Epiisopiloturine, an Alkaloid from Pilocarpus microphyllus, Attenuates LPS-Induced Neuroinflammation by Interfering in the TLR4/NF-κB-MAPK Signaling Pathway in Microglial Cells.

Neuroinflammation is present in the pathophysiological mechanisms of several diseases that affect the central nervous system (CNS). Microglia have a prominent role in initiating and sustaining the inflammatory process. Epiisopiloturine (EPI) is an imidazole alkaloid obtained as a by-product of pilocarpine extracted from Pilocarpus microphyllus (jaborandi) and has shown promising anti-inflammatory and antinociceptive properties. In the present study, we investigated the effects of EPI on the inflammatory response in microglial cells (BV-2 cells) induced by lipopolysaccharide (LPS) and explored putative underlying molecular mechanisms. Cell viability was not affected by EPI (1-100 µg/mL) as assessed by both LDH activity and the MTT test. Pretreatment with EPI (25, 50, and 100 µg/mL) significantly reduced the proinflammatory response induced by LPS, as observed by a decrease in nitrite oxide production and iNOS protein expression. EPI (25 µg/mL) reduced IL-6 and TNF-α production, by 40% and 34%, respectively. However, no changes were observed in the anti-inflammatory IL-10 production. Mechanistically, EPI inhibited the TLR4 expression and phosphorylation of NF-κB p65 and MAPKs (JNK and ERK1/2) induced by LPS, but no changes were observed in TREM2 receptor expression in LPS-stimulated cells. In conclusion, our data demonstrated the potent anti-inflammatory properties of EPI in microglial cells. These effects are associated with the reduction of TLR4 expression and inhibition of intracellular signaling cascades, including NF-κB and MAPKs (JNK and ERK1/2).

Thymol reverses depression-like behaviour and upregulates hippocampal BDNF levels in chronic corticosterone-induced depression model in female mice.

OBJECTIVES: Based on this, the central therapeutic effects of thymol were verified in the neurotrophic pathway. METHODS: Female swiss mice were divided into four groups: control, corticosterone (Cort), thymol (Cort + thymol) and fluvoxamine (Cort + Flu). The administration of corticosterone was used to induce depressive symptoms for 23 days. After the treatment, the animals were exposed the behavioural tests, such as forced swimming test, tail suspension test, sucrose preference test, light/dark test, social interaction test, Y-maze test, plus-maze test and hole-board test. The hippocampus was also removed, and BDNF was measured by ELISA and Western blot. KEY FINDINGS: As a result, thymol and fluvoxamine were able to reverse the depressive symptoms, as well as to improve the anxious frame. The anhedonic and short-term memory was restored with the treatment. In the neurochemical tests, both thymol and fluvoxamine restored BDNF levels, improving the depressive condition. CONCLUSIONS: This work opens up new investigations aiming at the use of this molecule as a therapeutic alternative for treating depression disorders.

Involvement of the dopaminergic system in the antidepressant-like effect of the lectin isolated from the red marine alga Solieria filiformis in mice.

This study aimed at evaluating the antidepressant-like action of the marine alga Solieria filiformis lectin (SfL) and to investigate the participation of the monoaminergic system in this action. For this, male Swiss mice (n=10) were pretreated with intravenous injections (i.v.) of SfL (1, 3 or 9mg/kg) and submitted to open field (OFT), tail suspension (TST), forced swimming (FST), elevated plus-maze (EPMT) and hole-board tests (HBT). As controls, mice received sterile saline (i.v.), imipramine (10 or 30mg/kg; intraperitoneally - i.p.) or diazepam (1 mk/kg; i.p.). To assess the involvement of the monoaminergic system in SfL effects, the FST was conducted in mice pretreated with PCPA, an inhibitor of serotonin synthesis, or noradrenergic and dopaminergic receptors specific antagonists. The results showed that SfL has an antidepressant-like effect, with no psychostimulant and anxiolytic-like effects. When denatured or combined with mannan, SfL lost the ability to reduce the immobility time in the FST. In addition, SfL antidepressant-like effect was inhibited by the pretreatment of mice with SCH 23390, a dopamine D1 receptor antagonist, and by sulpiride, a dopamine D2 receptor antagonist. Thus, SfL produced an antidepressant-like effect, which is probably dependent on its interaction with the dopaminergic system.

Impact of the Chronic Omega-3 Fatty Acids Supplementation in Hemiparkinsonism Model Induced by 6-Hydroxydopamine in Rats.

Parkinson's disease (PD) is characterized by a progressive degeneration of dopaminergic neurons in the substantia nigra. The neuronal degeneration may result from the convergence of a number of different pathogenic factors, including apoptosis, excitotoxicity and oxidative stress. Many studies emphasize the importance of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in vital processes such as maintenance of the properties of cell membranes and the participation in signal transduction and biodynamic activity of neuronal membranes. In this study, the protective effect of ω-3 PUFA administration on the 6-hydroxydopamine (6-OHDA) model of PD in rats was investigated. ω-3 PUFA (1.5 and 3.0 g/kg) was orally administered by gavage during 28 consecutive days to male Wistar rats. On the 4th day, hemiparkinsonism was induced through intrastriatal injection of 6-OHDA. On the 25th day, the animals were submitted to behavioural analysis. On the 28th day, after euthanasia, the brain areas were collected for neurochemical evaluation. ω-3 PUFAs (1.5 and 3.0 g/kg) restored monoamine and amino acid levels on the striatum from hemiparkinsonian rats, followed by reduction in the number of apomorphine-induced rotations and promotion of a partial locomotor recovery. In addition, ω-3 PUFAs (1.5 and 3.0 g/kg) decreased the lipid peroxidation levels and nitrite levels in the brain areas from hemiparkinsonian rats. Thus, this study suggests that supplementation with ω-3 PUFAs prevents behavioural and neurochemical disturbances induced by 6-OHDA, presenting a potential neuroprotective action.

Antinociceptive and Anti-Inflammatory Effects of Ketamine and the Relationship to Its Antidepressant Action and GSK3 Inhibition.

Ketamine (KET), a NMDA antagonist, exerts an antidepressant effect at subanaesthetic doses and possesses analgesic and anti-inflammatory activities. We evaluated the involvement of KET antinociceptive and anti-inflammatory effects with its antidepressant action. Male Swiss mice were subjected to formalin, carrageenan-induced paw oedema and forced swimming tests, for assessing antinociceptive, anti-inflammatory and antidepressant effects. The treatment groups were as follows: control, KET (2, 5 and 10 mg/kg), lithium (LI: 5 mg/kg) and KET2 + LI5 combination. Immunohistochemistry analyses (TNF-α, iNOS, COX-2 and GSK3) in oedematous paws were performed. KET5 and KET10 reduced licking times in neurogenic (22 and 38%) and inflammatory (67 and 78%) phases of the formalin test, respectively, as related to controls. While LI5 inhibited the second phase by 24%, the licking time was inhibited by 26 and 59% in the KET2 + LI5 group (first and second phases). Furthermore, oedema volumes were reduced by 37 and 45% in the KET5 and KET10 groups, respectively. Oedema reductions were 29% in the LI5 group and 48% in the KET2 + LI5 group. In the forced swimming test, there were 23, 38 and 53% decreases in the immobility time in KET2, KET5 and KET10 groups, respectively. While LI5 caused no significant effect, decreases of 52% were observed with KET2 + LI5. KET also decreased TNF-α, iNOS, COX-2 and GSK3 immunostainings in oedematous paws, effects intensified with KET2 + LI5. We showed that KET presents antinociceptive and anti-inflammatory effects associated with its antidepressant response. Furthermore, our results indicate the close involvement of GSK3 inhibition and blockade of inflammatory responses, in the antidepressant drug effect.

Antinociceptive activity of carvacrol (5-isopropyl-2-methylphenol) in mice.

OBJECTIVES: Carvacrol (5-isopropyl-2-methylphenol) is a monoterpenic phenol which is present in the essential oil of oregano and thyme. We have investigated the behavioural effects of carvacrol in animal models of pain, such as acetic acid-induced abdominal constriction, formalin and hot-plate tests in mice. The spontaneous motor activity of animals treated with carvacrol was investigated using open-field and rotarod tests. METHODS: Carvacrol was administered orally, at single doses of 50 and 100 mg/kg while indometacin (5 mg/kg), morphine (7.5 mg/kg) and diazepam (2 mg/kg) were used as standard drugs. Naloxone (1 mg/kg) and l-arginine (150 mg/kg) were used to elucidate the possible antinociceptive mechanism of carvacrol on acetic acid-induced abdominal constriction and formalin tests. KEY FINDINGS: The results showed that carvacrol produced significant inhibitions on nociception in the acetic acid-induced abdominal constriction, formalin and hot-plate tests. In the open-field and rotarod tests carvacrol did not significantly impair the motor performance. The effect of the highest dose of carvacrol in mice in the acetic acid-induced abdominal constriction and formalin tests were not reversed by naloxone or l-arginine. CONCLUSIONS: Based on these results, it has been suggested that carvacrol presents antinociceptive activity that may not act through the opioid system nor through inhibition of the nitric oxide pathway.

Reversal of cocaine withdrawal-induced anxiety by ondansetron, buspirone and propranolol.

Cocaine is used worldwide and considered a public health problem. Relapse from addiction is one of the difficulties faced by cocaine users, and in most cases according to the period of abstinence, users may present symptoms such as anxiety or depression. To evaluate the anxiety-like behavior induced by different periods, rats were treated for 7 days with cocaine 20 mg/kg, i.p., and 24 h, 7 and 21 days after drug withdrawal were submitted to the elevated plus maze (EPM) and the open field (OF) tests. In different protocol, propranolol (10 mg/kg, i.p.), ondansetron (4 mg/kg, i.p.) and buspirone (5 mg/kg, i.p.) were administered once after 24 h and 7 days of abstinence from cocaine to evaluate possible reversal or attenuation of the symptoms caused by cocaine withdrawal. EPM results showed a reduction in all parameters after 24 h and 7 days of the last exposure to cocaine, indicating anxiety-like behavior. In the OF test, 24 h and 7 days of abstinence showed increased locomotor activity, while in the withdrawal 21 days the animals not alter the locomotor activity. The administration of propranolol, ondansetron or buspirone after a 24 h abstinence period reduced the animals anxiety in the EPM, and in the OF all drugs were able to reduce locomotor activity. After abstinence 7 d, the drugs reduced locomotor activity in the OF, in the EMP propranolol and ondansetron reversed the anxiogenic effect induced by cocaine. These results suggest that the treatment of anxyogenic effects of abstinence from cocaine is dependent on the period of the withdrawal.

Antidepressant-like effect of carvacrol (5-Isopropyl-2-methylphenol) in mice: involvement of dopaminergic system.

UNLABELLED: Carvacrol (5-isopropyl-2-methylphenol) is a monoterpenic phenol present in the essential oil of many plants. It is the major component of the essential oil fraction of oregano and thyme. In this study, the effect of carvacrol was investigated in two behavioral models, the forced swimming and tail suspension tests in mice, to investigate the possible antidepressant effect of this substance. Additionally, the mechanisms involved in the antidepressant-like effect of carvacrol in mice were also assessed. Carvacrol (cvc) was administered orally at single doses of 12.5, 25 and 50 mg/kg. The acute treatment of cvc decreased the immobility time in the forced swimming and tail suspension tests without accompanying changes in ambulation in the open-field test. The anti-immobility effect of carvacrol (25 mg/kg) was not prevented by pretreatment of mice with p-chlorophenylalanine, prazosin and yohimbine. On the other hand, the pretreatment of mice with SCH23390 or sulpiride completely blocked the antidepressant-like effect of carvacrol (25 mg/kg) in the forced swimming test. These results show that carvacrol presents antidepressant effects in the forced swimming and tail suspension tests; this effect seems to be dependent on its interaction with the dopaminergic system, but not with the serotonergic and noradrenergic systems. KEYWORDS: Carvacrol; Antidepressant; Forced swimming; Tail suspension; Dopaminergic system.

Anxiolytic-like effect of the monoterpene 1,4-cineole in mice.

Recent studies have shown that some monoterpenes exert anxiolytic- and depressant-like actions, however, these effects from monoterpene 1,4-cineole are still unknown. This work aimed to study the effects of 1,4-cineole in classic animal models for depression- and anxiety-like behavior, specifically the elevated plus maze (EPM), hole board, open field, pentobarbital sleeping time, forced swimming, tail suspension and rota rod tests. 1,4-Cineole was administered orally to mice (100, 200 and 400 mg/kg), while diazepam (1 or 2 mg/kg) and imipramine (10 or 30 mg/kg) were used as standard drugs. 1,4-Cineole (400 mg/kg) modified all parameters observed in the EPM, while no significant variation was observed on general motor activity in the open-field test. In the hole-board assay, 1,4-cineole induced increase on the number of head dips. Forced swimming and tail suspension tests showed that cineole (200 and/or 400 mg/kg) was able to promote significant increase on the immobility time, while a decreased sleep latency was observed (200 and 400 mg/kg ) on the pentobarbital sleeping time. Cineole had no effect on the motor coordination of animals in the rota rod test. The results suggest that 1,4-cineole presents potential anxiolytic-like action consistent with possible general depression of the CNS.

Behavioral alterations and pro-oxidant effect of a single ketamine administration to mice.

A growing body of evidence has pointed to the ionotropic glutamate N-methyl-d-aspartate receptor (NMDA) as an important player in the etiology of psychopathologies, including anxiety and major depression. Clinical findings suggest that ketamine may be used for the treatment of major depression. There is evidence that reactive oxygen species also play an important role in the pathogenesis of many diseases, particularly those which are neurological and psychiatric in nature. This study examined the behavioral and oxidative stress alterations after a single administration of ketamine (5, 10 and 20mg/kg i.p.) in mice. Ketamine presented a significant anxiogenic effect in the elevated plus-maze model of anxiety, also increasing locomotor activity. In the forced swimming and tail suspension tests, a significant decrease in immobility time after ketamine administration was observed. In addition to the behavioral changes induced by ketamine, this drug also increased lipid peroxidation, nitrite content and catalase activity, while decreased GSH levels in mice prefrontal cortex. In conclusion, our results confirm the antidepressant effects of ketamine, also showing a pro-oxidant effect of this drug.

Anxiolytic-like effect of Carvacrol (5-isopropyl-2-methylphenol) in mice: involvement with GABAergic transmission.

Carvacrol (5-isopropyl-2-methylphenol) is a monoterpenic phenol present in the essencial oil of many plants. It is the major component of the essential oil fraction of oregano and thyme. This work presents the behavioral effects of carvacrol in animal models of elevated plus maze (EPM), open field, Rotarod and barbiturate-induced sleeping time tests in mice. Carvacrol (CVC) was administered orally, in male mice, at single doses of 12.5; 25 and 50 mg/kg while diazepam 1 or 2 mg/kg was used as standard drug and flumazenil (2.5 mg/kg) was used to elucidate the possible anxiolytic mechanism of CVC on the plus maze test. The results showed that CVC, at three doses, had no effect on the spontaneous motor activity in the Rotarod test nor in the number of squares crossed in the open-field test. However, CVC decreased the number of groomings in the open-field test. In the plus maze test, CVC, at three doses significantly increased all the observed parameters in the EPM test and flumazenil was able to reverse the effects of diazepam and CVC. Therefore, CVC did not alter the sleep latency and sleeping time in the barbiturate-induced sleeping time test. These results show that CVC presents anxiolytic effects in the plus maze test which are not influenced by the locomotor activity in the open-field test.

Evaluation of effects of N-(2-hydroxybenzoyl) tyramine (riparin II) from Aniba riparia (NEES) MEZ (Lauracea) in anxiety models in mice.

In order to evaluate the effects produced by N-(2-hydroxybenzoyl) tyramine (riparin II) isolated from the unripe fruit of Aniba riparia (NEES) MEZ (Lauraceae) on the central nervous system, different behavioral tests were performed. Riparin II (rip II) was administered orally (p.o.) and intraperitoneally (i.p.) in male mice, at doses of 25, 50 and 75 mg/kg, and tested on elevated plus maze (EPM), open field, rota rod and hole board tests. The results revealed that rip II caused considered increase of the number of head dips in hole board test and increased the number of entries and the time of permanence in the open arms in plus maze test in both routes. No significant effect was evidenced on rota rod and open field test, except an increase observed in the number of rearing. These results showed that riparin II presents anxiolytic-like effects in the plus maze and hole board tests which are not influenced by the locomotor activity as detected in the open field test.

Antinociceptive effect of the monoterpene R-(+)-limonene in mice.

In the present study were studied the antinociceptives properties of monoterpene R-(+)-limonene (LM) in chemical and thermal models of nociception in mice. The R-(+)-limonene was administered, intraperitoneally (i.p.), at doses of 25 and 50 mg/kg. The results showed significant inhibition produced on chemical nociception induced by intraperitoneal acetic-acid and in the second phase of subplantar formalin test, but did not manifest a significant effect in hot-plate test. The R-(+)-limonene-induced antinociception in second phase of formalin test was insensitive to naloxone (1 mg/kg, s.c.). It was also demonstrated that R-(+)-limonene (25, 50 mg/kg) neither significantly enhanced the pentobarbital-sleeping time nor impaired the motor performance in rota-rod test, indicating that the observed antinociception is unlikely to be due to sedation or motor abnormality. In conclusion it may be suggested that the R-(+)-limonene presented antinociceptive activity and that, probably, this action can be related with peripheral analgesia, but, not with the stimulation of opioids receptors.

Anxiolytic-like effects of (O-methyl)-N-2,6-dihydroxybenzoyl-tyramine (riparin III) from Aniba riparia (Nees) Mez (Lauraceae) in mice.

This work presents behavioral effects of (O-methyl)-N-2,6-dihydroxybenzoyl-tyramine (riparin III) isolated from the unripe fruit of Aniba riparia (Nees) Mez (Lauraceae) in animal models of open field, rota rod, elevated plus maze and hole board tests in mice. Riparin III (ripIII) was administered orally, in male mice, at single doses of 25 and 50 mg/kg. The results showed that ripIII, at both doses, had no effects on the spontaneous motor activity in the rota rod test nor in the number of squares crossed in the open field test. However, riparin III decreased the number of grooming and rearing. In the plus maze test, ripIII, at both doses increased the following parameters: percentage of entries in the open arms (PEOA), time of permanence in the open arms (TPOA) and percentage of time of permanence in the open arms (PTOA) and at the dose of 50 mg/kg, increased the number of entries in the open arms (NEOA). Similarly, ripIII, at both doses, showed an increase in the number of head dips into the holes of the hole board test. These results show that riparin III presents anxiolytic effects in the plus maze and hole board tests which are not influenced by the locomotor activity in the open field test.

Cocaine alters catalase activity in prefrontal cortex and striatum of mice.

Catalase is one of the enzymes that convert hydrogen peroxide (H2O2) to H2O presenting a protective role against free radicals. In this study, catalase activity was determined in homogenates of striatum (ST) and prefrontal cortex (PFC) in order to examine the participation of oxidative stress (OS) on cocaine actions in mice brain. Male Swiss mice were injected (i.p.) with cocaine at low (10 and 30 mg/kg) and high doses (90 mg/kg), and observed for 1 h. After cocaine overdose (90 mg/kg) some animals presented only status epilepticus (SE) while others died after seizures. These animals were dissected and divided in two groups, SE and death. Catalase activity was also determined after pretreatment with the anticonvulsant drug, diazepam, alone or injected before cocaine 90 mg/kg, and after seizures induced by a high dose of bupropion, a known inhibitor of NE and DA reuptake used for comparison. Results showed a decrease in catalase activity of the PFC and ST after SE and death induced by cocaine and bupropion overdoses. Cocaine at low doses decreased the enzyme activity only in ST. Diazepam treatment alone and before cocaine overdose did not interfere with catalase activity. This reduction in catalase activity may reflect an increase in H2O2 content in PFC and ST. Previous data reports that H2O2 inhibits dopamine transporter activity, suggesting that the decrease in catalase activity may potentiate the toxic mechanism of drugs that inhibit monoamines reuptake. As far as we know, this is the first report showing an involvement of OS in the cocaine's central mechanism of action.