Antioxidant, Analgesic and CNS Depressant Activities of Commelina diffusa Burm. f.

Commelina diffusa Burm. f. is a member of Commelinaceae family, which is widely grown in crop land and treated as a weed. This plant has several important medicinal properties which have not been studied extensively. In this study, the crude powder of C. diffusa whole plant was extracted with 95% ethanol and different solvent fractions (n-hexane, chloroform and methanol) were prepared from the crude extract by solvent-solvent partitioning. All these plant samples were subjected to bioassays for evaluating the antioxidant, central analgesic, peripheral analgesic and CNS depressant activities. The crude extract and its methanol soluble fraction showed mild free DPPH scavenging property with IC50 values of 98.49- and 84.77-μg/ml, respectively as compared to the standard ascorbic acid (IC50 = 2.67 μg/ml). In the analgesic activity test, the n-hexane fraction of C. diffusa at doses of 200- and 400-mg/kg body weight exhibited significant (p<0.05) central analgesic activity (tail flick test) in mice. Similarly, all the test samples showed statistically significant (p<0.05) reduction in abdominal writhing induced by acetic acid. C. diffusa showed significant CNS depressant activity which was measured by ‘open field test’ and ‘hole cross test’. Considering the potential bioactivities, the plant materials can be further studied elaborately to explore the activities of the purified compounds to aid in future drug development. Dhaka Univ. J. Pharm. Sci. 20(2): 159-166, 2021 (December)

The Human SCN10AG1662S Point Mutation Established in Mice Impacts on Mechanical, Heat, and Cool Sensitivity

The voltage-gated sodium channel NAV1.8 is expressed in primary nociceptive neurons and is involved in pain transmission. Mutations in the SCN10A gene (encoding NAV1.8 channel) have been identified in patients with idiopathic painful small fiber neuropathy (SFN) including the SCN10AG1662S gain-of-function mutation. However, the role of this mutation in pain sensation remains unknown. We have generated the first mouse model for the G1662S mutation by using homologous recombination in embryonic stem cells. The corresponding Scn10aG1663S mouse line has been analyzed for Scn10a expression, intraepidermal nerve fiber density (IENFD), and nociception using behavioral tests for thermal and mechanical sensitivity. The Scn10aG1663S mutants had a similar Scn10a expression level in dorsal root ganglia (DRG) to their wild-type littermates and showed normal IENFD in hindpaw skin. Mutant mice were more sensitive to touch than wild types in the von Frey test. In addition, sexual dimorphism was observed for several pain tests, pointing to the relevance of performing the phenotypical assessment in both sexes. Female homozygous mutants tended to be more sensitive to cooling stimuli in the acetone test. For heat sensitivity, male homozygous mutants showed shorter latencies to radiant heat in the Hargreaves test while homozygous females had longer latencies in the tail flick test. In addition, mutant males displayed a shorter reaction latency on the 54°C hot plate. Collectively, Scn10aG1663S mutant mice show a moderate but consistent increased sensitivity in behavioral tests of nociception. This altered nociception found in Scn10aG1663S mice demonstrates that the corresponding G1662 mutation of SCN10A found in SFN patients with pain contributes to their pain symptoms.

Acute toxicity, anti-inflammatory, analgesic and antipyretic effects of aqueous and hydroethanolic extracts of Brenania brieyi (Rubiaceae)

Brenania brieyi (Rubiaceae) is widely used in traditional Congolese medicine in the treatment of many pathologies that are manifested by inflammation, pain and fever. The objective of this study was to study the acute toxicity as well as to evaluate the antipyretic, analgesic and anti-inflammatory effects of the aqueous and hydro-ethanolic extracts of Brenania brieyibark on models of pyrexia, algesia and inflammation induced in rodents. The aqueous extract of Brenania brieyidoes not cause any mortality up to the dose of 4000 mg/kg, but promotes a slight increase in body weight. From 2000 mg/kg, the signs of toxicity observed were the significant decrease in mobility as well as the loss of alertness. At doses of 100 and 200 mg/kg, aqueous and hydro-ethanolic Brenania brieyiextracts showed a very significant anti-inflammatory effect (***p< 0.001) on edemas induced by carrageenin (1%), formaldehyde (2.5%) and histamine (1 mg/mL), greater than that of diclofenac at 10 mg/kg. At 200 mg/kg, both extracts showed a very significant analgesic effect (***p< 0.001), greater than that of paracetamol 100 mg/kg against pain induced by acetic acid 0.6% and formaldehyde 2.5%. Brenania brieyiwas slightly effective in the tail flick test. Brewer's yeast-induced hyperthermia was reduced by both extracts. However, the hydro-ethanolic extract proves to be more effective than the aqueous extract in all the tests carried out. These pharmacological effects would be related to the presence of alkaloids, tannins, flavonoids, anthraquinones, oses and saponosides.

Analgesic activity of Hydroalcholic extract of Achyranthes aspera leaves on animal model

Achyranthes aspera L. (Family: Amaranthaceae) is widely used as a medicinal plant. The hydroalcholic extract of Achyranthes aspera L. leaves was screened for its analgesic activity. The dose (200 mg/kg) was tested for analgesic activity using hot plate and Tail flick test in albino mice. The hydroalcholic extract of Achyranthes aspera L. leaves showed maximum analgesic activity in hot plate at reaction time 120 min (7.40±0.08) and tail flick method at reaction time 120 min (6.9±0.06). These study suggest that the hydroalcholic extract of Achyranthes aspera L. could be considered as potential analgesic agent.

MiR-140-5p inhibits morphine tolerance in rats by targeting TLR4

Purpose: To determine the influence of miR-140-5p on morphine tolerance in rats.Methods: Sprague-Dawley (SD) rats were randomly divided into morphine tolerance (MT) and saline control (NS) groups, respectively. Rats in MT group were injected with 10 μL (10 μg) morphine twice daily for seven consecutive days while those in NS group were administered the equivalent volume of normal saline. The maximum effect of morphine (MPE) was computed from tail-flick test results. MiR-140-5p mimics and toll-like receptor 4 (TLR4) lentivirus were transfected separately or co-transfected into model rats. MiR-140-5p and TLR4 expression were determined by quantitative real-time polymerase chain reaction (RT-qPCR) or western blotting. Dual-luciferase reporter assay was used to verify the target relationship between miR-140-5p and TLR4.Results: The expression of miR-140-5p was decreased, while the expression of TLR4 increased in morphine-tolerant rats (p < 0.05). TLR4 was a target of miR-140-5p. At 24 and 48 h after injection, MPE clearly increased and TLR4 expression was reduced under miR-140-5p overexpression or TLR4 knockdown (p < 0.05). Moreover, there were no significant changes in MPE or levels of TLR4 when miR-140-5p and TLR4 were co-transfected into morphine-tolerant rats.Conclusion: MiR-140-5p inhibits morphine resistance in rats via targeted regulation of TLR4 expression. These provide a theoretical basis for the clinical management of morphine tolerance.

Mucoadhesive, Thermoreversible Hydrogel, Containing Tetracaine-Loaded Nanostructured Lipid Carriers for Topical, Intranasal Needle-Free Anesthesia

Recent advances have been reported for needle-free local anesthesia in maxillary teeth by administering a nasal spray of tetracaine (TTC) and oxymetazoline, without causing pain, fear, and stress. This work aimed to assess whether a TTC-loaded hybrid system could reduce cytotoxicity, promote sustained permeation, and increase the anesthetic efficacy of TTC for safe, effective, painless, and prolonged analgesia of the maxillary teeth in dental procedures. The hybrid system based on TTC (4%) encapsulated in nanostructured lipid carriers (NLC) and incorporated into a thermoreversible hydrogel of poloxamer 407 (TTCNLC-HG4%) displayed desirable rheological, mechanical, and mucoadhesive properties for topical application in the nasal cavity. Compared to control formulations, the use of TTCNLC-HG4% slowed in vitro permeation of the anesthetic across the nasal mucosa, maintained cytotoxicity against neuroblastoma cells, and provided a three-fold increase in analgesia duration, as observed using the tail-flick test in mice. The results obtained here open up perspectives for future clinical evaluation of the thermoreversible hybrid hydrogel, which contains TTC-loaded NLC, with the aim of creating an effective, topical, intranasal, needle-free anesthesia for use in dentistry.

Effect of adjuvant drugs on the analgesic activity of opioid morphine analgesics and compound RU-1205

Introduction: Adjuvant medications can be used to increase the analgesic effect of opioid analgesics, reduce the manifestation of side effects, and also for premedication. This paper provides information on the effect of clonidine, haloperidol, metocloparmide, diazepam, midazolam on opioid analgesics: - morphine and the selective kappa-opioid agonist compound RU-1205. Materials and methods: A probable interaction between RU-1205, morphine and adjuvant drugs in pain behaviors was carried out on the model of somatogenic pain. 95 male mice received either RU-1205 (5 mg/kg, i.p.) and morphine (1 mg/kg, i.p.) separately or in combination with haloperidol (0.45 mg/kg, i.p.); midazolam (0.3 mg/kg, i.p.); diazepam (1 mg/kg, i.p.); metoclopramide (5 mg/kg, i.p.), and clonidine (1 mg/kg, i.p.). The analgesic effect was assessed by tail flick test. Registration of the latent period of the reaction was carried out 30, 60 and 90 minutes after the adjuvant drug administration. Results: When studying the interaction with morphine, it was found that clonidine, haloperidol and metoclopramide enhanced the effects; diazepam offset them, and midazolam had no affect on the analgesic properties. In the course of the studies, RU-1205 showed an increase in analgesic activity when combined with clonidine, a slight increase with midazolam, and a decrease when co-administered with diazepam. Haloperidol had no influence on the effect of RU-1205, while metoclopramide both potentiated and reduced the analgesic effect. Discussion: Pharmacodynamic and pharmacokinetic interactions of RU-1205 with an α2AR agonist, benzodiazepine receptor agonists, D2P antagonist, and σ-receptor blocker were established. Conclusion: The presented data make it possible to more accurately formulate ideas about the localization and action mechanism of the kappa-agonist of opioid receptors, the compound RU-1205.

Preparation and In Vivo Evaluation of a Lidocaine Self-Nanoemulsifying Ointment with Glycerol Monostearate for Local Delivery

Lidocaine, a commonly used local anesthetic, has recently been developed into a number of ointment products to treat hemorrhoids. This study examined its efficient delivery to the dermis through the pharmaceutical improvement of hemorrhoid treatment ointments. We attempted to increase the amount of skin deposition of lidocaine by forming a nanoemulsion through the self-nanoemulsifying effect that occurs when glycerol monostearate (GMS) is saturated with water. Using Raman mapping, the depth of penetration of lidocaine was visualized and confirmed, and the local anesthetic effect was evaluated via an in vivo tail-flick test. Evaluation of the physicochemical properties confirmed that lidocaine was amorphous and evenly dispersed in the ointment. The in vitro dissolution test confirmed that the nanoemulsifying effect of GMS accelerated the release of the drug from the ointment. At a specific concentration of GMS, lidocaine penetrated deeper into the dermis; the in vitro permeation test showed similar results. When compared with reference product A in the tail-flick test, the L5 and L6 compounds containing GMS had a significantly higher anesthetic effect. Altogether, the self-nanoemulsifying effect of GMS accelerated the release of lidocaine from the ointment. The compound with 5% GMS, the lowest concentration that saturated the dermis, was deemed most appropriate.

Effect of Hydroalcoholic Extract of Hyssop on Acute Pain in Male Rats Using Tail Flick Test

Background: Iranian traditional medicine uses hyssop (Hyssopus officinalis) as an effective medicinal plant to reduce pain and inflammation in different diseases. Although the anti-inflammatory effect of this plant is proved, there is no study into its analgesic effects. Thus, this study aimed to investigate the analgesic effect of the hydroalcoholic extract from hyssop flowers and upper branches. Methods: This experimental study was conducted on 66 male rats that were divided into several groups including a saline control group, the groups of different doses of hyssop extract, morphine positive control group, the groups of hyssop extract plus morphine, and the most effective dose of the hyssop extract plus naloxone. All injections were administered intraperitoneally, and the pain was measured through the tail flick test. Results: Based on the results, 600 mg/kg was the most effective analgesic hyssop extract dose, and the most analgesic effect was observed at 45 minutes after administration. In addition, the administration of the most effective extract dose (600 mg/kg) plus morphine significantly improved the analgesic effects of morphine (P<0.001). Finally, the administration of naloxone plus the most effective extract dose (600 mg/kg) significantly reduced the analgesic effect of the extract (P<0.05). Conclusion: Overall, the hydroalcoholic extract of hyssop has analgesic effects that are probably applied through opioid receptors.

Paroxetine effects on morphine analgesic tolerance in rats

Objectives To alleviate different pain intensities, morphine administration has been extensively used. However, prolonged administration of morphine leads to a progressive decline of its analgesic effect which limits their overall utility. Morphine tolerance is considered as a challenging issue for the treatment of both acute and chronic pain. We conducted this study in rats to investigate the effect of paroxetine on morphine tolerance when used preemptively or after morphine tolerance had developed. Methods Male Wistar rats (weight 250–300 g, n=10) were used to evaluate the effects of paroxetine on tolerance to morphine. In order to induce tolerance, daily intraperitoneal injection of morphine (7 mg/kg) was done. After tolerance induction, a group of animals received intraperitoneal injection of 10 mg/kg paroxetine 30 min prior to each morphine dose. In another trial, to investigate the potential of paroxetine to prevent tolerance to morphine, animals were pretreated with 10 mg/kg paroxetine 30 min before morphine administration. In the control groups, 10 mL/kg of saline was injected. The behavioral test (tail-flick test) was done for all groups. Results Our data showed that paroxetine significantly reversed tolerance to morphine when used after tolerance induction (p<0.001). However, administration of paroxetine before occurrence of tolerance had no effect. Conclusions We conclude that paroxetine could decrease tolerance to morphine when used after the occurrence of morphine tolerance, while it was not able to prevent morphine tolerance when administered preemptively. Ethical committee number IRIB.SBMU.MSP.REC.1394.098.