Search Results (82)

Background: Chronic pain poses a major global health burden, often inadequately managed by conventional analgesics due to limited efficacy and side effects. In this context, plant-based therapies offer a promising alternative. This study aimed to evaluate the antioxidant and analgesic potential of four medicinal plants traditionally used for pain relief: Morus alba, Angelica archangelica, Valeriana officinalis, and Passiflora incarnata. Methods: Phytochemical analyses quantified total phenolic acid, flavonoid, and polyphenolic acid contents in the extracts. Antioxidant activity was assessed using the ABTS radical scavenging assay. Analgesic effects were evaluated in vivo using the hot-plate and tail-flick tests in mice treated for 14 days with plant extracts or paracetamol. Results: Morus alba showed the highest polyphenolic content and strongest antioxidant activity (IC₅₀ = 0.0695 mg/mL). In analgesic tests, Angelica archangelica demonstrated the most significant effect in the hot-plate test (72.2% increase in latency), while Valeriana officinalis had the highest efficacy in the tail-flick test (41.81%), exceeding paracetamol’s performance in that model. Conclusions: While antioxidant activity correlated with polyphenol content, analgesic effects appeared to involve additional mechanisms. These findings support the potential of Angelica archangelica and Valeriana officinalis as effective natural alternatives for pain relief. Full article

Primary dysmenorrhea (PD) is characterized by lower abdominal spasms and painful cramps during menstruation in females with a normal pelvic anatomy. Cymbopogon citratus (DC.) Stapf, commonly known as lemongrass, is consumed in the form of herbal tea around the world. It has been traditionally used for menstrual disorders in several communities. This study aims to evaluate the traditional use of C. citratus for its efficacy in alleviating the symptoms of PD. C. citratus extract (CcE) was chemically characterized using HPLC and GCMS, which indicated the presence of several phenolic compounds and long-chain fatty acids. The anti-inflammatory activity of CcE was assessed by COX-I, COX-II, and 5-LOX enzyme inhibition with IC₅₀ values of 143.7, 91.7, and 61.5 µg/mL, respectively, and showed good total antioxidant capacity and free radical scavenging activity. PD was induced in female Wistar rats by administering estradiol valerate followed by oxytocin to induce PD symptoms. CcE efficacy was assessed at 30, 100, and 300 mg/kg concentrations and compared with ibuprofen. CcE 300 mg/kg reduced abdominal contortions and inflammation in the rat uterus. The inflammatory (COX-II, TNFα and IL-10) and oxidative stress (TAC, TOS, MDA and SOD) markers in uterine tissue homogenate were also improved. An in vivo analgesic assessment through hot-plate, tail-flick, and acetic acid-induced writhing assays showed good analgesic activity by CcE, while ex vivo experiments described tocolytic effects in rat uterine muscles. CcE alleviates PD by its antioxidant, anti-inflammatory, analgesic, and tocolytic effects. Full article

Background/Objectives: Indomethacin (IND) is a widely used non-steroidal anti-inflammatory drug (NSAID) effective in managing pain and inflammation. However, its therapeutic use is often limited by gastrointestinal irritation and low bioavailability. This study aimed to evaluate the biocompatibility, release kinetics, and analgesic potential of IND-loaded chitosan (CHIT)-stabilized lipid vesicles (IND-ves) in comparison to free IND, focusing on their in vivo effects and impact on somatic nociceptive reactivity in mice. Methods: IND-ves were prepared using a molecular droplet self-assembly technique, followed by CHIT coating to enhance stability and control drug release. Mice were administered either free IND or IND-ves, and various physiological parameters, including liver and kidney function, oxidative stress markers, immune cell activity, and histopathological changes in key organs, were assessed. Plasma drug release kinetics and analgesic effects were evaluated using the tail-flick test. Results: Both IND and IND-ves demonstrated good biocompatibility, with no significant changes in hematological, biochemical, or immunological profiles. IND-ves exhibited a sustained release profile, with drug release initiating at 30 min and peaking at 3 h, while free IND displayed a rapid release and potential gastric mucosal damage. IND-ves did not induce oxidative stress or inflammation and maintained organ integrity, particularly protecting against gastric injury. Additionally, the prolonged release profile of IND-ves contributed to extended analgesic effects in the tail-flick test. Conclusions: CHIT-stabilized lipid vesicles offer a promising drug delivery system for IND, enhancing drug release, prolonging analgesic efficacy, and minimizing gastrointestinal irritation. These findings suggest that IND-ves could serve as a safer and more effective alternative for NSAID therapy. Full article

Hydrazones, characterized by their C=N–NH functional group, are promising candidates in medicinal chemistry due to their ability to interact with biological targets. This study evaluated the anti-inflammatory and analgesic properties of N-pyrrolylcarbohydrazide (1) and four pyrrole hydrazone derivatives (1A–D) in male Wistar rats (6 weeks old). Anti-inflammatory activity was assessed using a carrageenan-induced paw edema model, while formalin, tail flick, and paw withdrawal tests evaluated analgesia. Compound 1 exhibited dose-dependent anti-inflammatory activity. At 20 mg/kg, significant edema reductions were observed at the 2nd (p = 0.035) and 3rd hours (p = 0.022), while at 40 mg/kg, reductions remained significant at the 2nd (p = 0.008) and 3rd hours (p = 0.046). Compound 1A showed pronounced effects at 20 mg/kg at the 2nd (p = 0.005), 3rd (p < 0.001), and 4th hours (p = 0.004). Other compounds demonstrated minimal or no activity. Analgesic evaluation revealed that at 40 mg/kg, compound 1 significantly reduced paw-licking time in the second phase (p = 0.038). Compounds 1B, 1C, and 1D exhibited transient effects in the first phase only (p < 0.05). Compound 1A lacked significant analgesic activity. The findings suggest that structural modifications may enhance efficacy for broader therapeutic applications. Full article

Background/Objectives: Orally or intravenously administered acetaminophen experiences considerable liver first-pass elimination and may cause liver/kidney damage. This work examined the pharmacological effects of acetaminophen-loaded poly(lactic-co-glycolic acid) nanoparticles (AAP PLGA NPs) intranasally administered to mice rapidly entering high altitudes. Methods: AAP PLGA NPs were prepared using ultrasonication-assisted emulsification and solvent evaporation and characterized in terms of drug encapsulation efficiency and loading, in vitro and in vivo release behaviors, and toxicity to hippocampal neurons. In vivo fluorescence imaging was used to monitor the concentrations of AAP PLGA NPs (labeled with indocyanine green) in the brain and blood of the mice after intranasal administration. The effects of these NPs on the pain threshold in mice rapidly entering high altitudes were evaluated through hot plate and tail flick experiments. Results: The AAP PLGA NPs were found to be noncytotoxic, highly biocompatible and stable, with a drug encapsulation efficiency and loading capacity of 42.53% and 3.87%, respectively. The in vitro release of acetaminophen lasted for up to 72 h, and the release rate was ~82%. After intranasal administration in vivo, the drug release occurred slowly, and the drug was mainly concentrated in the brain. Compared with nonencapsulated acetaminophen, the intranasal administration of AAP PLGA NPs resulted in higher brain levels of the drug and delayed its elimination, thus increasing the pain threshold in mice rapidly entering high altitudes. Conclusions: The proposed strategy addresses the common problems of intranasal drug administration (low retention time and bioavailability) and paves the way for effective pain management in high-altitude environments. Full article

Background: Pain is a major clinical and socioeconomic problem worldwide. The available therapies are not always effective and are often associated with the multiple adverse effects that reduce their clinical application. Natural compounds are an important group of pharmaceuticals that may be used in pain management. We aimed to investigate the analgesic activity of the sanguinarine–chelerythrine from Coptis chinensis. Methods: The analgesic and anti-inflammatory activity of the sanguinarine–chelerythrine fraction of C. chinensis extract (SC 5 and 10 mg/kg), sanguinarine (SAN 1 and 2 mg/kg) and chelerythrine (CHEL 4 and 8 mg/kg) was assessed in tail flick and formalin tests. A microscopic and macroscopic examination of stomach mucosae was performed. TNFα and MMP-9 levels were measured with ELISA kits. Results: Morphine (MORF), CHEL and SC prolongated the tail withdrawal latency, with comparable analgesic activity between MORF and CHEL 8 mg/kg. MORF, CHEL 8 mg/kg, and SAN 2 mg/kg ameliorated the pain reaction in the neurogenic phase of the formalin test. In the inflammatory phase of the formalin test, all tested substances exerted analgesic activity. SAN, CHEL and SC additionally reduced TNFα and MMP-9 secretion. Conclusions: Our results confirmed analgesic effects of CHEL and SC with CHEL analgesic activity comparable to MORF. All investigated substances exerted significant anti-inflammatory activity without concomitant gastrotoxicity. Full article

Background/Objectives: Approximately one in five individuals will experience major depressive disorder (MDD), and 30% exhibit resistance to standard antidepressant treatments, resulting in a diagnosis of treatment-resistant depression (TRD). Historically, opium was used effectively to treat depression; however, when other medications were introduced, its use was discontinued due to addiction and other hazards. Recently, kappa opioid receptor (KOR) antagonism has been proposed as a potential mechanism for treating TRD. The main research question is whether commonly used psychotropic medications possess KOR antagonist properties and whether this characteristic could contribute to their efficacy in TRD. Methods: We investigated the antinociceptive effects of many psychotropic medications and their interactions with the opioid system. Mice were tested with a hotplate or tail-flick after being injected with different doses of these agents. Results: The antidepressants mianserin and mirtazapine (separately) induced dose-dependent antinociception, each yielding a biphasic dose–response curve. Similarly, the antidepressant venlafaxine produced a potent effect and reboxetine produced a weak effect. The antipsychotics risperidone and amisulpride exhibited a dose-dependent antinociceptive effect. The sedative–hypnotic zolpidem induced a weak bi-phasic dose-dependent antinociceptive effect. All seven psychotropic medications elicited antinociception, which was reversed by the non-selective opiate antagonist naloxone and, separately, by the kappa-selective antagonist Nor-BNI. Conclusions: Clinical studies are mandatory to establish the potential efficacy of augmentation of the treatment with antidepressants with these drugs in persons with treatment-resistant depression and the optimal dosage of medications prescribed. We suggest a possible beneficial effect of antidepressants with kappa antagonistic properties. Full article

Kappa opioid receptor (KOR) agonists have well-established antinociceptive effects. However, many KOR agonists have negative side effects, which limit their therapeutic potential. Some researchers have suggested that the development of biased agonists that preferentially stimulate KOR G-protein pathways over β-arrestin pathways may yield drugs with fewer adverse side effects. This was investigated in the current study. We describe the synthesis and characterization of three U50,488 analogues, 1, 2, and 3. We evaluated the acute and chronic antinociceptive effects of these compounds in mice using the warm-water tail flick assay and in a paclitaxel-induced neuropathic pain model. Side effects were investigated using open-field, passive wire hang, rotarod, elevated zero maze, conditioned place aversion, and whole-body plethysmography, with some tests being conducted in KOR or β-arrestin2 knock out mice. All compounds were highly potent, full agonists of the KOR, with varying signaling biases in vitro. In the warm-water tail withdrawal assay, these agonists were ~10 times more potent than U50,488, but not more efficacious. All KOR agonists reversed paclitaxel-induced neuropathic pain, without tolerance. Compound 3 showed no significant side effects on any test. Signaling bias did not correlate with the antinociceptive or side effects of any compounds and knockout of β-arrestin2 had no effect on U50,488-induced sedation or motor incoordination. These findings highlight the therapeutic potential of 3, with its lack of side effects typically associated with KOR agonists, and also suggest that G-protein signaling bias is a poor predictor of KOR agonist-induced side effects. Full article

The course and outcome of infection with the parasitic protozoa Leishmania major depends on the host immune response which, itself, depends mainly on the cytokine milieu, especially early in the infection. It is widely accepted that INF-γ, TNF-α, and IL-12 usually favor a protective response, while IL-4, IL-5, IL-10, and IL-13 favor a pathogenic one. These and other cytokines also play a major role in Leishmania-induced hyperalgesia via two possible pathways, one involving prostaglandins and the other sympathetic amines as final mediators, preceded by a cascade of cytokines, among which TNF-α seems to play a pivotal role via a still unclear mechanism of action. This study investigates the effects of anti-TNF-α antibody (Infliximab) on L. major-induced hyperalgesia in susceptible BALB/c mice using the hot plate and tail flicks tests, as well as the levels of many cytokines in the infected paws of mice using the ELISA technique. In addition, the parasite burden was assessed using the serial dilution method. Our results show that Infliximab can reduce the induced hyperalgesia, up-regulate TNF-α, IL-1β, and keratinocyte-derived chemokine (KC), and down-regulate IL-10 and IL-17 in the paws of infected mice. Infliximab may also have beneficial effects on the prognosis of cutaneous leishmaniasis by reducing the parasite burden. Full article

Opioid analgesic tolerance (OAT), among other central side effects, limits opioids’ indispensable clinical use for managing chronic pain. Therefore, there is an existing unmet medical need to prevent OAT. Extrasynaptic N-methyl D-aspartate receptors (NMDARs) containing GluN2B subunit blockers delay OAT, indicating the involvement of glutamate in OAT. Glycine acts as a co-agonist on NMDARs, and glycine transporters (GlyTs), particularly GlyT-1 inhibitors, could affect the NMDAR pathways related to OAT. Chronic subcutaneous treatments with morphine and NFPS, a GlyT-1 inhibitor, reduced morphine antinociceptive tolerance (MAT) in the rat tail-flick assay, a thermal pain model. In spinal tissues of rats treated with a morphine–NFPS combination, NFPS alone, or vehicle-comparable changes in µ-opioid receptor activation, protein and mRNA expressions were seen. Yet, no changes were observed in GluN2B mRNA levels. An increase was observed in glycine and glutamate contents of cerebrospinal fluids from animals treated with a morphine–NFPS combination and morphine, respectively. Finally, GlyT-1 inhibitors are likely to delay MAT by mechanisms relying on NMDARs functioning rather than an increase in opioid efficacy. This study, to the best of our knowledge, shows for the first time the impact of GlyT-1 inhibitors on MAT. Nevertheless, future studies are required to decipher the exact mechanisms. Full article

In addition to blood pathogen transmission, insects of the order Diptera affect livestock through visual and contact harassment; blood-feeders are responsible for painful bites and blood despoliation, generating behavioral modifications, anemia, and production losses. Knowledge of their economic impact is a basis for cost-effective control. Here, we measured the global impact of diptera insects by comparing two batches of six feeder cattle, one in the open air and the other protected by a mosquito net. The analytical data were insect density in the open air and, for feeder cattle, tail flick counts, hematocrit values (Ht), feed intake, feed conversion ratio (FCR), and live body weight gain (LBWG). Over a period of five months, the results showed significant losses in the LBWG of cattle exposed to insects, estimated at 8.0 ± 1.5 kg/month [2.7; 13.3], with a total loss reaching 40.0 ± 5.5 kg/head. Main diurnal insects were Stomoxys spp. and Musca crassirostris. There was a strong correlation between fly density and diurnal tail flicks. Night trapping and tail flicks showed a potentially important role of mosquitoes to be further explored. The Ht levels of exposed animals were 3–4% lower than those of controls. FCRs indicated that exposed animals needed 33% more dry matter intake/kg of LBWG. An economic assessment showed that dipterans were responsible for a 10–11% loss in LBWG during the main growing period of feeder cattle (10–15 months). A feedlot of 100 calves would register a total loss of USD 16,000 within 5 months, which appears to be an unexpectedly huge loss caused by dipterans. Investing part of this money into fly control would probably be beneficial. Full article

Background/Objectives: The antinociceptive and anti-inflammatory effects of a patent-pending ointment containing plant extracts from Eucalyptus globulus, Curcuma longa, Hamamelis virginiana, Echinacea purpurea, and Zingiber officinale were evaluated. Methods: Plant extracts were chemically characterized by gas chromatography–mass spectroscopy. The antinociceptive activity of the ointment was assessed using the hot plate, tail flick, and formalin tests, whereas the anti-inflammatory activity was measured using the acute and chronic TPA-induced ear edema tests. Mechanisms of action were evaluated using inhibitors from signaling pathways related to pain response and by using histological analysis and assessing the expression and activity of pro-inflammatory mediators. Results: The ointment showed antinociceptive and anti-inflammatory effects like those observed with diclofenac gel (1.16% v/v) and ketoprofen gel (2.5% v/v). The antinociceptive actions of the ointment are mediated by the possible participation of the opiodergic system and the nitric oxide pathway. The anti-inflammatory response was characterized by a decrease in myeloperoxidase (MPO) activity and by a reduction in ear swelling and monocyte infiltration in the acute inflammation model. In the chronic model, the mechanism of action relied on a decrease in pro-inflammatory mediators such as COX-2, IL-1β, TNF-α, and MPO. An in-silico study with myristic acid, one of the compounds identified in the ointment’s plant mixture, corroborated the in vivo results. Conclusions: The ointment showed antinociceptive activities mediated by the decrease in COX-2 and NO levels, and anti-inflammatory activity due to the reduction in IL-1β and TNFα levels, a reduction in MPO activity, and a decrease in NF-κB and COX-2 expression. Full article

Introduction: Cannabis sativa L. (CSL) extract has pain-relieving potential due to its cannabinoid content, so the effects of two CSL extracts on alleviating neuropathic pain were investigated in vivo. Methods and groups: Male Wistar rats (n = 130) were divided into groups and received vincristine (0.1 mg/kg) and gabapentin (60 mg/kg) to induce and relieve neuropathic pain or CSL extracts (D and B). The mRNA and protein expression of the cannabinoid receptors type 1 and 2 (CB1R, CB2R) were evaluated in the cerebral cortex, hippocampus, and lymphocytes. Behavioural tests (Tail-Flick and von Frey) were performed on all animals. Results: VK-induced neuropathic pain was accompanied by decreased CB1R protein level and CB2R mRNA expression in the cortex. Gabapentin relieved pain and increased CB1R protein levels in the hippocampus compared to the vincristine group. Hippocampus CB1R protein expression increased with the administration of extract D (10 mg/kg, 40 mg/kg) and extract B (7.5 mg/kg, 10 mg/kg) compared to VK group. In the cerebral cortex CSL decreased CB1R protein expression (10 mg/kg, 20 mg/kg, 40 mg/kg of extract B) and mRNA level (5 mg/kg, 7.5 mg/kg of extract B; 20 mg/kg of extract D) compared to the VK-group.CB2R protein expression increased in the hippocampus after treatment with extract B (7.5 mg/kg) compared to the VK-group. In the cerebral cortex extract B (10 mg/kg, 20 mg/kg) increased CB2R protein expression compared to VK-group. Conclusion: Alterations in cannabinoid receptor expression do not fully account for the observed behavioural changes in rats. Therefore, additional signalling pathways may contribute to the initiation and transmission of neuropathic pain. The Cannabis extracts tested demonstrated antinociceptive effects comparable to gabapentin, highlighting the antinociceptive properties of Cannabis extracts for human use. Full article

Lidocaine hydrochloride (HCl) 2% with 1:100,000 epinephrine (LW/E) is widely used to prevent pain during dental procedures and has been associated with injection sting, jittering effects, slow onset, and a bitter aftertaste. Since LW/E’s introduction in 1948, no significant modifications have been proposed. This study aims to design and characterize an improved dental lidocaine HCl injectable formulation without epinephrine (LW/O/E) via buffers, sweeteners, and amino acids. LW/O/E injections were prepared with pH and osmolality values of 6.5–7.0 and 590–610 mOsm/kg. Using the electronic tongue (ETongue), the LW/O/E injectable formulations were characterized for viscosity, injectability, and taste analysis. The results were compared with the LW/E control. In vivo efficacy and anesthetic duration of the samples were measured through radiant heat tail-flick latency (RHTFL) and hot plate (HP) tests and local toxicity was assessed after a single intra-oral injection in Sprague Dawley rats (SDR). The viscosity and injectability values of the LW/O/E samples were found to be comparable to the LW/E injection. ETongue taste analysis showed an improvement in bitterness reduction of the LW/O/E samples compared to the LW/E formulation. Toxicity studies of samples in SDR showed minor and transient signs of erythema/eschar and edema. Anesthetic duration via RHTFL and HP paw withdrawal latency time in SDR were found to be comparable for the LW/O/E Sample 3A and the LW/E injection (p < 0.05). In conclusion, the buffered, higher osmolality and reduced bitterness developed LW/O/E formulation (Sample 3A) could be considered a promising alternative to the LW/E formulation for dental use. Full article

The inhibition of soluble epoxide hydrolase (sEH) can reduce the level of dihydroxyeicosatrienoic acids (DHETs) effectively maintaining endogenous epoxyeicosatrienoic acids (EETs) levels, resulting in the amelioration of inflammation and pain. Consequently, the development of sEH inhibitors has been a prominent research area for over two decades. In the present study, we synthesized and evaluated sulfonyl urea derivatives for their potential to inhibit sEH. These compounds underwent extensive in vitro investigation, revealing their potency against human and mouse sEH, with 4f showing the most promising sEH inhibitory potential. When subjected to lipopolysaccharide (LPS)-induced acute lung injury (ALI) in studies in mice, compound 4f manifested promising anti-inflammatory efficacy. We investigated the analgesic efficacy of sEH inhibitor 4f in a murine pain model of tail-flick reflex. These results validate the role of sEH inhibition in inflammatory diseases and pave the way for the rational design and optimization of sEH inhibitors based on a sulfonyl urea template. Full article