Search Results (41)

Background/Objectives: Upper airway patency is a key pathophysiological factor in obstructive sleep apnea (OSA). Research has primarily focused on the role of the genioglossus muscle in maintaining airway patency in OSA. However, hypoglossal nerve stimulation (HNS) therapy, which activates the genioglossus muscle, has been associated with poor outcomes in patients with lateral oropharyngeal collapse. The stylopharyngeus muscle is an upper airway dilator muscle that supports the lateral pharyngeal wall. Its role in maintaining upper airway patency and its effect on normal respiratory airflow is unclear. We hypothesize that bilateral transection of the stylopharyngeus muscles disrupts normal breathing. Currently, no animal model depicting lateral pharyngeal collapse has been reported. This study aims to introduce a novel rodent model with bilateral transection of the stylopharyngeus muscles to examine its effect on respiratory airflow and tracing. Methods: Adult male Sprague Dawley rats were divided into two groups: (1) bilateral stylopharyngeus muscle transection (n = 4) and (2) sham surgery (n = 2). Under anesthesia, the stylopharyngeus muscle was transected bilaterally in the transection group, while only exposure of the muscle was performed in the sham group. Respiratory airflow was measured using whole-body plethysmography before and after surgery, and airflow tracings were analyzed. Results: Significant alterations in respiratory airflow and tracings, particularly a flattening in inspiratory flow and sharp expiratory peaks, were observed on the first post-operative day in the transection group. The flattening of the inspiratory flow persisted over 3 days. No significant changes were noted in the sham group. Conclusions: Bilateral stylopharyngeus muscle transection alters normal airflow in a conscious rodent model, supporting the hypothesis that stylopharyngeus muscle plays a vital role in shaping respiratory airflow. The flattening of the inspiratory airflow is an indication of flow limitations through the upper airway patency due to the loss of stylopharyngeus function. Full article

Selecting suitable crop species is crucial for optimizing the productivity and nutritional content of microgreens. In this study, twenty-three diverse microgreen species, grown under controlled conditions, were analyzed for yield, bioactive compounds, and antioxidant activities. The microgreens were cultivated on a peat substrate in a controlled environment, with a growth period of 6 to 20 days from planting to harvest. Conditions were maintained at 25 ± 2 °C, a 16 h photoperiod, CO₂ concentration of 1000 ppm, relative humidity of 60 ± 2%, and the LED light was set at 330 μmol/m²/s PPFD. Results from the analysis revealed that the yield, bioactive compounds, and antioxidant potential differed significantly among the twenty-three microgreen species. Unfortunately, the superior microgreens exhibiting greater values for all studied traits could not be identified. However, the principal component analysis (PCA) clustered red radish, rat-tailed radish, and Chinese kale microgreens, which were high in both yield and bioactive compounds. In contrast, red holy basil and lemon basil microgreens had high levels of these compounds but low yields. Additionally, a high level of anti-tyrosinase activity was observed in garland chrysanthemum, Chinese mustard, and Chinese cabbage microgreens. Therefore, these microgreen species can be utilized individually or in varying ratios to produce bioactive compounds in different concentrations that are suitable for various applications. The information presented in this study provides valuable insights for health-conscious consumers and growers for selecting superior species with functional implications. Full article

Spinal cord injury (SCI) is a complex clinical condition with a wide range of permanent functional and neurological consequences. A prime factor limiting the patient’s quality of life (QoL) is difficulties in bladder function. Chronic animal models that help to develop novel therapeutic strategies are highly demanded, but their availability is scarce and frequently accompanied by substantial limitations. We want to provide our detailed protocols that allow full reproducibility of a novel model for investigating both the acute and chronic condition, and give transparency regarding challenges. The preclinical animal model of female rats with mid-thoracic SCI contusion and a permanently implanted urinary catheter allowed the measuring of bladder function repetitively. Over a period of six months, data were collected weekly from the same, conscious individuals. To our knowledge, this is the first study that obtained a clinically relevant urodynamic dataset seamlessly from the acute to the chronic phase in rats with SCI. The ability to generate a complete data set from one single individual, rather than requiring multiple subjects, has the potential to markedly reduce the number of experimental animals, eliminate group differences, and give more flexibility for therapeutic intervention. Future projects could also benefit from the described optimizations in animal care. Full article

Background/Objectives: Sepsis has been shown to depress arterial baroreceptor function, and this effect is counterbalanced by the cholinergic anti-inflammatory pathway. Considering the importance of central adenosine receptors in baroreceptor function, this study tested whether central adenosine A3 receptors (A3ARs) modulate the cholinergic-baroreflex interaction in sepsis and whether this interaction is modulated by mitogen-activated protein kinases (MAPKs) and related proinflammatory cytokines. Methods: Sepsis was induced by cecal ligation and puncture (CLP) and rats were instrumented with femoral and intracisternal (i.c.) catheters. Baroreflex sensitivity (BRS) was measured 24 h later in conscious animals using the vasoactive method, which correlates changes in blood pressure caused by i.v. phenylephrine (PE) and sodium nitroprusside (SNP) to concomitant reciprocal changes in heart rate. Results: The reduction in reflex bradycardic (BRS-PE), but not tachycardic (BRS-SNP), responses elicited by CLP was reversed by i.v. nicotine in a dose-related manner. The BRS-PE effect of nicotine was blunted following intracisternal administration of IB-MECA (A3AR agonist, 4 µg/rat). The depressant action of IB-MECA on the BRS facilitatory action of nicotine was abrogated following central inhibition of MAPK-JNK (SP 600125), PI3K (wortmannin), and TNFα (infliximab), but not MAPK-ERK (PD 98059). Additionally, the nicotine suppression of sepsis-induced upregulation of NFκB and NOX2 expression in the nucleus tractus solitarius (NTS) was negated by A3AR activation. The molecular effect of IB-MECA on NFκB expression disappeared in the presence of SP 600125, wortmannin, or infliximab. Conclusions: The central PI3K/MAPK-JNK/TNFα pathway contributes to the restraining action of A3ARs on cholinergic amelioration of sepsis-induced central neuroinflammatory responses and impairment of the baroreceptor-mediated negative chronotropism. Full article

Extremity trauma, including ischemia (e.g., prolonged tourniquet application or crush), is common among battlefield injuries. Injured muscle releases toxins leading to rhabdomyolysis and, potentially, acute kidney injury (AKI). The goal of this study was to characterize sequelae of ischemic extremity injury over 72 h, focusing on time courses of rhabdomyolysis and AKI. Male Sprague Dawley rats were placed into two groups. Ischemic injury was produced in anesthetized rats using bilateral tourniquets (TK; n = 10) for 5 h; control (CON; n = 9) rats were treated identically without TK application. Indicators of rhabdomyolysis and renal function were measured in conscious rats 1 day preinjury (baseline, BL) and then at 1.5, 24, 48, and 72 h post-TK release. Prolonged TK application produced necrosis in both muscle and bone marrow but not in kidney. The wet/dry weights indicated edema in injured limbs at 72 h (4.1 (0.5) (TK) vs. 2.9 (0.1) (CON); p < 0.001). TK rats exhibited a 100-fold increase in creatine kinase activity compared to CON at 1.5 h (20,040 (7265) U/L vs. 195 (86) U/L (mean (SD); p < 0.0001). TK decreased the mean glomerular filtration rate (GFR; p < 0.001) at 1.5 h, but these values recovered by 24 h in concert with elevated urinary flow and alkalinization. Prolonged ischemic extremity injury therefore produced severe rhabdomyolysis without irreversible renal damage. Full article

Compensatory changes in brain connectivity keep motor symptoms mild in prodromal Parkinson’s disease. Studying compensation in patients is hampered by the steady progression of the disease and a lack of individual baseline controls. Furthermore, combining fMRI with walking is intricate. We therefore used a seed-based metabolic connectivity analysis based on 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) uptake in a unilateral 6-OHDA rat model. At baseline and in the chronic phase 6–7 months after lesion, rats received an intraperitoneal injection of [¹⁸F]FDG and spent 50 min walking on a horizontal treadmill, followed by a brain PET-scan under anesthesia. High activity was found in the cerebellar anterior vermis in both conditions. At baseline, the anterior vermis showed hardly any stable connections to the rest of the brain. The (future) ipsilesional cerebellar hemisphere was not particularly active during walking but was extensively connected to many brain areas. After unilateral dopamine depletion, rats still walked normally without obvious impairments. The ipsilesional cerebellar hemisphere increased its activity, but narrowed its connections down to the vestibulocerebellum, probably aiding lateral stability. The anterior vermis established a network involving the motor cortex, hippocampus and thalamus. Adding those regions to the vermis network of (previously) automatic control of locomotion suggests that after unilateral dopamine depletion considerable conscious and cognitive effort has to be provided to achieve stable walking. Full article

This study explored the therapeutic efficacy of Helianthemum lippii and silver nanoparticles (Ag NPs) synthesized using a H. lippii extract to alleviate cadmium-induced nephrotoxicity in Wistar rats. Sub-acute toxicity assessments of H. lippii (100 mg/kg, 1000 mg/kg, and 4000 mg/kg) and Ag NPs (2 mg/kg and 10 mg/kg) did not find any significant difference, compared with untreated control rats (n = 3 animals/group). Then, the adult Wistar rats were divided into one control (untreated/unexposed) and six experimental groups (n = 5/group): Ag NPs alone, H. lippii alone, exposure to 50 mg/kg CdCl₂ in drinking water for 35 days, exposure to CdCl₂ for 35 days followed by treatment with 0.1 mg/kg/day Ag NPs (intraperitoneal injection) and/or 100 mg/kg/day H. lippii by gavage for 15 days. In the CdCl₂-exposed group, body weight decreased; urea, creatinine, and uric acid concentrations increased (p < 0.05 vs. control), indicative of nephrotoxicity, antioxidant defenses (SOD, GSH, and CAT) were reduced, and malondialdehyde concentration increased. Moreover, the kidney’s architecture in CdCl₂-exposed rats was altered: fibrosis, inflammatory cell infiltration, glomerular destruction, and tubular dilatation. Treatment with H. lippii and/or Ag NPs after CdCl₂ exposure improved some of the renal function and architecture alterations induced by CdCl₂, and also increased body weight. This study underscores the potential therapeutic applications of H. lippii and Ag NPs to decrease oxidative stress and promote xenobiotic detoxification, in line with the growing emphasis on environmentally conscious practices in scientific research and healthcare. Full article

Liver-expressed antimicrobial peptide-2 (LEAP-2) has mutual antagonism with ghrelin, which evokes food intake under a freely fed state. Nevertheless, the impact of LEAP-2 on ghrelin under time-restricted feeding (TRF), which has benefits in the context of metabolic disease, is still unknown. This study aims to explore the impact of central administration of LEAP-2 on the ingestion behavior of rats, which was evaluated using their cumulative food intake in the TRF state. Before intracerebroventricular (ICV) administration of O-n-octanoylated ghrelin (0.1 nmol/rat), as a food-stimulatory model, the rats received various doses of LEAP-2 (0.3, 1, 3 nmol/rat, ICV). Cumulative food intake was recorded at 1, 2, 4, 8, 12, and 24 h after ICV injection under 12 h freely fed and TRF states in a light phase. In 12 h freely fed and TRF states, central administration of ghrelin alone induced feeding behavior. Pre-treatment with LEAP-2 (1 and 3 nmol/rat, ICV) suppressed ghrelin-induced food intake in a dose-dependent manner in a 12 h freely fed state instead of a TRF state, which may have disturbed the balance of ghrelin and LEAP-2. This study provides neuroendocrine-based evidence that may explain why TRF sometimes fails in fighting obesity/metabolic dysfunction-associated steatotic liver disease in clinics. Full article

The present study examined the hypothesis that changes in the oxidation–reduction state of thiol residues in functional proteins play a major role in the expression of the ventilatory responses in conscious rats that occur during a hypoxic–hypercapnic (HH) gas challenge and upon return to room air. A HH gas challenge in vehicle-treated rats elicited robust and sustained increases in minute volume (via increases in frequency of breathing and tidal volume), peak inspiratory and expiratory flows, and inspiratory and expiratory drives while minimally affecting the non-eupneic breathing index (NEBI). The HH-induced increases in these parameters, except for frequency of breathing, were substantially diminished in rats pre-treated with the potent and lipophilic disulfide-reducing agent, L,D-dithiothreitol (100 µmol/kg, IV). The ventilatory responses that occurred upon return to room air were also substantially different in dithiothreitol-treated rats. In contrast, pre-treatment with a substantially higher dose (500 µmol/kg, IV) of the lipophilic congener of the monosulfide, N-acetyl-L-cysteine methyl ester (L-NACme), only minimally affected the expression of the above-mentioned ventilatory responses that occurred during the HH gas challenge or upon return to room air. The effectiveness of dithiothreitol suggests that the oxidation of thiol residues occurs during exposure to a HH gas challenge and that this process plays an essential role in allowing for the expression of the post-HH excitatory phase in breathing. However, this interpretation is contradicted by the lack of effects of L-NACme. This apparent conundrum may be explained by the disulfide structure affording unique functional properties to dithiothreitol in comparison to monosulfides. More specifically, the disulfide structure may give dithiothreitol the ability to alter the conformational state of functional proteins while transferring electrons. It is also possible that dithiothreitol is simply a more efficient reducing agent following systemic injection, although one interpretation of the data is that the effects of dithiothreitol are not due to its reducing ability. Full article

The administration of the α₂-adrenergic receptor agonist clonidine via intracerebroventricular route produces hypotension in pentobarbital-anesthetized rats and pressor responses in conscious normotensive rats. We explored the impact of different anesthetics on the central nervous system-dependent cardiovascular effects of clonidine. Normotensive male Wistar rats with guide cannulas previously implanted in the cerebroventricular system were anesthetized with pentobarbital or ketamine/xylazine and prepared for blood pressure measurement. The animals received intracerebroventricular injections of 10 μg clonidine or 0.6 μg dexmedetomidine, and the effects on the systolic, diastolic, mean arterial pressure, and heart rate were evaluated. The influence of 5 μg yohimbine, a selective α₂-adrenergic receptor antagonist, was also assessed. The i.c.v. microinjection of clonidine decreased all three components of systemic arterial pressure and the heart rate of pentobarbital-anesthetized rats. On the other hand, clonidine increased the blood pressure and generated a less intense reduction in the heart rate of ketamine/xylazine-anesthetized rats. The pressor and bradycardic effects of clonidine in ketamine/xylazine-anesthetized animals were reproduced by dexmedetomidine, a more selective α₂-adrenergic receptor agonist. Notably, the previous intracerebroventricular injection of yohimbine significantly inhibited the hypertensive effect of clonidine and dexmedetomidine. This study discloses that while normotensive rats anesthetized with pentobarbital show hypotensive responses, the stimulation of α₂-adrenergic receptors increases the blood pressure in rats under ketamine/xylazine-induced anesthesia, reproducing the effects seen in conscious normotensive animals. Recognizing the mechanisms involved in these differences may allow us to understand better the final effects of clonidine and other α₂-adrenergic receptor agonists in the central nervous system, contributing to the repurposing of these drugs. Full article

The ubiquitous peptide endothelin is currently under investigation as a modulatory factor of autonomic responses to acute emotional stress. Baseline plasma levels of endothelin alter blood pressure responses, but it remains unclear whether autonomic activity and arrhythmogenesis (i.e., brady- or tachyarrhythmias) are affected. We recorded sympathetic and vagal indices (derived from heart rate variability analysis), rhythm disturbances, voluntary motion, and systolic blood pressure after acute emotional stress in conscious rats with implanted telemetry devices. Two strains were compared, namely wild-type and ET_B-deficient rats, the latter displaying elevated plasma endothelin. No differences in heart rate or blood pressure were evident, but sympathetic responses were blunted in ET_B-deficient rats, contrasting prompt activation in wild-type rats. Vagal withdrawal was observed in both strains at the onset of stress, but vagal activity was subsequently restored in ET_B-deficient rats, accompanied by low voluntary motion during recovery. Reflecting such distinct autonomic patterns, frequent premature ventricular contractions were recorded in wild-type rats, as opposed to sinus pauses in ET_B-deficient rats. Thus, chronically elevated plasma endothelin levels blunt autonomic responses to acute emotional stress, resulting in vagal dominance and bradyarrhythmias. Our study provides further insights into the pathophysiology of stress-induced tachyarrhythmias and syncope. Full article

The enhancement of the endocannabinoid tone might have a beneficial influence on hypertension. Polypharmacology proposes multi-target-directed ligands (MTDLs) as potential therapeutic agents for the treatment of complex diseases. In the present paper, we studied JZL195, a dual inhibitor of the two major endocannabinoid-degrading enzymes, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Hemodynamic parameters were assessed in conscious animals via radiotelemetry and tail-cuff methods and then evaluated by the area under the curve (AUC). Single administration of JZL195 induced dose-dependent weak hypotensive and bradycardic responses in SHR but not in WKY. Similarly, its chronic application revealed only a slight hypotensive potential which, however, effectively prevented the progression of hypertension and did not undergo tolerance. In addition, multiple JZL195 administrations slightly decreased heart rate only in WKY and prevented the gradual weight gain in both groups. JZL195 did not affect organ weights, blood glucose level, rectal temperature and plasma oxidative stress markers. In conclusion, chronic dual FAAH/MAGL inhibition prevents the progression of hypertension in SHR without affecting some basal functions of the body. In addition, our study clearly proves the suitability of AUC for the evaluation of weak blood pressure changes. Full article

Apelin, by stimulation of APJ receptors, induces transient blood pressure (BP) reduction and positive inotropic effects. APJ receptors share high homology with the Ang II type 1 receptor; thus, apelin was proposed to play a protective role in cardiovascular disease by antagonizing the actions of Ang II. In this regard, apelin and apelin-mimetics are currently being studied in clinical trials. However, the chronic effect of apelin in cardiovascular regulation has not been fully investigated. In the current study, blood pressure (BP) and heart rate (HR) were recorded using a telemetry implantation approach in conscious rats, before and during chronic subcutaneous infusion of apelin-13, using osmotic minipumps. At the end of the recording, the cardiac myocyte morphology was examined using H&E staining, and cardiac fibrosis was evaluated by Sirius Red in each group of rats. The results demonstrated that the chronic infusion of apelin-13 did not change either BP or HR. However, under the same condition, the chronic infusion of Ang II induced significant BP elevation, cardiac hypertrophy, and fibrosis. Co-administration of apelin-13 did not significantly alter the Ang II-induced elevation in BP, changes in cardiac morphology, and fibrosis. Taken together, our experiments showed an unexpected result indicating that the chronic administration of apelin-13 did not alter basal BP, nor did it change Ang II-induced hypertension and cardiac hypertrophy. The findings suggest that an APJ receptor biased agonist could be a better therapeutic alternative for treatment of hypertension. Full article

Cardiovascular ailments are a major cause of mortality where over 1.3 billion people suffer from hypertension leading to heart-disease related deaths. Snake venoms possess a broad repertoire of natriuretic peptides with therapeutic potential for treating hypertension, congestive heart failure, and related cardiovascular disease. We now describe several taipan (Oxyuranus microlepidotus) natriuretic peptides TNPa-e which stimulated cGMP production through the natriuretic peptide receptor A (NPR-A) with higher potencies for the rat NPR-A (rNPR-A) over human NPR-A (hNPR-A). TNPc and TNPd were the most potent, demonstrating 100- and 560-fold selectivity for rNPR-A over hNPR-A. In vivo studies found that TNPc decreased diastolic and systolic blood pressure (BP) and increased heart rate (HR) in conscious normotensive rabbits, to a level that was similar to that of human atrial natriuretic peptide (hANP). TNPc also enhanced the bradycardia due to cardiac afferent stimulation (Bezold–Jarisch reflex). This indicated that TNPc possesses the ability to lower blood pressure and facilitate cardiac vagal afferent reflexes but unlike hANP does not produce tachycardia. The 3-dimensional structure of TNPc was well defined within the pharmacophoric disulfide ring, displaying two turn-like regions (RMSD = 1.15 Å). Further, its much greater biological stability together with its selectivity and potency will enhance its usefulness as a biological tool. Full article

Multi-target drug candidate BGP-15 has shown cardioprotective and antiarrhythmic actions in diseased models. Here, we investigated the effects of BGP-15 on ECG and echocardiographic parameters, heart rate variability (HRV), and arrhythmia incidence in telemetry-implanted rats, under beta-adrenergic stimulation by isoproterenol (ISO). In total, 40 rats were implanted with radiotelemetry transmitters. First, dose escalation studies (40–160 mg/kg BGP-15), ECG parameters, and 24 h HRV parameters were assessed. After, rats were divided into Control, Control+BGP-15, ISO, and ISO+BGP-15 subgroups for 2 weeks. ECG recordings were obtained from conscious rats, arrhythmias and HRV parameters were assessed, and echocardiography was carried out. ISO-BGP-15 interaction was also evaluated on an isolated canine cardiomyocyte model. BGP-15 had no observable effects on the ECG waveforms; however, it decreased heart rate. HRV monitoring showed that BGP-15 increased RMSSD, SD1, and HF% parameters. BGP-15 failed to counteract 1 mg/kg ISO-induced tachycardia, but diminished the ECG of ischemia and suppressed ventricular arrhythmia incidence. Under echocardiography, after low-dose ISO injection, BGP-15 administration lowered HR and atrial velocities, and increased end-diastolic volume and ventricle relaxation, but did not counteract the positive inotropic effects of ISO. Two weeks of BGP-15 treatment also improved diastolic function in ISO-treated rats. In isolated cardiomyocytes, BGP-15 prevented 100 nM ISO-induced aftercontractions. Here, we show that BGP-15 increases vagally mediated HRV, reduces arrhythmogenesis, enhances left ventricle relaxation, and suppresses the aftercontractions of cardiomyocytes. As the drug is well tolerated, it may have a clinical value in preventing fatal arrhythmias. Full article