751
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Ichikawa K, Tagawa Y, Kawai M, Asamoto M, Shirai T. Promoting Effects of Streptozotocin-induced Diabetes on Induction of Hepatic Preneoplastic Lesions by Diethylnitrosamine in Rats. J Toxicol Pathol 2010; 23:125-31. [PMID: 22272023 PMCID: PMC3234616 DOI: 10.1293/tox.23.125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Accepted: 05/14/2010] [Indexed: 01/04/2023] Open
Abstract
The effects of streptozotocin (STZ)-induced diabetes on induction of hepatic
preneoplastic lesions by diethylnitrosamine (DEN) were investigated in male
Fischer rats. A single dose of STZ was injected intravenously either 2
weeks before or after initiation with DEN. The blood glucose levels were
significantly elevated from 1 week after STZ-injection until autopsy. The
numbers of GST-P positive foci at 1 week after DEN administration in the
STZ-injected rats were similar to those in the non-diabetic rats. In
contrast, both the numbers and areas of GST-P positive foci > 2 mm in
diameter 8 weeks after DEN administration were increased significantly in
the rats treated with STZ after DEN exposure compared with the non-diabetic
control rats. The results suggest that hepatic preneoplastic lesions
initiated with DEN are promoted by STZ treatment-inducing diabetes.
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Affiliation(s)
- Kazuhito Ichikawa
- Drug Safety Management Department, Sanwa Kagaku Kenkyusho
Co., Ltd., 35 Higashisotobori-cho, Higashi-ku, Nagoya 461-8631, Japan
- Department of Experimental Pathology and Tumor Biology,
Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku,
Nagoya 467-8601, Japan
| | - Yoshiaki Tagawa
- Pharmaceutical Research Laboratories, Sanwa Kagaku
Kenkyusho Co., Ltd., 363 Shiosaki, Hokusei-cho, Inabe-shi, Mie 511-0406,
Japan
| | - Masaomi Kawai
- Pharmaceutical Research Laboratories, Sanwa Kagaku
Kenkyusho Co., Ltd., 363 Shiosaki, Hokusei-cho, Inabe-shi, Mie 511-0406,
Japan
| | - Makoto Asamoto
- Department of Experimental Pathology and Tumor Biology,
Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku,
Nagoya 467-8601, Japan
| | - Tomoyuki Shirai
- Department of Experimental Pathology and Tumor Biology,
Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku,
Nagoya 467-8601, Japan
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752
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Singh AK, Singh J. Evaluation of anti-diabetic potential of leaves and stem of Flacourtia jangomas in streptozotocin-induced diabetic rats. Indian J Pharmacol 2010; 42:301-5. [PMID: 21206623 PMCID: PMC2959214 DOI: 10.4103/0253-7613.70238] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2009] [Revised: 06/14/2010] [Accepted: 07/16/2010] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVES To study the efficacy of combination of Flacourtia jangomas leaf and stem (1:1) methanolic extract (MEFJ) in streptozotocin (STZ)-induced diabetic rats and to investigate the qualitative phytochemical present in the extract. The study also aims to evaluate acute and short-term general toxicity of the extract in rats. MATERIAL AND METHODS MEFJ of leaves and stem was subjected to preliminary qualitative phytochemical investigations by using standard procedures. The extract (400 mg/kg p.o.) was screened for antidiabetic activity in STZ-induced diabetic rats (30 mg/kg, i.p.). Acute oral toxicity study for the test extract of the plant was carried out using OECD/OCED guideline 425. RESULTS Phytochemical analysis of MEFJ of leaves and stem revealed the presence of flavonoids, saponins, carbohydrates, steroids, tannins, and phenolic compounds. In acute toxicity study, no toxic symptoms were observed for MEFJ up to dose 2000 mg/kg. Oral administration of MEFJ for 21 days exhibited highly significant (P < 0.01) hypoglycemic activity and also correction of altered biochemical parameters, namely cholesterol and triglycerides significantly (P < 0.05). Urine analysis on 1(st) day showed the presence of glucose and traces of ketone in the entire group except normal control group. However, on 21(st) day glucose and ketone traces were absent in MEFJ- and glibenclamide-treated groups while they were present in diabetic control. The data were analyzed using analysis of variance followed by Dunnett's test. CONCLUSION The observations confirm that methanolic extract of the leaf and stem of the plant has antidiabetic activity and is also involved in correction of altered biological parameters. It also warrants further investigation to isolate and identify the hypoglycemic principles in this plant so as to elucidate their mode of action.
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Affiliation(s)
- Ajay Kumar Singh
- Department of Pharmacology, School of Pharmaceutical Sciences, Jaipur National University, Jaipur 302 025, Rajasthan, India
| | - Jyoti Singh
- Department of Pharmacology, School of Pharmaceutical Sciences, Jaipur National University, Jaipur 302 025, Rajasthan, India
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753
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Li F, Wang CH, Wang JG, Thai T, Boysen G, Xu L, Turner AL, Wolberg AS, Mackman N, Maeda N, Takahashi N. Elevated tissue factor expression contributes to exacerbated diabetic nephropathy in mice lacking eNOS fed a high fat diet. J Thromb Haemost 2010; 8:2122-32. [PMID: 20626618 PMCID: PMC5744483 DOI: 10.1111/j.1538-7836.2010.03976.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Human eNOS (NOS3) polymorphisms that lower its expression are associated with advanced diabetic nephropathy (DN), and the lack of eNOS accelerates DN in diabetic mice. Diabetes is associated with fibrin deposition. Lack of nitric oxide and fatty acids stimulates the NF-kB pathway, which increases tissue factor (TF). OBJECTIVES To test the hypothesis that TF contributes to the severity of DN in the diabetic eNOS(-/-) mice fed a high-fat diet (HF). METHODS We made eNOS(-/-) and wild-type mice diabetic with streptozotocin. Half of them were placed on HF. RESULTS Blood glucose levels were not affected by either the diet or eNOS genotype. Lack of eNOS in the diabetic mice increased urinary albumin excretion, glomerulosclerosis, interstitial fibrosis, and glomerular basement membrane thickness. HF by itself did not affect DN in the wild-type mice, but significantly enhanced DN in eNOS(-/-) mice. More than half of diabetic eNOS(-/-) mice on HF died prematurely with signs of thrombotic complications. Diabetic kidneys contained fibrin and TF, and their levels were increased by the lack of eNOS and by HF in an additive fashion. The HF diet increased the kidney expression of inflammatory genes. The increase in TF preceded DN, and administration of an anti-mouse TF antibody to diabetic mice reduced the expression of inflammatory genes. CONCLUSION Together, these data indicate a causal link between TF and the exacerbation of DN in eNOS(-/-) mice. The condition is significantly worsened by enhanced inflammatory responses to an HF diet via TF.
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Affiliation(s)
- Feng Li
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Chih-Hong Wang
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Jian-Guo Wang
- Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Tiffany Thai
- Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Gunnar Boysen
- Center of Environmental Health and Susceptibility, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Longquan Xu
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Adam L Turner
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Alisa S. Wolberg
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Nigel Mackman
- Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Nobuyo Maeda
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Nobuyuki Takahashi
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
- Department of Cell and Molecular Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
- Tohoku University, Graduate Schools of Pharmaceutical Sciences and Medicine, Sendai, 980-8578, Japan
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754
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Ivanović-Matić S, Mihailović M, Dinić S, Martinović V, Bogojević D, Grigorov I, Poznanović G. The absence of cardiomyopathy is accompanied by increased activities of CAT, MnSOD and GST in long-term diabetes in rats. J Physiol Sci 2010; 60:259-66. [PMID: 20422335 PMCID: PMC10717544 DOI: 10.1007/s12576-010-0093-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 04/06/2010] [Indexed: 10/19/2022]
Abstract
The activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST), the incidence of DNA damage, the activation of poly (ADP-ribose) polymerase-1 (PARP-1), a marker of DNA repair, and connective tissue growth factor (CTGF), a marker of tissue fibrosis, were examined in the hearts of rats for 16 weeks after diabetes induction by streptozotocin (STZ) administration. A 150% increase in CAT activity was detected at the end of the 2nd week post-STZ administration, and CAT activity remained 80% above the control level throughout 16 weeks. While total SOD and CuZn-SOD exhibited progressively decreasing activities, those of Mn-SOD and GST were elevated. Neither DNA strand breaks (apoptosis or necrosis) nor changes in PARP-1 activity and in CTGF levels (fibrosis) were observed in the diabetic heart. The absence of cardiomyopathy is accompanied with increased activities of CAT, MnSOD and GST.
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Affiliation(s)
- Svetlana Ivanović-Matić
- Department of Molecular Biology, Institute for Biological Research, University of Belgrade, Despot Stephen Blvd. 142, 11060, Belgrade, Serbia.
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755
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Erejuwa OO, Sulaiman SA, Wahab MSA, Salam SKN, Salleh MSM, Gurtu S. Antioxidant protective effect of glibenclamide and metformin in combination with honey in pancreas of streptozotocin-induced diabetic rats. Int J Mol Sci 2010; 11:2056-66. [PMID: 20559501 PMCID: PMC2885093 DOI: 10.3390/ijms11052056] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 04/24/2010] [Accepted: 04/26/2010] [Indexed: 01/11/2023] Open
Abstract
Hyperglycemia exerts toxic effects on the pancreatic beta-cells. This study investigated the hypothesis that the common antidiabetic drugs glibenclamide and metformin, in combination with tualang honey, offer additional protection for the pancreas of streptozotocin (STZ)-induced diabetic rats against oxidative stress and damage. Diabetes was induced in male Sprague Dawley rats by a single dose of STZ (60 mg/kg; ip). Diabetic rats had significantly elevated levels of lipid peroxidation (TBARS), up-regulated activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) while catalase (CAT) activity was significantly reduced. Glibenclamide and metformin produced no significant effects on TBARS and antioxidant enzymes except GPx in diabetic rats. In contrast, the combination of glibenclamide, metformin and honey significantly up-regulated CAT activity and down-regulated GPx activity while TBARS levels were significantly reduced. These findings suggest that tualang honey potentiates the effect of glibenclamide and metformin to protect diabetic rat pancreas against oxidative stress and damage.
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Affiliation(s)
- Omotayo Owomofoyon Erejuwa
- Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia; E-Mails:
(S.A.S.);
(M.S.A.W.)
| | - Siti Amrah Sulaiman
- Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia; E-Mails:
(S.A.S.);
(M.S.A.W.)
| | - Mohd Suhaimi Abdul Wahab
- Department of Pharmacology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia; E-Mails:
(S.A.S.);
(M.S.A.W.)
| | | | - Md Salzihan Md Salleh
- Department of Pathology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia; E-Mail:
| | - Sunil Gurtu
- School of Medicine and Health Sciences, Monash University Sunway Campus, Jalan Lagoon Selatan, 46150, Bandar Sunway, Selangor, Malaysia; E-Mail:
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756
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Gangula PRR, Mukhopadhyay S, Ravella K, Cai S, Channon KM, Garfield RE, Pasricha PJ. Tetrahydrobiopterin (BH4), a cofactor for nNOS, restores gastric emptying and nNOS expression in female diabetic rats. Am J Physiol Gastrointest Liver Physiol 2010; 298:G692-9. [PMID: 20185690 PMCID: PMC2867432 DOI: 10.1152/ajpgi.00450.2009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Accepted: 02/18/2010] [Indexed: 01/31/2023]
Abstract
Gastroparesis is a debilitating disease predominantly affecting young women. Recently, dysregulation of neuronal nitric oxide synthase (nNOS) in myenteric plexus neurons has been implicated for delayed solid gastric emptying/gastroparesis in diabetic patients. In this study, we have explored the role of tetrahydrobiopterin (BH4), a major cofactor for nNOS activity and NO synthesis in diabetic gastroparesis. Diabetes was induced with single injection of streptozotocin (55 mg/kg body wt, ip) in female rats, with experiments performed on week 3 or 9 following induction, with or without 3-wk BH4 supplementation. Gastric pyloric BH4 levels were significantly decreased in diabetic female rats compared with control (18.6 +/- 1.45 vs. 31.0 +/- 2.31 pmol/mg protein). In vitro studies showed that 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of BH4 synthesis, significantly decreased gastric NO release and nitrergic relaxation. Three-week dietary supplementation of BH4 either from day 1 or week 6 significantly attenuated diabetes-induced delayed gastric emptying for solids (3 wk: BH4, 67 +/- 6.7 vs. diabetic, 36.05 +/- 7.09; 9 wk: BH4, 57 +/- 8.45 vs. diabetic, 33 +/- 9.91) and diabetes-induced reduction in pyloric nNOS-alpha protein expression in female rats. Supplementation of BH4 significantly restored gastric nNOS-alpha dimerization in 9-wk-old diabetic female rats. In addition, BH4 treatment reversed (17.23 +/- 5.81 vs. 42.0 +/- 2.70 mmHg x s) the diabetes-induced changes in intragastric pressures (IGP) and gastric pyloric nitrergic relaxation (-0.62 +/- 0.01 vs. -0.22 +/- 0.07). BH4 deficiency plays a critical role in diabetes-induced alterations including delayed solid gastric emptying, increased IGP, reduced pyloric nitrergic relaxation, and nNOS-alpha expression in female rats. Supplementation of BH4 accelerates gastric emptying by restoring nitrergic system in diabetic female rats. Therefore, BH4 supplementation is a potential therapeutic option for female patients of diabetic gastroparesis.
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Affiliation(s)
- Pandu R R Gangula
- Department of Obstetrics and Gynecology, Center for Women's Health Research, Meharry Medical College, Nashville, Tennessee 37208, USA.
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757
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Gandhi GK, Ball KK, Cruz NF, Dienel GA. Hyperglycaemia and diabetes impair gap junctional communication among astrocytes. ASN Neuro 2010; 2:e00030. [PMID: 20396375 DOI: 10.1042/AN20090048] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 01/03/2010] [Accepted: 01/05/2010] [Indexed: 01/21/2023] Open
Abstract
Sensory and cognitive impairments have been documented in diabetic humans and
animals, but the pathophysiology of diabetes in the central nervous system is
poorly understood. Because a high glucose level disrupts gap junctional
communication in various cell types and astrocytes are extensively coupled by
gap junctions to form large syncytia, the influence of experimental diabetes on
gap junction channel-mediated dye transfer was assessed in astrocytes in tissue
culture and in brain slices from diabetic rats. Astrocytes grown in
15–25 mmol/l glucose had a slow-onset, poorly reversible decrement in
gap junctional communication compared with those grown in 5.5 mmol/l glucose.
Astrocytes in brain slices from adult STZ (streptozotocin)-treated rats at
20–24 weeks after the onset of diabetes also exhibited reduced dye
transfer. In cultured astrocytes grown in high glucose, increased oxidative
stress preceded the decrement in dye transfer by several days, and gap
junctional impairment was prevented, but not rescued, after its manifestation by
compounds that can block or reduce oxidative stress. In sharp contrast with
these findings, chaperone molecules known to facilitate protein folding could
prevent and rescue gap junctional impairment, even in the presence of elevated
glucose level and oxidative stress. Immunostaining of Cx (connexin) 43 and 30,
but not Cx26, was altered by growth in high glucose. Disruption of astrocytic
trafficking of metabolites and signalling molecules may alter interactions among
astrocytes, neurons and endothelial cells and contribute to changes in brain
function in diabetes. Involvement of the microvasculature may contribute to
diabetic complications in the brain, the cardiovascular system and other
organs.
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Key Words
- 4-PBA, 4-phenylbutyric acid
- 6-NBDG, 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose
- Cx, connexin
- DCF, 2′,7′-dichlorodihydrofluorescein
- DIC, differential interference contrast
- DMEM, Dulbecco's modified Eagle's medium
- ER, endoplasmic reticulum
- FBS, fetal bovine serum
- LYCH, Lucifer Yellow CH
- LYVS, Lucifer Yellow VS
- MnTBAP, manganese(III) tetrakis (4-benzoic acid) porphyrin chloride
- NA, numerical aperture
- NOS, nitric oxide synthase
- PKC, protein kinase C
- RNS, reactive nitrogen species
- ROS, reactive oxygen species
- STZ, streptozotocin
- TMAO, trimethylamine N-oxide dihydrate
- TUDCA, tauroursodeoxycholic acid
- aCSF, artificial cerebrospinal fluid
- astrocyte
- carboxy-DCF-DA, carboxy DCF diacetate
- connexin (Cx)
- dBcAMP, dibutyryl cAMP
- diabetes
- gap junction
- hyperglycaemia
- l-NAME, l-Nω-nitro-l-arginine methyl ester
- streptozotocin
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758
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Hawkins RA, Mokashi A, Dejoseph MR, Viña JR, Fernstrom JD. Glutamate permeability at the blood-brain barrier in insulinopenic and insulin-resistant rats. Metabolism 2010; 59:258-66. [PMID: 19793593 PMCID: PMC2813370 DOI: 10.1016/j.metabol.2009.07.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 05/29/2009] [Accepted: 07/24/2009] [Indexed: 02/07/2023]
Abstract
The influence of diabetes on brain glutamate (GLU) uptake was studied in insulinopenic (streptozotocin [STZ]) and insulin-resistant (diet-induced obesity [DIO]) rat models of diabetes. In the STZ study, adult male Sprague-Dawley rats were treated with STZ (65 mg/kg intravenously) or vehicle and studied 3 weeks later. The STZ rats had elevated plasma levels of glucose, ketone bodies, and branched-chain amino acids; brain uptake of GLU was very low in both STZ and control rats, examined under conditions of normal and greatly elevated (by intravenous infusion) plasma GLU concentrations. In the DIO study, rats ingested a palatable, high-energy diet for 2 weeks and were then divided into weight tertiles: rats in the heaviest tertile were designated DIO; rats in the lightest tertile, diet-resistant (DR); and rats in the intermediate tertile, controls. The DIO and DR rats continued to consume the high-energy diet for 4 more weeks, whereas the control rats were switched to standard rat chow. All rats were studied at 6 weeks (subgroups were examined under conditions of normal or elevated plasma GLU concentrations). The DIO rats ate more food and were heavier than the DR or control rats and had higher plasma leptin levels and insulin-glucose ratios. In all diet groups, the blood-brain barrier showed very low GLU penetration and was unaffected by plasma GLU concentration. Brain GLU uptake also did not differ among the diet groups. Together, the results indicate that the blood-brain barrier remains intact to the penetration of GLU in 2 models of diabetes under the conditions examined.
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Affiliation(s)
- Richard A Hawkins
- Department of Physiology and Biophysics, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064-3095, USA.
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759
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Ionut V, Liu H, Mooradian V, Castro AVB, Kabir M, Stefanovski D, Zheng D, Kirkman EL, Bergman RN. Novel canine models of obese prediabetes and mild type 2 diabetes. Am J Physiol Endocrinol Metab 2010; 298:E38-48. [PMID: 19843874 PMCID: PMC2806110 DOI: 10.1152/ajpendo.00466.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Human type 2 diabetes mellitus (T2DM) is often characterized by obesity-associated insulin resistance (IR) and beta-cell function deficiency. Development of relevant large animal models to study T2DM is important and timely, because most existing models have dramatic reductions in pancreatic function and no associated obesity and IR, features that resemble more T1DM than T2DM. Our goal was to create a canine model of T2DM in which obesity-associated IR occurs first, followed by moderate reduction in beta-cell function, leading to mild diabetes or impaired glucose tolerance. Lean dogs (n = 12) received a high-fat diet that increased visceral (52%, P < 0.001) and subcutaneous (130%, P < 0.001) fat and resulted in a 31% reduction in insulin sensitivity (S(I)) (5.8 +/- 0.7 x 10(-4) to 4.1 +/- 0.5 x 10(-4) microU x ml(-1) x min(-1), P < 0.05). Animals then received a single low dose of streptozotocin (STZ; range 30-15 mg/kg). The decrease in beta-cell function was dose dependent and resulted in three diabetes models: 1) frank hyperglycemia (high STZ dose); 2) mild T2DM with normal or impaired fasting glucose (FG), 2-h glucose >200 mg/dl during OGTT and 77-93% AIR(g) reduction (intermediate dose); and 3) prediabetes with normal FG, normal 2-h glucose during OGTT and 17-74% AIR(g) reduction (low dose). Twelve weeks after STZ, animals without frank diabetes had 58% more body fat, decreased beta-cell function (17-93%), and 40% lower S(I). We conclude that high-fat feeding and variable-dose STZ in dog result in stable models of obesity, insulin resistance, and 1) overt diabetes, 2) mild T2DM, or 3) impaired glucose tolerance. These models open new avenues for studying the mechanism of compensatory changes that occur in T2DM and for evaluating new therapeutic strategies to prevent progression or to treat overt diabetes.
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Affiliation(s)
- Viorica Ionut
- Dept. of Physiology and Biophysics, Keck School of Medicine, Univ. of Southern California, 1333 San Pablo St., Los Angeles, CA 90033, USA.
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760
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Saisho Y, Butler AE, Manesso E, Galasso R, Zhang L, Gurlo T, Toffolo GM, Cobelli C, Kavanagh K, Wagner JD, Butler PC. Relationship between fractional pancreatic beta cell area and fasting plasma glucose concentration in monkeys. Diabetologia 2010; 53:111-4. [PMID: 19847395 PMCID: PMC2789926 DOI: 10.1007/s00125-009-1552-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 08/27/2009] [Indexed: 12/17/2022]
Abstract
AIMS/HYPOTHESIS We sought to establish the relationship between fasting plasma glucose concentrations and pancreatic fractional beta cell area in adult cynomolgus monkeys (Macaca fascicularis). METHODS Fasting plasma glucose and pancreatic fractional beta cell area were measured in 18 control and 17 streptozotocin-treated adult primates (17.0 +/- 1.2 vs 15.4 +/- 1.2 years old). RESULTS Fasting plasma glucose was increased (12.0 +/- 2.0 vs 3.4 +/- 0.1 mmol/l, p < 0.01) and fractional beta cell area was decreased (0.62 +/- 0.13% vs 2.49 +/- 0.35%, p < 0.01) in streptozotocin-treated monkeys. The relationship between fasting plasma glucose and pancreatic fractional beta cell area was described by a wide range of beta cell areas in controls. In streptozotocin-treated monkeys there was an inflection of fasting blood glucose at approximately 50% of the mean beta cell area in controls with a steep increase in blood glucose for each further decrement in beta cell area. CONCLUSIONS/INTERPRETATION In adult non-human primates a decrement in fractional beta cell area of approximately 50% or more leads to loss of glycaemic control.
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Affiliation(s)
- Y. Saisho
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Place #A, Los Angeles, CA 90024-2852 USA
| | - A. E. Butler
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Place #A, Los Angeles, CA 90024-2852 USA
| | - E. Manesso
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Place #A, Los Angeles, CA 90024-2852 USA
- Department of Information Engineering, University of Padova, Padua, Italy
| | - R. Galasso
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Place #A, Los Angeles, CA 90024-2852 USA
| | - L. Zhang
- Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC USA
| | - T. Gurlo
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Place #A, Los Angeles, CA 90024-2852 USA
| | - G. M. Toffolo
- Department of Information Engineering, University of Padova, Padua, Italy
| | - C. Cobelli
- Department of Information Engineering, University of Padova, Padua, Italy
| | - K. Kavanagh
- Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC USA
| | - J. D. Wagner
- Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC USA
| | - P. C. Butler
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 900 Weyburn Place #A, Los Angeles, CA 90024-2852 USA
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761
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Singh R. Antihyperglycemic effect of ethanolic extract and fractions of anacardium occidentale L. Stem bark in streptozotocin-induced diabetic rats. J Basic Clin Pharm 2009; 1:16-9. [PMID: 25206248 PMCID: PMC4158895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 01/29/2010] [Accepted: 02/02/2010] [Indexed: 12/02/2022] Open
Abstract
The numbers of adults with diabetes in the world is estimated to rise 300 millions in the year 2025 and this leads to increasing search for better anti-diabetic drug. The effects of the ethanol extract (1.25 g/kg) and fractions (Ethyl acetate, dichloromethane and butanol in the dose of 1 g/kg) of Anacardium occidentale stem bark on the blood glucose levels in streptozotocin-induced types 1 and 2 diabetic rats at different prandial states were studied. The ethanol extract of A. occidentale had no hypoglycemic effect in type 1 diabetic rats in fasting and postprandial glucose load conditions and, in type 2 diabetic rats in fasting condition. However, the extract, significantly lowered blood glucose levels in type 2 diabetic rats when fed simultaneously with glucose. The ethyl acetate fraction showed a significant opposing effect in serum glucose rise after administration of glucose. Additionally, its dichloromethane extract also exhibited a significant reduction in serum glucose level compared to control after glucose administration while its butanol fraction was devoid of this activity. These findings conclude that the active principles responsible for the antihyperglycaemic effect might be concentrated in the ethyl acetate and dichloromethane fractions of the extract.
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Affiliation(s)
- Ramnik Singh
- Khalsa College of Pharmacy, Amritsar-143002, Punjab, INDIA,Corresponding Author: E-mail:
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762
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Abstract
UNLABELLED Untreated type 1 diabetes increases hepatic drug metabolism in both human patients and rodent models. We used knockout mice to test the role of the nuclear xenobiotic receptors constitutive androstane receptor (CAR) and pregnane and xenobiotic receptor (PXR) in this process. Streptozotocin-induced diabetes resulted in increased expression of drug metabolizing cytochrome P450s and also increased the clearance of the cytochrome P450 substrate zoxazolamine. This induction was completely absent in Car(-/-) mice, but was not affected by the loss of PXR. Among the many effects of diabetes on the liver, we identified bile acid elevation and activated adenosine monophosphate-activated protein kinase as potential CAR-activating stimuli. Expression of the CAR coactivator peroxisome proliferator-activated receptor gamma coactivator (PGC)-1alpha was also increased in mouse models of type 1 diabetes. CONCLUSION The CAR-dependent induction of drug metabolism in newly diagnosed or poorly managed type 1 diabetes has the potential for significant impact on the efficacy or toxicity of therapeutic agents.
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Affiliation(s)
- Bingning Dong
- Department of Molecular and Cellular Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030
| | - Mohammed Qatanani
- Department of Molecular and Cellular Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030
| | - David D. Moore
- Department of Molecular and Cellular Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030,Corresponding author: , 713-798-3310, fax 713-798-3017
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763
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Abstract
Insulin-induced severe hypoglycemia causes brain damage. The hypothesis to be tested was that diabetes portends to more extensive brain tissue damage following an episode of severe hypoglycemia. Nine-week-old male streptozotocin-diabetic (DIAB; n = 10) or vehicle-injected control (CONT; n = 7) Sprague-Dawley rats were subjected to hyperinsulinemic (0.2 U.kg(-1).min(-1)) severe hypoglycemic (10-15 mg/dl) clamps while awake and unrestrained. Groups were precisely matched for depth and duration (1 h) of severe hypoglycemia (CONT 11 +/- 0.5 and DIAB 12 +/- 0.2 mg/dl, P = not significant). During severe hypoglycemia, an equal number of episodes of seizure-like activity were noted in both groups. One week later, histological analysis demonstrated extensive neuronal damage in regions of the hippocampus, especially in the dentate gyrus and CA1 regions and less so in the CA3 region (P < 0.05), although total hippocampal damage was not different between groups. However, in the cortex, DIAB rats had significantly (2.3-fold) more dead neurons than CONT rats (P < 0.05). There was a strong correlation between neuronal damage and the occurrence of seizure-like activity (r(2) > 0.9). Separate studies conducted in groups of diabetic (n = 5) and nondiabetic (n = 5) rats not exposed to severe hypoglycemia showed no brain damage. In summary, under the conditions studied, severe hypoglycemia causes brain damage in the cortex and regions within the hippocampus, and the extent of damage is closely correlated to the presence of seizure-like activity in nonanesthetized rats. It is concluded that, in response to insulin-induced severe hypoglycemia, diabetes uniquely increases the vulnerability of specific brain areas to neuronal damage.
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Affiliation(s)
- Adam J Bree
- Division of Endocrinology, Metabolism, & Lipid Research, Washington University in St. Louis, Campus Box 8127, 660 South Euclid Ave., St. Louis, MO 63110, USA
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764
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Li JX, Koek W, France CP. Food restriction and streptozotocin differentially modify sensitivity to the hypothermic effects of direct- and indirect-acting serotonin receptor agonists in rats. Eur J Pharmacol 2009; 613:60-3. [PMID: 19379724 PMCID: PMC2735871 DOI: 10.1016/j.ejphar.2009.04.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 04/02/2009] [Accepted: 04/09/2009] [Indexed: 11/23/2022]
Abstract
Food restriction and experimentally-induced diabetes (streptozotocin) can modify serotonin (5-HT) neurotransmission and sensitivity to drugs acting on 5-HT systems. This study examined the effects of food restriction and streptozotocin on the hypothermic effects of the 5-HT(1A) receptor agonist (+)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT), the 5-HT(2) receptor agonist (+/-)-2,5-dimethoxy-4-methylamphetamine hydrochloride (DOM), the 5-HT releaser fenfluramine, and the selective 5-HT reuptake inhibitor (SSRI) fluoxetine. All four drugs significantly decreased body temperature in free feeding rats. Limiting rats to 10 g/day of food for 7 days decreased body weight and sensitivity to 8-OH-DPAT induced hypothermia, without affecting sensitivity to DOM, fenfluramine, or fluoxetine induced hypothermia. Subsequently, 7 days of free feeding restored body weight and sensitivity to 8-OH-DPAT. Sensitivity to all drugs was significantly decreased 7 days after 50 mg/kg streptozotocin; subsequently, 10 days of insulin replacement restored sensitivity to all drugs. These results extend to body temperature the observation that food restriction and experimentally-induced diabetes differentially modify sensitivity to drugs acting on 5-HT systems and they further suggest that the clinical response to therapeutic drugs acting on 5-HT systems might be impacted by nutritional and insulin status.
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Affiliation(s)
- Jun-Xu Li
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, USA
| | - Wouter Koek
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, USA
- Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, USA
| | - Charles P. France
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, USA
- Department of Psychiatry, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229, USA
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765
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Wang M, Wang P, Peng JL, Wu S, Zhao XP, Li L, Shen GX. The altered expression of glucose-regulated proteins 78 in different phase of streptozotocin-affected pancreatic beta-cells. Cell Stress Chaperones 2009; 14:43-8. [PMID: 18597185 PMCID: PMC2673903 DOI: 10.1007/s12192-008-0053-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 04/06/2008] [Accepted: 05/12/2008] [Indexed: 11/24/2022] Open
Abstract
Endoplasmic reticulum (ER) stress-mediated apoptosis plays an important role in the destruction of pancreatic beta-cells and contributes to the development of type 1 diabetes. The chaperone molecule, glucose-regulated proteins 78 (Grp78), is required to maintain ER function during toxic insults. In this study, we investigated the changes of Grp78 expression in different phases of streptozotocin (STZ)-affected beta-cells to explore the relationship between Grp78 and the response of beta-cells to ER stress. An insulinoma cell line (NIT-1) treated with STZ for different time periods and STZ-induced diabetic Balb/C mice at different time points were used as the model system. The level of Grp78 and C/EBP homologous protein (CHOP) mRNA were detected by real-time polymerase chain reaction and their protein by immunoblot. Apoptosis and necrosis was measured by flow cytometry. In addition, the changes of Grp78 protein in STZ-treated nondiabetic mice were also detected by immunoblot. Grp78 expression significantly increased in the early phase but decreased in the later phase of affected beta-cells, while CHOP was induced and apoptosis occurred along with the decrease of Grp78. Interestingly, the Grp78 protein of STZ-treated nondiabetic mice increased stably compared with that of the control. From the results, we can conclude that Grp78 may contribute to the response of beta-cells to ER stress, and more attention should be paid to Grp78 in the improvement of diabetes.
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Affiliation(s)
- Min Wang
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
- Department of Basic Medical Science, Hubei College of Traditional Chinese Medicine, Wuhan, 430065 China
| | - Ping Wang
- Department of Adult Internal Medicine, Hubei Maternal and Child Health Hospital, Wuhan, 430070 China
| | - Ji-Lin Peng
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Sha Wu
- Department of Immunology, Southern Medical University, Guangzhou, 510182 China
| | - Xiao-Ping Zhao
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Li Li
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
| | - Guan-Xin Shen
- Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030 China
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766
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Singh SK, Rai PK, Jaiswal D, Watal G. Evidence-based Critical Evaluation of Glycemic Potential of Cynodon dactylon. Evid Based Complement Alternat Med 2008; 5:415-20. [PMID: 18955211 PMCID: PMC2586314 DOI: 10.1093/ecam/nem044] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Accepted: 03/08/2007] [Indexed: 11/15/2022]
Abstract
The present study is an extension of our previous work carried out on Cynodon dactylon. This study deals with the critical evaluation of glycemic potential of ethanolic extract of defatted C. dactylon. The doses of 250, 500 and 750 mg kg(-1) bw of the extract were administered orally to normal as well as Streptozotocin-induced diabetic rats to study its glycemic potential. The effect of repeated oral administration of the same doses of ethanolic extract was also studied on serum lipid profile of severely diabetic (SD) rats. The dose of 500 mg kg(-1) bw was identified as the most effective dose as it lowered the blood glucose levels of normal by 42.12% and of diabetic by 43.42% during fasting blood glucose (FBG) and glucose tolerance test respectively. The SD rats were also treated daily with this identified dose of 500 mg kg(-1) bw for 2 weeks and a significant reduction of 56.34% was observed in FBG level. Total cholesterol, low density lipoprotein and triglyceride levels were also decreased by 32.94, 64.06 and 48.46% respectively in SD rats whereas, cardioprotective high density lipoprotein increased by 16.45%. The reduced urine sugar level and increased body weight are additional advantages. These evidences clearly indicate that the ethanolic extract of defatted C. dactylon has high antidiabetic potential along with good hypolipidemic profile.
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767
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Mohammadi J, Naik PR. Evaluation of hypoglycemic effect of Morus alba in an animal model. Indian J Pharmacol 2008; 40:15-8. [PMID: 21264155 PMCID: PMC3023115 DOI: 10.4103/0253-7613.40483] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2007] [Revised: 01/10/2008] [Accepted: 03/07/2008] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVE The objective of the present investigation was to evaluate the therapeutic efficacy of mulberry leaves in an animal model of diabetes. MATERIALS AND METHODS Animals were treated with mulberry leaf extract 400 mg and 600 mg/kg body weight for 35 days. Blood glucose, glycosylated hemoglobin, triglyceride, LDL, VLDL, HDL, blood urea, cholesterol, number of β cells, and diameter of the islets of Langerhans were measured at the beginning and at the end of the experiment. RESULTS Blood glucose level and other parameters (except HDL) were elevated in the diabetic group, but were brought to control group level in the diabetic group treated with 600 mg/kg body weight of mulberry leaf extract. The diameter of the islets and the number of β cells were reduced in the diabetic group; both parameters were brought to control group level after treatment with mulberry leaf extract. CONCLUSION Mulberry leaf extract, at a dose of 600 mg/kg body weight, has therapeutic effects in diabetes-induced Wistar rats and can restore the diminished β cell numbers.
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Affiliation(s)
- Jamshid Mohammadi
- Endocrinology Laboratory, Department of Zoology, University of Mysore, Mysore - 570 006, India
| | - Prakash R. Naik
- Endocrinology Laboratory, Department of Zoology, University of Mysore, Mysore - 570 006, India
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768
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Shim JY, Kim KO, Seo BH, Lee HS. Soybean isoflavone extract improves glucose tolerance and raises the survival rate in streptozotocin-induced diabetic rats. Nutr Res Pract 2007; 1:266-72. [PMID: 20368949 PMCID: PMC2849033 DOI: 10.4162/nrp.2007.1.4.266] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 11/20/2007] [Accepted: 11/28/2007] [Indexed: 11/09/2022] Open
Abstract
The present study evaluated the effect of various dosages of soybean isoflavone extract on body weight changes, glucose tolerance and liver function in streptozotocin-induced diabetic rats. One group of normal rats (normal control) was fed an AIN-76-based experimental diet and four groups of diabetic rats were fed the same diet supplemented with four different levels of soybean isoflavone extract for seven weeks. The daily dosages of pure isoflavone for four diabetic groups were set to be 0 mg (diabetic control), 0.5 mg (ISO-I), 3.0 mg (ISO-II) and 30.0 mg (ISO-III) per kilogram of body weight, respectively. The daily consumption of isoflavone at the level of 3.0mg per kilogram of body weight resulted in the suppression of body weight loss and increased the survival rate of diabetic animals one and half times compared to that of the diabetic control group. Blood glucose levels in a fasting state and after the oral administration of glucose were significantly lower in the ISO-II group during the oral glucose tolerance test. The ISO-II group showed a tendency to elongate the gastrointestinal transit time. The activity of serum aminotransferases, indicator of liver function, was not negatively affected by any intake level of isoflavone. The present study demonstrated that the soybean isoflavone extract may be beneficial to diabetic animals by improving their glucose tolerance and suppressing weight loss without incurring hepatotoxicity at the daily dosage of 3.0 mg per kg of body weight.
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Affiliation(s)
- Jee-Youn Shim
- Department of Food Science and Nutrition, Kyungpook National University, Daegu 702-701, Korea
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769
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Wölkart G, Pang X, Stessel H, Kirchengast M, Brunner F. Chronic endothelin-A receptor antagonism is as protective as angiotensin converting enzyme inhibition against cardiac dysfunction in diabetic rats. Br J Pharmacol 2007; 151:1187-97. [PMID: 17572700 PMCID: PMC2189828 DOI: 10.1038/sj.bjp.0707325] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Revised: 04/23/2007] [Accepted: 05/02/2007] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Diabetes mellitus is associated with a specific cardiomyopathy. We compared the cardioprotective effects of an endothelin-A receptor blocker (ET(A)-RB) with those of an angiotensin-converting enzyme inhibitor (ACE-I) in rats with streptozotocin (STZ)-induced diabetes. EXPERIMENTAL APPROACH Diabetic rats were left untreated or received either the ET(A)-RB atrasentan or the ACE-I ramipril (each 3 mg kg(-1) per day) orally for 8 weeks. Isolated isovolumic heart function was studied during normoxia and in response to ischaemia-reperfusion. Cardiac fibrosis, tissue oxidative stress and tissue nitric oxide synthase (NOS) activity were determined. KEY RESULTS Basal left ventricular systolic contractility was lower in diabetic compared to nondiabetic hearts and ET(A)-RB or ACE-I treatment significantly antagonised the decline. Following 15 min of no-flow ischaemia, reperfusion systolic function was depressed and left-ventricular end-diastolic pressure (LVEDP) was elevated in diabetic hearts. ET(A)-RB or ACE-I treatment significantly improved recovery of reperfusion systolic and diastolic function, without differences between groups. Hydroxyproline (an index of tissue fibrosis) and malondialdehyde (a measure of tissue oxidative stress) were elevated at the end of reperfusion in diabetic, compared to nondiabetic hearts. Either treatment reduced hydroxyproline and malondialdehyde to control level. Constitutive NOS activity was similar in nondiabetic and diabetic hearts and unaffected by ET(A)-RB or ACE-I treatment. CONCLUSIONS AND IMPLICATIONS These results suggest that in experimental type 1 diabetes ET(A)-RB is as effective as an ACE-I in ameliorating myocardial functions during normoxia and ischaemia-reperfusion. Combining the two treatments neither afforded additive effects, nor diminished any protection effect seen with either drug.
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Affiliation(s)
- G Wölkart
- Department of Pharmacology and Toxicology, University of Graz Graz, Austria
| | - X Pang
- Department of Pharmacology and Toxicology, University of Graz Graz, Austria
| | - H Stessel
- Department of Pharmacology and Toxicology, University of Graz Graz, Austria
| | - M Kirchengast
- PRA International Mannheim, Germany
- Faculty of Clinical Medicine, Department of Pharmacology and Toxicology, Mannheim Ruprecht-Karls-University Heidelberg Mannheim, Germany
| | - F Brunner
- Department of Pharmacology and Toxicology, University of Graz Graz, Austria
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770
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Hwang JY, Zhang J, Kang MJ, Lee SK, Kim HA, Kim JJ, Kim JI. Hypoglycemic and hypolipidemic effects of Saururus chinensis Baill in streptozotocin-induced diabetic rats. Nutr Res Pract 2007; 1:100-4. [PMID: 20535394 PMCID: PMC2882583 DOI: 10.4162/nrp.2007.1.2.100] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Revised: 05/17/2007] [Accepted: 06/01/2007] [Indexed: 11/22/2022] Open
Abstract
Saururus chinensis Baill was reported to inhibit α-glucosidase in vitro and flatten postprandial increase in blood glucose in streptozotocin (STZ)-induced diabetic rats. We studied the effect of chronic consumption of S. chinensis Baill on blood glucose and lipid profile in STZ-induced diabetic male rats fed high fat diet. Male rats weighing 100-120 g were fed 30% fat diet with and without 10% freeze-dried leaves of S. chinensis Baill for 7 weeks after 1 week of adaptation. The rats were rendered diabetic by intravenous injection of STZ (60 mg/kg) after 6-week feeding of the assigned diets. At 1 week after the injection, the rats were sacrificed after an overnight fast. Plasma glucose (380.2 ± 14.4 mg/dL), total cholesterol (93.9 ± 7.9 mg/dL) and triglyceride levels (123.6 ± 7.5 mg/dL) of the S. chinensis Baill group were significantly lower than those of the control group (418.1 ± 12.0 mg/dL, 119.9 ± 9.4 mg/dL, 152.0 ± 10.3 mg/dL, respectively, p<0.05). Chronic consumption of S. chinesis Baill significantly decreased maltase activity of the small intestinal mucosa (120.1 ± 8.7 U/g protein) compared with the control group (96.8 ± 7.0 U/g protein, p<0.05). These results suggest that S. chinensis Baill have hypoglycemic and hypolipidemic effects by inhibiting α-glucosidase activity in the animal model of diabetes mellitus.
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Affiliation(s)
- Ji-Yeon Hwang
- Biohealth Product Research Center, School of Food and Life Science, Institute for Food Sciences, Institute of Biomedical Engineering, Inje University, Gimhae, Gyungnam 621-749, Korea
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771
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Adewole SO, Ojewole JAO. Artocarpus communis Forst. root-bark aqueous extract- and streptozotocin-induced ultrastructural and metabolic changes in hepatic tissues of Wistar rats. Afr J Tradit Complement Altern Med 2007; 4:397-410. [PMID: 20161908 PMCID: PMC2816511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Decoctions and infusions of Artocarpus communis (Forst.) (family: Moraceae) root-bark are commonly used traditionally among the Yoruba-speaking people of Western Nigeria as folk remedies for the management, control and/or treatment of an array of human diseases, including type 2, adult-onset diabetes mellitus. Although numerous bioactive flavonoids have been isolated from the roots, stem-bark and leaves of A. communis, to the best of our knowledge, the effects of the plant's root-bark extract on animal model of diabetes mellitus and on liver tissues have hitherto, not been reported in the biomedical literature. In view of this, the present study was undertaken to investigate the glycaemic effect of, and hepatic tissue ultrastructural, morphological and metabolic changes induced by A. communis root-bark aqueous extract (ACE) in Wistar rats. The ultrastructural, morphological and metabolic effects of ACE have been compared with those induced by streptozotocin (STZ) in rat experimental paradigms. Four groups (A, B, C and D) of Wistar rats, each group containing 10 rats, were used. Diabetes mellitus was induced in the diabetic groups B and C animals by intraperitoneal injections of STZ (75 mg/kg body weight), while group A rats received A. communis root-bark aqueous extract (ACE, 100 mg/kg body weight, i.p.) alone. Control group D rats received distilled water in quantities equivalent to the volume of ACE administered intraperitoneally. The rats in group C were additionally treated with ACE (100 mg/kg body weight i. p.) daily from day 3 to day 10 after STZ treatment. Hepatic glucokinase, hexokinase, glutamate dehydrogenase, succinate dehydrogenase, beta-hydroxybutyrate dehydrogenase, serum insulin and blood glucose levels of the animals were measured and recorded before and after ACE, STZ and STZ+ACE treatments. Hepatic tissues were also processed for transmission electron microscopy. Electron microscopic examinations showed toxic, deleterious alterations in the ultrastructures of groups A, B and C hepatic cells, the most prominent deleterious effects being on the hepatocytes. Ultrastructural changes observed within the hepatocytes of groups A, B and C rats include disrupted mitochondria with increase in lipid droplets, extensive hepatocellular vacuolation, scanty rough endoplasmic reticulum (RER) and ribosomes. Large glycogen clusters were also noticed displacing the mitochondria and RER in group A rats. Group A rats also developed significant hyperglycemia (p<0.05) immediately after ACE administration, while groups B and C rats developed hyperglycemia 24 hours after STZ treatment. When compared with the control group D rats, the activities of all the three subsystems were disrupted, leading to overall inhibition of oxidative phosphorylation of the liver mitochondria in groups A, B and C rats, but remain normal in the untreated group D control rats. The findings of the present study indicate that A. communis root-bark aqueous extract induces hyperglycaemia in the experimental animal model used, and that the plant's extract disrupts the ultrastructural characteristics and architecture of hepatocytes as well as oxidative energy metabolism.
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Affiliation(s)
- Stephen O Adewole
- Department of Anatomy and Cell Biology, Faculty of Basic Medical Sciences, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria
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772
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Ding H, Hashem M, Wiehler WB, Lau W, Martin J, Reid J, Triggle C. Endothelial dysfunction in the streptozotocin-induced diabetic apoE-deficient mouse. Br J Pharmacol 2005; 146:1110-8. [PMID: 16231005 PMCID: PMC1751246 DOI: 10.1038/sj.bjp.0706417] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 09/01/2005] [Accepted: 09/07/2005] [Indexed: 11/08/2022] Open
Abstract
Endothelial dysfunction plays a role in the development of atherosclerosis and diabetes-associated vascular disease and, in the streptozotocin (STZ)-induced apoE-deficient diabetic mouse, we report that, when compared to the citrate (CIT)-treated nondiabetic apoE-deficient control, acetylcholine (Ach)-mediated endothelium-dependent relaxation was reduced in the small mesenteric arteries (SMA) and the plaque-prone regions of the aorta from the STZ-diabetic mouse. In the SMA the component of Ach-mediated relaxation that was attributed to nitric oxide (NO) from STZ-treated diabetic apoE-deficient mice was enhanced; however, the endothelium-derived hyperpolarizing factor (EDHF)-mediated component was reduced. The EDHF component was assessed by determining the component of the Ach-mediated response that was resistant to the combination of the NO synthase (NOS) inhibitor Nomega-nitro-L-arginine methyl ester, cyclooxygenase inhibitor, indomethacin, and soluble guanylate cyclase inhibitor, ODQ, and inhibited by the combination of the intermediate conductance KCa (IKCa) inhibitor TRAM-34 and the small-conductance KCa (SKCa) inhibitor apamin. Endothelial NOS was increased but SK2, SK3 and connexin (Cx) 37 mRNA expressions were significantly (P<0.05) decreased in the SMA from STZ-treated apoE-deficient mice compared to the CIT-treated controls. There was no difference in the IKCa expression or in Cx 40, 43 and 45 mRNA levels between STZ- and CIT-treated mice. The microvasculature of STZ-induced apoE-deficient mice developed endothelial dysfunction, which may be linked to a decrease in the contribution of the EDHF component due to a decrease in SK2 and 3 and Cx 37 expression.
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Affiliation(s)
- Hong Ding
- School of Medical Sciences, RMIT University, Bundoora West Campus, Bundoora, Victoria 3083, Australia.
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773
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Wu Y, Ouyang JP, Wu K, Wang SS, Wen CY, Xia ZY. Rosiglitazone ameliorates abnormal expression and activity of protein tyrosine phosphatase 1B in the skeletal muscle of fat-fed, streptozotocin-treated diabetic rats. Br J Pharmacol 2005; 146:234-43. [PMID: 15997237 PMCID: PMC1576260 DOI: 10.1038/sj.bjp.0706306] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Revised: 03/31/2005] [Accepted: 04/26/2005] [Indexed: 11/09/2022] Open
Abstract
Protein tyrosine phosphatase 1B (PTP1B) acts as a physiological negative regulator of insulin signaling by dephosphorylating the activated insulin receptor (IR). Here we examine the role of PTP1B in the insulin-sensitizing action of rosiglitazone (RSG) in skeletal muscle and liver. Fat-fed, streptozotocin-treated rats (10-week-old), an animal model of type II diabetes, and age-matched, nondiabetic controls were treated with RSG (10 micromol kg(-1) day(-1)) for 2 weeks. After RSG treatment, the diabetic rats showed a significant decrease in blood glucose and improved insulin sensitivity. Diabetic rats showed significantly increased levels and activities of PTP1B in the skeletal muscle (1.6- and 2-fold, respectively) and liver (1.7- and 1.8-fold, respectively), thus diminishing insulin signaling in the target tissues. We found that the decreases in insulin-stimulated glucose uptake (55%), tyrosine phosphorylation of IRbeta-subunits (48%), and IR substrate-1 (IRS-1) (39%) in muscles of diabetic rats were normalized after RSG treatment. These effects were associated with 34 and 30% decreases in increased PTP1B levels and activities, respectively, in skeletal muscles of diabetic rats. In contrast, RSG did not affect the increased PTP1B levels and activities or the already reduced insulin-stimulated glycogen synthesis and tyrosine phosphorylation of IRbeta-subunits and IRS-2 in livers of diabetic rats. RSG treatment in normal rats did not significantly change PTP1B activities and levels or protein levels of IRbeta, IRS-1, and -2 in diabetic rats. These data suggest that RSG enhances insulin activity in skeletal muscle of diabetic rats possibly by ameliorating abnormal levels and activities of PTP1B.
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MESH Headings
- Animals
- Blotting, Western
- Diabetes Mellitus, Experimental/enzymology
- Diabetes Mellitus, Type 2/chemically induced
- Diabetes Mellitus, Type 2/metabolism
- Dietary Fats/pharmacology
- Glucose/metabolism
- Glucose Tolerance Test
- Glycogen/biosynthesis
- Hepatocytes/drug effects
- Hepatocytes/metabolism
- Hypoglycemic Agents/pharmacology
- Insulin/metabolism
- Insulin Resistance
- Liver/drug effects
- Liver/metabolism
- Liver/physiology
- Liver Glycogen/biosynthesis
- Male
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiology
- Protein Tyrosine Phosphatase, Non-Receptor Type 1
- Protein Tyrosine Phosphatases/biosynthesis
- Rats
- Rats, Sprague-Dawley
- Rosiglitazone
- Signal Transduction/drug effects
- Thiazolidinediones/pharmacology
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Affiliation(s)
- Yong Wu
- Department of Pathophysiology, Medical College of Wuhan University, Wuhan 430071, China
- Department of Physiology, Hubei College of Traditional Chinese Medicine, Wuhan 430061, China
| | - Jing Ping Ouyang
- Department of Pathophysiology, Medical College of Wuhan University, Wuhan 430071, China
| | - Ke Wu
- Department of Pathophysiology, Medical College of Wuhan University, Wuhan 430071, China
| | - Shi Shun Wang
- Department of Pathophysiology, Medical College of Wuhan University, Wuhan 430071, China
| | - Chong Yuan Wen
- Department of Endocrinopathic Sciences, People's Hospital, Wuhan University, Wuhan 430060, China
| | - Zheng Yuan Xia
- Department of Pharmacology and Therapeutics, Faculty of Medicine, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
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774
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Abstract
Transforming growth factor (TGF)-beta1 is an important fibrogenic factor that is involved in the pathogenesis of diabetic nephropathy. We evaluated the effect of circular antisense TGF-beta1 oligodeoxynucleotides (ODNs) on the TGF-beta1 expression in the rat mesangial cell culture and in streptozotocin (STZ)-induced diabetic rats. Circular antisense TGF-beta1 ODNs were found to be stable in rat serum, significantly decreasing TGF-beta1 mRNA expression compared with linear antisense ODNs in the rat mesangial cell culture. Circular antisense TGF-beta1 ODNs were introduced into the tail vein of normal rats using hemagglutinating virus of Japan (HVJ)-liposome-mediated gene transfer method and were confirmed to be delivered effectively into the kidney, liver, lungs, and spleen. To inhibit the overexpression of TGF-beta1 in diabetic kidneys, we introduced circular antisense TGF-beta1 ODNs into the STZ-induced diabetic rats. On day 13 after circular antisense TGF-beta1 ODNs injection, TGF-beta1 mRNA and protein expression markedly decreased and urinary TGF-beta1 excretion rate also dropped in the circular antisense TGF-beta1 ODNs-treated diabetic rats. These results suggest that circular antisense TGF-beta1 ODNs may be a useful tool for developing new therapeutic application for progressive diabetic nephropathy.
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Affiliation(s)
- Hyo Soon Jeong
- Department of Anatomy, Keimyung University School of Medicine, Daegu, Korea
| | - Kwan Kyu Park
- Department of Pathology, Keimyung University School of Medicine, Daegu, Korea
| | - Sang Pyo Kim
- Department of Pathology, Keimyung University School of Medicine, Daegu, Korea
| | - In Jang Choi
- Department of Anatomy, Keimyung University School of Medicine, Daegu, Korea
| | - In Kyu Lee
- Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea
| | - Hyun Chul Kim
- Kidney Institute, Keimyung University School of Medicine, Daegu, Korea
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775
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Abdouh M, Khanjari A, Abdelazziz N, Ongali B, Couture R, Hasséssian HM. Early upregulation of kinin B1 receptors in retinal microvessels of the streptozotocin-diabetic rat. Br J Pharmacol 2003; 140:33-40. [PMID: 12967932 PMCID: PMC1573993 DOI: 10.1038/sj.bjp.0705210] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
(1) Retinal microvessel responses to kinin B1 and B2 receptor agonists and antagonists were investigated in streptozotocin (STZ)-diabetic rats and age-matched controls. In addition, quantitative in vitro autoradiography was performed on retinas from control and STZ-diabetic rats with radioligands specific for B2 ([125I]HPP-Hoe 140), and B1 receptors ([125I]HPP-[des-Arg10]-Hoe 140). (2) In control rats, the B2 receptor agonist bradykinin (BK, 0.1-50 nm) vasodilated retinal vessels in a concentration and time-dependent manner. This effect was completely blocked by the B2 receptor antagonist Hoe140 (1 microm). In contrast, the B1 receptor agonist des-Arg9-BK (0.1-50 nm) was without effect. (3) Des-Arg9-BK was able to produce a concentration-dependent vasodilatation as early as 4 days after STZ injection, and the effect of 1 nm des-Arg9-BK was inhibited by the B1 receptor antagonist des-Arg10-Hoe140 (1 microm). Low-level B1 receptor binding sites were detected in control rats, but densities were 256% higher in retinas from 4- to 21-day STZ-diabetic rats. (4) In control rats, the vasodilatation in response to 1 nm BK involved neither calcium influx nor nitric oxide (NO) as GdCl3 and l-NAME were without effect. However, the vasodilatation did involve intracellular calcium mobilization as well as products of the cyclooxygenase-2 (COX-2) pathway as 2,5-di-t-butylhydroquinone (BHQ), cADP ribose and l-745 337 inhibited this response. The vasodilatation response was blocked by trans-2-phenyl cyclopropylamine (TPC) demonstrating that prostacyclins mediate this response. (5) In STZ-diabetic rats, the vasodilatation in response to des-Arg9-BK involved both calcium influx and intracellular calcium mobilization from stores both IP3 sensitive and non-IP3 sensitive. Indeed, the effect was blocked by GdCl3, BHQ and cADP ribose. Furthermore, NO production and products of the COX-2 pathway including prostacyclin are involved as the response was inhibited by l-NAME, l-745 377 and TPC. (6) Vasodilatation in response to either 1 nm BK or 1 nm des-Arg9-BK were blocked by NF023 demonstrating that a Go/Gi G-protein transduces both these effects. (7) This is the first report on the retinal circulation which provides evidence for vasodilator B2 receptors and the upregulation of B1 receptors very early following induction of diabetes with STZ rats. These results suggest that kinin receptors may be potential targets for therapeutics to treat retinopathies.
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Affiliation(s)
- Mohamed Abdouh
- Guy-Bernier Research Centre, Maisonneuve-Rosemont Hospital, Montréal, PQ Canada H1T 2M4
- Departments of Ophthalmology
| | - Ashraf Khanjari
- Guy-Bernier Research Centre, Maisonneuve-Rosemont Hospital, Montréal, PQ Canada H1T 2M4
- Biomedical Sciences
| | - Nadia Abdelazziz
- Guy-Bernier Research Centre, Maisonneuve-Rosemont Hospital, Montréal, PQ Canada H1T 2M4
- Departments of Ophthalmology
| | - Brice Ongali
- Physiology, Université de Montréal, Montréal, PQ Canada H3C 3J7
| | - Réjean Couture
- Physiology, Université de Montréal, Montréal, PQ Canada H3C 3J7
| | - Haroutioun M Hasséssian
- Guy-Bernier Research Centre, Maisonneuve-Rosemont Hospital, Montréal, PQ Canada H1T 2M4
- Departments of Ophthalmology
- Biomedical Sciences
- Author for correspondence:
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776
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Maksimovic-Ivanic D, Trajkovic V, Miljkovic DJ, Mostarica Stojkovic M, Stosic-Grujicic S. Down-regulation of multiple low dose streptozotocin-induced diabetes by mycophenolate mofetil. Clin Exp Immunol 2002; 129:214-23. [PMID: 12165076 PMCID: PMC1906457 DOI: 10.1046/j.1365-2249.2002.02001.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The new immunosuppressive agent mycophenolate mofetil (MMF) has been shown recently to exert a protective effects in certain animal models of autoimmunity, including diabetes in diabetes-prone bio-breeding (BB) rats. In the present study, the immunomodulatory potential of MMF was investigated in autoimmune diabetes induced by multiple low doses of streptozotocin (MLD-STZ) in genetically susceptible DA rats 20 mg STZ/kg body weight (b.w.) for 5 days] and CBA/H mice (40 mg STZ/kg b.w. for 5 days). In both species, short time treatment of animals with MMF (25 mg/kg) during the early development of the disease, as well as continuous MMF treatment, prevented the appearance of hyperglycaemia and inflammatory infiltrates in the pancreatic tissue. Moreover, clinical manifestations of diabetes were suppressed by application of the drug after the onset of clinical symptoms. Treatment with guanosine (1 mg/kg) in parallel with MMF completely reversed MMF activity in vivo, indicating that inhibition of inosine monophosphate dehydrogenase (IMPDH) was responsible for the observed suppressive effects. MMF-mediated protection from diabetes correlated with reduced ex vivo spontaneous spleen mononuclear cell (MNC) proliferation and defective adhesive cell interactions. MMF-treated animals also had lower local production of IFN-gamma, as well as IL-12 and nitric oxide (NO) production by peripheral tissues (spleen and peritoneal cells), compared to that in control diabetic groups, while IL-10 level was elevated. Together, these data demonstrate that MMF interferes with autoimmune process in streptozotocin-induced diabetes at multiple levels, including lymphocyte proliferation and adhesion, as well as pro/anti-inflammatory cytokine balance.
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777
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Abstract
1. The purpose of this investigation was to determine whether enhanced contractile responses to noradrenaline (NA) of mesenteric arteries from rats with chronic streptozotocin-induced diabetes are associated with increases in mean cytosolic [Ca(2+)]i. 2. [Ca(2+)]i was measured with fura 2-AM, and was monitored simultaneously with tension in perfused endothelium-denuded mesenteric arterial rings from 12 - 14 week diabetic rats and age- and gender-matched control rats. 3. Basal [Ca(2+)]i (expressed as R(n), the normalized fura 2 ratio) was not significantly different in arteries from control and diabetic rats. Similarly, no differences between control and diabetic arteries in the tension or [Ca(2+)]i responses to 80 mM KCl in the presence of phentolamine were detected. 4. The rate of tension development, peak tension and integrated tension in response to 30 microM NA were all significantly greater in diabetic than control arteries. However, this was not associated with enhancement of the corresponding [Ca(2+)]i responses in the diabetic arteries. 5. Peak contractile responses to perfusion with both 0.3 and 3 microM NA, but peak [Ca(2+)]i only in response to 0.3 microM NA, were significantly greater in diabetic than control arteries. 6. NA (30 microM) produced a greater increase in both peak tension and [Ca(2+)]i in diabetic than control arteries perfused with Ca(2+)-free solution containing 1 mM EGTA. Neither the rate nor the magnitude of NA-induced Ca(2+) influx appeared to be altered in the diabetic arteries. 7. The enhanced sustained contractile response of diabetic arteries to NA appears to be dissociated from increases in [Ca(2+)]i, and may be due to other factors, such as an increase in the Ca(2+) sensitivity of the contractile proteins.
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Affiliation(s)
- Wing Lim Chow
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, B.C., Canada V6T 1Z3
| | - Lili Zhang
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, B.C., Canada V6T 1Z3
| | - Kathleen M MacLeod
- Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, B.C., Canada V6T 1Z3
- Author for correspondence: .
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778
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Kobayashi T, Matsumoto T, Kamata K. Mechanisms underlying the chronic pravastatin treatment-induced improvement in the impaired endothelium-dependent aortic relaxation seen in streptozotocin-induced diabetic rats. Br J Pharmacol 2000; 131:231-8. [PMID: 10991915 PMCID: PMC1572325 DOI: 10.1038/sj.bjp.0703572] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. We investigated the effects of chronic pravastatin treatment on the impaired endothelium-dependent relaxation seen in aortae from established streptozotocin (STZ)-induced diabetic rats. Starting at 6 weeks of diabetes, pravastatin (10 mg kg(-1)) was administered to STZ-induced diabetic rats for 4 weeks. 2. The increased total cholesterol and low-density lipoprotein (LDL) cholesterol levels seen in STZ-induced diabetic rats were not restored to normal by pravastatin. Aortae from pravastatin-treated diabetic rats did not show an impaired endothelium-dependent relaxation to acetylcholine. The expression of the mRNA for endothelial nitric oxide synthase was unaffected by diabetes or pravastatin. 3. The enhanced level of malondialdehyde (MDA)-modified LDL seen in STZ-induced diabetic rats was normalized by pravastatin treatment. The resistance of LDL to oxidation was assessed by measuring the amount of MDA or conjugated dienes generated by incubation with copper ions. LDL isolated from diabetic rats, but not those from pravastatin-treated diabetics, showed enhanced the susceptibility to oxidation, but incubation in vitro with pravastatin had no effect on LDL oxidation. 4. Following incubation of control aortae for 6 h with LDL (0.1 mg protein ml(-1)) isolated from diabetic rats, the endothelium-dependent relaxation to acetylcholine or A23187 was impaired, but LDL isolated from control or pravastatin-treated rats had no such effect. This inhibitory effect of diabetic LDL was prevented by superoxide dismutase (SOD), a superoxide scavenger. 5. These results suggest that pravastatin preserves endothelial function in aortae from STZ-induced diabetic rats without lowering plasma cholesterol, and its effect may be due to decreased LDL oxidation.
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Affiliation(s)
- Tsuneo Kobayashi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Takayuki Matsumoto
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
| | - Katsuo Kamata
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
- Author for correspondence:
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779
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Makino A, Ohuchi K, Kamata K. Mechanisms underlying the attenuation of endothelium-dependent vasodilatation in the mesenteric arterial bed of the streptozotocin-induced diabetic rat. Br J Pharmacol 2000; 130:549-56. [PMID: 10821782 PMCID: PMC1572112 DOI: 10.1038/sj.bjp.0703354] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Experiments were designed to investigate the mechanisms underlying the diabetes-related impairment of the vasodilatations of the perfused mesenteric arterial bed induced by acetylcholine (ACh) and K(+). In streptozotocin (STZ)-diabetic rats, the ACh-induced endothelium-dependent vasodilatation was attenuated. The dose-response curves for ACh in control and diabetic rats were each shifted to the right by N(G)-nitro-L-arginine (L-NOARG) and by isotonic high K(+) (60 mM). The ACh dose-response curves under isotonic high K(+) were not different between control and diabetic rats. We also examined the vasodilatation induced by K(+), which is a putative endothelium-derived hyperpolarizing factor (EDHF). The mesenteric vasodilatation induced by a single administration of K(+) was greatly impaired in STZ-induced diabetic rats. Treatment with charybdotoxin plus apamin abolished the ACh-induced vasodilatation but enhanced the K(+)-induced response in controls and diabetic rats. After pretreatment with ouabain plus BaCl(2), the ACh-induced vasodilatation was significantly impaired and the K(+)-induced relaxation was abolished in both control and diabetic rats. The impairment of the endothelium-dependent vasodilatation of the mesenteric arterial bed seen in STZ-induced diabetic rats may be largely due to a defective vascular response to EDHF. It is further suggested that K(+) is one of the endothelium-derived hyperpolarizing factors and that the vasodilatation response to K(+) is impaired in the mesenteric arterial bed from diabetic rats.
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Affiliation(s)
- A Makino
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan
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780
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Cellek S, Rodrigo J, Lobos E, Fernández P, Serrano J, Moncada S. Selective nitrergic neurodegeneration in diabetes mellitus - a nitric oxide-dependent phenomenon. Br J Pharmacol 1999; 128:1804-12. [PMID: 10588937 PMCID: PMC1571816 DOI: 10.1038/sj.bjp.0702981] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/1999] [Accepted: 09/30/1999] [Indexed: 12/16/2022] Open
Abstract
1. In vitro and in vivo studies have demonstrated a dysfunctional nitrergic system in diabetes mellitus, thus explaining the origin of diabetic impotence. However, the mechanism of this nitrergic defect is not understood. 2. In the penises of streptozotocin (STZ)-induced diabetic rats, here, we show by immunohistochemistry that nitrergic nerves undergo selective degeneration since the noradrenergic nerves which have an anti-erectile function in the penis remained intact. 3. Nitrergic relaxation responses in vitro and erectile responses to cavernous nerve stimulation in vivo were attenuated in these animals, whereas noradrenergic responses were enhanced. 4. Activity and protein amount of neuronal nitric oxide synthase (nNOS) were also reduced in the penile tissue of diabetic rats. 5. We, thus, hypothesized that NO in the nitrergic nerves may be involved in the nitrergic nerve damage, since only the nerves which contain neuronal NO synthase underwent degeneration. 6. We administered an inhibitor of NO synthase, N(G)-nitro-L-arginine methyl ester (L-NAME), in the drinking water of rats for up to 12 weeks following the establishment of diabetes with STZ. 7. Here we demonstrate that this compound protected the nitrergic nerves from morphological and functional impairment. Our results show that selective nitrergic degeneration in diabetes is NO-dependent and suggest that inhibition of NO synthase is neuroprotective in this condition.
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Affiliation(s)
- Selim Cellek
- The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6AU, UK
| | - José Rodrigo
- Instituto Cajal, Avd Doctor Arce, No:24, Madrid 28002, Spain
| | - Edgar Lobos
- The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6AU, UK
| | | | - Julia Serrano
- Instituto Cajal, Avd Doctor Arce, No:24, Madrid 28002, Spain
| | - Salvador Moncada
- The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6AU, UK
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781
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Stosic-Grujicic S, Dimitrijevic M, Bartlett R. Leflunomide protects mice from multiple low dose streptozotocin (MLD-SZ)-induced insulitis and diabetes. Clin Exp Immunol 1999; 117:44-50. [PMID: 10403914 PMCID: PMC1905462 DOI: 10.1046/j.1365-2249.1999.00900.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/1999] [Indexed: 11/20/2022] Open
Abstract
In certain animal models of autoimmunity the isoxasol derivative leflunomide has been reported to exert a protective effect against autodestruction. In the present study, the immunomodulatory potential of the main metabolite of leflunomide, A77 1726, in experimentally induced autoimmune diabetes was investigated. The disease was induced in genetically susceptible CBA/H mice by multiple low doses of streptozotocin (MLD-SZ, 40 mg/kg per day, given intraperitoneally for 5 consecutive days). Effects of leflunomide were evaluated by two treatment protocols: mice treated with MLD-SZ were injected intraperitoneally with A77 1726 for 10 consecutive days, either during the first 10 days of the disease (early treatment), or starting from day 10 after disease induction (late treatment). Disease manifestations defined by hyperglycaemia, mononuclear infiltration into pancreas, expression of interferon-gamma (IFN-gamma) and inducible nitric oxide synthase (iNOS) and destruction of the islets of Langerhans were reduced in a dose-dependent fashion after early treatment with A77 1726 (dose range of 5-35 mg/kg per day). Moreover, late treatment with the high dose of the drug (25 mg/kg per day), started when the autoimmune disease was already apparent, arrested progression of ongoing inflammatory response. Analysis of the effects of A77 1726 on the adhesive interactions of spleen-derived or peripheral blood-derived mononuclear cells from MLD-SZ-treated and normal mice demonstrated that the drug inhibits both ex vivo and in vitro spontaneous mononuclear cell aggregation, thus suggesting that an important component of leflunomide's immunomodulatory action is suppression of adhesive interactions. These results demonstrate both preventive and therapeutic effects of leflunomide in a model of MLD-SZ-induced diabetes and suggest that the drug may be considered a potent therapeutic tool for autoimmune inflammatory disorders, including diabetes.
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Affiliation(s)
- S Stosic-Grujicic
- Institute for Biological Research 'Sinisa Stankovic', Department of Microbiology and Immunology, University School of Pharmacy, Belgrade, Yugoslavia
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782
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Abstract
OBJECTIVES This study examined the effect of cilostazol, a potent phosphodiesterase inhibitor, on the progression of neuropathies associated with streptozotocin-induced diabetes mellitus in Sprague-Dawley rats. METHODS Eight weeks after streptozotocin treatment, a pelleted diet containing 0.03% cilostazol (15 mg/kg body weight) was given for four weeks. Body weight, blood glucose level, motor nerve conduction velocity (MNCV), myelinated fiber density and size distribution of sciatic nerves were compared between age-matched normal rats (Group 1), control diabetic rats (Group 2) and cilostazol-treated diabetic rats (Group 3). RESULTS Body weight was significantly reduced and blood glucose level was significantly increased in diabetic rats (Group 2 and 3) compared to normal rats. MNCV and cAMP content of sciatic nerves were significantly reduced in diabetic rats 12 weeks after streptozotocin treatment. Myelinated fiber size and density were also significantly reduced, and thickening of the capillary walls and duplication of the basement membranes of the endoneural vessels were observed in the diabetic rats. Whereas both body weight and blood glucose level of Group 3 did not differ significantly from those of Group 2, cilostazol treatment significantly increased MNCV and cAMP content of sciatic nerves in Group 3 but not to the levels observed in Group 1. MNCV positively correlated with cAMP content of sciatic nerves (r = 0.86; p < 0.001). Cilostazol treatment not only restored myelinated fiber density and size distribution but reversed some of the vascular abnormalities. CONCLUSION These findings suggest that a reduced cAMP content in motor nerves may be involved in the development of diabetic neuropathy, and that cilostazol may prevent the progression of diabetic neuropathy by restoring functional impairment and morphological changes of peripheral nerves.
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Affiliation(s)
- K S Suh
- Department of Internal Medicine, Kyung Hee University School of Medicine, Seoul, Korea
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783
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Kobayashi T, Kamata K. Effect of insulin treatment on smooth muscle contractility and endothelium-dependent relaxation in rat aortae from established STZ-induced diabetes. Br J Pharmacol 1999; 127:835-42. [PMID: 10433489 PMCID: PMC1566078 DOI: 10.1038/sj.bjp.0702554] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. This study involved the chronic administration of low or high insulin to rats with established streptozotocin (STZ)-induced diabetes. We studied the effect of such treatment on smooth muscle contractility and endothelium-dependent relaxation using aortic strips. 2. Aortae from diabetic rats, but not those from high-insulin-treated diabetic rats, showed an impaired endothelium-dependent in response to acetylcholine (ACh) by comparison with untreated controls. 3. Isotonic high K+-induced contractility was impaired in diabetic aortae. This impairment was prevented by high-insulin treatment. 4. Noradrenaline (NA)-induced contractility was enhanced in aortae from high-insulin-treated diabetic rats, but not in those from untreated diabetic or low-insulin treated diabetic rats. 5. In the combined presence of the nitric oxide inhibitor N(G)-nitro-L-arginine and the cyclo-oxygenase inhibitor indomethacin, NA-induced contractility was significantly greater in aortae from high-insulin-treated diabetic rats than in those from controls or untreated diabetic rats. 6. An increased expression of the mRNA for the alpha1D and alpha1B adrenergic receptors was found in aortae from high-insulin-treated diabetic rats. 7. These results demonstrate that in rats with established STZ-induced diabetes, high-insulin treatment prevents the development of an impaired endothelium-dependent relaxation in the aorta, and that such treatment enhances NA-induced contractility. This enhancement may be related to an upregulation in the expression of the mRNA for the alpha1B or alpha1D adrenergic receptor that is secondary to the hyperinsulinaemia.
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MESH Headings
- Acetylcholine/pharmacology
- Animals
- Aorta/drug effects
- Aorta/physiology
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/physiopathology
- Endothelium, Vascular/physiology
- Insulin/pharmacology
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Nitroprusside/pharmacology
- Potassium/pharmacology
- RNA, Messenger/analysis
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/genetics
- Streptozocin
- Systole/drug effects
- Vasoconstriction/drug effects
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Affiliation(s)
- T Kobayashi
- Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Tokyo, Japan
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784
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Tashima K, Korolkiewicz R, Kubomi M, Takeuchi K. Increased susceptibility of gastric mucosa to ulcerogenic stimulation in diabetic rats--role of capsaicin-sensitive sensory neurons. Br J Pharmacol 1998; 124:1395-402. [PMID: 9723950 PMCID: PMC1565532 DOI: 10.1038/sj.bjp.0701974] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. We examined the gastric mucosal blood flow (GMBF) and ulcerogenic responses following barrier disruption induced by sodium taurocholate (TC) in diabetic rats and investigated the role of capsaicin-sensitive sensory neurons in these responses. 2. Animals were injected streptozotocin (STZ: 70 mg kg(-1), i.p.) and used after 5, 10 and 15 weeks of diabetes with blood glucose levels of > 350 mg dl(-1). The stomach was mounted on an ex-vivo chamber under urethane anaesthesia and exposed to 20 mM TC plus 50 mM HCl for 30 min in the presence of omeprazole. Gastric transmucosal potential difference (PD), GMBF, and luminal acid loss (H+ back-diffusion) were measured before and after exposure to 20 mM TC, and the mucosa was examined for lesions 90 min after TC treatment. 3. Mucosal application of TC caused PD reduction in all groups; the degree of PD reduction was similar between normal and diabetic rats, although basal PD values were lower in diabetic rats. In normal rats, TC treatment caused luminal acid loss, followed by an increase of GMBF, resulting in minimal damage in the mucosa. 4. The increased GMBF responses associated with H+ back-diffusion were mitigated in STZ-treated rats, depending on the duration of diabetes, and severe haemorrhagic lesions occurred in the stomach after 10 weeks of diabetes. 5. Intragastric application of capsaicin increased GMBF in normal rats, but such responses were mitigated in STZ diabetic rats. The amount of CGRP released in the isolated stomach in response to capsaicin was significantly lower in diabetic rats when compared to controls. 6. The deleterious influences on GMBF and mucosal ulcerogenic responses in STZ-diabetic rats were partially but significantly antagonized by daily insulin (4 units rat(-1)) treatment. 7. These results suggest that the gastric mucosa of diabetic rats is more vulnerable to acid injury following barrier disruption, and this change is insulin-sensitive and may be partly accounted for by the impairment of GMBF response associated with acid back-diffusion and mediated by capsaicin-sensitive sensory neurons.
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Affiliation(s)
- K Tashima
- Department of Pharmacology & Experimental Therapeutics, Kyoto Pharmaceutical University, Yamashina, Japan
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785
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Abstract
Multiple low-dose streptozotocin (MD-STZ) is widely used for the experimental induction of diabetes, but, as non-obese diabetic (NOD)-scid/scid mice have been found to display enhanced susceptibility to MD-STZ, whether or not the model is genuinely autoimmune and T cell-mediated has been unclear. Mice bearing a targeted mutation of the T cell receptor (TCR) alpha-chain were therefore used to assess whether TCR alphabeta+ cells are involved in the diabetogenic effects of MD-STZ injections. Young NOD mice lacking TCR alphabeta cells, when given five daily injections of 40 mg/kg STZ, developed diabetes at low frequency (2/12), despite the widespread destruction of pancreatic islet cells. By comparison, most normal control mice became hyperglycaemic (12/23). We conclude that whilst much of the tissue destruction observed in this model is due to the direct toxic effect of STZ, a significant amount is also due to the action of TCR alphabeta cells tipping the balance between tolerable and clinically damaging action on islet cells.
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MESH Headings
- Animals
- Diabetes Mellitus, Experimental/immunology
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Type 1/immunology
- Diabetes Mellitus, Type 1/pathology
- Female
- Hyperglycemia/chemically induced
- Hyperglycemia/immunology
- Islets of Langerhans/drug effects
- Islets of Langerhans/pathology
- Male
- Mice
- Mice, Inbred NOD
- Mice, Mutant Strains
- Pancreas/drug effects
- Pancreas/immunology
- Pancreas/pathology
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Streptozocin/pharmacology
- T-Lymphocytes/immunology
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Affiliation(s)
- J I Elliott
- Transplantation Biology Group, Clinical Sciences Centre, Hammersmith Hospital, London, UK
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786
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Abstract
1. The function of inhibitory neuronal M2 muscarinic receptors in diabetic rat lungs was investigated. 2. Neuronal M2 muscarinic receptors inhibit acetylcholine release from parasympathetic nerves. Thus, stimulation of neuronal M2 muscarinic receptors with muscarinic agonists, such as pilocarpine, inhibits acetylcholine release and vagally induced bronchoconstriction. In contrast, blockade of neuronal M2 muscarinic receptors with selective M2 muscarinic antagonists, such as AF-DX 116, potentiates acetylcholine release and vagally induced bronchoconstriction. 3. Rats were made diabetic by streptozotocin (65 mg kg (-1), i.v.). After 7 14 days the rats were anaesthetized with urethane (1.5 g kg (-1), i.p.), tracheostomized, vagotomized, ventilated and paralysed with suxamethonium (30 mg kg (-1), i.v.). Some 7 day diabetic rats were treated with low doses of long acting (NPH) insulin (2 units day (-1), s.c.) for 7 days before experimentation. This dose of insulin was not sufficient to restore normoglycaemia in diabetic rats. Thus, insulin-treated diabetic rats remained hyperglycaemic. 4. Distal electrical stimulation (5 70 Hz, 6 s, 40 V, 0.4 ms) of the vagi caused bronchoconstriction, measured as an increase in inflation pressure and bradycardia. In diabetic rats, vagally induced bronchoconstriction was significantly depressed vs controls. In contrast, bronchoconstriction caused by i.v. acetylcholine was similar in diabetic and control animals. 5. The function of neuronal M2 muscarinic receptors was tested with the muscarinic agonist pilocarpine (0.001-100.0 microg kg (-1), i.v.) and the antagonist AF-DX 116 (0.01-3.0 mg kg (-1), i.v.). Pilocarpine inhibited vagally-induced bronchoconstriction (30 Hz, 20-40 V, 0.4 ms at 6 s) and AF-DX 116 potentiated vagally-induced bronchoconstriction (20 Hz, 20-40 V, 0.4 ms at 6 s) to a significantly greater degree in diabetic rats compared to controls. 6. Both frequency-dependent vagally-induced bronchoconstriction and M2 muscarinic receptor function could be restored to nearly control values in diabetic rats treated with low doses of insulin. 7. Displacement of [3H]QNB (1 nM) with the agonist carbachol (10.0 nM-10.0 mM) from diabetic cardiac M2 muscarinic receptors revealed a half log increase in agonist binding affinity at both the high and low affinity binding sites vs controls. In contrast, M2 receptors from insulin-treated diabetic rat hearts showed no significant difference in binding affinity vs controls. 8. These data show that neuronal M2 muscarinic receptors in the lungs have increased function in diabetic rats, suggesting that insulin modulates M2 muscarinic receptor function.
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Affiliation(s)
- K E Belmonte
- Department of Environmental Health Sciences, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland 21205, USA
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787
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Abstract
Syrian hamsters of the APA strain (APA hamsters) develop spontaneous mesangial thickening in the renal glomeruli from an early age. They also develop focal and segmental glomerulosclerosis (FSG) at and after 6 months of age. In this study, histopathological, immunohistochemical and lectin histochemical examinations were conducted to clarify the modification of the spontaneous renal lesions of APA hamsters by streptozotocin(SZ)-induced diabetes. Histopathological analysis revealed that the expansion of the mesangial region was more prominent and the thickening of the glomerular basement membrane (GBM) was weaker in SZ-treated animals than in non-treated ones. Immunohistochemical analysis suggested that type IV collagen and laminin were involved in the expansion of the mesangial region and thickening of the GBM. In lectin histochemical analysis, podocytes, capillary endothelial cells, GBM and a part of mesangial region of SZ-treated animals were positive for RCA120 and GSL-I with neuraminidase-pretreatment although they were negative for these lectins in non-treated animals. These results suggest that the spontaneous glomerular lesion of APA hamsters is modified qualitatively and quantitatively by SZ-induced diabetes.
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Affiliation(s)
- E Nishida
- Laboratory of Biomedical Science, Faculty of Agriculture, University of Tokyo, Japan
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788
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Dewhurst M, Omawari N, Tomlinson DR. Aminoguanidine--effects on endoneurial vasoactive nitric oxide and on motor nerve conduction velocity in control and streptozotocin-diabetic rats. Br J Pharmacol 1997; 120:593-8. [PMID: 9051296 PMCID: PMC1564506 DOI: 10.1038/sj.bjp.0700946] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. The effects of aminoguanidine (AG) treatment on reductions in motor nerve conduction velocity (MNCV) and sciatic nerve blood flow, indexed by laser Doppler flux (LDF), were investigated in rats with experimental diabetes (streptozotocin-induced; 8-10 weeks duration). The contribution of endoneurial vasoactive nitric oxide to the LDF of these animals was also investigated by the direct micro-injection of NG-nitro-L-arginine methyl ester (L-NAME; 1 nmol in 1 microliter), followed by L-arginine (100 nmol in 1 microliter), into the sciatic nerve endoneurium. 2. The MNCV (m s-1, mean +/- 1 s.d.) of diabetic rats (38.2 +/- 1.5) was lower (P < 0.01) than that of age-matched controls (47.2 +/- 4.2). AG treatment (50 mg kg-1 day-1, i.p.) attenuated the diabetes-induced deficits in MNCV (43.4 +/- 5.9; P < 0.01), but had no effect in controls (48.8 +/- 3.8) or, if administered via drinking water (1 gl-1), diabetics (37.4 +/- 4.1). 3. L-NAME markedly reduced the resting LDF (arbitrary units; mean +/- s.e.mean) of controls (209 +/- 13 to 120 +/- 18; P < 0.005), an effect reversed by subsequent L-arginine (to 206 +/- 27). In diabetic rats the LDF reduction following L-NAME was much smaller (111 +/- 11 to 84 +/- 6; P < 0.05), but the change with L-arginine was significantly increased (to 145 +/- 12; P < 0.001). 4. AG treatment increased the resting LDF of control (265 +/- 34) and diabetic rats (133 +/- 14 for daily injection and 119 +/- 13 for drinking water). The responses to L-NAME and L-arginine were not changed markedly by AG treatment. However, L-arginine appeared to be less effective. 5. In conclusion, these data suggest that AG treatment may affect nitric oxide production in the vasa nervorum of peripheral nerves. However, the effects of AG-treatment are not consistent with the prevention of a diabetes-associated reduction in endoneurial nitric oxide production. The mechanisms by which AG attenuates nerve conduction slowing in streptozotocin-diabetic rats therefore remain unclear.
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Affiliation(s)
- M Dewhurst
- Department of Pharmacology, St. Bartholomew's, London
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789
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Abstract
The concentrations of vitamin A (retinol) and retinyl ester in the plasma and liver of normal and diabetic rats were measured by HPLC (high-performance liquid chromatography). Diabetic rats had severe hyperglycemia, induced by a single streptozotocin injection 5 weeks prior to sampling. In the normal rats, plasma retinyl palmitate was very low, and the level was increased 10-fold by diabetes. Detailed time-course studies showed that rats became hyperglycemic within 48 h of streptozotocin injection, yet the plasma retinyl palmitate level was not elevated until some three weeks later. Severe diabetes did not significantly influence plasma retinol: however. free retinol in the liver was elevated within 10 days of initiation of the disease and continued to increase for the duration of the study. These results show that streptozotocin-induced diabetes significantly alters the concentrations of hepatic retinol and plasma retinyl ester. The biochemical mechanism(s) of this altered vitamin A homeostasis in diabetes and its possible relationship to tissue pathogenesis are not known at present.
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Affiliation(s)
- Andrew T C Tsin
- Division of Life Sciences, The University of Texas at San Antonio, San Antonio, Texas. U.S.A
| | | | - Nathan L Mata
- Division of Life Sciences, The University of Texas at San Antonio, San Antonio, Texas. U.S.A
| | - Hing-Sing Yu
- Division of Life Sciences, The University of Texas at San Antonio, San Antonio, Texas. U.S.A
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790
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Cha BY, Son HY, Min BS, Kim HJ. Morphological change in pancreatic islets, insulin binding and intracellular glucose metabolism in adipocytes of streptozotocin-induced diabetic rats. Korean J Intern Med 1987; 2:8-17. [PMID: 3154820 PMCID: PMC4534923 DOI: 10.3904/kjim.1987.2.1.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
To examine the diabetogenic mechanism of streptozotocin, a histological study was performed on the pancreatic islets of male Wistar rats 7 days after an intravenous injection of streptozotocin (75 mg/kg). Furthermore, for the investigation into mechanism of insulin resistance in the insulin-dependent diabetic rats, insulin binding, glucose transport, and lipogenesis were studied in the isolated adipocytes of streptozotocin-induced diabetic rats. 1) The rate of weight gain in the control rats and the diabetic rats were 2.2 ± 1.8 g/day and −2.4 ± 2.1 g/day, respectively (p<0.05). The serum insulin levels in the control rats and the diabetic rats were 23.1 ± 10.8 μU/ml and 16.9 ± 10.6 μU/ml respectively (p<0.05). The plasma glucagon levels in the control rats and the diabetic rats were 165.7 ± 124.9 pg/ml. and 151.2 ± 78.2 pg/ml, respectively (p>0.1). 2) Microscopic examination of the pancreatic islets of the diabetic rats revealed a severe degranulation and disintegration of B cells. Electron microscopic examination showed a disruption of the intracytoplasmic organelles of B cells with complete degranulation. But the morphology of A cells was normal. 3) Maximal specific insulin binding to receptors in the adipocytes of the diabetic rats (2.10 ± 0.30%) showed an increase compared with that of the control rats (1.12 ± 0.21 %) (p<0.05). 4) Insulin receptor concentration in the adipocytes of the diabetic rats (2.33 ± 0.43 ng/0.5 × 105 cells) also showed an increase compared with that of control rats (1.03 ± 0.15 ng/0.5 × 105 cells) (p<0.05). 5) The average affinities in the adipocytes of the diabetic rats slightly decreased in the low receptor occupancy state compared with that of the control rats. 6) Basal and insulin-stimulated glucose transports in adipocytes of the diabetic rats decreased compared with that of the control rats. The maximal glucose transport in the adipocytes of the diabetic rats was 31.7% of the control value (p<0.005). 7) Basal and insulin-stimulated lipogenesis in adipocytes of the diabetic rats decreased compared with that of the control rats. The maximal lipogenesis in the adipocytes of the diabetic rats was 38.4% of the control value (p<0.005). It can be concluded that streptozotocin produces a diabetogenic mechanism in Wistar rats by directly injuring the pancreatic B cells and inducing hypoinsulinemia. The insulin resistance in the streptozotocin-induced diabetic rats results from the defects in the intracellular glucose metabolism such as glucose transport and lipogenesis.
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