Search results for: Tsutomu Nakahara

Items from 1 to 20 out of 76 results

article

Pharmacological depletion of retinal neurons prevents vertical angiogenic sprouting without affecting the superficial vascular plexus

Akane Morita, Mika Yoshizumi, Shiho Arima, Asami Mori, more

Developmental Dynamics > 250 > 4 > 497 - 512

Background In mice, a tri‐layered (superficial, intermediate, and deep) vascular structure is formed in the retina during the third postnatal week. Short‐term treatment of newborn mice with vascular endothelial growth factor (VEGF) receptor inhibitors delays the formation of superficial vascular plexus and this allows us to investigate the developmental process of superficial and deep vascular plexuses...

article

Transient phenotypic changes in endothelial cells and pericytes in neonatal mouse retina following short‐term blockade of vascular endothelial growth factor receptors

Akane Morita, Asami Mori, Shiho Arima, Kenji Sakamoto, more

Developmental Dynamics > 247 > 5 > 699 - 711

Background: A short‐term interruption of vascular development causes structural abnormalities in retinal vasculature. However, the detailed changes in vascular components (endothelial cells, pericytes, and basement membranes) remain to be fully determined. The present study aimed to provide a detailed description of morphological changes in vascular components following a short‐term interruption of...

article

l-Citrulline improves cerebral blood flow in migraine model rats

Yuki Kurauchi, Koichi Mokudai, Masahiko Morita, Ayako Kamimura, more

Journal of Functional Foods > 2017 > 38 > PA > 540-544

We have previously reported that intravenous injection of l-citrulline, an α-amino acid isolated from watermelon juice, prevented the decrease in cerebral blood flow (CBF) during cortical spreading depression (CSD) in rats, a widely accepted animal model of migraine aura. However it is not clear whether oral l-citrulline administration improves CBF during CSD or not. For clinical application of l-citrulline...

article

Opioid receptor activation is involved in neuroprotection induced by TRPV1 channel activation against excitotoxicity in the rat retina

Kenji Sakamoto, Taiyo Kuroki, Tomonori Sagawa, Hiroko Ito, more

European Journal of Pharmacology > 2017 > 812 > C > 57-63

Recently, we reported that capsaicin, a transient receptor potential vanilloid type1 (TRPV1) agonist, protected against excitotoxicity induced by intravitreal N-methyl-D-aspartic acid (NMDA) in the rats in vivo. It has been reported that morphine, an opioid receptor agonist, ameliorated excitotoxicity induced by ischemia-reperfusion in the retina, and that capsaicin-induced neuroprotection was reduced...

article

Probucol prevents the attenuation of β₂-adrenoceptor-mediated vasodilation of retinal arterioles in diabetic rats

Asami Mori, Kentaro Higashi, Shun Wakao, Kenji Sakamoto, more

Naunyn-Schmiedeberg's Archives of Pharmacology > 2017 > 390 > 12 > 1247-1253

Probucol is an antihyperlipidemic drug with potent antioxidant properties. Oxidative stress plays an important role in the pathogenesis of diabetic retinopathy. In this study, we aimed to investigate the protective effects of probucol against diabetes-induced retinal vascular dysfunction in a rat model of diabetes. Diabetes was induced by a combination of streptozotocin treatment and D-glucose feeding,...

article

MEK/ERK- and calcineurin/NFAT-mediated mechanism of cerebral hyperemia and brain injury following NMDA receptor activation

Yuki Kurauchi, Rintaro Kinoshita, Asami Mori, Kenji Sakamoto, more

Biochemical and Biophysical Research Communications > 2017 > 488 > 2 > 329-334

N-methyl-d-aspartate (NMDA) receptor activation increases regional cerebral blood flow (rCBF) and induces neuronal injury, but similarities between these processes are poorly understood. In this study, by measuring rCBF in vivo, we identified a clear correlation between cerebral hyperemia and brain injury. NMDA receptor activation induced brain injury as a result of rCBF increase, which was attenuated...

article

Stimulation of μ-opioid receptors dilates retinal arterioles by neuronal nitric oxide synthase-derived nitric oxide in rats

Eriko Someya, Asami Mori, Kenji Sakamoto, Kunio Ishii, more

European Journal of Pharmacology > 2017 > 803 > C > 124-129

Opioids contribute to the regulation of cerebral vascular tone. The purpose of this study was to examine the effects of herkinorin, a non-opioid μ-opioid receptor agonist derived from salvinorin A, on blood vessels in the rat retina and to investigate the mechanism underlying the herkinorin-induced retinal vasodilatory response. Ocular fundus images were captured using an original high-resolution...

article

Anti-diabetic drug metformin dilates retinal blood vessels through activation of AMP-activated protein kinase in rats

Asami Mori, Eriko Ishikawa, Tomoyo Amano, Kenji Sakamoto, more

European Journal of Pharmacology > 2017 > 798 > C > 66-71

The aim of this study was to examine whether metformin, a biguanide anti-hyperglycemic drug, dilates retinal blood vessels in rats. Ocular fundus images were captured with an original high-resolution digital fundus camera in vivo and diameters of retinal blood vessels were measured. Both systemic blood pressure and heart rate were continuously recorded. Metformin (0.01–0.3mg/kg/min) increased diameters...

article

l-Citrulline ameliorates cerebral blood flow during cortical spreading depression in rats: Involvement of nitric oxide- and prostanoids-mediated pathway

Yuki Kurauchi, Koichi Mokudai, Asami Mori, Kenji Sakamoto, more

Journal of Pharmacological Sciences > 2017 > 133 > 3 > 146-155

l-Citrulline is a potent precursor of l-arginine, and exerts beneficial effect on cardiovascular system via nitric oxide (NO) production. Migraine is one of the most popular neurovascular disorder, and imbalance of cerebral blood flow (CBF) observed in cortical spreading depression (CSD) contributes to the mechanism of migraine aura. Here, we investigated the effect of l-citrulline on cardiovascular...

article

A delay in vascularization induces abnormal astrocyte proliferation and migration in the mouse retina

Akane Morita, Hiroko Ushikubo, Asami Mori, Shiho Arima, more

Developmental Dynamics > 246 > 3 > 186 - 200

Background: Astrocytes migrate into the retina through the optic nerve head by means of the axons of retinal ganglion cells, and spread radially toward the peripheral retina. Endothelial cells migrate along the astrocyte cellular network to form the retinal surface vasculature. Here, we examined the effects of a delay in retinal vascularization on the migration and proliferation status of astrocytes...

article

Stimulation of β₁- and β₂-adrenoceptors dilates retinal blood vessels in rats

Asami Mori, Akane Sekito, Kenji Sakamoto, Kunio Ishii, more

Naunyn-Schmiedeberg's Archives of Pharmacology > 2017 > 390 > 5 > 527-533

Our previous studies have demonstrated that adrenaline dilates rat retinal arterioles by stimulating propranolol-sensitive β-adrenoceptors and β₃-adrenoceptors, and selective stimulation of β₂- or β₃-adrenoceptors causes retinal vasodilator responses. In the present study, we compared the effects of β₁- and β₂-adrenoceptor stimulation on rat retinal arterioles in vivo. Rat ocular fundus images were...

article

Apelin-36 is protective against N-methyl-D-aspartic-acid-induced retinal ganglion cell death in the mice

Kenji Sakamoto, Yuta Murakami, Shohei Sawada, Hiroko Ushikubo, more

European Journal of Pharmacology > 2016 > 791 > C > 213-220

Retinal ganglion cell death in glaucoma is caused at least in part by a large Ca²⁺ influx through N-methyl-D-aspartic acid (NMDA) receptors. Apelin is a peptide originally found in the tissue extracts of bovine stomach. Recent studies have been shown that apelin protects against the ischemic-reperfused injury in the brain. We examined whether apelin had protective effects on the NMDA-induced retinal...

article

Protective effects of PF‐4708671 against N‐methyl‐d‐aspartic acid‐induced retinal damage in rats

Ikumi Hayashi, Yuto Aoki, Hiroko Ushikubo, Daiki Asano, more

Fundamental & Clinical Pharmacology > 30 > 6 > 529 - 536

We previously demonstrated that rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), protects against N‐methyl‐d‐aspartic acid (NMDA)‐induced retinal damage in rats. Rapamycin inhibits mTOR activity, thereby preventing the phosphorylation of ribosomal protein S6, which is a downstream target of S6 kinase. Therefore, we aimed to determine whether PF‐4708671, an inhibitor of S6 kinase,...

article

Short-term treatment with VEGF receptor inhibitors induces retinopathy of prematurity-like abnormal vascular growth in neonatal rats

Ayuki Nakano, Tsutomu Nakahara, Asami Mori, Hiroko Ushikubo, more

Experimental Eye Research > 2016 > 143 > Complete > 120-131

Retinal arterial tortuosity and venous dilation are hallmarks of plus disease, which is a severe form of retinopathy of prematurity (ROP). In this study, we examined whether short-term interruption of vascular endothelial growth factor (VEGF) signals leads to the formation of severe ROP-like abnormal retinal blood vessels. Neonatal rats were treated subcutaneously with the VEGF receptor (VEGFR) tyrosine...

article

Involvement of prostaglandin I2 in nitric oxide-induced vasodilation of retinal arterioles in rats

Asami Mori, Ryo Namekawa, Masami Hasebe, Maki Saito, more

European Journal of Pharmacology > 2015 > 764 > Complete > 249-255

The soluble guanylyl cyclase/cGMP system plays an important role in the vasodilator response to nitric oxide (NO) in various vascular beds. However, in rat retinal arterioles, the cyclooxygenase-1/cAMP-mediated pathway contributes to the vasodilator effects of NO, although the specific prostanoid involved remains to be elucidated. In the present study, we investigated the role of prostaglandin I₂...

article

Retinal region-dependent susceptibility of capillaries to high-concentration oxygen exposure and vascular endothelial growth factor receptor inhibition in neonatal mice

Naoto Iizuka, Tsutomu Nakahara, Hiroko Ushikubo, Asami Mori, more

Journal of Pharmacological Sciences > 2015 > 129 > 2 > 107-118

Retinal blood flow insufficiency due to capillary loss induces hypoxia in the retina, leading to an abnormal angiogenesis, relating to ischemic retinopathy. To better understand the mechanism and process of retinal capillary regression, we examined the process of hyperoxia- and vascular endothelial growth factor receptor (VEGFR) inhibitor-induced retinal capillary regression in neonatal mice. We also...

article

High-mobility group Box-1 is involved in NMDA-induced retinal injury the in rat retina

Kenji Sakamoto, Aya Mizuta, Kyosuke Fujimura, Yuki Kurauchi, more

Experimental Eye Research > 2015 > 137 > Complete > 63-70

High-mobility group Box-1 (HMGB1) is known to be released from injured cells and to induce an inflammatory response. Although HMGB1 was reported to mediate ischemia-reperfusion injury of the brain, its role in glutamate excitotoxicity of the retina remains controversial. Here, the authors demonstrated the evidence that HMGB1 is involved in the retinal damage induced by NMDA. Under ketamine/xylazine...

article

P2X7 receptor antagonists protect against N-methyl-d-aspartic acid-induced neuronal injury in the rat retina

Kenji Sakamoto, Kanako Endo, Taishi Suzuki, Kyosuke Fujimura, more

European Journal of Pharmacology > 2015 > 756 > Complete > 52-58

Activation of N-methyl-d-aspartic acid (NMDA) receptors followed by a large Ca ²⁺ influx is thought to be a mechanism of glaucoma-induced neuronal cell death. It is possible that damage-associated molecular patterns leak from injured cells, such as adenosine triphosphate, causing retinal ganglion cell death in glaucoma. In the present study, we histologically investigated whether antagonists...

article

Structural and functional changes in retinal vasculature induced by retinal ischemia-reperfusion in rats

Tsutomu Nakahara, Maya Hoshino, Shin-ichiro Hoshino, Asami Mori, more

Experimental Eye Research > 2015 > 135 > Complete > 134-145

Recent studies have shown retinal blood vessel damage in experimental models of retinal degeneration. The present study aimed to provide a detailed description of the structural and functional changes in retinal vasculature induced by retinal ischemia-reperfusion (I/R) in rats. Retinal ischemia was induced for 60 min by raising the intraocular pressure to 130 mmHg. Morphological changes in vascular...

article

l-Citrulline dilates rat retinal arterioles via nitric oxide- and prostaglandin-dependent pathways in vivo

Asami Mori, Masahiko Morita, Koji Morishita, Kenji Sakamoto, more

Journal of Pharmacological Sciences > 2015 > 127 > 4 > 419-423

l-Citrulline is an effective precursor of l-arginine produced by the l-citrulline/l-arginine cycle, and it exerts beneficial effects on the cardiovascular system by supporting enhanced nitric oxide (NO) production. NO dilates retinal blood vessels via the cyclooxygenase-mediated pathway. The purpose of this study was to examine the effects of l-citrulline on retinal circulation and to investigate...

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Search results for: Tsutomu Nakahara

Pharmacological depletion of retinal neurons prevents vertical angiogenic sprouting without affecting the superficial vascular plexus

Transient phenotypic changes in endothelial cells and pericytes in neonatal mouse retina following short‐term blockade of vascular endothelial growth factor receptors

l-Citrulline improves cerebral blood flow in migraine model rats

Opioid receptor activation is involved in neuroprotection induced by TRPV1 channel activation against excitotoxicity in the rat retina

Probucol prevents the attenuation of β₂-adrenoceptor-mediated vasodilation of retinal arterioles in diabetic rats

MEK/ERK- and calcineurin/NFAT-mediated mechanism of cerebral hyperemia and brain injury following NMDA receptor activation

Stimulation of μ-opioid receptors dilates retinal arterioles by neuronal nitric oxide synthase-derived nitric oxide in rats

Anti-diabetic drug metformin dilates retinal blood vessels through activation of AMP-activated protein kinase in rats

l-Citrulline ameliorates cerebral blood flow during cortical spreading depression in rats: Involvement of nitric oxide- and prostanoids-mediated pathway

A delay in vascularization induces abnormal astrocyte proliferation and migration in the mouse retina

Stimulation of β₁- and β₂-adrenoceptors dilates retinal blood vessels in rats

Apelin-36 is protective against N-methyl-D-aspartic-acid-induced retinal ganglion cell death in the mice

Protective effects of PF‐4708671 against N‐methyl‐d‐aspartic acid‐induced retinal damage in rats

Short-term treatment with VEGF receptor inhibitors induces retinopathy of prematurity-like abnormal vascular growth in neonatal rats

Involvement of prostaglandin I2 in nitric oxide-induced vasodilation of retinal arterioles in rats

Retinal region-dependent susceptibility of capillaries to high-concentration oxygen exposure and vascular endothelial growth factor receptor inhibition in neonatal mice

High-mobility group Box-1 is involved in NMDA-induced retinal injury the in rat retina

P2X7 receptor antagonists protect against N-methyl-d-aspartic acid-induced neuronal injury in the rat retina

Structural and functional changes in retinal vasculature induced by retinal ischemia-reperfusion in rats

l-Citrulline dilates rat retinal arterioles via nitric oxide- and prostaglandin-dependent pathways in vivo

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