The ventilatory control system and opioid-induced respiratory depression Humans are critically dependent on the cardiorespiratory control system for adequate uptake of oxygen and removal of CO 2 via the lungs [ 1 ]. Open in a separate window. Figure 1. Simple schematic representation of the ventilatory control system Information from peripheral and central chemoreceptors, the lungs and higher brain centers is integrated in brainstem respiratory centers, which through efferent pathways control motor neurons of the diaphragm and other respiratory muscles so that breathing is adapted to both metabolic and behavioral needs.
Figure 2. Reversal of opioid-induced respiratory depression by non-opioids Respiratory stimulants that act through non-opioid receptor systems are of real therapeutic benefit as they may restore breathing to an acceptable level or even prevent OIRD without affecting analgesia. Figure 3. Ampakines Ventilatory drive may be modulated by manipulation of glutamatergic and serotonergic neurotransmission in respiratory centers in the brainstem Figure 1 [ 26 ].
Serotonin receptor agonists Animal studies show that serotonin agonists increase respiratory drive via actions at 5HT1A, 5HT7, and 5HT4a receptors [ 1 , 33 ].
Primum non nocere above all, do no harm OIRD is a serious problem that requires our attention and a rapid solution. References 1. Incidence, reversal and prevention of opioid-induced respiratory depression. Plasticity of central chemoreceptors: Effect of bilateral carotid body resection on central CO 2 sensitivity.
PLoS One. Clinical Anesthesia. Fatal respiratory depression after multiple intravenous morphine injections.
Clin Pharmacokinet. Medication-assisted therapies — Tackling the opioid overdose epidemic. New Eng J Med. Okie S. A flood of opioids, a rising tide of deaths.
N Eng J Med. Opioid-related adverse events in surgical hospitalizations: Impact on cost and length of stay. Ann Pharmacother. Adverse drug reactions in hospital in-patients: A prospective analysis of patient episodes. Effect of opioid-related adverse events on outcomes in selected surgical patients. J Pain Palliat Care Pharmacother. Pattinson KTS. Opioids and the control of respiration.
Br J Anaesth. Modeling the non-steady-state respiratory effects of remifentanil in awake and propofol sedated healthy volunteers. Recurrent hypoxemia in children is associated with increased analgesic sensitivity to opiates. Recurrent hypoxia in rats during development increases subsequent respiratory sensitivity to fentanyl. High-inspired oxygen concentration further impairs opioid-induced respiratory depression. Tapentadol in cancer pain management: A prospective open-label study.
Curr Med Opin. Respiratory stimulant drugs in the post-operative setting. Resp Physiol Neurobiol. Naloxone reversal of morphine- and morphineglucuronide-indiced respiratory depression in healthy volunteers: A mechanism-based pharmacokinetic-pharmacodynamic modeling study.
The ventilatory stimulant doxapram inhibits TASK tandem pore K 2P potassium channel function but does not affect minimum alveolar concentration. Anesth Analg. Cotten JF. Bamagbade OA. Advantages of doxapram for post-ananesthesia recovery and outcomes in bariatric surgery patients with obstructive sleep apnea.
Eur J Anaesthesiol. Doxapram reduces alfentanil plasma concentrations associated with an increase in cardiac output [abstract] Anesthesiology.
A cysteine-rich motif confers hypoxia sensitivity to mammalian large conductance voltage and Ca-activated K BK channel alpha-subunits. Proc Natl Acad Sci. GAL, a new intravenous BK Ca -channel blocker, is well tolerated and stimulates ventilation in healthy volunteers.
San Francisco, CA: Oct , GAL, a new intravenous selective potassium-channel blocker, reverses opioid-induced respiratory depression with no impairment of opioid analgesia [abstract] Presented at 3rd Annual Meeting of the Society of Anesthesia and Sleep Medicine.
Two studies on reversal of opioid-induced respiratory depression by BK-channel blocker GAL in human volunteers. J Clin Invest. J Neurosci. Mitchell GS. Back to the future: Carbon dioxide chemoreceptors in the mammalian brain. Nat Neurosci. Ampakines alleviate respiratory depression in rats. Ampakine CX protects against fentanyl-induced respiratory depression and lethal apnea in rats. Using the anesthetized rabbit as our model, we measured phrenic nerve discharge as an index of respiratory rate and amplitude.
We compared control indices with discharges after the injection of morphine and after the injection of donepezil. Morphine-induced depression of respiratory rate and respiratory amplitude was partly antagonized by donepezil without any effect on blood pressure and end-tidal C0 2.
In the other experiment, apneic threshold PaC0 2 was also compared. Morphine increased the phrenic nerve apnea threshold but this was antagonized by donepezil.
These findings indicate that systemically administered donepezil partially restores morphine-induced respiratory depression and morphine-deteriorated phrenic nerve apnea threshold in the anesthetized rabbit.
Key terms: morphine, donepezil, rabbit, respiratory depression, Alzheimer's disease, cholinesterase inhibitor. Morphine is the mainstay of cancer pain and postoperative analgesic management, but its side effects can limit dosage and reduce quality of life Bowdle ; Chaney ; McNicol et al. Respiratory depression is potentially the most serious side effect induced by morphine and is of great concern to physicians McNicol et al.
This morphine-induced side effect can be treated with naloxone, an opioid receptor antagonist, but naloxone also inhibits morphine-induced analgesia Bowdle Therefore, anesthesiologists and pain clinicians seek new therapeutic strategies that can antagonize morphine-induced respiratory depression.
Numerous articles have proposed various candidates as antagonistic drugs for opiate-induced respiratory depression Weinstock et al. However, none of these have been applied to clinical practice thus far because most are experimental chemicals. Among these candidates, only physostigmine, an acetylcholinesterase inhibitor, is clinically used and can antagonize opiate-induced respiratory depression Weinstock et al.
Acetylcholine ACh is an excitatory neurotransmitter in central respiratory control Murakoshi et al. However, physostigmine has numerous disadvantages, e. Neostigmine, another commonly used acetylcholinesterase inhibitor, does not penetrate the blood-brain barrier Padmanabha Pillai et al.
A long-acting acetylcholinesterase inhibitor that can pass the blood-brain barrier might become one of the candidate drugs for reversing opiate-induced respiratory depression. Donepezil, a widely used Alzheimer's disease drug, is a long-acting synthetic drug designed to selectively and reversibly inhibit acetylcholinesterase Smith Doody Furthermore, it easily penetrates the blood-brain barrier and targets the brain.
Therefore, we hypothesized that donepezil would reverse morphine-induced respiratory depression in the anesthetized rabbit. This study was conducted in accordance with a protocol approved by the Animal care and Use Committee of Teikyo University School of Medicine. The experimental procedure has been described in detail elsewhere Kuwana and Natsui ; Okada et al In the preliminary study, these anesthetics did not change respiratory activity during 3 hours in the same conditions of the present study.
In our previous study, the combination of chloralose and urethane could maintain a stable depth of anesthesia for over 8 h Okada et al. The trachea was cannulated in the mid-cervical region for artificial respiration and there was continuous monitoring of the end-tidal C0 2 with a gas analyzer Respina 1H26, NEC San-Ei, Tokyo, Japan. The right femoral artery and vein were catheterized for arterial blood pressure measurement and intravenous injection.
After preparatory nerve surgery, the vagus and aortic nerves were cut bilaterally at the mid-cervical region. Muscle paralysis was induced with 0. Thereafter, the same dose of pancuronium bromide was administered hourly.
B Example of moderate body motion signal head motion, slow walking reducing the dominance from the thorax motion on the piezoelectric sensor. The algorithm developed for this work extracts breath rates with short-time autocorrelation functions 4 s to suppress aperiodic signal components from body motions.
Estimates are only made when signal energy is below a threshold, where body motion does not obscure the thorax pressure changes. To assess the limitations of extracting breath rates this way, the algorithm was applied to 19 simultaneous recordings about 19 total hours of data on mice with the plethysmography and piezoelectric sensors. For just the low activity intervals a little less than half the data there was a slight over estimation of 0.
For the application of the algorithm to this study, estimates were performed in the low to moderate activity regions and these values were averaged over much larger intervals to provide an average respiration rate every 12 min. This was used to obtain a baseline rate averaged over a full 24 h pretreatment and a stable estimate of percent respiratory depression post-treatment every 12 min. This interval was large enough so that even in high activity regions there were typically 30 or more intervals where estimates could be made and averaged together.
The resulting derived measures enabled a quantitative evaluation of respiratory depression, survival time and recovery time Fig. PiezoSleep output for a mouse that recovers and a mouse that fails to recover after opioid treatment. Baseline respiratory rate is first established for 24 h. Time 0, is the time at which morphine is administered. Respiratory depression is defined as the lowest percentage of baseline reached after morphine treatment purple dotted arrow.
For a mouse that recovers, the green vertical arrow indicates recovery time when the respiratory rate returns to baseline. For a mouse that does not recover, the red vertical arrow indicates survival time when breathing stops i.
A bracketing approach was used to construct a dose—response curve with a minimal number of mice. These traits are largely uncorrelated. Recovery time and survival time are mutually exclusive traits and each mouse can either recover or fail to recover, not both.
These values indicate that the traits are heritable and also amenable to genetic mapping. Strain- and sex-specific effect of morphine on respiratory sensitivity. The traits of recovery time or survival time are censored such that a mouse does not appear in both graphs as each mouse displays only one of these two phenotypes.
Empty bars indicate that no mice fell into this category i. Scatterplot of percent respiratory depression vs recovery time top right panel showing a weak correlation of R 2 of 0. Published data reveal a variety of morphine LD 50 values for mice.
Yoburn et al. Using this approach, survival curves by strain and sex were established Fig. The morphine LD 50 ranged from There was not a consistent sex bias up or down across all strains; instead, some LD 50 values were higher in females than males e. The morphine LD 50 by strain and sex. The morphine LD 50 was determined for each of the eight founder strains and sex using at least six mice in each group and at least three doses of morphine, with at least two doses flanking the LD A Logistic 2-paramater survival curves separated by strain and sex are shown at the top and composites of all strains separated by sex are shown at the bottom.
JMP To find genetic loci that influence OIRD, quantitative trait loci QTL mapping was performed on the respiratory phenotypes using the high diversity, high precision, DO mouse population. Of the DO mice entered into the study, 83 females, males recovered and 67 females, 40 males did not recover.
The quantitative metrics for respiratory response to morphine, including respiratory depression, recovery time and survival time, all show a continuum of phenotypic diversity Fig. Respiratory response to morphine in Diversity Outbred mice. The distribution of respiratory responses is shown for respiratory depression top panel , recovery time middle panel and survival time bottom panel.
A significant QTL was identified for respiratory depression, but no genome-wide significant QTLs were detected for recovery time or survival time using these sample sizes. For the respiratory depression trait, we identified a LOD 9.
The QTL is called Rdro1 respiratory depression, response to opioids 1. QTL mapping of respiratory depression in DO mice. B Allele effect plot of the LOD 9. Genetic mapping studies are used to identify regions of interest containing variants that influence complex traits. To identify the relevant genes involved in complex trait regulatory mechanisms, there must be evidence of genetic polymorphisms segregating in the population that either influence protein structure or gene expression and evidence of a biological mechanism of action connecting them to the trait, such as expression in a trait-relevant tissue.
We identified a While these SNPs remain candidates for regulation of the respiratory depression phenotype, we focused on coding SNPs because their impact is more readily predictable.
None of the coding SNPs are the type with the most deleterious effects, such as a stop loss, stop gain or coding region insertion frameshift. Two of the three changes serine to threonine at amino acid in Kmt2c and asparagine to aspartic acid at amino acid 29 in Speer4a occurred in residues that are not conserved across species.
This amino acid is located within a functional domain that is conserved in vertebrates Fig. Indeed, this change places the hydrophobic residue, which are generally buried internally, onto the surface of the protein. The 3D protein structure analysis Fig. A Multi-species alignment of the Ricin B lectin domain of GALNT11 showing that the SL mutation occurs in a domain conserved across multiple vertebrates, including humans, mice, rats, Xenopus , and zebrafish.
The 3D structure rendered showing secondary structure as a cartoon type with coloring as a rainbow from N- to C-terminus. In this study, we found heritable strain differences in the quantitative metrics of respiratory response to morphine, including respiratory depression, recovery time and survival time, using an advanced, high-throughput, behavioral phenotyping protocol. We further identified genomic loci involved in morphine-induced respiratory depression using an unbiased genetic approach.
Mapping these traits in the DO mice and evaluation of sequence variants and protein structure, followed by integrative functional genomic analysis in GeneWeaver, has allowed us to implicate Galnt11 as a candidate gene for respiratory depression in response to morphine. We identified specific inbred strains of mice that were more sensitive to morphine than other inbred strains of mice.
The traits of respiratory depression, recovery time and survival time were all shown to have a high degree of heritability. In determining our probe dose for the outbred population, we observed that the LD 50 for morphine differed by four-fold between these eight parental strains harboring 45 million SNPs, or an equivalent genetic variation as found in the human population.
The traits of respiratory depression, recovery time and survival time were largely independent traits, as seen by their lack of correlation. Strains such as AJ, which had the lowest LD 50 for both males and females, did not demonstrate the highest degree of respiratory depression, suggesting that factors other than respiratory depression may play a role in opioid overdose. The lack of correlation between percent respiratory depression and survival time suggest other mechanisms of death in conjunction with OIRD.
Dolinak suggests that other baseline characteristics, such as obstructive sleep apnea, obesity, heart disease and lung disease, make an individual more susceptible to opioid toxicity The presence of the alleles segregating in the DO population are encouraging for finding additional QTLs related to recovery time and survival time in larger cohorts and possibly using alternatative opioids. The mechanisms underlying sensitivity to morphine and fentanyl are known to differ in many respects and this same work should be performed for the more potent fentanyl.
Fentanyl has similarities to morphine with respect to the recruitment of intracellular signaling mechanisms but there are also key differences.
Only one study has looked at human opioid overdose risk, specifically by scoring overdose status and determining the number of times that medical treatment was needed in European American populations Human genes have thus been mapped to opioid use, opioid dependence and opioid overdose susceptibility but human studies are not able to assess opioid-induced respiratory depression, specifically the LD 50 of an opioid. Animal studies have allowed us the opportunity to assess the LD 50 of a drug in a variety of genetic backgrounds and then map those sources of variation.
These types of controlled exposure experiments cannot be conducted in humans for which exquisite control of environment is not feasible and prior exposure history is unknown. Our genetic approach of QTL mapping in the DO mouse population has allowed us to identify a genomic region containing no genes previously known to function in opioid pharmacodynamics or pharmacokinetic processes, or implicated in OUD. The genetically diverse structure of this population allows for the identification of narrow genomic intervals often with very few candidate genes.
This approach of using advanced mouse populations together with integrative functional genomics has been useful for the prioritization of candidate genes in a variety of different disciplines 62 , 63 , The identification of Galnt11 as functioning within the morphine respiratory response reveals a potential new target for therapeutic development.
GALNT11 is an N -acetylgalactosaminyltransferase that initiates O-linked glycosylation whereby an N -acetyl- d -galactosamine residue is transferred to a serine or threonine residue on the target protein. The lectin domain of GALNT11 is the portion that functions to recognize partially glycosylated substrates and direct the glycosylation at nearby sites.
This type of post-translational modification controls many phamacokinetic and pharmacodynamic processes as well as the regulation of delta opioid receptor OPRD1 membrane insertions as O-linked glycosylation is required for proper export of OPRD1 from the ER O-linked glycosylation is also required for opioid binding peptides, increasing their ability to cross the blood brain barrier The integrative functional analysis in GeneWeaver identified Hs6st2 36 , Fn1 37 , Lrp1 36 , and Sdc4 38 as glycosylation targets of Galnt Our findings demonstrate the initial mapping of a locus involved in OIRD in mice, for which the likely candidates do not act via the opioid receptor, thereby providing a potential new target for remedial measures.
Although it is through mouse genetic variation that we identified this gene, it should be noted that this gene or its glycosylation targets need not vary in humans to be a viable target mechanism for therapeutic discovery and development. Characterization of the role of Galnt11 and its variants along with other viable candidates will resolve the mechanism further, and continued mapping studies in larger populations will enable detection of additional loci for various aspects of the opioid-induced respiratory response.
These findings suggest that phenotypic and genetic variation in the laboratory mouse provides a useful discovery tool for identification of previously unknown biological mechanisms of OIRD. All mice were acquired from The Jackson Laboratory JAX and were housed in duplex polycarbonate cages and maintained in a climate-controlled room under a standard light—dark cycle lights on at 0, h.
Bedding was changed weekly and mice had free access to acidified water throughout the study. Louis, MO. A Nestlet and Shepherd Shack were provided in each cage for enrichment.
Mice were housed in same sex groups of three to five mice per cage. A mouse plethysmography chamber was built consisting of a ml plexiglass chamber with ports for air supply and pressure measurement, and end openings outfitted with rubber gaskets to create an airtight seal after closing.
A piezo film sensor was sealed into the bottom of the chamber for data collection with PiezoSleep software, with piezo signal sampling set at Hz. A differential pressure transducer Biopac measures the pressure difference between the plethysmography chamber and reference chamber sampled at Hz. Signal alignment was done through a simple correlation, which typically indicates time differences of several seconds.
The program graphically displays an overlay of the piezo and plethysmography signals for easy visual confirmation. A graphical breath rate overlay allows navigation to intervals of signal disagreement to inspect the signals at these areas.
Not all strains received all doses but each strain received at least three doses such that two flanked one above, one below the LD Individual testing is necessary due to the known enhanced lethality of cage mates during morphine exposure, which has been shown to affect survival The mice had access to food and water ad libitum while in the chamber.
The room was maintained on a h light:dark cycle. They remained in their chambers undisturbed until 24 h after injection. Whenever possible, complete balanced cohorts of the eight strains and both sexes were run during each of nine replicates of the experiment. The data acquisition computer, food and water were checked daily; otherwise, the mice remained undisturbed.
Breath rates were estimated from 4-s intervals in which animal activity dropped low i. The respiratory rate baseline consisted of the average respiratory rate over the first 24 h, which included both sleep and wake periods. Respiratory rate was then measured in the same way after injection of opioid.
These measures were then used to determine thresholds for obtaining the recovery time respiratory rate returns to baseline, see Fig. This dose was determined as the average LD 50 dose across the eight strains and two sexes, 16 samples. To test for difference in the respiratory depression, recovery time and survival time across the strains and sexes a linear model was fit, the full model was:. In all cases, the full model was fit and reduced by dropping non-significant interactions followed by main effects.
The LD 50 was calculated using the drc 3. A logistic regression model was fit, and a goodness of fit test based upon Bates and Watts 72 performed.
In addition, a regression model assuming equal LD 50 across strains was compared by chi square to an LD 50 assumed different across strains. To graph the data a non-linear 2-parameter model was fit in JMP Tail samples were collected at the conclusion of the experiment and all mice were genotyped using the Giga-MUGA genotyping array NeoGene.
Genotypes were imputed to a 69 K grid to allow for equal representation across the genome. Genotype probabilities were calculated according to the founder genotypes and then converted to allele probabilities.
We then interpolated allele probabilities into a grid of 69, evenly-spaced genetic intervals Sex and date of test were included as additive covariates. The significance thresholds were determined for each trait by permutation mapping The confidence interval around the peak makers was determined using Bayesian support intervals.
To determine the percent of variation accounted for by the QTL the mice were classified at the variant into one of eight states based on genotype probabilities of mice at that locus. Following this, a one-way ANOVA was fit to ascertain the strain variation relative to total variation towards estimating heritable variation at that locus. At each SNP location the eight allele state probabilities are collapsed to two state SNP probabilities and the Cox proportional hazards regression was performed by coxph function in the survival 3.
Based on the output of the log base e likelihood for the null model and for the alternative model with covariates and genotype probabilities , we took the difference of both log likelihoods and then divided by ln 10 to convert the results into the LOD scale. Next we identified those that were within protein coding region that were most deleterious. Differential coding sequence non-synonymous amino acid substitution SNPs Cn that differed between the high and low allele groups were identified.
The gene sets were overlapped using the Jaccard similarity and GeneSet graph tools In order to determine if the Cn SNPS were in areas of evolutionary conservation we aligned the sequence of several species. The Clustal Omega program was used with default parameters The transition matrix is Gonnet, gap opening penalty of six bits, gap extension of one bit.
Clustal-Omega uses the HHalign algorithm and its default settings as its core alignment engine In order to assess the functional sufficiency of Galnt11 as a candidate gene the literature was searched to identify genome-wide studies characterizing glycosylation targets of GALTN11, one study was identified 33 and these genes were added to the GeneWeaver Database GS Boscarino, J.
Risk factors for drug dependence among out-patients on opioid therapy in a large US health-care system. Addiction , — PubMed Google Scholar. Cicero, T. Increased use of heroin as an initiating opioid of abuse: Further considerations and policy implications. Schmid, C. Bias factor and therapeutic window correlate to predict safer opioid analgesics. Cell , Tomassoni, A. Multiple fentanyl overdoses—New Haven, Connecticut, June 23, Google Scholar.
Comer, S. Fentanyl: Receptor pharmacology, abuse potential, and implications for treatment. May, W.
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