Adaptation of the Cerebrocortical Circulation to Carotid Artery Occlusion Involves Blood Flow Redistribution between Cortical Regions and is Independent of eNOS

Cerebral circulation is secured by feed-forward and feed-back control pathways to maintain and eventually reestablish the optimal oxygen and nutrient supply of neurons in case of disturbances of the cardiovascular system. Using the high temporal and spatial resolution of laser-speckle imaging we aimed to analyze the pattern of cerebrocortical blood flow (CoBF) changes after unilateral (left) carotid artery occlusion (CAO) in anesthetized mice in order to evaluate the contribution of macrovascular (Willis circle) vs. pial collateral vessels as well as that of endothelial nitric oxide synthase (eNOS) to the cerebrovascular adaptation to CAO. In wild-type mice CoBF reduction in the left temporal cortex started immediately after CAO, reaching its maximum (-26%) at 5-10 s. Thereafter, CoBF recovered close to the pre-occlusion level within 30 s indicating the activation of feed-back pathway(s). Interestingly, the frontoparietal cerebrocortical regions also showed CoBF reduction in the left (-17-19%) but not in the right hemisphere, although these brain areas receive their blood supply from the common azygos anterior cerebral artery in mice. In eNOS-deficient animals the acute CoBF reduction after CAO was unaltered, and the recovery was even accelerated as compared to controls. These results indicate that (i) the Willis circle alone is not sufficient to provide an immediate compensation for the loss of one carotid artery, (ii) pial collaterals attenuate the ischemia of the temporal cortex ipsilateral to CAO at the expense of the blood supply of the frontoparietal region, and (iii) eNOS, surprisingly, does not play an important role in this CoBF redistribution

Effects of vitamin D3 derivate calcitriol on pharmacological reactivity of aortic rings in a rodent PCOS model

BACKGROUND: The aim of this study was to examine the effects of the hyperandrogenic state in dihydrotestosterone (DHT)-induced polycystic ovary syndrome (PCOS), the vascular responses to different vasoactive agents, and the modulatory role of vitamin D3. METHODS: APCOS model was induced by DHT application in 20 female Wistar rats. Ten of the DHT treated rats simultaneously received calcitriol treatment. After 10 weeks, myographs were used to test the reactivity of isolated thoracic aortic rings to norepinephrine and acetylcholine. Thereafter, the vascular rings were incubated with the NO-synthase blocker (nitro-L-arginine methyl ester) or the cyclooxygenase inhibitor (indomethacin) for 20 min, and the effects of norepinephrine and acetylcholine were re-evaluated. RESULTS: Norepinephrine-induced vasoconstriction was enhanced after DHT treatment, but this effect was attenuated by calcitriol administration. Vasorelaxation of DHT-treated thoracic aortic rings was impaired, but this could be partly reversed by calcitriol application. Impaired NO-dependent vasorelaxation in DHT-treated animals was mostly reversed by concomitant calcitriol administration, but this effect was diminished by prostanoid-dependent vasoconstriction. CONCLUSIONS: These studies show that the enhanced sensitivity to vasoconstrictors and impaired NO-dependent vasorelaxation in hyperandrogenic PCOS rats could be partially reversed by calcitriol treatment

Effects of vitamin D3 derivative--calcitriol on pharmacological reactivity of aortic rings in a rodent PCOS model.

Abstract BACKGROUND: The aim of this study was to examine the effects of the hyperandrogenic state in dihydrotestosterone (DHT)-induced polycystic ovary syndrome (PCOS), the vascular responses to different vasoactive agents, and the modulatory role of vitamin D3. METHODS: APCOS model was induced by DHT application in 20 female Wistar rats. Ten of the DHT treated rats simultaneously received calcitriol treatment. After 10 weeks, myographs were used to test the reactivity of isolated thoracic aortic rings to norepinephrine and acetylcholine. Thereafter, the vascular rings were incubated with the NO-synthase blocker (nitro-L-arginine methyl ester) or the cyclooxygenase inhibitor (indomethacin) for 20 min, and the effects of norepinephrine and acetylcholine were re-evaluated. RESULTS: Norepinephrine-induced vasoconstriction was enhanced after DHT treatment, but this effect was attenuated by calcitriol administration. Vasorelaxation of DHT-treated thoracic aortic rings was impaired, but this could be partly reversed by calcitriol application. Impaired NO-dependent vasorelaxation in DHT-treated animals was mostly reversed by concomitant calcitriol administration, but this effect was diminished by prostanoid-dependent vasoconstriction. CONCLUSIONS: These studies show that the enhanced sensitivity to vasoconstrictors and impaired NO-dependent vasorelaxation in hyperandrogenic PCOS rats could be partially reversed by calcitriol treatment

Perivascular Expression and Potent Vasoconstrictor Effect of Dynorphin A in Cerebral Arteries

BACKGROUND: Numerous literary data indicate that dynorphin A (DYN-A) has a significant impact on cerebral circulation, especially under pathophysiological conditions, but its potential direct influence on the tone of cerebral vessels is obscure. The aim of the present study was threefold: 1) to clarify if DYN-A is present in cerebral vessels, 2) to determine if it exerts any direct effect on cerebrovascular tone, and if so, 3) to analyze the role of κ-opiate receptors in mediating the effect. METHODOLOGY/PRINCIPAL FINDINGS: Immunohistochemical analysis revealed the expression of DYN-A in perivascular nerves of rat pial arteries as well as in both rat and human intraparenchymal vessels of the cerebral cortex. In isolated rat basilar and middle cerebral arteries (BAs and MCAs) DYN-A (1-13) and DYN-A (1-17) but not DYN-A (1-8) or dynorphin B (DYN-B) induced strong vasoconstriction in micromolar concentrations. The maximal effects, compared to a reference contraction induced by 124 mM K(+), were 115±6% and 104±10% in BAs and 113±3% and 125±9% in MCAs for 10 µM of DYN-A (1-13) and DYN-A (1-17), respectively. The vasoconstrictor effects of DYN-A (1-13) could be inhibited but not abolished by both the κ-opiate receptor antagonist nor-Binaltorphimine dihydrochloride (NORBI) and blockade of G(i/o)-protein mediated signaling by pertussis toxin. Finally, des-Tyr(1) DYN-A (2-13), which reportedly fails to activate κ-opiate receptors, induced vasoconstriction of 45±11% in BAs and 50±5% in MCAs at 10 µM, which effects were resistant to NORBI. CONCLUSION/SIGNIFICANCE: DYN-A is present in rat and human cerebral perivascular nerves and induces sustained contraction of rat cerebral arteries. This vasoconstrictor effect is only partly mediated by κ-opiate receptors and heterotrimeric G(i/o)-proteins. To our knowledge our present findings are the first to indicate that DYN-A has a direct cerebral vasoconstrictor effect and that a dynorphin-induced vascular action may be, at least in part, independent of κ-opiate receptors

Characterization of Native and Human Serum Albumin-Bound Lysophosphatidic Acid Species and Their Effect on the Viability of Mesenchymal Stem Cells In Vitro

Scaffolds can provide a healthy environment for cell attachment, differentiation, proliferation, and migration in vitro and in vivo. Lysophosphatidic acid (LPA) is a naturally occurring bioactive phospholipid that is present in the serum mainly bound to albumin. The present study aims to investigate the biocompatibility of LPA. It also aims to determine the effect of different LPA species on the proliferation and migration of human bone marrow-derived mesenchymal stem cells (hBM-dMSCs) for LPA and human serum albumin (HSA) containing bone scaffold development. The HSA-LPA complex formation was assessed using Fourier-transform infrared (FTIR) spectroscopy. The effect of 18:1, 18:2, or 16:0 LPA alone, or in combination with 4% HSA, on cell viability and proliferation was determined by XTT. The cell migration was examined in a wound healing assay. The changes in the FTIR spectra of LPA-HSA compositions, compared with HSA alone, indicate the complex formation between the components. Our study showed that 18:1, 18:2, and 16:0 LPA species had no cytotoxic effects up to 10 µM concentration. The different LPA species increased the proliferation of hBM-dMSCs in a dose-dependent manner when administered in the presence of HSA, without an effect on the migration of this cell type. These findings make the in vivo application of LPA-HSA complex promising for bone regeneration

Dynorphin A (DYN-A) induced cerebral vasoconstriction is partly mediated by heterotrimeric G_i/o-proteins.

<p>Effect of the inhibition of G_i/o-signaling with pertussis toxin (PTX, applied as described in “<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037798#s2" target="_blank">Methods</a>”) on the responsiveness of rat basilar (A) and middle cerebral (B) arteries to DYN-A (1–13). In control vessels the slightly weaker reactions to DYN-A (as compared to the previous figures) were probably the consequence of overnight incubation in the Krebs solution containing the vehicle of PTX. PTX inhibited the vasoconstrictor effects of DYN-A. Values are expressed as mean±SEM percentage of the reference contraction induced by 124 mmol/L K⁺ Krebs solution, n = 6–8. Asterisks indicate significant (*<i>P</i><0.05, **<i>P</i><0.01) differences between PTX-treated and vehicle-treated control vessels.</p

Dynorphin A (DYN-A) (1–13) and (1–17) induce strong contraction of rat cerebral arteries.

<p>Effects of cumulative concentrations of DYN-A (1–8), (1–13), (1–17) and Dynorphin B (DYN-B) on the resting tension of rat basilar (A) and middle cerebral (B) arteries. DYN-A (1–13) and DYN-A (1–17) induce strong, dose-dependent vasoconstriction in both vessels, whereas DYN-A (1–8) and DYN-B have no significant effect. Values are expressed as mean±SEM percentage of the reference contraction induced by 124 mmol/L K⁺ Krebs solution, n = 6–37. *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001 vs. DYN-A (1–8); ^##<i>P</i><0.01, ^###<i>P</i><0.001 vs. DYN-B.</p

Dynorphin A (DYN-A) induced cerebral vasoconstriction is partly mediated by κ-opiate receptors.

<p>Effect of the κ-opiate receptor antagonist <i>nor</i>-Binaltorphimine dihydrochloride (NORBI, 50 µM) on the responsiveness of rat basilar (A) and middle cerebral (B) arteries to DYN-A (1–13). NORBI was able to reduce the vasoconstrictor effect of DYN-A in both vessels, whereas its vehicle (saline) was without any effect (C and D). Values are expressed as mean±SEM percentage of the reference contraction induced by 124 mmol/L K⁺ Krebs solution, n = 8–10. Asterisks indicate significant (**<i>P</i><0.01, ***<i>P</i><0.001) differences between values before and after NORBI treatment.</p