Alteration in Nuclear Factor-KappaB Pathway and Functionality of Estrogen via Receptors Promote Neuroinflammation in Frontal Cortex after 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine Treatment

The Gender-Specific Interaction of DVL3 and GSK3β Polymorphisms on Major Depressive Disorder Susceptibility in a Chinese Han Population: A Case-Control Study

Based on the “oxidative stress hypothesis” of major depressive disorder (MDD), cells regulate their structure through the Wnt pathway. Little is known regarding the interactions of dishevelled 3 (DVL3) and glycogen synthase kinase 3 beta (GSK3β) polymorphisms with MDD. The aim of the current study was to verify the relationship between DVL3 and GSK3β genetic variants in a Chinese Han population and further to evaluate whether these interactions exhibit gender-specificity. A total of 1136 participants, consisting of 541 MDD patients and 595 healthy subjects, were recruited. Five single-nucleotide polymorphisms (SNPs) of DVL3/GSK3β were selected to assess their interaction by use of a generalized multifactor dimensionality reduction method. The genotype and haplotype frequencies of DVL3/GSK3β polymorphisms were significantly different between patients and controls for DVL3 rs1709642 ( $P<0.01$ ) and GSK3β rs334558, rs6438552, and rs2199503 ( $P<0.01$ ). In addition, our results also showed that there were significant interaction effects between DVL3 and GSK3β polymorphisms and the risk of developing MDD, particularly in women. The interaction between DVL3 (rs1709642) and GSK3β (rs334558, rs6438552) showed a cross-validation (CV) consistency of 10/10, a $P$ value of 0.001, and a testing accuracy of 59.22%, which was considered as the best generalized multifactor dimensionality reduction (GMDR) model. This study reveals the interaction between DVL3 and GSK3β polymorphisms on MDD susceptibility in a female Chinese Han population. The effect of gender should be taken into account in future studies that seek to explore the genetic predisposition to MDD relative to the DVL3 and GSK3β genes.

Sex and Pubertal Status Influence Dendritic Spine Density on Frontal Corticostriatal Projection Neurons in Mice

In humans, nonhuman primates, and rodents, the frontal cortices exhibit grey matter thinning and dendritic spine pruning that extends into adolescence. This maturation is believed to support higher cognition but may also confer psychiatric vulnerability during adolescence. Currently, little is known about how specific cell types in the frontal cortex mature or whether puberty plays a role in the maturation of some cell types but not others. Here, we used mice to characterize the spatial topography and adolescent development of cross-corticostriatal (cSTR) neurons that project through the corpus collosum to the dorsomedial striatum. We found that apical spine density on cSTR neurons in the medial prefrontal cortex decreased significantly between late juvenile (P29) and young adult time points (P60), with females exhibiting higher spine density than males at both ages. Adult males castrated prior to puberty onset had higher spine density compared to sham controls. Adult females ovariectomized before puberty onset showed greater variance in spine density measures on cSTR cells compared to controls, but their mean spine density did not significantly differ from sham controls. Our findings reveal that these cSTR neurons, a subtype of the broader class of intratelencephalic-type neurons, exhibit significant sex differences and suggest that spine pruning on cSTR neurons is regulated by puberty in male mice.

2-(5-(4-Chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazol-3-yl)-N-(2-hydroxyethyl)-2-oxoacetamide (CDMPO) has anti-inflammatory properties in microglial cells and prevents neuronal and behavioral deficits in MPTP mouse model of Parkinson's disease

Parkinson's disease (PD) is characterized by the selective loss of nigrostriatal dopamine neurons associated with microglial activation. Inhibition of the inflammatory response elicited by activated microglia could be an effective strategy to alleviate the progression of PD. Here, we synthesized 2-(5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazol-3-yl)-N-(2-hydroxyethyl)-2-oxoacetamide (CDMPO) and studied its protective anti-inflammatory mechanisms following lipopolysaccharide (LPS)-induced neuroinflammation in vitro and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in vivo. CDMPO and its parent compound, rimonabant, significantly attenuated nitric oxide (NO) production in LPS-stimulated primary microglia and BV2 cells. Furthermore, CDMPO significantly inhibited the release of proinflammatory cytokines and prostaglandin E2 (PGE₂) by activated BV2 cells, also suppressed expression of inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). Mechanistically, CDMPO attenuated LPS-induced activation of nuclear factor-kappa B (NF-κB), inhibitor of kappa B alpha (IκBα), and p38 phosphorylation in BV2 cells. MPTP intoxication of mice results in glial activation, tyrosine hydroxylase (TH) depletion, and significant behavioral deficits. Prophylactic treatment with CDMPO decreased proinflammatory molecules via NF-κB and p38 mitogen-activated protein kinase signaling, resulting in protection of dopaminergic neurons and improved behavioral impairments. These results suggest that CDMPO is a promising neuroprotective agent for the prevention and treatment of microglia-mediated neuroinflammatory conditions and may be useful for behavioral improvement in PD phenotype.

Molecular mechanisms involved in the protective actions of Selective Estrogen Receptor Modulators in brain cells

Synthetic selective modulators of the estrogen receptors (SERMs) have shown to protect neurons and glial cells against toxic insults. Among the most relevant beneficial effects attributed to these compounds are the regulation of inflammation, attenuation of astrogliosis and microglial activation, prevention of excitotoxicity and as a consequence the reduction of neuronal cell death. Under pathological conditions, the mechanism of action of the SERMs involves the activation of estrogen receptors (ERs) and G protein-coupled receptor for estrogens (GRP30). These receptors trigger neuroprotective responses such as increasing the expression of antioxidants and the activation of kinase-mediated survival signaling pathways. Despite the advances in the knowledge of the pathways activated by the SERMs, their mechanism of action is still not entirely clear, and there are several controversies. In this review, we focused on the molecular pathways activated by SERMs in brain cells, mainly astrocytes, as a response to treatment with raloxifene and tamoxifen.

The transcriptional regulation of an antimicrobial peptide hepcidin1 in Oryzias melastigma upon EE2 exposure involved in a new pathway with a novel transcriptional regulatory element HepERE

17α-ethinylestradiol (EE2) exerts endocrine disrupting effect and immunotoxic effect on marine animals, including modulation of hepcidin expression. The antimicrobial peptide hepcidin displays a crucial role in innate immunity in fish against invading pathogens. It is known that the transcription of hepcidin in mammals is individually regulated by many stimuli, including inflammation, iron overload, anemia or hypoxia, through several distinct molecular pathways. The canonical mechanism for endocrine disrupting effects is mediated by an estrogen receptor (ER) and estrogen responsive element (ERE), whereas the underlying mechanism for immunotoxic effect is still unclear. In this study, a hepcidin from Oryzias melastigma (OM-hep1) was found to be down-regulated upon EE2 exposure and was associated with ERα. Unlike the revealed signaling pathways for hepcidin regulation in mammals, it was revealed by promoter activity analysis that the OM-hep1 transcription was not associated with canonical immune-associated and hormone-associated regulatory elements, known as the nuclear factor κB (NF-κB), signal transducer and activator of transcription 3 (STAT3), ERE and estrogen-related receptor responsive element (ERRE). Further analysis through a series of base mutations revealed a short fragment from -315 to -289 bp on the OM-hep1 promoter with high activity. This fragment was composed of a putative ERE-like element (23 bases) plus an adjacent down-streamed four bases motif GTGT. Replacement of either of the core bases (GGTCA) of ERE-like or GTGT motif showed non-activity and non-response to EE2 exposure, thus a new hepcidin-associated element named as HepERE was revealed. Evidences from electrophoretic mobility shift assay (EMSA) and surface plasmon resonance (SPR) assay demonstrated that the EE2-mediated down-regulation of OM-hep1 expression was associated with ERα binding to HepERE but not classical ERE. Taken together, a novel signaling pathway was revealed and the regulatory mechanism associated with the ERα and HepERE element on immunomodulation of OM-hep1 expression upon EE2 exposure was first reported here.

TNFR2 mediated TNF-α signaling and NF-κB activation in hippocampus of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice

1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine (MPTP) -induced neuroinflammation and its impact in hippocampus remain elusive till date. Our present study includes the time dependent changes of inflammatory molecules in mouse hippocampus during MPTP treatment. MPTP treatment increased level of TNF-α, enhanced expression of TNFR2 along with PI3 kinase (PI3K) induced phosphorylation of Akt resulting in persistent nuclear factor-κB (NF-κB) activation. The expressions gradually increased from Day1 post-MPTP treatment, maximally at Day3 post-treatment. MPTP induced translocation of p65 and p52, two subunits of NF-κB family, to nucleus where they had been found to dimerize. Therefore, MPTP induced TNF-α signaling through TNFR2 mediated pathway and recruited p65-p52 dimer in hippocampal nucleus which is reported to have protective effect on hippocampal neurons indicated by unchanged neuronal count in hippocampus in treated groups with respect to control. Our finding suggests that this unique NF-κB dimer plays some role in providing inherent protection to hippocampus during MPTP-treatment.

Does puberty mark a transition in sensitive periods for plasticity in the associative neocortex?

Postnatal brain development is studded with sensitive periods during which experience dependent plasticity is enhanced. This enables rapid learning from environmental inputs and reorganization of cortical circuits that matches behavior with environmental contingencies. Significant headway has been achieved in characterizing and understanding sensitive period biology in primary sensory cortices, but relatively little is known about sensitive period biology in associative neocortex. One possible mediator is the onset of puberty, which marks the transition to adolescence, when animals shift their behavior toward gaining independence and exploring their social world. Puberty onset correlates with reduced behavioral plasticity in some domains and enhanced plasticity in others, and therefore may drive the transition from juvenile to adolescent brain function. Pubertal onset is also occurring earlier in developed nations, particularly in unserved populations, and earlier puberty is associated with vulnerability for substance use, depression and anxiety. In the present article we review the evidence that supports a causal role for puberty in developmental changes in the function and neurobiology of the associative neocortex. We also propose a model for how pubertal hormones may regulate sensitive period plasticity in associative neocortex. We conclude that the evidence suggests puberty onset may play a causal role in some aspects of associative neocortical development, but that further research that manipulates puberty and measures gonadal hormones is required. We argue that further work of this kind is urgently needed to determine how earlier puberty may negatively impact human health and learning potential. This article is part of a Special Issue entitled SI: Adolescent plasticity.