Antinociceptive Activity of Trichilia catigua Hydroalcoholic Extract: New Evidence on Its Dopaminergic Effects

Trichilia catigua is a native plant of Brazil; its barks are used by some local pharmaceutical companies to prepare tonic drinks, such as Catuama. The present study was addressed to evaluate the effects of T. catigua hydroalcoholic extract in mouse nociception behavioral models, and to evaluate the possible mechanisms involved in its actions. Male Swiss mice were submitted to hot-plate, writhing and von Frey tests, after oral treatment with T. catigua extract (200 mg kg−1, p.o.). The extract displayed antinociceptive effect in all three models. For characterization of the mechanisms involved in the antinociceptive action of the extract, the following pharmacological treatments were done: naloxone (2.5 mg kg−1, s.c.), SR141716A (10 mg kg−1, i.p.), SCH23390 (15 μg kg−1, i.p.), sulpiride (50 mg kg−1, i.p.), prazosin (1 mg kg−1, i.p.), bicuculline (1 mg kg−1, i.p.) or dl-p-chlorophenylalanine methyl ester (PCPA, 100 mg kg−1, i.p.). In these experiments, the action of T. catigua extract was evaluated in the hot-plate test. The treatment with SCH23390 completely prevented the antinociceptive effect, while naloxone partially prevented it. The possible involvement of the dopaminergic system in the actions of T. catigua extract was substantiated by data showing the potentiation of apomorphine-induced hypothermia and by the prevention of haloperidol-induced catalepsy. In conclusion, the antinociceptive effects of T. catigua extract seem to be mainly associated with the activation of dopaminergic system and, to a lesser extent, through interaction with opioid pathway

Kinin B1 receptors mediate depression-like behavior response in stressed mice treated with systemic E. coli lipopolysaccharide

<p>Abstract</p> <p>Background</p> <p>Kinin B₁receptors are inducible molecules up-regulated after inflammatory stimuli. This study evaluated the relevance of kinin B₁receptors in a mouse depression behavior model.</p> <p>Methods</p> <p>Mice were exposed to a 5-min swimming session, and 30 min later they were injected with <it>E. coli </it>lipopolysaccharide (LPS). Depression-like behavior was assessed by determining immobility time in a tail suspension test. Different brain structures were collected for molecular and immunohistochemical studies. Anhedonia was assessed by means of a sucrose intake test.</p> <p>Results</p> <p>Our protocol elicited an increase in depression-like behavior in CF1 mice, as assessed by the tail-suspension test, at 24 h. This behavior was significantly reduced by treatment with the selective B₁receptor antagonists R-715 and SSR240612. Administration of SSR240612 also prevented an increase in number of activated microglial cells in mouse hippocampus, but did not affect a reduction in expression of mRNA for brain-derived neurotrophic factor. The increased immobility time following LPS treatment was preceded by an enhancement of hippocampal and cortical B₁receptor mRNA expression (which were maximal at 1 h), and a marked production of TNFα in serum, brain and cerebrospinal fluid (between 1 and 6 h). The depression-like behavior was virtually abolished in TNF<it>α </it>p55 receptor-knockout mice, and increased B₁receptor mRNA expression was completely absent in this mouse strain. Furthermore, treatment with SSR240612 was also effective in preventing anhedonia in LPS-treated mice, as assessed using a sucrose preference test.</p> <p>Conclusion</p> <p>Our data show, for the first time, involvement of kinin B₁receptors in depressive behavioral responses, in a process likely associated with microglial activation and TNFα production. Thus, selective and orally active B₁receptor antagonists might well represent promising pharmacological tools for depression therapy.</p

Antinociceptive Activity of Trichilia catigua Hydroalcoholic Extract: New Evidence on Its Dopaminergic Effects

Trichilia catigua is a native plant of Brazil; its barks are used by some local pharmaceutical companies to prepare tonic drinks, such as Catuama. The present study was addressed to evaluate the effects of T. catigua hydroalcoholic extract in mouse nociception behavioral models, and to evaluate the possible mechanisms involved in its actions. Male Swiss mice were submitted to hot-plate, writhing and von Frey tests, after oral treatment with T. catigua extract (200 mg kg −1 , p.o.). The extract displayed antinociceptive effect in all three models. For characterization of the mechanisms involved in the antinociceptive action of the extract, the following pharmacological treatments were done: naloxone (2.5 mg kg −1 , s.c.), SR141716A (10 mg kg −1 , i.p.), SCH23390 (15 μg kg −1 , i.p.), sulpiride (50 mg kg −1 , i.p.), prazosin (1 mg kg −1 , i.p.), bicuculline (1 mg kg −1 , i.p.) or dl-p-chlorophenylalanine methyl ester (PCPA, 100 mg kg −1 , i.p.). In these experiments, the action of T. catigua extract was evaluated in the hot-plate test. The treatment with SCH23390 completely prevented the antinociceptive effect, while naloxone partially prevented it. The possible involvement of the dopaminergic system in the actions of T. catigua extract was substantiated by data showing the potentiation of apomorphineinduced hypothermia and by the prevention of haloperidol-induced catalepsy. In conclusion, the antinociceptive effects of T. catigua extract seem to be mainly associated with the activation of dopaminergic system and, to a lesser extent, through interaction with opioid pathway

Pharmacological inhibition of CXCR2 chemokine receptors modulates paraquat-induced intoxication in rats.

Paraquat (PQ) is an agrochemical agent commonly used worldwide, which is allied to potential risks of intoxication. This herbicide induces the formation of reactive oxygen species (ROS) that ends up compromising various organs, particularly the lungs and the brain. This study evaluated the deleterious effects of paraquat on the central nervous system (CNS) and peripherally, with special attempts to assess the putative protective effects of the selective CXCR2 receptor antagonist SB225002 on these parameters. PQ-toxicity was induced in male Wistar rats, in a total dose of 50 mg/kg, and control animals received saline solution at the same schedule of administration. Separate groups of animals were treated with the selective CXCR2 antagonist SB225002 (1 or 3 mg/kg), administered 30 min before each paraquat injection. The major changes found in paraquat-treated animals were: decreased body weight and hypothermia, nociception behavior, impairment of locomotor and gait capabilities, enhanced TNF-α and IL-1β expression in the striatum, and cell migration to the lungs and blood. Some of these parameters were reversed when the antagonist SB225002 was administered, including recovery of physiological parameters, decreased nociception, improvement of gait abnormalities, modulation of striatal TNF-α and IL-1β expression, and decrease of neutrophil migration to the lungs and blood. Taken together, our results demonstrate that damage to the central and peripheral systems elicited by paraquat can be prevented by the pharmacological inhibition of CXCR2 chemokine receptors. The experimental evidence presented herein extends the comprehension on the toxicodynamic aspects of paraquat, and opens new avenues to treat intoxication induced by this herbicide

Synergistic effects of celecoxib and bupropion in a model of chronic inflammation-related depression in mice.

This study was aimed to characterize the depression-like behaviour in the classical model of chronic inflammation induced by Complete Freund's Adjuvant (CFA). Male Swiss mice received an intraplantar (i.pl.) injection of CFA (50 µl/paw) or vehicle. Behavioural and inflammatory responses were measured at different time-points (1 to 4 weeks), and different pharmacological tools were tested. The brain levels of IL-1β and BDNF, or COX-2 expression were also determined. CFA elicited a time-dependent edema formation and mechanical allodynia, which was accompanied by a significant increase in the immobility time in the tail suspension (TST) or forced-swimming (FST) depression tests. Repeated administration of the antidepressants imipramine (10 mg/kg), fluoxetine (20 mg/kg) and bupropion (30 mg/kg) significantly reversed depression-like behaviour induced by CFA. Predictably, the anti-inflammatory drugs dexamethasone (0.5 mg/kg), indomethacin (10 mg/kg) and celecoxib (30 mg/kg) markedly reduced CFA-induced edema. The oral treatment with the analgesic drugs dipyrone (30 and 300 mg/kg) or pregabalin (30 mg/kg) significantly reversed the mechanical allodyinia induced by CFA. Otherwise, either dipyrone or pregabalin (both 30 mg/kg) did not significantly affect the paw edema or the depressive-like behaviour induced by CFA, whereas the oral treatment with dipyrone (300 mg/kg) was able to reduce the immobility time in TST. Noteworthy, CFA-induced edema was reduced by bupropion (30 mg/kg), and depression behaviour was prevented by celecoxib (30 mg/kg). The co-treatment with bupropion and celecoxib (3 mg/kg each) significantly inhibited both inflammation and depression elicited by CFA. The same combined treatment reduced the brain levels of IL-1β, as well as COX-2 immunopositivity, whilst it failed to affect the reduction of BDNF levels. We provide novel evidence on the relationship between chronic inflammation and depression, suggesting that combination of antidepressant and anti-inflammatory agents bupropion and celecoxib might represent an attractive therapeutic strategy for depression

Behavioral scores of nociception.

<p>Assessment of behavioral scores at 25 min (A) or 55 min (B) after each treatment. Data is plotted as the cumulative scores of nociception over 5 min. Each column represents the mean ± SEM of 4–18 animals per group. ^*p<0.05 and ^**p<0.01 significantly different from control (vehicle/saline) group; ^#p<0.05 and ^##p<0.01 significantly different from vehicle/paraquat group (PQ) (ANOVA followed by Bonferroni's post-hoc test).</p

Primer sequences for RT-qPCR experiments.

<p>According to ^aHanafy et al., 2012; ^bSingh et al., 2012; ^cKireev et al., 2012; ^dBonefeld et al., 2008.</p

Hematological analysis and lung neutrophil migration.

<p>Representative pictures showing the blood smear slides in (A) control (vehicle/saline) groups; (B) vehicle/paraquat (PQ)-treated animals; (C) SB225002 (1 mg/kg)/saline group; (D) SB225002 (3 mg/kg)/saline group; (E) SB225002 (1 mg/kg)/plus PQ group; (F) SB225002 (3 mg/kg)/plus PQ group. Effects of paraquat and SB225002 on the total blood cell counts (G) and neutrophil migration as assessed by MPO activity (H). Each column represents the mean ± SEM of 4–20 animals per group in blood cell counts and 3–12 animals per group in MPO activity. ^{**,⊥⊥,ΨΨ}p<0.01 indicate significant differences of neutrophils, lymphocytes, and immature cells in relation to control (vehicle/saline) group, respectively. ^#,§p<0.05; ^##,§§p<0.01 indicate significant differences of neutrophils and lymphocytes in relation to vehicle/plus PQ group, respectively. ^*p<0.05 indicates significant difference of MPO activity in relation to control (vehicle/saline) group; ^#p<0.05 indicates significant difference to vehicle/plus PQ group (ANOVA followed by Bonferroni's post-hoc test).</p

Evaluation of paraquat effects in the open-field test.

<p>(A) Number of crossed squares; (B) number of rearings; (C) facial grooming in s; (D) number of fecal boluses. Each column represents the mean ± SEM of 4–18 animals per group. ^*,§p<0.05; ^**,##,§§p<0.01 compared with the basal measurements of the same experimental group (ANOVA followed by Bonferroni's post-hoc test).</p

RT-qPCR analysis of inflammatory markers.

<p>Relative expression profiles of (A) <i>NF-κB1</i>, (B) <i>TNF-α</i>, (C) <i>IL-1β</i>, and (D) <i>COX-2</i>, assessed in the striatum after the 5^th paraquat treatment. Each column represents the mean ± SEM, 3–4 samples of striatum. ^*p<0.05 compared with control (vehicle/saline) group (ANOVA followed by Bonferroni's post-hoc test).</p