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Neuropathic pain is caused by a primary lesion, dysfunction, or transitory perturbation in the peripheral or central nervous system. In this study, we investigated the hesperidin antihyperalgesic effects alone or combined with diosmin in a model of neuropathic pain to corroborate a possible synergistic antinociceptive activity. Mechanical and thermal hyperalgesia were assessed in the aesthesiometer and plantar tests, respectively, after chronic constriction injury (CCI) model in rats receiving hesperidin (HS, 5 doses from 10 to 1000 mg/kg) alone or combined with diosmin (DS, 10 and 100 mg/kg) in comparison to gabapentin (31.6 mg/kg). UHPLC-MS analysis of cerebral samples was used to recognize the central concentrations of these flavonoids. Participation of different receptors was also investigated in the presence of haloperidol, bicuculline, and naloxone antagonists. Acute hesperidin administration significantly decreased mechanical and thermal hyperalgesia in CCI rats. Antihyperalgesic response of hesperidin, improved by a combination with diosmin (DS10/HS100) in both stimuli, was blockaded by haloperidol, bicuculline, and naloxone, but not WAY100635, antagonists. Both flavonoids were detected in brain samples. In conclusion, hesperidin alone and combined with diosmin produces antihyperalgesic response in the CCI model in rats. Antihyperalgesic effect of DS10/HS100 combination involves central activity partially modulated by D2, GABAA, and opioids, but not by 5-HT1A, receptors. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Brickellia cavanillesii (Asteraceae) (Cass.) A. Gray is one of the popular plants consumed in Central America and Mexico for the treatment of several diseases such as hypertension, diabetes and anxiety, among others. Aim of the study To determine the anxiolytic-like effect of B. Cavanillesii and the safety of its use through toxicological studies. Material and methods Anxiolytic-like effects of soluble-methanol extract of B. cavanillesii (MEBc) were evaluated in ambulatory activity (open-field test), hole-board test, cylinder of exploration, the elevated plus-maze and the potentiation of the sodium pentobarbital-induced hypnosis mice models. On the other hand, in vivo toxicological studies were conducted on acute and sub-acute mice models recommended by OECD. Active MEBc was subjected to phytochemical studies through conventional chromatographic techniques to isolate bioactive compounds. Results MEBc (100 mg/Kg) showed significant anxiolytic-like effect on animal model used (p<0.05). The phytochemical analysis of MEBc allowed the isolation of two major compounds nicotiflorin and acacetin, among others. Both compounds were found to be partially responsible for the anxiolytic-like effects. Moreover, a median lethal dose (LD 50 ) higher than 2000 mg/Kg was determined in mice and sub-acute oral administration of MEBc (100 mg/Kg) did not alter body weight, clinical chemistry parameters (ALT and AST) and it did not induce any toxic nor alteration in the liver, kidney and heart functions. Conclusions In current investigation, we have shown that MEBc has a wide range of pharmacology–toxicology patterns. The results support further investigation of MEBc as a potential anxiolytic phytomedicinal agent. [ABSTRACT FROM AUTHOR]

Salvia divinorum Epling & Játiva is a Mexican plant used not only in rituals but also in traditional medicine for pain relief. One of the most known bioactive compounds is salvinorin A, which acts centrally in kappa-type opioid receptors. Despite its traditional use as a medicinal plant, there is not enough scientific investigation to reinforce its potential as analgesic. In this study, Salvia divinorum antinociceptive activity was evaluated in experimental models of nociceptive pain; the writhing test and formalin-induced licking behavior in mice. Different Salvia divinorum extracts were prepared by maceration at room temperature in increased polarity (hexane, ethyl acetate and methanol). The ethyl acetate extract (EAEx) was chosen in order to be fractioned and to obtain a mixture of salvinorins. The antinociceptive effect of EAEx (3, 10, 30, and 100 mg/kg, i.p.) was compared with that of tramadol (a partial opioid agonist analgesic drug, 30 mg/kg, i.p.) and the mixture of salvinorins (30 mg/kg, i.p.). In addition, a participation of opioids (naloxone, NX 1 and/or 3 mg/kg, i.p.) and serotonin 5-HT 1A receptors (WAY100635, 0.32 mg/kg, i.p.) was investigated as possible inhibitory neurotransmission involved. As a result, the EAEx produced significant and dose-dependent antinociceptive effect concerning salvinorins constituents. This effect was blocked in the presence of NX and WAY100635 in the abdominal test, but only by NX in the formalin-induced licking behavior. Whereas, the effect of salvinorins mixture involved opioids and serotonin 5-HT 1A receptors. Data provide evidence of the potential of this species, where salvinorin A is in part responsible bioactive constituent involving participation of the opioids and/or 5-HT 1A serotonin receptors depending on the kind of pain model explored. Image 1 [ABSTRACT FROM AUTHOR]