A comprehensive metabolomics investigation of hippocampus, serum, and feces affected by chronic fluoxetine treatment using the chronic unpredictable mild stress mouse model of depression.

A metabolomic investigation of depression and chronic fluoxetine treatment was conducted using a chronic unpredictable mild stress model with C57BL/6N mice. Establishment of the depressive model was confirmed by body weight measurement and behavior tests including the forced swim test and the tail suspension test. Behavioral despair by depression was reversed by four week-treatment with fluoxetine. Hippocampus, serum, and feces samples collected from four groups (control + saline, control + fluoxetine, model + saline, and model + fluoxetine) were subjected to metabolomic profiling based on ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. Alterations in the metabolic patterns were evident in all sample types. The antidepressant effects of fluoxetine appeared to involve various metabolic pathways including energy metabolism, neurotransmitter synthesis, tryptophan metabolism, fatty acid metabolism, lipid metabolism, and bile acid metabolism. Predictive marker candidates of depression were identified, including ß-citryl-L-glutamic acid (BCG) and docosahexaenoic acid (DHA) in serum and chenodeoxycholic acid and oleamide in feces. This study suggests that treatment effects of fluoxetine might be differentiated by altered levels of tyramine and BCG in serum, and that DHA is a potential serum marker for depression with positive association with hippocampal DHA. Collectively, our comprehensive study provides insights into the biochemical perturbations involved in depression and the antidepressant effects of fluoxetine.

The new stimulant designer compound pentedrone exhibits rewarding properties and affects dopaminergic activity.

Cathinone derivatives are new recreational drugs known to produce psychostimulant effects. However, unlike other psychostimulants, the addictive potential of cathinone derivatives has not been widely studied. Here, we investigated the effects of pentedrone, a type of cathinone derivative, on the dopaminergic system using reverse transcription polymerase chain reaction and Western blot. We also evaluated the addictive potential of pentedrone using conditioned place preference and self-administration. We found that pentedrone increased the mRNA expression of dopamine 1 receptor, dopamine 2 receptor and dopamine transporter, as well as induced phosphorylation of cAMP response element-binding protein in PC-12 cells. Additionally, pentedrone at 3 and 10 mg/kg significantly increased conditioned place preference in mice, while pentedrone at 0.3 mg/kg/infusion significantly increased self-administration in rats. Finally, we found that acute administration of pentedrone enhanced locomotor activity in a dose-dependent manner. Collectively, these data suggest that the addictive properties of pentedrone may be due to its effects on the dopaminergic system.

Metabolomic identification of biochemical changes induced by fluoxetine and imipramine in a chronic mild stress mouse model of depression.

Metabolomics was applied to a C57BL/6N mouse model of chronic unpredictable mild stress (CMS). Such mice were treated with two antidepressants from different categories: fluoxetine and imipramine. Metabolic profiling of the hippocampus was performed using gas chromatography-mass spectrometry analysis on samples prepared under optimized conditions, followed by principal component analysis, partial least squares-discriminant analysis, and pair-wise orthogonal projections to latent structures discriminant analyses. Body weight measurement and behavior tests including an open field test and the forced swimming test were completed with the mice as a measure of the phenotypes of depression and antidepressive effects. As a result, 23 metabolites that had been differentially expressed among the control, CMS, and antidepressant-treated groups demonstrated that amino acid metabolism, energy metabolism, adenosine receptors, and neurotransmitters are commonly perturbed by drug treatment. Potential predictive markers for treatment effect were identified: myo-inositol for fluoxetine and lysine and oleic acid for imipramine. Collectively, the current study provides insights into the molecular mechanisms of the antidepressant effects of two widely used medications.

Strain differences in the chronic mild stress animal model of depression and anxiety in mice.

Chronic mild stress (CMS) has been reported to induce an anhedonic-like state in mice that resembles some of the symptoms of human depression. In the present study, we used a chronic mild stress animal model of depression and anxiety to examine the responses of two strains of mice that have different behavioral responsiveness. An outbred ICR and an inbred C57BL/6 strain of mice were selected because they are widely used strains in behavioral tests. The results showed that the inbred C57BL/6 and outbred ICR mice were similarly responsive to CMS treatment in sucrose intake test (SIT) and open field test (OFT). However, the two strains showed quite different responses in forced swimming test (FST) and novelty-suppressed feeding (NSF) test after 3 weeks of CMS treatment. Only C57BL/6 mice displayed the depression- and anxiety-like behavioral effects in response to CMS treatment in FST and NSF test. Our results suggest that there are differences in responsiveness to CMS according to the different types of strain of mice and behavioral tests. Therefore, these results provide useful information for the selection of appropriate behavioral methods to test depression- and anxiety-like behaviors using CMS in ICR and C57BL/6 mice.

Transient receptor potential vanilloid type 1 channel may modulate opioid reward.

Transient receptor potential vanilloid type 1 (TRPV1), a nonselective cation channel, is a well-known pain-related receptor. TRPV1 involvement in morphine-induced antinociception, tolerance, and withdrawal symptoms has been previously reported. Emerging evidence indicates that TRPV1 may be related to both the cellular and behavioral effects of addictive drugs. In the present study, we investigated the role of TRPV1 in morphine reward using the conditioned place preference (CPP) paradigm in mice. Repeated morphine treatments upregulated TRPV1 expression in the dorsal striatum (DSt). Treatment with a TRPV1 agonist potentiated morphine reward, and pretreatment with TRPV1 antagonists attenuated these effects. Microinjection of a selective TRPV1 antagonist into the DSt significantly inhibited morphine-CPP. In addition, treatment with a TRPV1 antagonist suppressed morphine-induced increases in µ-opioid receptor binding, adenylyl cyclase 1 (AC1), p38 mitogen-activated protein kinase (p38 MAPK), and nuclear factor kappa B (NF-κB) expression in the DSt. Administering a p38 inhibitor not only prevented morphine-CPP, but also prevented morphine-induced NF-κB and TRPV1 activation in the DSt. Furthermore, injecting an NF-κB inhibitor significantly blocked morphine-CPP. Our findings suggest that TRPV1 in the DSt contribute to morphine reward via AC1, p38 MAPK, and NF-κB. Brain TRPV1 may serve as a novel therapeutic target to treat morphine-addictive disorders.

Anxiolytic effects of Julibroside C1 isolated from Albizzia julibrissin in mice.

Julibroside C1 is a saponin-containing compound isolated from Albizzia julibrissin Durazz. In this study, we investigated the putative anxiolytic effects of Julibroside C1 using the elevated plus maze (EPM) in mice. Julibroside C1 at doses of 0.5 and 1 mg/kg significantly increased the time spent in the open arms and the number of entries into the open arms of the EPM compared to the control group. Moreover, the anxiolytic-like effects of Julibroside C1 (0.5 mg/kg) were blocked by WAY-100635 (5-HT1A receptor antagonist), bicuculline (GABA(A) receptor antagonist), and flumazenil (antagonist of the GABA(A) receptor benzodiazepine site). However, Julibroside C1 did not change locomotor activity or induce myorelaxant effects. We used quantitative receptor autoradiography to investigate the effects of Julibroside C1 on alterations in mouse brain receptors. After acute treatment with Julibroside C1 (0.5 mg/kg), [(3)H]-8-OH-DPAT binding was significantly decreased in the CA1 region of the hippocampus and [(3)H]-flunitrazepam binding was decreased remarkably in the cingulate cortex region. However, [(3)H]-muscimol binding did not show a significant change in any brain region. Taken together, our findings suggest that Julibroside C1 shows anxiolytic-like effects, which might be mediated by the 5-HT1A and GABA(A)-benzodiazepine receptor systems.

5-HT(1A) receptor binding in the dorsal raphe nucleus is implicated in the anxiolytic-like effects of Cinnamomum cassia.

Previously we reported that the 50% EtOH extract of Cinnamomum cassia (C. cassia) possesses anxiolytic-like activity in the mouse elevated plus maze (EPM) test. This activity was blocked by the 5-HT(1A) receptor antagonist, WAY 100635. Therefore, in order to investigate the effect of C. cassia on 5-HT(1A) receptor binding, quantitative autoradiography of 5-HT(1A) receptors was carried out in brains of mice treated acutely and repeatedly with C. cassia. Binding of [(3)H]8-OH-DPAT to the 5-HT(1A) receptor was investigated in the mouse brain. After a single treatment of C. cassia (750 mg/kg, p.o.), [(3)H]8-OH-DPAT binding showed a significant increase in the dorsal raphe nucleus (DRN). After repeated treatment with C. cassia (100mg/kg, once a day for 5 days, p.o.), [(3)H]8-OH-DPAT binding showed no significant change in any brain region. Taken together, the anxiolytic-like effect of the 50% EtOH extract of C. cassia might be mediated by region specific change of 5-HT(1A) receptors in the dorsal raphe nucleus.

Lonicera japonica THUNB. protects 6-hydroxydopamine-induced neurotoxicity by inhibiting activation of MAPKs, PI3K/Akt, and NF-κB in SH-SY5Y cells.

In this study, we investigated the neuroprotective effects of Lonicera japonica THUNB. extract (LJ) on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in SH-SY5Y cells. We found that LJ significantly increased cell viability decrease, lactate dehydrogenase release (LDH), morphological changes, nuclear condensation, fragmentation, and reactive oxygen species (ROS) production induced by 6-OHDA in SH-SY5Y cells. The cytoprotection afforded by pretreatment with LJ was associated with increases of the glutathione (GSH) level, superoxide dismutase (SOD) activity, and catalase (CAT) activity in 6-OHDA-induced SH-SY5Y cells. In addition, LJ strikingly inhibited 6-OHDA-induced mitochondrial dysfunctions including reduction of mitochondria membrane potential (MMP) and activation of cleaved poly-ADP-ribose polymerase (PARP), cleaved caspase-3, cleaved caspase-9, increased Bax, as well as decreased Bcl-2 and Bcl-xL. Additionally, LJ dramatically attenuated 6-OHDA-induced phosphorylation of c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 1/2 (ERK 1/2), and phosphoinositide 3-kinase (PI3K)/Akt. Meanwhile, LJ counteracted nuclear factor-κB (NF-κB) activation by blocking its translocation to the nucleus. These findings suggest that LJ has a potent anti-parkinsonism; this effect was mediated, at least in part, by inhibition of neurotoxicity, apoptotic cascade events, and oxidative stress via activation of MAPKs, PI3K/Akt, and NF-κB.

Alterations in the emotional and memory behavioral phenotypes of transient receptor potential vanilloid type 1-deficient mice are mediated by changes in expression of 5-HT1A, GABA(A), and NMDA receptors.

The transient receptor potential vanilloid type 1 channel (TRPV1) receptors are expressed in various regions of the brain. Much less is known about whether TRPV1 receptors affect higher brain functions. In the present study, we demonstrated that TRPV1-knockout (TRPV1KO) mice showed antidepressant-like behaviors in a novelty-suppressed feeding test and forced swim test when compared to wild-type (WT) mice. Additionally, TRPV1KO mice exhibited increased aggressiveness and reduced social interactions in a social dominance test and social interaction test. TRPV1KO mice showed reduced short-term memory and normal long-term memory in a novel object recognition test and passive avoidance test versus WT mice. Based on these behavioral data, we investigated changes in specific receptors related to depression, anxiety, and memory in the brains of TRPV1KO and WT mice. Binding of [(3)H]-8-OH-DPAT was significantly higher in the frontal associated cortex (FrA), nucleus accumbens (NAc), and the cingulate cortex (CC) of TRPV1KO mice than WT mice, while the expression of 5-HT(1A) receptors was higher in the FrA, NAc, and cortex of TRPV1KO mice than WT mice. [(3)H]-flunitrazepam binding was also significantly higher in the FrA, striatum (CPU), and the CC of TRPV1KO versus WT mice. In contrast, [(3)H]-musicmol binding in the FrA, CPU, NAc, CC, and the dentate gyrus (DG) was significantly lower in TRPV1KO mice than WT mice. The expression of GABA(A)γ(2) was higher in the NAc, CPU, and cortex of TRPV1KO versus WT mice, whereas the expression of GABA(A)α(2) was lower in the FrA, CPU, NAc, and cortex in TRPV1KO mice than WT mice. Finally, [(3)H]-MK-801 binding was decreased in the CPU and CA1 of TRPV1KO versus WT mice. The expression of NR2A was lower in the hippocampus of TRPV1KO versus WT mice. These data suggest that the loss of TRPV1 results in antidepressant-like, anxiolytic, abnormal social and reduced memorial behaviors due to changes in expression of 5-HT(1A), GABA(A,) and NMDA receptors. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

Loganin protects against hydrogen peroxide-induced apoptosis by inhibiting phosphorylation of JNK, p38, and ERK 1/2 MAPKs in SH-SY5Y cells.

We investigated the mechanisms underlying the protective effects of loganin against hydrogen peroxide (H(2)O(2))-induced neuronal toxicity in SH-SY5Y cells. The neuroprotective effect of loganin was investigated by treating SH-SY5Y cells with H(2)O(2) and then measuring the reduction in H(2)O(2)-induced apoptosis using 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release assays. Following H(2)O(2) exposure, Hoechst 33258 staining indicated nuclear condensation in a large proportion of SH-SY5Y cells, along with an increase in reactive oxygen species (ROS) production and an intracellular decrease in mitochondria membrane potential (MMP). Loganin was effective in attenuating all the above-stated phenotypes induced by H(2)O(2). Pretreatment with loganin significantly increased cell viability, reduced H(2)O(2)-induced LDH release and ROS production, and effectively increased intracellular MMP. Pretreatment with loganin also significantly decreased the nuclear condensation induced by H(2)O(2). Western blot data revealed that loganin inhibited the H(2)O(2)-induced up-regulation of cleaved poly (ADP-ribose) polymerase (PARP) and cleaved caspase-3, increased the H(2)O(2)-induced decrease in the Bcl-2/Bax ratio, and attenuated the H(2)O(2)-induced release of cytochrome c from mitochondria to the cytosol. Furthermore, pretreatment with loganin significantly attenuated the H(2)O(2)-induced phosphorylation of c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and extracellular signal-regulated kinase 1/2 (ERK 1/2). These results suggest that the protective effects of loganin against H(2)O(2)-induced apoptosis may be due to a decrease in the Bcl-2/Bax ratio expression due to the inhibition of the phosphorylation of JNK, p38, and ERK 1/2 MAPKs. Loganin's neuroprotective properties indicate that this compound may be a potential therapeutic agent for the treatment of neurodegenerative diseases.

The neuroprotective effects of Lonicera japonica THUNB. against hydrogen peroxide-induced apoptosis via phosphorylation of MAPKs and PI3K/Akt in SH-SY5Y cells.

We investigated the neuroprotective effects of Lonicera japonica THUNB. (Caprifoliaceae) (LJ) extract against hydrogen peroxide (H(2)O(2)), a toxin created by oxidative stress and implicated in neurodegenerative diseases, in human SH-SY5Y neuroblastoma cells. We examined the effects of LJ against H(2)O(2)-induced cytotoxicity, apoptosis, the production of reactive oxygen species (ROS), the proteolysis of cleaved poly-ADP-ribose polymerase (PARP), and the expression of Bcl-2, Bcl-xL, and cleaved caspase-3. Moreover, we attempted to determine whether LJ suppressed the phosphorylation of Akt, c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and extracellular signal-regulated kinase 1/2 (ERK 1/2). We found that LJ improved cell viability, inhibited cytotoxicity and apoptosis, and attenuated elevations in ROS and nuclear condensation. In addition, LJ showed radical scavenging ability in 2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethyl-benzthiazoline-6-sulfonic acid) (ABTS) assays. Western blot data revealed that LJ inhibited H(2)O(2)-induced up- and down-regulation of cleaved PARP, cleaved caspase-3, Bcl-2, and Bcl-xL. Furthermore, LJ significantly attenuated the H(2)O(2)-induced phosphorylation of Akt, JNK, p38 MAPK, and ERK1/2. These results demonstrate that LJ possesses potent neuroprotective activity. Its potential to treat neurodegenerative diseases warrants further research.