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-ß-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.

Role of blood-borne factors in sympathoexcitation-mediated hypertension: Potential neurally mediated hypertension in preeclampsia.

Hypertension remains a threat for society due to its unknown causes, preventing proper management, for the growing number of patients, for its state as a high-risk factor for stroke, cardiac and renal complication and as cause of disability. Data from clinical and animal researches have suggested the important role of many soluble factors in the pathophysiology of hypertension through their neuro-stimulating effects. Central targets of these factors are of molecular, cellular and structural nature. Preeclampsia (PE) is characterized by high level of soluble factors with strong pro-hypertensive activity and includes immune factors such as proinflammatory cytokines (PICs). The potential neural effect of those factors in PE is still poorly understood. Shedding light into the potential central effect of the soluble factors in PE may advance our current comprehension of the pathophysiology of hypertension in PE, which will contribute to better management of the disease. In this paper, we summarized existing data in respect of hypothesis of this review, that is, the existence of the neural component in the pathophysiology of the hypertension in PE. Future studies would address this hypothesis to broaden our understanding of the pathophysiology of hypertension in PE.

Acetylcholinesterase inhibition with Pyridostigmine attenuates hypertension and neuroinflammation in the paraventricular nucleus in rat model for Preeclampsia.

Preeclampsia (PE) is characterized by hypertension, autonomic imbalance and inflammation. The subfornical organ (SFO) reportedly relays peripheral inflammatory mediator's signals to the paraventricular nucleus (PVN), a brain autonomic center shown to mediate hypertension in hypertensive rat but not yet in PE rat models. Additionally, we previously showed that Pyridostigmine (PYR), an acetylcholinesterase inhibitor, attenuated placental inflammation and hypertension in PE models. In this study, we investigated the effect of PYR on the activities of these brain regions in PE model. PYR (20 mg/kg/day) was administered to reduced uterine perfusion pressure (RUPP) Sprague-Dawley rat from gestational day (GD) 14 to GD19. On GD19, the mean arterial pressure (MAP) was recorded and samples were collected for analysis. RUPP rats exhibited increased MAP (P = 0.0025), elevated circulating tumor necrosis factor-α (TNF-α, P = 0.0075), reduced baroreflex sensitivity (BRS), increased neuroinflammatory markers including TNF-α, interleukin-1ß (IL-1ß), microglial activation (P = 0.0039), oxidative stress and neuronal excitation within the PVN and the SFO. Changes in MAP, in molecular and cellular expression induced by RUPP intervention were improved by PYR. The ability of PYR to attenuate TNF-α mediated central effect was evaluated in TNF-α-infused pregnant rats. TNF-α infusion-promoted neuroinflammation in the PVN and SFO in dams was abolished by PYR. Collectively, our data suggest that PYR improves PE-like symptoms in rat by dampening placental ischemia and TNF-α-promoted inflammation and pro-hypertensive activity in the PVN. This broadens the therapeutical potential of PYR in PE.

Pyridostigmine ameliorates preeclamptic features in pregnant rats by inhibiting tumour necrosis factor-α synthetsis and antagonizing tumour necrosis factor-α-related effects.

OBJECTIVE: Preeclampsia is a hypertensive disorder of pregnancy marked by an excessive inflammatory response. The anti-inflammatory effect of pyridostigmine (PYR) was previously reported; however, its role in hypertensive pregnancies remains unclear. We hypothesized that PYR could attenuate increased blood pressure and other pathological features in preeclampsia models. METHODS: The expression of tumour necrosis factor (TNF)-α was evaluated in normal and preeclampsia pregnant women. PYR (20 mg/kg) was administered daily to reduced uterine perfusion pressure (RUPP) and TNF-α (150 ng/day) infused rats from gestation day 14 to GD19. In a cell culture experiment, the effect of acetylcholine (ACh) on TNF-α-stimulated primary human umbilical endothelial cells (HUVEC) was assessed. RESULTS: Preeclampsia women had higher placental TNF-α expression than normal pregnant women. Mean arterial pressure (MAP) in the RUPP group was higher than in the Sham group. PYR inhibited serum and placental acetylcholinesterase activity in rats, and reduced MAP, placental oxidative stress, apoptosis and inflammation in the RUPP group but not in the Sham group. In addition, PYR significantly attenuated the TNF-α-induced increase in MAP, placental oxidative stress and apoptosis. Moreover, TNF-α decreased cell viability and increased the number of TUNEL-positive nuclei of HUVEC, which could largely be abolished by ACh treatment. CONCLUSION: Collectively, PYR ameliorated hypertension and other preeclampsia-like symptoms in rat models of preeclampsia not only by inhibiting the synthesis of TNF-α but also by acting against TNF-α-induced detrimental effects directly, which is worthy of further investigation and may be used as a potential agent for preeclampsia management.