Tail Suspension Test In Mice Research Articles

Potential of novel phytoecdysteroids isolated from Vitex doniana in the treatment depression: Involvement of monoaminergic systems

Vitex doniana Sweet (Verbanaceae) is used in traditional African medicine for the treatment of neurological disorders including depression. In our previous studies, three new phytoecdysteroids were isolated from methanol stem bark extract of V. doniana (VD) (11β-hydroxy-20-deoxyshidasterone, 21-hydroxyshidasterone, and 2,3-acetonide-24-hydroxyecdysone) along with known ecdysteroids. This study was designed to investigate antidepressant-like effect of VD and the isolated phytoecdysteroids in behavioral models of despair, forced-swim test (FST) and tail-suspension test (TST) in mice. VD (100 and 200mg/kg, p.o.) treatment reduced (P<0.05) the duration of immobility in both tests without affecting the locomotor activity and exploratory behavior as observed in the open field test. Similarly, 21-hydroxyshidasterone, 11β-hydroxy-20-deoxyshidasterone, ajugasterone and 24-hydroxyecdysone acute oral treatments significantly reduced immobility time with peak effect at 10mg/kg, which was similar to the effect of conventional antidepressants (imipramine and fluoxetine) in the FST. Conversely, pretreatment of mice with yohimbine (1mg/kg, i.p., α2-adrenoceptor antagonist), ketanserin (5mg/kg, i.p., 5-HT2A/2C receptor antagonist) or sulpiride (dopamine D2 receptor antagonist) prevented the antidepressant-like effect of 21-hydroxyshidasterone while the effects of 11β-hydroxy-20-deoxyshidasterone and 24-hydroxyecdysone were blocked by yohimbine or ketanserin in the FST. Moreover, the anti-immobility effect elicited by ajugasterone was prevented by prazosin (62.5μg/kg, i.p., α1-adrenoceptor antagonist) pretreatment. Our findings demonstrated that V. doniana and its phytoecdysteroids constituents elicited antidepressant-like effect in behavioral paradigm of despair. Furthermore, 21-hydroxyshidasterone produces its antidepressant-like effect through interaction with α2-adrenoceptor, 5-HT2A/2C receptor and dopamine D2-receptors but 11β-hydroxy-20-deoxyshidasterone and 24-hydroxyecdysone effects depend on interaction with α2-adrenoceptor and 5-HT2A/2C receptors while ajugasterone produces its action through interaction with post-synaptic α1-adrenoceptors. Thus, phytoecdysteroids could play a pivotal role in the treatment of major depression.

Enhanced antidepressant-like effects of the macromolecule trefoil factor 3 by loading into negatively charged liposomes

Enhanced antidepressant-like effects of the macromolecule trefoil factor 3 by loading into negatively charged liposomes Jing Qin,1 Xu Yang,1&ndash;3&nbsp;Jia Mi,4 Jianxin Wang,1 Jia Hou,1,2 Teng Shen,1 Yongji Li,2 Bin Wang,4 Xuri Li,4 Weili Zhu5 1Department of Pharmaceutics, School of Pharmacy, Fudan University, Key Laboratory of Smart Drug Delivery, Ministry of Education, Shanghai, 2Department of Pharmaceutics, School of Pharmacy, Heilongjiang University of Chinese Medicine, Harbin, 3Department of Pharmacy, The&nbsp;Fifth People&rsquo;s Hospital of Shanghai, Fudan University, Shanghai, 4Binzhou Medical University, Yantai, 5National Institute on Drug Dependence, Peking University, Beijing, People&rsquo;s Republic of China Abstract: Immunocytes, mainly neutrophils and monocytes, exhibit an intrinsic homing property, enabling them to migrate to sites of injury and inflammation. They can thus act as Trojan horses carrying concealed drug cargoes while migrating across impermeable barriers to sites of disease, especially the blood&ndash;brain barrier (BBB). In this study, to target circulating phagocytic cells, we formulated negatively charged nanosize liposomes and loaded trefoil factor 3 (TFF3) into liposomes by the pH-gradient method. According to the optimized formulation (5:1.5&nbsp;of lipid to cholesterol, 10:1 of lipid to drug, 10 mg/mL of lipid concentration, and 10&nbsp;mmol/L of phosphate-buffered saline), 44.47% entrapment efficiency was obtained for TFF3 liposomes with 129.6 nm particle size and &ndash;36.6 mV zeta potential. Compared with neutrally charged liposomes, the negatively charged liposomes showed a strong binding capacity with monocytes and were effectively carried by monocytes to cross the BBB in vitro. Furthermore, enhanced antidepressant-like effects were found in the tail-suspension and forced-swim tests in mice, as measured by decreased immobility time, as well as increased swimming time and reduced immobility in rats. These results suggested that negatively charged liposomes could improve the behavioral responses of TFF3, and our study opens up a new way for the development of effective therapies for brain disease by increasing the permeability of the BBB. Keywords: TFF3, drug delivery system, monocytes, brain-targeting drug delivery, antidepressant, blood&ndash;brain barrier

In vitro and in vivo characterization of PA01, a novel promising triple reuptake inhibitor

Triple reuptake inhibitors (TRIs) that inhibit the reuptake of serotonin (5-HT), norepinephrine (NE), and dopamine (DA) are being developed as a new class of antidepressants, which is hypothesized to produce more rapid onset and better efficacy than conventional antidepressants in part due to the addition of the DA component. 4-[2-(dimethylamino)-1-(1-hydroxycyclohexyl)-ethyl]-phenyl benzoate hydrochloride (PA01), a novel compound, potently bound to the human 5-HT, NE, and DA transporters (Ki=105, 644, and 813nM, respectively), and inhibited the reuptake of 5-HT, NE, and DA into recombinant cells (IC50=341, 427, and 753nM, respectively). In vivo, PA01 dose-dependently decreased immobility time in the forced swimming test (FST) in rats, and the tail suspension test (TST) in mice with higher efficacy than desvenlafaxine succinate (DVS), and showed no stimulatory effect on the spontaneous locomotor activity. The anti-immobility effect of PA01 in the TST was significantly prevented by the pretreatment of mice with DL-p-chlorophenylalanine (pCPA, 300mg/kg, an inhibitor of serotonin synthesis), SCH23390 (0.05mg/kg, s.c., dopamine D1 receptor antagonist), and sulpiride (50mg/kg, i.p., dopamine D2 receptor antagonist). PA01 significantly increased head-twitch response induced by 5-hydroxytryptophan (80mg/kg, i.p., a metabolic precursor to serotonin) in rats, potentiated yohimbine (25mg/kg, s.c., a α2-adrenoceptor antagonist) toxicity, and antagonized high dose apomorphine-induced hypothermia in mice. Taken together, these in vitro and in vivo results indicated that PA01 is a novel triple reuptake inhibitor, and exerts an excellent antidepressant activity in the behavioral despair animal models of depression, with more potent antidepressant activity than DVS at the same dose.

Evaluation of phytoconstituents and assessment of adaptogenic activity in vivo in various extracts of Rhododendron arboreum (leaves)

Natural products particularly of plant origin with antistress property and nutraceutical value have become the focus of scores of scientific investigation in recent times. Against this background the present study was carried out to analyse the phytochemical components and adaptogenic activity of Rhododendron arboreum which grow in high altitudes. Adaptogenic activity of the plant extract was evaluated in vivo in rat and mice animal models. Methanol, hydroethanol and aqueous extract of the leaves were prepared and preliminary screening of the phytochemical constiteunts was carried out. The important phytoconstituents viz. flavonoids and phenolics were estimated and amount of gallic acid and quercetin were evaluated by HPTLC. Adaptogenic activity of the extract was studied in vivo using rat and mice as test animals. The criteria taken were forced swimming test in rat and mice and tail suspension test in mice. Methanol extract showed the presence of diterpenes, triterpenes, flavonoids, steroids, tannin, phenolics. Hydroethanol extract showed the presence of diterpenes, triterpenes, saponin, glycosides, alkaloids, tannin and aqueous extract showed the presence of tannin, glycosides, triterpenes, flavonoids, diterpenes. Quantitative analysis exhibited that the methanol extract have the highest amount of flavonoid and phenolics. The HPTLC profile of methanol extract showed the presence of highest amount of quercetin. Gallic acid was detected only in methanol extract. In vivo study in test animals revealed that the methanol extract of R. arboreum exhibited potent anti stress activity. Hence, presence of these compounds which are known to have strong anti-oxidant activity in high quantity might be responsible for adaptogenic activity.

Design, synthesis, and pharmacological evaluation of novel 2-(4-substituted piperazin-1-yl)1, 8 naphthyridine 3-carboxylic acids as 5-HT3 receptor antagonists for the management of depression.

1, 8-naphthyridine-3-carboxylic acid analogs were synthesized and found to possess potential 5-HT3 receptor antagonism as well as antidepressant-like activity. Initially, 5-HT3 receptor antagonism of all the compounds was determined in the form of pA2 value against agonist 2-methyl 5-HT in longitudinal muscle-myenteric plexus preparation from guinea-pig ileum. Among all the compounds tested, compound 7a demonstrated most promising pA2 value of 7.6. Subsequently, all the compounds were evaluated for antidepressant activity using forced swim test and tail suspension test in mice. Compounds 7a, 7d, 7f, 7h, and 7i exhibited significant (p<0.05) antidepressant-like activity as compound to vehicle-treated group. Importantly, none of the tested compound affected locomotor activity of mice at tested dose levels.

Serotonergic and noradrenergic systems are implicated in the antidepressant-like effect of ursolic acid in mice

Ursolic acid (UA) is a natural pentacyclic triterpenoid carboxylic acid that exerts antidepressant-like effects in the tail suspension test (TST) and in the forced swimming test, and this effect was reported to be mediated by the dopaminergic system. Many studies show that currently available antidepressant agents have effects on multiple neurotransmitter systems which account for their efficacy. Therefore, this study was aimed at investigating the possible involvement of the serotonergic, noradrenergic, glutamatergic and opioid systems in the antidepressant-like effect of UA. To this end, several pharmacological agents were administered to verify their ability to influence the antidepressant-like responses elicited by UA in the TST in mice. The open-field test was used to assess the locomotor activity. The results show that the pre-treatment of mice with ρ-chlorophenylalanine (100mg/kg, i.p., 4days) or α-methyl-ρ-tyrosine (100mg/kg, i.p.) but not with N-methyl-d-aspartate (0.1pmol/mouse, i.c.v.) or naloxone (1mg/kg, i.p.), was able to prevent the antidepressant-like effect of UA (0.1mg/kg, p.o.). Sub-effective doses of fluoxetine (5mg/kg, p.o.) or reboxetine (2mg/kg, p.o.), but not ketamine (0.1mg/kg, i.p.) or MK-801 (0.001mg/kg, p.o.), was capable of potentiating the effect of a sub-effective dose of UA (0.001mg/kg, p.o.) in the TST. None of the treatments affected locomotor activity. Altogether, the results show an involvement of the serotonergic and noradrenergic systems, but not the glutamatergic or opioid systems, in the antidepressant-like effect of UA.

Phloroglucinol Derivatives Present an Antidepressant-like Effect in the Mice Tail Suspension Test (TST)

The antidepressant-like effects of phloroglucinol and seven synthetic related derivatives were investigated using the tail suspension test (TST) in mice. Compounds 2-methyl-1-[2,4,6-trihydroxy-3-(2-methylpropanoyl)phenyl] propan-l-one (5), 1-(2,4,6-trihydroxyphenyl)ethan-l-one (6), 1-(3-acetyl-2,4,6-trihydroxyphenyl)ethan-l-one (7), 2-methyl-1 -[2,4,6-trihydroxy-3-(2-methylpropanoyl)-5-{ [2,4,6-trihydroxy-3,5-bis(2-methylpropanoyl)phenyl]methyl phenyl] propan-1-one (9) and 1-{3-acetyl-5-[(3,5-diacetyl-2,4,6-trihydroxyphenyl)methyl]-2,4,6-trihydroxyphenyl}ethan-1-one (10), containing acyl groups, decreased the immobile behavior of mice treated orally with equimolar doses of imipramine 20 mg/kg, with no alterations in locomotor activity as assessed by the open-field test. These results suggest that these phloroglucinol derivatives could represent a new molecular model in the search for antidepressant drugs.

Alarin-induced antidepressant-like effects and their relationship with hypothalamus–pituitary–adrenal axis activity and brain derived neurotrophic factor levels in mice

Alarin is a newly identified member of the galanin family of peptides. Galanin has been shown to exert regulatory effects on depression. Similar to galanin in distribution, alarin is also expressed in the medial amygdala and hypothalamus, i.e., regions interrelated with depression. However, it remains a puzzle whether alarin is involved in depression. Accordingly, we established the depression-like mouse model using behavioral tests to ascertain the possible involvement of alarin, with fluoxetine as a positive control. With the positive antidepressant-like effects of alarin, we further examined its relationship to HPA axis activity and brain-derived neurotrophic factor (BDNF) levels in different brain areas in a chronic unpredictable mild stress (CUMS) paradigm. In the acute studies, alarin produced a dose-related reduction in the immobility duration in tail suspension test (TST) in mice. In the open-field test, intracerebroventricular (i.c.v.) injection of alarin (1.0nmol) did not impair locomotion or motor coordination in the treated mice. In the CUMS paradigm, alarin administration (1.0nmol, i.c.v.) significantly improved murine behaviors (FST and locomotor activity), which was associated with a decrease in corticotropin-releasing hormone (CRH) mRNA levels in the hypothalamus, as well as a decline in serum levels of CRH, adrenocorticotropic hormone (ACTH) and corticosterone (CORT), all of which are key hormones of the HPA axis. Furthermore, alarin upregulated BDNF mRNA levels in the prefrontal cortex and hippocampus. These findings suggest that alarin may potentiate the development of new antidepressants, which would be further secured with the identification of its receptor(s).

Hesperidin exerts antidepressant-like effects in acute and chronic treatments in mice: Possible role of l-arginine-NO-cGMP pathway and BDNF levels

Hesperidin (4'-methoxy-7-O-rutinosyl-3',5-dihydroxyflavanone), a naturally occurring flavanone glycoside, was previously shown to produce an antidepressant-like effect with modultation of the serotonergic 5-HT1A and kappa-opioid receptors. In this study, the signaling mechanisms underlying their antidepressant-like effects were further evaluated by investigating in acute and chronic treatments. Results showed that chronic treatment of hesperidin or hesperitin (0.1, 0.3 and 1mg/kg, intraperitoneal, i.p.) have an antidepressant-like effect in the mouse tail suspension test (TST) without modified the locomotor activity in the open field test. Pretreatment with l-arginine (a nitric oxide (NO) precursor), sildenafil (a phosphodiesterase 5 inhibitor) or S-nitroso-N-acetyl-penicillamine (a NO donor) significantly reversed the reduction in immobility time elicited by acute treatment with hesperidin (0.3mg/kg) in the TST. Hesperidin (0.01mg/kg, a sub-effective dose in acute treatment) produced an additive antidepressant-like effect with N(G)-nitro-l-arginine (an inhibitor of nitric oxide synthase (NOS)) or 7-nitroindazole (a neuronal NOS inhibitor) in the TST. Pretreatment of animals with methylene blue (an inhibitor of NOS/soluble guanylate cyclase (sGC)) or ODQ (a specific inhibitor sGS) caused an additive effect with hesperidin in the TST. Hesperidin in the acute (1mg/kg) and chronic (0.1, 0.3 and 1mg/kg) treatments caused a significant decrease in nitrate/nitrite (NOX) levels in the hippocampus of mice. Chronic treatment with hesperidin (0.3 and 1mg/kg) also resulted in an increase in hippocampal brain-derived neurotrophic factor (BDNF) levels. These results demonstrated that the antidepressant-like effect of hesperidin is likely mediated by inhibition of l-arginine-NO-cGMP pathway and by increased of the BDNF levels in hippocampus.

Involvement of PKA, PKC, CAMK-II and MEK1/2 in the acute antidepressant-like effect of creatine in mice

BackgroundThe aim of this study was to investigate the involvement of signaling pathways on the creatine antidepressant-like effect in the tail suspension test (TST) in mice. MethodsThe TST was used to assess the antidepressant-like properties of creatine. ResultsThe anti-immobility effect of creatine (1mg/kg, p.o.) in the TST was blocked by i.c.v. pretreatment with H-89 (1μg/site, PKA inhibitor), KN-62 (1μg/site, CAMK-II inhibitor), chelerythrine (1μg/site, PKC inhibitor), U0126 (5μg/site, MEK1/2 inhibitor) or PD09058 (5μg/site, MEK1/2 inhibitor). ConclusionThese results suggest that the antidepressant-like effect of creatine is dependent on PKA, CaMK-II, PKC and MEK 1/2 activation.

Antidepressant-like effects of auraptenol in mice

Depression is a major psychiatric disorder affecting nearly 21% of the world population and imposes a substantial health burden on society. Current available antidepressants are not adequate to meet the clinical needs. Here we report that auraptenol, an active component of the traditional Chinese medicine, angelicae dahuricae radix, had antidepressant-like effects in mice models of depression. In mouse forced swimming test and tail suspension test, two validated models of depression, auraptenol dose-dependently decreased the immobility duration within the dose range of 0.05–0.4 mg/kg. In addition, the antidepressant-like effects of auraptenol was significantly averted by a selective serotonin 5-HT1A receptor antagonist WAY100635 (1 mg/kg). These doses that affected the immobile response did not affect locomotor activity. In summary, this study for the first time identified an active component from the herbal medicine angelicae dahuricae radix that possesses robust antidepressant-like efficacy in mice. These data support further exploration for the possibility of developing auraptenol as a novel antidepressant agent in the treatment of major depression disorders.

Reply to: Rapid antidepressant effects and abuse liability of ketamine

Letter to the Editor: We would like to thank Yang and Hashimoto for their commentary and interest in our recent article that evaluated abuserelated effects of the N-methyl-D-aspartate (NMDA) receptor antagonists ketamine and MK-801 (Hillhouse et al. 2014). In this study, we reported that the high-affinity and selective NMDA receptor antagonist MK-801 produced a doseand time-dependent abuse-related facilitation of intracranial selfstimulation (ICSS) in rats. In contrast, the low-affinity NMDA receptor antagonist ketamine only depressed ICSS in rats and failed to produce an abuse-related facilitation on ICSS after acute treatment. Following repeated ketamine treatment, tolerance to the rate-decreasing effects of ketamine developed; however, ketamine still failed to produce an abuse-related increase on ICSS.We acknowledged that these results contrast with evidence for rare but well-documented cases of ketamine abuse in humans (McCambridge et al. 2007; Shek 2007) and for abuse-related ketamine effects in other preclinical models (Rocha et al. 1996; Suzuki et al. 2000). However, we also interpreted the dissociable effects of MK-801 and ketamine to suggest that ketaminemay produce effects mediated by targets other than NMDA receptors. One basis for non-NMDA ketamine effects could be stereoselectivity of pharmacology for ketamine enantiomers. Clinical and preclinical studies of ketamine, including our study cited above, most commonly use the racemate R,S (±)ketamine, which is comprised of equal parts S-ketamine and R-ketamine. S-ketamine is approximately three times more potent than R-ketamine for the PCP site on NMDA receptors and for mu-opioid receptors, but it is approximately sixfold less potent for sigma receptors (Hustveit et al. 1995). Furthermore, S-ketamine is twice as potent to block the NMDA channel (Zeilhofer et al. 1992), and in healthy human volunteers, S-ketamine was four times more potent than Rketamine to produce intoxicating effects, visual and auditory disturbances, and analgesia to experimentally induced ischemic pain (Oye et al. 1992). Recently, Zhang et al. (2014) reported that R-ketamine produced a reduction in time spent immobile in the forced swim test and tail suspension test in mice at 27–29 h and at 7 days after treatment, whereas, S-ketamine reduced time spent immobile in these tasks at 27–29 h, but not at day 7. The authors concluded that R-ketamine may be responsible for the prolonged antidepressant effects produced by the racemic form of ketamine, although a mechanism of action for this stereoselectivity was not proposed. To date, the antidepressant effects of R-ketamine have not been evaluated in clinical settings. However, clinical research does suggest that R-ketamine displays reduced psychotomimetic properties. For example, in healthy human volunteers, a subanesthetic dose of S-ketamine produced depersonalization, visual disturbances, auditory distortions, and disrupted attention, whereas an equimolar dose of R-ketamine did not produce psychotomimetic effects and instead produced a state of relaxation (Vollenweider et al. 1997). To our knowledge, abuse-related effects of ketamine enantiomers have not been compared. In conclusion, we agree with Yang and Hashimoto that pharmacological differences in ketamine enantiomers warrant further investigation in ICSS procedures and other preclinical procedures that evaluate abuse-related drug effects.

Iptakalim confers an antidepressant effect in a chronic mild stress model of depression through regulating neuro-inflammation and neurogenesis

Depression is a serious mental disorder in the world, but the underlying mechanisms remain unclear and the effective cures are scarce. Iptakalim (Ipt), an ATP-sensitive potassium (K-ATP) channel opener that can cross the blood-brain barrier freely, has been demonstrated to inhibit neuro-inflammation and enhance adult hippocampal neurogenesis. But it is unknown whether Ipt is beneficial to therapy of depression by modulating neurogenesis and neuro-inflammation. This study aimed to determine the potential antidepressant efficacy of Ipt in a chronic mild stress (CMS) mouse model of depression. We showed that treatment with Ipt (10 mg/kg/day, i.p) for 4 wk restored the decrease of sucrose preference and shortened the immobile time in forced swimming tests (FST) and tail suspension tests (TST) in CMS model mice. We further found that Ipt reversed the CMS-induced reduction of the adult hippocampal neurogenesis and improved cerebral insulin signalling in the CMS mice. Furthermore, Ipt negatively regulated nod-like receptor protein 3 (NLRP3) expression and, in turn, inhibited microglia-mediated neuro-inflammation by suppressing the activation of NLRP3-inflammasome/caspase-1/interleukin 1β axis in the hippocampus of CMS mice. Taken together, our findings demonstrate that Ipt plays a potential antidepressant role in CMS model mice through regulating neuro-inflammation and neurogenesis, which will provide potential for Ipt in terms of opening up novel therapeutic avenues for depression.

Synthesis and biological evaluation of a series of benzoxazole/benzothiazole-containing 2,3-dihydrobenzo[b][1,4]dioxine derivatives as potential antidepressants

A series of benzoxazole/benzothiazole-2,3-dihydrobenzo[b][1,4]dioxine derivatives (5a–5d and 8a–8j) was synthesized. Compounds were evaluated for binding affinities at the 5-HT1A and 5-HT2A receptors. Antidepressant activities of the compounds were screened using the forced swimming test (FST) and the tail suspension test (TST). The results indicated that the compounds exhibited high affinities for the 5-HT1A and 5-HT2A receptors and showed a marked antidepressant-like activity. Compound 8g exhibited high affinities for the 5-HT1A (Ki=17nM) and 5-HT2A (Ki=0.71nM) receptors; it also produced a decrease of the immobility time and exhibited potent antidepressant-like effects in the FST and TST in mice.

Antidepressant-like activity of beta-carotene in unstressed and chronic unpredictable mild stressed mice

The antidepressant-like activity of beta-carotene in Swiss young male albino mice subjected to chronic unpredictable mild stress was evaluated. Beta-carotene (50 and 100mg/kg, p.o.) and imipramine (15mg/kg, p.o.) per se were administered for 21 successive days to separate groups of unstressed and stressed mice. Higher dose (100mg/kg) of beta-carotene and imipramine significantly decreased immobility period of mice in tail suspension test. These compounds significantly restored the reduced sucrose preference in stressed mice. There was no significant effect on locomotor activity of mice by the drugs. Beta-carotene significantly reversed stress-induced increase in brain catalase, monoamine oxidase (MAO-A), thiobarbituric acid-reactive substances (TBARS); and plasma nitrite and corticosterone levels; and increased stress-induced decrease in reduced glutathione levels. Thus, beta-carotene showed significant antidepressant-like activity in unstressed and stressed mice probably through inhibition of MAO-A and oxidative stress. Its antidepressant-like activity in stressed mice might also be due to decrease in plasma corticosterone levels.

Evaluation of Potential Antidepressant-Like Activity of Chalcone-1203 in Various Murine Experimental Depressant Models

Two classic animal behavior despair tests-the forced swimming test (FST) and the tail suspension test (TST) were used to evaluate antidepressant-like activity of a new chalcone compound, chalcone-1203 in mice. It was observed that chalcone-1203 at dose of 1, 5, and 10mg/kg significantly reduced the immobility time in the FST and TST in mice 30min after treatment. In addition, chalcone-1203 was found to exhibit significant oral activity in the FST in mice. It also produced a reduction in the ambulation in the open-field test in mice not previously habituated to the arena, but no effect in the locomotor activity in mice previously habituated to the open-field. The main monoamine neurotransmitters and their metabolites in mouse brain regions were also simultaneously determined by HPLC-ECD. It was found that chalcone-1203 significantly increased the concentrations of the main neurotransmitters 5-HT and NE in the hippocampus, hypothalamus and cortex. Chalcone-1203 also significantly reduced the ratio of 5-HIAA/5-HT in the hippocampus and cortex, shown down 5-HT metabolism compared with mice treated with stress vehicle. In conclusion, chalcone-1203 produced significant antidepressant-like activity, and the mechanism of action may be due to increased 5-HT and NE in the mouse hippocampus and cortex.

Antidepressant Effect of Dimeric Dipeptide GSB-106, an Original Low-Molecular-Weight Mimetic of BDNF

A large amount of clinical and experimental data suggest the involvement of neurotrophins, in particular the brain-derived neurotrophic factor (BDNF), in depression pathogenesis. However, the therapeutic use of BDNF is limited because of its instability in biological fluids, poor blood-brain barrier (BBB) permeability, and the presence of side effects. A low-molecular-weight mimetic GSB-106, which is a substituted dimeric dipeptide bis(N-monosuccinyl-L-seryl-L-lysine)hexamethylenediamide, was designed and synthesized based on the BDNF fourth loop structure at the V.V. Zakusov Institute of Pharmacology (RAMS). GSB-106 was found to exhibit an antidepressant activity in various models of depressive-like state when administered intraperitoneally to outbred mice and rats. An effect for the substance, when administered daily for 4-5 days, was detected in the Porsolt forced swimming test (0.1 and 1.0 mg/kg) and in the tail suspension test in mice (1.0 and 1.5 mg/ kg). An effect for GSB-106 at doses of 0.1 and 0.5 mg/kg was observed after a single application in experiments on rats in the Nomura water wheel test. The obtained evidence supports the hypothesis on the involvement of BDNF in the pathogenesis of various depression conditions, thus opening prospects for searching for new original antidepressants.

Antidepressant-like activity of the adenosine A2A receptor antagonist, istradefylline (KW-6002), in the forced swim test and the tail suspension test in rodents

RationaleDepression is common in Parkinson's disease (PD) but its response to classical antidepressants is not clear. The adenosine A2A antagonist istradefylline is effective in the treatment of the motor symptoms of PD but inhibition of the adenosine A2A receptor may also induce antidepressant-like effects. ObjectiveWe have investigated whether istradefylline might be effective in treating depression in PD using the forced swimming test (FST) and the tail suspension test (TST) in rodents. ResultsIstradefylline significantly decreased immobility time in the FST in both rats and mice (0.16mg/kg and higher) with comparable efficacy to an equivalent dose of the tricyclic antidepressants, desipramine and imipramine. Both 8-OH-DPAT (5-HT1A agonist) and quinpirole (D2 agonist) also reduced the immobility time. The istradefylline-induced reduction of immobility time was attenuated by corticosterone. In addition, the combined use of a sub-threshold dose of istradefylline and the serotonin-noradrenaline reuptake inhibitor venlafaxine ameliorated depression-like behavior in the mouse FST. In the mouse TST, istradefylline (0.08mg/kg and higher) decreased immobility time. Moreover, co-administration of istradefylline with paroxetine or fluoxetine (selective serotonin reuptake inhibitors) or deprenyl (MAO-B inhibitor) at doses that did not show antidepressant-like effects when administered alone, resulted in a significant reduction in immobility time. ConclusionsIstradefylline alone or co-administered with currently available antidepressants, may be useful for the treatment of depression as well as motor symptoms of PD. Its effects might be, at least in part, attributable to modulation of hypothalamic–pituitary–adrenal axis.

Antidepressant-like activity of turmerone in behavioral despair tests in mice

BackgroundThe present study was undertaken to evaluate the anti-depressive activity of turmerone after one-week administration by using a mouse forced swimming test (FST) and tail suspension test (TST).MethodsAnimals were divided into four groups (n = 10 /group): control (0.9% saline), the three doses of turmerone (1.25, 2.5, 5.0 mg/kg) for one-week treatment. To assess the effect of turmerone on locomotor activity, mice were evaluated in the open-field paradigm. Forced swimming test (FST) and Tail suspension test (TST) were used to take as a measure of antidepressant activity. The probable mechanisms of action of the anti-depressive effect of turmerone was also investigated by measuring the activity of monoamine oxidase-A and corticosterone levels in the blood and the levels of monoamines in the cortex, striatum, hippocampus and hypothalamus of the mice.ResultsTurmerone (2.5, 5.0 mg/kg, p.o.) significantly reduced the immobility time of mice in both the FST and TST, but it did not significantly affect the ambulatory and total movements of mice. However, hyperactivity might explain the results. In addition, turmerone decreased the corticosterone level in the blood while it increased the levels of 5-HT in cortex, striatum, hippocampus, and hypothalamus, the level of NE in striatum and hippocampus, the levels of MHPG and DOPAC in hypothalamus, the level of 5-HIAA in striatum, and the level of DA in striatum, hippocampus, and hypothalamus. Turmerone (2.5, 5.0 mg/kg) decreased the activity of MAO-A in the frontal cortex and hippocampus of mouse brain.ConclusionsAfter one-week administration, turmerone produced antidepressant-like effects. The mechanisms of action of anti-depressive effect of turmerone seemed to involve an increase of the monoamines level decreasing the MAO-A activity and the stress of mice.

Antidepressant-like activity of resveratrol treatment in the forced swim test and tail suspension test in mice: The HPA axis, BDNF expression and phosphorylation of ERK

Resveratrol is a natural polyphenol enriched in Polygonum cuspidatum and has diverse biological activities. There is only limited information about the antidepressant-like effect of resveratrol. The present study assessed whether resveratrol treatment (20, 40 and 80mg/kg, i.p., 21days) has an antidepressant-like effect on the forced swim test (FST) and tail suspension test (TST) in mice and examined what its molecular targets might be. The results showed that resveratrol administration produced antidepressant-like effects in mice, evidenced by the reduced immobility time in the FST and TST, while it had no effect on the locomotor activity in the open field test. Resveratrol treatment significantly reduced serum corticosterone levels, which had been elevated by the FST and TST. Moreover, resveratrol increased brain-derived neurotrophic factor (BDNF) protein and extracellular signal-regulated kinase (ERK) phosphorylation levels in the prefrontal cortex and hippocampus. All of these antidepressant-like effects of resveratrol were essentially similar to those observed with the clinical antidepressant, fluoxetine. These results suggest that the antidepressant-like effects of resveratrol in the FST and TST are mediated, at least in part, by modulating hypothalamic–pituitary–adrenal axis, BDNF and ERK phosphorylation expression in the brain region of mice.