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Johnson AC, Miller JE, Cipolla MJ. Memory impairment in spontaneously hypertensive rats is associated with hippocampal hypoperfusion and hippocampal vascular dysfunction. J Cereb Blood Flow Metab 2020; 40:845-859. [PMID: 31088235 PMCID: PMC7168795 DOI: 10.1177/0271678x19848510] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We investigated the effect of chronic hypertension on hippocampal arterioles (HippAs) and hippocampal perfusion as underlying mechanisms of memory impairment, and how large artery stiffness relates to HippA remodeling. Using male spontaneously hypertensive rats (SHR) and normotensive Wistar rats (n = 12/group), long-term (LTM) and spatial memory were tested using object recognition and spontaneous alternation tasks. Hippocampal blood flow was measured via hydrogen clearance basally and during hypercapnia. Reactivity of isolated and pressurized HippAs to pressure and pharmacological activators and inhibitors was investigated. To determine large artery stiffness, distensibility and elastin content were measured in thoracic aorta. SHR had impaired LTM and spatial memory associated with decreased basal blood flow (68 ± 12 mL/100 g/min) vs. Wistar (111 ± 28 mL/100 g/min, p < 0.01) that increased during hypercapnia similarly between groups. Compared to Wistar, HippAs from SHR had increased tone at 60 mmHg (58 ± 9% vs. 37 ± 7%, p < 0.01), and decreased reactivity to small- and intermediate-conductance calcium-activated potassium (SK/IK) channel activation. HippAs in both groups were unaffected by NOS inhibition. Decreased elastin content correlated with increased stiffness in aorta of SHR that was associated with increased stiffness and hypertrophic remodeling of HippAs. Hippocampal vascular dysfunction during hypertension could potentiate memory deficits and may provide a therapeutic target to limit vascular cognitive impairment.
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Johnson AC, Li Z, Orfila JE, Herson PS, Cipolla MJ. Experimental Preeclampsia Causes Persistent Impairment of Hippocampal‐Dependent Memory and Network Function that is Exacerbated by Status Convulsions. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.02034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Li Z, Lindner D, Cipolla MJ. Abstract 138: Angiotensin Converting Enzyme (ACE) Inhibition Reverses Vasoconstriction and Impaired Dilation of Pial Collaterals During Chronic Hypertension. Stroke 2020. [DOI: 10.1161/str.51.suppl_1.138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Introduction:
Leptomeningeal anastomoses (LMAs) are pial collaterals that perfuse the penumbra and are important for stroke outcome. In the current study, we investigated mechanisms by which hypertension causes LMA vasoconstriction that is known to limit the amount of salvageable tissue when stroke occurs during chronic hypertension. We hypothesized that increased vasoreactivity of LMAs from hypertensive rats is angiotensin II (Ang II)-dependent.
Methods:
Spontaneously hypertensive rats (SHRs, n=8/group) were treated with the ACE inhibitor captopril, hydralazine to lower blood pressure (BP) independent of AngII, or vehicle for 5 weeks in drinking water. A group of normotensive Wistar rats (n=8) had regular drinking water served as controls. BP was measured twice weekly by tail cuff. LMAs were isolated and studied in pressurized conditions. Vasoactivity of LMAs, including myogenic responses, reactivity to the Rho-kinase inhibitor Y-27632 and nitric oxide (NO) were measured.
Results:
Both captopril and hydralazine lowered BP in SHRs similar to Wistar rats. LMAs from untreated SHRs had increased myogenic tone vs. Wistar that was normalized by captopril but not hydralazine (Fig. 1A). LMAs from all groups constricted similarly to NO synthase inhibition; however, the vasodilatory response of LMAs to the NO donor sodium nitroprusside, was impaired in SHRs vs. Wistar rats that was restored by captopril and not hydralazine (Fig. 1B). Maximum vasodilatory response of LMAs to Y-27632 was impaired in SHRs compared to Wistar rats (28±3% vs. 81±4%, p<0.01) that was restored by captopril (84±5%) and partially by hydralazine (59±4%) treatment.
Conclusions:
ACE inhibition during chronic hypertension reversed vascular dysfunction and hyperconstriction of LMAs, an effect that could improve stroke outcome by increasing collateral perfusion. In addition, lowering BP alone without inhibition of Ang II, may not provide the same protective effect on pial collaterals.
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Abstract
Perinatal stroke is a heterogeneous syndrome resulting from brain injury of vascular origin that occurs between 20 weeks of gestation and 28 days of postnatal life. The incidence of perinatal stroke is estimated to be between 1:1600 and 1:3000 live births (approximately 2500 children per year in the United States), though its actual incidence is difficult to estimate because it is likely underdiagnosed. Perinatal arterial ischemic stroke (PAIS) accounts for approximately 70% of cases of perinatal stroke. Cerebral sinovenous thrombosis, while less common, also accounts for a large proportion of the morbidity and mortality seen with perinatal stroke. Hemorrhagic stroke leads to disruption of neurologic function due to intracerebral hemorrhage that is nontraumatic in origin. While most cases of PAIS fall into one of these three categories, other patterns of injury should also be considered perinatal stroke. In some cases, the etiology of PAIS is not known but is idiopathic. This chapter will review the classification, risk factors, pathogenesis, clinical presentation, management, and long-term sequelae of perinatal stroke.
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Chan SL, Bishop N, Li Z, Cipolla MJ. Inhibition of PAI (Plasminogen Activator Inhibitor)-1 Improves Brain Collateral Perfusion and Injury After Acute Ischemic Stroke in Aged Hypertensive Rats. Stroke 2019; 49:1969-1976. [PMID: 29991657 DOI: 10.1161/strokeaha.118.022056] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Background and Purpose- Aging and hypertension, comorbidities prevalent in the stroke population, are associated with poor collateral status and worsened stroke outcome. However, underlying mechanisms by which these conditions affect stroke outcome are not clear. We studied the role of PAI (plasminogen activator inhibitor)-1 that is increased in aging and hypertension on brain and vascular expression of inflammatory factors and perfusion that may contribute to worse stroke outcomes. Methods- Aged (≈50 weeks) and young (≈18 weeks) spontaneously hypertensive rats (SHR) were subjected to ischemia by middle cerebral artery occlusion (2 hours) and reperfusion (2 hours) with or without treatment with the PAI-1 inhibitor TM5441. Changes in middle cerebral artery and collateral perfusion territories were measured by multisite laser Doppler. Reactivity to TM5441 was studied using isolated and pressurized leptomeningeal anastomotic arterioles. Brain injury was determined by 2,3,5-triphenyltetrazolium staining and quantitative immunohistochemistry of amyloid-β-42, PAI-1, and hemoglobin. Circulating inflammatory factors were measured by ELISA. Results- Changes in cerebral blood flow during middle cerebral artery occlusion were similar between groups, with both having poor collateral perfusion and incomplete reperfusion. However, aged SHR had greater brain injury versus young (41±2 versus 23±2%, P<0.05) as well as increased brain deposition of amyloid-β-42 and circulating oxLDL (oxidized low-density lipoprotein). Erythrocyte aggregation and hemorrhage within the injured brain was observed in 50% of aged but no young SHR, with increased circulating PAI-1 in this subgroup of aged SHR (16±3 versus 6±2 ng/mL, P<0.05). PAI-1 inhibition with TM5441 improved brain injury but did not affect hemorrhage. TM5441 increased collateral perfusion by 38±7% and dilated leptomeningeal anastomotic arterioles by 44±10%, which was abolished by nitric oxide synthase inhibition. Conclusions- Increased injury in aged SHR seemed to be related to poor collateral perfusion, hemorrhagic transformation, increased amyloid-β-42, and oxidative stress. PAI-1 inhibition reduced infarction in both groups of SHR that possibly due, in part, to increased collateral perfusion.
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Herisson F, Zhou I, Mawet J, Du E, Barfejani AH, Qin T, Cipolla MJ, Sun PZ, Rost NS, Ayata C. Posterior reversible encephalopathy syndrome in stroke-prone spontaneously hypertensive rats on high-salt diet. J Cereb Blood Flow Metab 2019; 39:1232-1246. [PMID: 29350576 PMCID: PMC6668522 DOI: 10.1177/0271678x17752795] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Stroke-prone spontaneously hypertensive rats (SHRSP) on high-salt diet are characterized by extremely high arterial pressures, and have been endorsed as a model for hypertensive small vessel disease and vascular cognitive impairment. However, rapidly developing malignant hypertension is a well-known cause of posterior reversible encephalopathy syndrome (PRES) in humans, associated with acute neurological deficits, seizures, vasogenic cerebral edema and microhemorrhages. In this study, we aimed to examine the overlap between human PRES and SHRSP on high-salt diet. In SHRSP, arterial blood pressure progressively increased after the onset of high-salt diet and seizure-like signs emerged within three to five weeks. MRI revealed progressive T2-hyperintense lesions suggestive of vasogenic edema predominantly in the cortical watershed and white matter regions. Histopathology confirmed severe blood-brain barrier disruption, white matter vacuolization and microbleeds that were more severe posteriorly. Hematological data suggested a thrombotic microangiopathy as a potential underlying mechanism. Unilateral common carotid artery occlusion protected the ipsilateral hemisphere from neuropathological abnormalities. Notably, all MRI and histopathological abnormalities were acutely reversible upon switching to regular diet and starting antihypertensive treatment. Altogether our data suggest that SHRSP on high-salt diet recapitulates the neurological, histopathological and imaging features of human PRES rather than chronic progressive small vessel disease.
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Chan SL, Nelson MT, Cipolla MJ. Transient receptor potential vanilloid-4 channels are involved in diminished myogenic tone in brain parenchymal arterioles in response to chronic hypoperfusion in mice. Acta Physiol (Oxf) 2019; 225:e13181. [PMID: 30153398 DOI: 10.1111/apha.13181] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 12/11/2022]
Abstract
AIM Adaptive responses of brain parenchymal arterioles (PAs), a target for cerebral small vessel disease, to chronic cerebral hypoperfusion are largely unknown. Previous evidence suggested that transient receptor potential vanilloid 4 channels may be involved in the regulation of cerebrovascular tone. Therefore, we investigated the role of TRPV4 in adaptations of PAs in a mouse model of chronic hypoperfusion. METHODS TRPV4 knockout (-/- ) and wild-type (WT) mice were subjected to unilateral common carotid artery occlusion (UCCAo) for 28 days. Function and structure of PAs ipsilateral to UCCAo were studied isolated and pressurized in an arteriograph. RESULTS Basal tone of PAs was similar between WT and TRPV4-/- mice (22 ± 3 vs 23 ± 5%). After UCCAo, active inner diameters of PAs from WT mice were larger than control (41 ± 2 vs 26 ± 5 μm, P < 0.05) that was due to decreased tone (8 ± 2 vs 23 ± 5%, P < 0.05), increased passive inner diameters (46 ± 3 vs 34 ± 2 μm, P < 0.05), and decreased wall-to-lumen ratio (0.104 ± 0.01 vs 0.137 ± 0.01, P < 0.05). However, UCCAo did not affect vasodilation to a small- and intermediate-conductance calcium-activated potassium channel agonist NS309, the nitric oxide (NO) donor sodium nitroprusside, or constriction to a NO synthase inhibitor L-NNA. Wall thickness and distensibility in PAs from WT mice were unaffected. In TRPV4-/- mice, UCCAo had no effect on active inner diameters or tone and only increased passive inner diameters (53 ± 2 vs 43 ± 3 μm, P < 0.05). CONCLUSION Adaptive response of PAs to chronic cerebral hypoperfusion includes myogenic tone reduction and outward remodelling. TRPV4 channels were involved in tone reduction but not outward remodelling in response to UCCAo.
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Cipolla MJ, Liebeskind DS, Chan SL. The importance of comorbidities in ischemic stroke: Impact of hypertension on the cerebral circulation. J Cereb Blood Flow Metab 2018; 38:2129-2149. [PMID: 30198826 PMCID: PMC6282213 DOI: 10.1177/0271678x18800589] [Citation(s) in RCA: 180] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Comorbidities are a hallmark of stroke that both increase the incidence of stroke and worsen outcome. Hypertension is prevalent in the stroke population and the most important modifiable risk factor for stroke. Hypertensive disorders promote stroke through increased shear stress, endothelial dysfunction, and large artery stiffness that transmits pulsatile flow to the cerebral microcirculation. Hypertension also promotes cerebral small vessel disease through several mechanisms, including hypoperfusion, diminished autoregulatory capacity and localized increase in blood-brain barrier permeability. Preeclampsia, a hypertensive disorder of pregnancy, also increases the risk of stroke 4-5-fold compared to normal pregnancy that predisposes women to early-onset cognitive impairment. In this review, we highlight how comorbidities and concomitant disorders are not only risk factors for ischemic stroke, but alter the response to acute ischemia. We focus on hypertension as a comorbidity and its effects on the cerebral circulation that alters the pathophysiology of ischemic stroke and should be considered in guiding future therapeutic strategies.
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Li Z, Tremble SM, Cipolla MJ. Implications for understanding ischemic stroke as a sexually dimorphic disease: the role of pial collateral circulations. Am J Physiol Heart Circ Physiol 2018; 315:H1703-H1712. [PMID: 30239233 DOI: 10.1152/ajpheart.00402.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We investigated structural and functional differences in primary and pial collateral circulations in adult normotensive male and female Wistar rats. Male ( n = 10) and female ( n = 7) rats were subjected to middle cerebral artery (MCA) occlusion and changes in relative cerebral blood flow in MCA and pial collateral territories were measured by multisite laser-Doppler flowmetry. Rats were then transcardially perfused with a mixture of carbon black and latex, perfusion fixed, and imaged to compare primary and pial collateral structure between male ( n = 4) and female ( n = 3) rats, including lumen diameters and number. To study pial collateral function, leptomeningeal anastomoses (LMAs) were isolated and pressurized from male ( n = 7) and female ( n = 6) rats. Myogenic tone and reactivity to pressure, vascular function to pharmacological activator, or inhibitor of ion channels was measured and compared. There was no difference between relative cerebral blood flow in both MCA and pial collateral territories during occlusion and reperfusion between groups. Compared with male LMAs, female LMAs had similar myogenic tone (24.0 ± 7.3% vs. 16.0 ± 3.7%, P > 0.05) and reactivity to increased pressure and similar vascular responses to vasoconstrictive and vasodilatory stimuli. Additionally, compared with female LMAs, male LMAs had similar numbers (21 ± 1 vs. 20 ± 2, P > 0.05) and diameters (30.5 ± 2.0 vs. 26.2 ± 0.6 μm, P > 0.05), and no sex difference was detected in the diameter of arterial segments of circle of Willis. Together, our data establish no sex difference of cerebral collateral structure or function, suggesting that the reduced severity of stroke outcome in female rats is not likely due to differences in the cerebral collateral circulation. NEW & NOTEWORTHY Our work compared the function of leptomeningeal anastomoses between male and female adult normotensive rats with no sex difference found. We also confirmed no sex difference in primary and pial collateral structure in Wistar rats. Our findings suggest that the reduced severity of stroke in premenopausal women and reproductively intact female rodents is not likely due to improved primary and pial collateral circulations.
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Merhi Z, Buyuk E, Cipolla MJ. Advanced glycation end products alter steroidogenic gene expression by granulosa cells: an effect partially reversible by vitamin D. Mol Hum Reprod 2018; 24:318-326. [PMID: 29538679 PMCID: PMC6530817 DOI: 10.1093/molehr/gay014] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 02/28/2018] [Accepted: 03/08/2018] [Indexed: 12/21/2022] Open
Abstract
STUDY QUESTION Does vitamin D attenuate the adverse effects of advanced glycation end products (AGEs) on steroidogenesis by human granulosa cells (GCs)? SUMMARY ANSWER AGEs alter the expression of genes important in steroidogenesis while 1,25-dihydroxyvitamin D3 (vit D3) in vitro attenuates some of the actions of AGEs on steroidogenic gene expression, possibly by downregulating the expression of the pro-inflammatory cell membrane receptor for AGEs (RAGE). WHAT IS KNOWN ALREADY Vitamin D attenuates the pro-inflammatory effects of AGEs in non-ovarian tissues. STUDY DESIGN, SIZE, DURATION Women who were undergoing IVF were enrolled. Follicular fluid samples (n = 71) were collected and cumulus GCs (n = 12) were treated in culture. PARTICIPANTS/MATERIALS, SETTING, METHODS Follicular fluid levels of the anti-inflammatory soluble RAGE (sRAGE), AGEs and 25-hydroxyvitamin D (25-OHD) were quantified for possible correlations. GCs of each participant were split equally and treated with either media alone (control) or with human glycated albumin (HGA as a precursor for AGEs) with or without vit D3 after which RT-PCR and immunofluorescence were performed and cell culture media estradiol (E2) levels were compared. MAIN RESULTS AND THE ROLE OF CHANCE In follicular fluid, sRAGE levels were positively correlated with 25-OHD levels. HGA treatment (i) increased CYP11A1 (by 48%), 3β-HSD (by 38%), StAR (by 42%), CYP17A1 (by 30%) and LHR (by 37%) mRNA expression levels (P < 0.05 for all) but did not alter CYP19A1 or FSHR mRNA expression levels; and (ii) increased E2 release in cell culture media (P = 0.02). Vit D3 treatment (i) downregulated RAGE mRNA expression by 33% and RAGE protein levels by 44% (P < 0.05); (ii) inhibited the HGA-induced increase in CYP11A1, StAR, CYP17A1 and LHR mRNA levels, but not the increase in 3β-HSD mRNA levels; and (iii) did not inhibit the HGA-induced E2 release in cell culture media. LIMITATIONS REASONS FOR CAUTION This study used luteinized GCs that were collected from women who received gonadotropins thus the results obtained may not fully extrapolate to non-luteinized GCs in vivo. WIDER IMPLICATIONS OF THE FINDINGS This study suggests that there is a relationship between AGEs and their receptors (RAGE and sRAGE) with vitamin D. Understanding the interaction between AGEs and vitamin D in ovarian physiology could lead to a more targeted therapy for the treatment of ovarian dysfunction. STUDY FUNDING/COMPETING INTEREST(S) Funding was received from NIH (R01 NS045940), American Society for Reproductive Medicine, Ferring Pharmaceuticals Inc., and University of Vermont College of Medicine Bridge Funds. All authors have nothing to disclose.
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Cipolla MJ, Linfante I, Abuchowski A, Jubin R, Chan SL. Pharmacologically increasing collateral perfusion during acute stroke using a carboxyhemoglobin gas transfer agent (Sanguinate™) in spontaneously hypertensive rats. J Cereb Blood Flow Metab 2018; 38:755-766. [PMID: 28436705 PMCID: PMC5987934 DOI: 10.1177/0271678x17705567] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Similar to patients with chronic hypertension, spontaneously hypertensive rats (SHR) develop fast core progression during middle cerebral artery occlusion (MCAO) resulting in large final infarct volumes. We investigated the effect of Sanguinate™ (SG), a PEGylated carboxyhemoglobin (COHb) gas transfer agent, on changes in collateral and reperfusion cerebral blood flow and brain injury in SHR during 2 h of MCAO. SG (8 mL/kg) or vehicle ( n = 6-8/group) was infused i.v. after 30 or 90 min of ischemia with 2 h reperfusion. Multi-site laser Doppler probes simultaneously measured changes in core MCA and collateral flow during ischemia and reperfusion using a validated method. Brain injury was measured using TTC. Animals were anesthetized with choral hydrate. Collateral flow changed little in vehicle-treated SHR during ischemia (-8 ± 9% vs. prior to infusion) whereas flow increased in SG-treated animals (29 ± 10%; p < 0.05). In addition, SG improved reperfusion regardless of time of treatment; however, brain injury was smaller only with early treatment in SHR vs. vehicle (28.8 ± 3.2% vs. 18.8 ± 2.3%; p < 0.05). Limited collateral flow in SHR during MCAO is consistent with small penumbra and large infarction. The ability to increase collateral flow in SHR with SG suggests that this compound may be useful as an adjunct to endovascular therapy and extend the time window for treatment.
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Johnson AC, Cipolla MJ. Impaired function of cerebral parenchymal arterioles in experimental preeclampsia. Microvasc Res 2018; 119:64-72. [PMID: 29705580 DOI: 10.1016/j.mvr.2018.04.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 04/20/2018] [Accepted: 04/20/2018] [Indexed: 01/17/2023]
Abstract
Preeclampsia (PE), a dangerous hypertensive complication of pregnancy, is associated with widespread maternal vascular dysfunction. However, the effect of PE on the cerebral vasculature that can lead to stroke and cognitive decline is not well understood. We hypothesized that function of cortical parenchymal arterioles (PAs) would be impaired during PE. Using a high cholesterol diet to induce experimental PE in rats (ePE), we studied the function and structure of isolated and pressurized PAs supplying frontoparietal white matter (WM) tracts and cortex and compared to normal pregnant (Preg) and nonpregnant (Nonpreg) Sprague Dawley rats (n = 8/group). Myogenic reactivity and tone were similar between groups; however, constriction to intermediate-conductance calcium-activated potassium (IK) channel inhibition was diminished and dilation to inward-rectifying K+ (KIR) channel activation was impaired in PAs from ePE rats, suggesting altered ion channel function. Conducted vasodilation was significantly delayed in response to 12 mM KCl, but not 10 μM adenosine, in PAs from ePE rats versus Preg and Nonpreg rats (940 ± 300 ms vs. 70 ± 50 ms and 370 ± 90 ms; p < 0.05). Overall, dysfunction of PAs supplying frontoparietal WM and gray matter was present in ePE. If persistent these changes could potentiate neuronal injury that over time could contribute to WM lesions and early-onset cognitive decline.
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Chan SL, Liebeskind DS, Ayata C, Cipolla MJ. Abstract WP407: Function and Reactivity of Pial Collaterals In Vivo in Normotensive and Hypertensive Rats: Response to Ischemia and Reperfusion. Stroke 2018. [DOI: 10.1161/str.49.suppl_1.wp407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background:
Collateral therapeutics is an emerging treatment for acute ischemic stroke. However, whether pial collaterals have tone in vivo and thus the ability to vasodilate is not clear. We investigated the function of pial collaterals in vivo during ischemia and reperfusion in normotensive and hypertensive rats that are known to have poor collaterals. We hypothesized that pial collaterals from spontaneously hypertensive rats (SHR) would have greater basal tone during ischemia and reperfusion than normotensive Wistar rats that could contribute to decreased collateral perfusion.
Methods:
A cranial window was performed in SHR (n=4) and Wistar (n=4) rats prior to remote middle cerebral artery occlusion (MCAo) under pentobarbital anesthesia. Video microscopy was used to measure changes in diameter of leptomeningeal anastomoses (LMAs) during MCAo for 2 hrs and 2 hrs reperfusion (Figure, top). After reperfusion, the brain surface was exposed to physiological saline solution with EDTA (67 mmol/L) to measure fully relaxed diameters and calculate basal tone. Blood pressure was measured via arterial catheter and animals were mechanically ventilated to control blood gases.
Results:
Blood pressure was significantly elevated in SHR vs. Wistar rats (157±9 vs. 107±7; p<0.01). LMAs (~15-20 μm diameters) had basal tone that was higher in SHR vs. Wistar (15.4±9% vs. 8.4±4.9%; n.s.). After 5 min MCAo, tone in LMAs from Wistar rats decreased to 2.7±1.5% but increased to 17.2±9.7% in SHR. Reperfusion caused vasoconstriction of LMAs from both groups and increased tone to 18.7±5.3% in Wistar and to 29.5±9.7% in SHR (p<0.01 vs. basal for both; Figure, bottom).
Conclusions:
These data demonstrate functional pial collaterals in normotensive and hypertensive rats. While increased tone of LMAs during MCAo in SHR could limit perfusion to the penumbra, vasoconstriction of LMAs from both groups suggests therapeutic intervention to increase diameter and salvage at risk tissue is possible.
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Liebeskind DS, Ayata C, Brown S, Raychev R, Scalzo F, Broderick JP, Tomsick TA, Cipolla MJ. Abstract 79: Chronic and Acute Hypertension in Ischemic Stroke Are Distinct Markers of Impaired Collateral Circulation. Stroke 2018. [DOI: 10.1161/str.49.suppl_1.79] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background:
Acute blood pressure (BP) elevation in acute ischemic stroke (AIS) is common, yet the link with collateral circulation remains elusive due to lack of longitudinal data on premorbid hypertension (HTN) and serial BP changes within an individual. Precision medicine for AIS and management of HTN requires an understanding of collateral circulation.
Methods:
The Interventional Management of Stroke III angiography core lab prospectively evaluated collateral circulation utilizing the ASITN scale prior to endovascular therapy. We used these data to discern the relationship of clinical and imaging markers of premorbid HTN with acute, serial BP measures and collaterals.
Results:
Collaterals at angiography were graded in 276/331 (83%) subjects. Higher initial BP was associated with impaired collateral status, driven by diastolic BP (ASITN 0-1: mean 88.9 ± 23.5 mmHg (n=70); 2: 82.7 ± 18.5 mmHg (n=106); 3-4: 79.4 ± 15.0 mmHg (n=95); p=0.002) but not systolic BP (ASITN 0-1: mean 153.7 ± 31.5 mmHg (n=71); 2: 147.8 ± 29.0 mmHg (n=107); 3-4: 146.8 ± 28.3 mmHg (n=95); p=0.153). Premorbid HTN was linked with worse collaterals (ASITN 0-1: 88.9% (64/72); 2: 78.7% (85/108); 3-4: 64.2% (61/95); p=0.001). Admission anti-hypertensive medications were tied to worse collaterals (ASITN 0-1: 76.4% (55/72); 2: 64.8% (70/108); 3-4: 57.3% (55/96); p=0.036). Prior infarction on baseline imaging was also a marker of worse collaterals (ASITN 0-1: 33.3% (24/72); 2: 24.3% (26/107); 3-4: 19.1% (18/94); p=0.039). Serial BP from pre-randomization to post-tPA, however, was unrelated to collateral status. Multivariate modeling to predict collateral grade revealed that history of HTN (OR 0.29 95%CI (0.13, 0.64); p=0.002) and diastolic BP measured post-stroke but pre-randomization (per 10 mm Hg) (OR 0.80 95%CI (0.69, 0.93); p=0.004) were both distinct markers of impaired collaterals. The poorest collaterals were seen in those with both history of HTN and acutely elevated BP.
Conclusions:
Chronic and acute HTN are both potent predictors of impaired collaterals in AIS. Understanding how HTN affects the structure and function of collaterals and response to acute BP changes is critical for future hypertensive management and collateral augmentation.
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Johnson AC, Hammer ES, Sakkaki S, Tremble SM, Holmes GL, Cipolla MJ. Inhibition of blood-brain barrier efflux transporters promotes seizure in pregnant rats: Role of circulating factors. Brain Behav Immun 2018; 67:13-23. [PMID: 28739514 PMCID: PMC5696046 DOI: 10.1016/j.bbi.2017.07.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 07/18/2017] [Accepted: 07/20/2017] [Indexed: 11/17/2022] Open
Abstract
Seizure-provoking factors circulate late in gestation during normal pregnancy, but do not readily gain access to the brain due to the protective nature of the blood-brain barrier. In particular, efflux transporters are powerful ATP-driven pumps that actively prevent unwanted compounds from entering the brain. We hypothesized that acute inhibition of efflux transporters at the blood-brain barrier would result in spontaneous seizures in pregnant rats. We further hypothesized that the blood-brain barrier protects the maternal brain from seizure by increasing expression and/or activity of p-glycoprotein (P-gp), a major efflux transporter. Main blood-brain barrier efflux transporters were inhibited in-vivo in nonpregnant (Nonpreg) and pregnant (Preg; d19) Sprague Dawley rats (n=8/group). Seizures were monitored in conscious animals for 8h via chronically implanted electroencephalography (EEG) electrodes in the hippocampus and motor cortex and time-synced video. P-gp activity was measured via a calcein accumulation assay in freshly isolated cortical and hippocampal capillaries from Preg (d20) and Nonpreg rats (n=8-16/group), to assess regional susceptibility to transporter inhibition. P-gp expression, capillary density, and microglial activation as a measure of neuroinflammation were quantified using immunohistochemistry (n=4-6/group). Efflux transporter inhibition elicited hippocampal seizures within 1h in 100% of Preg rats that was not associated with neuroinflammation or elevated tumor necrosis factor alpha (TNFα) or vascular endothelial growth factor (VEGF), but negatively correlated with levels of estradiol. Hippocampal seizures were considerably less prevalent in Nonpreg rats. However, behavioral seizures in the motor cortex developed of similar severity in both groups of rats, demonstrating regional heterogeneity in response to efflux transporter inhibition. Basal P-gp activity was similar between groups, however, exposure to serum from Preg rats significantly decreased P-gp activity in the hippocampus, but not cortex, compared to serum from Nonpreg rats (0.29±0.1units/s in Preg vs. 0.06±0.02units/s in Nonpreg rats; p<0.05) that was not associated with elevated TNFα or VEGF. Thus, pregnancy differentially increased the susceptibility of the hippocampus to seizures in response to blood-brain barrier efflux transporter inhibition that may be due to the inhibitory effect of circulating factors in pregnancy on P-gp activity in the hippocampus.
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Chan SL, Cipolla MJ. Treatment with low dose fasudil for acute ischemic stroke in chronic hypertension. J Cereb Blood Flow Metab 2017; 37:3262-3270. [PMID: 28665172 PMCID: PMC5584704 DOI: 10.1177/0271678x17718665] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigated the effect of Rho kinase inhibition on changes in cerebral blood flow (CBF), brain injury and vascular function after ischemic stroke in spontaneously hypertensive rats (SHR). Changes in core MCA and collateral perfusion were measured by a validated laser Doppler method. Animals underwent 2 h tMCAO and 2 h reperfusion. Fasudil (0.1 mg/kg, i.v.) or vehicle was given at 30 min ischemia (n = 9/group; mean (SD)). Brain injury was determined by 2,3,5-triphenyltetrazolium chloride staining. To determine the effect of fasudil on vascular function, fasudil was given 10 min before reperfusion and parenchymal arterioles studied isolated (n = 6/group; mean(SD)). Collateral perfusion was low in vehicle-treated SHR (-8(32)%) that changed minimally with fasudil (6(24)%, p > 0.05, effect size: 0.47;95% CI-0.49-1.39). Reperfusion CBF was below baseline in vehicle (-27(26)%) and fasudil (-32(25)%, p > 0.05, effect size: 0.19; 95% CI-0.74-1.11) groups, suggesting incomplete reperfusion in both groups. Fasudil had little effect on brain injury volume (28(13)% vs. 36(7)% in vehicle, p > 0.05, effect size: 0.75; 95% CI-0.24-1.66). In isolated parenchymal arterioles, myogenic tone was similar between groups (37(6)% vs. 38(10)% in vehicle, p > 0.05, effect size: 0.09; 95% CI-1.05-1.21). There were no differences with fasudil treatment vs. vehicle in perfusion, brain injury and vascular function that may be related to the low dose that had minimal blood pressure lowering effect.
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Johnson AC, Cipolla MJ. Altered hippocampal arteriole structure and function in a rat model of preeclampsia: Potential role in impaired seizure-induced hyperemia. J Cereb Blood Flow Metab 2017; 37:2857-2869. [PMID: 27815419 PMCID: PMC5536792 DOI: 10.1177/0271678x16676287] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigated the effect of experimental preeclampsia on hyperemia during seizure in the hippocampus and vascular function and structure of hippocampal arterioles using Sprague Dawley rats (n = 14/group) that were nonpregnant, pregnant (d20), or had experimental preeclampsia (induced by a high cholesterol diet d7-20). Hyperemia was measured via hydrogen clearance basally and during pentylenetetrazol-induced seizure (40-130 mg/kg i.v.). Reactivity of isolated and pressurized hippocampal arterioles to KCl, nitric oxide synthase inhibition with NG-nitro-L-arginine methyl ester and the nitric oxide donor sodium nitroprusside were investigated. Capillary density was quantified via immunohistochemistry. Cerebral blood flow increased during seizure vs. baseline in pregnant (118 ± 14 vs. 87 ± 9 mL/100 g/min; p < 0.05) and nonpregnant rats (106 ± 9 vs. 82 ± 9 mL/100 g/min; p < 0.05) but was unchanged in preeclamptic rats (79 ± 16 vs. 91 ± 4 mL/100 g/min; p > 0.05), suggesting impaired seizure-induced hyperemia in preeclampsia. Hippocampal arterioles from preeclamptic rats had less basal tone, and dilated less to 15 mM KCl (9 ± 8%) vs. pregnant (61 ± 27%) and nonpregnant rats (20 ± 11%). L-NAME had no effect on hippocampal arterioles in any group, but dilation to sodium nitroprusside was similar. Structurally, hippocampal arterioles from preeclamptic rats underwent inward hypotrophic remodeling and capillary rarefaction. Impaired seizure-induced hyperemia, vascular dysfunction, and limited vasodilatory reserve of hippocampal arterioles could potentiate hippocampal injury in preeclampsia especially during eclampsia.
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Bosetti F, Koenig JI, Ayata C, Back SA, Becker K, Broderick JP, Carmichael ST, Cho S, Cipolla MJ, Corbett D, Corriveau RA, Cramer SC, Ferguson AR, Finklestein SP, Ford BD, Furie KL, Hemmen TM, Iadecola C, Jakeman LB, Janis S, Jauch EC, Johnston KC, Kochanek PM, Kohn H, Lo EH, Lyden PD, Mallard C, McCullough LD, McGavern LM, Meschia JF, Moy CS, Perez-Pinzon MA, Ramadan I, Savitz SI, Schwamm LH, Steinberg GK, Stenzel-Poore MP, Tymianski M, Warach S, Wechsler LR, Zhang JH, Koroshetz W. Translational Stroke Research: Vision and Opportunities. Stroke 2017; 48:2632-2637. [PMID: 28751554 DOI: 10.1161/strokeaha.117.017112] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 04/20/2017] [Accepted: 05/01/2017] [Indexed: 11/16/2022]
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Cipolla MJ, Sweet JG, Chan SL. Effect of hypertension and peroxynitrite decomposition with FeTMPyP on CBF and stroke outcome. J Cereb Blood Flow Metab 2017; 37:1276-1285. [PMID: 27317653 PMCID: PMC5453450 DOI: 10.1177/0271678x16654158] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
We investigated the effect of peroxynitrite decomposition catalyst FeTMPyP treatment on perfusion deficit, vascular function and stroke outcome in Wistar ( n = 26) and spontaneously hypertensive rats stroke-prone (SHRSP; n = 26) that underwent tMCAO for 2 h or Sham operation. Peri-infarct CBF was measured by hydrogen clearance in the absence or presence of FeTMPyP (10 mg/kg, i.v.) or vehicle 10 min before reperfusion. Myogenic tone of parenchymal arterioles (PAs) was measured as an indication of small vessel resistance (SVR). Baseline CBF was similar between Wistar and SHRSP (114 ± 12 vs. 132 ± 9 mL/100 g/min); however, MCAO caused greater perfusion deficit in SHRSP (24 ± 6 vs. 7 ± 1 mL/100 g/min; p < 0.05) and increased infarct volume by TTC (12 ± 6 vs. 32 ± 2%; p < 0.05). Reperfusion CBF was decreased from baseline in both SHRSP and Wistar (54 ± 16 and 46 ± 19 mL/100 g/min; p < 0.05), suggesting increased infarction in SHRSP was related to greater perfusion deficit. PAs from SHRSP had increased tone vs. Wistar that was enhanced after tMCAO. FeTMPyP treatment did not affect CBF during ischemia or reperfusion, or tone of PAs, but decreased the incidence of hemorrhage in SHRSP by 50%. Thus, increased tone in PAs from SHRSP could increase perfusion deficit during MCAO that was not alleviated by FeTMPyP.
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Cipolla MJ, Biller J. Persistent brain injury after preeclampsia. Neurology 2017; 88:1216-1217. [PMID: 28235812 DOI: 10.1212/wnl.0000000000003773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Bosetti F, Galis ZS, Bynoe MS, Charette M, Cipolla MJ, Del Zoppo GJ, Gould D, Hatsukami TS, Jones TLZ, Koenig JI, Lutty GA, Maric-Bilkan C, Stevens T, Tolunay HE, Koroshetz W. "Small Blood Vessels: Big Health Problems?": Scientific Recommendations of the National Institutes of Health Workshop. J Am Heart Assoc 2016; 5:JAHA.116.004389. [PMID: 27815267 PMCID: PMC5210346 DOI: 10.1161/jaha.116.004389] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Linfante I, Cipolla MJ. Improving Reperfusion Therapies in the Era of Mechanical Thrombectomy. Transl Stroke Res 2016; 7:294-302. [PMID: 27221511 PMCID: PMC4929023 DOI: 10.1007/s12975-016-0469-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 05/08/2016] [Accepted: 05/10/2016] [Indexed: 12/27/2022]
Abstract
Recent positive clinical trials using mechanical thrombectomy proved that endovascular recanalization is an effective treatment for patients with acute stroke secondary to large vessel occlusions. The trials offer definite evidence that in acute ischemia recanalization is a powerful predictor of good outcome. However, even in the era of rapid and effective recanalization using endovascular approaches, the percentage of patients with good outcomes varies between 33 and 71 %. In addition, the number of patients who are eligible for endovascular thrombectomy is small and usually based on having salvageable tissue on imaging. There is therefore room for improvement to both enhance the effectiveness of current practice and expand treatment to a larger subset of stroke patients. In this review, we highlight some of the most promising approaches to improve endovascular therapy by combining with strategies to enhance collateral perfusion and vascular protection.
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Johnson AC, Cipolla MJ. 34 Decreased dilation of hippocampal arterioles in a rat model of preeclampsia. Pregnancy Hypertens 2016. [DOI: 10.1016/j.preghy.2016.08.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ahnstedt H, Sweet J, Cruden P, Bishop N, Cipolla MJ. Effects of Early Post-Ischemic Reperfusion and tPA on Cerebrovascular Function and Nitrosative Stress in Female Rats. Transl Stroke Res 2016; 7:228-38. [PMID: 27125535 DOI: 10.1007/s12975-016-0468-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/11/2016] [Accepted: 04/19/2016] [Indexed: 01/13/2023]
Abstract
Stroke is a major health issue in women. Our previous studies in male rats showed decreased myogenic tone in middle cerebral arteries (MCAs) after ischemia and reperfusion (I/R), while tone in parenchymal arterioles (PAs) was increased. This vascular response may aggravate stroke damage in males by limiting reperfusion; however, the effect in females is not known. The current study investigated the effect of I/R and tissue plasminogen activator (tPA) on myogenic tone and reactivity of MCAs and PAs in female rats. Nitrosative stress by peroxynitrite and recruitment of inflammatory neutrophils to the microvasculature were also studied. Female rats were subjected to 2-h MCA filament occlusion (n = 16) or sham surgery (n = 17) and given tPA (1 mg/kg, i.v) or vehicle followed by 30-min reperfusion. Myogenic tone and reactivity were measured in isolated and pressurized MCAs and PAs from the same animals. Cerebrovascular F-actin, 3-nitrotyrosine (3-NT, peroxynitrite marker), and intravascular neutrophils were quantified. Myogenic tone and constriction to the nitric oxide synthase inhibitor Nω-nitro-L-arginine were decreased in MCAs but unchanged in PAs after I/R with no effect of tPA. F-actin and 3-NT expression were unaffected by I/R or tPA. Our study showed that MCAs from females, similar to what has been seen in males, are dilated after I/R and have decreased myogenic tone while tone in PAs was unchanged. Increased small vessel resistance may contribute to decreased reperfusion and worse outcome after stroke.
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