Integrative Metabolic and Proteomic Profiling of the Brainstem in Spontaneously Hypertensive Rats

The role of 15 mA and 77.5 Hz transcranial alternating current stimulation in blood pressure regulation: A post hoc analysis of a randomized controlled trial

BACKGROUND

Transcranial alternating current stimulation (tACS) at 77.5 Hz and 15 mA, targeting the forehead and mastoid areas, has proven efficacious in patients with major depressive disorder (MDD) by simultaneously stimulating multiple brain nuclei and regions, many of which are critical for blood pressure regulation. This post hoc analysis aimed to assess the potential blood pressure-lowering effects of 77.5 Hz, 15 mA tACS in first-episode drug-naive MDD patients with normotension.

METHODS

Data from a previous randomized controlled trial (RCT) involving first-episode drug-naive MDD patients were analyzed. Participants underwent 20 sessions of either active tACS or sham stimulation. Vital signs, including systolic blood pressure (SBP) and diastolic blood pressure (DBP), were measured at baseline, after treatment (Week 4), and at follow-up (Week 8). Multivariate linear regression and Generalized Estimating Equations (GEE) models were used to evaluate the effects of the treatment on blood pressure.

RESULTS

Totally 68 participants were analysis (33 in the sham group and 35 in the active group). By Week 4, the active tACS group exhibited a significant reduction in both SBP and DBP compared to the sham group (coefficient - 2.04, 95 % CI -3.01 to -1.07, p < 0.001 on SBP, and coefficient - 1.92, 95 % CI -2.69 to -1.18, p < 0.001 on DBP).

CONCLUSIONS

tACS at 77.5 Hz and 15 mA can effectively reduce SBP and DBP in first-episode drug-naive depressive individuals with normotension, with greater reductions observed in those with higher baseline levels.

Genetic modulation of protein expression in rat brain

Genetic variations in protein expression are implicated in a broad spectrum of common diseases and complex traits but remain less explored compared to mRNA and classical phenotypes. This study systematically analyzed brain proteomes in a rat family using tandem mass tag (TMT)-based quantitative mass spectrometry. We quantified 8,119 proteins across two parental strains (SHR/Olalpcv and BN-Lx/Cub) and 29 HXB/BXH recombinant inbred (RI) strains, identifying 597 proteins with differential expression and 464 proteins linked to cis-acting quantitative trait loci (pQTLs). Proteogenomics identified 95 variant peptides, and sex-specific analyses revealed both shared and distinct cis-pQTLs. We improved the ability to pinpoint candidate genes underlying pQTLs by utilizing the rat pangenome and explored the connections between pQTLs in rats and human disorders. Collectively, this study highlights the value of large proteo-genetic datasets in elucidating protein modulation in the brain and its links to complex central nervous system (CNS) traits.

Acupuncture with twirling reinforcing and reducing manipulation shows a control of hypertension and regulation of blood pressure-related target brain regions in spontaneously hypertensive rat: a preliminary resting-state functional MRI study

Aim

To observe the effects of acupuncture manipulations on blood pressure and brain function in spontaneously hypertensive rats and elucidate the anti-hypertensive effect of the manipulations' central mechanism.

Methods

This study used acupuncture twirling reinforcing, acupuncture twirling reducing, and acupuncture twirling uniform reinforcing-reducing manipulations to act on the bilateral TaiChong point of rats. The depth of acupuncture was 1.5-2 mm, and twisting was performed at a frequency of 60 times/min within ±360° for 3 min, followed by the needle being retained for 17 min. Functional magnetic resonance imaging was performed at the end of the intervention. Regional homogeneity and amplitude of low-frequency fluctuations were used to assess the differences in brain regions in each group of rats, and the core brain region (left hypothalamus) among the differential brain regions was selected as the seed for functional connectivity analysis.

Results

(1) The anti-hypertensive effect was achieved by acupuncture manipulations, and the anti-hypertensive effect of twirling reducing manipulation on spontaneously hypertensive rats was better than that of twirling uniform reinforcing-reducing and twirling reinforcing manipulations. (2) After regional homogeneity and amplitude of low-frequency fluctuations analyses, the hypothalamus, the brain region related to blood pressure, was activated in the twirling uniform reinforcing-reducing manipulation group; the corpus callosum and cerebellum were activated in the twirling reinforcing manipulation group; and the hypothalamus, olfactory bulb, corpus callosum, brainstem, globus pallidum, and striatum were activated in the twirling reducing manipulation group. (3) According to the functional connectivity analysis, different acupuncture manipulations increased the functional connections between seed points and the brainstem, olfactory bulb, and cerebellum, etc.

Conclusion

These results suggest that acupuncture manipulations achieved the hypotensive effect and the twirling reducing manipulation had a better hypotensive effect on spontaneously hypertensive rats than twirling uniform reinforcing-reducing and twirling reinforcing manipulations; the central mechanism of the anti-hypertensive effect of twirling reinforcing and reducing manipulation may be related to the activation of brain regions associated with blood pressure regulation and the functional connections between them. Furthermore, brain regions involved in motor control, cognition, and hearing were also activated. We hypothesize that activation of these brain regions may help prevent or mitigate the onset and progression of hypertensive brain damage.

Potential antihypertensive mechanism of egg white-derived peptide QIGLF revealed by proteomic analysis

Previous work has shown that egg white-derived peptide QIGLF has significant in vivo antihypertensive activity. This study aimed to clarify the antihypertensive mechanisms of QIGLF on spontaneously hypertensive rats (SHRs) by a serum proteomic approach. Here, the tandem mass tag (TMT) quantitative proteomic was performed to discover serum protein changes in SHRs with QIGLF. As a result, SHRs with 4 weeks of QIGLF treatment have distinct serum protein expression profiles by principal component and Pearson's correlation coefficient analysis. Based on Gene Ontology (GO) annotation, oxygen transport and organelle fusion were found to be a regulated major biological process. Besides, aldosterone regulated sodium reabsorption, mitophagy, gap junction, and tight junction were significantly regulated based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. QIGLF might exert antihypertensive effects in the SHRs by inhibiting Na+ reabsorption and oxidative stress, restoring gap junction and tight junction.

Brain Bioenergetics in Chronic Hypertension: Risk Factor for Acute Ischemic Stroke

Chronic hypertension is one of the key modifiable risk factors for acute ischemic stroke, also contributing to determine greater neurological deficits and worse functional outcome when an acute cerebrovascular event would occur. A tight relationship exists between cerebrovascular autoregulation, neuronal activity and brain bioenergetics. In chronic hypertension, progressive adaptations of these processes occur as an attempt to cope with the demanding necessity of brain functions, creating a new steady-state homeostatic condition. However, these adaptive modifications are insufficient to grant an adequate response to possible pathological perturbations of the established fragile hemodynamic and metabolic homeostasis. In this narrative review, we will discuss the main mechanisms by which alterations in brain bioenergetics and mitochondrial function in chronic hypertension could lead to increased risk of acute ischemic stroke, stressing the interconnections between hemodynamic factors (i.e. cerebral autoregulation and neurovascular coupling) and metabolic processes. Both experimental and clinical pieces of evidence will be discussed. Moreover, the potential role of mitochondrial dysfunction in determining, or at least sustaining, the pathogenesis and progression of chronic neurogenic hypertension will be considered. In the perspective of novel therapeutic strategies aiming at improving brain bioenergetics, we propose some determinant factors to consider in future studies focused on the cause-effect relationships between chronic hypertension and brain bioenergetic abnormalities (and vice versa), so to help translational research in this so-far unfilled gap.

Identification of novel proteins and mechanistic pathways associated with early-onset hypertension by deep proteomic mapping of resistance arteries

Resistance arteries are small blood vessels that create resistance to blood flow. In hypertension, resistance arteries undergo remodeling, affecting their ability to contract and relax appropriately. To date, no study has mapped the hypertension-related proteomic changes in resistance arteries. Using a novel data-independent acquisition–mass spectrometry (DIA-MS) approach, we determined the proteomic changes in small mesenteric and renal arteries in pre- and early-onset hypertension from the spontaneously hypertensive rat (SHR) model, which represents human primary hypertension. Compared with normotensive controls, mesenteric arteries from 12-week-old SHRs had 286 proteins that were significantly up- or downregulated, whereas 52 proteins were identified as up- or downregulated in mesenteric arteries from 6-week-old SHRs. Of these proteins, 18 were also similarly regulated in SHR renal arteries. Our pathway analyses reveal several novel pathways in the pathogenesis of hypertension. Finally, using a matrisome database, we identified 38 altered extracellular-matrix-associated proteins, many of which have never previously been associated with hypertension. Taken together, this study reveals novel proteins and mechanisms that are associated with early-onset hypertension, thereby providing novel insights into disease progression.

Metabolic Profiling Revealed Prediction Biomarkers for Infantile Hemangioma in Umbilical Cord Blood Sera: A Prospective Study

Infantile hemangioma (IH), the most common benign tumor in infancy, mostly arises and has rapid growth before 3 months of age. Because irreversible skin changes occur in the early proliferative stage, early medical treatment is essential to reduce the permanent sequelae caused by IH. Yet there are still no early screening biomarkers for IH before its visible emergence. This study aimed to explore prediction biomarkers using noninvasive umbilical cord blood (UCB). A prospective study of the metabolic profiling approach was performed on UCB sera from 28 infants with IH and 132 matched healthy controls from a UCB population comprising over 1500 infants (PeptideAtlas: PASS01675) using liquid chromatography-mass spectrometry. The metabolic profiling results exhibited the characteristic metabolic aberrance of IH. Machine learning suggested a panel of biomarkers to predict the occurrence of IH, with the area under curve (AUC) values in the receiver operating characteristic analysis all >0.943. Phenylacetic acid had potential to predict infants with large IH (diameter >2 cm) from those with small IH (diameter <2 cm), with an AUC of 0.756. The novel biomarkers in noninvasive UCB sera for predicting IH before its emergence might lead to a revolutionary clinical utility.

Targeted Metabolic Profiling and PRM Analysis of Proteins Revealed Impaired Polyunsaturated Fatty Acid Metabolism and GTP Metabolism in the Brainstem of Spontaneously Hypertensive Rats

An untargeted multi-omics study implicated the potential dysregulation of fatty acid, nucleotide, and energy metabolism in the brainstems of spontaneously hypertensive rats (SHRs). A further quantitative exploration of the alterations in the metabolic pathways is necessary for a deep understanding of the central nervous system in SHRs. Targeted metabolic profiling of 40 fatty acids (PeptideAtlas: PASS01671) and 32 metabolites of nucleotides and energy metabolism (PeptideAtlas: PASS01672) and parallel reaction monitoring analysis of 5 proteins (PeptideAtlas: PASS01673) were performed on the brainstems of SHRs (n = 8, 11 weeks old) and normotensive Wistar rats (n = 8, age-matched) using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem MS. The targeted profiling results of metabolites and proteins revealed decreased polyunsaturated fatty acid (PUFA) synthesis with a significant downregulation of cis-11,14-eicosadienoic acid, cis-13,16-docosadienoic acid, and docosatetraenoate and impaired PUFA oxidation with the accumulation of γ-linolenate induced by the significantly downregulated expression of 2,4-dienoyl-CoA reductase (p < 0.05). Dysregulated GTP and ATP metabolism was observed, with significantly decreased GDP and ADP (p < 0.05) correlated with reduced GTPases of guanine nucleotide-binding protein subunit beta-1 (GNB1), transforming protein RhoA (RHOA), and Rho-related GTP-binding protein RhoB (RHOB) in the brainstem of SHRs. In addition, protein-arginine deiminase type-2 was significantly reduced in the brainstems of SHRs (p < 0.05). The aberrant PUFA and energy metabolism might help to explain the alterations in the brainstem of SHRs. The findings on both metabolites and proteins could provide systemic insights into the pathology basis of altered PUFA and energy metabolism in hypertension, especially in the central nervous system.

Integrative Analysis of Metabolomic and Transcriptomic Data Reveals Metabolic Alterations in Glioma Patients

Glioma is a malignant brain tumor. There is growing evidence that its progression involves altered metabolism. This study's objective was to understand how those metabolic perturbations were manifested in plasma and urine. Metabolic signatures in blood and urine were characterized by liquid chromatography-tandem mass spectrometry. The results were linked to gene expression using data from the Gene Expression Omnibus database. Genes and pathways associated with the disease were thus identified. Forty metabolites were identified, which were differentially expressed in the plasma of glioma patients, and 61 were identified in their urine. Twenty-two metabolites and five disturbed pathways were found both in plasma and urine. Twelve metabolites in plasma and three in urine exhibited good diagnostic potential for glioma. Transcriptomic analyses revealed specific changes in the expression of 1437 genes associated with glioma. Seventeen differentially expressed genes were found to be correlated with four of the metabolites. Enrichment analysis indicated that dysregulation of glutamatergic synapse pathway might affect the pathology of glioma. Integration of metabolomics with transcriptomics can provide both a broad picture of novel cancer signatures and preliminary information about the molecular perturbations underlying glioma. These results may suggest promising targets for developing effective therapies.