Adult conditional knockout of PGC-1α in GABAergic neurons causes exaggerated startle reactivity, impaired short-term habituation and hyperactivity

Study on the role of Dihuang Yinzi in regulating the AMPK/SIRT1/PGC-1α pathway to promote mitochondrial biogenesis and improve Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Dihuang Yinzi (DHYZ) is a classic prescription in traditional Chinese medicine. Its therapeutic effect on Alzheimer's disease (AD) has been widely validated. However, the underlying molecular mechanisms of DHYZ in AD treatment remain unclear and require further research.

AIM OF THE STUDY

Elucidating DHYZ's promotion of mitochondrial biogenesis through the AMPK/SIRT1/PGC-1α pathway improves neuronal loss, mitochondrial damage, and memory deficits in AD.

MATERIALS AND METHODS

Administering DHYZ by gavage to SAMP8 mice, after completing behavioral tests, the effects of DHYZ on hippocampal neuron loss and mitochondrial structural damage in AD model mice were assessed using Nissl staining and transmission electron microscopy. Western blot was used to detect the expression of mitochondrial biogenesis-related proteins PGC-1α, CREB, mitochondrial fusion protein MFN2, and mitochondrial fission proteins DRP1 and FIS1. At the same time, immunofluorescence (IF) was employed to measure the relative fluorescence intensity of mitochondrial fusion protein MFN1. After determining the optimal dose of DYHZ for treating AD, we conducted mechanistic studies. By intraperitoneally injecting SAMP8 mice with the AMPK inhibitor (Compound C) to inhibit AMPK protein expression and subsequently treating them with DHYZ, the impact of DHYZ on hippocampal neurons in AD model mice was evaluated using Nissl and hematoxylin-eosin staining. Western blot was used to detect the protein expression of AMPK, p-AMPK, SIRT1, PGC-1α, NRF1, and TFAM. In contrast, IF was used to measure the relative fluorescence intensity of PGC-1α, NRF1, and TFAM proteins in the hippocampal CA1 region.

RESULTS

DHYZ significantly improved AD model mice's cognitive impairment and memory deficits and mitigated hippocampal neuron loss and degeneration. Additionally, it ameliorated mitochondrial morphological structures. DHYZ upregulated the protein expression of mitochondrial biogenesis-related proteins PGC-1α, CREB, and mitochondrial fusion proteins MFN1 and MFN2 while inhibiting the expression of mitochondrial fission proteins DRP1 and FIS1. Further studies revealed that DHYZ could upregulate the expression of the AMPK/SIRT1/PGC-1α pathway proteins and their downstream proteins NRF1 and TFAM.

CONCLUSION

DHYZ promotes mitochondrial biogenesis by activating the AMPK/SIRT1/PGC-1α signaling pathway, thereby improving memory deficits, neuronal loss, and mitochondrial dysfunction in AD.

Micro-Infusion of 5-HT1a Receptor Antagonists into the Ventral Subiculum Ameliorate MK-801 Induced Schizophrenia-Like Behavior in Rats

Recent studies have shown that the 5-HT1a receptor (5-HT1aR) in the central 5-HT (Serotonergic) system is involved in the pathophysiology of schizophrenia through its various receptors, and the dysfunction of the ventral hippocampus may be a key causative factor in schizophrenia. To date, whether the 5-HT1a receptor is involved in ventral hippocampal dysfunction and its internal mechanism remain unclear. In this study, schizophrenia-like animal model was induced by intraperitoneal injection of aspartate receptor antagonist MK-801 in male Sprague Dawley rats, and the role of 5-HT1aR in this animal model was investigated by bilaterally micro-infusing the 5-HT1aR antagonist WAY100635 into the ventral subiculum (vSub) of the hippocampus of rats. Behavioral experiments such as open field test (OFT) and prepulse inhibition (PPI) were performed. The results showed that MK-801 induced hyperactivity and impaired prepulse inhibition in rats, whereas, micro-infusion of 5-HT1aR antagonist WAY100635 into the vSub ameliorated these phenomena. Immunofluorescence analysis revealed that WAY100635 significantly increased the c-Fos expression in vSub. Western blot and immunohistochemical analysis showed that MK-801 induced up-regulation of 5-HT1aR and phospho-extracellular regulated protein kinase (p-ERK) pathway, while micro-infusion of the WAY100635 down-regulated 5-HT1aR and p-ERK in the vSub. Therefore, the results of the present study suggested that in vSub, the 5-HT1aR antagonist WAY100635 may attenuate MK-801-induced schizophrenia-like activity by modulating excitatory neurons and downregulating p-ERK.

FoxG1 as a Potential Therapeutic Target for Alzheimer's Disease: Modulating NLRP3 Inflammasome via AMPK/mTOR Autophagy Pathway

An increasing body of research suggests that promoting microglial autophagy hinders the neuroinflammation initiated though the NLRP3 inflammasome activation in Alzheimer's disease (AD). The function of FoxG1, a crucial transcription factor involved in cell survival by regulating mitochondrial function, remains unknown during the AD process and neuroinflammation occurs. In the present study, we firstly found that Aβ peptides induced AD-like neuroinflammation upregulation and downregulated the level of autophagy. Following low-dose Aβ25-35 stimulation, FoxG1 expression and autophagy exhibited a gradual increase. Nevertheless, with high-concentration Aβ25-35 treatment, progressive decrease in FoxG1 expression and autophagy levels as the concentration of Aβ25-35 escalated. In addition, FoxG1 has a positive effect on cell viability and autophagy in the nervous system. In parallel with the Aβ25-35 stimulation, we employed siRNA to decrease the expression of FoxG1 in N2A cells. A substantial reduction in autophagy level (Beclin1, LC3II, SQSTM1/P62) and a notable growth in inflammatory response (NLRP3, TNF-α, and IL-6) were observed. In addition, we found FoxG1 overexpression owned the effect on the activation of AMPK/mTOR autophagy pathway and siRNA-FoxG1 successfully abolished this effect. Lastly, FoxG1 suppressed the NLRP3 inflammasome and enhanced the cognitive function in AD-like mouse model induced by Aβ25-35. Confirmed by cellular and animal experiments, FoxG1 suppressed NLRP3-mediated neuroinflammation, which was strongly linked to autophagy regulated by AMPK/mTOR. Taken together, FoxG1 may be a critical node in the pathologic progression of AD and has the potential to serve as therapeutic target.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family in physiological and pathophysiological process and diseases

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family (PGC-1s), consisting of three members encompassing PGC-1α, PGC-1β, and PGC-1-related coactivator (PRC), was discovered more than a quarter-century ago. PGC-1s are essential coordinators of many vital cellular events, including mitochondrial functions, oxidative stress, endoplasmic reticulum homeostasis, and inflammation. Accumulating evidence has shown that PGC-1s are implicated in many diseases, such as cancers, cardiac diseases and cardiovascular diseases, neurological disorders, kidney diseases, motor system diseases, and metabolic disorders. Examining the upstream modulators and co-activated partners of PGC-1s and identifying critical biological events modulated by downstream effectors of PGC-1s contribute to the presentation of the elaborate network of PGC-1s. Furthermore, discussing the correlation between PGC-1s and diseases as well as summarizing the therapy targeting PGC-1s helps make individualized and precise intervention methods. In this review, we summarize basic knowledge regarding the PGC-1s family as well as the molecular regulatory network, discuss the physio-pathological roles of PGC-1s in human diseases, review the application of PGC-1s, including the diagnostic and prognostic value of PGC-1s and several therapies in pre-clinical studies, and suggest several directions for future investigations. This review presents the immense potential of targeting PGC-1s in the treatment of diseases and hopefully facilitates the promotion of PGC-1s as new therapeutic targets.

Prefrontal cortex-specific Dcc deletion induces schizophrenia-related behavioral phenotypes and fail to be rescued by olanzapine treatment

Multiple genome studies have discovered that variation in deleted in colorectal carcinoma (Dcc) at transcription and translation level were associated with the occurrences of psychiatric disorders. Yet, little is known about the function of Dcc in schizophrenia (SCZ)-related behavioral abnormalities and the efficacy of antipsychotic drugs in vivo. Here, we used an animal model of prefrontal cortex-specific knockdown (KD) of Dcc in adult C57BL/6 mice to study the attention deficits and impaired locomotor activity. Our results supported a critical role of Dcc deletion in SCZ-related behaviors. Notably, olanzapine rescued the SCZ-related behaviors in the MK801-treated mice but not in the cortex-specific Dcc KD mice, indicating that Dcc play a critical in the mechanism of antipsychotic effects of olanzapine. Knockdown of Dcc in prefrontal cortex results in glutamatergic dysfunction, including defects in glutamine synthetase and postsynaptic maturation. As one of the major risk factors of the degree of antipsychotic response, Dcc deletion-induced glutamatergic dysfunction may be involved in the underlying mechanism of treatment resistance of olanzapine. Our findings identified Dcc deletion-mediated SCZ-related behavioral defects, which serve as a valuable animal model for study of SCZ and amenable to targeted investigations in mechanistic hypotheses of the mechanism underlying glutamatergic dysfunction-induced antipsychotic treatment resistance.

PGC-1α regulates critical period onset/closure, mediating cortical plasticity

Peroxisome proliferator-activated receptor PPARγ coactivator-α (PGC-1α) is concentrated in inhibitory interneurons and plays a vital role in neuropsychiatric diseases. We previously reported some characteristic features of schizophrenia (SZ) in GABAergic neuron-specific Pgc-1alpha knockout (KO) mice (Dlx5/6-Cre: Pgc-1alphaf/f). However, there is a fundamental gap in the molecular mechanism by which the Pgc-1alpha gene is involved in the neurobehavioral abnormalities of SZ. The loss of critical period (CP) triggers-maturations of parvalbumin interneurons (PVIs) and brakes-and the formation of perineuronal nets (PNNs) implicates mistimed trajectories during adult brain development. In this study, using the Pgc-1alpha KO mouse line, we investigated the association of Pgc-1alpha gene deletion with SZ-like behavioral deficits, PVI maturation, PNN integrity and synaptic ultrastructure. These findings suggest that Pgc-1alpha gene deletion resulted in a failure of CP onset and closure, thereby prolonging cortical plasticity timing. To determine whether the manipulation of the PNN structure is a potential method of altering neuronal plasticity, GM6001, a broad-spectrum matrix metalloproteinase (MMP)-inhibitor was applied. Here we confirmed that the treatment could effectively correct the CP plasticity window and ameliorate the synaptic ultrastructure in the Pgc-1alpha KO brain. Moreover, the intervention effect on neuronal plasticity was followed by the rescue of short-term habituation deficits and the mitigation of aberrant salience, which are some characteristic features of SZ. Taken collectively, these findings suggest that the role of PGC-1α in regulating cortical plasticity is mediated, at least partially, through the regulation of CP onset/closure. Strategically introduced reinforcement of molecular brakes may be a novel preventive therapy for psychiatric disorders associated with PGC-1α dysregulation.

FOXG1 Contributes Adult Hippocampal Neurogenesis in Mice

Strategies to enhance hippocampal precursor cells efficiently differentiate into neurons could be crucial for structural repair after neurodegenerative damage. FOXG1 has been shown to play an important role in pattern formation, cell proliferation, and cell specification during embryonic and early postnatal neurogenesis. Thus far, the role of FOXG1 in adult hippocampal neurogenesis is largely unknown. Utilizing CAG-loxp-stop-loxp-Foxg1-IRES-EGFP (Foxg1^fl/fl), a specific mouse line combined with CreAAV infusion, we successfully forced FOXG1 overexpressed in the hippocampal dentate gyrus (DG) of the genotype mice. Thereafter, we explored the function of FOXG1 on neuronal lineage progression and hippocampal neurogenesis in adult mice. By inhibiting p21^cip1 expression, FOXG1-regulated activities enable the expansion of the precursor cell population. Besides, FOXG1 induced quiescent radial-glia like type I neural progenitor, giving rise to intermediate progenitor cells, neuroblasts in the hippocampal DG. Through increasing the length of G₁ phase, FOXG1 promoted lineage-committed cells to exit the cell cycle and differentiate into mature neurons. The present results suggest that FOXG1 likely promotes neuronal lineage progression and thereby contributes to adult hippocampal neurogenesis. Elevating FOXG1 levels either pharmacologically or through other means could present a therapeutic strategy for disease related with neuronal loss.

Mitochondrial dysfunction in psychiatric disorders

Psychiatric disorders are a heterogeneous group of mental disorders with abnormal mental or behavioral patterns, which severely distress or disable affected individuals and can have a grave socioeconomic burden. Growing evidence indicates that mitochondrial function plays an important role in developing psychiatric disorders. This review discusses the neuropsychiatric consequences of mitochondrial abnormalities in both animal models and patients. We also discuss recent studies associated with compromised mitochondrial function in various psychiatric disorders, such as schizophrenia (SCZ), major depressive disorder (MD), and bipolar disorders (BD). These studies employ various approaches including postmortem studies, imaging studies, genetic studies, and induced pluripotent stem cells (iPSCs) studies. We also summarize the evidence from animal models and clinical trials to support mitochondrial function as a potential therapeutic target to treat various psychiatric disorders. This review will contribute to furthering our understanding of the metabolic etiology of various psychiatric disorders, and help guide the development of optimal therapies.

Genetics, molecular control and clinical relevance of habituation learning

Habituation is the most fundamental form of learning. As a firewall that protects our brain from sensory overload, it is indispensable for cognitive processes. Studies in humans and animal models provide increasing evidence that habituation is affected in autism and related monogenic neurodevelopmental disorders (NDDs). An integrated application of habituation assessment in NDDs and their animal models has unexploited potential for neuroscience and medical care. With the aim to gain mechanistic insights, we systematically retrieved genes that have been demonstrated in the literature to underlie habituation. We identified 258 evolutionarily conserved genes across species, describe the biological processes they converge on, and highlight regulatory pathways and drugs that may alleviate habituation deficits. We also summarize current habituation paradigms and extract the most decisive arguments that support the crucial role of habituation for cognition in health and disease. We conclude that habituation is a conserved, quantitative, cognition- and disease-relevant process that can connect preclinical and clinical work, and hence is a powerful tool to advance research, diagnostics, and treatment of NDDs.

A Role for PGC-1a in the Control of Abnormal Mitochondrial Dynamics in Alzheimer’s Disease

Emerging evidence suggests that the proper control of mitochondrial dynamics provides a window for therapeutic intervention for Alzheimer’s disease (AD) progression. The transcriptional coactivator peroxisome proliferator activated receptor gamma coactivator 1 (PGC-1a) has been shown to regulate mitochondrial biogenesis in neurons. Thus far, the roles of PGC-1a in Alzheimer’s disease and its potential value for restoring mitochondrial dysfunction remain largely unknown. In the present study, we explored the impacts of PGC-1a on AD pathology and neurobehavioral dysfunction and its potential mechanisms with a particular focus on mitochondrial dynamics. Paralleling AD-related pathological deposits, neuronal apoptosis, abnormal mitochondrial dynamics and lowered membrane potential, a remarkable reduction in the expression of PGC-1a was shown in the cortex of APP/PS1 mice at 6 months of age. By infusing AAV-Ppargc1α into the lateral parietal association (LPtA) cortex of the APP/PS1 brain, we found that PGC-1a ameliorated AD-like behavioral abnormalities, such as deficits in spatial reference memory, working memory and sensorimotor gating. Notably, overexpressed PGC-1a in LPtA rescued mitochondrial swelling and damage in neurons, likely through correcting the altered balance in mitochondrial fission–fusion and its abnormal distribution. Our findings support the notion that abnormal mitochondrial dynamics is likely an important mechanism that leading to mitochondrial dysfunction and AD-related pathological and cognitive impairments, and they indicate the potential value of PGC-1a for restoring mitochondrial dynamics as an innovative therapeutic target for AD.

FOXG1 as a Potential Therapeutic Target for Alzheimer's Disease with a Particular Focus on Cell Cycle Regulation

BACKGROUND

Several recent findings have revealed that targeting of cell cycle reentry and (or) progression may provide an opportunity for the therapeutic intervention of Alzheimer's disease (AD). FOXG1 has been shown to play important roles in pattern formation, cell proliferation, and cell specification. Thus far, the roles of FoxG1 and its involvement in AD are largely unknown.

OBJECTIVE

Our study aimed to explore the intervention effect of FOXG1 on AD pathology and its potential mechanism with a particular focus on cell cycle regulation.

METHODS

We investigated the association of Foxg1 gene variants with AD-like behavioral deficits, p21 expression, neuronal apoptosis, and amyloid-β (Aβ) aggregate formation; we further determined whether targeting FOXG1-regulated cell cycle has therapeutic potential in AD.

RESULTS

Paralleling AD-like behavioral abnormalities, neuronal apoptosis, and Aβ deposits, a significant reduction in the expression of FOXG1 was observed in APP/PS1 mice at 6 months of age. Using the APP/PS1;Foxg1fl/fl-CreAAV mouse line, we found that FOXG1 potentially antagonized cell cycle reentry by negatively regulating the levels of p21-activated kinase (PAK3). By reducing p21cip1-mediated arrest at the G2 stage and regulating cyclin A1- and cyclin B-dependent progression patterns of the cell cycle, FOXG1 blocked neuronal apoptosis and Aβ deposition.

CONCLUSION

These results indicate that FOXG1 contributes to the regulation of the neuronal cell cycle, thereby affecting brain abnormalities in AD. An elevation of the FOXG1 level, either pharmacologically or through other means, could present a therapeutic strategy for AD.

The shallow cognitive map hypothesis: A hippocampal framework for thought disorder in schizophrenia

Memories are not formed in isolation. They are associated and organized into relational knowledge structures that allow coherent thought. Failure to express such coherent thought is a key hallmark of Schizophrenia. Here we explore the hypothesis that thought disorder arises from disorganized Hippocampal cognitive maps. In doing so, we combine insights from two key lines of investigation, one concerning the neural signatures of cognitive mapping, and another that seeks to understand lower-level cellular mechanisms of cognition within a dynamical systems framework. Specifically, we propose that multiple distinct pathological pathways converge on the shallowing of Hippocampal attractors, giving rise to disorganized Hippocampal cognitive maps and driving conceptual disorganization. We discuss the available evidence at the computational, behavioural, network, and cellular levels. We also outline testable predictions from this framework, including how it could unify major chemical and psychological theories of schizophrenia and how it can provide a rationale for understanding the aetiology and treatment of the disease.

Covering the Role of PGC-1α in the Nervous System

The peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a well-known transcriptional coactivator involved in mitochondrial biogenesis. PGC-1α is implicated in the pathophysiology of many neurodegenerative disorders; therefore, a deep understanding of its functioning in the nervous system may lead to the development of new therapeutic strategies. The central nervous system (CNS)-specific isoforms of PGC-1α have been recently identified, and many functions of PGC-1α are assigned to the particular cell types of the central nervous system. In the mice CNS, deficiency of PGC-1α disturbed viability and functioning of interneurons and dopaminergic neurons, followed by alterations in inhibitory signaling and behavioral dysfunction. Furthermore, in the ALS rodent model, PGC-1α protects upper motoneurons from neurodegeneration. PGC-1α is engaged in the generation of neuromuscular junctions by lower motoneurons, protection of photoreceptors, and reduction in oxidative stress in sensory neurons. Furthermore, in the glial cells, PGC-1α is essential for the maturation and proliferation of astrocytes, myelination by oligodendrocytes, and mitophagy and autophagy of microglia. PGC-1α is also necessary for synaptogenesis in the developing brain and the generation and maintenance of synapses in postnatal life. This review provides an outlook of recent studies on the role of PGC-1α in various cells in the central nervous system.

Attractin Gene Deficiency in Rats Leads to Impairments in Both Activity and Spatial Learning and Memory

Attractin (ATRN), an autosomal recessive gene that is widely distributed in the brain, is involved in the execution of a variety of brain functions and associated with certain neuropsychiatric disorders. Here, we introduce a novel rat strain harboring a mutation in ATRN that was generated by knocking in ATRN-G505C via the CRISPR/Cas9 system. We assessed the behavioral performance of these mutant ATRN knock-in rats. The G505C mutation was introduced into exon 9, and a synthetic primer was inserted into introns 8-9 for genotyping. The 505th amino acid, a Gly (G) residue, was mutated to a Cys (C) residue, i.e., GGC was mutated to TGC. Behavioral experiments showed that homozygous ATRN rats spent significantly more time searching for the escape platform in the acquisition trial and significantly less time in the target area in the probe trial in the Morris water maze (MWM) test and traveled a significantly shorter distance in the open field test (OFT) than wild-type rats. In addition, Western blot analysis and immunohistochemistry showed that rats with the mutant ATRN gene exhibited significantly reduced expression of brain-derived neurotrophic factor (BDNF). In summary, our results indicate that mutations in the ATRN gene directly lead to learning and memory impairments and slight motor deficits. These findings provide new clues for the mechanism by which mutant ATRN induces neurodegenerative changes.

Dysregulation of PGC-1α-Dependent Transcriptional Programs in Neurological and Developmental Disorders: Therapeutic Challenges and Opportunities

Substantial evidence indicates that mitochondrial impairment contributes to neuronal dysfunction and vulnerability in disease states, leading investigators to propose that the enhancement of mitochondrial function should be considered a strategy for neuroprotection. However, multiple attempts to improve mitochondrial function have failed to impact disease progression, suggesting that the biology underlying the normal regulation of mitochondrial pathways in neurons, and its dysfunction in disease, is more complex than initially thought. Here, we present the proteins and associated pathways involved in the transcriptional regulation of nuclear-encoded genes for mitochondrial function, with a focus on the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1α). We highlight PGC-1α’s roles in neuronal and non-neuronal cell types and discuss evidence for the dysregulation of PGC-1α-dependent pathways in Huntington’s Disease, Parkinson’s Disease, and developmental disorders, emphasizing the relationship between disease-specific cellular vulnerability and cell-type-specific patterns of PGC-1α expression. Finally, we discuss the challenges inherent to therapeutic targeting of PGC-1α-related transcriptional programs, considering the roles for neuron-enriched transcriptional coactivators in co-regulating mitochondrial and synaptic genes. This information will provide novel insights into the unique aspects of transcriptional regulation of mitochondrial function in neurons and the opportunities for therapeutic targeting of transcriptional pathways for neuroprotection.

Dysregulation of PGC-1α-Dependent Transcriptional Programs in Neurological and Developmental Disorders: Therapeutic Challenges and Opportunities

Substantial evidence indicates that mitochondrial impairment contributes to neuronal dysfunction and vulnerability in disease states, leading investigators to propose that the enhancement of mitochondrial function should be considered a strategy for neuroprotection. However, multiple attempts to improve mitochondrial function have failed to impact disease progression, suggesting that the biology underlying the normal regulation of mitochondrial pathways in neurons, and its dysfunction in disease, is more complex than initially thought. Here, we present the proteins and associated pathways involved in the transcriptional regulation of nuclear-encoded genes for mitochondrial function, with a focus on the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1α). We highlight PGC-1α's roles in neuronal and non-neuronal cell types and discuss evidence for the dysregulation of PGC-1α-dependent pathways in Huntington's Disease, Parkinson's Disease, and developmental disorders, emphasizing the relationship between disease-specific cellular vulnerability and cell-type-specific patterns of PGC-1α expression. Finally, we discuss the challenges inherent to therapeutic targeting of PGC-1α-related transcriptional programs, considering the roles for neuron-enriched transcriptional coactivators in co-regulating mitochondrial and synaptic genes. This information will provide novel insights into the unique aspects of transcriptional regulation of mitochondrial function in neurons and the opportunities for therapeutic targeting of transcriptional pathways for neuroprotection.

PGC-1α reduces Amyloid-β deposition in Alzheimer's disease: Effect of increased VDR expression

Amyloid-β (Aβ) is the core component of amyloid plaques of Alzheimer's disease (AD). Recent evidence has confirmed that Aβ triggers neurodegeneration by dramatically suppressing vitamin D receptor (VDR) expression. Thus far, the onset mechanisms and means of preventing AD are largely unknown. Perioxisome proliferator-activated receptor-γ coactivator (PGC-1α), as a transcriptional coactivator of VDR could protect cells against oxidative stress. Thus, upregulation of PGC-1α is a candidate therapeutic strategy for AD. To investigate the effect of PGC-1α in AD, and to illuminate the precise involvement of VDR in the neuroprotective strategy, the varies of molecular of PGC-1α and VDR were studied in APP/PS-1 double transgenic (2xTg-AD) mice at 6 months of age, significant reduction in the expression of PGC-1α and VDR was found in their hippocampus and the cortex. Besides, a specific mouse line, Dlx5/6-Cre:PGC-1α^fl/fl in which the PGC-1α deficiency was limited to the hippocampus and the cortex, was used to study the target intervention of PGC-1α, decreased expression of VDR and increased oxidative damage were observed in AD-related brain regions by PGC-1α deficiency. To explore the function and therapeutic strategy of PGC-1α in AD, an adeno-associated virus (AAV) was used to induce PGC-1α overexpressed in the hippocampus of 2xTg-AD mice. Overexpressed PGC-1α results in a remarkable increase in the levels of VDR associated with a significant reduction in the expression of Aβ plaques and of 8-oxo-dG in 2xTg-AD mice. These data may have ramifications for neuroprotective strategies targeting overexpression of PGC-1α in Alzheimer's disease.

Enhancing excitatory projections from the ventral subiculum to the nucleus accumbens shell contribute to the MK-801-induced impairment of prepulse inhibition

Prepulse inhibition (PPI), a measure of sensorimotor gating, has been shown to be disrupted in several animal models of neuropsychiatric disorders, such as schizophrenia. The neural circuits involving the hippocampus and nucleus accumbens (NAC) have been studied in rats to uncover the neurochemical and neuroanatomical substrates that regulate PPI. Majority of the studies of the hippocampus on PPI to date have been focused on CA1, CA2, and dentate gyrus (DG) area. Little is known about the role of the subiculum, which maintains the hippocampal formation intact, on the sensorimotor gating. In this study, the PPI disruption was induced by intraperitoneal injection of MK-801 in rats, and the neuronal activity in the dorsal and ventral subiculum by c-Fos immunostaining was examined. The projections from the subiculum to the nucleus accumbens (NAC) were detected by retrograde tracing of cholera toxin B subunit, in the PPI dysfunctional animals. The results showed an increase in neuronal activity in the ventral subiculum (vSub) while remaining constant in the dorsal subiculum during PPI disruption. The excitatory projections from the vSub to the NAC shell were significantly enhanced when PPI was disrupted. Muscimol Inhibition of vSub could significantly ameliorate the MK801-induced PPI deficit. This data suggests that the enhancement of neuronal activity in the vSub was associated with the PPI impairment, possibly due to the enhanced excitatory output from vSub the NAC shell.

PGC-1α regulate critical period plasticity via gene × environment interaction in the developmental trajectory to schizophrenia

Genes and environmental conditions are thought to interact in the development of postnatal brain in schizophrenia (SZ). Genome wide association studies have identified that PPARGC1A being one of the top candidate genes for SZ. We previously reported GABAergic neuron-specific PGC-1α knockout mice (Dlx5/6-Cre:PGC-1α^fl/fl) presented some characteristic features of SZ. However, there is a fundamental gap of the molecular mechanism by which PGC-1α gene involved in the developmental trajectory to SZ. To explore whether PGC-1α regulates environmental factors interacting with genetic susceptibility to trigger symptom onset and disease progression, PGC-1α deficient mice were utilized to model genetic effect and an additional oxidative stress was induced by GBR injection. We confirm that PGC-1α gene deletion prolongs critical period (CP) timing, as revealed by delaying maturation of PV interneurons (PVIs), including their perineuronal nets (PNNs). Further, we confirm that gene × environment (G × E) influences CP plasticity synergistically and the interaction varies as a function of age, with the most sensitive period being at preweaning stage, and the least sensitive one at early adult age in PGC-1α deficient mice. Along this line, we find that the synergic action of G × E is available in ChABC-infusion PGC-1α KO mice, even though during the adulthood, and the neuroplasticity seems to remain open to fluctuate. Altogether, these results refine the observations made in the PGC-1α deficient mice, a potential mouse model of SZ, and illustrate how PGC-1α regulates CP plasticity via G × E interaction in the developmental trajectory to SZ.