
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Affiliation(s)
- Anna Juffinger
- Institute of Animal Welfare Science, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria;
| | - Julia Schoiswohl
- University Clinic for Ruminants, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria; (J.S.); (A.S.); (R.K.-F.); (T.W.)
| | - Anna Stanitznig
- University Clinic for Ruminants, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria; (J.S.); (A.S.); (R.K.-F.); (T.W.)
| | - Reinhild Krametter-Frötscher
- University Clinic for Ruminants, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria; (J.S.); (A.S.); (R.K.-F.); (T.W.)
| | - Thomas Wittek
- University Clinic for Ruminants, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria; (J.S.); (A.S.); (R.K.-F.); (T.W.)
| | - Susanne Waiblinger
- Institute of Animal Welfare Science, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Veterinärplatz 1, 1210 Vienna, Austria;
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Neonatal complete Freund's adjuvant-induced inflammation does not induce or alter hyperalgesic priming or alter adult distributions of C-fibre dorsal horn innervation. Pain Rep 2020; 5:e872. [PMID: 33274305 PMCID: PMC7704330 DOI: 10.1097/pr9.0000000000000872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 09/18/2020] [Accepted: 10/07/2020] [Indexed: 11/26/2022] Open
Abstract
Introduction: Inflammation during the neonatal period can exacerbate pain severity following reinjury in adulthood. This is driven by alterations in the postnatal development of spinal and supraspinal nociceptive circuitry. However, the contribution of alterations in peripheral nociceptor function remains underexplored. Objectives: We examined whether neonatal complete Freund's adjuvant (CFA)-induced inflammation induced or altered adult development of hyperalgesic priming (inflammation-induced plasticity in nonpeptidergic C fibres) or altered postnatal reorganization of calcitonin gene-related peptide (CGRP)-expressing and isolectin B4 (IB4)-binding C fibres in the spinal dorsal horn (DH). Methods: After intraplantar injection of CFA at postnatal day (P) 1, we assessed mechanical thresholds in adult (P60) rats before and after intraplantar carrageenan. One week later, intraplantar PGE2-induced hypersensitivity persisting for 4 hours was deemed indicative of hyperalgesic priming. CGRP expression and IB4 binding were examined in adult rat DH after CFA. Results: P1 CFA did not alter baseline adult mechanical thresholds, nor did it change the extent or duration of carrageenan-induced hypersensitivity. However, this was slower to resolve in female than in male rats. Rats that previously received carrageenan but not saline were primed, but P1 hind paw CFA did not induce or alter hyperalgesic priming responses to PGE2. In addition, CFA on P1 or P10 did not alter intensity or patterns of CGRP or IB4 staining in the adult DH. Conclusion: Complete Freund's adjuvant-induced inflammation during a critical period of vulnerability to injury during early postnatal development does not induce or exacerbate hyperalgesic priming or alter the broad distribution of CGRP-expressing or IB4-binding afferent terminals in the adult dorsal horn.
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Predisposition of Neonatal Maternal Separation to Visceral Hypersensitivity via Downregulation of Small-Conductance Calcium-Activated Potassium Channel Subtype 2 (SK2) in Mice. Neural Plast 2020; 2020:8876230. [PMID: 33029124 PMCID: PMC7528131 DOI: 10.1155/2020/8876230] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 08/31/2020] [Accepted: 09/06/2020] [Indexed: 12/13/2022] Open
Abstract
Background Visceral hypersensitivity is a common occurrence of gastrointestinal diseases such as irritable bowel syndrome (IBS), wherein early-life stress (ELS) may have a high predisposition to the development of visceral hypersensitivity in adulthood, with the specific underlying mechanism still elusive. Herein, we assessed the potential effect of small-conductance calcium-activated potassium channel subtype 2 (SK2) in the spinal dorsal horn (DH) on the pathogenesis of visceral hypersensitivity induced by maternal separation (MS) in mice. Methods Neonatal mice were subjected to the MS paradigm, an established ELS model. In adulthood, the visceral pain threshold and the abdominal withdrawal reflex (AWR) were measured with an inflatable balloon. The elevated plus maze, open field test, sucrose preference test, and forced swim test were employed to evaluate the anxiety- and depression-like behaviors. The expression levels of SK2 in the spinal DH were determined by immunofluorescence and western blotting. The mRNA of SK2 and membrane palmitoylated protein 2 (MPP2) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Electrophysiology was applied to evaluate the neuronal firing rates and SK2 channel-mediated afterhyperpolarization current (I AHP). The interaction between MPP2 and SK2 was validated by coimmunoprecipitation. Results In contrast to the naïve mice, ethological findings in MS mice revealed lowered visceral pain threshold, more evident anxiety- and depression-like behaviors, and downregulated expression of membrane SK2 protein and MPP2 protein. Moreover, electrophysiological results indicated increased neuronal firing rates and decreased I AHP in the spinal DH neurons. Nonetheless, intrathecal injection of the SK2 channel activator 1-ethyl-2-benzimidazolinone (1-EBIO) in MS mice could reverse the electrophysiological alterations and elevate the visceral pain threshold. In the naïve mice, administration of the SK2 channel blocker apamin abated I AHP and elevated spontaneous neuronal firing rates in the spinal DH neurons, reducing the visceral pain threshold. Finally, disruption of the MPP2 expression by small interfering RNA (siRNA) could amplify visceral hypersensitivity in naïve mice. Conclusions ELS-induced visceral pain and visceral hypersensitivity are associated with the underfunction of SK2 channels in the spinal DH.
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The Effects of Acute Neonatal Pain on Expression of Corticotropin-Releasing Hormone and Juvenile Anxiety in a Rodent Model. eNeuro 2019; 6:ENEURO.0162-19.2019. [PMID: 31601633 PMCID: PMC6860982 DOI: 10.1523/eneuro.0162-19.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 09/26/2019] [Accepted: 09/27/2019] [Indexed: 01/01/2023] Open
Abstract
Premature infants in the neonatal intensive care unit (NICU) may be subjected to numerous painful procedures without analgesics. One necessary, though acutely painful, procedure is the use of heel lances to monitor blood composition. The current study examined the acute effects of neonatal pain on maternal behavior as well as amygdalar and hypothalamic activation, and the long-term effects of neonatal pain on later-life anxiety-like behavior, using a rodent model. Neonatal manipulations consisted of either painful needle pricks or non-painful tactile stimulation in subjects’ left plantar paw surface which occurred four times daily during the first week of life [postnatal day (PND)1–PND7]. Additionally, maternal behaviors in manipulated litters were compared against undisturbed litters via scoring of videotaped interactions to examine the long-term effects of pain on dam-pup interactions. Select subjects underwent neonatal brain collection (PND6) and fluorescent in situ hybridization (FISH) for corticotropin-releasing hormone (CRH) and the immediate early gene c-fos. Other subjects were raised to juvenile age (PND24 and PND25) and underwent innate anxiety testing utilizing an elevated plus maze (EPM) protocol. FISH indicated that neonatal pain influenced amygdalar CRH and c-fos expression, predominately in males. No significant increase in c-fos or CRH expression was observed in the hypothalamus. Additionally, neonatal pain altered anxiety behaviors independent of sex, with neonatal pain subjects showing the highest frequency of exploratory behavior. Neonatal manipulations did not alter maternal behaviors. Overall, neonatal pain drives CRH expression and produces behavioral changes in anxiety that persist until the juvenile stage.
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