Endothelin A (ETA) Receptors Are Involved in Augmented Adrenergic Vasoconstriction and Blunted Nitric Oxide-Mediated Relaxation of Penile Arteries from Insulin-Resistant Obese Zucker Rats

Effect of different high altitudes on vascular endothelial function in healthy people

BACKGROUND

The aim of the study was to provide a theoretical basis for the early diagnosis and prediction of acute altitude sickness, to provide a better entry mode for healthy people from plain areas to plateau areas, and to preliminarily clarify the possible mechanism of this approach.

METHODS

We measured endothelin-1 (ET-1), asymmetric dimethylarginine (ADMA), vascular endothelial growth factor (VEGF), nitric oxide (NO), and hypoxia-inducible factor 1 (HIF-1) levels in each sample and determined flow-mediated dilation (FMD) values using a portable OMRON color Doppler with a 7.0- to 12.0-MHz linear array probe. We used the Lewis Lake score to diagnose acute mountain sickness (AMS) and to stratify the disease severity.

RESULTS

We found no cases of AMS at any of the studied elevation gradients. We found significant differences in FMD values between individuals when at 400 m above sea level and when at 2200, 3200, and 4200 m above sea level (P < .05) but found no significant differences among those at 2200, 3200, and 4200 m. Our variance analysis showed that serum ET-1, VEGF, ADMA, NO, and HIF-1 levels in individuals at ≥3000 m and those at subplateau and plain areas (<3000 m) significantly differed (P < .05). The level of these factors also significantly differed between individuals at elevation gradients of plateau areas (3260 m vs 4270 m) (P < .05). We found no significant differences in serum ET-1, VEGF, and ADMA levels between individuals at the plateau (2260 m) and plain (400 m) areas (P > .05). NO and HIF-1 levels were significantly different in serum samples from individuals between the plateau (2260 m) and plain (400 m) areas (P < .05). However, with increasing altitude, the NO level gradually increased, whereas ET-1, ADMA, VEGF, and HIF-1 levels showed a decreasing trend. With the increase of altitude, there is no correlation between the trend of FMD and hematologic-related factors such as VEGF, NO, and HIF-1.

CONCLUSION

A healthy young male population ascending to a high-altitude area experiences a low incidence of AMS. Entering an acute plateau exposure environment from different altitude gradients may weaken the effect of acute highland exposure on vascular endothelial dysfunction in healthy individuals. Changes in serum ET-1, VEGF, ADMA, NO, and HIF-1 levels in healthy young men may be related to the body's self-regulation and protect healthy individuals from AMS. A short stay in a subplateau region may initiate an oxygen-free preconditioning process in healthy individuals, thereby protecting them from AMS. Noninvasive brachial artery endothelial function test instead of the detection of invasive hematologic-related factors for early diagnosis and prediction of the occurrence and severity of acute high-altitude disease is still lack of sufficient theoretical basis.

Pioglitazone Modulates the Vascular Contractility in Hypertension by Interference with ET-1 Pathway

Endothelin-1 (ET-1) is an important modulator of the vascular tone and a proinflammatory molecule that contributes to the vascular damage observed in hypertension. Peroxisome-proliferator activated receptors-γ (PPARγ) agonists show cardioprotective properties by decreasing inflammatory molecules such as COX-2 and reactive oxygen species (ROS), among others. We investigated the possible modulatory effect of PPARγ activation on the vascular effects of ET-1 in hypertension. In spontaneously hypertensive rats (SHR), but not in normotensive rats, ET-1 enhanced phenylephrine-induced contraction through ET_A by a mechanism dependent on activation of TP receptors by COX-2-derived prostacyclin and reduction in NO bioavailability due to enhanced ROS production. In SHR, the PPARγ agonist pioglitazone (2.5 mg/Kg·day, 28 days) reduced the increased ET_A levels and increased those of ET_B. After pioglitazone treatment of SHR, ET-1 through ET_B decreased ROS levels that resulted in increased NO bioavailability and diminished phenylephrine contraction. In vascular smooth muscle cells from SHR, ET-1 increased ROS production through AP-1 and NFκB activation, leading to enhanced COX-2 expression. These effects were blocked by pioglitazone. In summary, in hypertension, pioglitazone shifts the vascular ET_A/ET_B ratio, reduces ROS/COX-2 activation and increases NO availability; these changes explain the effect of ET-1 decreasing phenylephrine-induced contraction.

The Influence of Bisphenol A (BPA) on Neuregulin 1-Like Immunoreactive Nerve Fibers in the Wall of Porcine Uterus

Bisphenol A (BPA), a substance commonly used in the manufacture of plastics, shows multidirectional negative effects on humans and animals. Due to similarities to estrogens, BPA initially leads to disorders in the reproductive system. On the other hand, it is known that neuregulin 1 (NRG-1) is an active substance which enhances the survivability of cells, inhibits apoptosis, and protects tissues against damaging factors. Because the influence of BPA on the nervous system has also been described, the aim of the present study was to investigate for the first time the influence of various doses of BPA on neuregulin 1-like immunoreactive (NRG-1-LI) nerves located in the porcine uterus using the routine single- and double-immunofluorescence technique. The obtained results have shown that BPA increases the number and affects the neurochemical characterization of NRG-1-LI in the uterus, and changes are visible even under the impact of small doses of this toxin. The character of observed changes depended on the dose of BPA and the part of the uterus studied. These observations suggest that NRG-1 in nerves supplying the uterus may play roles in adaptive and protective mechanisms under the impact of BPA.

The effect of low-intensity extracorporeal shockwave therapy in an obesity-associated erectile dysfunction rat model

OBJECTIVES

To investigate the feasibility of the Zucker fatty (ZF) rat as a model for research in to obesity-associated erectile dysfunction (OAED) and to determine the effect of low-intensity extracorporeal shockwave therapy (Li-ESWT) on penile tissue and function in these rats.

MATERIALS AND METHODS

Eight new-born male Zucker lean (ZL group) rats (ZUC-Lepr^fa 186) and 16 new-born male ZF rats (ZUC-Lepr^fa 185) were injected with 5-ethynyl-2'-deoxyuridine (EdU) at birth to identify and monitor endogenous stem cells. Insulin tolerance testing was performed at 10 weeks of age. Beginning at 12 weeks of age, eight ZF rats were kept as controls, and the remaining eight ZF rats were treated with Li-ESWT (0.02 mJ/mm² , 3 Hz, 500 pulses; ZF + SW group) twice a week for 4 weeks. Following a 1-week washout period, erectile function was evaluated by measuring intracavernosal pressure (ICP) and mean arterial pressure (MAP). Penile tissues were then harvested for histological study to assess smooth muscle/collagen content and endothelium content in the corpora cavernosum. LipidTOX™ staining was used to evaluate lipid accumulation. EdU, as a marker of cell activation, and phosphorylated histone 3 (H3P), as a marker of cell mitosis, were also assessed.

RESULTS

The ICP/MAP indicated that erectile function was severely impaired in the ZF group as compared with the ZL group. In the ZF + SW group, erectile function was significantly improved (P < 0.05). Muscle atrophy was seen in the ZF group, while Li-ESWT increased the muscle content in ZF + SW group. Moreover, the penile endothelium was damaged in the ZF group, and Li-ESWT enhanced the regeneration of endothelial cells (P < 0.01) in the ZF + SW group. Lipid accumulation was seen in the penile tissue of ZF rats. Li-ESWT significantly reduced both the amount and the distribution pattern of LipidTOX, suggesting decreased overall lipid infiltration. Furthermore, Li-ESWT increased EdU-positive cells and markedly enhanced the phosphorylation level of H3P at Ser-10 in the ZF + SW group. Most H3P-positive cells were located within smooth muscle cells, with some located in the endothelium suggesting that these tissues are the reservoirs of penile stem/progenitor cells.

CONCLUSION

ZF rats can serve as an animal model in which to study OAED. This study reveals that obesity impairs erectile function by causing smooth muscle atrophy, endothelial dysfunction, and lipid accumulation in the corpus cavernosum. Li-ESWT restored penile haemodynamic parameters in the ZF rats by restoring smooth muscle and endothelium content and reducing lipid accumulation. The underlying mechanism of Li-ESWT appears to be activation of stem/progenitor cells, which prompts cellular proliferation and accelerates penile tissue regeneration. Our findings are of interest, not just as a validation of this emerging treatment for erectile dysfunction, but also as a novel and potentially significant method to modulate endogenous stem/progenitor cells in other disease processes.

Alterations in endothelin receptors following hemorrhage and resuscitation by centhaquin

Endothelin-1 (ET-1) acts on ET(A) and ET(B) receptors and has been implicated in hemorrhagic shock (shock). We determined effect of shock and resuscitation by hypertonic saline (saline) or centhaquin on ET(A) and ET(B) receptor expression. Rats were anesthetized, a pressure catheter was placed in the left femoral artery; blood was withdrawn from the right femoral artery to bring mean arterial pressure (MAP) to 35 mm Hg for 30 min, resuscitation was performed and 90 min later sacrificed to collect samples for biochemical estimations. Resuscitation with centhaquin decreased blood lactate and increased MAP. Protein levels of ET(A) or ET(B) receptor were unaltered in the brain, heart, lung and liver following shock or resuscitation. In the abdominal aorta, shock produced an increase (140 %) in ET(A) expression which was attenuated by saline and centhaquin; ET(B) expression was unaltered following shock but was increased (79 %) by centhaquin. In renal medulla, ET(A) expression was unaltered following shock, but was decreased (-61 %) by centhaquin; shock produced a decrease (-34 %) in ET(B) expression which was completely attenuated by centhaquin and not saline. Shock induced changes in ET(A) and ET(B) receptors in the aorta and renal medulla are reversed by centhaquin and may be contributing to its efficacy.

In Situ Activation and Preservation of Penile Progenitor Cells Using Icariside II in an Obesity-Associated Erectile Dysfunction Rat Model

Obesity-associated erectile dysfunction (ED) involves pathologic change that may be related to deficit of the penile endogenous stem/progenitor cells. Therefore, an in-depth study of the penile stem/progenitor cells in the pathogenesis of ED is warranted. For this study, eight Zucker Lean (ZUC-Lepr^fa 186; ZL group) and 16 Zucker Fatty (ZUC-Lepr^fa 185; ZF) male rats received an intraperitoneal injection of 5-ethynyl-2-deoxyuridine (EdU) to track endogenous stem cells. Twelve weeks later, the ZF rats were randomized to gavage feeding with 1.5 mg/kg/day of icariside II (ZF + ICA II group) or the solvent (ZF group). Treatment lasted 4 weeks and was followed by a 1-week washout period. ZF rats had impaired erectile function with related pathologic changes compared with ZL rats. ICA II treatment restored erectile function and prevented smooth muscle atrophy, endothelial dysfunction, and lipid accumulation compared with no treatment. EdU label-retaining cell levels were higher in the ZF + ICA II group compared with the ZF group. Histone 3 phosphorylation at Ser 10, a specific mitotic cell marker, was additionally used to identify dividing cells. ICA II activated more penile stem cells to proliferate in ZF rats compared with ZL rats. These results suggest that ZF rats can be used as a model for obesity-associated ED and that ICA II improves erectile function and pathologic changes through endogenous progenitor cell preservation and proliferation.