Behavioral Engagement With Playable Objects Resolves Stress-Induced Adaptive Changes by Reshaping the Reward System.

BACKGROUND: The reward system regulates motivated behavior, and repeated practice of specific motivated behavior might conversely modify the reward system. However, the detailed mechanisms by which they reciprocally regulate each other are not clearly understood. METHODS: Mice subjected to chronic restraint stress show long-lasting depressive-like behavior, which is rescued by continual engagement with playable objects. A series of molecular, pharmacological, genetic, and behavioral analyses, combined with microarray, liquid chromatography, and chemogenetic tools, are used to investigate the neural mechanisms of antidepressive effects of playable objects. RESULTS: Here, we show that repeated restraint induces dopamine surges into the nucleus accumbens-lateral shell (NAc-lSh), which cause upregulation of the neuropeptide PACAP in the NAc-lSh. As repeated stress is continued, the dopamine surge by stressors is adaptively suppressed without restoring PACAP upregulation, and the resulting enhanced PACAP inputs from NAc-lSh neurons to the ventral pallidum facilitate depressive-like behaviors. Continual engagement with playable objects in mice subjected to chronic stress remediates reduced dopamine response to new stressors, enhanced PACAP upregulation, and depressive-like behaviors. Overactivation of dopamine D1 receptors over the action of D2 receptors in the NAc-lSh promotes depressive-like behaviors. Conversely, inhibition of D1 receptors or PACAP upregulation in the NAc-lSh confers resilience to chronic stress-induced depressive-like behaviors. Histochemical and chemogenetic analyses reveal that engagement with playable objects produces antidepressive effects by reshaping the ventral tegmental area-to-NAc-lSh and NAc-lSh-to-ventral pallidum circuits. CONCLUSIONS: These results suggest that behavioral engagement with playable objects remediates depressive-like behaviors by resolving stress-induced maladaptive changes in the reward system.

Modulation of Ion Channels and Receptors by p11 (S100A10).

p11 (S100A10, annexin II light chain, calpactin I light chain) is a multifunctional protein that forms a heterotetrameric complex with Annexin A2, particularly at cell membranes. p11, alone or together with Annexin A2, interacts with several ion channels and receptors and regulates their cellular localization and function. Altered levels of p11 are implicated in the pathophysiology of several forms of cancer, psychiatric disorders, and neurodegeneration. Via interactions with ion channels and receptors, p11 modulates therapeutic actions of drugs targeting brain disorders. By serving as a plasminogen receptor, p11 plays an important role in plasmin generation, fibrinolysis, angiogenesis, tumor progression, and metastasis. Here, we review mechanisms whereby p11 regulates functions of ion channels and receptors in health and disease states.

AIM2 inflammasome contributes to brain injury and chronic post-stroke cognitive impairment in mice.

Although over one-third of stroke patients may develop post-stroke cognitive impairment (PSCI), the mechanisms underlying PSCI remain unclear. We explored here, the involvement of post-stroke inflammasomes in long-term PSCI development, using a 45 min-middle cerebral artery occlusion (MCAO)/reperfusion-induced PSCI model. Immunohistological assessment on day 1, 3, and 7 was followed by cognitive function test 28 days post-stroke. Evaluation of inflammasome sensor gene expression in aged mouse brains showed dominant expression of absent in melanoma 2 (Aim2) in 6-, 12-, and 18-month-old mouse brains. AIM2 mRNA and protein increased until 7 days post-stroke. PSCI decreased anxiety in elevated plus maze test and impaired spatial learning and memory functions in Morris water maze test 28 days post-stroke. AIM2 and other inflammasome subunit immunoreactivities, including those for caspase-1, interleukin (IL)-1ß, and IL-18, were higher in the hippocampus and cortex of the PSCI than in those of the sham group 7 days post-stroke. AIM2 immunoreactivity of the PSCI group was primarily co-localized with Iba-1 (microglial marker) and CD31 (endothelial cell marker) immunoreactivities but not NeuN (neuronal marker) and GFAP (astrocyte marker) immunoreactivities, suggesting that microglia or endothelial cell-induced AIM2 production mediated PSCI pathogenesis. Additionally, inflammasome-induced pyroptosis might contribute to acute and chronic neuronal death after stroke. AIM2 knockout (KO) and Ac-YVAD-CMK-induced caspase-1 inhibition in mice significantly improved cognitive function and reversed brain volume in the hippocampus relative to those in stroke mice. Conclusively, AIM2 inflammasome-mediated inflammation and pyroptosis likely aggravated PSCI; therefore, targeting and controlling AIM2 inflammasome could potentially treat PSCI.

NADPH oxidase mediates depressive behavior induced by chronic stress in mice.

Stress is a potent risk factor for depression, yet the underlying mechanism is not clearly understood. In the present study, we explored the mechanism of development and maintenance of depression in a stress-induced animal model. Mice restrained for 2 h daily for 14 d showed distinct depressive behavior, and the altered behavior persisted for >3 months in the absence of intervention. Acute restraint induced a surge of oxidative stress in the brain, and stress-induced oxidative stress progressively increased with repetition of stress. In vitro, the stress hormone glucocorticoid generated superoxide via upregulation of NADPH oxidase. Consistently, repeated restraints increased the expression of the key subunits of NADPH oxidase, p47phox and p67phox, in the brain. Moreover, stressed brains markedly upregulated the expression of p47phox to weak restress evoked in the poststress period, and this molecular response was reminiscent of amplified ROS surge to restress. Pharmacological inhibition of NADPH oxidase by the NADPH oxidase inhibitor apocynin during the stress or poststress period completely blocked depressive behavior. Consistently, heterozygous p47phox knock-out mice (p47phox(+/-)) or molecular inhibition of p47phox with Lenti shRNA-p47phox in the hippocampus suppressed depressive behavior. These results suggest that repeated stress promotes depressive behavior through the upregulation of NADPH oxidase and the resultant metabolic oxidative stress, and that the inhibition of NADPH oxidase provides beneficial antidepression effects.

The nuclear inclusion a (NIa) protease of turnip mosaic virus (TuMV) cleaves amyloid-ß.

BACKGROUND: The nuclear inclusion a (NIa) protease of turnip mosaic virus (TuMV) is responsible for the processing of the viral polyprotein into functional proteins. NIa was previously shown to possess a relatively strict substrate specificity with a preference for Val-Xaa-His-Gln↓, with the scissile bond located after Gln. The presence of the same consensus sequence, Val(12)-His-His-Gln(15), near the presumptive α-secretase cleavage site of the amyloid-ß (Aß) peptide led us to hypothesize that NIa could possess activity against Aß. METHODOLOGY/PRINCIPAL FINDINGS: Western blotting results showed that oligomeric as well as monomeric forms of Aß can be degraded by NIa in vitro. The specific cleavage of Aß was further confirmed by mass spectrometry analysis. NIa was shown to exist predominantly in the cytoplasm as observed by immunofluorescence microscopy. The overexpression of NIa in B103 neuroblastoma cells resulted in a significant reduction in cell death caused by both intracellularly generated and exogenously added Aß. Moreover, lentiviral-mediated expression of NIa in APP(sw)/PS1 transgenic mice significantly reduced the levels of Aß and plaques in the brain. CONCLUSIONS/SIGNIFICANCE: These results indicate that the degradation of Aß in the cytoplasm could be a novel strategy to control the levels of Aß, plaque formation, and the associated cell death.

A modified preparation (LMK03) of the oriental medicine Jangwonhwan reduces Abeta(1-42) level in the brain of Tg-APPswe/PS1dE9 mouse model of Alzheimer disease.

ETHNOPHARMACOLOGICAL RELEVANCE: The oriental medicine Jangwonhwan, which is a boiled extract of 12 medicinal herbs/mushroom, has been prescribed for patients with cognitive dysfunction. Recently, a modified recipe of Jangwonhwan (LMK02-Jangwonhwan) consisting of seven medicinal plants/mushroom, was shown to have a therapeutic potential to ameliorate AD-like pathology. AIM OF THE STUDY: It was investigated whether a further reduction of Jangwonhwan (LMK03-Jangwonhwan) retains the potency to suppress the AD-like pathology. MATERIALS AND METHODS: The transgenic mice of Alzheimer disease, Tg-APPswe/PS1dE9, were fed LMK03-Jangwonhwan consisting of two of the herbs, white Poria cocos (Schw.) Wolf and Angelica gigas Nakai, which could protect the AD-like pathology at 300 mg/kg/day of dose for 3 months. In vitro cell biological study, immunohistological and ELISA (enzyme-linked immunosorbent assay) analyses were used to assess its neuroprotective effects against Abeta-induced cell death, and the Abeta accumulation and plaque deposition in the brain. RESULTS: In vitro study with SH-SY5Y neuroblastoma cells showed that LMK03-Jangwonhwan could protect from cytotoxicity induced by hydrogen peroxide or oligomeric Abeta(1-42). Tg-APPswe/PS1dE9 mice were administered LMK03-Jangwonhwan at 300 mg/kg/day for 3 months from 4.5 months of age. Immunohistological and ELISA analyses showed that LMK03-Jangwonhwan partially reduced Abeta(1-42)and Abeta(1-40) levels and beta-amyloid plaque deposition in the brain of Tg-APPswe/PS1dE9 mice. However, LMK03-Jangwonhwan poorly suppressed accumulation of reactive oxidative stress in the hippocampus of Tg-APPswe/PS1dE9 mice and inefficiently improved the expression of phospho-CREB and calbindin, the cellular factors that were down-regulated in AD-like brains. CONCLUSIONS: These results suggest that LMK03-Jangwonhwan has a potency to inhibit AD-like pathology at a detectable level, but LMK03 is not likely to retain the major ability of LMK02-Jangwonhwan to modify AD pathology in several AD-related molecular parameters.

Oriental medicine Jangwonhwan reduces Abeta(1-42) level and beta-amyloid deposition in the brain of Tg-APPswe/PS1dE9 mouse model of Alzheimer disease.

ETHNOPHARMACOLOGICAL RELEVANCE: Jangwonhwan, a boiled extract of 12 medicinal plants/mushroom including Korean red ginseng (Panax ginseng C.A. Meyer), has been prescribed for patients with cognitive dysfunction and are believed to induce brain activity enhancement, provide light sedation, and facilitate sound sleep. AIM OF THE STUDY: The present study was carried out to investigate whether Jangwonhwan has a beneficial effect on the brain of Alzheimer disease. MATERIALS AND METHODS: The transgenic mice of Alzheimer disease, Tg-APPswe/PS1dE9, were fed a modified recipe of Jangwonhwan consisting of a boiled extract of 7 herbs/mushroom (called LMK02-Jangwonhwan) at 400mg/kg/day of dose for 3 months from 4.5 months of age. Immunohistological and ELISA analyses were used to assess the Abeta accumulation and plaque deposition in the brain. Other in vitro and in vivo works were performed to understand the underlying mechanism. RESULTS: LMK02-Jangwonhwan notably reduced Abeta(1-42) and Abeta(1-40) levels, concomitantly with a reduction of plaque deposition, in the brain of Tg-APPswe/PS1dE9 mice. LMK02-Jangwonhwan partially suppressed oxidative stress accumulation, and prevented the down-regulation of phospho-CREB and calbindin typically seen in the hippocampus of AD-like brains. In vitro study with SH-SY5Y neuroblastoma cells showed that LMK02-Jangwonhwan inhibited oxidative stress and Abeta-induced neurotoxicity. CONCLUSION: The present study suggests that LMK02-Jangwonhwan confers a therapeutic potential to ameliorate AD-like pathology in the brain of Tg-APPswe/PS1dE9 mice.

Fluoxetine attenuates kainic acid-induced neuronal cell death in the mouse hippocampus.

Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) and one of the commonly prescribed antidepressants. Numerous clinical observations and animal studies indicate that fluoxetine enhances the anticonvulsant potencies of several antiepileptic drugs. In the previous report, we showed that fluoxetine strongly protects against delayed cerebral ischemic injury. In the present study, the authors investigated whether fluoxetine has a beneficial effect on KA-induced neuronal cell death. An intracerebroventricular (i.c.v.) injection of 0.94 nmol (0.2 microg) of KA produced typical neuronal cell death both in CA1 and CA3 regions of the hippocampus. Although, there was no significant difference in the time course or severity of epileptic behavior, the systemic administration of fluoxetine 30 min before KA administration significantly attenuated this neuronal cell death. Fluoxetine was found to suppress neuronal cell loss when injected at 10 mg/kg and the effect was enhanced at 50 mg/kg. Furthermore, this fluoxetine-induced neuroprotection was accompanied by marked improvements in memory impairment, as determined by passive avoidance tests. KA-induced gliosis and proinflammatory marker (COX-2, IL-1beta, and TNF-alpha) inductions were also suppressed by fluoxetine administration. It is interesting to note here that fluoxetine treatment suppressed NF-kappaB activity dose-dependently in KA-treated mouse brains, suggesting that this explains in part its anti-inflammatory effect. Together, these results suggest that fluoxetine has therapeutic potential in terms of suppressing KA-induced pathogenesis in the brain, and that these neuroprotective effects are associated with its anti-inflammatory effects.

SK-PC-B70M confers anti-oxidant activity and reduces Abeta levels in the brain of Tg2576 mice.

SK-PC-B70M is an oleanolic-glycoside saponin-enriched fraction derived from the root of Pulsatilla koreana. Recently, it was reported that hederacolchiside-E is an active ingredient of SK-PC-B70M that confers a neuroprotective effect against the cytotoxicity induced by Abeta(1-42) in SK-N-SH neuroblastoma cells. SK-PC-B70M improves scopolamine-induced impairments of spatial working memory in rats. In the present study, we investigated whether SK-PC-B70M has a beneficial effect on the Tg2576 murine model of Alzheimer's disease. ELISA analysis revealed that the levels of soluble and insoluble forms of Abeta(1-42) in Tg2576 mice fed SK-PC-B70M (2000 ppm) from 11 months to 16 months of age were reduced to, respectively, 66% and 79% of the control Tg2576 mice. Anti-Abeta antibody-stained brain sections of Tg2576 mice with SK-PC-B70M (2000 ppm) consistently showed a reduction in plaque formation in the brain. Western blot analyses showed altered expressions of various cellular factors, such as up-regulation of transthyretin, phospho-ERK, and phospho-CREB in the brain treated with SK-PC-B70M. SK-PC-B70M suppressed the neuronal toxicity induced by H(2)O(2) in primary cortical culture. Moreover, biochemical and immunohistochemical analyses showed that the levels of malondialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE), oxidized by-products of lipid peroxidation, were notably reduced in the hippocampus of Tg2576 mice treated with SK-PC-B70M compared with the Tg2576 control. These results suggest that SK-PC-B70M attenuates AD-like pathology in the brain of Tg2576 mice.