[Effects and mechanisms of negative air ions on blood pressure, oxidative stress and inflammation levels in SHR rats].

OBJECTIVE: To investigate the effects and possible mechanisms of negative air ions(NAIs) on blood pressure, oxidative stress, and inflammatory status in spontaneous hypertension rats(SHR). METHODS: A total of 60 SHR(half male and half female) were randomly divided into one-month and three-month groups, 30 rats per groups, based on the duration of the intervention. Each group was further randomized into three groups based on the daily intervention time: SHR control group, 2 h NAIs-SHR group, and 6 h NAIs-SHR group, 10 rats per groups. In addition, 20 Wistar Kyoto(WKY)(half male and half female), were randomized into one-month WKY group and three-month WKY group, 10 rats per groups, based on the intervention time. The 2 h NAIs-SHR group and 6 h NAIs-SHR group were exposed to an environment with NAIs concentrations of 4.5×10~4-5×10~4 cm~3 per day for 2 h and 6 h. The WKY group and SHR group were exposed to normal air on a daily basis. Blood pressure of rats in each group was measured every three days, while weight was measured once a week. After sacrificing the rats in the first month and the third month of rearing, wet weight of the organs was weighed. The enzyme linked immunosorbent assay(ELISA) was used to detect 8-hydroxylated deoxyguanosine(8-OHdG), interleukin-6(IL-6), interleukin-8(IL-8), tumor necrosis factor-α(TNF-α), nitric oxide(NO) and endothelin-1(ET-1) levels. Reactive oxygen species(ROS) detection kit was used to detect ROS level. Malondialdehyde(MDA) and superoxide dismutase(SOD), glutathione(GSH) and glutathione disulfide(GSSG) were measured by colorimetric analysis. HE staining was conducted to observe the histopathological morphological changes of the thoracic aorta in each group, and Western blot was conducted to detect the thoracic aortap38 mitogen-activated protein kinase(p38 MAPK), extracellular signal-regulated kinases(ERK), c-Jun n-terminal kinase(JNK), c-fos proteins, c-jun proteins and their phosphorylated proteins level. RESULTS: The weight of WKY male mice in the same week age group was higher than that of SHR control group, and there was no significant difference in the weight between the other groups. The coefficient of heart in SHR control group(4.66±0.48) was higher than that in WKY group(3.73±0.15)(P<0.05), while there were no significant differences in the coefficients of brain, kidney, liver and spleen among the groups. Blood pressure in WKY group at the same age was lower than that in SHR group, and blood pressure in SHR control group at 2-5 and 8-11 weeks was higher than that in 2 h NAIs-SHR and 6 h NAIs-SHR groups(P<0.05). HE staining showed that the internal, middle and external membranes of thoracic aorta in 2 h NAIs-SHR group and 6 h NAIs-SHR group were improved to varying degrees compared with those in SHR control group, including disordered internal membrane structure, thickened middle membrane and broken external membrane. In terms of oxidative stress levels, compared with the SHR control group, the ROS(0.66%±0.17%, 0.49%±0.32%) and 8-OHdG((48.29±8.00) ng/mL, (33.13±14.67)ng/mL) levels were lower in the 6 h NAIs-SHR group(P<0.05), while the GSH/GSSG ratio was higher in the one-month 6 h NAIs-SHR group(10.08±4.93). Compared with the 2 h NAIs-SHR group, the ROS level(0.99%±0.19%) was lower in the 6 h NAIs-SHR group(P<0.05). In terms of inflammatory factor levels, compared with the SHR control group, the IL-8 levels((160.44±56.54) ng/L, (145.77±38.39) ng/L) were lower in the 6 h NAIs-SHR group(P<0.05), while the ET-1 level((249.55±16.98) ng/L) was higher in the one-month WKY group. There was no significant difference in NO levels among the groups. The relative expression of p-p38 protein in the thoracic aorta of rats in the one-month SHR control group was lower than that in the WKY group(P<0.05). The relative expression of p-p38 and p-c-fos proteins in the thoracic aorta of rats at three-months was higher in the SHR control group than in the 2 h NAIs-SHR and 6 h NAIs-SHR groups(P<0.05). CONCLUSION: The intervention of NAIs at a concentration of 4.5×10~4-5×10~4/cm~3 may regulate the partial oxidation and inflammatory state of SHR rats through the ROS/MAPK/AP1 signaling pathway, thereby reducing their blood pressure level.

Changes in cardiovascular autonomic control induced by chronic inhibition of acetylcholinesterase during pyridostigmine or donepezil treatment of spontaneously hypertensive rats.

Chronic treatment with acetylcholinesterase inhibitors may be a promising therapeutic strategy for treatment of cardiovascular diseases. The aim of our study was to analyze the changes in blood pressure (BP) and heart rate (HR) during 14 days of treatment with two different acetylcholinesterase inhibitors - pyridostigmine (PYR) having only peripheral effects or donepezil (DON) with both peripheral and central effects. In addition, we studied their effects on the cardiovascular response to restraint stress and on sympathovagal control of HR in normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). SHR were characterized by elevated BP and increased low-frequency component of systolic BP variability (LF-SBPV), but their cardiac vagal tone and HR variability (HRV) were reduced compared with WKY. Chronic treatment with either acetylcholinesterase inhibitor decreased HR and increased HRV in both strains. PYR treatment slightly decreased BP and LF-SBPV in the dark phase of the day. Neither drug significantly altered BP response to stress, but PYR attenuated HR increase during restraint stress. Regarding sympathovagal balance, acute methylatropine administration caused a greater increase of HR in WKY than in SHR. Chronic PYR or DON treatment enhanced HRV and HR response to methylatropine (vagal tone) in WKY, whereas PYR but not DON treatment potentiated HRV and vagal tone in SHR. In conclusion, vagal tone was lower in SHR compared with WKY, but was enhanced by chronic PYR treatment in both strains. Thus, chronic peripheral, but not central, acetylcholinesterase inhibition has major effects on HR and its variability in both normotensive and hypertensive rats.

Meteorin-like (METRNL) attenuates hypertensive induced cardiac hypertrophy by inhibiting autophagy via activating BRCA2.

Hypertension, a prevalent cardiovascular ailment globally, can precipitate numerous complications, notably hypertensive cardiomyopathy. Meteorin-like (METRNL) is demonstrated to possess potential protective properties on cardiovascular diseases. However, its specific role and underlying mechanism in hypertensive myocardial hypertrophy remain elusive. Spontaneously hypertensive rats (SHRs) served as hypertensive models to explore the effects of METRNL on hypertension and its induced myocardial hypertrophy. The research results indicate that, in contrast to Wistar-Kyoto (WKY) rats, SHRs exhibit significant symptoms of hypertension and myocardial hypertrophy, but cardiac-specific overexpression (OE) of METRNL can partially ameliorate these symptoms. In H9c2 cardiomyocytes, METRNL suppresses Ang II-induced autophagy by controlling the BRCA2/Akt/mTOR signaling pathway. But when BRCA2 expression is knocked down, this effect will be suppressed. Collectively, METRNL emerges as a potential therapeutic target for hypertensive cardiomyopathy.

The protective effects of Irbesartan in cognitive impairment in hypertension.

Vascular cognitive impairment (VCI) is claimed as the second most common type of dementia after Alzheimer's disease (AD), in which hypertension is a critical inducer. Currently, hypertension-induced cognitive impairment lacks clinical treatments. Irbesartan is a long-acting angiotensin receptor antagonist with promising antihypertensive properties. Our research will focus on the potential function of Irbesartan on hypertension-induced cognitive impairment. Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats were orally dosed with normal saline or 20 mg/kg/day Irbesartan for 14 consecutive days, with 4 groups divided shown as below: WKY, Irbesartan, SHR, SHR+ Irbesartan. Firstly, the markedly increased systolic blood pressure observed in SHR rats was signally repressed by Irbesartan on Day 7 and 14 post-dosing. Moreover, notably decreased time of exploring the novel object in the object recognition task (ORT) test, elevated escape latency, and reduced time in the target quadrant in the Morris water maze (MWM) test were observed in SHR rats, which were prominently reversed by Irbesartan. Furthermore, the declined superoxide dismutase (SOD) activity, elevated malondialdehyde (MDA) level, increased cyclin-dependent kinase-5 (CDK5) activity, and enhanced protein level of p35/p25, p-Tau (pSer214)/Tau46, and brain-derived neurotrophic factor (BDNF) were memorably rescued by Irbesartan. Lastly, the activity of cAMP/cAMP response element binding protein (CREB) signaling in the hippocampus of SHR rats was markedly repressed, accompanied by an upregulation of phosphodiesterase 4B (PDE4B), which was observably rescued by Irbesartan. Collectively, Irbesartan protected against the hypertension-induced cognitive impairment in SHR rats by regulating the cAMP/CREB signaling.

Influence of a Decrease in Blood Viscosity on Arterial Pressure in Normotensive and Spontaneously Hypertensive Rats.

We investigated the effect of a decrease in blood viscosity on the mean BP during isovolumic hemodilution and vasodilating activity of the endothelium in normotensive Wistar rats and spontaneously hypertensive rats (SHR). Blood viscosity was reduced by isovolumic hemodilution (replacement of 10% of circulating blood with an equal volume of plasma). Hemodilution caused the same reduction in blood viscosity by 16% in both groups of rats. In Wistar rats, a decrease in blood viscosity did not significantly change in the mean BP; no significant correlations between blood viscosity and mean BP were observed before and after hemodilution. In SHR, a decrease in blood viscosity led to a significant decrease in the mean BP by 18%. Correlations were found between the mean BP and blood viscosity in SHR before (r=0.63; p=0.028) and after (r=0.71; p=0.009) isovolumic hemodilution. In SHR, a decrease in the index of vasodilating activity of the endothelium due to a decrease in the vasodilatory response to intravenous administration of the endothelium-dependent vasodilator acetylcholine was revealed. In SHR, BP passively follows the change, in this case, the decrease in blood viscosity, which attests to impaired BP regulation in response to changes in shear stress on the vascular endothelium caused by the development of endothelial dysfunction in hypertensive animals.

Modulation of TNF-α, interleukin-6, and interleukin-10 by nebivolol-valsartan and nebivolol-lisinopril polytherapy in SHR rats.

Antihypertensive drug therapies have demonstrated their capacity to modulate the inflammatory processes associated with hypertension, leading to improvements in disease progression. Given the prevalent use of polytherapy in treating most hypertensive patients, comprehending the time-dependent effects of combination treatments on inflammation becomes imperative. In this study, spontaneously hypertensive rats (SHR) were divided into seven groups (n = 6): (i) SHR + vehicle, (ii) SHR + nebivolol, (iii) SHR + valsartan, (iv) SHR + lisinopril, (v) SHR + nebivolol-valsartan, (vi) SHR + nebivolol-lisinopril, and (vii) WKY + vehicle. Blood pressure was measured using the tail-cuff method. Temporal alterations in inflammatory cytokines TNF-α, IL-6, and IL-10 were assessed in serum through ELISA and mRNA expression in aortic tissue via qPCR after 1, 2, and 4 weeks of treatment with nebivolol, lisinopril, valsartan, and their respective combinations. Histological alterations in the aorta were assessed. The findings indicated that combined treatments reduced systolic and diastolic blood pressure in SHR. The nebivolol and lisinopril combination demonstrated a significant decrease in IL-6 serum and mRNA expression at both 1 week and 4 weeks into the treatment. Additionally, TNF-α mRNA expression also showed a reduction with this combination at the same time points. Particularly, nebivolol-valsartan significantly decreased TNF-α serum and mRNA expression after one and four weeks of treatment. Furthermore, an elevation in serum IL-10 levels was observed with both combination treatments starting from the second week onwards. This study provides compelling evidence that concurrent administration of nebivolol with lisinopril or valsartan exerts time-dependent effects, reducing proinflammatory cytokines TNF-α and IL-6 while modifying IL-10 levels in an experimental hypertensive model.

A Novel Rat Model of Mild Pulmonary Hypertension Associated with Pulmonary Venous Congestion Induced by Left Pulmonary Vein Banding.

Pulmonary hypertension (PH) associated with left heart disease (PH-LHD) is the most common form of PH. In PH-LHD, changes in the pulmonary vasculature are assumed to be mainly caused by pulmonary venous congestion. However, the underlying mechanisms of this form of PH are poorly understood. We aimed to establish a model of PH associated with pulmonary venous congestion. Wistar-Kyoto rats underwent partial occlusion of the left pulmonary vein to induce pulmonary venous congestion or sham surgery and were assessed at various time points post-surgery (3, 6, 9, 12 weeks). In vivo cardiopulmonary phenotyping was performed by using echocardiography along with heart catheterization. Histomorphometry methods were used to assess pulmonary vascular remodeling (e.g., wall thickness, degree of muscularization). Left pulmonary vein banding (PVB) resulted in mildly elevated right ventricular systolic pressure and moderate right ventricular hypertrophy. In PVB rats, small- and medium-sized pulmonary vessels in the left lung were characterized by increased wall thickness and muscularization. Taken together, our data demonstrate that left PVB-induced pulmonary venous congestion is associated with pulmonary vascular remodeling and mild PH.

Chronic mild stress-induced dysregulation of MAPK and PI3K/AKT signaling in the hippocampus and medial prefrontal cortex of WKY female rats.

Wistar-Kyoto (WKY) rats subjected to chronic mild stress (CMS) represent a valid model of treatment-resistant depression (TRD). Considering that depression is more prevalent in women than in men, in the present study, female rats were used. We investigated the effect of CMS on behavior and different factors involved in neuroinflammatory processes and neuroplasticity in the hippocampus and medial prefrontal cortex (mPFC) of WKY female rats. The results show that unstressed WKY females exhibited hypolocomotion, decreased exploratory behavior, and an increase in the total grooming time. After exposure to CMS, WKY females displayed intensified grooming. To investigate potential neural mechanisms underlying these behavioral changes, we analyzed signaling and inflammatory pathways in the hippocampus and mPFC. The findings indicate reduced BDNF and elevated levels levels of IL-1ß in both brain structures and NLRP3 in the mPFC of unstressed WKY female rats. WKY rats subjected to CMS showed a further decrease in BDNF levels and increased IL-1ß and NLRP3 in these brain structures. WKY showed reduced pERK1/2 and increased pp38 levels in both brain structures, while CMS revealed a further increase of pp38 in WKY in these brain structures. Expressions of p110ß and pAKT were decreased in the hippocampus and mPFC of WKY rats. The CMS further suppressed p110 and the downstream AKT phosphorylation in the hippocampus, but did not affect the p110 and pAKT in the mPFC. Our findings indicate behavioral and molecular differences in genetically vulnerable WKY female rats and in their response to CMS that may be involved in TRD.

The WMI Rat of Premature Cognitive Aging Presents Intrinsic Vulnerability to Oxidative Stress in Primary Neurons and Astrocytes Compared to Its Nearly Isogenic WLI Control.

The primary neuronal and astrocyte culture described here is from the stress-hyperreactive Wistar Kyoto (WKY) More Immobile (WMI) rat with premature aging-related memory deficit, and its nearly isogenic control, the Less Immobile (WLI) strain. Primary WMI hippocampal neurons and cortical astrocytes are significantly more sensitive to oxidative stress (OS) generated by administration of H2O2 compared to WLI cells as measured by the trypan blue cell viability assay. Intrinsic genetic vulnerability is also suggested by the decreased gene expression in WMI neurons of catalase (Cat), and in WMI cortical astrocytes of insulin-like growth factor 2 (Igf2), synuclein gamma (Sncg) and glutathione peroxidase 2 (Gpx2) compared to WLI. The expressions of several mitochondrial genes are dramatically increased in response to H2O2 treatment in WLI, but not in WMI cortical astrocytes. We propose that the vulnerability of WMI neurons to OS is due to the genetic differences between the WLI and WMI. Furthermore, the upregulation of mitochondrial genes may be a compensatory response to the generation of free radicals by OS in the WLIs, and this mechanism is disturbed in the WMIs. Thus, this pilot study suggests intrinsic vulnerabilities in the WMI hippocampal neurons and cortical astrocytes, and affirm the efficacy of this bimodal in vitro screening system for finding novel drug targets to prevent oxidative damage in illnesses.

Premotor projections from the locus coeruleus and periaqueductal grey are altered in two rat models with inborn differences in emotional behavior.

Emotionally motivated behaviors rely on the coordinated activity of descending neural circuits involved in motor and autonomic functions. Using a pseudorabies (PRV) tract-tracing approach in typically behaving rats, our group previously identified descending premotor, presympathetic, and dual-labeled premotor-presympathetic populations throughout the central rostral-caudal axis. The premotor-presympathetic populations are thought to integrate somatomotor and sympathetic activity. To determine whether these circuits are dysregulated in subjects with altered emotional regulation, subsequent neuroanatomical analyses were performed in male subjects of two distinct genetic models relevant to clinical depression and anxiety: the Wistar Kyoto (WKY) rat and selectively bred Low Novelty Responder (bLR) rat. The present study explored alterations in premotor efferents from locus coeruleus (LC) and subdivisions of the periaqueductal grey (PAG), two areas involved in emotionally motivated behaviors. Compared to Sprague Dawley rats, WKY rats had significantly fewer premotor projections to hindlimb skeletal muscle from the LC and from the dorsomedial (DMPAG), lateral (LPAG), and ventrolateral (VLPAG) subdivisions of PAG. Relative to selectively bred High Novelty Responder (bHR) rats, bLR rats had significantly fewer premotor efferents from LC and dorsolateral PAG (DLPAG). Cumulatively, these results demonstrate that somatomotor circuitry in several brain areas involved in responses to stress and emotional stimuli are altered in rat models with depression-relevant phenotypes. These somatomotor circuit differences could be implicated in motor-related impairments in clinically depressed patients.

Phasic dopamine signals are reduced in the spontaneously hypertensive rat and increased by methylphenidate.

The spontaneously hypertensive rat (SHR) is a selectively bred animal strain that is frequently used to model attention-deficit hyperactivity disorder (ADHD) because of certain genetically determined behavioural characteristics. To test the hypothesis that the characteristically altered response to positive reinforcement in SHRs may be due to altered phasic dopamine response to reward, we measured phasic dopamine signals in the SHRs and Sprague Dawley (SD) rats using in vivo fast-scan cyclic voltammetry. The effects of the dopamine reuptake inhibitor, methylphenidate, on these signals were also studied. Phasic dopamine signals during the pairing of a sensory cue with electrical stimulation of midbrain dopamine neurons were significantly smaller in the SHRs than in the SD rats. Over repeated pairings, the dopamine response to the sensory cue increased, whereas the response to the electrical stimulation of dopamine neurons decreased, similarly in both strains. However, the final amplitude of the response to the sensory cue after pairing was significantly smaller in SHRs than in the SD rats. Methylphenidate increased responses to sensory cues to a significantly greater extent in the SHRs than in the SD rats, due largely to differences in the low dose effect. At a higher dose, methylphenidate increased responses to sensory cues and electrical stimulation similarly in SHRs and SD rats. The smaller dopamine responses may explain the reduced salience of reward-predicting cues previously reported in the SHR, whereas the action of methylphenidate on the cue response suggests a potential mechanism for the therapeutic effects of low-dose methylphenidate in ADHD.

Effects of Gestational Exercise on Nociception, BDNF, and Irisin Levels in an Animal Model of ADHD.

Abnormal cognitive and sensorial properties have been reported in patients with psychiatric and neurodevelopmental conditions, such as attention deficit hyperactivity disorder (ADHD). ADHD patients exhibit impaired dopaminergic signaling and plasticity in brain areas related to cognitive and sensory processing. The spontaneous hypertensive rat (SHR), in comparison to the Wistar Kyoto rat (WKY), is the most used genetic animal model to study ADHD. Brain neurotrophic factor (BDNF), critical for midbrain and hippocampal dopaminergic neuron survival and differentiation, is reduced in both ADHD subjects and SHR. Physical exercise (e.g. swimming) promotes neuroplasticity and improves cognition by increasing BDNF and irisin. Here we investigate the effects of gestational swimming on sensorial and behavioral phenotypes, striatal dopaminergic parameters, and hippocampal FNDC5/irisin and BDNF levels observed in WKY and SHR. Gestational swimming improved nociception in SHR rats (p = 0.006) and increased hippocampal BDNF levels (p = 0.02) in a sex-dependent manner in adolescent offspring. Sex differences were observed in hippocampal FNDC5/irisin levels (p = 0.002), with females presenting lower levels than males. Our results contribute to the notion that swimming during pregnancy is a promising alternative to improve ADHD phenotypes in the offspring.

Limited WKY chromosomal regions confer increases in anxiety and fear memory in a F344 congenic rat strain.

This study investigated the interaction between genetic differences in stress reactivity/coping and environmental challenges, such as acute stress during adolescence on adult contextual fear memory and anxiety-like behaviors. Fischer 344 (F344) and the inbred F344;WKY-Stresp3/Eer congenic strain (congenic), in which chromosomal regions from the Wistar-Kyoto (WKY) strain were introgressed into the F344 background, were exposed to a modified forced swim test during adolescence, while controls were undisturbed. In adulthood, fear learning and memory, assessed by contextual fear conditioning, were significantly greater in congenic animals compared with F344 animals, and stress during adolescence increased them even further in males of both strains. Anxiety-like behavior, measured by the open field test, was also greater in congenic than F344 animals, and stress during adolescence increased it further in both strains of adult males. Whole genome sequencing of the F344;WKY-Stresp3/Eer strain revealed an enrichment of WKY genotypes in chromosomes 9, 14, and 15. An example of functional WKY sequence variations in the congenic strain, cannabinoid receptor interacting protein 1 (Cnrip1) had a Cnrip1 transcript isoform that lacked two exons. Although the original hypothesis that the genetic predisposition to increased anxiety of the WKY donor strain would exaggerate fear memory relative to the background strain was confirmed, the consequences of adolescent stress were strain independent but sex dependent in adulthood. Molecular genomic approaches combined with genetic mapping of WKY sequence variations in chromosomes 9, 14, and 15 could aid in finding quantitative trait genes contributing to the variation in fear memory.NEW & NOTEWORTHY This study found that 1) whole genome sequencing of congenic strains should be a criterion for their recognition; 2) sequence variations between Wistar-Kyoto and Fischer 344 strains at regions of chromosomes 9, 14, and 15 contribute to differences in contextual fear memory and anxiety-like behaviors; and 3) stress during adolescence affects these behaviors in males, but not females, and is independent of strain.

Validation of Wistar-Kyoto rats kept in solitary housing as an animal model for depression using voxel-based morphometry.

Major depressive disorder is a common psychiatric condition often resistant to medication. The Wistar-Kyoto (WKY) rat has been suggested as an animal model of depression; however, it is still challenging to translate results from animal models into humans. Solitary housing is a mild stress paradigm that can simulate the environment of depressive patients with limited social activity due to symptoms. We used voxel-based morphometry to associate the solitary-housed WKY (sWKY) rat model with data from previous human studies and validated our results with behavioural studies. As a result, atrophy in sWKY rats was detected in the ventral hippocampus, caudate putamen, lateral septum, cerebellar vermis, and cerebellar nuclei (p < 0.05, corrected for family-wise error rate). Locomotor behaviour was negatively correlated with habenula volume and positively correlated with atrophy of the cerebellar vermis. In addition, sWKY rats showed depletion of sucrose consumption not after reward habituation but without reward habituation. Although the application of sWKY rats in a study of anhedonia might be limited, we observed some similarities between the regions of brain atrophy in sWKY rats and humans with depression, supporting the translation of sWKY rat studies to humans.

Serotonergic and Adrenergic Neuroreceptor Manipulation Ameliorates Core Symptoms of ADHD through Modulating Dopaminergic Receptors in Spontaneously Hypertensive Rats.

The core symptoms of attention deficit hyperactivity disorder (ADHD) are due to the hypofunction of the brain's adrenergic (NE) and dopamine (DA) systems. Drugs that enhance DA and NE neurotransmission in the brain by blocking their transporters or receptors are the current therapeutic strategies. Of late, the emerging results point out the serotonergic (5-HT) system, which indirectly modulates the DA activity in reducing the core symptoms of ADHD. On this basis, second-generation antipsychotics, which utilize 5-HT receptors, were prescribed to children with ADHD. However, it is not clear how serotonergic receptors modulate the DA activity to minimize the symptoms of ADHD. The present study investigates the efficacy of serotonergic and alpha-2 adrenergic receptor manipulation in tackling the core symptoms of ADHD and how it affects the DA neuroreceptors in the brain regions involved in ADHD. Fifteen-day-old male spontaneously hypertensive rats (SHRs) received 5-HT1A agonist (ipsapirone) or 5-HT2A antagonist (MDL 100907) (i.p.) or alpha-2 agonist (GFC) from postnatal days 15 to 42 along with age-matched Wistar Kyoto rats (WKY) (n = 8 in each group). ADHD-like behaviors were assessed using a battery of behavioral tests during postnatal days 44 to 65. After the behavioral tests, rat brains were processed to estimate the density of 5-HT1A, 5-HT2A, DA-D1, and DA-D2 neuroreceptors in the prefrontal cortex, the striatum, and the substantia nigra. All three neuroreceptor manipulations were able to minimize the core symptoms of ADHD in SHRs. The positive effect was mainly associated with the upregulation of 5-HT2A receptors in all three areas investigated, while 5-HT1A was in the prefrontal cortex and the substantia nigra. Further, the DA-D1 receptor expression was downregulated by all three neuroreceptor manipulations except for alpha-2 adrenergic receptor agonists in the striatum and 5-HT2A antagonists in the substantia nigra. The DA-D2 expression was upregulated in the striatum while downregulated in the prefrontal cortex and the substantia nigra. In this animal model study, the 5-HT1A agonist or 5-HT2A antagonist monotherapies were able to curtail the ADHD symptoms by differential expression of DA receptors in different regions of the brain.

Mesenteric artery smooth muscle cells from hypertensive rats have increased microtubule acetylation.

The dynamic nature of the microtubule network is dependent in part by post-translational modifications (PTMs) - particularly through acetylation, which stabilizes the microtubule network. Whether PTMs of the microtubule network in vascular smooth muscle cells (VSMCs) contribute to the pathophysiology of hypertension is unknown. The aim of this study was to determine the acetylated state of the microtubule network in the mesenteric arteries of spontaneously hypertensive rats (SHR). Experiments were performed on male normotensive rats and SHR mesenteric arteries. Western blotting and mass spectrometry determined changes in tubulin acetylation. Wire myography was used to investigate the effect of tubacin on isoprenaline-mediated vasorelaxations. Isolated cells from normotensive rats were used for scanning ion conductance microscopy (SICM). Mass spectrometry and Western blotting showed that tubulin acetylation is increased in the mesenteric arteries of the SHR compared with normotensive rats. Tubacin enhanced the ß-adrenoceptor-mediated vasodilatation by isoprenaline when the endothelium was intact, but attenuated relaxations when the endothelium was denuded or nitric oxide production was inhibited. By pre-treating vessels with colchicine to disrupt the microtubule network, we were able to confirm that the effects of tubacin were microtubule-dependent. Using SICM, we examined the cell surface Young's modulus of VSMCs, but found no difference in control, tubacin-treated, or taxol-treated cells. Acetylation of tubulin at Lys40 is elevated in mesenteric arteries from the SHR. Furthermore, this study shows that tubacin has an endothelial-dependent bimodal effect on isoprenaline-mediated vasorelaxation.

Chronic Intermittent Hypobaric Hypoxia Reduces Hypothalamic N-Methyl-d-Aspartate Receptor Activity and Sympathetic Outflow in Spontaneously Hypertensive Rats.

Guo, Xinqi, Hongyu Ma, Ziye Cui, Qiyue Zhao, Ying Zhang, Lu Jia, Liping Zhang, Hui Guo, Xiangjian Zhang, Yi Zhang, Yue Guan, and Huijie Ma. Chronic intermittent hypobaric hypoxia reduces hypothalamic N-Methyl-d-Aspartate Receptor activity and sympathetic outflow in spontaneously hypertensive rats. High Alt Med Biol. 25:77-88, 2024. Objective: This study aims to determine the role of hypothalamic renin-angiotensin system (RAS) in the antihypertensive effect of chronic intermittent hypobaric hypoxia (CIHH). Methods: Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs) received 35 days of hypobaric hypoxia simulating an altitude of 4,000 m, 5 h/day. The levels of RAS, blood pressure, and N-methyl-d-aspartate receptor (NMDAR) activities of hypothalamic paraventricular nucleus (PVN) presympathetic neurons from each group of rats were determined. Results: The systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure (MAP) of SHRs significantly decreased from the third week of CIHH treatment. This blood pressure reduction effect could be maintained for at least 2 weeks after stopping the CIHH treatment. CIHH treatment also attenuated the decrease in MAP and renal sympathetic nerve activity induced by hexamethonium administration in SHRs, but not in WKY rats. Furthermore, CIHH reversed the increase in serum angiotensin (Ang)II concentration and the expression of PVN angiotensin-converting enzyme (ACE) and AngII type 1 (AT1) receptors, as well as the decrease in serum Ang1-7 concentration and the expression of PVN ACE2 and Mas receptors in SHRs. In addition, the administration of CIHH resulted in a reduction in the frequency of miniature excitatory postsynaptic currents and amplitude of NMDAR current in PVN presympathetic neurons of SHRs, which means that CIHH decreased the pre- and postsynaptic NMDAR activity of PVN presympathetic neurons in SHRs. However, pretreatment with A779 (a Mas receptor blocker) or AngII abrogated the above effects. Meanwhile, Ang1-7 pretreatment mimicked the CIHH effect on pre- and postsynaptic NMDAR activity of presympathetic neurons in SHRs. Conclusions: Our data indicate that CIHH reduces pre- and postsynaptic NMDAR activity of PVN presympathetic neurons, sympathetic outflow, and blood pressure by decreasing the activity of the ACE/AngII/AT1 axis and increasing the activity of ACE2/Ang1-7/Mas axis in the hypothalamus in hypertension.

Integrated analysis reveals ceRNA network of cardiac remodeling by SGLT2 inhibitor in middle-aged hypertensive rats.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) represent an innovative class of antidiabetic agents that have demonstrated promise in mitigating cardiac remodeling. However, the transcriptional regulatory mechanisms underpinning their impact on blood pressure and the reversal of hypertension-induced cardiac remodeling remain largely unexplored. Given this context, our study concentrated on comparing the cardiac expression profiles of lncRNAs and mRNAs between Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). To validate our results, we performed blood pressure measurements, tissue staining, and qRT-PCR. The treatment led to a significant reduction in systolic blood pressure and improved cardiac remodeling by reducing myocardial fibrosis and regulating the inflammatory response. Our examination disclosed that ventricular tissue mRNA, regulated by hypertension, was primarily concentrated in the complement and coagulation cascades and cytokine-cytokine receptor interactions. Compared with SHR, the SGLT2i treatment group was associated with myocardial contraction. Investigation into the lncRNA-mRNA regulatory network and competing endogenous RNA (ceRNA) network suggested that the potential roles of these differentially expressed (DE) lncRNAs and mRNAs were tied to processes such as collagen fibril organization, inflammatory response, and extracellular matrix (ECM) modifications. We found that the expression of Col3a1, C1qa, and lncRNA NONRATT007139.2 were altered in the SHR group and that SGLT2i treatment reversed these changes. Our results suggest that dapagliflozin effectively reverses hypertension-induced myocardial remodeling through a lncRNA-mRNA transcriptional regulatory network, with immune cell-mediated ECM deposition as a potential regulatory target. This underlines the potentiality of SGLT2i and genes related to immunity as promising targets for the treatment of hypertension.

Acute and chronic effects of levosimendan in the ZSF1 obese rat model of heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFpEF) is a syndrome characterized by impaired cardiovascular reserve in which therapeutic options are scarce. Our aim was to evaluate the inodilator levosimendan in the ZSF1 obese rat model of HFpEF. Twenty-week-old male Wistar-Kyoto (WKY), ZSF1 lean (ZSF1 Ln) and ZSF1 obese rats chronically treated for 6-weeks with either levosimendan (1 mg/kg/day, ZSF1 Ob + Levo) or vehicle (ZSF1 Ob + Veh) underwent peak-effort testing, pressure-volume (PV) haemodynamic evaluation and echocardiography (n = 7 each). Samples were collected for histology and western blotting. In obese rats, skinned and intact left ventricular (LV) cardiomyocytes underwent in vitro functional evaluation. Seven additional ZSF1 obese rats underwent PV evaluation to assess acute levosimendan effects (10 µg/kg + 0.1 µg/kg/min). ZSF1 Ob + Veh presented all hallmarks of HFpEF, namely effort intolerance, elevated end-diastolic pressures and reduced diastolic compliance as well as increased LV mass and left atrial area, cardiomyocyte hypertrophy and increased interstitial fibrosis. Levosimendan decreased systemic arterial pressures, raised cardiac index, and enhanced LV relaxation and diastolic compliance in both acute and chronic experiments. ZSF1 Ob + Levo showed pronounced attenuation of hypertrophy and interstitial fibrosis alongside increased effort tolerance (endured workload raised 38 %) and maximum O2 consumption. Skinned cardiomyocytes from ZSF 1 Ob + Levo showed a downward shift in sarcomere length-passive tension relationship and intact cardiomyocytes showed decreased diastolic Ca2+ levels and enhanced Ca2+ sensitivity. On molecular grounds, levosimendan enhanced phosphorylation of phospholamban and mammalian target of rapamycin. The observed effects encourage future clinical trials with levosimendan in a broad population of HFpEF patients.

Short-chain fatty acids ameliorate experimental anti-glomerular basement membrane disease.

BACKGROUND: Short-chain fatty acids (SCFAs), as the link between gut microbiota and the immune system, had been reported to be protective in many autoimmune diseases by the modulation of T cell differentiation. The pathogenic role of autoreactive Th1 and Th17 cells and the protective role of Treg cells in the pathogenesis of anti-GBM disease have been fully demonstrated. Thus, the present study aimed to investigate the therapeutic effects of SCFAs in a rat model of anti-GBM disease. MATERIALS AND METHODS: Experimental anti-GBM disease was constructed by immunizing Wistar Kyoto rats with a nephrogenic T cell epitope α3127-148, and intervened by sodium acetate, sodium propionate, or sodium butyrate, 150 mM in the drinking water from day 0 to 42. Kidney injury was accessed by the biochemical analyzer, immunofluorescence, and immunohistochemistry. Antibody response was detected by ELISA. T cell clustering and proliferation were detected by flow cytometry. Human kidney 2 (HK2) cells were stimulated in vitro and cytokines were assessed by quantitative real-time PCR. RESULTS: Treatment with sodium acetate, sodium propionate, or sodium butyrate ameliorated the severity of kidney impairment in rats with anti-GBM glomerulonephritis. In the sodium butyrate-treated rats, the urinary protein, serum creatinine, and blood urea nitrogen levels were significantly lower; the percentage of crescent formation in glomeruli was significantly reduced; and the kidneys showed reduced IgG deposition, complement activation, T cell, and macrophage infiltration as well as the level of circulating antibodies against anti-α3(IV)NC1. The treatment of sodium butyrate reduced the α3127-148-specific T cell activation and increased the Treg cells differentiation and the intestinal beneficial bacteria flora. It also alleviated the damage of HK2 cells treated with inflammatory factors and complement. CONCLUSION: Treatment with SCFAs, especially butyrate, alleviated anti-GBM nephritis in rat model, indicating its potential therapeutic effects in clinical usage.