Wide-range measurement of thermal preference : a novel method for detecting analgesics reducing thermally-evoked pain in mice

Background: Wide use of oxaliplatin as an antitumor drug is limited by severe neuropathy with pharmacoresistant cold hypersensitivity as the main symptom. Novel analgesics to attenuate cold hyperalgesia and new methods to detect drug candidates are needed. Methods: We developed a method to study thermal preference of oxaliplatin-treated mice and assessed analgesic activity of intraperitoneal duloxetine and pregabalin used at 30 mg/kg. A prototype analgesiameter and a broad range of temperatures (0-45 °C) were used. Advanced methods of image analysis (deep learning and machine learning) enabled us to determine the effectiveness of analgesics. The loss or reversal of thermal preference of oxaliplatin-treated mice was a measure of analgesia. Results: Duloxetine selectively attenuated cold-induced pain at temperatures between 0 and 10 °C. Pregabalintreated mice showed preference towards a colder plate of the two used at temperatures between 0 and 45 °C. Conclusion: Unlike duloxetine, pregabalin was not selective for temperatures below thermal preferendum. It influenced pain sensation at a much wider range of temperatures applied. Therefore, for the attenuation of cold hypersensitivity duloxetine seems to be a better than pregabalin therapeutic option. We propose wide-range measurements of thermal preference as a novel method for the assessment of analgesic activity in mice

Anticonvulsant activity of new derivatives 3-benzyl-pyrrrolidine-2,5-dione

Przedmiotem badań niniejszej pracy była ocena potencjalnej aktywności przeciwdrgawkowej nowych pochodnych 3-benzylopirolidyno-2,5-dionu w różnych modelach napadów padaczkowych u zwierząt. W tym celu wykonany został test maksymalnego wstrząsu elektrycznego (MES), test podskórnego podania pentetrazolu (s.c.PTZ) oraz test drgawek psychomotorycznych indukowanych prądem o częstotliwości 6 pulsów na minutę (test 6 Hz). Zaburzenia i wpływ na koordynację ruchową oceniono w teście pręta obrotowego (rotarod). Spośród przebadanych struktur, część związków wykazała potencjalną aktywność w dawce 300 mg/kg w teście MES, jednak nie udało się potwierdzić tej aktywności po redukcji dawki do 100 mg/kg. W teście podskórnego podania pentetrazolu najbardziej aktywnymi związkami okazały się: RS 133, RS 143 oraz RS 145, dla których został wyznaczony parametr ED50, na podstawie którego badane struktury można uszeregować według wzrastającej aktywności przeciwdrgawkowej: RS 133 < RS 143 < RS 145. Dodatkowo dla aktywnych struktur został wyznaczony parametr TD50 w teście rotarod, którego najwyższą wartość wykazywał związek RS 143, a najniższą RS 145.Dla wybranych struktur, które nie wykazały aktywności w żadnym z przeprowadzonych testów badających potencjalną aktywność przeciwdrgawkową, został wykonany test 6 Hz. Jedynie związek RS 142 wykazał aktywność przeciwdrgawkową w tym teście.The aim of the study was to evaluate anticonvulsant activity of new derivatives 3-benzyl-pyrrrolidine-2,5-dione in various animals models of seizures. For this purpose were used maximal electroshock test (MES), pentylenetetrazole induced seizure model (s.c.PTZ) and psychomotor seizure model induced current of frequency 6 pulses per minute (test 6 Hz). A minimal motor impairment of compounds was evaluated in the rotarod test.Among the tested structures, some of the compounds demonstrate the potential anticonvulsant activity at a dose of 300 mg/kg in the MES test, but failed to confirm this activity after reduction of the dose to 100 mg/kg. In the subcutaneous pentylenetetrazol test, the most active compounds were RS 133, RS 143 and RS 145, for which the ED50 values were determined. Based on the obtained results the compounds can be sorted by increasing anticonvulsant activity: RS 133 < RS 143 < RS 145. In addition, for the active structures the TD50¬ values were established in the rotarod test. The highest value was showed the compound RS 143, while the lowest value RS 145.For certain structures which have no activity in any of the tests investigating the potential anticonvulsant activity the 6 Hz test was carried out. Only compound RS 142 revealed anticonvulsant activity in this assay

Serotonergic Neurotransmission System Modulator, Vortioxetine, and Dopaminergic D2/D3 Receptor Agonist, Ropinirole, Attenuate Fibromyalgia-Like Symptoms in Mice

Fibromyalgia is a disease characterized by lowered pain threshold, mood disorders, and decreased muscular strength. It results from a complex dysfunction of the nervous system and due to unknown etiology, its diagnosis, treatment, and prevention are a serious challenge for contemporary medicine. Impaired serotonergic and dopaminergic neurotransmission are regarded as key factors contributing to fibromyalgia. The present research assessed the effect of serotonergic and dopaminergic system modulators (vortioxetine and ropinirole, respectively) on the pain threshold, depressive-like behavior, anxiety, and motor functions of mice with fibromyalgia-like symptoms induced by subcutaneous reserpine (0.25 mg/kg). By depleting serotonin and dopamine in the mouse brain, reserpine induced symptoms of human fibromyalgia. Intraperitoneal administration of vortioxetine and ropinirole at the dose of 10 mg/kg alleviated tactile allodynia. At 5 and 10 mg/kg ropinirole showed antidepressant-like properties, while vortioxetine had anxiolytic-like properties. None of these drugs influenced muscle strength but reserpine reduced locomotor activity of mice. Concluding, in the mouse model of fibromyalgia vortioxetine and ropinirole markedly reduced pain. These drugs affected emotional processes of mice in a distinct manner. Hence, these two repurposed drugs should be considered as potential drug candidates for fibromyalgia. The selection of a specific drug should depend on patient’s key symptoms

The microglial activation inhibitor minocycline, used alone and in combination with duloxetine, attenuates pain caused by oxaliplatin in mice

The antitumor drug, oxaliplatin, induces neuropathic pain, which is resistant to available analgesics, and novel mechanism-based therapies are being evaluated for this debilitating condition. Since activated microglia, impaired serotonergic and noradrenergic neurotransmission and overexpressed sodium channels are implicated in oxaliplatin-induced pain, this in vivo study assessed the effect of minocycline, a microglial activation inhibitor used alone or in combination with ambroxol, a sodium channel blocker, or duloxetine, a serotonin and noradrenaline reuptake inhibitor, on oxaliplatin-induced tactile allodynia and cold hyperalgesia. To induce neuropathic pain, a single dose (10 mg/kg) of intraperitoneal oxaliplatin was used. The mechanical and cold pain thresholds were assessed using mouse von Frey and cold plate tests, respectively. On the day of oxaliplatin administration, only duloxetine (30 mg/kg) and minocycline (100 mg/kg) used alone attenuated both tactile allodynia and cold hyperalgesia 1 h and 6 h after administration. Minocycline (50 mg/kg), duloxetine (10 mg/kg) and combined minocycline + duloxetine influenced only tactile allodynia. Seven days after oxaliplatin, tactile allodynia (but not cold hyperalgesia) was attenuated by minocycline (100 mg/kg), duloxetine (30 mg/kg) and combined minocycline and duloxetine. These results indicate a potential usefulness of minocycline used alone or combination with duloxetine in the treatment of oxaliplatin-induced pain

Phenylalanine-based AMPA receptor antagonist as the anticonvulsant agent with neuroprotective activity - in vitro and in vivo studies

Trying to meet the multitarget-directed ligands strategy, a series of previously described aryl-substituted phenylalanine derivatives, reported as competitive antagonists of &alpha;-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, were screened in vitro for their free-radical scavenging and antioxidant capacity in two different assays: ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity fluorescent (ORAC-FL) assays. The most active antioxidants 1 and 8 were further examined to evaluate their neuroprotective properties in vitro. In this study, compound 1 showed a significant neuroprotective effect against the neurotoxin 6-hydroxydopamine in neuroblastoma SH-SY5Y and IMR-32 cell lines. Both compounds also showed prevention from high levels of reactive oxygen species (ROS) in SH-SY5Y cells. Furthermore, the desired monoamine oxidase B (MAO-B) inhibition effect (IC50 = 278 &plusmn; 29 nM) for 1 was determined. No toxic effects up to 100 &micro;M of 1 and 8 against neuroblastoma cells were observed. Furthermore, in vivo studies showed that compound 1 demonstrated significant anticonvulsant potential in 6-Hz test, but in neuropathic pain models its antiallodynic and antihyperalgesic properties were not observed. Concluding, the compound 1 seems to be of higher importance as a new phenylalanine-based lead candidate due to its confirmed promise in in vitro and in vivo anticonvulsant activity