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Steinbauer P, Lisy T, Monje FJ, Chwala E, Wildner B, Schned H, Deindl P, Berger A, Giordano V, Olischar M. Impact of neonatal pain and opiate administration in animal models: A meta-analysis concerning pain threshold. Early Hum Dev 2024; 193:106014. [PMID: 38701669 DOI: 10.1016/j.earlhumdev.2024.106014] [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: 02/14/2024] [Revised: 04/16/2024] [Accepted: 04/17/2024] [Indexed: 05/05/2024]
Abstract
BACKGROUND AND AIM Neonatal intensive care treatment, including frequently performed painful procedures and administration of analgesic drugs, can have different effects on the neurodevelopment. This systematic review and meta-analysis aimed to investigate the influence of pain, opiate administration, and pre-emptive opiate administration on pain threshold in animal studies in rodents, which had a brain development corresponding to preterm and term infants. METHODS A systematic literature search of electronic data bases including CENTRAL (OVID), CINAHL (EBSCO), Embase.com, Medline (OVID), Web of Science, and PsycInfo (OVID) was conducted. A total of 42 studies examining the effect of pain (n = 38), opiate administration (n = 9), and opiate administration prior to a painful event (n = 5) in rodents were included in this analysis. RESULTS The results revealed that pain (g = 0.42, 95%CI 0.16-0.67, p = 0.001) increased pain threshold leading to hypoalgesia. Pre-emptive opiate administration had the opposite effect, lowering pain threshold, when compared to pain without prior treatment (g = -1.79, 95%CI -2.71-0.86, p = 0.0001). Differences were found in the meta regression for type of stimulus (thermal: g = 0.66, 95%CI 0.26-1.07, p = 0.001; vs. mechanical: g = 0.13, 95%CI -0.98-1.25, p = 0.81) and gestational age (b = -1.85, SE = 0.82, p = 0.027). In addition, meta regression indicated an association between higher pain thresholds and the amount of cumulative pain events (b = 0.06, SE = 0.03, p = 0.05) as well as severity of pain events (b = 0.94, SE = 0.28, p = 0.001). CONCLUSION Neonatal exposure to pain results in higher pain thresholds. However, caution is warranted in extrapolating these findings directly to premature infants. Further research is warranted to validate similar effects in clinical contexts and inform evidence-based practices in neonatal care.
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Affiliation(s)
- Philipp Steinbauer
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria.
| | - Tamara Lisy
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Francisco J Monje
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Eva Chwala
- Information Retrieval Office, University Library of the Medical University of Vienna, Vienna, Austria
| | - Brigitte Wildner
- Information Retrieval Office, University Library of the Medical University of Vienna, Vienna, Austria
| | - Hannah Schned
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Philipp Deindl
- Department of Neonatology and Pediatric Intensive Care Medicine, University Children's Hospital, University Medical Center Hamburg-Eppendorf, Germany
| | - Angelika Berger
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Vito Giordano
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Monika Olischar
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
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Dunn AD, Robinson SA, Nwokafor C, Estill M, Ferrante J, Shen L, Lemchi CO, Creus-Muncunill J, Ramirez A, Mengaziol J, Brynildsen JK, Leggas M, Horn J, Ehrlich ME, Blendy JA. Molecular and long-term behavioral consequences of neonatal opioid exposure and withdrawal in mice. Front Behav Neurosci 2023; 17:1202099. [PMID: 37424750 PMCID: PMC10324024 DOI: 10.3389/fnbeh.2023.1202099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 06/06/2023] [Indexed: 07/11/2023] Open
Abstract
Introduction Infants exposed to opioids in utero are at high risk of exhibiting Neonatal Opioid Withdrawal Syndrome (NOWS), a combination of somatic withdrawal symptoms including high pitched crying, sleeplessness, irritability, gastrointestinal distress, and in the worst cases, seizures. The heterogeneity of in utero opioid exposure, particularly exposure to polypharmacy, makes it difficult to investigate the underlying molecular mechanisms that could inform early diagnosis and treatment of NOWS, and challenging to investigate consequences later in life. Methods To address these issues, we developed a mouse model of NOWS that includes gestational and post-natal morphine exposure that encompasses the developmental equivalent of all three human trimesters and assessed both behavior and transcriptome alterations. Results Opioid exposure throughout all three human equivalent trimesters delayed developmental milestones and produced acute withdrawal phenotypes in mice reminiscent of those observed in infants. We also uncovered different patterns of gene expression depending on the duration and timing of opioid exposure (3-trimesters, in utero only, or the last trimester equivalent only). Opioid exposure and subsequent withdrawal affected social behavior and sleep in adulthood in a sex-dependent manner but did not affect adult behaviors related to anxiety, depression, or opioid response. Discussion Despite marked withdrawal and delays in development, long-term deficits in behaviors typically associated with substance use disorders were modest. Remarkably, transcriptomic analysis revealed an enrichment for genes with altered expression in published datasets for Autism Spectrum Disorders, which correlate well with the deficits in social affiliation seen in our model. The number of differentially expressed genes between the NOWS and saline groups varied markedly based on exposure protocol and sex, but common pathways included synapse development, the GABAergic and myelin systems, and mitochondrial function.
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Affiliation(s)
- Amelia D. Dunn
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Shivon A. Robinson
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
- Department of Psychology, Williams College, Williamstown, MA, United States
| | - Chiso Nwokafor
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Molly Estill
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Julia Ferrante
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Li Shen
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Crystal O. Lemchi
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Jordi Creus-Muncunill
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Angie Ramirez
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Juliet Mengaziol
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Julia K. Brynildsen
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States
| | - Mark Leggas
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Jamie Horn
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Michelle E. Ehrlich
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Julie A. Blendy
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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Taylor M, Cheng AB, Hodkinson DJ, Afacan O, Zurakowski D, Bajic D. Body size and brain volumetry in the rat following prolonged morphine administration in infancy and adulthood. FRONTIERS IN PAIN RESEARCH 2023; 4:962783. [PMID: 36923651 PMCID: PMC10008895 DOI: 10.3389/fpain.2023.962783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 01/20/2023] [Indexed: 02/28/2023] Open
Abstract
Background Prolonged morphine treatment in infancy is associated with a high incidence of opioid tolerance and dependence, but our knowledge of the long-term consequences of this treatment is sparse. Using a rodent model, we examined the (1) short- and (2) long-term effects of prolonged morphine administration in infancy on body weight and brain volume, and (3) we evaluated if subsequent dosing in adulthood poses an increased brain vulnerability. Methods Newborn rats received subcutaneous injections of either morphine or equal volume of saline twice daily for the first two weeks of life. In adulthood, animals received an additional two weeks of saline or morphine injections before undergoing structural brain MRI. After completion of treatment, structural T2-weigthed MRI images were acquired on a 7 T preclinical scanner (Bruker) using a RARE FSE sequence. Total and regional brain volumes were manually extracted from the MRI images using ITK-SNAP (v.3.6). Regions of interest included the brainstem, the cerebellum, as well as the forebrain and its components: the cerebral cortex, hippocampus, and deep gray matter (including basal ganglia, thalamus, hypothalamus, ventral tegmental area). Absolute (cm3) and normalized (as % total brain volume) values were compared using a one-way ANOVA with Tukey HSD post-hoc test. Results Prolonged morphine administration in infancy was associated with lower body weight and globally smaller brain volumes, which was not different between the sexes. In adulthood, females had lower body weights than males, but no difference was observed in brain volumes between treatment groups. Our results are suggestive of no long-term effect of prolonged morphine treatment in infancy with respect to body weight and brain size in either sex. Interestingly, prolonged morphine administration in adulthood was associated with smaller brain volumes that differed by sex only in case of previous exposure to morphine in infancy. Specifically, we report significantly smaller total brain volume of female rats on account of decreased volumes of forebrain and cortex. Conclusions Our study provides insight into the short- and long-term consequences of prolonged morphine administration in an infant rat model and suggests brain vulnerability to subsequent exposure in adulthood that might differ with sex.
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Affiliation(s)
- Milo Taylor
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA, United States
- Harvard College, Massachusetts Hall, Cambridge, MA, United States
| | - Anya Brooke Cheng
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA, United States
- Harvard College, Massachusetts Hall, Cambridge, MA, United States
| | - Duncan Jack Hodkinson
- Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham, United Kingdom
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, Nottingham, United Kingdom
- National Institute for Health Research (NIHR), Nottingham Biomedical Research Center, Queens Medical Center, Nottingham, United Kingdom
- Versus Arthritis Pain Centre, University of Nottingham, Nottingham, United Kingdom
| | - Onur Afacan
- Department of Radiology, Boston Children’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
| | - David Zurakowski
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
| | - Dusica Bajic
- Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, MA, United States
- Harvard Medical School, Boston, MA, United States
- Correspondence: Dusica Bajic
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Khani F, Pourmotabbed A, Hosseinmardi N, Nedaei SE, Fathollahi Y, Azizi H. Development of anxiety-like behaviors during adolescence: Persistent effects of adolescent morphine exposure in male rats. Dev Psychobiol 2022; 64:e22315. [PMID: 36282759 DOI: 10.1002/dev.22315] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 06/20/2022] [Accepted: 07/20/2022] [Indexed: 01/27/2023]
Abstract
Epidemiological studies show the prevalence of opioid use, misuse and abuse in adolescents, which imposes social and economic accountability worldwide. Chronic opioid exposure, especially in adolescents, may have lasting effects on emotional behaviors that persist into adulthood. The current experiments were therefore designed to study the effects of sustained opioid exposure during adolescence on anxiety-like behaviors. Adolescent male Wistar rats underwent increasing doses of morphine for 10 days (PNDs 31-40). After that the open field test (OFT) and elevated plus maze (EPM) test were performed over a 4-week postmorphine treatment from adolescence to adulthood. Moreover, the weight of the animals was measured at these time points. We found that chronic adolescent morphine exposure reduces the weight gain during the period of morphine treatment and 4 weeks after that. It had no significant effect on the locomotor activity in the animals. Moreover, anxiolytic-like behavior was observed in the rats exposed to morphine during adolescence evaluated by OFT and EPM test. Thus, long-term exposure to morphine during adolescence has the profound potential of altering the anxiety-like behavior profile in the period from adolescence to adulthood. The maturation of the nervous system can be affected by drug abuse during the developmental window of adolescence and these effects may lead to behaviorally stable alterations.
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Affiliation(s)
- Fatemeh Khani
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Ali Pourmotabbed
- Department of Physiology, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Narges Hosseinmardi
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed Ershad Nedaei
- Department of Physiology, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Yaghoub Fathollahi
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Hossein Azizi
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
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Lynch WJ, Bakhti-Suroosh A, Abel JM. Impact of high-access exercise prior to and during early adolescence on later vulnerability to opioid use and relapse in male rats. Transl Psychiatry 2022; 12:425. [PMID: 36192388 PMCID: PMC9529880 DOI: 10.1038/s41398-022-02180-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 09/07/2022] [Accepted: 09/13/2022] [Indexed: 11/15/2022] Open
Abstract
Middle- and high-school athletes participating in certain team sports are at greater risk of opioid misuse and addiction than those who do not. While this risk is thought to be due to increased access to opioids, in this study we explored the possibility that the sensitizing effects of discontinued high-intensity exercise may also contribute. Specifically, using male rat models with fentanyl, we tested the hypothesis that high-access exercise (24 h/day access to a running wheel) during pre/early adolescence (two weeks, postnatal-day 24-37) would enhance vulnerability to opioid use and relapse during late adolescence/adulthood. Rats with a history of high-access exercise showed stronger fentanyl-associated lever discrimination during acquisition, greater motivation to obtain infusions of fentanyl following acquisition, and had an enhanced sensitivity to the reinstating effects of fentanyl-associated cues following extended (24 h/day), intermittent-access self-administration and protracted abstinence (14 days) compared to sedentary controls. In contrast, sedentary rats had greater overall responding (active- and inactive-lever) during acquisition and greater non-specific (inactive-lever) responding during extended-access self-administration. Molecular markers associated with opioid seeking/relapse were also differentially expressed in the nucleus accumbens core of rats with versus without a history of high-access exercise following relapse testing (e.g., Bdnf-IV and Drd2 expression). Together, these findings demonstrate that high-access exercise prior to and throughout early-adolescence enhances vulnerability to the reinforcing and cue-induced reinstating effects of opioids during later adolescence/adulthood. Thus, it is possible that the discontinuation of high intensity exercise contributes to the enhanced vulnerability observed in middle- and high-school athletes.
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Affiliation(s)
- Wendy J Lynch
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, 22904, USA.
| | - Anousheh Bakhti-Suroosh
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, 22904, USA
| | - Jean M Abel
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA, 22904, USA
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Rêgo DDSB, Silva CS, Mello LEAM, Leslie ATFS. Early life nociceptive stimulus and fentanyl exposure increase hippocampal neurogenesis and anxiety but do not affect spatial learning and memory. Front Neurosci 2022; 16:988096. [PMID: 36248634 PMCID: PMC9557065 DOI: 10.3389/fnins.2022.988096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 09/07/2022] [Indexed: 11/15/2022] Open
Abstract
This study aimed to determine whether preemptive fentanyl administration in neonatal rats reduces the impact of a nociceptive stimulus initiated during the first day of life (P1) on hippocampal neurogenesis, behavior, and learning. At P1, Wistar rat pups received either a subcutaneous injection of fentanyl (F) before intraplantar injection of complete Freund’s adjuvant (CFA) (CFA + F group), an isolated injection of CFA (CFA group), or subcutaneous injection of fentanyl without CFA injection (F). Control animals received saline injections using the same route and volume as the treatment groups. Hippocampal neurogenesis was evaluated by 5′ –bromo-2′-deoxyuridine (BrdU) staining on P10 and P39 to assess neuronal proliferation and survival, respectively. Anxiety behavior in adulthood was assessed using an open field test (OF) and an elevated plus maze test (EPM). Spatial memory was assessed on a Morris water maze test (MWM), where the animals were trained for seven days, beginning on P81, and the probe trial was performed to evaluate memory retention. Although the CFA + F group showed an increased number of proliferative cells on P10, this finding did not persist on P39. The CFA + F group spent more time in the closed arms in the EPM, revealing more anxious behavior, although the early noxious experience, both with and without fentanyl, did not alter neurogenesis in adolescence and learning in adulthood. This study highlights that the impact of pain in early life pain combined with fentanyl on hippocampal neurogenesis on P10 did not persist on P39. In addition, this combined intervention during the first week of life was associated with higher anxiety levels.
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Affiliation(s)
| | - Clivandir S. Silva
- Laboratório de Neurobiologia, Departamento de Fisiologia, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Luiz Eugenio A. M. Mello
- Laboratório de Neurobiologia, Departamento de Fisiologia, Universidade Federal de São Paulo, São Paulo, Brazil
- Instituto D’Or de Pesquisa e Ensino, IDOr, São Paulo, Brazil
| | - Ana Teresa Figueiredo Stochero Leslie
- Laboratório de Neurobiologia, Departamento de Fisiologia, Universidade Federal de São Paulo, São Paulo, Brazil
- Departmento de Pediatria, Universidade Federal de São Paulo, São Paulo, Brazil
- *Correspondence: Ana Teresa Figueiredo Stochero Leslie,
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Neonatal Morphine Results in Long-Lasting Alterations to the Gut Microbiome in Adolescence and Adulthood in a Murine Model. Pharmaceutics 2022; 14:pharmaceutics14091879. [PMID: 36145627 PMCID: PMC9503694 DOI: 10.3390/pharmaceutics14091879] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/01/2022] [Accepted: 09/03/2022] [Indexed: 11/16/2022] Open
Abstract
Despite the many advancements in the field of pain management, the use of intravenous opioids, such as morphine, in neonates is still a challenge for clinicians and researchers, as the available evidence concerning the long-term consequences of such an early exposure is limited. In particular, little is known concerning the long-term consequences of neonatal morphine exposure on the gut microbiome, which has been identified as a key modulator of health and diseases. Consequently, the purpose of this study was to investigate those long-term consequences of neonatal morphine on the gut microbiome. Newborn mice were exposed to either morphine (5 mg/kg/day) or saline for a duration of 7 ± 2 days. Fecal samples were collected during adolescence and adulthood to longitudinally assess the gut microbiome. DNA extracted from the stool samples were sent out for 16s rRNA sequencing. During adolescence, neonatal morphine resulted in a significant increase of α-diversity and an overall decrease in the abundance of several commensal genera. During adulthood, β-diversity revealed a significantly different microbial composition of the neonatally morphine-exposed mice than that of the controls. The results demonstrate that morphine exposure during this critical developmental period resulted in long-lasting changes, particularly a reduction in several commensal bacteria. Thus, an adjunct therapeutic intervention with probiotics could potentially be used along with opioids to manage pain while attenuating the long-term co-morbidities of neonatal morphine later in life.
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Steinbauer P, Monje FJ, Kothgassner O, Goreis A, Eva C, Wildner B, Schned H, Deindl P, Seki D, Berger A, Olischar M, Giordano V. The consequences of neonatal pain, stress and opiate administration in animal models: An extensive meta-analysis concerning neuronal cell death, motor and behavioral outcomes. Neurosci Biobehav Rev 2022; 137:104661. [PMID: 35427643 DOI: 10.1016/j.neubiorev.2022.104661] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 01/21/2023]
Abstract
This systematic review and meta-analysis aimed to investigate the association of neonatal exposure to pain, stress, opiate administration alone, as well as opiate administration prior to a painful procedure on neuronal cell death, motor, and behavioral outcomes in rodents. In total, 36 studies investigating the effect of pain (n = 18), stress (n = 15), opiate administration (n = 13), as well as opiate administration prior to a painful event (n = 7) in rodents were included in our meta-analysis. The results showed a large effect of pain (g = 1.37, 95% CI 1.00-1.74, p < .001) on neuronal cell death. Moreover, higher number of neonatal pain events were significantly associated with increased neuronal cell death, increased anxiety (b = -1.18, SE = 0.43, p = .006), and depressant-like behavior (b = 1.74, SE = 0.51, p = .027) in rodents. Both opiates and pain had no impact on motor function (g = 0.26, 95% CI 0.18-0.70, p = .248).
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Affiliation(s)
- Philipp Steinbauer
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria.
| | - Francisco J Monje
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Oswald Kothgassner
- Department of Child and Adolescent Psychiatry, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Andreas Goreis
- Department of Clinical and Health Psychology, Faculty of Psychology, University of Vienna, Vienna, Austria; Outpatient Unit for Research, Teaching and Practice, Faculty of Psychology, University of Vienna, Vienna, Austria
| | - Chwala Eva
- Information Retrieval Office, University Library of the Medical University of Vienna, Vienna, Austria
| | - Brigitte Wildner
- Information Retrieval Office, University Library of the Medical University of Vienna, Vienna, Austria
| | - Hannah Schned
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Philipp Deindl
- Department of Neonatology and Pediatric Intensive Care Medicine, University Children's Hospital, University Medical Center Hamburg, Eppendorf, Germany
| | - David Seki
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria; Department of Microbiology and Ecosystem Science Division of Microbial Ecology, Vienna, Austria
| | - Angelika Berger
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Monika Olischar
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Vito Giordano
- Division of Neonatology, Pediatric Intensive Care and Neuropediatrics, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
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Yazdanfar N, Ali Mard S, Mahmoudi J, Bakhtiari N, Sarkaki A, Farnam A. Maternal Morphine Exposure and Post-Weaning Social Isolation Impair Memory and Ventral Striatum Dopamine System in Male Offspring: Is an Enriched Environment Beneficial? Neuroscience 2021; 461:80-90. [PMID: 33662528 DOI: 10.1016/j.neuroscience.2021.02.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 12/19/2022]
Abstract
Maternal opioids abuse has some deleterious consequences on next generations. Besides, children's rearing conditions can affect the behavioral states and brain plasticity in their later life. In the present study, we investigated the effects of maternal morphine (MOR) treatment and post-weaning rearing conditions on memory, pain threshold, and the ventral striatum dopaminergic activity in male offspring. Female Wistar rats were treated twice daily either with escalating doses of MOR or with normal saline (NS) one week before mating, during pregnancy and lactation. After weaning, the male pups were assigned to six groups and then raised for an 8-week period under three different conditions: standard (STD), isolated (ISO) or enriched environment (EE). The behavioral tests, including passive avoidance task, novel object recognition, and tail-flick test, were also performed. Moreover, the ventral striatum dopamine's content (DA), mRNA expressions of dopamine receptor 1(D1R) and dopamine receptor 2 (D2R), and dopamine transporter (DAT) were evaluated. The obtained data showed that maternal MOR exposure and post-weaning social isolation could dramatically impair memory in offspring, while EE could reverse these adverse outcomes. Moreover, results of tail flick latency indicated the increased pain threshold in EE animals. At molecular level, maternal MOR injections and social isolation reduced DA levels and altered expressions of D1R, D2R, and DAT within the ventral striatum of these male offspring. However, post-weaning EE partially buffered these changes. Our finding signified the effects of maternal MOR exposure and social isolation on the behaviors and neurochemistry of brain in next generation, and it also provided evidence on reversibility of these alterations following EE.
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Affiliation(s)
- Neda Yazdanfar
- Department of Neuroscience and Cognition, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran; Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Seyed Ali Mard
- The Persian Gulf Physiology Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; Department of Physiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Javad Mahmoudi
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Nima Bakhtiari
- Pain Research Center, Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Alireza Sarkaki
- The Persian Gulf Physiology Research Center, Medical Basic Sciences Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran; Department of Physiology, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
| | - Alireza Farnam
- Research Center of Psychiatry and Behavioral Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
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Identifying the Neurodevelopmental Differences of Opioid Withdrawal. Cell Mol Neurobiol 2021; 41:1145-1155. [PMID: 33432504 DOI: 10.1007/s10571-020-01035-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 12/28/2020] [Indexed: 01/01/2023]
Abstract
Stopping opioid medications can result in a debilitating withdrawal syndrome in chronic users. Opioid withdrawal can occur at all ages, but mechanistic understanding of this condition is predominantly derived from adult studies. Here, we examined whether there are age-dependent differences in the behavioural phenotype and cellular indices of opioid withdrawal. We tested this by assessing the behavioural and cFos response (a surrogate marker for neuronal activation) to morphine withdrawal in C57BL/6J mice across key developmental stages-neonatal, adolescent, and adulthood. Mice in all age groups received escalating doses of morphine (10-50 mg/kg) over 5 days and withdrawal was precipitated by a single injection of the opioid receptor antagonist naloxone (2 mg/kg) two hours after the last morphine dose. In adult and adolescent mice, withdrawal behaviours were robust, with age-related differences in autonomic and somatic signs. In both groups, cFos expression was increased in spinally projecting neurons within the Periaqueductal Grey (PAG), Rostro-ventromedial Medulla (RVM), and Locus Coeruleus. Neonatal animals displayed both a distinct behavioural withdrawal and cFos expression profile. Notably, in young animals cFos expression was increased within the PAG and LC, but decreased in the RVM. In summary, naloxone challenge precipitated robust opioid withdrawal behaviours across all developmental stages with neonatal animals displaying differences in withdrawal behaviours and unique neuronal activation patterns within key brainstem regions.
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11
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Robinson SA, Jones AD, Brynildsen JK, Ehrlich ME, Blendy JA. Neurobehavioral effects of neonatal opioid exposure in mice: Influence of the OPRM1 SNP. Addict Biol 2020; 25:e12806. [PMID: 31267641 PMCID: PMC8450766 DOI: 10.1111/adb.12806] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 01/09/2023]
Abstract
Opioid use among pregnant women is a growing public health concern in the United States. Infants exposed to opioids in utero are at risk of exhibiting neonatal opioid withdrawal syndrome (NOWS). The biological mechanisms underlying short and long-term consequences of in utero opioid exposure and NOWS are unknown. A potential genetic factor is a single-nucleotide polymorphism (SNP) in the mu-opioid receptor gene (OPRM1 A118G). Opioid exposed infants with the G-allele spend less time in hospitals after birth. To determine whether this SNP modulates the neurobehavioral effects of neonatal opioid exposure and withdrawal, we used mice possessing the equivalent Oprm1 SNP (A112G). Pups were treated chronically with saline or morphine from postnatal days (PNDs) 1 to 14, a developmental period equivalent to the third trimester of a human pregnancy and a sensitive period for opioid exposure in rodents. Morphine treatment produced significant developmental delays regardless of genotype and increased total ultrasonic vocalizations in males during spontaneous withdrawal. Animals were aged and tested for anxiety and drug response during adolescence and adulthood, respectively. AA morphine-treated animals showed reduced activity in the marble burying task compared with saline controls; however, this effect was absent in AG and GG animals. As adults, AA males exposed to morphine from PNDs 1 to 14 exhibited enhanced development of locomotor sensitization to morphine, whereas females showed reduced locomotor sensitization. These data suggest the involvement of the Oprm1 SNP for certain outcomes of neonatal opioid exposure and highlight the importance of considering sex and genetic variability for the prognosis of NOWS.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Behavior, Animal/drug effects
- Brain/drug effects
- Disease Models, Animal
- Female
- Male
- Mice
- Mice, Inbred C57BL
- Opioid-Related Disorders/genetics
- Polymorphism, Single Nucleotide/drug effects
- Polymorphism, Single Nucleotide/genetics
- Pregnancy
- Prenatal Exposure Delayed Effects/genetics
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/genetics
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Affiliation(s)
- Shivon A. Robinson
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia PA, 19104
| | - Alonzo D. Jones
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia PA, 19104
| | - Julia K. Brynildsen
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia PA, 19104
| | - Michelle E. Ehrlich
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York NY, 10029
| | - Julie A. Blendy
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia PA, 19104
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12
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Potential Neurodevelopmental Effects of Pediatric Intensive Care Sedation and Analgesia: Repetitive Benzodiazepine and Opioid Exposure Alters Expression of Glial and Synaptic Proteins in Juvenile Rats. Crit Care Explor 2020; 2:e0105. [PMID: 32426747 PMCID: PMC7188419 DOI: 10.1097/cce.0000000000000105] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Sedatives are suspected contributors to neurologic dysfunction in PICU patients, to whom they are administered during sensitive neurodevelopment. Relevant preclinical modeling has largely used comparatively brief anesthesia in infant age-approximate animals, with insufficient study of repetitive combined drug administration during childhood. We hypothesized that childhood neurodevelopment is selectively vulnerable to repeated treatment with benzodiazepine and opioid. We report a preclinical model of combined midazolam and morphine in early childhood age-approximate rats.
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13
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Carlson SW, Saatman KE. Central Infusion of Insulin-Like Growth Factor-1 Increases Hippocampal Neurogenesis and Improves Neurobehavioral Function after Traumatic Brain Injury. J Neurotrauma 2018; 35:1467-1480. [PMID: 29455576 PMCID: PMC5998830 DOI: 10.1089/neu.2017.5374] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Traumatic brain injury (TBI) produces neuronal dysfunction and cellular loss that can culminate in lasting impairments in cognitive and motor abilities. Therapeutic agents that promote repair and replenish neurons post-TBI hold promise in improving recovery of function. Insulin-like growth factor-1 (IGF-1) is a neurotrophic factor capable of mediating neuroprotective and neuroplasticity mechanisms. Targeted overexpression of IGF-1 enhances the generation of hippocampal newborn neurons in brain-injured mice; however, the translational neurogenic potential of exogenously administered IGF-1 post-TBI remains unknown. In a mouse model of controlled cortical impact, continuous intracerebroventricular infusion of recombinant human IGF-1 (hIGF) for 7 days, beginning 15 min post-injury, resulted in a dose-dependent increase in the number of immature neurons in the hippocampus. Infusion of 10 μg/day of IGF-1 produced detectable levels of hIGF-1 in the cortex and hippocampus and a concomitant increase in protein kinase B activation in the hippocampus. Both motor function and cognition were improved over 7 days post-injury in IGF-1-treated cohorts. Vehicle-treated brain-injured mice showed reduced hippocampal immature neuron density relative to sham controls at 7 days post-injury. In contrast, the density of hippocampal immature neurons in brain-injured mice receiving acute onset IGF-1 infusion was significantly higher than in injured mice receiving vehicle and equivalent to that in sham-injured control mice. Importantly, the neurogenic effect of IGF-1 was maintained with as much as a 6-h delay in the initiation of infusion. These data suggest that central infusion of IGF-1 enhances the generation of immature neurons in the hippocampus, with a therapeutic window of at least 6 h post-injury, and promotes neurobehavioral recovery post-TBI.
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Affiliation(s)
- Shaun W. Carlson
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky
| | - Kathryn E. Saatman
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky
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14
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Vousooghi N, Sadat‐Shirazi M, Safavi P, Zeraati R, Akbarabadi A, Makki SM, Nazari S, Zarrindast MR. Adult rat morphine exposure changes morphine preference, anxiety, and the brain expression of dopamine receptors in male offspring. Int J Dev Neurosci 2018; 69:49-59. [DOI: 10.1016/j.ijdevneu.2018.06.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 05/27/2018] [Accepted: 06/24/2018] [Indexed: 12/13/2022] Open
Affiliation(s)
- Nasim Vousooghi
- Department of NeuroscienceSchool of Advanced Technologies in Medicine, Tehran University of Medical SciencesTehranIran
- Research Center for Cognitive and Behavioral Sciences, Tehran University of Medical SciencesTehranIran
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical SciencesTehranIran
| | - Mitra‐Sadat Sadat‐Shirazi
- Department of NeuroscienceSchool of Advanced Technologies in Medicine, Tehran University of Medical SciencesTehranIran
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical SciencesTehranIran
| | - Payam Safavi
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical SciencesTehranIran
| | - Ramin Zeraati
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical SciencesTehranIran
| | - Ardeshir Akbarabadi
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical SciencesTehranIran
- Department of Veterinary MedicineGarmsar Branch, Islamic Azad UniversityGarmsarIran
| | - Seyed Mohammad Makki
- Department of PsychiatrySchool of Medicine, Shahid Beheshti University of Medical SciencesTehranIran
| | - Shahrzad Nazari
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical SciencesTehranIran
| | - Mohammad Reza Zarrindast
- Genetics Laboratory, Iranian National Center for Addiction Studies (INCAS), Tehran University of Medical SciencesTehranIran
- Department of PharmacologySchool of Medicine, Tehran University of Medical SciencesTehranIran
- Institute for Studies in Theoretical Physics and Mathematics, School of Cognitive SciencesTehranIran
- Institute for Cognitive Science StudiesTehranIran
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15
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Abstract
This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and CUNY Neuroscience Collaborative, Queens College, City University of New York, Flushing, NY 11367, United States.
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16
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Skupio U, Sikora M, Korostynski M, Wawrzczak-Bargiela A, Piechota M, Ficek J, Przewlocki R. Behavioral and transcriptional patterns of protracted opioid self-administration in mice. Addict Biol 2017; 22:1802-1816. [PMID: 27578564 DOI: 10.1111/adb.12449] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 08/10/2016] [Accepted: 08/11/2016] [Indexed: 12/31/2022]
Abstract
Chronic exposure to opioids induces adaptations in brain function that lead to the formation of the behavioral and physiological symptoms of drug dependence and addiction. Animal models commonly used to test these symptoms typically last less than two weeks, which is presumably too short to observe the alterations in the brain that accompany drug addiction. Here, we analyzed the phenotypic and molecular effects of nearly lifelong morphine or saccharin intake in C57BL/6J mice. We used multiple paradigms to evaluate the symptoms of compulsive drug intake: a progressive ratio schedule, intermittent access and a schedule involving a risk of punishment were programmed into an automated IntelliCage system. Gene expression profiles were evaluated in the striatum using whole-genome microarrays and further validated using quantitative polymerase chain reaction in the striatum and the prefrontal cortex. Mice voluntary self-administering morphine showed addiction-related behavioral pattern that included: higher motivation to work for a drug reward, increased reward seeking and increased craving. The analysis of molecular changes revealed a tolerance effect in the transcriptional response to morphine injection (20 mg/kg, ip), as well as some long-lasting alterations in gene expression profiles between the analyzed groups of animals. Interestingly, among the morphine-drinking animals, certain transcriptional profiles were found to be associated with alterations in behavior. In conclusion, our model represents a novel approach for investigating the behavioral and molecular mechanisms underlying opioid addiction. Prolonged morphine intake caused adaptive processes in the brain that manifested as altered behavior and transcriptional sensitivity to opioids.
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Affiliation(s)
- Urszula Skupio
- Department of Molecular Neuropharmacology, Institute of Pharmacology; Polish Academy of Sciences; Poland
| | - Magdalena Sikora
- Department of Molecular Neuropharmacology, Institute of Pharmacology; Polish Academy of Sciences; Poland
| | - Michal Korostynski
- Department of Molecular Neuropharmacology, Institute of Pharmacology; Polish Academy of Sciences; Poland
| | | | - Marcin Piechota
- Department of Molecular Neuropharmacology, Institute of Pharmacology; Polish Academy of Sciences; Poland
| | - Joanna Ficek
- Department of Molecular Neuropharmacology, Institute of Pharmacology; Polish Academy of Sciences; Poland
| | - Ryszard Przewlocki
- Department of Molecular Neuropharmacology, Institute of Pharmacology; Polish Academy of Sciences; Poland
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17
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Morphine exposure during early life alters thermal and mechanical thresholds in rats. Int J Dev Neurosci 2016; 60:78-85. [DOI: 10.1016/j.ijdevneu.2016.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/04/2016] [Accepted: 12/29/2016] [Indexed: 12/20/2022] Open
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18
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Thomas A, Miller A, Roughan J, Malik A, Haylor K, Sandersen C, Flecknell P, Leach M. Efficacy of Intrathecal Morphine in a Model of Surgical Pain in Rats. PLoS One 2016; 11:e0163909. [PMID: 27783629 PMCID: PMC5082666 DOI: 10.1371/journal.pone.0163909] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/17/2016] [Indexed: 01/01/2023] Open
Abstract
Concerns over interactions between analgesics and experimental outcomes are a major reason for withholding opioids from rats undergoing surgical procedures. Only a fraction of morphine injected intravenously reaches receptors responsible for analgesia in the central nervous system. Intrathecal administration of morphine may represent a way to provide rats with analgesia while minimizing the amount of morphine injected. This study aimed to assess whether morphine injected intrathecally via direct lumbar puncture provides sufficient analgesia to rats exposed to acute surgical pain (caudal laparotomy).In an initial blinded, randomised study, pain-free rats received morphine subcutaneously (MSC, 3mg.kg-1, N = 6), intrathecally (MIT, 0.2mg.kg-1, N = 6); NaCl subcutaneously (NSC, N = 6) or intrathecally (NIT, N = 6). Previously validated pain behaviours, activity and Rat Grimace Scale (RGS) scores were recorded at baseline, 1, 2, 4 and 8h post-injection. Morphine-treated rats had similar behaviours to NaCl rats, but their RGS scores were significantly different over time and between treatments. In a second blinded study, rats (N = 28) were randomly allocated to one of the following four treatments (N = 7): MSC, 3mg.kg-1, surgery; MIT, 0.2mg.kg-1, surgery; NIT, surgery; NSC, sham surgery. Composite Pain Behaviours (CPB) and RGS were recorded as previously. CPB in MIT and MSC groups were not significantly different to NSC group. MSC and MIT rats displayed significantly lower RGS scores than NIT rats at 1 and 8h postoperatively. RGS scores for MIT and MSC rats were not significantly different at 1, 2, and 8h postoperatively. Intraclass correlation value amongst operators involved in RGS scoring (N = 9) was 0.913 for total RGS score. Intrathecal morphine was mostly indistinguishable from its subcutaneous counterpart, providing pain relief lasting up to 8 hours in a rat model of surgical pain. Further studies are warranted to clarify the relevance of the rat grimace scale for assessing pain in rats that have received opioid analgesics.
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Affiliation(s)
- Aurelie Thomas
- Comparative Biology Centre, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Amy Miller
- School of Agriculture, Food and Rural Development, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Johnny Roughan
- Comparative Biology Centre, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Aneesa Malik
- Royal (Dick) School of Veterinary Studies, Edinburgh, United Kingdom
| | - Katherine Haylor
- School of Biomedical Sciences, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Charlotte Sandersen
- Clinique Vétérinaire Universitaire, Faculté de Médecine Vétérinaire, Université de Liège, Liège, Belgium
| | - Paul Flecknell
- Comparative Biology Centre, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Matthew Leach
- School of Agriculture, Food and Rural Development, Newcastle University, Newcastle upon Tyne, United Kingdom
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