Astaxanthin Ameliorates Blood Pressure in Salt-Induced Prehypertensive Rats Through ROS/MAPK/NF-κB Pathways in the Hypothalamic Paraventricular Nucleus

Activation AMPK in Hypothalamic Paraventricular Nucleus Improves Renovascular Hypertension Through ERK1/2-NF-κB Pathway

Hypertension is a globally prevalent disease, but the pathogenesis remains largely unclear. AMP-activated protein kinase (AMPK) is a nutrition-sensitive signal of cellular energy metabolism, which has a certain influence on the development of hypertension. Previously, we found a down-regulation of the phosphorylated (p-) form of AMPK, and the up-regulation of the angiotensin II type 1 receptor (AT1-R) and that of p-ERK1/2 in the hypothalamic paraventricular nucleus (PVN) of hypertensive rats. However, the exact mechanism underlying the relationship between AMPK and AT1-R in the PVN during hypertension remains unclear. Thus, we hypothesized that AMPK modulates AT1-R through the ERK1/2-NF-κB pathway in the PVN, thereby inhibiting sympathetic nerve activity and improving hypertension. To examine this hypothesis, we employed a renovascular hypertensive animal model developed via two-kidney, one-clip (2K1C) and sham-operated (SHAM). Artificial cerebrospinal fluid (aCSF), used as vehicle, or 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR, an AMPK activator, 60 μg/day) was microinjected bilaterally in the PVN of these rats for 4 weeks. In 2K1C rats, there an increase in systolic blood pressure (SBP) and circulating norepinephrine (NE). Also, the hypertensive rats had lowered expression of p-AMPK and p-AMPK/AMPK, elevated expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R, increased NF-κB p65 activity in the PVN compared with the levels of these biomarkers in SHAM rats. Four weeks of bilateral PVN injection of AMPK activator AICAR, attenuated the NE level and SBP, increased the expression of p-AMPK and p-AMPK/AMPK, lessened the NF-κB p65 activity, decreased the expression of p-ERK1/2, p-ERK1/2/ERK1/2 and AT1-R in the PVN of 2K1C rats. Data from this study imply that the activation of AMPK within the PVN suppressed AT1-R expression through inhibiting the ERK1/2-NF-κB pathway, decreased the activity of the sympathetic nervous system, improved hypertension.

Oxidative stress-mediated protein sulfenylation in human diseases: Past, present, and future

Reactive Oxygen Species (ROS) refer to a variety of derivatives of molecular oxygen that play crucial roles in regulating a wide range of physiological and pathological processes. Excessive ROS levels can cause oxidative stress, leading to cellular damage and even cell demise. However, moderately elevated levels of ROS can mediate the oxidative post-translational modifications (oxPTMs) of redox-sensitive proteins, thereby affecting protein functions and regulating various cellular signaling pathways. Among the oxPTMs, ROS-induced reversible protein sulfenylation represents the initial form of cysteine oxidation for sensing redox signaling. In this review, we will summarize the discovery, chemical formation, and detection approaches of protein sulfenylation. In addition, we will highlight recent findings for the roles of protein sulfenylation in various diseases, including thrombotic disorders, diabetes, cardiovascular diseases, neurodegenerative diseases, and cancer.

Astaxanthin Alleviates the Process of Cardiac Hypertrophy by Targeting the METTL3/Circ_0078450/MiR-338-3p/GATA4 Pathway

Astaxanthin (ASX) is a natural antioxidant with preventive and therapeutic effects on various human diseases. However, the role of ASX in cardiac hypertrophy and its underlying molecular mechanisms remain unclear.Cardiomyocytes (AC16) were used with angiotensin-II (Ang-II) to mimic the cardiac hypertrophy cell model. The protein levels of hypertrophy genes, GATA4, and methyltransferase-like 3 (METTL3) were determined by western blot analysis. Cell size was assessed using immunofluorescence staining. The expression of circ_0078450, miR-338-3p, and GATA4 were analyzed by quantitative real-time PCR. Also, the interaction between miR-338-3p and circ_0078450 or GATA4 was confirmed by dual-luciferase reporter and RIP assays, and the regulation of METTL3 on circ_0078450 was verified by MeRIP and RIP assays.ASX reduced the hypertrophy gene protein expression and cell size in Ang-II-induced AC16 cells. Circ_0078450 was promoted under Ang-II treatment, and ASX reduced circ_0078450 expression in Ang-II-induced AC16 cells. Circ_0078450 could sponge miR-338-3p to positively regulate GATA4 expression, and GATA4 overexpression overturned the suppressive effect of circ_0078450 knockdown on Ang-II-induced cardiomyocyte hypertrophy. Also, the inhibitory effect of ASX on Ang-II-induced cardiomyocyte hypertrophy could be reversed by circ_0078450 or GATA4 overexpression. In addition, METTL3 mediated the m6A methylation of circ_0078450 to enhance circ_0078450 expression. Moreover, METTL3 knockdown suppressed Ang-II-induced cardiomyocyte hypertrophy by inhibiting circ_0078450 expression.Our data showed that ASX repressed cardiac hypertrophy by regulating the METTL3/circ_0078450/miR-338-3p/GATA4 axis.

Micro-algal astaxanthin improves lambda-cyhalothrin-induced necroptosis and inflammatory responses via the ROS-mediated NF-κB signaling in lymphocytes of carp (Cyprinus carpio L.)

Lambda-cyhalothrin (LCY) is a widely used toxic pesticide that causes harmful effects on the immune organs of fish and aquatic species. Micro-algal astaxanthin (MAA), a heme pigment found in haematococcus pluvialis, has been shown to benefit antioxidants and immunity in aquaculture. To investigate how MAA protects carp lymphocytes from LCY-induced immunotoxicity, a model of fish lymphocytes treated with LCY and/or MAA was established. Lymphocytes from carp (Cyprinus carpio L.) were given LCY (80 μM) and/or MAA (50 μM) as a treatment for a period of 24 h. Firstly, LCY exposure resulted in excessive ROS and malondialdehyde production and reduces antioxidant enzymes (SOD and CAT), indicating a reduced capacity of the antioxidant system. Secondly, the results of flow cytometry and AO/EB labeling proved that lymphocytes treated with LCY have a larger ratio of necroptosis. In addition, LCY upregulated the levels of necroptosis-related regulatory factors (RIP1, RIP3 and MLKL) via the ROS-mediated NF-κB signaling pathway in lymphocytes. Thirdly, LCY treatment caused increased secretion of inflammatory genes (IL-6, INF-γ, IL-4, IL-1β and TNF-α), leading to immune dysfunction in lymphocytes. Surprisingly, LCY-induced immunotoxicity was inhibited by MAA treatment, indicating that it effectively attenuated the LCY-induced changes described above. Overall, we concluded that MAA treatment could ameliorate LCY-induced necroptosis and immune dysfunction by inhibiting the ROS-mediated NF-κB signaling in lymphocytes. It provides insights into the protection of farmed fish from agrobiological threats in fish under LCY and the value of MAA applications in aquaculture.

Resveratrol in the Hypothalamic Paraventricular Nucleus Attenuates Hypertension by Regulation of ROS and Neurotransmitters

BACKGROUND

The hypothalamic paraventricular nucleus (PVN) is an important nucleus in the brain that plays a key role in regulating sympathetic nerve activity (SNA) and blood pressure. Silent mating-type information regulation 2 homolog-1 (sirtuin1, SIRT1) not only protects cardiovascular function but also reduces inflammation and oxidative stress in the periphery. However, its role in the central regulation of hypertension remains unknown. It is hypothesized that SIRT1 activation by resveratrol may reduce SNA and lower blood pressure through the regulation of intracellular reactive oxygen species (ROS) and neurotransmitters in the PVN.

METHODS

The two-kidney one-clip (2K1C) method was used to induce renovascular hypertension in male Sprague-Dawley rats. Then, bilaterally injections of vehicle (artificial cerebrospinal fluid, aCSF, 0.4 μL) or resveratrol (a SIRT1 agonist, 160 μmol/L, 0.4 μL) into rat PVN were performed for four weeks.

RESULTS

PVN SIRT1 expression was lower in the hypertension group than the sham surgery (SHAM) group. Activated SIRT1 within the PVN lowered systolic blood pressure and plasma norepinephrine (NE) levels. It was found that PVN of 2K1C animals injected with resveratrol exhibited increased expression of SIRT1, copper-zinc superoxide dismutase (SOD1), and glutamic acid decarboxylase (GAD67), as well as decreased activity of nuclear factor-kappa B (NF-κB) p65 and NAD(P)H oxidase (NOX), particularly NOX4. Treatment with resveratrol also decreased expression of ROS and tyrosine hydroxylase (TH).

CONCLUSION

Resveratrol within the PVN attenuates hypertension via the SIRT1/NF-κB pathway to decrease ROS and restore the balance of excitatory and inhibitory neurotransmitters.

Exercise Training Attenuates Hypertension via Suppressing ROS/MAPK/NF-κB/AT-1R Pathway in the Hypothalamic Paraventricular Nucleus

Background: Aerobic exercise training (ExT) is beneficial for hypertension, however, its central mechanisms in improving hypertension remain unclear. Since the importance of the up-regulation of angiotensin II type 1 receptor (AT-1R) in the paraventricular nucleus (PVN) of the hypothalamic in sympathoexcitation and hypertension has been shown, we testified the hypothesis that aerobic ExT decreases blood pressure in hypertensive rats by down-regulating the AT-1R through reactive oxygen species (ROS)/mitogen-activated protein kinase (MAPK)/nuclear factors κB (NF-κB) pathway within the PVN. Methods: Forty-eight male Sprague-Dawley (SD) rats were assigned to the following groups: sham operation (SHAM) + kept sedentary (Sed), SHAM + exercise training (ExT), two kidney-one clamp (2K1C) + Sed, and 2K1C + ExT groups. Results: The 2K1C + Sed hypertensive rats showed higher systolic blood pressure (SBP), upregulated ROS, phosphorylated (p-) p44/42 MAPK, p-p38 MAPK, NF-κB p65 activity, and AT-1R expression in the PVN, and increased circulating norepinephrine (NE) than those of SHAM rats. After eight weeks of aerobic ExT, the 2K1C + ExT hypertensive rats showed attenuated NE and SBP levels, suppressed NF-κB p65 activity, and reduced expression of ROS, p-p44/42 MAPK, p-p38 MAPK, and AT-1R in the PVN, relatively to the 2K1C + Sed group. Conclusions: These data are suggestive of beneficial effects of aerobic ExT in decreasing SBP in hypertensive rats, via down-regulating the ROS/MAPK/NF-κB pathway that targets AT-1R in the PVN, and eventually ameliorating 2K1C-induced hypertension.