Biochemical Changes Indicate Developmental Stage in the Hippocampal Formation

Regulation mechanisms of sea cucumber peptides against scopolamine-induced memory disorder and novel memory-improving peptides identification

Memory impairment affects cognition and information processing, and attention, leading to a decline in life quality of patients. Previous studies have shown the memory-improving effects of sea cucumber peptides. This study further explored the memory-improving mechanisms of sea cucumber peptides using scopolamine-induced memory-impaired mice and identified novel memory-improving peptides within low molecular weight peptide fractions. The sea cucumber peptides were categorized into three groups based on their molecular weights: SCP-L (molecular weight greater than 10 kDa), SCP-M (weight between 3 kDa and 10 kDa), and SCP-S (molecular weight less than 3 kDa). The results showed that SCP-S improved behavioral performance by regulating cholinergic system disorder and reducing oxidative stress levels, distinguishing itself from SCP-M and SCP-L. Further, SCP-S was found to exhibit a well ability in alleviating the degree of neuroinflammation dependent on microglia and promoting synaptic plasticity. Additionally, a novel memory-improving peptide Ser-Phe-Gly-Asp-Ile (SFGDI) was identified by EASY-nano-LC/MS/MS after simulated digestion-absorption coupling of in silico technologies from SCP-S. SFGDI protected against oxidative stress and regulated cholinergic system in scopolamine-induced PC12 cells. These findings suggest that SCP-S and SFGDI might be considered as potential memory-improving food for people suffering from memory disorders.

A Novel Tetrapeptide Ala-Phe-Phe-Pro (AFFP) Derived from Antarctic Krill Prevents Scopolamine-Induced Memory Disorder by Balancing Lipid Metabolism of Mice Hippocampus

Memory impairment is a serious problem with organismal aging and increased social pressure. The tetrapeptide Ala-Phe-Phe-Pro (AFFP) is a synthetic analogue of Antarctic krill derived from the memory-improving Antarctic krill peptide Ser-Ser-Asp-Ala-Phe-Phe-Pro-Phe-Arg (SSDAFFPFR) after digestion and absorption. The objective of this research was to assess the neuroprotective effects of AFFP by reducing oxidative stress and controlling lipid metabolism in the brains of mice with memory impairment caused by scopolamine. The 1H Nuclear magnetic resonance spectroscopy results showed that AFFP had three active hydrogen sites that could contribute to its antioxidant properties. The findings from in vivo tests demonstrated that AFFP greatly enhanced the mice's behavioral performance in the passive avoidance, novel object recognition, and eight-arm maze experiments. AFFP reduced oxidative stress by enhancing superoxide dismutase activity and malondialdehyde levels in mice serum, thereby decreasing reactive oxygen species level in the mice hippocampus. In addition, AFFP increased the unsaturated lipid content to balance the unsaturated lipid level against the neurotoxicity of the mice hippocampus. Our findings suggest that AFFP emerges as a potential dietary intervention for the prevention of memory impairment disorders.

Vibrational spectroscopy methods for investigation of the animal models of glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most common and devastating primary brain tumor among adults. It is highly lethal disease, as only 25% of patients survive longer than 1 year and only 5% more than 5 years from the diagnosis. To search for the new, more effective methods of treatment, the understanding of mechanisms underlying the process of tumorigenesis is needed. The new light on this problem may be shed by the analysis of biochemical anomalies of tissues affected by tumor growth. Therefore, in the present work, we applied the Fourier transform infrared (FTIR) and Raman microspectroscopy to evaluate changes in the distribution and structure of biomolecules appearing in the rat brain as a result of glioblastoma development. In turn, synchrotron X-ray fluorescence microscopy was utilized to determine the elemental anomalies appearing in the nervous tissue. To achieve the assumed goals of the study animal models of GBM were used. The rats were subjected to the intracranial implantation of glioma cells with different degree of invasiveness. For spectroscopic investigation brain slices taken from the area of cancer cells administration were used. The obtained results revealed, among others, the decrease content of lipids and compounds containing carbonyl groups, compositional and structural changes of proteins as well as abnormalities in the distribution of low atomic number elements within the region of tumor.

Roadmap for Postnatal Brain Maturation: Changes in Gray and White Matter Composition during Development Measured by Fourier Transformed Infrared Microspectroscopy

Key events in postnatal brain development, such as neuronal migration, synaptogenesis, and myelination, shape the adult brain. These events are reflected in changes in gray and white matter (GM and WM) occurring during this period. Therefore, precise knowledge of GM and WM composition in perinatal brain development is crucial to characterizing brain formation as well as the neurodevelopmental disruption observed in diseases such as autism and schizophrenia. In this study, we combined histochemical and immunohistochemical staining with biochemical and biophysical analyses using Fourier transform infrared (IR) microspectroscopy (μFTIR) to better understand the chemical changes during postnatal developmental myelination. For this purpose, we analyzed the GM and WM in the mouse brain and cerebellum (strain C57BL/6) from postnatal day 0 (P0) to day P28 and established presumed correlations between staining and IR data. IR spectra allowed the (i) quantification of lipid and protein content through the CH2/amide I ratio, (ii) determination of chemical characteristics of lipids, such as the presence of unsaturated bonds in the carbonate chain or carbonyls from ester groups in the polar head, and (iii) determination of the protein secondary structure (α-helix and intramolecular β-sheets). The results indicate that the increase in the CH2/amide I ratio calculated from the μFTIR data correlates well with lipid histochemical staining. IR data indicated a change in the lipid composition in WM since carbonyl and unsaturated olefinic groups do not increase when lipids accumulate during myelination. Our correlation analysis between IR data and immunohistochemical staining of myelin-associated proteins revealed that myelin oligodendrocyte protein correlated well with lipid accumulation, while myelin basic protein appeared before lipid modifications, which indicated that myelin-associated proteins and lipid deposition were not synchronic. These events were related to a decrease in the intramolecular β/α protein ratio. Our results indicate that lipids and proteins in WM substantially change their composition due to primary myelination, and according to results obtained from staining, these modifications are better described by lipid histochemical staining than by immunohistochemistry against myelin-related proteins. In conclusion, μFTIR can be a useful technique to study WM during perinatal development and provide detailed information about alterations in the chemical composition related to neurodevelopmental diseases.

Does Ketogenic Diet Used in Pregnancy Affect the Nervous System Development in Offspring?─FTIR Microspectroscopy Study

Anti-seizure medications used during pregnancy may have transient or long-lasting impact on the nervous system of the offspring. Therefore, there is a great need to search for alternative therapies for pregnant women suffering from seizures. One of the solutions may be the use of the ketogenic diet (KD), which has been successfully applied as a treatment of drug-resistant epilepsy in children and adults. However, the risks associated with the use of this dietary therapy during pregnancy are unknown and more investigation in this area is needed. To shed some light on this problem, we attempted to determine the potential abnormalities in brain biomolecular composition that may occur in the offspring after the prenatal exposure to KD. To achieve this, the female Wistar rats were, during pregnancy, fed with either ketogenic or standard laboratory diet, and for further studies, their male offspring at 2, 6, or 14 days of age were used. Fourier transform infrared microspectroscopy was applied for topographic and quantitative analysis of main biological macromolecules (proteins, lipids, compounds containing phosphate and carbonyl groups, and cholesterol) in brain samples. Performed chemical mapping and further semi-quantitative and statistical analysis showed that the use of the KD during pregnancy, in general, does not lead to the brain biochemical anomalies in 2 and 6 days old rats. The exception from this rule was increased relative (comparing to proteins) content of compounds containing phosphate groups in white matter and cortex of 2 days old rats exposed prenatally to KD. Greater number of abnormalities was found in brains of the 14 days old offspring of KD-fed mothers. They included the increase of the relative level of compounds containing carbonyl groups (in cortex as well as multiform and molecular cells of the hippocampal formation) as well as the decrease of the relative content of lipids and their structural changes (in white matter). What is more, the surface of the internal capsule (structure of the white matter) determined for this age group was smaller in animals subjected to prenatal KD exposure. The observed changes seem to arise from the elevated exposition to ketone bodies during a fetus life and the disturbance of lipid metabolism after prenatal exposure to the KD. These changes may be also associated with the processes of compensation of mother organism, which slowly began to make up for the deficiencies in carbohydrates postpartum.

LYC loaded ferritin nanoparticles for intracerebral delivery and the attenuation of neurodegeneration in D-gal-induced mice

Recombinant human H-ferritin nanocage (rHuHF) loaded with natural antioxidative lycopene molecules (LYC) was successfully constructed for the first time, aiming to enrich LYC in the brain and explore the regulation mechanism of this nanoparticles on neurodegeneration. Here, the mouse model was constructed via D-galactose-induced neurodegeneration based on behavioural analysis, histological observation, immunostaining analysis, Fourier transform infrared microscopy, and Western blotting analysis for the regulation of rHuHF-LYC. rHuHF-LYC improved the behaviour of mice in a dose-dependent manner. Besides, rHuHF-LYC can attenuate neuronal damage, maintain the number of Nissl body, increase the level of unsaturated fat, inhibit the activation of glial cells, and prevent excessive accumulation of neurotoxic proteins in the hippocampus of mice. More importantly, synaptic plasticity was activated in response to the regulation of rHuHF-LYC with excellent biocompatibility and biosafety. This study proved the validity of the direct use of natural antioxidant nano drugs for treating neurodegeneration, providing a promising therapeutic option against further imbalances in the degenerative brain microenvironment.

Sea Cucumber Peptides Attenuated the Scopolamine-Induced Memory Impairment in Mice and Rats and the Underlying Mechanism

Social stress and unhealthy diets lead to memory impairment, triggering health problems. This study aimed to determine the mitigating effect and regulation mechanism of sea cucumber peptides (SCP) against memory impairment. Here, scopolamine-induced memory impairment in mouse and rat models was used based on behavioral tests, a histological staining technique, Fourier transform infrared microscopy, and gas-chromatographic analysis as well as a Western blotting method. SCP improved the behavioral performance and regulated the disorder of the cholinergic system in mouse models in a dose-dependent manner. Therefore, the underlying mechanism was explored in high-dose SCP using mouse and rat models. SCP repaired damaged neuronal cells, enhanced the Nissl body number, increased the unsaturated lipid level, and activated the long-term potentiation (LTP) pathway (p-CaMKII, p-CREB, and BDNF), both in the mouse and rat hippocampus. The results indicated that SCP upregulated the LTP pathway and unsaturated lipid level to combat scopolamine-induced memory impairment, suggesting that SCP was a potential candidate for neurological recovery.

The Use of Fourier Transform Infrared Microspectroscopy for the Determination of Biochemical Anomalies of the Hippocampal Formation Characteristic for the Kindling Model of Seizures

The animal models of seizures and/or epilepsy are widely used to identify the pathomechanisms of the disease as well as to look for and test the new antiseizure therapies. The understanding of the mechanisms of action of new drugs and evaluation of their safety in animals require previous knowledge concerning the biomolecular anomalies characteristic for the particular model. Among different models of seizures, one of the most widely used is the kindling model that was also applied in our study. To examine the influence of multiple transauricular electroshocks on the biochemical composition of rat hippocampal formation, Fourier transform infrared (FT-IR) microspectrosopy was utilized. The chemical mapping of the main absorption bands and their ratios allowed us to detect significant anomalies in both the distribution and structure of main biomolecules for electrically stimulated rats. They included an increased relative content of proteins with β-sheet conformation (an increased ratio of the absorbance at the wavenumbers of 1635 and 1658 cm^–1), a decreased level of cholesterol and/or its esters and compounds containing phosphate groups (a diminished intensity of the massif of 1360–1480 cm^–1 and the band at 1240 cm^–1), as well as increased accumulation of carbohydrates and the compounds containing carbonyl groups (increased intensity of the bands at 1080 and 1740 cm^–1, respectively). The observed biomolecular abnormalities seem to be the consequence of lipid peroxidation promoted by reactive oxygen species as well as the mobilization of glucose that resulted from the increased demand to energy during postelectroshock seizures.

Alarmin HMGB1 Plays a Detrimental Role in Hippocampal Dysfunction Caused by Hypoxia-Ischemia Insult in Neonatal Mice: Evidence from the Application of the HMGB1 Inhibitor Glycyrrhizin

Hippocampal dysfunction related to cognitive impairment and emotional disorders in young children and adolescents caused by neonatal hypoxic-ischemic brain injury (HIBI) has attracted increasing attention in recent years. Crosstalk between the nervous and immune systems organized by hypoxia-ischemia (HI) insult may contribute to hippocampal dysfunction after HIBI. Extracellular HMGB1 functions as a damage-associated molecular pattern to instigate and amplify inflammatory responses, but whether this molecule is correlated with hippocampal dysfunction after HIBI is largely unknown. Therefore, this study examined hippocampal function after HMGB1 inhibition in an experimental HIBI model to verify the hypothesis that HMGB1 is a key mediator of hippocampal neuropathology in neonatal HIBI. By administering different doses of the HMGB1-specific inhibitor glycyrrhizin (GLY), we first found that GLY reversed the HI insult-induced loss of neurons and myelin in the hippocampal region and neurobehavioral impairments, partially in a dose-dependent manner, and based on this, we determined the optimal drug concentration to be 50 mg/kg. Subsequent analysis found that this neuroprotective effect was achieved through the inhibition of HMGB1 expression and nucleocytoplasmic translocation, a reduction in the abnormal expression of proteins associated with the downstream signaling pathway of HMGB1, a decrease in the inflammatory response, the suppression of increases in microglia/astrocytes, and the inhibition of hippocampal cell apoptosis. Collectively, our discoveries contribute to the rising appreciation of the role of HMGB1 in the neuropathology of hippocampal dysfunction and related behavioral outcomes following HIBI.

Characterization of Ionic and Lipid Gradients within Corpus Callosum White Matter after Diffuse Traumatic Brain Injury in the Rat

There is increased recognition of the effects of diffuse traumatic brain injury (dTBI), which can initiate yet unknown biochemical cascades, resulting in delayed secondary brain degeneration and long-term neurological sequela. There is limited availability of therapies that minimize the effect of secondary brain damage on the quality of life of people who have suffered TBI, many of which were otherwise healthy adults. Understanding the cascade of biochemical events initiated in specific brain regions in the acute phase of dTBI and how this spreads into adjacent brain structures may provide the necessary insight into drive development of improved therapies. In this study, we have used direct biochemical imaging techniques (Fourier transform infrared spectroscopic imaging) and elemental mapping (X-ray fluorescence microscopy) to characterize biochemical and elemental alterations that occur in corpus callosum white matter in the acute phase of dTBI. The results provide direct visualization of differential biochemical and ionic changes that occur in the highly vulnerable medial corpus callosum white matter relative to the less vulnerable lateral regions of the corpus callosum. Specifically, the results suggest that altered ionic gradients manifest within mechanically damaged medial corpus callosum, potentially spreading to and inducing lipid alterations to white matter structures in lateral brain regions.

Role of quercetin and caloric restriction on the biomolecular composition of aged rat cerebral cortex: An FTIR study

Aging brain is characterized by a change in biomolecular composition leading to a diverse range of neurological diseases. Anti-aging research is of current interest, to lessen the burden of age-related macromolecular damage through antioxidant supplementation and caloric restriction. However, data concerning the effect of these anti-aging regimens on age-related biomolecular changes in rat brain is still lacking. In the present study, for the first time, we employed Fourier transform infrared (FTIR) spectroscopy, to investigate the effect of quercetin, caloric restriction (CR) and combination of both on alterations in the composition of lipids and proteins of aged rat brain cerebral cortex. Aged male Wistar rats (21 months old) were divided into four groups: Control (CONT), fed pellet diet; Quercetin (QUER), fed quercetin (50 mg/kg/day); CR (caloric restriction) (fed 40% reduced CONT), and CRQ (40% CR and 50 mg/kg/day QUER). Three-month-old rats served as young control (YOUNG). Our short-term study (45 days) shows decreased band area of unsaturated lipids, decreased area ratios of olefinic/lipid and CH₂ antisymmetric stretching (2925 cm^-1)/lipids in CONT group compared to young rats, suggesting age-associated lipid peroxidation in aged rats. A slight decrease in the frequency of CH₂ antisymmetric mode of lipids (whereas no change in CH₂ symmetric mode), but a decrease in bandwidths of both CH₂ antisymmetric and symmetric modes of lipids was observed for CONT group compared to YOUNG. Further, a significant decrease in the peak area of infrared bands of proteins and an increase in the peak area of the CO band of lipids was observed in the CONT group. Our data also show that lower levels of α-helical structures and higher levels of random coils, representing altered protein secondary structure composition in the CONT group compared to YOUNG group. Reduction in neuronal cell density and shrinked nucleus was also observed in aged rats. Increase in the accumulation of oxidative mediated damage to macromolecules and diminished antioxidant levels, could be the possible reason for the age-related alterations in the composition of lipids and proteins. However, the combination of quercetin and CR, but not either treatment alone, significantly prevented the age associated alterations in the lipid and protein profiles in the rat cerebral cortex. Further, our results help to understand the mechanism of action of antioxidants under non-restriction and CR conditions, this might help in the development of novel anti-aging treatments to ameliorate oxidative stress in age-related disorders.