Improved Methods for Fluorescence Microscopy Detection of Macromolecules at the Axon Initial Segment

The axonal initial segment (AIS) is the subcellular compartment required for initiation of the action potential in neurons. Scaffolding and regulatory proteins at the AIS cluster with ion channels ensuring the integrity of electrical signaling. Interference with the configuration of this protein network can lead to profound effects on neuronal polarity, excitability, cell-to-cell connectivity and brain circuit plasticity. As such, the ability to visualize AIS components with precision provides an invaluable opportunity for parsing out key molecular determinants of neuronal function. Fluorescence-based immunolabeling is a sensitive method for morphological and molecular characterization of fine structures in neurons. Yet, even when combined with confocal microscopy, detection of AIS elements with immunofluorescence has been limited by the loss of antigenicity caused by fixative materials. This technical barrier has posed significant limitations in detecting AIS components alone or in combination with other markers. Here, we designed improved protocols targeted to confocal immunofluorescence detection of the AIS marker fibroblast growth factor 14 (FGF14) in combination with the cytoskeletal-associated protein Ankyrin-G, the scaffolding protein βIV-spectrin, voltage-gated Na+ (Nav) channels (especially the Nav1.6 isoform) and critical cell type-specific neuronal markers such as parvalbumin, calbindin, and NeuN in the mouse brain. Notably, we demonstrate that intracardiac perfusion of animals with a commercially available solution containing 1% formaldehyde and 0.5% methanol, followed by brief fixation with cold acetone is an optimal and sensitive protocol for FGF14 and other AIS marker detection that guarantees excellent tissue integrity. With variations in the procedure, we also significantly improved the detection of Nav1.6, a Nav isoform known for its fixative-sensitivity. Overall, this study provides an ensemble of immunohistochemical recipes that permit excellent staining of otherwise invisible molecules within well-preserved tissue architecture. While improving the specific investigation of AIS physiology and cell biology, our thorough study can also serve as a roadmap for optimizing immunodetection of other fixative-sensitive proteins expanding the repertoire of enabling methods for brain studies

Examining bedtime procrastination, study engagement, and studyholism in undergraduate students, and their association with insomnia

IntroductionCompulsive overstudying, known as studyholism, is an emerging behavioral addiction. In this study, we examine the prevalence of, and the relationships between, insomnia, study engagement, studyholism, bedtime procrastination among undergraduate students.MethodsThe Studyholism (SI-10), Athens Insomnia (AIS), and bedtime procrastination scales were administered to a convenience sample of 495 university students.ResultsOur findings indicate that the prevalence of insomnia was 75.31%, high studyholism was found in 15.31% of the sample, and increased study engagement was detected in 16.94%. Gender differences analysis revealed that females reported higher studyholism and bedtime procrastination than males. Fifth-year students had higher levels of studyholism than internship (p < 0.001), first-year (p < 0.01), and sixth-year students (p < 0.05). Insomnia was positively related to studyholism and bedtime procrastination. Furthermore, insomnia can be positively predicted by studyholism and bedtime procrastination. Participants with a medium level of studyholism were twice as likely to experience insomnia as those with a low level. Studyholics were six times more susceptible to insomnia than students with low studyholism levels. Compared to individuals with low bedtime procrastination levels, those with medium and high bedtime procrastination were twice as likely to report insomnia.ConclusionOur study highlights the interplay between insomnia, studyholism, and bedtime procrastination. Further, the findings indicate the need to increase awareness of insomnia

The Association Between Hypertension and Insomnia Among Saudi Population: A Cross-Sectional Study

Objective To assess the relationship between hypertension and insomnia among the Saudi population. Methods The study will employ a cross-sectional design to investigate the association between hypertension and insomnia among the Saudi population. This design allows for the collection of data at a single point in time, offering insights into the relationship between the variables. Results The study included 581 participants. The most frequent age among them was 18-28 (n= 266, 45.8 Per Cent), followed by 29-39 (n= 129, 22.2 Per Cent). The most frequent gender among study participants was female (n= 320, 55.1 Per Cent), followed by male (n= 261, 44.9 Per Cent). Study participants' most frequent body mass index was normal 18.5-24.9 kg/m2 (n= 231, 39.8 Per Cent) followed by overweight 25-29.9 kg/m2 (n= 200, 34.4 Per Cent). Marital status among study participants, with most of them being single (n=283, 48.7 Per Cent) followed by married (n= 238, 41 Per Cent). The number of hours of sleep during the day among study participants with most of them had 6-8 hours. Participants were asked if they had difficulty sleeping. There most of the participants were nothing (n= 201, 34.6 Per Cent). On the other hand, 154 participants had middle (26.5 Per Cent). They asked if they had difficulty staying asleep. There most of the participants were nothing (n= 227, 39.1 Per Cent). On the other hand, 152 participants had middle (26.2 Per Cent). Participants were asked if they had trouble waking up early. There most of the participants were nothing (n= 189, 32.5 Per Cent). Followed by middle (n=148, 25.5 Per Cent). Conclusion The results of the study showed that most of the study participants were of normal weight according to their body mass index. Most of them are single. Most participants sleep approximately 6-8 hours a day. The largest percentage of participants work in the government or private sector. Most of them had good social contact

Neuroinflammatory Cytokines Induce Amyloid Beta Neurotoxicity through Modulating Amyloid Precursor Protein Levels/Metabolism

Neuroinflammation has been observed in association with neurodegenerative diseases including Alzheimer’s disease (AD). In particular, a positive correlation has been documented between neuroinflammatory cytokine release and the progression of the AD, which suggests these cytokines are involved in AD pathophysiology. A histological hallmark of the AD is the presence of beta-amyloid (Aβ) plaques and tau neurofibrillary tangles. Beta-amyloid is generated by the sequential cleavage of beta (β) and gamma (γ) sites in the amyloid precursor protein (APP) by β- and γ-secretase enzymes and its accumulation can result from either a decreased Aβ clearance or increased metabolism of APP. Previous studies reported that neuroinflammatory cytokines reduce the efflux transport of Aβ, leading to elevated Aβ concentrations in the brain. However, less is known about the effects of neuroinflammatory mediators on APP expression and metabolism. In this article, we review the modulatory role of neuroinflammatory cytokines on APP expression and metabolism, including their effects on β- and γ-secretase enzymes

Pharmacological Modulation of Toll-Like Receptors in Brain Disorders

The knowledge regarding pathological and treatment resistance mechanisms involved in the pathology of complex brain disorders is far from understood. The neuroinflammation hypothesis of psychiatric, neurological, and neurodegenerative diseases is well-acknowledged. However, this hypothesis is far from understood. Toll-like receptors (TLRs) family is an innate immunity molecule implicated in neuroinflammation in complex brain disorders. This chapter reviews considerable evidence indicating that activation of endotoxins such as lipopolysaccharide is a common factor. Additionally, we report clinical and preclinical studies highlighting the link between lipopolysaccharide, TLRs, and different types of brain disorders. Also, we review the current pharmacological modulations of TLRs. Hoping we would help in filling our knowledge gaps and highlight potential links to tackle new angles in managing complex brain disorders. This chapter’s primary goal is to encourage scientists and researchers to conduct future studies characterizing the nature of endotoxin activation of TLRs in complex brain disorders, filling our knowledge gaps, and finding new treatment strategies

Porous Polyethylene Coated with Functionalized Hydroxyapatite Particles as a Bone Reconstruction Material

In this study, porous polyethylene scaffolds were examined as bone substitutes in vitro and in vivo in critical-sized calvarial bone defects in transgenic Sprague-Dawley rats. A microscopic examination revealed that the pores appeared to be interconnected across the material, making them suitable for cell growth. The creep recovery behavior of porous polyethylene at different loads indicated that the creep strain had two main portions. In both portions, strain increased with increased applied load and temperature. In terms of the thermographic behavior of the material, remarkable changes in melting temperature and heat fusion were revealed with increased the heating rates. The tensile strength results showed that the material was sensitive to the strain rate and that there was adequate mechanical strength to support cell growth. The in vitro cell culture results showed that human bone marrow mesenchymal stem cells attached to the porous polyethylene scaffold. Calcium sulfate–hydroxyapatite (CS–HA) coating of the scaffold not only improved attachment but also increased the proliferation of human bone marrow mesenchymal stem cells. In vivo, histological analysis showed that the study groups had active bone remodeling at the border of the defect. Bone regeneration at the border was also evident, which confirmed that the polyethylene acted as an osteoconductive bone graft. Furthermore, bone formation inside the pores of the coated polyethylene was also noted, which would enhance the process of osteointegration

Perspective Chapter: Ketamine, Depression, and Gender Bias

Our knowledge regarding pathological and treatment resistance mechanisms involved in depression is far from understood. Sexual dimorphism in this topic is well acknowledged. However, the need to highlight sex-based discrepancies is unmet. Ketamine, the dissociative anesthetic, has emerged as a rapid antidepressant. This chapter reviewed sexual dimorphism in pharmacological and genetic models of depression, emphasizing ketamine-related antidepressant effects. Aiming by this report, we would extend our knowledge, highlight gender as one of the vital factors in examining depression in preclinical studies, and elucidate complex antidepressant effects associated with ketamine administration. Our central goal is to encourage neuroscientists to consider gender in their studies of mood disorders

Parallel fiber to Purkinje cell synaptic impairment in a mouse model of spinocerebellar ataxia type 27

Genetically inherited mutations in the fibroblast growth factor 14 (FGF14) gene lead to spinocerebellar ataxia type 27 (SCA27), an autosomal dominant disorder characterized by severe heterogeneous motor and cognitive impairments. Consistently, genetic deletion of Fgf14 in Fgf14-/- mice recapitulates salient features of the SCA27 human disease. In vitro molecular studies in cultured neurons indicate that the FGF14F145S SCA27 allele acts as a dominant negative mutant suppressing the FGF14 wild type function and resulting in inhibition of voltage-gated Na+ and Ca2+ channels. To gain insights in the cerebellar deficits in the animal model of the human disease, we applied whole-cell voltage-clamp in the acute cerebellar slice preparation to examine the properties of parallel fibers (PF) to Purkinje neuron synapses in Fgf14-/- mice and wild type littermates. We found that the AMPA receptor-mediated excitatory postsynaptic currents evoked by PF stimulation (PF-EPSCs) were significantly reduced in Fgf14-/- animals, while short-term plasticity, measured as paired-pulse facilitation (PPF), was enhanced. Measuring Sr2+-induced release of quanta from stimulated synapses, we found that the size of the PF-EPSCs was unchanged, ruling out a postsynaptic deficit. This phenotype was corroborated by decreased expression of VGLUT1, a specific presynaptic marker at PF-Purkinje neuron synapses. We next examined the mGluR1 receptor-induced response (mGluR1-EPSC) that under normal conditions requires a gradual build-up of glutamate concentration in the synaptic cleft, and found no changes in these responses in Fgf14-/- mice. These results provide evidence of a critical role of FGF14 in maintaining presynaptic function at PF-Purkinje neuron synapses highlighting critical target mechanisms to recapitulate the complexity of the SCA27 disease

Assessing the role of toll-like receptor in isolated, standard and enriched housing conditions.

Depression is a common psychiatric disorder that has been poorly understood. Consequently, current antidepressant agents have clinical limitations. Until today, most have exhibited the slow onset of therapeutic action and, more importantly, their effect on remission has been minimal. Thus, the need to find new forms of therapeutic intervention is urgent. The inflammation hypothesis of depression is widely acknowledged and is one that theories the relationship between the function of the immune system and its contribution to the neurobiology of depression. In this research, we utilized an environmental isolation (EI) approach as a valid animal model of depression, employing biochemical, molecular, and behavioral studies. The aim was to investigate the anti-inflammatory effect of etanercept, a tumor necrosis factor-α inhibitor on a toll-like receptor 7 (TLR 7) signaling pathway in a depressive rat model, and compare these actions to fluoxetine, a standard antidepressant agent. The behavioral analysis indicates that depression-related symptoms are reduced after acute administration of fluoxetine and, to a lesser extent, etanercept, and are prevented by enriched environment (EE) housing conditions. Experimental studies were conducted by evaluating immobility time in the force swim test and pleasant feeling in the sucrose preference test. The mRNA expression of the TLR 7 pathway in the hippocampus showed that TLR 7, MYD88, and TRAF6 were elevated in isolated rats compared to the standard group, and that acute treatment with an antidepressant and anti-inflammatory drugs reversed these effects. This research indicates that stressful events have an impact on behavioral well-being, TLR7 gene expression, and the TLR7 pathway. We also found that peripheral administration of etanercept reduces depressive-like behaviour in isolated rats: this could be due to the indirect modulation of the TLR7 pathway and other TLRs in the brain. Furthermore, fluoxetine treatment reversed depressive-like behaviour and molecularly modulated the expression of TLR7, suggesting that fluoxetine exerts antidepressant effects partially by modulating the TLR7 signaling pathway