Activation of 5-HT2 receptors enhances the release of acetylcholine in the prefrontal cortex and hippocampus of the rat

The role of 5-HT2 receptors in the regulation of acetylcholine (ACh) release was examined in the medial prefrontal cortex and dorsal hippocampus using in vivo microdialysis. The 5-HT(2A/2C) agonist +/-1-(2,5-dimethoxy-4-iodophenyl) -2- aminopropane hydrochloride (DOI) (1 and 2 mg/kg, i.p.) significantly increased the extracellular concentration of ACh in both brain regions, and this response was attenuated in rats treated with the 5-HT(2A/2B/2C) antagonist LY-53,857 (3 mg/kg, i.p.). Treatment with LY-53,857 alone did not significantly alter ACh release in either brain region The 5-HT(2C) agonist 6-chloro-2-(1-piperazinyl)-pyrazine) (MK-212) (5 mg/kg, i.p.) significantly enhanced the release of ACh in both the prefrontal cortex and hippocampus, whereas the 5-HT2 agonist mescaline (10 mg/kg, i.p.) produced a 2-fold increase in ACh release only in the prefrontal cortex. Intracortical, but not intrahippocampal, infusion of DOI (100 microM) significantly enhanced the release of ACh, and intracortical infusion of LY-53,857 (100 microM) significantly attenuated this response. These results suggest that the release of ACh in the prefrontal cortex and hippocampus is influenced by 5-HT2 receptor mechanisms. The increase in release of ACh induced by DOI in the prefrontal cortex, but not in the hippocampus, appears to be due to 5-HT2 receptor mechanisms localized within this brain region. Furthermore, it appears that the prefrontal cortex is more sensitive than the dorsal hippocampus to the stimulatory effect of 5-HT2 agonists on ACh release.     

Ampakine CX546 increases proliferation and neuronal differentiation in subventricular zone stem/progenitor cell cultures

Ampakines are chemical compounds known to modulate the properties of ionotropic α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA)-subtype glutamate receptors. The functional effects attributed to ampakines involve plasticity and the increase in synaptic efficiency of neuronal circuits, a process that may be intimately associated with differentiation of newborn neurons. The subventricular zone (SVZ) is the main neurogenic niche of the brain, containing neural stem cells with brain repair potential. Accordingly, the identification of new pharmaceutical compounds with neurogenesis-enhancing properties is important as a tool to promote neuronal replacement based on the use of SVZ cells. The purpose of the present paper is to examine the possible proneurogenic effects of ampakine CX546 in cell cultures derived from the SVZ of early postnatal mice. We observed that CX546 (50 μm) treatment triggered an increase in proliferation, evaluated by BrdU incorporation assay, in the neuroblast lineage. Moreover, by using a cell viability assay (TUNEL) we found that, in contrast to AMPA, CX546 did not cause cell death. Also, both AMPA and CX546 stimulated neuronal differentiation as evaluated morphologically through neuronal nuclear protein (NeuN) immunocytochemistry and functionally by single-cell calcium imaging. Accordingly, short exposure to CX546 increased axonogenesis, as determined by the number and length of tau-positive axons co-labelled for the phosphorylated form of SAPK/JNK (P-JNK), and dendritogenesis (MAP2-positive neurites). Altogether, this study shows that ampakine CX546 promotes neurogenesis in SVZ cell cultures and thereby may have potential for future stem cell-based therapies.     

GM-CSF and M-CSF modulate beta-chemokine and HIV-1 expression in microglia

Significant numbers of patients with acquired immunodeficiency syndrome (AIDS) develop CNS infection primarily in macrophages and microglial cells. Therefore, the regulation of human immunodeficiency virus type 1 (HIV-1) infection and activation of the brain mononuclear phagocytes subsequent to infection are important areas of investigation. In the current report, we studied the role of granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage-CSF (M-CSF) in the expression of antiviral beta-chemokines and HIV-1 p24 in cultures of primary human fetal microglia. We found that stimulation with GM-CSF or M-CSF induced macrophage inflammatory proteins (MIP-1alpha and MIP-1beta) and augmented RANTES expression, after HIV-1 infection of microglia. This was not due to the effect of GM-CSF on viral expression because GM-CSF was neither necessary nor stimulatory for viral infection, nor did GM-CSF enhance the expression of env-pseudotyped reporter viruses. Blocking GM-CSF-induced microglial proliferation by nocodazole had no effect on beta-chemokine or p24 expression. The functional significance of the GM-CSF-induced beta-chemokines was suggested by the finding that, in the presence of GM-CSF, exogenous beta-chemokines lost their anti-HIV-1 effects. We further show that although HIV-1-infected microglia produced M-CSF, they failed to produce GM-CSF. In vivo, GM-CSF expression was localized to activated astrocytes and some inflammatory cells in HIV-1 encephalitis, suggesting paracrine activation of microglia through GM-CSF. Our results demonstrate a complex interplay between CSFs, chemokines, and virus in microglial cells and may have bearing on the interpretation of data derived in vivo and in vitro.     

Dopamine D4 receptors modulate brain metabolic activity in the prefrontal cortex and cerebellum at rest and in response to methylphenidate

Methylphenidate (MP) is widely used to treat attention deficit hyperactivity disorder (ADHD). Variable number of tandem repeats polymorphisms in the dopamine D4 receptor (D₄) gene have been implicated in vulnerability to ADHD and the response to MP. Here we examined the contribution of dopamine D4 receptors (D4Rs) to baseline brain glucose metabolism and to the regional metabolic responses to MP. We compared brain glucose metabolism (measured with micro‐positron emission tomography and [¹⁸F]2‐fluoro‐2‐deoxy‐d ‐glucose) at baseline and after MP (10 mg/kg, i.p.) administration in mice with genetic deletion of the D₄. Images were analyzed using a novel automated image registration procedure. Baseline D₄^?/? mice had lower metabolism in the prefrontal cortex (PFC) and greater metabolism in the cerebellar vermis (CBV) than D₄^+/+ and D₄^+/? mice; when given MP, D₄^?/? mice increased metabolism in the PFC and decreased it in the CBV, whereas in D₄^+/+ and D₄^+/? mice, MP decreased metabolism in the PFC and increased it in the CBV. These findings provide evidence that D4Rs modulate not only the PFC, which may reflect the activation by dopamine of D4Rs located in this region, but also the CBV, which may reflect an indirect modulation as D4Rs are minimally expressed in this region. As individuals with ADHD show structural and/or functional abnormalities in these brain regions, the association of ADHD with D4Rs may reflect its modulation of these brain regions. The differential response to MP as a function of genotype could explain differences in brain functional responses to MP between patients with ADHD and healthy controls and between patients with ADHD with different D₄ polymorphisms.     

Kampo therapy as an alternative to pharmacotherapy using antipsychotic medicines for behavioral and psychological symptoms of dementia (BPSD)

The behavioral and psychological symptoms of dementia (BPSD), including aggression, agitation, screaming, wandering, hallucinations, and delusions, occur in 50–90% of patients with dementia, and have a negative impact on the activity of daily living (ADL) of patients, as well as caregivers. Patients with severe BPSD often require management with antipsychotic medicines. However, an increased mortality rate has been reported in patients with dementia taking antipsychotic medicine and, thus, there is an urgent need to develop safer treatments for BPSD. Kampo medicines are an alternative to antipsychotic medicines and several Kampo medicines have been reported to be effective in the treatment of BPSD. Oren‐gedoku‐to has been reported to be effective for the treatment of irritability and sullenness in patients with vascular dementia, as well as improving excitement, depression, anxiety, and restlessness of patients with cerebrovascular lesions. Choto‐san has been reported to be effective in the treatment of delirium, insomnia, and hallucinations/delusions in patients with vascular dementia. Toki‐syakuyaku‐san has been reported to improve emotional lability, restlessness, and sleep disturbances in patients with dementia. Yokukan‐san has been reported to be effective for hallucinations, agitation/aggression, irritability/lability, and aberrant motor activity, as well as being effective in the treatment of visual hallucinations in patients with dementia with Lewy bodies (DLB). A multicenter randomized crossover study confirmed that Yokukan‐san is effective in the treatment of BPSD and is well‐tolerated. Kampo medicines do not induce extrapyramidal or anticholinergic symptoms and have no adverse effects on ADL or cognitive function. Thus, Kampo therapy is recommended for patients who cannot tolerate treatment with neuroleptics, patients who have extrapyramidal symptoms and gait disturbance, and patients with DLB. In future, to confirm the effectiveness of Kampo medicines in the treatment of BPSD, further studies, such as randomized control trials, are needed. In addition, basic studies are required to elucidate the processes by which Kampo medicines are metabolized, as well as any interactions between Western and Kampo medicines.     

Organisation and maturation of the human thalamus as revealed by CD15

The distribution of the CD15 antigen (CD15, 3-fucosyl-N-acetyl-lactosamine, Lewis x) has been studied immunohistochemically in the fetal human thalamus. Its changing patterns could be related to three successive, but overlapping, periods primarily due to its association with radial glial cells, neuropil, and neural cell bodies, respectively. From 9 weeks of gestation (wg), a subset of CD15-positive radial glial cells distinguished the neuroepithelium of the ventral thalamus, a characteristic also seen in the developing mouse. Distal processes of the radial glial cells converged at the root of the forebrain choroid tenia, which was also CD15 positive. From 13 wg until approximately 20 wg, CD15-positive neuropil labeling marked the differentiation areas of prospective nuclei within the dorsal thalamus and progressively outlined their territories in a time sequence, which appeared specific for each nucleus. CD15 labeling of differentiating nuclei of the ventral, medial, anterior, and intralaminar thalamic divisions showed a transient topographic relationship with restricted areas of the ventricular wall. After 26 wg, CD15 immunoreactivity was observed in subpopulations of glial cells and neurons. Transient CD15 immunoreactivity was also found in delimited compartments within the subventricular region. The time of CD15 expression, its location, and cellular association suggest that CD15 is involved in segmentation of diencephalon, in the specification of differentiating nuclear areas and initial processes regarding the formation of intercellular contacts and cellular maturation.     

Functional connectivity between posterior hippocampus and retrosplenial complex predicts individual differences in navigational ability

Individuals vary widely in their ability to orient and navigate within the environment. Previous neuroimaging research has shown that hippocampus (HC) and scene‐responsive regions (retrosplenial complex [RSC] and parahippocampal gyrus/parahippocampal place area [PPA]) were crucial for spatial orienting and navigation. Resting‐state functional connectivity and a self‐reported questionnaire of navigational ability were used to examine the hypothesis that the pattern of reciprocal connections between these regions reflects individual differences in spatial navigation. It was found that the functional connectivity between the posterior HC and RSC was significantly higher in good than in poor navigators. These results confirmed the crucial role of hippocampal and extra‐hippocampal regions in spatial navigation and provided new insight into how spontaneous brain activity may account for individual differences in spatial ability. © 2016 Wiley Periodicals, Inc.     

The comparison of mouse full metallothionein‐1 versus α and β domains and metallothionein‐1‐to‐3 mutation following traumatic brain injury reveals different biological motifs

Traumatic injury to the brain is one of the leading causes of injury‐related death or disability, but current therapies are limited. Previously it has been shown that the antioxidant proteins metallothioneins (MTs) are potent neuroprotective factors in animal models of brain injury. The exogenous administration of MTs causes effects consistent with the roles proposed from studies in knock‐out mice. We herewith report the results comparing full mouse MT‐1 with the independent α and β domains, alone or together, in a cryoinjury model. The lesion of the cortex caused the mice to perform worse in the horizontal ladder beam and the rota‐rod tests; all the proteins showed a modest effect in the former test, while only full MT‐1 improved the performance of animals in the rota‐rod, and the α domain showed a rather detrimental effect. Gene expression analysis by RNA protection assay demonstrated that all proteins may alter the expression of host‐response genes such as GFAP, Mac1 and ICAM, in some cases being the β domain more effective than the α domain or even the full MT‐1. A MT‐1‐to‐MT‐3 mutation blunted some but not all the effects caused by the normal MT‐1, and in some cases increased its potency. Thus, splitting the two MT‐1 domains do not seem to eliminate all MT functions but certainly modifies them, and different motifs seem to be present in the protein underlying such functions. © 2010 Wiley‐Liss, Inc.     

Clinical and sociodemographic comparison of people at high‐risk for psychosis and with first‐episode psychosis

Zimbrón J, Ruiz de Azúa S, Khandaker GM, Gandamaneni PK, Crane CM, González‐Pinto A, Stochl J, Jones PB, Pérez J. Clinical and sociodemographic comparison of people at high‐risk for psychosis and with first‐episode psychosis. Objective: To compare clinical and sociodemographic characteristics previously associated with psychosis, between individuals at high‐risk for psychosis (HR) and patients experiencing a first episode psychosis (FEP), to achieve a better understanding of factors associated with psychosis. Method: Cross‐sectional comparison of 30 individuals at HR with 30 age‐gender matched FEP, presenting to an early intervention service for psychosis. Participants were followed‐up for 2 years to establish the proportion of HR who made the transition into FEP. Results: Both groups showed similar socio‐clinical characteristics, including immigration status, employment history, marital status, family history of psychotic illness, self‐harm and alcohol and drug use. The HR group had a lower level of education, higher burden of trauma, earlier onset of psychiatric symptoms and a longer delay in accessing specialised services. A younger onset of symptoms was associated with a longer delay in accessing services in both groups. After a 2 year follow‐up, only three (10%) of the HR group made a transition into FEP. Conclusion: The similarities observed between individuals at HR and those with FEP suggest that known variables associated with psychosis may be equally prevalent in people at HR who do not develop a psychotic disorder.     

Service contact and psychopathology in very-late-onset schizophrenia-like psychosis: the effects of gender and ethnicity

BACKGROUND: Epidemiological data on very-late-onset (>60 years) schizophrenia-like psychosis (SLP) are scarce. There are only two published follow-up studies. OBJECTIVE: To examine the associations of gender and ethnicity with health service contact and psychopathology in SLP. METHOD: We identified all new referrals of SLP to the Maudsley hospital between 1995-2000. Demographic details and information on the course of the illness were obtained from case notes. Those patients who agreed to take part were seen at home and assessed with respect to psychopathology and neurological side effects. RESULTS: The median duration of illness at the time of assessment was 3 years (range 1-6 years). Male patients were more likely to be admitted to hospital compulsorily and to be lost to follow-up than female patients. Caribbean-born patients were more likely to refuse to take part than British-born patients. Of the 26 (48%) patients who were interviewed, 38% were experiencing paranoid symptoms, 94% of patients receiving medication were in regular contact with a community psychiatric nurse (CPN). Treatment response was dose related and was not increased by the use of a depot. CONCLUSION: The effects of gender and ethnicity on outcome need to be further investigated through larger studies. High loss to follow-up amongst male patients may be indicative of a poor prognosis. Regular contact with a CPN may be more important than the use of a depot in maintaining treatment response.     

Perampanel in patients with refractory and super‐refractory status epilepticus in a neurological intensive care unit: A single‐center audit of 30 patients

In refractory status epilepticus (SE), γ‐aminobutyric acidergic drugs become less effective and glutamate plays a major role in seizure perpetuation. Data on the efficacy of perampanel (PER) in treatment of refractory SE in humans are limited. Here, we present a single‐center case series of patients with refractory SE who received PER orally in an intensive care unit. We retrospectively analyzed treatment response, outcome, and adverse effects of all patients with refractory SE in our Neurological Intensive Care Unit who received add‐on PER between September 2012 and February 2018. Thirty patients with refractory SE (median = 72 years, range = 18‐91, 77% women) were included. In 14 patients (47%), a high‐dose approach was used, with a median initial dose of 24 mg (range = 16‐32). In five patients (17%), SE could be terminated after PER administration (median dose = 6 mg, range = 6‐20 mg, 2/5 patients in high‐dose group). Clinical response was observed after a median of 24 hours (range = 8‐48 hours), whereas electroencephalogram resolved after a median of 60 hours (range = 12‐72 hours). Time to treatment response tended to be shorter in patients receiving high‐dose PER (median clinical response = 16 hours vs 18 hours; electroencephalographic response = 24 hours vs 72 hours), but groups were too small for statistical analysis. Continuous cardiorespiratory monitoring showed no changes in cardiorespiratory function after “standard” and “high‐dose” treatment. Elevated liver enzymes without clinical symptoms were observed after a median of 6 days in seven of 30 patients (23%; 57% high dose vs 43% standard dose), of whom six also received treatment with phenytoin (PHT). Outcome was unfavorable (death, persistent vegetative state) in 13 patients (43%; 39% high dose vs 61% standard dose), and good recovery (no significant disability, moderate disability) was achieved in nine patients (56% high dose vs 44% standard dose). Oral PER in loading doses up to 32 mg were well tolerated but could terminate SE only in a few patients (5/30; 17%). Long duration of SE, route of administration, and severe underlying brain dysfunction might be responsible for the modest result. An intravenous formulation is highly desired to explore the full clinical utility in the treatment of refractory SE.     

Neuroprotective effects and mechanisms of exercise in a chronic mouse model of Parkinson's disease with moderate neurodegeneration

The protective impact of exercise on neurodegenerative processes has not been confirmed, and the mechanisms underlying the benefit of exercise have not been determined in human Parkinson's disease or in chronic animal disease models. This research examined the long-term neurological, behavioral, and mechanistic consequences of endurance exercise in experimental chronic parkinsonism. We used a chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of Parkinson's disease with moderate neurodegeneration and examined the effects of treadmill exercise on movement and balance coordination, changes in dopamine neuron biomarkers, mitochondrial functions, and neurotrophic factor activities in the nigrostriatal system. The exercise results were compared with those of the control and sedentary chronic parkinsonian animals. After 18 weeks of exercise training in the chronic parkinsonian mice, we observed a significant deterrence in the loss of neuronal dopamine-producing cells and other functional indicators. The impaired movement and balance incoordination in the chronic parkinsonian mice were also markedly reduced following exercise. Mechanistic investigations revealed that the neuronal and behavioral recovery produced by exercise in the chronic parkinsonian mice was associated with an improved mitochondrial function and an increase in the brain region-specific levels of brain-derived and glial cell line-derived neurotrophic factors. Our findings indicate that exercise not only produces neuronal and mitochondrial protection, it also boosts nigrostriatal neurotrophic factor levels in the chronic parkinsonian mice with moderate neurodegeneration. Therefore, modifying lifestyle with increased exercise activity would be a non-pharmacological neuroprotective approach for averting neurodegenerative processes, as demonstrated in experimental chronic parkinsonism.     

Acute and chronic effects of citalopram on 5‐HT1A receptor—Labeling by [18F]MPPF and—Coupling to receptors‐G proteins

Selective serotonin reuptake inhibitors take several weeks to produce their maximal therapeutic antidepressant effect. This delay has been attributed to the gradual desensitization of somatodendritic serotonin 5‐HT_1A autoreceptors. We evaluated adaptive changes of 5‐HT_1A receptors after acute and chronic citalopram challenges in rat. Small animal positron emission tomography trial and quantitative ex vivo autoradiography studies using [¹⁸F]MPPF were employed, as well as in vitro 8‐OH‐DPAT‐stimulated [³⁵S]‐GTPγS binding assay. Additionally, 5‐HT_1A receptor knock‐out mice were used to assess the specificity of [¹⁸F]MPPF. Acute treatment with citalopram did not alter [¹⁸F]MPPF binding in dorsal raphe nucleus (DR), frontal cortex, or hippocampus. The absence of [¹⁸F]MPPF binding in the brain of 5‐HT_1A knock‐out mice demonstrates the specificity of MPPF for 5‐HT_1A receptor brain imaging, but the high affinity of [¹⁸F]MPPF compared to 5‐HT suggests that it would only be displaced by dramatic increases in extracellular 5‐HT. Chronic citalopram did not modify 5‐HT_1A receptor density in any of the brain regions studied. In addition, this treatment did not modify 8‐OH‐DPAT‐stimulated [³⁵S]‐GTPγS binding in DR, although a significant increase was observed in frontal cortex and hippocampus. [¹⁸F]MPPF appears to be an efficient radioligand to quantify specifically 5‐HT_1A receptor density in brain imaging. The delayed therapeutic efficacy of citalopram did not appear to be linked to either a downregulation of 5‐HT_1A receptors or to a 5‐HT_1A receptor‐G protein decoupling process in serotonergic neurons, but to increased functional sensitivity of postsynaptic 5‐HT_1A receptors. Synapse 63:106–116, 2009. ©2008 Wiley‐Liss, Inc.     

Markers of inflammation and cognitive decline in an African-Caribbean population

BACKGROUND: Inflammatory processes may play an important role in cognitive decline and dementia. We investigated the prospective association between levels of three markers of inflammation, plasma interleukin-6 (IL-6), serum C-reactive protein (CRP), serum amyloid A (SAA), and cognitive decline in an African-Caribbean community population. METHODS: Of 290 participants aged 55-75 years at baseline sampled from Primary Care registration lists in south London, 216 (75%) were re-interviewed after 3 years. Baseline plasma concentrations of IL-6, CRP and SAA were ascertained through immunoassays. A battery of psychometric tests was administered on both occasions and decline in both individual tests and a composite outcome was analysed. RESULTS: After adjustment for potential confounding factors, raised levels of IL-6 (>3.1 pg/ml) were associated with cognitive decline in the total sample (odds ratio 2.9, 95% CI 1.1-7.5), but no associations were found for CRP or SAA. Raised IL-6 was most strongly associated with decline in orientation and immediate verbal recall tasks, with weaker associations for delayed recall and psychomotor speed. CONCLUSIONS: Raised IL-6 but not CRP predicted cognitive decline in this population Inflammatory changes associated with cognitive decline may be specific to particular causal pathways.