L.K.S. Kanazawa

Antinociceptive and anti-inflammatory potential of extract and isolated compounds from the leaves of Salvia officinalis in mice

ETHNOPHARMACOLOGICAL RELEVANCE Salvia officinalis L. has been used as a traditional herbal medicine for gastric disturbances and inflammatory processes. This study investigated the toxicological, antinociceptive and anti-inflammatory effects of the hydroalcoholic extract (HE) from leaves of Salvia officinalis and its isolated compounds in mice. MATERIALS AND METHODS Mice were treated with HE before the induction of nociceptive response by chemical agents (acetic-acid, formalin, glutamate, capsaicin and cinnamaldehyde). Total leukocytes and plasma extravasation induced by acetic acid and paw oedema induced by glutamate, capsaicin and cinnamaldehyde were also measured. The antinociceptive effect of carnosol and ursolic acid/oleanolic acid were evaluated on formalin and cinnamaldehyde models. RESULTS In the acute toxicity test the value of estimated LD50 for HE was 44.7579 g/kg. Oral administration of HE (10, 30 and 100 mg/kg) inhibited the number of writhings, total leukocytes and plasma extravasation induced by acetic acid. In the formalin test, HE reduced both neurogenic and inflammatory phases, effect that was affected by naloxone. The glutamate-, capsaicin- and cinnamaldehyde-induced nociception and paw oedema were reduced by HE at doses that did not affect the locomotor activity of mice in the open field test. Carnosol (10mg/kg) and ursolic acid/oleanolic acid (30 mg/kg) inhibited the inflammatory phase of formalin and the nociception and mechanical allodynia induced by cinnamaldehyde. CONCLUSIONS These results demonstrate that HE presents significant anti-inflammatory and also antinociceptive effects on chemical behavioral models of nociception that involves an opioid mechanism. In addition, carnosol and ursolic acid/oleanolic acid contained in this plant appears to contribute for the antinociceptive property of the extract, possibly through a modulatory influence on TRPA1-receptors. However, further studies regarding the precise site and the mechanism of action of HE and carnosol and ursolic acid/oleanolic acid merited exploring further.

Quercetin reduces manic-like behavior and brain oxidative stress induced by paradoxical sleep deprivation in mice

Quercetin is a known antioxidant and protein kinase C (PKC) inhibitor. Previous studies have shown that mania involves oxidative stress and an increase in PKC activity. We hypothesized that quercetin affects manic symptoms. In the present study, manic-like behavior (hyperlocomotion) and oxidative stress were induced by 24h paradoxical sleep deprivation (PSD) in male Swiss mice. Both 10 and 40mg/kg quercetin prevented PSD-induced hyperlocomotion. Quercetin reversed the PSD-induced decrease in glutathione (GSH) levels in the prefrontal cortex (PFC) and striatum. Quercetin also reversed the PSD-induced increase in lipid peroxidation (LPO) in the PFC, hippocampus, and striatum. Pearsons correlation analysis revealed a negative correlation between locomotor activity and GSH in the PFC in sleep-deprived mice and a positive correlation between locomotor activity and LPO in the PFC and striatum in sleep-deprived mice. These results suggest that quercetin exerts an antimanic-like effect at doses that do not impair spontaneous locomotor activity, and the antioxidant action of quercetin might contribute to its antimanic-like effects.

Evaluation of 50-kHz ultrasonic vocalizations in animal models of mania: Ketamine and lisdexamfetamine-induced hyperlocomotion in rats

Drug-induced hyperlocomotion in rodents is frequently used as a behavioral model for mania. However, the use of locomotor activity as the single parameter in these animal models of mania may pose some limitations for developing new pharmacological treatments. Thus, alternative behavioral markers are required. Fifty-kHz ultrasonic vocalizations (USV), which are thought to represent positive affect, are increased by the administration of the psychostimulant d-amphetamine, an effect that can be prevented by lithium treatment, the gold standard antimanic drug for treating bipolar disorder. The aim of this study was to evaluate 50-kHz USV in two other pharmacological-induced animal models of mania: ketamine (KET)- and lisdexamfetamine (LDX)-induced hyperlocomotion. After systemic injection of LDX (10mg/kg, ip), racemic-ketamine (25mg/kg, ip) or S-ketamine (25mg/kg, ip), locomotor activity and 50-kHz USV emission were evaluated in rats. Furthermore, the effects of an antimanic treatment, namely lithium carbonate (100mg/kg, ip), on LDX-induced 50-kHz USV and hyperlocomotion were tested. Rats treated with racemic KET and S-KET showed increased locomotor activity, but these drug treatments did not significantly affect 50-kHz USV emission rates. On the other hand, LDX administration increased both locomotor activity and 50-kHz USV with both effects being reversed by lithium administration. The present findings suggest that 50-kHz USV can differentiate between drug-induced models of mania, which may represent different types of manic episodes. Thus, measuring 50-kHz USV might serve as an additional valuable behavioral variable to assess mania-like phenotypes in rat models.

Effects of acute and chronic quercetin administration on methylphenidate-induced hyperlocomotion and oxidative stress.

Aims: Increases in protein kinase C (PKC) and oxidative stress have been related to mania. Drugs with antioxidant effects or inhibitory actions on PKC may have antimanic effects. The flavonoid quercetin has antioxidant and PKC‐inhibiting effects that resemble those of lithium, the first‐line treatment for mania in bipolar disorder. We hypothesized that quercetin may have antimanic‐like effects in an animal model. Main methods: In the present study, we investigated the effects of acute and chronic treatment with quercetin (2.5, 5, 10, and 40 mg/kg, i.p.) in male Swiss mice that were subjected to methylphenidate (5 mg/kg, i.p.)‐induced hyperlocomotion, an animal model of mania. Lithium (100 mg/kg, i.p.) and diazepam (5 mg/kg, i.p.) were used as positive and negative controls, respectively. We also evaluated the effects of these treatments on methylphenidate‐induced oxidative stress in the brain by measuring reduced glutathione (GSH) and lipid peroxidation (LPO) levels in the prefrontal cortex, hippocampus, and striatum. Key findings: Acute and chronic (21‐day) treatment with lithium and diazepam reduced methylphenidate‐induced hyperlocomotion. Chronic but not acute treatment with quercetin (10 and 40 mg/kg) blocked methylphenidate‐induced hyperlocomotion. These effects of lithium and quercetin occurred at doses that did not alter spontaneous locomotor activity, whereas diazepam reduced spontaneous locomotor activity. Chronic treatment with lithium and quercetin blocked the methylphenidate‐induced increase in LPO levels in the striatum. Significance: These results suggest that chronic quercetin treatment has antimanic‐like and antioxidant effects, thus encouraging further studies of quercetin as a putative new antimanic drug.

Social interaction with rat exposed to constant light during lactation prevents depressive-like behavior induced by constant light in adulthood

Circadian rhythm disruptions are often observed in depressed patients, and changes in the light/dark cycle promote depressive-like behavior in animal models. Prolonged exposure to constant light (LL) is known to lead to arrhythmicity of circadian locomotor activity and depressive-like behavior in rats. Interestingly, neonatal exposure to LL prevents both arrhythmicity and depressive behavior in adulthood. Arrhythmic rats under LL conditions that cohabitate with a rhythmic rat exhibit improvement in circadian rhythms. We tested whether such cohabitation also protects against LL-induced depressive-like behavior. Wistar rats were assigned to conditions of either neonatal constant light (neonatal-LL) on postnatal days 10-22 or a regular light/dark cycle (neonatal-LD). On day 45, the animals were assigned to three possible pair combinations. After a baseline sucrose preference test, half of the pairs were placed under LL conditions. Weekly sucrose preference tests were conducted to evaluate depressive-like behavior. The animals were isolated by an aluminum wall on the test day. At week 2 of LL, sucrose preference was reduced in neonatal-LD/neonatal-LD pairs of animals. At week 5, neonatal-LD/neonatal-LD pairs exhibited anhedonic-like behavior, but the pairs with at least one neonatal-LL rat did not. The LL cycle was returned to an LD cycle, and the neonatal-LD/neonatal-LD pairs exhibited a restoration of sucrose preference 2 weeks later. We conclude that social interaction can prevent depressive-like behavior induced by circadian rhythm disruption as long as one of the animals is more prone to present a strong rhythm.

Effects of ketamine on vocal impairment, gait changes, and anhedonia induced by bilateral 6-OHDA infusion into the substantia nigra pars compacta in rats: Therapeutic implications for Parkinson’s disease

GRAPHICAL ABSTRACT Figure. No caption available. &NA; Parkinsons disease is a chronic neurodegenerative disorder characterized by cardinal motor features, such as bradykinesia, but also vocal deficits (e.g. difficulties to articulate words and to keep the tone of voice) and depression. In the present study, rats with bilateral 6‐hydroxydopamine lesion of the substantia nigra pars compacta were evaluated for changes in the emission of 50‐kHz ultrasonic vocalizations, gait impairment (catwalk test), and depressive‐like behaviour (sucrose preference test). Furthermore, we evaluated the effect of repeated treatment (28 days) with ketamine (5, 10, and 15 mg/kg, ip, once per week) or imipramine (15 mg/kg, ip, daily). The lesion had prominent effects on the production of 50‐kHz ultrasonic vocalizations (reduced call numbers, call durations, total calling time, and increased latency to start calling), led to gait impairment (increased run duration and stand of right forelimb) and induced anhedonia (reduced sucrose preference). Also, significant correlations between gait changes, sucrose preference, and ultrasonic calling were found, yet, except for run duration and sucrose preference, these correlations were low indicating that these associations are weak. Importantly, ketamine and imipramine reversed lesion‐induced anhedonia and improved gait impairments, but neither drug improved ultrasonic calling. In conclusion, the substantia nigra lesion with 6‐hydroxydopamine induced subtle motor and non‐motor manifestations, reflecting key features of the wide clinical spectrum of early Parkinsons disease. Furthermore, the present results suggest a potential efficacy of ketamine on depression and gait alterations in Parkinsons disease.

Anti-fatigue activity of an arabinan-rich pectin from acerola (Malpighia emarginata)

A fraction composed of an arabinan-rich pectin was extracted from acerola fruit (Malpighia emarginata) and named ACWS. This fraction presented 93% of total carbohydrate, relative molecular weight of 7.5×104g/mol, galacturonic acid, arabinose, galactose, xylose and rhamnose in 52.1:32.4:7.2:4.8:3.5 molar ratio and had its structure confirmed by NMR analysis. The anti-fatigue activity of ACWS was evaluated using the weight load swim test on trained mice. ACWS was orally administered at doses of 50mg/kg, 100mg/kg and 200mg/kg for 28days. Plasma biochemical parameters, respiration of permeabilized skeletal muscle fibers, and GSH levels and lipoperoxidation in the brain (pre-frontal cortex, hippocampus, striatum and hypothalamus) were determined. ACWS could lengthen the swimming time, increase the plasma levels of glucose, triglycerides, lactate, and the GSH levels in the hippocampus at all tested doses. The mitochondrial respiratory capacity of the skeletal muscle was increased at middle and high ACWS doses. This study provides strong evidence that M. emarginata pectic polysaccharide supplementation has anti-fatigue activity, can modify the kinetics of energy substrates (carbohydrate and fat) mobilization and the respiratory capacity of the skeletal muscle, as well the antioxidant status in the hippocampus of ACWS treated animals.