1
|
Hsu CK, Chang SJ, Lim LY, Chang HH, Shei-Dei Yang S. Methyl Palmitate Modulated NMDA-Induced Cerebral Hyperemia in Hypertensive Rats. J Vasc Res 2023; 60:137-147. [PMID: 37285812 DOI: 10.1159/000529916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 02/07/2023] [Indexed: 06/09/2023] Open
Abstract
N-methyl-D-aspartate (NMDA) receptors were found to be dysfunctional in hypertensive rats. Methyl palmitate (MP) has been shown to diminish the nicotine-induced increase in blood flow in the brainstem. The aim of this study was to determine how MP modulated NMDA-induced increased regional cerebral blood flow (rCBF) in normotensive (WKY), spontaneously hypertensive (SHR), and renovascular hypertensive (RHR) rats. The increase in rCBF after the topical application of experimental drugs was measured using laser Doppler flowmetry. Topical NMDA application induced an MK-801-sensitive increase in rCBF in anesthetized WKY rats, which was inhibited by MP pretreatments. This inhibition was prevented by pretreatment with chelerythrine (a PKC inhibitor). The NMDA-induced increase in rCBF was also inhibited by the PKC activator in a concentration-dependent manner. Neither MP nor MK-801 affected the increase in rCBF induced by the topical application of acetylcholine or sodium nitroprusside. Topical application of MP to the parietal cortex of SHRs, on the other hand, increased basal rCBF slightly but significantly. MP enhanced the NMDA-induced increase in rCBF in SHRs and RHRs. These results suggested that MP had a dual effect on the modulation of rCBF. MP appears to play a significant physiological role in CBF regulation.
Collapse
Affiliation(s)
- Chun-Kai Hsu
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, New Taipei, Taiwan
- School of Medicine, Tzu Chi University, Hualien, Taiwan
| | | | - Li-Yi Lim
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, New Taipei, Taiwan
- Department of Surgery, Hospital Canselor Tuanku Muhriz UKM, Kuala Lumpur, Malaysia
| | - Hsi-Hsien Chang
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, New Taipei, Taiwan
| | - Stephen Shei-Dei Yang
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, New Taipei, Taiwan
- School of Medicine, Tzu Chi University, Hualien, Taiwan
- Taipei Tzu Chi Hospital, Buddhist Medical Foundation, New Taipei, Taiwan
| |
Collapse
|
2
|
Li MW, Chao TC, Lim LY, Chang HH, Yang SSD. The Acute Effects and Mechanism of Ketamine on Nicotine-Induced Neurogenic Relaxation of the Corpus Cavernosum in Mice. Int J Mol Sci 2023; 24:ijms24086976. [PMID: 37108139 PMCID: PMC10138932 DOI: 10.3390/ijms24086976] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/30/2023] [Accepted: 04/04/2023] [Indexed: 04/29/2023] Open
Abstract
The present study aimed to investigate the acute effects and the mechanism of ketamine on nicotine-induced relaxation of the corpus cavernosum (CC) in mice. This study measured the intra-cavernosal pressure (ICP) of male C57BL/6 mice and the CC muscle activities using an organ bath wire myograph. Various drugs were used to investigate the mechanism of ketamine on nicotine-induced relaxation. Direct ketamine injection into the major pelvic ganglion (MPG) inhibited MPG-induced increases in ICP. D-serine/L-glutamate-induced relaxation of the CC was inhibited by MK-801 (N-methyl-D-aspartate (NMDA) receptor inhibitor), and nicotine-induced relaxation was enhanced by D-serine/L-glutamate. NMDA had no effect on CC relaxation. Nicotine-induced relaxation of the CC was suppressed by mecamylamine (a non-selective nicotinic acetylcholine receptor antagonist), lidocaine, guanethidine (an adrenergic neuronal blocker), Nw-nitro-L-arginine (a non-selective nitric oxide synthase inhibitor), MK-801, and ketamine. This relaxation was almost completely inhibited in CC strips pretreated with 6-hydroxydopamine (a neurotoxic synthetic organic compound). Ketamine inhibited cavernosal nerve neurotransmission via direct action on the ganglion and impaired nicotine-induced CC relaxation. The relaxation of the CC was dependent on the interaction of the sympathetic and parasympathetic nerves, which may be mediated by the NMDA receptor.
Collapse
Affiliation(s)
- Ming-Wei Li
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 23142, Taiwan
| | - Tze-Chen Chao
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 23142, Taiwan
| | - Li-Yi Lim
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 23142, Taiwan
| | - Hsi-Hsien Chang
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 23142, Taiwan
| | - Stephen Shei-Dei Yang
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei 23142, Taiwan
- School of Medicine, Tzu Chi University, Hualien 97004, Taiwan
| |
Collapse
|
3
|
Katz BM, Walton LR, Houston KM, Cerri DH, Shih YYI. Putative neurochemical and cell type contributions to hemodynamic activity in the rodent caudate putamen. J Cereb Blood Flow Metab 2023; 43:481-498. [PMID: 36448509 PMCID: PMC10063835 DOI: 10.1177/0271678x221142533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 09/28/2022] [Accepted: 10/21/2022] [Indexed: 12/02/2022]
Abstract
Functional magnetic resonance imaging (fMRI) is widely used by researchers to noninvasively monitor brain-wide activity. The traditional assumption of a uniform relationship between neuronal and hemodynamic activity throughout the brain has been increasingly challenged. This relationship is now believed to be impacted by heterogeneously distributed cell types and neurochemical signaling. To date, most cell-type- and neurotransmitter-specific influences on hemodynamics have been examined within the cortex and hippocampus of rodent models, where glutamatergic signaling is prominent. However, neurochemical influences on hemodynamics are relatively unknown in largely GABAergic brain regions such as the rodent caudate putamen (CPu). Given the extensive contribution of CPu function and dysfunction to behavior, and the increasing focus on this region in fMRI studies, improved understanding of CPu hemodynamics could have broad impacts. Here we discuss existing findings on neurochemical contributions to hemodynamics as they may relate to the CPu with special consideration for how these contributions could originate from various cell types and circuits. We hope this review can help inform the direction of future studies as well as interpretation of fMRI findings in the CPu.
Collapse
Affiliation(s)
- Brittany M Katz
- Neuroscience Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Lindsay R Walton
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kaiulani M Houston
- Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, New York University Grossman School of Medicine, New York, NY, USA
| | - Domenic H Cerri
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Yen-Yu Ian Shih
- Neuroscience Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Center for Animal MRI, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| |
Collapse
|
4
|
Chun-Kai H, Hsi-Hsien C, Shang-Jen C, Shei-Dei Stephen Y, Kuo-Feng H. Methyl palmitate modulates the nicotine-induced increase in basilar arterial blood flow. Microcirculation 2021; 28:e12686. [PMID: 33595915 DOI: 10.1111/micc.12686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 02/10/2021] [Indexed: 11/28/2022]
Abstract
Methyl palmitate (MP) is a fatty acid methyl ester. Our recent study indicated that adrenergic nerve-dependent functional sympathetic-sensory nerve interactions were abolished by MP in mesenteric arteries. However, the effect of MP on perivascular nerves and cerebral blood flow remains unclear. In this study, the increase in basilar arterial blood flow (BABF) after the topical application of nicotinic acetylcholine receptor agonists was measured using laser Doppler flowmetry in anesthetized rats. The choline (a selective α7-nicotinic acetylcholine receptor agonist)-induced increase in BABF was abolished by tetrodotoxin (a neurotoxin), NG -nitro-L-arginine (a nonselective NO synthase inhibitor), α-bungarotoxin (a selective α7-nicotinic acetylcholine receptor inhibitor), and chronic sympathetic denervation. In addition, the nicotine (a nicotinic acetylcholine receptor agonist)-induced increase in BABF was inhibited by MP in a concentration-dependent manner. The acetylcholine-induced increase in BABF was not affected by MP. The myography results revealed that nicotine-induced vasorelaxation was significantly inhibited by MP, but was reversed by chelerythrine (a protein kinase C inhibitor). MP-induced vasodilation was significantly greater in BA rings without endothelium compared to those with endothelium. Meanwhile, MP did not affect baseline BABF. Our results indicate that MP acts as a neuromodulator in the cerebral circulation where it activates the PKC pathway and causes a diminished nicotine-induced increase in blood flow in the brainstem, and that the vasorelaxation effect of MP may play a minor role.
Collapse
Affiliation(s)
- Hsu Chun-Kai
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, New Taipei, Taiwan
| | - Chang Hsi-Hsien
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, New Taipei, Taiwan
| | - Chang Shang-Jen
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, New Taipei, Taiwan.,School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Yang Shei-Dei Stephen
- Division of Urology, Department of Surgery, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, New Taipei, Taiwan.,School of Medicine, Tzu Chi University, Hualien, Taiwan.,Division of Neurosurgery, Department of Surgery, Taipei Tzu Chi Hospital, New Taipei, Taiwan
| | - Huang Kuo-Feng
- School of Medicine, Tzu Chi University, Hualien, Taiwan.,Division of Neurosurgery, Department of Surgery, Taipei Tzu Chi Hospital, New Taipei, Taiwan
| |
Collapse
|
5
|
Ansari MM, Ahmad A, Kumar A, Alam P, Khan TH, Jayamurugan G, Raza SS, Khan R. Aminocellulose-grafted-polycaprolactone coated gelatin nanoparticles alleviate inflammation in rheumatoid arthritis: A combinational therapeutic approach. Carbohydr Polym 2021; 258:117600. [PMID: 33593531 DOI: 10.1016/j.carbpol.2020.117600] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 12/25/2020] [Accepted: 12/29/2020] [Indexed: 12/20/2022]
Abstract
Rheumatoid arthritis (RA) is a chronic autoimmune disorder and serious cause of disability. Despite considerable advances in RA management, challenges like extensive drug metabolism and rapid clearance causes poor bioavailability. Core-shell nanocarriers for co-delivery of glycyrrhizic acid (GA) and budesonide against RA were developed. GA-loaded gelatin nanoparticles (NPs) were synthesized and coated with budesonide encapsulated aminocellulose-grafted polycaprolactone (PCL-AC). GA- and budesonide-loaded PCL-AC-gel NPs had diameter of 200-225 nm. Dual drug-loaded (DDL) NPs reduced joint swelling and erythema in rats while markedly ameliorating bone erosion evidenced by radiological analysis, suppressed collagen destruction, restored synovial tissue, bone and cartilage histoarchitecture with reduced inflammatory cells infiltration. NPs also reduced various inflammatory biomarkers such as TNF-α, IL-1β, COX-2, iNOS. Results of this study suggest that dual NPs exerted superior therapeutic effects in RA compared to free drugs which may be attributed to slow and sustained drug release and NPs' ability to inhibit inflammatory mediators.
Collapse
Affiliation(s)
- Md Meraj Ansari
- Institute of Nano Science and Technology, Habitat Centre, Phase 10, Sector 64, Mohali, Punjab, 160062, India
| | - Anas Ahmad
- Institute of Nano Science and Technology, Habitat Centre, Phase 10, Sector 64, Mohali, Punjab, 160062, India
| | - Ajay Kumar
- Institute of Nano Science and Technology, Habitat Centre, Phase 10, Sector 64, Mohali, Punjab, 160062, India
| | - Pravej Alam
- Department of Biology, College of Sciences and Humanities, Prince Sattam bin Abdulaziz University, PO Box - 173, Alkharj, 11942, Saudi Arabia
| | | | - Govindasamy Jayamurugan
- Institute of Nano Science and Technology, Habitat Centre, Phase 10, Sector 64, Mohali, Punjab, 160062, India
| | - Syed Shadab Raza
- Laboratory for Stem Cell & Restorative Neurology, Department of Biotechnology, Era's Lucknow Medical College and Hospital, Sarfarazganj, Lucknow, 226003, Uttar Pradesh, India; Department of Stem Cell Biology and Regenerative Medicine, Era University, Sarfarazganj, Lucknow, 226003, Uttar Pradesh, India
| | - Rehan Khan
- Institute of Nano Science and Technology, Habitat Centre, Phase 10, Sector 64, Mohali, Punjab, 160062, India.
| |
Collapse
|
6
|
Hydrogen Protons Modulate Perivascular Axo–axonal Interactions in the Middle Cerebral Artery of Rats. J Cardiovasc Pharmacol 2020; 76:112-121. [DOI: 10.1097/fjc.0000000000000838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
7
|
Lourenço CF, Ledo A, Barbosa RM, Laranjinha J. Neurovascular-neuroenergetic coupling axis in the brain: master regulation by nitric oxide and consequences in aging and neurodegeneration. Free Radic Biol Med 2017; 108:668-682. [PMID: 28435052 DOI: 10.1016/j.freeradbiomed.2017.04.026] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 02/21/2017] [Accepted: 04/18/2017] [Indexed: 02/08/2023]
Abstract
The strict energetic demands of the brain require that nutrient supply and usage be fine-tuned in accordance with the specific temporal and spatial patterns of ever-changing levels of neuronal activity. This is achieved by adjusting local cerebral blood flow (CBF) as a function of activity level - neurovascular coupling - and by changing how energy substrates are metabolized and shuttled amongst astrocytes and neurons - neuroenergetic coupling. Both activity-dependent increase of CBF and O2 and glucose utilization by active neural cells are inextricably linked, establishing a functional metabolic axis in the brain, the neurovascular-neuroenergetic coupling axis. This axis incorporates and links previously independent processes that need to be coordinated in the normal brain. We here review evidence supporting the role of neuronal-derived nitric oxide (•NO) as the master regulator of this axis. Nitric oxide is produced in tight association with glutamatergic activation and, diffusing several cell diameters, may interact with different molecular targets within each cell type. Hemeproteins such as soluble guanylate cyclase, cytochrome c oxidase and hemoglobin, with which •NO reacts at relatively fast rates, are but a few of the key in determinants of the regulatory role of •NO in the neurovascular-neuroenergetic coupling axis. Accordingly, critical literature supporting this concept is discussed. Moreover, in view of the controversy regarding the regulation of catabolism of different neural cells, we further discuss key aspects of the pathways through which •NO specifically up-regulates glycolysis in astrocytes, supporting lactate shuttling to neurons for oxidative breakdown. From a biomedical viewpoint, derailment of neurovascular-neuroenergetic axis is precociously linked to aberrant brain aging, cognitive impairment and neurodegeneration. Thus, we summarize current knowledge of how both neurovascular and neuroenergetic coupling are compromised in aging, traumatic brain injury, epilepsy and age-associated neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, suggesting that a shift in cellular redox balance may contribute to divert •NO bioactivity from regulation to dysfunction.
Collapse
Affiliation(s)
- Cátia F Lourenço
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal
| | - Ana Ledo
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal
| | - Rui M Barbosa
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - João Laranjinha
- Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.
| |
Collapse
|
8
|
Effect of cadmium chloride exposure during the induction of collagen induced arthritis. Chem Biol Interact 2015; 238:55-65. [PMID: 26070417 DOI: 10.1016/j.cbi.2015.06.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 05/31/2015] [Accepted: 06/02/2015] [Indexed: 12/16/2022]
Abstract
The precise cause of autoimmune diseases such as rheumatoid arthritis remains uncertain. Collagen induced arthritis (CIA) in animals is the most commonly used model of human rheumatoid arthritis (RA). Exposure of humans and animals to toxic metals is widespread. Cadmium is one of the most prevalent nephrotoxic heavy metal, but it may cause other systemic toxicity as well. Cadmium may cause adverse health effects by impairment of the immune systems and induction of reactive oxygen species. Since rheumatoid arthritis pathogenesis involve immune system disorder and chronic inflammation, the present study has been designed to find out the effect of cadmium chloride exposure on clinical manifestation of development of collagen induced rheumatoid arthritis. Arthritis was induced in rats by intradermal injection of emulsion of type II collagen in Complete Freund's Adjuvant. Rats were treated with cadmium chloride dissolved in drinking water at concentrations of 5ppm and 50ppm for 21 days from day of immunization. The effects of cadmium in the rats were assessed by biochemical parameters (articular elastase, articular nitrite, lipid peroxidation, reduced glutathione, catalase and superoxide dismutase) histopathological analysis and immunohistochemical expression of pro-inflammatory cytokines in rat joint tissue. Histopathological changes further confirmed the biochemical and immunohistochemical results. Our results suggest that exposure to cadmium chloride during the induction phase of collagen induced arthritis abrogate disease development at lower dose whereas exacerbates at higher dose in Wistar rats.
Collapse
|
9
|
Neha, Ansari MM, Khan HA. Deflazacort alleviate pro-inflammatory cytokines expression, oxidative stress and histopathological alterations in collagen induced arthritis in Wistar rats. INDIAN JOURNAL OF RHEUMATOLOGY 2014. [DOI: 10.1016/j.injr.2014.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
10
|
Warrillow SJ, Bellomo R. Preventing cerebral oedema in acute liver failure: the case for quadruple-H therapy. Anaesth Intensive Care 2014; 42:78-88. [PMID: 24471667 DOI: 10.1177/0310057x1404200114] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Severe cerebral oedema is a life-threatening complication of acute liver failure. Hyperammonaemia and cerebral hyperaemia are major contributing factors. A multimodal approach, which incorporates hyperventilation, haemodiafiltration, hypernatraemia and hypothermia (quadruple-H therapy), may prevent or attenuate severe cerebral oedema. This approach is readily administered by critical care clinicians and is likely to be more effective than the use of single therapies. Targeting of PaCO2 in the mild hyperventilation range, as seen in acute liver failure patients before intubation, aims to minimise hyperaemic cerebral oedema. Haemodiafiltration aims to achieve the rapid control of elevated blood ammonia concentrations by its removal and to reduce production via the lowering of core temperature. The administration of concentrated saline increases serum tonicity and further reduces cerebral swelling. In addition, the pathologically increased cerebral blood-flow is further attenuated by therapeutic hypothermia. The combination of all four treatments in a multimodal approach may be a safe and effective means of attenuating or treating the cerebral oedema of acute liver failure and preventing death from neurological complications.
Collapse
Affiliation(s)
- S J Warrillow
- Department of Intensive Care, Austin Health, Victoria, Australia
| | | |
Collapse
|
11
|
Institoris A, Lenti L, Domoki F, Wappler E, Gáspár T, Katakam PV, Bari F, Busija DW. Cerebral microcirculatory responses of insulin-resistant rats are preserved to physiological and pharmacological stimuli. Microcirculation 2013; 19:749-56. [PMID: 22845548 DOI: 10.1111/j.1549-8719.2012.00213.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 07/23/2012] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Previously, we have shown that IR impairs the vascular reactivity of the major cerebral arteries of ZO rats prior to the occurrence of Type-II diabetes mellitus. However, the functional state of the microcirculation in the cerebral cortex is still being explored. METHODS We tested the local CoBF responses of 11-13-week-old ZO (n = 31) and control ZL (n = 32) rats to several stimuli measured by LDF using a closed cranial window setup. RESULTS The topical application of 1-100 μm bradykinin elicited the same degree of CoBF elevation in both ZL and ZO groups. There was no significant difference in the incidence, latency, and amplitude of the NMDA-induced CSD-related hyperemia between the ZO and ZL groups. Hypercapnic CoBF response to 5% carbon-dioxide ventilation did not significantly change in the ZO compared with the ZL. Topical bicuculline-induced cortical seizure was accompanied by the same increase of CoBF in both the ZO and ZL at all bicuculline doses. CONCLUSIONS CoBF responses of the microcirculation are preserved in the early period of the metabolic syndrome, which creates an opportunity for intervention to prevent and restore the function of the major cerebral vascular beds.
Collapse
Affiliation(s)
- Adam Institoris
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA.
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Chang HH, Lee YC, Chen MF, Kuo JS, Lee TJF. Sympathetic activation increases basilar arterial blood flow in normotensive but not hypertensive rats. Am J Physiol Heart Circ Physiol 2012; 302:H1123-30. [DOI: 10.1152/ajpheart.01016.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The close apposition between sympathetic and parasympathetic nerve terminals in the adventitia of cerebral arteries provides morphological evidence that sympathetic nerve activation causes parasympathetic nitrergic vasodilation via a sympathetic-parasympathetic interaction mechanism. The decreased parasympathetic nerve terminals in basilar arteries (BA) of spontaneously hypertensive rat (SHR) and renovascular hypertensive rats (RHR) compared with Wistar-Kyoto rats (WKY), therefore, would diminish this axo-axonal interaction-mediated neurogenic vasodilation in hypertension. Increased basilar arterial blood flow (BABF) via axo-axonal interaction during sympathetic activation was, therefore, examined in anesthetized rats by laser-Doppler flowmetry. Electrical stimulation (ES) of sympathetic nerves originating in superior cervical ganglion (SCG) and topical nicotine (10–30 μM) onto BA of WKY significantly increased BABF. Both increases were inhibited by tetrodotoxin, 7-nitroindazole (neuronal nitric oxide synthase inhibitor), and ICI-118,551 (β2-adrenoceptor antagonist), but not by atenolol (β1-adrenoceptor antagonist). Topical norepinephrine onto BA also increased BABF, which was abolished by atenolol combined with 7-nitroindazole or ICI-118,551. Similar results were found in prehypertensive SHR. However, in adult SHR and RHR, ES of sympathetic nerves or topical nicotine caused minimum or no increase of BABF. It is concluded that excitation of sympathetic nerves to BA in WKY causes parasympathetic nitrergic vasodilation with increased BABF. This finding indicates an endowed functional neurogenic mechanism for increasing the BABF or brain stem blood flow in coping with increased local sympathetic activities in acutely stressful situations such as the “fight-or-flight response.” This increased blood flow in defensive mechanism diminishes in genetic and nongenetic hypertensive rats due most likely to decreased parasympathetic nitrergic nerve terminals.
Collapse
Affiliation(s)
- Hsi-Hsien Chang
- Institute of Medical Sciences, College of Medicine,
- Department of Life Sciences, and
- Center for Vascular Medicine, College of Life Sciences, Tzu Chi University, Hualien, Taiwan
| | - Yuan-Chieh Lee
- Center for Vascular Medicine, College of Life Sciences, Tzu Chi University, Hualien, Taiwan
- Departments of 4Ophthalmology and
| | - Mei-Fang Chen
- Center for Vascular Medicine, College of Life Sciences, Tzu Chi University, Hualien, Taiwan
- Research, Buddhist Tzu Chi General Hospital, Hualien, Taiwan; and
| | - Jon-Son Kuo
- Institute of Medical Sciences, College of Medicine,
- Center for Vascular Medicine, College of Life Sciences, Tzu Chi University, Hualien, Taiwan
| | - Tony J. F. Lee
- Institute of Medical Sciences, College of Medicine,
- Department of Life Sciences, and
- Center for Vascular Medicine, College of Life Sciences, Tzu Chi University, Hualien, Taiwan
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois
| |
Collapse
|
13
|
Lee TJF, Chang HH, Lee HC, Chen PY, Lee YC, Kuo JS, Chen MF. Axo-axonal interaction in autonomic regulation of the cerebral circulation. Acta Physiol (Oxf) 2011; 203:25-35. [PMID: 21159131 DOI: 10.1111/j.1748-1716.2010.02231.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Noradrenaline (NE) and acetylcholine (ACh) released from the sympathetic and parasympathetic neurones in cerebral blood vessels were suggested initially to be the respective vasoconstricting and dilating transmitters. Both substances, however, are extremely weak post-synaptic transmitters. Compelling evidence indicates that nitric oxide (NO) which is co-released with ACh from same parasympathetic nerves is the major transmitter for cerebral vasodilation, and its release is inhibited by ACh. NE released from the sympathetic nerve, acting on presynaptic β2-adrenoceptors located on the neighbouring parasympathetic nitrergic nerves, however, facilitates NO release with enhanced vasodilation. This axo-axonal interaction mediating NE transmission is supported by close apposition between sympathetic and parasympathetic nerve terminals, and has been shown in vivo at the base of the brain and the cortical cerebral circulation. This result reveals the physiological need for increased regional cerebral blood flow in 'fight-or-flight response' during acute stress. Furthermore, α7- and α3β2-nicotinic ACh receptors (nAChRs) on sympathetic nerve terminals mediate release of NE, leading to cerebral nitrergic vasodilation. α7-nAChR-mediated but not α3β2-nAChR-mediated cerebral nitrergic vasodilation is blocked by β-amyloid peptides (Aβs). This may provide an explanation for cerebral hypoperfusion seen in patients with Alzheimer's disease. α7- and α3β2-nAChR-mediated nitrergic vasodilation is blocked by cholinesterase inhibitors (ChEIs) which are widely used for treating Alzheimer's disease, leading to possible cerebral hypoperfusion. This may contribute to the limitation of clinical use of ChEIs. ChEI blockade of nAChR-mediated dilation like that by Aβs is prevented by statins pretreatment, suggesting that efficacy of ChEIs may be improved by concurrent use of statins.
Collapse
Affiliation(s)
- T J F Lee
- College of Life Sciences, Institute of Life Science, Tzu Chi University, Hualien, Taiwan.
| | | | | | | | | | | | | |
Collapse
|
14
|
Lenti L, Domoki F, Gáspár T, Snipes JA, Bari F, Busija DW. N-methyl-D-aspartate induces cortical hyperemia through cortical spreading depression-dependent and -independent mechanisms in rats. Microcirculation 2011; 16:629-39. [PMID: 19657965 DOI: 10.1080/10739680903131510] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE N-methyl-d-aspartate (NMDA) is a powerful cerebrovascular dilator in vivo. Cortical spreading depression (CSD) has recently been shown to contribute to the pial arteriolar dilation in mice. Our main aim was to examine the participation of CSD in the overall cerebrovascular response to NMDA in the rat. METHODS Anesthetized Wistar rats (eight weeks old) were equipped with a closed cranial window to allow topical application of NMDA (10(-5)-10(-3) M) to the parietal cortex. Cortical blood flow (CoBF) under and outside the cranial window was simultaneously monitored by using a two-channel laser-Doppler flowmeter. CSDs were detected by recording the changes in the cortical DC potential. RESULTS Concentrations of 10(-4) and 10(-3) M of NMDA evoked single CSDs associated with rapid, transient hyperemia, followed by a sustained, but reduced, increase in CoBF. The latency and magnitude of the CoBF responses were dose dependent. The higher dose resulted in shorter latency (100+/-5* vs. 146+/-11 seconds, *P<0.05; mean+/-standard error of the mean) and larger overall flow response (77+/-12* vs. 28+/-3% from baseline) under, but not outside, the cranial window. CONCLUSIONS NMDA elicits dose-dependent increases in CoBF that are composed of CSD-dependent and -independent components in rats.
Collapse
Affiliation(s)
- Laura Lenti
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA.
| | | | | | | | | | | |
Collapse
|
15
|
Ances BM, Greenberg JH, Detre JA. Interaction between nitric oxide synthase inhibitor induced oscillations and the activation flow coupling response. Brain Res 2009; 1309:19-28. [PMID: 19900416 DOI: 10.1016/j.brainres.2009.09.119] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Revised: 09/16/2009] [Accepted: 09/16/2009] [Indexed: 02/03/2023]
Abstract
The role of nitric oxide (NO) in the activation-flow coupling (AFC) response to periodic electrical forepaw stimulation was investigated using signal averaged laser Doppler (LD) flowmetry. LD measures of calculated cerebral blood flow (CBF) were obtained both prior and after intra-peritoneal administration of the non-selective nitric oxide synthase (NOS) inhibitor, N(G)-nitro-L-arginine (L-NNA) (40 mg/kg). Characteristic baseline low frequency vasomotion oscillations (0.17 Hz) were observed after L-NNA administration. These LD(CBF) oscillations were synchronous within but not between hemispheres. L-NNA reduced the magnitude of the AFC response (p<0.05) for longer stimuli (1 min) with longer inter-stimulus intervals (2 min). In contrast, the magnitude of the AFC response for short duration stimuli (4 s) with short inter-stimulus intervals (20 s) was augmented (p<0.05) after L-NNA. An interaction occurred between L-NNA induced vasomotion oscillations and the AFC response with the greatest increase occurring at the stimulus harmonic closest to the oscillatory frequency. Nitric oxide may therefore modulate the effects of other vasodilators involved in vasomotion oscillations and the AFC response.
Collapse
Affiliation(s)
- Beau M Ances
- Department of Neurology, Washington University in St. Louis, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
| | | | | |
Collapse
|
16
|
Busija DW, Bari F, Domoki F, Louis T. Mechanisms involved in the cerebrovascular dilator effects of N-methyl-d-aspartate in cerebral cortex. ACTA ACUST UNITED AC 2007; 56:89-100. [PMID: 17716743 PMCID: PMC2174154 DOI: 10.1016/j.brainresrev.2007.05.011] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 05/10/2007] [Accepted: 05/21/2007] [Indexed: 12/13/2022]
Abstract
Glutamate and its synthetic analogues N-methyl-d-aspartate (NMDA), kainate, and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) are potent dilator agents in the cerebral circulation. The close linkage between neural activity-based release and actions of glutamate on neurons and the related decrease in cerebral vascular resistance is a classic example in support of the concept of tight coupling between increased neural activity and cerebral blood flow. However, mechanisms involved in promoting cerebral vasodilator responses to glutamatergic agents are controversial. Here we review the development and current status of this important field of research especially in respect to cerebrovascular responses to NMDA receptor activation.
Collapse
Affiliation(s)
- David W Busija
- Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157-1010, USA.
| | | | | | | |
Collapse
|
17
|
Raghavan M, Marik PE. Therapy of intracranial hypertension in patients with fulminant hepatic failure. Neurocrit Care 2006; 4:179-89. [PMID: 16627910 DOI: 10.1385/ncc:4:2:179] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 12/19/2022]
Abstract
Severe intracranial hypertension (IH) in the setting of fulminant hepatic failure (FHF) carries a high mortality and is a challenging disease for the critical care provider. Despite considerable improvements in the understanding of the pathophysiology of cerebral edema during liver failure, therapeutic maneuvers that are currently available to treat this disease are limited. Orthotopic liver transplantation is currently the only definitive therapeutic strategy that improves outcomes in patients with FHF. However, many patients die prior to the availability of donor organs, often because of cerebral herniation. Currently, two important theories prevail in the understanding of the pathophysiology of IH during FHF. Ammonia and glutamine causes cytotoxic cerebral injury while cerebral vasodilation caused by loss of autoregulation increases intracranial pressure (ICP) and predisposes to herniation. Although ammonia-reducing strategies are limited in humans, modulation of cerebral blood flow seems promising, at least during the early stages of hepatic encephalopathy. ICP monitoring, transcranial Doppler, and jugular venous oximetry offer valuable information regarding intracranial dynamics. Induced hypothermia, hypertonic saline, propofol sedation, and indomethacin are some of the newer therapies that have been shown to improve survival in patients with severe IH. In this article, we review the pathophysiology of IH in patients with FHF and outline various therapeutic strategies currently available in managing these patients in the critical care setting.
Collapse
Affiliation(s)
- Murugan Raghavan
- Liver Transplant ICU, Department of Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | | |
Collapse
|
18
|
Pupi A, Nobili FM. PET is better than perfusion SPECT for early diagnosis of Alzheimer's disease -- against. Eur J Nucl Med Mol Imaging 2006; 32:1466-72. [PMID: 16283180 DOI: 10.1007/s00259-005-1937-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Alberto Pupi
- Clinical Pathophysiology Department, University of Florence, Italy.
| | | |
Collapse
|
19
|
Domoki F, Perciaccante JV, Shimizu K, Puskar M, Busija DW, Bari F. N-methyl-D-aspartate-induced vasodilation is mediated by endothelium-independent nitric oxide release in piglets. Am J Physiol Heart Circ Physiol 2002; 282:H1404-9. [PMID: 11893577 DOI: 10.1152/ajpheart.00523.2001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
N-methyl-D-aspartate (NMDA) elicits pial arteriolar dilation that has been associated with neuronal nitric oxide (NO) production. However, endothelial factors or glial P-450 epoxygenase products may play a role. We tested whether NMDA-induced pial vasodilation 1) primarily involves NO diffusion from the parenchyma to the surface arterioles, 2) involves intact endothelial function, and 3) involves a miconazole-sensitive component. Arteriolar diameters were determined using closed cranial window-intravital microscopy in anesthetized piglets. NMDA (10-100 microM) elicited virtually identical dose-dependent dilations in paired arterioles (r = 0.94, n = 15). However, NMDA- but not bradykinin (BK)-induced dilations of arteriolar sections over large veins were reduced by 31 +/- 1% (means +/- SE, P < 0.05, n = 4) compared with adjacent sections on the cortical surface. Also, 100 microM NMDA increased cerebrospinal fluid levels of NO metabolites from 3.7 +/- 1.0 to 5.3 +/- 1.2 microM (P < 0.05, n = 6). Endothelial stunning by intracarotid injection of phorbol 12,13-dibutyrate did not affect NMDA-induced vasodilation but attenuated vascular responses to hypercapnia and BK by approximately 70% (n = 7). Finally, miconazole (n = 6, 20 microM) pretreatment and coapplication with NMDA did not alter vascular responses to NMDA. In conclusion, NMDA appears to dilate pial arterioles exclusively through release and diffusion of NO from neurons to the pial surface in piglets.
Collapse
Affiliation(s)
- Ferenc Domoki
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston Salem, North Carolina 27157-1010, USA.
| | | | | | | | | | | |
Collapse
|
20
|
Abstract
Hepatic encephalopathy (HE) results from acute or chronic liver dysfunction and is associated with hyperammonemia. Ammonium ions penetrate from blood to brain, where they form glutamine (Gln) in the reaction with glutamate catalyzed by an astroglia-specific enzyme, glutamine synthetase (GS). Experimental data suggest that many manifestations of HE can be ascribed to increased Gln synthesis and accumulation in the brain. In HE resulting from acute liver failure ("fulminant hepatic failure"), the osmotic action of Gln appears to be in a large degree responsible for cerebral edema and edema-associated disturbances of cerebral blood flow and ionic homeostasis. In chronic HE not accompanied by cerebral edema, Gln contributes to impairment of cerebral energy metabolism, and its increased transport from brain to the periphery accelerates the blood-to-brain transport of aromatic amino acids, of which tryptophen (Trp) is converted to metabolites directly implicated in HE. Most of the evidence that Gln participates in pathological events has been derived from their disappearance or amelioration in HE rats in which the cerebral Gln content was reduced by treatment with a GS inhibitor, methionine sulfoximine.
Collapse
Affiliation(s)
- J Albrecht
- Department of Neurotoxicology, Medical Research Center, Polish Academy of Sciences, Warsaw, Poland.
| | | |
Collapse
|
21
|
Benyó Z, Lacza Z, Hortobágyi T, Görlach C, Wahl M. Functional importance of neuronal nitric oxide synthase in the endothelium of rat basilar arteries. Brain Res 2000; 877:79-84. [PMID: 10980246 DOI: 10.1016/s0006-8993(00)02611-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The function of the neuronal isoform of nitric oxide synthase (nNOS) was studied by comparing the effects of the specific nNOS blocker 7-nitro indazole monosodium salt (7-NINA) with that of the general NOS inhibitor N(G)-nitro-L-arginine (L-NA) in isolated rat basilar arteries (BAs). 7-NINA had no significant effect on the resting tone of the vessels, while both L-NA and 1H-[1,2,4]oxadiazolo[4, 3-a]quinoxalin-1-one (ODQ), a selective inhibitor of the soluble guanylyl cyclase, induced contraction. The relaxant effect of bradykinin was attenuated in the presence of L-NA but was not changed by 7-NINA. In contrast, 7-NINA markedly reduced the acetylcholine-induced, endothelium-dependent relaxation. These results demonstrate that nNOS contributes significantly to the relaxant effect of acetylcholine, indicating the functional importance of this isoenzyme in the cerebrovascular endothelium.
Collapse
Affiliation(s)
- Z Benyó
- Department of Physiology, Ludwig-Maximilians University, Munich, Germany.
| | | | | | | | | |
Collapse
|
22
|
Nakai M, Maeda M. Cerebral cortical muscarinic cholinergic and N-methyl-D-aspartate receptors mediate increase in cortical blood flow elicited by chemical stimulation of periaqueductal gray matter. Neuroscience 2000; 98:449-57. [PMID: 10869839 DOI: 10.1016/s0306-4522(00)00105-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The periaqueductal gray matter is implicated in the central processing of defensive reactions. We found previously that, when stimulated by N-methyl-D-aspartate, the caudal third of its lateral subdivision elicited an increase in blood flow over widespread cerebral neocortical areas and that a major proportion of the flow increase was inhibited by topical cortical application of scopolamine, an antagonist of muscarinic receptors. The present study was undertaken to elucidate the roles of cortical nicotinic and excitatory amino acid receptors in the mediation of the flow increase in 66 anaesthetized, cervically cordotomized, artificially ventilated rats with open cranial windows. We found that the flow increase (laser-Doppler flowmetry) was resistant to antagonists of non-N-methyl-D-aspartate receptors and of nicotinic receptors. The response was, however, attenuated to a substantial extent by topical and intravenous N-methyl-D-aspartate receptor antagonists, MK-801 and topical D(-)-2-amino-5-phosphonopentanoic acid. Combined topical application of the latter antagonist with scopolamine attenuated the flow increase to a further extent beyond that achieved with either of the antagonists alone. Topical applications of acetylcholine and N-methyl-D-aspartate individually increased the cortical blood flow. A modest synergism was observed between the actions of these two agonists.Overall, we suggest that in the face of stimuli which provoke defensive reactions, the periaqueductal gray matter may elicit an increase in cortical blood flow by utilizing the cortical acetylcholine-muscarinic receptor system and the cortical excitatory amino acid-N-methyl-D-aspartate receptor system. The vasomotor actions of these two transmitter-receptor systems may operate independently of each other as well as in harmony with each other.
Collapse
Affiliation(s)
- M Nakai
- National Cardiovascular Center Research Institute, 565-8565, Osaka, Japan
| | | |
Collapse
|
23
|
Hudetz AG, Wood JD, Kampine JP. 7-Nitroindazole impedes erythrocyte flow response to isovolemic hemodilution in the cerebral capillary circulation. J Cereb Blood Flow Metab 2000; 20:220-4. [PMID: 10698058 DOI: 10.1097/00004647-200002000-00002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The role of nitric oxide (NO) in the mechanism of hemodilution-induced cerebral hyperemia is unclear. Based on findings in hypoxemia, the authors hypothesize that NO of neuronal origin contributes to an increase in velocity of erythrocytes in the cerebral microcirculation during anemia produced by isovolemic hemodilution. The change in erythrocyte velocity in cerebrocortical capillaries was assessed by intravital fluorescence video microscopy. A closed cranial window was implanted over the frontoparietal cortex of barbiturate-anesthetized, ventilated adult rats. Erythrocytes were labeled in vitro with fluorescein isothiocyanate and infused intravenously, and their velocity in subsurface capillaries was measured by frame-to-frame image tracking. Arterial blood was withdrawn in increments of 2 mL and replaced by serum albumin; arterial blood pressure was maintained at control level with an infusion of methoxamine. Erythrocyte velocity increased progressively, reaching 215% of baseline, as arterial hematocrit was reduced from 45% to 17%. Pretreatment of a separate group of rats with 7-nitroindazole (20 mg/kg intraperitoneally), a relatively selective inhibitor of neuronal NO synthase, abolished the increase in velocity at hematocrits greater than 20%, but the maximum velocity attained at the lowest hematocrit was similar to that in the control group. The results suggest that NO from neuronal source may contribute to the increase in capillary erythrocyte flow during moderate isovolemic hemodilution.
Collapse
Affiliation(s)
- A G Hudetz
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee 53226, USA
| | | | | |
Collapse
|
24
|
Fillenz M, Lowry JP, Boutelle MG, Fray AE. The role of astrocytes and noradrenaline in neuronal glucose metabolism. ACTA PHYSIOLOGICA SCANDINAVICA 1999; 167:275-84. [PMID: 10632627 DOI: 10.1046/j.1365-201x.1999.00578.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the classical model the energy requirements during neuronal activation are provided by the delivery of additional glucose directly into the extracellular compartment that results from the increase in local cerebral blood flow (rCBF). The present review proposes that astrocytes play a key role in the response to neuronal activation. Arginine for the synthesis of NO, which has a major role in the increase in rCBF, is released from astrocytes in response to stimulation of astrocytic glutamate receptors. The increased delivery of glucose by the blood stream enters astrocytes, where some of it is converted to glycogen. During neuronal activation there is a decrease in extracellular glucose owing to increased utilization followed by a delayed increase; this results from stimulation of astrocytic beta-adrenergic receptors, which leads to a breakdown of glycogen and the export of glucose.
Collapse
Affiliation(s)
- M Fillenz
- University Laboratory of Physiology, Parks Road, Oxford, UK
| | | | | | | |
Collapse
|
25
|
Ochiai-Kanai R, Hasegawa K, Takeuchi Y, Yoshioka H, Sawada T. Immunohistochemical nitrotyrosine distribution in neonatal rat cerebrocortical slices during and after hypoxia. Brain Res 1999; 847:59-70. [PMID: 10564736 DOI: 10.1016/s0006-8993(99)02020-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The peroxynitrite contributions to hypoxic damage in brain slices that arise from N-methyl-D-aspartate (NMDA) receptor activation were studied by following the temporal-spatial course of nitrotyrosine (NT) formation during six conditions: hypoxia (pO(2)<5 mmHg) with or without 10 microM MK-801 treatment; with exposure to 10, 100 and 1000 microM NMDA; and no treatment (control). In each experiment, twenty 350-micrometer thick cerebrocortical slices, obtained from the parietal lobes of ten 7-day-old Sprague-Dawley rats, were metabolically recovered and allowed to respire in a well-oxygenated perfusion system. Thirty minutes exposures to hypoxia or NMDA were followed by 2 h of oxygenated reperfusion. MK-801 administration began 15 min prior to hypoxia and was discontinued during reperfusion. Anti-NT serum immunohistochemistry stains in 20-micrometer frozen sections of slices taken during oxygenated reperfusion, after hypoxia or NMDA exposure, were positive in both neurons and endothelial cells. NT-positive neurons were detected sooner after hypoxia than after NMDA exposure, suggesting that mechanisms of superoxide generation were different in both groups. After hypoxia and even more so after NMDA exposure, more intense NT-positive staining was observed in endothelial cells than in neurons. Cell damage after hypoxia was attenuated by MK-801. MK-801 decreased post-hypoxia counts of NT-stained endothelial cells by 78.5% (p<0. 001) and NT-stained neurons by 54.1% (p<0.05). Our findings suggest that NMDA receptor activation in hypoxic brain slices is associated with increased post-hypoxic peroxynitrite production that contributes to acute neuronal death and endothelial cell injury. Peroxynitrite injury to endothelial cells, caused either by increased peroxynitrite from within or from increased vulnerability to peroxynitrite from without, might play an important role in hypoxic-ischemic brain injury and NMDA-induced brain injury.
Collapse
Affiliation(s)
- R Ochiai-Kanai
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kajiicho, Kyoto, Japan.
| | | | | | | | | |
Collapse
|
26
|
Affiliation(s)
- A T Blei
- Department of Medicine, VA Lakeside Medical Center, Northwestern University, Chicago 60611, USA
| | | |
Collapse
|
27
|
Master S, Gottstein J, Blei AT. Cerebral blood flow and the development of ammonia-induced brain edema in rats after portacaval anastomosis. Hepatology 1999; 30:876-80. [PMID: 10498637 DOI: 10.1002/hep.510300428] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Two mechanisms may account for brain edema in fulminant hepatic failure: the osmotic effects of brain glutamine, a product of ammonia detoxification, and a change of cerebral blood flow (CBF). We have shown brain edema, a marked increase in brain glutamine, and a selective rise in CBF in rats after portacaval anastomosis receiving an ammonia infusion. In this study, we inhibited the activity of glutamine synthetase with methionine-sulfoximine (MSO) and examined ammonia levels, brain water and CBF. Four groups received either a continuous ammonium acetate or control infusion; half of the animals had been pretreated with MSO or vehicle. The ammonia group exhibited brain edema (79.97 +/- 0.04 vs. 81.11 +/- 0. 13% water), an increase in cerebrospinal fluid (CSF) glutamine (1.29 +/- 0.21 vs. 2.84 +/- 0.39 mmol/L) and CBF (63 +/- 11 vs. 266 +/- 45 mL/min/100 g brain). When MSO was added to the ammonia infusion, ammonia levels rose further (928 +/- 51 vs. 1,293 +/- 145 mmol/L, P <.05) but CSF glutamine decreased (2.84 +/- 0.39 vs. 1.61 +/- 0.2 mmol/L, P <.01). Brain edema (80.48 +/- 0.11%) and cerebral hyperemia (140 +/- 25 mL/min/100 g brain) were significantly ameliorated in the ammonia plus MSO group. Brain output of circulating nitric oxide (NO(x)) was increased in the ammonia-infused group but normalized in the ammonia plus MSO group. In this model, the rise of CBF reflects intracranial events that occur after glutamine synthesis. Activation of nitric oxide synthase in the brain could account for these findings.
Collapse
Affiliation(s)
- S Master
- Department of Medicine, Lakeside VAMC and Northwestern University, Chicago, IL, USA
| | | | | |
Collapse
|
28
|
Faraci FM, Sobey CG. Role of soluble guanylate cyclase in dilator responses of the cerebral microcirculation. Brain Res 1999; 821:368-73. [PMID: 10064823 DOI: 10.1016/s0006-8993(99)01110-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Responses of cerebral blood vessels to nitric oxide (NO) are mediated by soluble guanylate cyclase (sGC)-dependent and potentially by sGC-independent mechanisms. One sGC-independent mechanism by which NO may produce vasodilatation is inhibition of formation of a vasoconstrictor metabolite produced through the cytochrome P450 pathway. In these experiments, we examined the hypothesis that dilatation of cerebral microvessels in response to NO is dependent on activation of sGC. Diameters of cerebral arterioles (baseline diameter=94+/-5 micrometers, mean+/-S.E.) were measured using a closed cranial window in anesthetized rabbits. Under control conditions, YC-1 [3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole], an NO-independent activator of sGC, produced vasodilation that was blocked by ODQ (1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one)(10 microM), an inhibitor of sGC. These findings indicate that sGC is functionally important in cerebral arterioles. In addition, acetylcholine (which stimulates endogenous production of NO by endothelium) produced dilatation of cerebral arterioles that was inhibited by ODQ. For example, 1 microM acetylcholine dilated cerebral arterioles by 34+/-7 and 5+/-1% in the absence and presence of ODQ (10 microM), respectively. Increases in arteriolar diameter in response to sodium nitroprusside (1 microM, an NO donor) were inhibited by approximately 80% by ODQ, but were not affected by 17-ODYA (10 microM) or clotrimazole (10 microM), inhibitors of the cytochrome P450 pathway. Thus, dilatation of the cerebral microcirculation in response to exogenously applied and endogenously produced NO is dependent, in large part, on activation of sGC.
Collapse
Affiliation(s)
- F M Faraci
- Department of Internal Medicine, Cardiovascular Center, University of Iowa College of Medicine, Iowa City, IA 52242, USA
| | | |
Collapse
|
29
|
Affiliation(s)
- F M Faraci
- Department of Internal Medicine, Cardiovascular Center, University of Iowa College of Medicine, Iowa City 52242, USA
| | | |
Collapse
|