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      Fluoroscopic Characterization of Colonic Dysmotility Associated to Opioid and Cannabinoid Agonists in Conscious Rats

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          Abstract

          Background/Aims

          Gastrointestinal adverse effects have a major impact on health and quality of life in analgesics users. Non-invasive methods to study gastrointestinal motility are of high interest. Fluoroscopy has been previously used to study gastrointestinal motility in small experimental animals, but they were generally anesthetized and anesthesia itself may alter motility. In this study, our aim is to determine, in conscious rats, the effect of increasing doses of 2 opioid (morphine and loperamide) and 1 cannabinoid (WIN 55,212-2) agonists on colonic motility using fluoroscopic recordings and spatio-temporal maps.

          Methods

          Male Wistar rats received barium sulfate intragastrically, 20–22 hours before fluoroscopy, so that stained fecal pellets could be seen at the time of recording. Animals received an intraperitoneal administration of morphine, loperamide, or WIN 55,212-2 (at 0.1, 1, 5, or 10 mg/kg) or their corresponding vehicles (saline, Cremophor, and Tocrisolve, respectively), 30 minutes before fluoroscopy. Rats were conscious and placed within movement-restrainers for the length of fluoroscopic recordings (120 seconds). Spatio-temporal maps were built, and different parameters were analyzed from the fluoroscopic recordings in a blinded fashion to evaluate colonic propulsion of endogenous fecal pellets.

          Results

          The analgesic drugs inhibited propulsion of endogenous fecal pellets in a dose-dependent manner.

          Conclusions

          Fluoroscopy allows studying colonic propulsion of endogenous fecal pellets in conscious rats. Our method may be applied to the noninvasive study of the effect of different drug treatments and pathologies.

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          Most cited references57

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          Opioids in chronic non-cancer pain: systematic review of efficacy and safety.

          Opioids are used increasingly for chronic non-cancer pain. Controversy exists about their effectiveness and safety with long-term use. We analysed available randomised, placebo-controlled trials of WHO step 3 opioids for efficacy and safety in chronic non-cancer pain. The Oxford Pain Relief Database (1950-1994) and Medline, EMBASE and the Cochrane Library were searched until September 2003. Inclusion criteria were randomised comparisons of WHO step 3 opioids with placebo in chronic non-cancer pain. Double-blind studies reporting on pain intensity outcomes using validated pain scales were included. Fifteen randomised placebo-controlled trials were included. Four investigations with 120 patients studied intravenous opioid testing. Eleven studies (1025 patients) compared oral opioids with placebo for four days to eight weeks. Six of the 15 included trials had an open label follow-up of 6-24 months. The mean decrease in pain intensity in most studies was at least 30% with opioids and was comparable in neuropathic and musculoskeletal pain. About 80% of patients experienced at least one adverse event, with constipation (41%), nausea (32%) and somnolence (29%) being most common. Only 44% of 388 patients on open label treatments were still on opioids after therapy for between 7 and 24 months. The short-term efficacy of opioids was good in both neuropathic and musculoskeletal pain conditions. However, only a minority of patients in these studies went on to long-term management with opioids. The small number of selected patients and the short follow-ups do not allow conclusions concerning problems such as tolerance and addiction.
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            P-glycoprotein in the blood-brain barrier of mice influences the brain penetration and pharmacological activity of many drugs.

            The mouse mdr1a (also called mdr3) P-GP is abundant in the blood-brain barrier, and its absence in mdr1a (-/-) mice leads to highly increased levels of the drugs ivermectin, vinblastine, digoxin, and cyclosporin A in the brain. We show here that the drugs loperamide, domperidone, and ondansetron are transported substrates for the mouse mdr1a P-GP and its human homologue MDR1. Phenytoin is a relatively weaker substrate for each, and the drugs haloperidol, clozapine, and flunitrazepam are transported hardly or not at all. Tissue distribution studies demonstrated that the relative brain penetration of radiolabeled ondansetron and loperamide (and their metabolites) is increased four- and sevenfold, respectively, in mdr1a (-/-) mice. A pilot toxicity study with oral loperamide showed that this peripherally acting antidiarrheal agent gains potent opiatelike activity in the central nervous system of mdr1a (-/-) mice. mdr1a (-/-) mice also showed increased sensitivity to neurolepticlike side effects of oral domperidone. These results point to the possible role that the drug-transporting P-GP(s) may play in the clinical use of many drugs, especially those with potential targets in the central nervous system.
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              Gastrointestinal transit measurements in mice with 99mTc-DTPA-labeled activated charcoal using NanoSPECT-CT

              Background Gastrointestinal (GI) disorders are commonly associated with chronic conditions such as diabetes, obesity, and hypertension. Direct consequences are obstipation or diarrhea as opposite aspects of the irritable bowel syndrome, and more indirectly, alteration of appetite, feeling of fullness, flatulence, bloatedness, and eventually leading to altered absorption of nutrients. Moreover, GI retention and passage times have been recognized as important factors in determining the release site and hence the bioavailability of orally administered drugs. To facilitate the understanding of physiological and pathological processes involved, it is necessary to monitor the gut motility in animal models. Here, we describe a method for studying the GI transit time using technetium-labeled activated charcoal diethylenetriaminepentaacetic acid (99mTc-Ch-DTPA) detected by single-photon emission computed tomography (SPECT). Methods Tc-DTPA was adsorbed onto activated charcoal and administered orally to trypan blue-tainted (n = 4) 129SvEv mice (50 to 80 MBq/animal, n = 11). The exact distribution and movement of radioactivity in the gastrointestinal tract was measured at intervals of 1, 3, 6, 12, and 22 h by SPECT-CT. In addition, in order to validate the imaging of GI transient time, loperamide (0.25 mg/animal, n = 3) was used to delay the GI transit. Results The transit time measured as the peak radioactivity occurring in the rectum was 6 to 7 h after gavaging of 99mTc-Ch-DTPA. After 1 h, the bolus had passed into the small intestine and entered the cecum and the colon. At 6 and 8 h, the cecum, the ascending, transverse, and descending colon, and the rectum showed significant labeling. Several pellets were stored in the rectum for defecation. After 22 h, little activity remained in the stomach and none was detected in the transverse colon or other GI locations. In contrast, 6 h after administration of loperamide, only the cecum and part of the transverse colon were labeled. After 22 h, both structures retained significant amount of label. This delay has been verified by non-radiolabeled dye trypan blue GI measurements (n = 4). Conclusion Here, we present the first non-invasive study of mouse GI transit time, allowing clear differentiation between vehicle- and loperamide-treated animals. This technique is useful for the investigation of GI motility in mice.
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                Author and article information

                Journal
                J Neurogastroenterol Motil
                J Neurogastroenterol Motil
                Journal of Neurogastroenterology and Motility
                Korean Society of Neurogastroenterology and Motility
                2093-0879
                2093-0887
                April 2019
                30 April 2019
                : 25
                : 2
                : 300-315
                Affiliations
                [1 ]Unidad de Dolor, Servicio de Anestesiología, Hospital General Universitario Gregorio Marañón, Madrid, Spain
                [2 ]Departamento de Ciencias Básicas de la Salud, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Alcorcón, Madrid, Spain
                [3 ]Unidad Asociada I+D+i al Instituto de Investigación en Ciencias de la Alimentación, CIAL (CSIC), Madrid, Spain
                [4 ]Unidad Asociada I+D+i al Instituto de Química Médica, IQM (CSIC), Madrid, Spain
                [5 ]Grupo de Excelencia Investigadora URJC-Banco de Santander-Grupo Multidisciplinar de Investigación y Tratamiento del Dolor (i+DOL), Madrid, Spain
                Author notes
                [* ]Correspondence: Raquel Abalo, PhD, Departamento de Ciencias Básicas de la Salud, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avda. de Atenas s/n, 28922 Alcorcón, Madrid, Spain Tel: +34-91-488-8854, Fax: +34-91-488-8955, E-mail: raquel.abalo@ 123456urjc.es

                Susana Díaz-Ruano and Ana E López-Pérez have contributed equally to this manuscript.

                Article
                jnm-25-300
                10.5056/jnm18202
                6474695
                30870877
                396a6bf2-2cd2-497c-a661-a6a24940f0d6
                © 2019 The Korean Society of Neurogastroenterology and Motility

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 03 December 2018
                : 01 February 2019
                : 12 February 2019
                Categories
                Original Article

                Neurology
                analgesics, opioids,cannabinoids,colonic motility,fluoroscopy,rats
                Neurology
                analgesics, opioids, cannabinoids, colonic motility, fluoroscopy, rats

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