Rapid effects of insulin on in vitro translational activity of specific mRNA in diabetic rat heart

1986 ◽  
Vol 250 (5) ◽  
pp. E558-E563 ◽  
Author(s):  
R. Shanker ◽  
W. E. Neeley ◽  
W. H. Dillmann
Keyword(s):  
Molecular Mechanisms ◽  
Rapid Change ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Delayed Response ◽  
Insulin Administration ◽  
Mrna Species ◽  
Translational Activity ◽  
Specific Mrna

We studied the time course of response of specific cardiac mRNA after administration of insulin to diabetic rats. The primary aim was to identify specific cardiac mRNA, which show a rapid response to insulin administration. Diabetic rats were injected with 2 U of regular insulin intravenously, and total cardiac RNA was prepared 0.5, 1.5, 3, 5, 12, and 24 h later. RNA was translated in vitro in the presence of [35S]methionine and the translational products separated by two-dimensional electrophoresis and quantitated by digital matrix photometry. A rapid change in the translational activity of five specific mRNA species was observed within 0.5 h after administration of insulin to the diabetic animal. One translational product exhibits a more delayed response at 1.5 h. The predominance of three of these products was increased, while that of three was decreased. Two specific mRNA coding for translation products designated as spots 97 and 106 show the most significant change, with a dramatic decrease of 15-fold and 6.5-fold, respectively, within 0.5 h after insulin administration. The change in levels of these specific mRNA species could result from effects of insulin at various sites of mRNA synthesis or degradation. However, the rapidity of the response is compatible with a direct effect of insulin on gene expression. The very quick response of these specific mRNA species to insulin could thus serve as a useful model system to examine the molecular mechanisms of insulin action in the heart.

Regulation of hepatic triiodothyronine production in the streptozotocin-induced diabetic rat

1984 ◽  
Vol 247 (4) ◽  
pp. E526-E533
Author(s):  
A. S. Jennings
Keyword(s):  
Diabetic Rats ◽  
Diabetic Rat ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Insulin Administration ◽  
Progressive Decline ◽  
Serum T4 ◽  
Fasted Rats

The effect of diabetes on 3,5,3'-triiodothyronine (T3) production was determined in the isolated perfused rat liver. Induction of diabetes with streptozotocin resulted in decreased serum thyroxine (T4) and T3 levels and a progressive decline in hepatic T3 production over 5 days. The decline in T3 production resulted from decreased conversion of T4 to T3, whereas T4 uptake was unchanged. Insulin administration restored serum T4 and T3, hepatic conversion of T4 to T3, and T3 production to normal levels. When serum T4 levels in diabetic rats were maintained by T4 administration, the conversion of T4 to T3 and T3 production returned to control levels. However, restoration of serum T4 levels in fasted rats failed to correct the decrease in hepatic T4 uptake or T3 production. Glucagon, at supraphysiological concentrations in vitro and in vivo, slightly decreased T4 uptake and T3 production without altering the conversion of T4 to T3. These data suggest that the fall in serum T4 levels observed in diabetic rats is important in mediating the decreased hepatic conversion of T4 to T3 and T3 production.

Effect of diabetes and insulin treatment of diabetic rats on total RNA, poly(A)+ RNA, and mRNA in skeletal muscle

1991 ◽  
Vol 260 (3) ◽  
pp. C409-C416 ◽  
Author(s):  
J. D. Kent ◽  
S. R. Kimball ◽  
L. S. Jefferson
Keyword(s):  
Skeletal Muscle ◽  
Ribosomal Rna ◽  
Time Course ◽  
Diabetic Rats ◽  
In Vitro Translation ◽  
Specific Gene ◽  
Insulin Administration ◽  
Tissue Mass ◽  
Total Rna

We have assessed the time course of alterations in several biochemical parameters and expression of specific mRNAs in gastrocnemius muscle following both the induction of diabetes and the administration of insulin to diabetic rats. Muscle mass, total RNA, and total protein were reduced, whereas poly(A)+ RNA relative to total RNA was increased following the induction of diabetes. All the above parameters, with the exception of poly(A)+ RNA, were reciprocally and rapidly altered following administration of insulin to 3-day diabetic animals. These changes suggest that during the induction of diabetes 1) total cellular protein is reduced at a rate that is less than the reduction in gastrocnemius mass, whereas RNA is reduced at a rate 1.5 times the reduction in tissue mass, and 2) poly(A)+ RNA is elevated relative to total RNA. After insulin administration, there appears to be coordinate synthesis of both poly(A)+ RNA and ribosomal RNA, assuming 85% of total RNA is ribosomal. Therefore, we conclude that poly(A)+ RNA is more stable than ribosomal RNA during diabetes, whereas the amounts of poly(A)+ RNA and ribosomal RNA are increased at the same rates following insulin administration to diabetic animals. Analysis of expression of specific gene products over the same time course, as assessed by in vitro translation of total RNA followed by two-dimensional gel analysis, suggests that there are a few mRNAs that are very rapidly altered in response to insulin administration. The mRNAs that are altered demonstrate variable temporal patterns of either repression or full or transient expression. These rapid, but limited, alterations in gene expression may prove important in the development of the defects that occur in skeletal muscle in response to diabetes.

scholarly journals Accumulation of diabetic rat peripheral nerve myelin by macrophages increases with the presence of advanced glycosylation endproducts.

1984 ◽  
Vol 160 (1) ◽  
pp. 197-207 ◽  
Author(s):  
H Vlassara ◽  
M Brownlee ◽  
A Cerami
Keyword(s):  
Steady State ◽  
Peripheral Nerve ◽  
Diabetic Rats ◽  
Myelin Proteins ◽  
Diabetic Rat ◽  
Striking Difference ◽  
Nonenzymatic Glycosylation ◽  
Advanced Glycosylation

We have previously shown that increased nonenzymatic glycosylation occurs in peripheral nervous tissue of diabetic humans and animals, primarily on the PO-protein of peripheral nerve myelin. The pathophysiologic mechanism by which this biochemical alteration leads to myelin breakdown and removal is not as yet understood. In the present study we show that advanced glycosylation end-product (AGE) adducts that form during long-term exposure of peripheral nerve myelin proteins to glucose in vitro and in vivo markedly alter the way in which myelin interacts with elicited macrophages. In this interaction, macrophages appear to specifically recognize AGEs on myelin, since AGE-BSA competes nearly as effectively as AGE-myelin, while neither unmodified BSA nor unmodified myelin compete. The failure of yeast mannan to interfere with macrophage recognition of AGE-myelin suggests that the mannose/fucose receptor does not mediate this process. Recognition of AGE-protein by macrophages is associated with endocytosis, as demonstrated by resistance of cell-associated radioactivity to removal by trypsin action, and by low temperature inhibition of ligand accumulation in the cellular fraction. 125I-labeled myelin that had been incubated in vitro with 50 mM glucose for 8 wk reached a steady state accumulation within thioglycolate-elicited macrophages that was five times greater than that of myelin incubated without glucose. Similarly, myelin isolated from rats having diabetes for 1.5-2.0 years duration had a steady state level that was 9 times greater than that of myelin from young rats, and 3.5 times greater than that of myelin from age-matched controls. In contrast, myelin isolated from rats having diabetes for 4-5 wk had the same degree of accumulation observed with myelin of age-matched normal rats. These data suggest that the amount of increased nonenzymatic glycosylation observed in the myelin of short-term diabetic rats had not yet resulted in the significant accumulation of AGE-myelin present both in vitro and in the long-term diabetic rats. The disappearance of acid-insoluble radioactivity from within the cells and the appearance of acid-soluble radioactivity released into the medium were very similar for the two groups, suggesting that the striking difference in accumulation seen between normal myelin and AGE-myelin is due primarily to increased uptake. Formation of irreversible AGE-adducts on myelin appears to promote the recognition and uptake of the modified myelin by macrophages. This interaction between AGE-myelin and macrophages may initiate or contribute to the segmental demyelination associated with diabetes and the normal aging of peripheral nerve.

Metabolism of VLDL is increased in streptozotocin-induced diabetic rat hearts

2000 ◽  
Vol 278 (6) ◽  
pp. H1874-H1882 ◽  
Author(s):  
Nandakumar Sambandam ◽  
Mohammed A. Abrahani ◽  
Scott Craig ◽  
Osama Al-Atar ◽  
Esther Jeon ◽  
...  
Keyword(s):  
Lipolytic Activity ◽  
Isolated Heart ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Diabetic Rats ◽  
Diabetic Heart ◽  
Diabetic Rat ◽  
Rat Hearts ◽  
Heparin Plasma

In streptozotocin (STZ)-induced diabetic rats, we previously showed an increased heparin-releasable (luminal) lipoprotein lipase (LPL) activity from perfused hearts. To study the effect of this enlarged LPL pool on triglyceride (TG)-rich lipoproteins, we examined the metabolism of very-low-density lipoprotein (VLDL) perfused through control and diabetic hearts. Diabetic rats had elevated TG levels compared with control. However, fasting for 16 h abolished this difference. When the plasma lipoprotein fraction of density <1.006 g/ml from fasted control and diabetic rats was incubated in vitro with purified bovine or rat LPL, VLDL from diabetic animals was hydrolyzed as proficiently as VLDL from control animals. Post-heparin plasma lipolytic activity was comparable in control and diabetic animals. However, perfusion of control and diabetic rats with heparinase indicated that diabetic hearts had larger amounts of LPL bound to heparan sulfate proteoglycan-binding sites. [3H]VLDL obtained from control rats, when recirculated through the isolated heart, disappeared at a significantly faster rate from diabetic than from control rat hearts. This increased VLDL-TG hydrolysis was essentially abolished by prior perfusion of the diabetic heart with heparin, implicating LPL in this process. These findings suggest that the enlarged LPL pool in the diabetic heart is present at a functionally relevant location (at the capillary lumen) and is capable of hydrolyzing VLDL. This could increase the delivery of free fatty acid to the heart, and the resultant metabolic changes could induce the subsequent cardiomyopathy that is observed in the chronic diabetic rat.

Reversal of nerve damage in streptozotocin-diabetic rats by acute application of insulin in vitro

1988 ◽  
Vol 75 (6) ◽  
pp. 629-635 ◽  
Author(s):  
Geoffrey Burnstock ◽  
Rhona Mirsky ◽  
Abebech Belai
Keyword(s):  
Vasoactive Intestinal Polypeptide ◽  
Calcitonin Gene Related Peptide ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Rat Ileum ◽  
Related Peptide ◽  
Calcitonin Gene ◽  
Enteric Nerves ◽  
Intestinal Polypeptide

1. Immunohistochemical, immunoblotting and release experiments were performed on ileum from control rats, from 8-week streptozotocin-diabetic rats and from diabetic rats after acute application of insulin in vitro. 2. There was an increase in vasoactive-intestinal-polypeptide-like and a decrease in calcitonin-gene-related-peptide-like immunoreactivity in the myenteric plexus of the diabetic rat ileum, although electrically evoked release of both peptides from enteric nerves was defective. Acute application of insulin in vitro reversed the defective release and changes in immunoreactivity of vasoactive intestinal polypeptide and calcitonin-gene-related peptide seen in the enteric nerves of streptozotocin-diabetic rat ileum. 3. In addition, using a monoclonal neurofilament antibody RT 97 that recognizes a phosphorylated neurofilament epitope present in normal enteric nerves, it was shown that this phosphorylated neurofilament epitope was absent in diabetic nerves, even though a polyclonal neurofilament antibody revealed that neurofilaments were present in both axons and cell bodies of the myenteric plexus of diabetic rat ileum. After only 2 h of insulin incubation in vitro, the phosphorylated neurofilament epitope was again present in the nerves. 4. It is suggested that the abnormal distribution of phosphorylated neurofilaments and defective storage and release of vasoactive intestinal polypeptide and calcitonin-gene-related peptide in the present study may be a more general feature of diabetes. The restoration of these abnormalities by continuous acute insulin application in vitro shown here suggests that the availability of a steady level of insulin might prevent some of the changes which occur in early stages of diabetes. If so, this could influence the use of insulin in the treatment of diabetes, particularly in view of the recent report that short-term continuous subcutaneous insulin infusion restores the function of the autonomic and peripheral nerves in type I diabetic patients [Krönert, K., Hülsen, J., Luft, D., Stetter, T. & Eggstein, M. (1987) Journal of Clinical Endocrinology and Metabolism, 64, 1219–1223].

scholarly journals Effects of streptozotocin-diabetes and insulin administration in vivo or in vitro on the activities of five enzymes in the adipose-tissue triacylglycerol-synthesis pathway

1987 ◽  
Vol 243 (1) ◽  
pp. 289-292 ◽  
Author(s):  
E D Saggerson ◽  
C A Carpenter
Keyword(s):  
Insulin Treatment ◽  
Streptozotocin Diabetes ◽  
Diacylglycerol Acyltransferase ◽  
Fatty Acyl ◽  
Diabetic Rats ◽  
Insulin Administration ◽  
Triacylglycerol Synthesis ◽  
Phosphatidate Phosphohydrolase

At 2 days after administration of streptozotocin (100 mg/kg), activities in rat epididymal fat-pads of the following enzymes were significantly decreased: fatty acyl-CoA synthetase (FAS), mitochondrial and microsomal forms of glycerolphosphate acyltransferase (GPAT), monoacylglycerolphosphate acyltransferase (MGPAT) and Mg2+-dependent phosphatidate phosphohydrolase (PPH). There were no significant changes in diacylglycerol acyltransferase or Mg2+-independent PPH. Insulin administration to diabetic rats over 2 days restored activities of FAS, both forms of GPAT, MGPAT and Mg2+-dependent PPH. Significant restoration of all five activities was also seen 2 h after a single administration of insulin, but was not observed 45 min after insulin treatment. Insulin significantly increased all five enzyme activities when adipocytes from diabetic rats were incubated for 2 h with a mixture of glucose, lactate, pyruvate and amino acids.

scholarly journals Chitosan-sodium alginate-fatty acid nanocarrier composite: lutein bioavailability, absorption pharmacokinetics in diabetic rat and protection of retinal cells against H2O2 induced oxidative stress in vitro

2020 ◽  
Author(s):  
Veeresh B Toragall ◽  
Baskarn V
Keyword(s):  
Oxidative Stress ◽  
Sodium Alginate ◽  
Mitochondrial Membrane ◽  
Life Time ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Retinal Cells ◽  
Intracellular Ros ◽  
Pre Treatment

Abstract Aiming to enhance therapeutic efficiency of lutein, lutein loaded chitosan-sodium alginate (CS-SA) based nanocarrier composite (LNCs) were prepared and evaluated for lutein bioavailability and pharmacokinetics in diabetic rats in comparison to micellar lutein (control). Further, cytotoxicity, cellular uptake and protective activity against H2O2 induced oxidative stress in ARPE-19 cells were studied. Results revealed that LNCs displayed maximal lutein AUC in plasma, liver and eye respectively in normal (3.1, 2.7 and 5.2 folds) and diabetic (7.3, 3.4 and 2.8 folds) rats. Lutein from LNCs exhibited a higher half-life time, mean residence time and slow clearance from the plasma, indicating prolonged circulation compared to control. In ARPE-19 cells, pre-treatment with LNCs (10 µM) have significantly attenuated H2O2 induced cell death, intracellular ROS and mitochondrial membrane potential compared to control. In conclusion, LNCs improve the lutein bioavailability in conditions like diabetes, diabetic retinopathy and cataract to curtail oxidative stress in retinal cells.

scholarly journals HflX is a GTPase that controls hypoxia-induced replication arrest in slow-growing mycobacteria

2021 ◽  
Vol 118 (12) ◽  
pp. e2006717118
Author(s):  
Jie Yin Grace Ngan ◽  
Swathi Pasunooti ◽  
Wilford Tse ◽  
Wei Meng ◽  
So Fong Cam Ngan ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Critical Role ◽  
Chronic Phase ◽  
Replication Arrest ◽  
Translational Activity ◽  
Splitting Factor ◽  
Spleen And Lymph Nodes ◽  
Slow Growing ◽  
Tolerant State

GTPase high frequency of lysogenization X (HflX) is highly conserved in prokaryotes and acts as a ribosome-splitting factor as part of the heat shock response in Escherichia coli. Here we report that HflX produced by slow-growing Mycobacterium bovis bacillus Calmette–Guérin (BCG) is a GTPase that plays a critical role in the pathogen’s transition to a nonreplicating, drug-tolerant state in response to hypoxia. Indeed, HflX-deficient M. bovis BCG (KO) replicated markedly faster in the microaerophilic phase of a hypoxia model that resulted in premature entry into dormancy. The KO mutant displayed hallmarks of nonreplicating mycobacteria, including phenotypic drug resistance, altered morphology, low intracellular ATP levels, and overexpression of Dormancy (Dos) regulon proteins. Mice nasally infected with HflX KO mutant displayed increased bacterial burden in the lungs, spleen, and lymph nodes during the chronic phase of infection, consistent with the higher replication rate observed in vitro in microaerophilic conditions. Unlike fast growing mycobacteria, M. bovis BCG HlfX was not involved in antibiotic resistance under aerobic growth. Proteomics, pull-down, and ribo-sequencing approaches supported that mycobacterial HflX is a ribosome-binding protein that controls translational activity of the cell. With HflX fully conserved between M. bovis BCG and M. tuberculosis, our work provides further insights into the molecular mechanisms deployed by pathogenic mycobacteria to adapt to their hypoxic microenvironment.

In vivo and in vitro resistance to maximal insulin-stimulated glucose disposal in insulin deficiency

1985 ◽  
Vol 249 (3) ◽  
pp. E312-E316 ◽  
Author(s):  
E. Dall'Aglio ◽  
H. Chang ◽  
C. B. Hollenbeck ◽  
C. E. Mondon ◽  
C. Sims ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Glucose Transport ◽  
Diabetic Rats ◽  
Glucose Disposal ◽  
Diabetic Rat ◽  
Insulin Deficiency ◽  
Fat Cell ◽  
Total Body

The effect of streptozotocin-induced diabetes mellitus on maximal insulin-stimulated glucose uptake in the rat was studied in isolated adipocyte, perfused hindlimb, and the intact organism. Basal glucose transport per fat cell was reduced by approximately two-thirds (P less than 0.001), being associated with a similar decrease in glucose oxidation per fat cell (P less than 0.001). There was also a significant decrease (P less than 0.001) in basal glucose uptake by perfused hindlimb of diabetic rats of approximately 40%. Furthermore, maximal insulin-stimulated glucose transport and oxidation were approximately 50% lower (P less than 0.001) in fat cells of diabetic as compared with control rats. In contrast, maximal insulin-stimulated glucose disposal by perfused hindlimbs from diabetic and control rats was similar, and this was also true of the ability of insulin to maximally stimulate glucose uptake in the intact normal and diabetic rat. These findings indicate that variation exists in the manner in which insulin-sensitive tissues respond to experimentally induced insulin deficiency and support the view that total body glucose disposal is primarily related to insulin action on muscle.

scholarly journals Stellaria media attenuates the hyperglycemia and hyperlipidemia in alloxan-induced diabetic rat

2019 ◽  
Vol 14 (2) ◽  
pp. 80-86 ◽  
Author(s):  
Rahmat Khan ◽  
Wasim Ahmad ◽  
Mushtaq Ahmed
Keyword(s):  
Research Work ◽  
Diabetic Control ◽  
Experimental Models ◽  
Diabetic Rats ◽  
Diabetic Rat ◽  
Serum Enzyme ◽  
Stellaria Media ◽  
Diabetic Treatment

Abstract The objective of this research work was to assess the hyperglycemic and hyperlipidemiceffects of Stellaria media in alloxan induced diabetic rats using different experimental models. Standard documented protocols were used to concede the in vitro and in vivo activities. Biochemical markers studies were also done. The results of the study showed strong pancreatic α-amylase and β-glucosidase inhibition in-vitroat varying concentrations of the extract which further validated the in-vivo anti-diabetic action of the plant because of the inhibition of the above enzymes.The administration of various concentrations of the extract showedmomentous decrease in fasting blood level when compared to diabetic control. Similarly, remarkably improved hemoglobin (+20.10%), and decreased HbA1c (−48.44%) was observed when compared to diabetic control rats. The extract also caused reduced serum enzyme (ALT, ALP, bilirubin) levels and produced a succeeding recovery toward their normal values.It can be concluded from these investigations that the in-vitro and in-vivo hypoglycemic and hypolipidemic activity offers the methodicaljustification for the use of S. media in herb based anti-diabetic treatment.

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