Project description:Nociceptive response belongs to a basic animal behavior facilitating adaptability and survival upon external or internal stimuli. Fish, similarly to higher vertebrates, also possess nociceptive machinery. Current protocols involving procedures performed on adult zebrafish including heart cryoinjury do not, however, take into account the adverse effects including pain that may potentially arise from these methodologies. Here, we assess the effect of two analgesics, lidocaine and morphine, followed after the heart cryoinjury in zebrafish. Monitoring swimming behaviour together with histology and gene expression analysis at the single cell level using scRNA sequencing and RNAscope fluorescent in situ hybridization technology, we show morphine, but not lidocaine, significantly improves animal welfare 6 hours post-cryoinjury, without impairing heart regeneration process. Altogether, morphine should be considered as the analgesic of choice to reduce post-surgical pain in adult zebrafish.
Project description:Preclinical studies suggest that parental exposure to drugs of abuse such as opioids can have profound and long-lasting effects on reward processing and drug sensitivity across generations. However, little is known about the impact of long-term paternal morphine exposure on sensitivity to morphine-derived antinociception in offspring. We developed a novel sub-second pain scale with statistical modeling and machine learning to measure mechanical nociception in Long Evans and Sprague Dawley male and female rats. Next, we used this rat pain scale with a multigenerational paternal morphine exposure paradigm to determine whether chronic paternal morphine exposure impacts pain sensitivity in offspring. Finally, we used RNA sequencing to identify potential molecular correlates of sire exposure to morphine on offspring. Surprisingly, we found that von Frey hair filaments (VFHs), the most commonly-used noxious mechanical stimuli to test pain sensitivity, are not painful to rats as measured by this novel rat pain scale. Male progeny produced from morphine-treated sires did not exhibit any baseline changes in sensitivity to noxious mechanical stimuli but had greater sensitivity to the antinociceptive properties of morphine. Changes in gene expression within the periaqueductal gray, including primary members of the RGS family of proteins, were identified that may play a role in modified sensitivity to morphine within offspring. These findings reveal nuanced responses to VFHs that should be considered in future pain studies and demonstrate that long-term paternal exposure to morphine increases sensitivity to morphine-derived analgesia in the subsequent male generation.
Project description:Analyse of gene expression modification after chronic analgesic treatment. The hypothesis tested in the present study was that oxycodone and morphine induced gene expression modification. Results provide important information to understand the analgesic effects of oxycodone as compared to morphine in a neuropathic pain model Total RNA obtained from DRG of neuropathic or control animals after oxycodone or morphine treatment
Project description:A great number of studies have investigated changes induced by morphine exposure in gene expression using several experimental models. In this study, we examined gene expression changes during chronic exposure to morphine during maturation and differentiation of zebrafish CNS. Our study identified different functional classes of genes and individual candidates involved in the mechanisms underlying susceptibility to morphine actions related to CNS development. These results open new lines to study the treatment of pain and the molecular mechanisms involved in addiction. We also found a set of zebrafish-specific morphine-induced genes, which may be putative targets in human models for addiction and pain processes. Zebrafish embryos were divided into two experimental groups: control embryos and embryos at 5 hpf exposed to 10 nM morphine and collected at 24 hpf (covering the complete embryogenesis). Morphine was administered to the embryos in their water environment, i.e., diluted in E3 embryonic medium. The exposition to begun at the stage of 5 hpf (end of blastula) is continuous, in order to study the chronic effects of the exposure to drug. Microarray experiments were performed using six replicates for each condition, which contained the RNA of approximately one hundred embryos to minimize the influence of potential individual differences between the animals and technical variation introduced by tissue preparation. We previously reported that a concentration of 10 nM morphine is the highest concentration that can be used without a toxic effect on the embryos, and close to 5% of the morphine diluted in the E3 medium is detected in the embryo.
Project description:A great number of studies have investigated changes induced by morphine exposure in gene expression using several experimental models. In this study, we examined gene expression changes during chronic exposure to morphine during maturation and differentiation of zebrafish CNS. Our study identified different functional classes of genes and individual candidates involved in the mechanisms underlying susceptibility to morphine actions related to CNS development. These results open new lines to study the treatment of pain and the molecular mechanisms involved in addiction. We also found a set of zebrafish-specific morphine-induced genes, which may be putative targets in human models for addiction and pain processes.
Project description:Opioids are widely used, effective analgesics to manage severe acute and chronic pain, although they have recently come under scrutiny because of epidemic levels of abuse. While these compounds act on numerous central and peripheral pain pathways, the neuroanatomical substrate for opioid analgesia is not fully understood. By means of single-cell transcriptomics and manipulation of morphine-responsive neurons, have identified an ensemble of neurons in the rostral ventromedial medulla (RVM) that regulates mechanical nociception in mice. Among these, forced activation or silencing of excitatory RVMBDNF projection neurons mimicked or completely reversed morphine-induced mechanical antinociception, respectively, via a brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB)-dependent mechanism and activation of inhibitory spinal galanin-positive neurons. Our results reveal a specific RVM-spinal circuit that scales mechanical nociception whose function confers the antinociceptive properties of morphine.
Project description:Critically ill preterm infants experience multiple stressors while hospitalized. Morphine is commonly prescribed to ameliorate their pain and stress. We hypothesized that neonatal stress will have a dose-dependent effect on hippocampal gene expression, and these effects will be altered by morphine treatment. Male C57BL/6 mice were exposed to 5 treatment conditions between postnatal day 5 and 9: 1) Control, 2) mild stress + saline, 3) mild stress + morphine, 4) severe stress + saline and 5) severe stress + morphine. Hippocampal RNA was extracted and analyzed using Affymetrix Mouse Gene 1.0 ST Arrays. Single gene analysis and gene set analysis were used to compare groups with validation by qPCR. Stress resulted in enrichment of genes sets related to fear response, oxygen carrying capacity and NMDA receptor synthesis. Morphine downregulated gene sets related to immune function. Stress plus morphine resulted in enrichment of mitochondrial electron transport gene sets, and down-regulation of gene sets related to brain development and growth. We conclude that neonatal stress alone influences hippocampal gene expression, morphine alters a subset of stress-related changes in gene expression and influences other gene sets. Stress plus morphine show interaction effects not present with either stimulus alone. These changes may alter neurodevelopment. Male mice were exposed to 5 treatment conditions between postnatal day (P)5 and P9 (n=3/group), with birth recorded as P1. Litters were culled to n=7 maximum per dam. Groups included: 1) Untreated controls (CC), 2) mild stress + saline (MSS), 3) mild stress + morphine (MSM), 4) severe stress + saline (SSS) and 5) severe stress + morphine (SSM).
Project description:Analyse of gene expression modification after chronic analgesic treatment. The hypothesis tested in the present study was that oxycodone and morphine induced gene expression modification. Results provide important information to understand the analgesic effects of oxycodone as compared to morphine in a neuropathic pain model