SARS-CoV-2 Spike Protein S1 Exposure Increases Susceptibility to Angiotensin II-Induced Hypertension in Rats by Promoting Central Neuroinflammation and Oxidative Stress.

The SARS-CoV-2 spike S1 subunit (S1) can cross the blood-brain barrier and elicit neuroinflammatory response independent of viral infection. Here we examined whether S1 influences blood pressure (BP) and sensitizes the hypertensive response to angiotensin (ANG) II by enhancing neuroinflammation and oxidative stress in hypothalamic paraventricular nucleus (PVN), a key brain cardiovascular regulatory center. Rats received central S1 or vehicle (VEH) injection for 5 days. One week after injection, ANG II or saline (control) was subcutaneously delivered for 2 weeks. S1 injection induced greater increases in BP, PVN neuronal excitation and sympathetic drive in ANG II rats but had no effects in control rats. One week after S1 injection, mRNA for proinflammatory cytokines and oxidative stress marker were higher but mRNA of Nrf2, the master regulator of inducible antioxidant and anti-inflammatory responses, was lower in the PVN in S1-injected rats than in VEH-injected rats. Three weeks after S1 injection, mRNA for proinflammatory cytokines and oxidative stress marker, microglia activation and reactive oxygen species in the PVN were comparable between S1 and VEH treated control rats but were elevated in two groups of ANG II rats. Notably, ANG II-induced elevations in these parameters were exaggerated by S1. Interestingly, ANG II increased PVN Nrf2 mRNA in VEH-treated rats but not in S1-treated rats. These data suggest that S1 exposure has no effect on BP, but post-S1 exposure increases susceptibility to ANG II-induced hypertension by downregulating PVN Nrf2 to promote neuroinflammation and oxidative stress and augment sympathetic excitation.

Sevoflurane and isoflurane inhibit KCl-induced, Rho kinase-mediated, and PI3K-participated vasoconstriction in aged diabetic rat aortas.

BACKGROUND: The mechanism of volatile anesthetics on vascular smooth muscle (VSM) contraction in the setting of diabetes mellitus (DM) remains unclear. The current study was designed to determine the effects of sevoflurane (SEVO) and isoflurane (ISO) on phosphoinositide 3-kinase (PI3K) and Rho kinase (ROCK) mediated KCl-induced vasoconstriction in aged type 2 diabetic rats. METHODS: KCl-induced (60 mM) contractions were examined in endothelium-denuded aortic rings from aged T2DM Otsuka Long-Evans Tokushima Fatty (OLETF) rats (65-70 weeks old), control age-matched nondiabetic Long-Evans Tokushima Otsuka (LETO) rats and young Wistar rats (6-8 weeks old). The effects of SEVO or ISO (1-3 minimum alveolar concentration, MAC) on KCl-induced vasoconstriction, as well as those of LY294002 (PI3K inhibitor) and Y27632 (ROCK inhibitor) were measured in aortic rings from the three groups using an isometric force transducer. RESULTS: KCl induced rapid and continuous contraction of aortic smooth muscle in the three groups, and the contraction was more obvious in OLETF rats. SEVO and ISO inhibited KCl-induced vasoconstriction in a concentration-dependent manner and were suppressed by LY294002 (10 µM) and Y27632 (1 µM). SEVO had a stronger inhibitory effect on the aortas of young Wistar rats than ISO, especially at 2 MAC and 3 MAC (P < 0.05). In aged rats, the inhibitory effect of ISO was stronger than that of SEVO, especially OLETF rats. There was no significant difference in the effects of different concentrations of ISO on arterial contraction among the three groups (P > 0.05). The effects of 1 MAC SEVO on Wistar rats and 3 MAC SEVO on OLETF rats, however, were noticeably and significantly different (P < 0.05). Compared with the control condition, LY294002 and Y27632 had the most noticeable effect on the KCl-induced contraction of aortic rings in OLETF rats (P < 0.01). CONCLUSION: SEVO (3 MAC), ISO (1, 2, 3 MAC), LY294002 and Y27632 have more significant inhibitory effect on the contraction of vascular smooth muscle in aged T2MD rats. The mechanism of SEVO and ISO in vascular tension in T2DM is partly due to changes in PI3K and/or Rho kinase activity.

Peripheral EphrinB1/EphB1 signalling attenuates muscle hyperalgesia in MPS patients and a rat model of taut band-associated persistent muscle pain.

BACKGROUND: Myofascial pain syndrome (MPS) is an important clinical condition that is characterized by chronic muscle pain and a myofascial trigger point (MTrP) located in a taut band (TB). Previous studies showed that EphrinB1 was involved in the regulation of pathological pain via EphB1 signalling, but whether EphrinB1-EphB1 plays a role in MTrP is not clear. METHODS: The present study analysed the levels of p-EphB1/p-EphB2/p-EphB3 in biopsies of MTrPs in the trapezius muscle of 11 MPS patients and seven healthy controls using a protein microarray kit. EphrinB1-Fc was injected intramuscularly to detect EphrinB1s/EphB1s signalling in peripheral sensitization. We applied a blunt strike to the left gastrocnemius muscles (GM) and eccentric exercise for 8 weeks with 4 weeks of recovery to analyse the function of EphrinB1/EphB1 in the muscle pain model. RESULTS: P-EphB1, p-EphB2, and p-EphB3 expression was highly increased in human muscles with MTrPs compared to healthy muscle. EphB1 (r = 0.723, n = 11, P < 0.05), EphB2 (r = 0.610, n = 11, P < 0.05), and EphB3 levels (r = 0.670, n = 11, P < 0.05) in the MPS group were significantly correlated with the numerical rating scale (NRS) in the MTrPs. Intramuscular injection of EphrinB1-Fc produces hyperalgesia, which can be partially prevented by pre-treatment with EphB1-Fc. The p-EphB1 contents in MTrPs of MPS animals were significantly higher than that among control animals (P < 0.01). Intramuscular administration of the EphB1 inhibitor EphB1-Fr significantly suppressed mechanical hyperalgesia. CONCLUSIONS: The present study showed that the increased expression of p-EphB1/p-EphB2/p-EphB3 was related to MTrPs in patients with MPS. This report is the first study to examine the function of EphrinB1-EphB1 signalling in primary muscle afferent neurons in MPS patients and a rat animal model. This pathway may be one of the most important and promising targets for MPS.

Inhibition of Peripheral ERK Signaling Ameliorates Persistent Muscle Pain Around Trigger Points in Rats.

The purpose of this study was to investigate whether the ERK signaling pathway was involved in ameliorating chronic myofascial hyperalgesia from contused gastrocnemius muscle in rats. We established an animal model associated with myofascial pain syndrome and described the mechanism of muscle pain in an animal model. Changes in the mechanical pain threshold were observed 0.5, 1, 2, 3, 4, 5, 8, 12, 18, and 24 h after ERK inhibitor injection around myofascial trigger points (MTrPs) of the gastrocnemius muscle in rats. Morphological changes in gastrocnemius muscle cells were observed by hematoxylin and eosin (H&E) staining. ERK signaling pathway activation was detected through immunohistochemistry and Western blotting. The main morphological characteristics of injured muscle fibers around MTrPs include gathered circular or elliptical shapes of different sizes in the cross-section and continuous inflated and tapering fibers in the longitudinal section. After intramuscular injection of U0126 (ERK inhibitor), the mechanical pain threshold significantly increased. The reduction in mechanical hyperalgesia was accompanied by reduced ERK protein phosphorylation, myosin light chain kinase (MLCK) protein, p-MLC protein expression, and the cross-sectional area of skeletal muscle cells around MTrPs. An ERK inhibitor contributed to the attenuation of mechanical hyperalgesia in the rat myofascial pain model, and the increase in pain threshold may be related to MLCK downregulation and other related contraction-associated proteins by ERK.

The pathophysiological nature of sarcomeres in trigger points in patients with myofascial pain syndrome: A preliminary study.

BACKGROUND: Myofascial pain syndrome (MPS) has a high global prevalence and is associated with myofascial trigger points (MTrPs) in taut bands or nodules. Little is known about the aetiology. The current study assessed the pathophysiological characteristics of MTrPs in MPS patients. METHODS: Biopsies of the trapezius muscle were collected from the MTrPs of MPS patients (MTrP group; n = 29) and from healthy controls (control group; n = 24), and their morphologies were analysed via haematoxylin-eosin (H&E) and Masson staining. A protein microarray was used to detect the receptor tyrosine kinase (RTK) family proteins. mRNA and long non-coding RNA (lncRNA) sequencing and analysis were conducted, and immunohistochemistry and Western blotting were used to examine the expression of EphB and Rho family proteins. RESULTS: Abnormally contracted sarcomeres showed enlarged, round fibres without inflammation or fibrosis. An lncRNA-mRNA network analysis revealed activation of muscle contraction signalling pathways in MTrP regions. Among RTK family proteins, 15 exhibited increased phosphorylation, and two exhibited decreased phosphorylation in the MTrP regions relative to control levels. In particular, EphB1/EphB2 phosphorylation was increased on the muscle cell membranes of abnormal sarcomeres. RhoA and Rac1, but not cell division control protein 42 (Cdc42), were activated in the abnormal sarcomeres. CONCLUSIONS: EphB1/EphB2 and RhoA/Rac1 might play roles in the aetiology of abnormally contracted sarcomeres in MTrPs without inflammatory cell infiltration and fibrotic adhesion. SIGNIFICANCE: Contracted sarcomeres were found in MTrP regions, which is consistent with the MTrP formation hypothesis. EphB1/EphB2 and RhoA/Rac1 might play roles in the sarcomere contractile sites of MTrPs, which may be promising therapeutic targets.

Peripheral FGFR1 Regulates Myofascial Pain in Rats via the PI3K/AKT Pathway.

Myofascial pain syndrome (MPS) is a type of skeletal pain identified by myofascial trigger points (MTrPs). The formation of MTrPs is linked to muscle damage. The fibroblast growth factor receptor (FGFR1) has been found to cause pain sensitivity while repairing tissue damage. The aim of the current study was to explore the mechanism of FGFR1 in MTrPs. We used a RayBio human phosphorylation array kit to measure p-FGFR1 levels in human control subjects and patients with MTrPs. P-FGFR1 was upregulated in the patients with MTrPs. Then a rat model of MPS was established by a blunt strike on the left gastrocnemius muscles (GM) and eccentric-exercise for 8 weeks with 4 weeks of recovery. After establishing the MPS model, the morphology of the GM changed, and the differently augmented sizes of round fibers (contracture knots) in the transverse section and fusiform shapes in the longitudinal section were clearly seen in the rats with myofascial pain. The expression of p-FGFR1 was upregulated on the peripheral nerves and dorsal root ganglion neurons in the MTrPs group. The spinal Fos protein expression was increased in the MTrPs group. Additionally, the mechanical pain threshold was reduced, and the expression of FGF2, p-FGFR1, PI3K-p110γ, and p-AKT increased in the MTrPs group. PD173074 increased the mechanical pain threshold of the MTrPs group, and inhibited the expression of p-FGFR1, PI3K-p110γ, and p-AKT. Moreover, LY294002 increased the mechanical pain threshold of the MTrPs group. These findings suggest that FGFR1 may regulate myofascial pain in rats through the PI3K/AKT pathway.

Endotracheal administration for intraoperative acute massive pulmonary embolism during laparoscopic hepatectomy: A case report.

INTRODUCTION: Acute pulmonary embolism (APE) during an operation is a very urgent occurrence, especially when the patient with hemodynamic instability. Generally, drugs are administered intravenously; however, these drugs have little effects under most circumstances. We present a case of successful resuscitation in a patient with endotracheal administration. PATIENT CONCERNS: A 67-year-old female presented for laparoscopic hepatectomy. Acute pulmonary gas embolism occurred during the operation with hemodynamic instability. The total amount of carbon dioxide and argon reached 300 mL. We used a novel way of administering drugs instead of intravenous administration for rescuing and the patient condition had improved greatly and was discharged from the hospital without any neurological deficits. DIAGNOSES: A diagnosis of APE was made because of a lot of gas was extracted out from central venous catheter and sudden observable decrease in end-tidal CO2. INTERVENTIONS: These measures included endotracheal administration, position adjustment, manual ventilation, and gas extraction. OUTCOMES: The patient was discharged from the hospital and had no signs of neurological deficits. CONCLUSION: Intravenous administration may not the best appropriate way of administration when patients occurred APE. Endotracheal administration as a unique method may work wonders and has the value of research and application.