Pharmacological Evidence of Eugenia Brasiliensis Leaves in a Reserpine-Induced Fibromyalgia Model: Antinociceptive, Emotional, Anti-Inflammatory, and Neurotrophic Effects.

Fibromyalgia (FM) is a painful chronic condition that significantly impacts the quality of life, posing challenges for clinical management. Given the difficulty of understanding the pathophysiology and finding new therapeutics, this study explored the effects of a medicinal plant, E. brasiliensis, in an FM model induced by reserpine in Swiss mice. Animals were treated with saline 0.9% (vehicle), duloxetine 10 mg/kg (positive control), or hydroalcoholic extract of E. brasiliensis leaves 300 mg/kg (HEEb). Nociceptive parameters, as well as locomotion, motor coordination, strength, anxiety, and depressive-like behaviors, were evaluated for 10 days. After that, the brain and blood were collected for further analysis of cytokines (interleukin 1? and interleukin 6), brain-derived neurotrophic factor (BDNF), and the immunocontents of total and phosphorylated Tropomyosin receptor kinase B (TrkB). The results demonstrated that the acute and prolonged treatment with HEEb was able to reduce both mechanical and thermal nociception. It was also possible to observe an increase in the strength, without changing locomotion and motor coordination parameters. Interestingly, treatment with HEEb reduces anxious and depressive-like behaviors. Finally, we observed a reduction in inflammatory cytokines in the hippocampus of animals treated with HEEb, while an increase in BDNF was observed in the prefrontal cortex (PFC). However, no alterations related to total and phosphorylated TrkB receptor expression were found. Our study demonstrated the antinociceptive and emotional effects of HEEb in mice, possibly acting on neuroinflammatory and neurotrophic mechanisms. These data provide initial evidence about the E. brasiliensis potential for treating chronic pain.

Oral treatment with Berberine reduces peripheral nociception: Possible interaction with different nociceptive pathways activated by different allogeneic substances.

ETHNOPHARMACOLOGICAL RELEVANCE: Berberine was identified in extracts of Berberis ruscifolia Lam., a plant used in traditional medicine as an analgesic. Its presence may be involved in the reported pharmacological activity of this species. However, there is still a lack of scientific research concerning its analgesic activity in the peripheral nervous system. AIM OF THE STUDY: To investigate Berb-induced antinociception in the formalin test and to evaluate several pathways related to its pharmacological antinociceptive effects in chemical models of nociception in mice. MATERIALS AND METHODS: The antinociceptive activity of Berb was assessed by inducing the paw licking in mice with different allodynic agents. In the formalin test, the antiedematous and antithermal effect of Berb was evaluated simultaneously in the same experiment. Other nociceptive behavior produced by endogenous [prostaglandin E2 (PGE2), histamine (His), glutamate (Glu) or bradykinin (BK)] or exogenous [capsaicin (Caps) and cinnamaldehyde (Cin)] chemical stimuli, and activators as protein kinase A (PKA) and C (PKC), were also evaluated.The in vivo doses for p.o. were 3 and 30 mg/kg. RESULTS: Berb, at 30 mg/kg p.o., showed a significant inhibition of the nociceptive action in formalin in both phases being stronger at the inflammatory phase (59 ± 9%) and more active than Asp (positive control) considering the doses evaluated. Moreover, Berb inhibited the edema (34 ± 10%), but not the temperature in the formalin test. Regarding the different nociceptive signaling pathways evaluated, the most relevant data were that the administration of p.o. of Berb, at 30 mg/kg, caused significant inhibition of nociception induced by endogenous [His (72 ± 11%), PGE2 (78 ± 4%), and BK (51 ± 7%)], exogenous [Cap (68 ± 4%) and Cinn (57 ± 5%)] compounds, and activators of the PKA [(FSK (86 ± 3%)] and PKC [(PMA(86 ± 6%)] signaling pathway. Berb did not inhibit the nociceptive effect produced by Glu. CONCLUSION: The present study demonstrated, for the first time, the potential of Berb in several nociceptive tests, with the compound present in B. ruscifolia contributing to the analgesic effect reported for this species.

Drug repositioning: diacerein as a new therapeutic approach in a mice model of sciatic nerve injury.

BACKGROUND: Peripheral nerve injuries negatively impact the quality of life of patients, with no effective treatment available that accelerates sensorimotor recovery and promotes functional improvement and pain relief. The aim of this study was to evaluate the effects of diacerein (DIA) in an experimental mice model of sciatic nerve crush. METHOD: In this study, male Swiss mice were used, randomly separated into six groups as follows: FO (false-operated + vehicle); FO + DIA (false-operated + diacerein 30 mg/kg); SNI (sciatic nerve injury + vehicle); SNI + DIA in doses of 3, 10 and 30 mg/kg (sciatic nerve injury + treatment with diacerein in doses of 3-30 mg/kg). DIA or vehicle was administered 24 h after the surgical procedure, intragastrically, twice a day. The lesion of the right sciatic nerve was generated by crush. RESULTS: We found that the treatment of animals with DIA accelerated sensorimotor recovery of the animal. In addition, animals in the sciatic nerve injury + vehicle (SNI) group showed hopelessness, anhedonia, and lack of well-being, which were significantly inhibited by DIA treatment. The SNI group showed a reduction in the diameters of nerve fibers, axons, and myelin sheaths, while DIA treatment recovered all these parameters. In addition, the treatment of animals with DIA prevented an increase the levels of interleukin (IL)-1ß and a reduction in the levels of the brain-derived growth factor (BDNF). CONCLUSIONS: Treatment with DIA reduces hypersensitivity and depression like behaviors in animals. Furthermore, DIA promotes functional recovery and regulates IL-1ß and BDNF concentrations.

Toxicological and pharmacological effects of Eugenia brasiliensis Lam. (Myrtaceae) leaves in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Eugenia brasiliensis Lam., popularly known as "grumixama" or "Brazilian cherry", is widely used in folk medicine with astringent, diuretic, energizing, anti-rheumatic, and anti-inflammatory properties. AIM OF THE STUDY: Despite its traditional use, detailed toxicological studies of Eugenia brasiliensis are few. Thus, in the current study, we evaluate the toxicological effects of hydroalcoholic extract of Eugenia brasiliensis (HEEb) and its antinociceptive and anti-inflammatory activity. MATERIALS AND METHODS: We used male, and female Swiss mice. Acute toxicity study was performed following the Organization for Economic Cooperation and Development (OECD) guideline 425, and subacute toxicity was assessed following OECD guideline 407. We observed behavioral responses, in addition to hematological, biochemical, and histological evaluations. The antinociceptive and anti-inflammatory activity of HEEb were assessed using the Carrageenan-induced mechanical allodynia and paw edema model. Mechanical allodynia, levels of inflammatory cytokines, and oxidative damage were evaluated. RESULTS: The treatment with HEEb was not able to generate important toxicological alterations. Moreover, doses of 100 and 300 mg/kg of HEEb were able to reduce mechanical allodynia, paw edema, and inflammatory cytokines (TNF-α, IL-1ß, and IL-6), decrease malondialdehyde and increase superoxide dismutase enzyme activity in the paw. CONCLUSIONS: This study demonstrated that HEEb does not present important toxic effects. Additionally, an important antinociceptive, anti-inflammatory, and antioxidant potential were observed.

Antinociceptive effect and identification of berberine alkaloid in Berberis ruscifolia extracts.

ETHNOPHARMACOLOGICAL RELEVANCE: Aerial parts (leaves and stems) of Berberis ruscifolia Lam. are a usual preparation as an analgesic, anti-inflammatory, antimalarial, antibacterial, and digestive in folk medicine. However, there were no previous studies of its chemical composition and biological activity related to analgesic effects. THE OBJECTIVE OF THE STUDY: The evaluation of the anti-nociception of the infusion (I), the decoction (D), and the ethanolic extract (EE) obtained from aerial parts of B. ruscifolia and its main chemical constituent in them, in mouse models. MATERIAL AND METHODS: The chemical constituent of B. ruscifolia extracts was evaluated and quantified by LC-MS and HPLC methodology. The inhibition of nociception in mice was analyzed by formalin and acetic acid-induced contortions tests. Also, when the formalin test was performed to evaluate the antinociceptive activity, the inhibition of edema formation and the antipyretic effect of each extract were simultaneously evaluated in the same experiment. For the oral administration in the in vivo assays, doses ranging from 10 to 1000 mg/kg and 10-30 mg/kg were used for extract and the chemical compound, respectively. RESULTS: The presence of berberine (Berb) was identified in the three evaluated extracts where the EE showed the highest content of this compound getting a yield of 2%, while in the I and D, Berb is present at 0.2%. The three extracts promoted a reduction of the contortions induced by acetic acid, being observed in EE the highest activity with 63 ± 6% of significant inhibition of the nociceptive behavior at a dose of 300 mg/kg, while D significantly inhibited 32 ± 12% at the same dose and for I at a dose of 1000 mg/kg an inhibition of 44 ± 8% was observed. Likewise, in the formalin trial, I and EE reduced nociception at a dose of 1000 (31 ± 5%) and 300 (35 ± 3%) mg/kg, respectively in the neurogenic phase, while in the second phase of the experiment, all the extracts evaluated showed an antinociceptive effect, with significant inhibition of I of 54 ± 6% and D of 44 ± 5% at a dose of 1000 mg/kg and for EE showed a 63 ± 2% inhibition at a dose of 300 mg/kg being the one with the highest antinociceptive activity. These extracts showed no inhibition in temperature and formalin-injected paw edema formation when compared to the control. As for Berb, at a 30 mg/kg dose, it showed significant inhibition of 70 ± 5% in the acetic acid-induced contortion test. CONCLUSION: Altogether, the present results evidenced the analgesic properties of B. ruscifolia, scientific information presented for the first time, and also provided important knowledge not reported so far about the chemical composition of its extracts, by identifying the presence of Berb in them. Finally, we were able to conclude that the analgesic effect demonstrated by this medicinal plant is partly due to the presence of Berb.

Metformin improves neurobehavioral impairments of streptozotocin-treated and western diet-fed mice: Beyond glucose-lowering effects.

Brain insulin resistance has been pointed to as a possible link between diabetes and neuropsychiatric disorders; therefore, therapeutic approaches using anti-diabetic drugs to improve insulin levels or signaling could prevent type 1 (T1D) and type 2 diabetes mellitus (T2D)-induced brain dysfunction. The present study aimed to determine whether metformin exerts beneficial effects on metabolic and neurobehavioral outcomes in the streptozotocin (STZ)-induced T1D model and western diet (WD)-induced obesity model in male Swiss mice. T1D was induced by intraperitoneal injection of STZ (50 mg/kg, for five consecutive days). The animals were then treated daily with saline or metformin (200 mg/kg/day, oral gavage), and a battery of tests recapitulating different neurobehavioral anomalies related to anxiogenic/depressive-like phenotype was conducted after 18 days. WD-induced obesity was modeled in mice by high-fat and high-fructose diet (HFFD) feeding for 15 days. In the sequence, control and diet-induced obesity mice were treated daily with saline or metformin (200 mg/kg/day), and a battery of behavioral tests was performed after 17 days. STZ injection and WD feeding induced metabolic and neurobehavioral impairments in mice. Remarkably, metformin improved the metabolic and neurobehavioral parameters in WD-induced obesity mice. Moreover, metformin ameliorated STZ-induced neurobehavioral deficits while it failed to improve the associated metabolic impairments. The beneficial effects of metformin in STZ-induced neurobehavioral impairments were not mediated by improving peripheral insulin signaling. Our results suggest that conventional diabetes treatment could be repurposed to simultaneously improve neurobehavioral symptoms and diabetes.

Mood disorders are associated with the reduction of brain derived neurotrophic factor in the hypocampus in rats submitted to the hipercaloric diet.

Adipose tissue accumulation, resulting from the consumption of hypercaloric foods, can cause a dysfunction of the endocrine system. Such endocrine changes can influence the expression of various neurochemicals including brain-derived neurotrophic factor (BDNF) - associated with cognitive and emotional problems. Here, we investigated the effects of a hypercaloric diet on depression- and anxiety-like behaviors in young rats along with concomitant changes in BDNF expression levels in the hippocampus. Eight week-old Wistar rats (n = 20) were divided in: control diet (CD) group which received industrial food (n = 8) and hypercaloric diet (HD) group which received animal fat and soybean oil (n = 12). After 45 days on the diet, the animals were evaluated: body weight and blood biochemical analisys. Changes in mood disposition were evaluated using forced swim test and the elevated plus-maze, whereas hippocampal BDNF expression levels were quantified by ELISA. After 45 weeks, the CD group showed a significant increase in body weight relative to the HD group. However, the HD rats had a body fat percentage and exhibited increased level of the biochemical markers. Furthermore, the animals in the HD group presented increased immobility time in the forced swimming test, as well as reduced response to plus-maze test suggesting a depression- and anxiety-like emotional state. In addition, the HD group also showed lower BDNF expression levels in the hippocampus. This study demonstrates that a hypercaloric diet induced increase in adipose tissue concentration in young rats was associated with reduced hippocampal BDNF expression and resulted in an increase in depression- and anxiety-like behaviors. Graphical abstract.

Root bark of Discaria americana attenuates pain: A pharmacological evidence of interaction with opioidergic system and TRP/ASIC channels.

ETHNOPHARMACOLOGICAL RELEVANCE: Discaria americana (Rhamnaceae) root bark infusion have been used in traditional medicine as antipyretic, tonic, ameliorative of stomach and skin diseases and diabetes. This study was designed to investigate whether the methanolic extract of the root bark of Discaria americana (MEDa) exhibits antinociceptive effects in mice. Furthermore, it was investigated the involvement of the opioidergic system in MEDa mechanism of action as well the interactions with TRP/ASIC channels in its effect. MATERIALS AND METHODS: The antinociceptive effect of intra-gastric gavage (i.g.) of MEDa (0.3-300 mg/kg) was evaluated in mice subjected to acute chemical (acetic-acid, formalin, glutamate, capsaicin, cinnamaldehyde, and acidified saline) or thermal (hot plate) tests of pain. The involvement of opioid system was evaluated in the formalin test. A nonspecific effect of MEDa was observed by measuring locomotor activity and exploratory behavior in open field test. RESULTS: MEDa significantly reduced the number of writhing induced by acetic acid and inhibited the nociception in the two phases of formalin. These effects were inhibited by pretreatment with naloxone. The nociception induced by hot plate and intraplantar injection of glutamate, capsaicin, cinnamaldehyde and acidified saline were significantly inhibited by MEDa. Only the dose of 300 mg/kg altered the locomotor activity. CONCLUSIONS: Our results demonstrated, for the first time, that the methanolic extract of the root bark of Discaria americana presents antinociceptive effect in chemical and thermal stimuli and its analgesic properties can be due activation of the opioidergic system. These results support the use of Discaria americana in traditional medicine and demonstrate that this plant presents a therapeutic potential for the development of phytomedicines with antinociceptive profile.