Maternal separation affects the electrophysiological properties of Aδ-fibres and nociceptive behaviours in male and female mice

Aim: Early life adverse effects have been associated with an increased risk of suffering pain syndromes in adulthood. Although animal models are of great importance to study modifications of pain sensitivity, up to date the results obtained are contradicting due to the varied methodologies used. Therefore, the aim of the present study was to characterise, as a whole, possible modifications in visceral and somatic nociceptive responses in male and female ICR mice, submitted to two different protocols of maternal separation (MS), and possible modifications in the electrophysiological properties of peripheral nociceptive Aδ-primary afferents. Main methods: Male and female mice were submitted to 3 or 4–8 hr of daily MS from postnatal day (PND) 2–17 and early weaned. On PND 67 von Frey, hot plate and writhing tests were performed. Afterwards electrophysiological recordings were carried out, using the in vitro skin-saphenous nerve preparation in males. Key findings: The short separation protocol of MS did not modify nociceptive sensitivity; but when mice were separated from their dams for the long separation, mechanical pain thresholds were modified in male and female mice and visceral nociception was increased in female mice. Electrophysiological recordings showed that cutaneous Aδ-fibres were sensitised and their mechanotransduction properties were altered in both MS protocols. Significance: Although MS increases the activity and the mechanosensitivity of cutaneous Aδ-afferent fibres at both short and long periods of separation, only the longer interval of time induces nociceptive sensitivity alterations during adulthood. These results highlight the possible influence of a stress free environment during childhood to reduce nociceptive alterations in adulthood.Ministerio de Ciencia e Innovación, Grant/Award Number: SAF2012-40075-C02-0

Short-term stress significantly decreases morphine analgesia in trigeminal but not in spinal innervated areas in rats

Plenty information exists regarding the effects of chronic stress, although few data exist on the effects of short-lasting stressors, which would mimic daily challenges. Differences in craniofacial and spinal nociception have been observed, thus those observations obtained in spinally innervated areas cannot be directly applied to the orofacial region. Although, opioids are considered amongst the most effective analgesics, their use is sometimes hampered by the constipation they induce. Thus, our aims were to study if a short-lasting stressor, forced swim stress (FSS), modifies nociception, morphine antinociception and constipation in rats. Animals were submitted to 10–20 min of FSS for three days, nociception and gastrointestinal transit were studied 24 h after the last swimming session. Nociception and morphine (0.6–5 mg/kg) antinociception were evaluated in the formalin and hypertonic saline tests in the orofacial area and limbs. Morphine-induced modifications in the GI transit were studied through radiographic techniques. Naloxone was administered, before each swimming session, to analyse the involvement of the endogenous opioid system on the effect of stress. Overall, stress did not alter nociception, although interestingly it reduced the effect of morphine in the orofacial tests and in the inflammatory phase of the formalin tests. Naloxone antagonized the effect of stress and normalized the effect of morphine. Stress did not modify the constipation induced by morphine. Opioid treatment may be less effective under a stressful situation, whilst adverse effects, such as constipation, are maintained. The prevention of stress may improve the level of opioid analgesia.This work was supported by the Ministerio de Ciencia e Innovación of Spain (MINCINN. SAF2012-40075-C02-01)

Behavior and electrophysiology studies of the peripheral neuropathy induced by individual and co-administration of paclitaxel and oxaliplatin in rat

Aims: Antitumor agents, as taxanes and platinum compounds, induce peripheral neuropathies which can hamper their use for cancer treatment. The study of chemotherapy-induced neuropathies in humans is difficult because of ethical reasons, differences among administration protocols and intrinsic characteristics of patients. The aim of the present study is to compare the neuropathic signs induced by individual or combined administration of paclitaxel and oxaliplatin. Main methods: Oxaliplatin and paclitaxel were administered individually and combined to induce peripheral neuropathy in rats, sensory neuropathic signs were assessed in the hind limbs and orofacial area. The in vitro skin-saphenous nerve preparation was used to record the axonal activity of Aδ sensory neurons. Key findings: Animals treated with the combination developed mechanical allodynia in the paws and muscular hyperalgesia in the orofacial area, which was similar to that in animals treated with monotherapy, the latter also developed cold allodynia in the paws. Aδ-fibers of the rats treated with the combination were hyperexcited and presented hypersensitivity to pressure stimulation of the innervated skin, also similar to that recorded in the fibers of the animals treated with monotherapy. Significance: Our work objectively demonstrates that the combination of a platinum compound with a taxane does not worsen the development of sensorial neuropathies in rats, which is an interesting data to take into account when the combination of antitumor drugs is necessary. Co-administration of antitumor drugs is more effective in cancer treatment without increasing the risk of the disabling neuropathic side effects.This study was supported by the public institution: Ministerio de Ciencia e Innovación-MINCINN (SAF2012-40075-C02-01

May a sigma-1 antagonist improve neuropathic signs induced by cisplatin and vincristine in rats?

Background: The antineoplastic drugs cisplatin and vincristine induce peripheral neuropathies. The sigma-1 receptor (σ1R) is expressed in areas of pain control, and its blockade with the novel selective antagonist MR-309 has shown efficacy in nociceptive and neuropathic pain models. Our goal was to test whether this compound reduces neuropathic signs provoked by these antitumoural drugs. Methods: Rats were treated with cisplatin or vincristine to induce neuropathies. The effects of acute or repeated administration of MR-309 were tested on mechanical and thermal sensitivity, electrophysiological activity of Aδ-primary afferents in the rat skin–saphenous nerve preparation, and gastrointestinal or cardiovascular functions. Results: Rats treated with antitumourals developed tactile allodynia, while those treated with vincristine also developed mechanical hyperalgesia. These in vivo modifications correlated with electrophysiological hyperactivity (increased spontaneous activity and hyperresponsiveness to innocuous and noxious mechanical stimulation). Animals treated with cisplatin showed gastrointestinal impairment and those receiving vincristine showed cardiovascular toxicity. A single dose of MR-309 strongly reduced both nociceptive behaviour and electrophysiological changes. Moreover, its concomitant administration with the antitumourals blocked the development of neuropathic symptoms, thus restoring mechanical sensitivity, improving the impairment of feeding behaviour and gastrointestinal transit in the cisplatin-treated group along with ameliorating the altered vascular reactivity recorded in rats treated with vincristine. Conclusion: σ1R antagonist, MR-309, reduces sensorial and electrophysiological neuropathic signs in rats treated with cisplatin or vincristine and, in addition, reduces gastrointestinal and cardiovascular side effects. Significance: σ1R antagonism could be an interesting and new option to palliate antitumoural neuropathies.To Ivan Álvarez Rodríguez, Carmen Merino and Guadalupe Pablo for their technical support. Ministerio de Ciencia e Innovación-MICINN (SAF2012-40075- C02- 01) and Esteve, Barcelona, Spain, for their financial support.Peer Reviewe

Radiographic and histopathological study of gastrointestinal dysmotility in lipopolysaccharide-induced sepsis in the rat

Background: Sepsis is a highly incident condition in which a cascade of proinflammatory cytokines is involved. One of its most frequent consequences is ileus, which can increase mortality. Animal models such as that induced by systemic administration of lipopolysaccharide (LPS) are useful to deeply evaluate this condition. The effects of sepsis on the gastrointestinal (GI) tract have been explored but, to our knowledge, in vivo studies showing the motor and histopathological consequences of endotoxemia in an integrated way are lacking. Our aim was to study in rats the effects of sepsis on GI motility, using radiographic methods, and to assess histological damage in several organs. Methods: Male rats were intraperitoneally injected with saline or E. coli LPS at 0.1, 1, or 5 mg kg. Barium sulfate was intragastrically administered, and X-rays were performed 0–24 h afterwards. Several organs were collected for organography, histopathology, and immunohistochemistry studies. Key Results: All LPS doses caused gastroparesia, whereas changes in intestinal motility were dose-and time-dependent, with an initial phase of hypermotility followed by paralytic ileus. Lung, liver, stomach, ileum, and colon (but not spleen or kidneys) were damaged, and density of neutrophils and activated M2 macrophages and expression of cyclooxygenase 2 were increased in the colon 24 h after LPS 5 mg kg. Conclusions and Inferences: Using radiographic, noninvasive methods for the first time, we show that systemic LPS causes dose-, time-, and organ-dependent GI motor effects. Sepsis-induced GI dysmotility is a complex condition whose management needs to take its time-dependent changes into account.Comunidad de Madrid, Grant/Award Number: S-SAL/0261/2006 and S2010/BMD- 2308; Fundación Ibercaja- Universidad de Zaragoza, Grant/Award Number: JIUZ-2015- BIO- 02; Gobierno de Aragón, Grant/Award Number: B04_17R and B29_17R; Ministerio de Ciencia e Innovación, Grant/Award Number: SAF2012-40075-C02- 01; Ministeriode Ciencia, Innovación y Universidades, Grant/Award Number: AGL2017-82987-R and SAF2017-83120-C2- 1- R; Universidad Rey Juan Carlos-Banco de Santander, Grant/Award Number: Call 2020 (NACfightsCOVID-19

New cannabinoid receptor antagonists as pharmacological tool

Synthesis and pharmacological evaluation of a new series of cannabinoid receptor antagonists of indazole ether derivatives have been performed. Pharmacological evaluation includes radioligand binding assays with [H]-CP55940 for CB1 and CB2 receptors and functional activity for cannabinoid receptors on isolated tissue. In addition, functional activity of the two synthetic cannabinoids antagonists 18 (PGN36) and 17 (PGN38) were carried out in the osteoblastic cell line MC3T3-E1 that is able to express CB2R upon osteogenic conditions. Both antagonists abolished the increase in collagen type I gene expression by the well-known inducer of bone activity, the HU308 agonist. The results of pharmacological tests have revealed that four of these derivatives behave as CB2R cannabinoid antagonists. In particular, the compounds 17 (PGN38) and 18 (PGN36) highlight as promising candidates as pharmacological tools.This work was supported from Ministerio de Ciencia e Innovación under Grant RTI2018-096100B-100, Plan Nacional de I + D + I 2013-2016, ISCIII–FEDER (FIS16/00637), Plan de Ciencia, Tecnología e Innovación 2013-2017 and 2018-2022 del Principado de Asturias (GRUPIN14-028, IDI-2018-000152), RedInRen from ISCIII (RD16/0009/0017). Natalia Carrillo López was supported by GRUPIN14-028 and IDI-2018-000152

Changes in the diet composition of fatty acids and fiber affect the lower gastrointestinal motility but have no impact on cardiovascular parameters: In vivo and in vitro studies

Background: Food and diet are central issues for proper functioning of the cardiovascular (CV) system and gastrointestinal (GI) tract. We hypothesize that different types of dietary FAs affect CV parameters as well as GI motor function and visceral sensitivity. Methods: Male Wistar rats were fed with control diet (CTRL), diet supplemented with 7% soybean oil (SOY), SOY + 3.5% virgin coconut oil (COCO), and SOY + 3.5% evening primrose oil (EP) for 4 weeks. The content of insoluble fiber in CTRL was higher than in SOY, COCO, or EP. Body weight gain and food/water intake were measured. At day 28, biometric, biochemical, CV parameters, GI motor function (X-ray and colon bead expulsion test), and visceral sensitivity were evaluated. Changes in propulsive colonic activity were determined in vitro. The colon and adipose tissue were histologically studied; the number of mast cells (MCs) in the colon was calculated. Results: SOY, COCO, and EP had increased body weight gain but decreased food intake vs CTRL. Water consumption, biometric, biochemical, and CV parameters were comparable between groups. SOY increased the sensitivity to colonic distention. All groups maintained regular propulsive neurogenic contractions; EP delayed colonic motility (P < 0.01). SOY, COCO, and EP displayed decreased size of the cecum, lower number and size of fecal pellets, and higher infiltration of MCs to the colon (P < 0.001). Conclusions and Inferences: Dietary FAs supplementation and lower intake of insoluble fiber can induce changes in the motility of the lower GI tract, in vivo and in vitro, but CV function and visceral sensitivity are not generally affected.The funding was supported by the Medical University of Lodz (#50 2‐03/1‐156‐04/502‐14‐343‐17, #502‐03/1‐156‐04/502‐14‐343‐18 to PM and #503/1‐156‐04/503‐11‐001 to JF), Ministerio de Ciencia e Innovación (SAF2012‐40075‐C02‐01 to MIMF), and Ministerio de Ciencia, Innovación y Universidades (RTI2018‐101511‐B‐I00) and GEMD‐Allergan to RA . Universidad Rey Juan Carlos (Programa Propio de Fomento y Desarrollo de la Investigación, 2012) and Ministerio de Educación y Deporte (Subprograma de Movilidad, 2016: PRX17/00373) funded two research leaves to RA enjoyed at Dr Costa's laboratory (Flinders University of South Australia). L. Blanco had a contract by Consejería de Educación, Juventud y Deporte from Comunidad de Madrid and Fondo Social Europeo (PEJ15/BIO/TL‐0580)

Promising biomedical subcutaneous delivery system in opioid disaccustom process: In vitro/in vivo evaluation of naloxone microparticles on antagonist effect of morphine

The addiction induced by the misuse of opioids, is not only a public health emergency but also a social and economic welfare. The main therapy is based on opioid antagonists. Oral and injectable naltrexone administration is the most widely used, presenting some inconveniences: poor patient adherence to the oral daily dosing schedule, cases of hepatitis and clinically significant liver dysfunction. This study proposes the in vitro e in vivo evaluation of anti-opioid properties of naloxone loaded-poly(lactic-co-glycolic) acid microparticles (NX-MP). In previous studies, NX-MP showed in vitro sustained naloxone release for one week at least. Our results demonstrate the in vitro efficacy of the NX-MP antagonizing for 7 days the morphine effect in SH-SY5Y cells and myenteric plexus-longitudinal muscle preparations isolated from guinea-pig ileum. The in vivo evaluation of the NX-MP was carried out in mice testing the antagonism of the antinociceptive effect of morphine. Results showed that subcutaneous administration of NX-MP blocked the morphine effect. The results of this work suggest that the subcutaneous administration of NX-MP enhances naloxone therapeutic efficacy as non-addictive medication and could be a promising alternative to naltrexone. Furthermore, the dose of NX-MP can be adapted to the patient necessities. It would be an interesting advantage to treat opioid-addiction.This research was partially funded by Universidad Complutense de Madrid Research Group (910939) and by Plan Nacional sobre Drogas, Gobierno de Espan

Indazolylketones as new multitarget cannabinoid drugs

Multitarget cannabinoids could be a promising therapeutic strategic to fight against Alzheimer's disease. In this sense, our group has developed a new family of indazolylketones with multitarget profile including cannabinoids, cholinesterase and BACE-1 activity. A medicinal chemistry program that includes computational design, synthesis and in vitro and cellular evaluation has allowed to us to achieve lead compounds. In this work, the synthesis and evaluation of a new class of indazolylketones have been performed. Pharmacological evaluation includes functional activity for cannabinoid receptors on isolated tissue. In addition, in vitro inhibitory assays in AChE/BuChE enzymes and BACE-1 have been carried out. Furthermore, studies of neuroprotective effects in human neuroblastoma SH-SY5Y cells and studies of the mechanisms of survival/death in lymphoblasts of patients with Alzheimer's disease have been achieved. The results of pharmacological tests have revealed that some of these derivatives (5, 6) behave as CB2 cannabinoid agonists and simultaneously show BuChE and/or BACE-1 inhibition.The authors gratefully acknowledge the financial support of Ministerio Español de Economía y Competitividad (CTQ2015- 66313-R) and would like to thank to Guadalupe Pablo and Carmen Merino for their excellent technical assistant. The work of MLC was supported by the Centre for Biomedical Research on Neurodegenerative Diseases (CIBERNED). GV was supported by a fellowship from SENECYT (Ecuador). Work dedicated in memoriam to Mercedes González Hormaizteguy, a great women scientist and wonderful personPeer Reviewe