Age-matched Control Rats Research Articles

Antioxidant SMe1EC2 modulates pentose phosphate pathway and glutathione-dependent enzyme activities in tissues of aged diabetic rats.

The pentose phosphate pathway and glutathione-associated metabolism are the main antioxidant cellular defense systems. This study investigated the effects of the powerful antioxidant SMe1EC2 (2-ethoxycarbonyl-8-methoxy-2,3,4,4a,5,9b-hexahydro-1H-pyrido[4,3-b] indolinium dichloride) on pentose phosphate pathway (PPP) and glutathione-dependent enzyme activities in aged diabetic and aged matched control rats. Diabetes was induced by streptozotocin injection in rats aged 13–15 months. Diabetic and control rats were divided into two subgroups, one untreated and one treated with SMe1EC2 (10 mg/kg/day, orally) for 4 months. SMe1EC2 ameliorated body weight loss, but not hyperglycemia of aged diabetic rats. Diabetes resulted in decreased glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD) and glutathione-S-transferase (GST), yet in unchanged glutathione reductase (GR) in the liver of aged diabetic rats. In the liver of the aged control rats, SMe1EC2 did not affect G6PDH, 6PGDH and GR, but it inhibited GST. SMe1EC2 also failed to affect diabetes-induced decline in 6PGDH, it ameliorated G6PDH but produced further decline in GST in the liver of aged diabetic rats. In the kidney of aged rats, G6PDH and GST were found to be comparable among the groups, but diabetes up-regulated 6PGDH and GR; these alterations were prevented by SMe1EC2. In the heart of aged diabetic rats, while GST remained unchanged, the recorded increase in G6PD, 6PGD, GR was prevented by SMe1EC2. Furthermore, an unchanged GR and remarkable increases in G6PD, 6PGD and GST were found in the lung of the aged diabetic group. These alterations were completely prevented by SMe1EC2. The results suggest that in aged rats SMe1EC2 can ameliorate the response of the kidney, heart and lung but not that of the liver against diabetes-induced glucotoxicity by interfering with the activity of redox network enzymes.

Region-dependent effects of diabetes and insulin-replacement on neuronal nitric oxide synthase- and heme oxygenase-immunoreactive submucous neurons.

AIMTo investigate the intestinal segment-specific effects of diabetes and insulin replacement on the density of different subpopulations of submucous neurons.METHODSTen weeks after the onset of type 1 diabetes samples were taken from the duodenum, ileum and colon of streptozotocin-induce diabetic, insulin-treated diabetic and sex- and age-matched control rats. Whole-mount preparations of submucous plexus were prepared from the different gut segments for quantitative fluorescent immunohistochemistry. The following double-immunostainings were performed: neuronal nitric oxide synthase (nNOS) and HuC/D, heme oxygenase (HO) 1 and peripherin, as well as HO2 and peripherin. The density of nNOS-, HO1- and HO2-immunoreactive (IR) neurons was determined as a percentage of the total number of submucous neurons.RESULTSThe total number of submucous neurons and the proportion of nNOS-, HO1- and HO2-IR subpopulations were not affected in the duodenal ganglia of control, diabetic and insulin-treated rats. While the total neuronal number did not change in either the ileum or the colon, the density of nitrergic neurons exhibited a 2- and 3-fold increase in the diabetic ileum and colon, respectively, which was further enhanced after insulin replacement. The presence of HO1- and HO2-IR submucous neurons was robust in the colon of controls (38.4%-50.8%), whereas it was significantly lower in the small intestinal segments (0.0%-4.2%, P < 0.0001). Under pathophysiological conditions the only alteration detected was an increase in the ileum and a decrease in the colon of the proportion of HO-IR neurons in insulin-treated diabetic animals.CONCLUSIONDiabetes and immediate insulin replacement induce the most pronounced region-specific alterations of nNOS-, HO1- and HO2-IR submucous neuronal density in the distal parts of the gut.

Insulin prevents aberrant mitochondrial phenotype in sensory neurons of type 1 diabetic rats

Diabetic neuropathy affects approximately 50% of diabetic patients. Down-regulation of mitochondrial gene expression and function has been reported in both human tissues and in dorsal root ganglia (DRG) from animal models of type 1 and type 2 diabetes. We hypothesized that loss of direct insulin signaling in diabetes contributes to loss of mitochondrial function in DRG neurons and to development of neuropathy. Sensory neurons obtained from age-matched adult control or streptozotocin (STZ)-induced type 1 diabetic rats were cultured with or without insulin before determining mitochondrial respiration and expression of mitochondrial respiratory chain and insulin signaling-linked proteins. For in vivo studies age-matched control rats and diabetic rats with or without trace insulin supplementation were maintained for 5months before DRG were analyzed for respiratory chain gene expression and cytochrome c oxidase activity. Insulin (10nM) significantly (P<0.05) increased phosphorylation of Akt and P70S6K by 4-fold and neurite outgrowth by 2-fold in DRG cultures derived from adult control rats. Insulin also augmented the levels of selective mitochondrial respiratory chain proteins and mitochondrial bioenergetics parameters in DRG cultures from control and diabetic rats, with spare respiratory capacity increased by up to 3-fold (P<0.05). Insulin-treated diabetic animals exhibited improved thermal sensitivity in the hind paw and had increased dermal nerve density compared to untreated diabetic rats, despite no effect on blood glucose levels. In DRG of diabetic rats there was suppressed expression of mitochondrial respiratory chain proteins and cytochrome c oxidase activity that was corrected by insulin therapy. Insulin elevates mitochondrial respiratory chain protein expression and function in sensory neurons and this is associated with enhanced neurite outgrowth and protection against indices of neuropathy.

Impaired Rhodopsin Generation in the Rat Model of Diabetic Retinopathy

Diabetic retinopathy is a common complication of diabetes mellitus. Diabetic patients experience functional deficits in dark adaptation, contrast sensitivity, and color perception before microvascular pathologies become apparent. Herein, we evaluated early changes in neural retinal function and in retinoid metabolism in the eye in diabetes. Streptozotocin-induced diabetic rats showed decreased a- and b-wave amplitudes of scotopic and photopic electroretinography responses 4 months after diabetes induction compared to nondiabetic controls. Although Western blot analysis revealed no difference in opsin expression, rhodopsin content was decreased in diabetic retinas, as shown by a difference in absorbance. Consistently, levels of 11-cis-retinal, the chromophore for visual pigments, were significantly lower in diabetic retinas compared to those in controls, suggesting a retinoid deficiency. Among visual cycle proteins, interphotoreceptor retinoid-binding protein and stimulated by retinoic acid 6 protein showed significantly lower levels in diabetic rats than those in nondiabetic controls. Similarly, serum levels of retinol-binding protein 4 and retinoids were significantly lower in diabetic rats. Overall, these results suggest that retinoid metabolism in the eye is impaired in type 1 diabetes, which leads to deficient generation of visual pigments and neural retinal dysfunction in early diabetes.

Quantitative profiling of neurotransmitter abnormalities in brain, cerebrospinal fluid, and serum of experimental diabetic encephalopathy male rat.

Diabetic encephalopathy (DE), one of the most prevalent chronic complications of diabetes mellitus, is short of effective prevention and formidable therapeutic strategies. The aim of the present study is to reveal the imbalance of tryptophan (Trp) and its metabolites in streptozotocin (STZ)-induced experimental DE rats to underscore their critical values in clinical diagnosis of the disease. For this purpose, we first developed an accurate and appropriate simultaneous method for measuring Trp and its metabolites using liquid chromatography-tandem mass spectrometry, which was in accordance with the requirements of biological sample analysis. Secondly, a single STZ intraperitoneal injection was administered to male Sprague-Dawley rats, and their cognitive function was detected by Morris water maze tests. Cerebrospinal fluid (CSF), serum, and brain tissue were then collected for the determination of Trp and its metabolites. Compared with age-matched control rats, the levels of neuroprotective serotonin decreased significantly in the samples of cortices, hippocampi, striatum, CSF, and serums in the STZ-induced DE rats, while the levels of neurotoxic 3-hydroxykynurenine increased significantly. Moreover, analogous changes of both compounds were found in the central nervous system and peripheral blood of the STZ-induced DE rats. In conclusion, we established a quantitative method for the simultaneous detection of Trp and its metabolites, and we also present a critical elucidation of the nervous system dysfunction in DE.

Nuclei-specific deposits of iron and calcium in the rat thalamus after status epilepticus revealed with quantitative susceptibility mapping (QSM).

To investigate pathological changes in the rat brain after pilocarpine-induced status epilepticus using quantitative susceptibility mapping (QSM). 3D multiecho gradient-echo (GRE) data were acquired from ex vivo brains of pilocarpine-injected and age-matched control rats at 11.7T. Maps of R2* and quantitative susceptibility were calculated from the acquired 3D GRE magnitude and phase data, respectively. QSM and R2* maps were compared with Perls' (iron) and Alizarin-red-S (calcium) stainings in the same brains to investigate the pathophysiological basis of susceptibility contrast. Bilaterally symmetric lesions were detected in reproducible thalamic regions of pilocarpine-treated rats, characterized by hyperintensity in R2* maps. In comparison, quantitative susceptibility maps demonstrated heterogeneous contrast within the lesions, with distinct hyperintense (paramagnetic) and hypointense (diamagnetic) areas. Comparison with histological assessment revealed localized deposits of iron- and calcium-positive granules in thalamic nuclei corresponding to paramagnetic and diamagnetic areas delineated in the susceptibility maps, respectively. Pronounced differences were observed in the lesions between background-corrected phase images and reconstructed susceptibility maps, indicating unreliable differentiation of iron and calcium deposits in phase maps. Multiple linear regression showed a significant association between susceptibility values and measured optical densities (ODs) of iron and calcium in the lesions (R2 = 0.42, P < 0.001), with a positive dependence on OD of iron and negative dependence on OD of calcium. QSM can detect and differentiate pathological iron and calcium deposits with high sensitivity and improved spatial accuracy compared to R2* or GRE phase images, rendering it a promising technique for diagnosing thalamic lesions after status epilepticus. 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:554-564.

MP31-14 IMBALANCE BETWEEN MATRIX ETALLOPROTEINASE-1 (MMP-1) AND TISSUE INHIBITOR OF METALLOPROTEINASE-1 (TIMP-1) CONTRIBUTES TO INCREASED FIBROSIS OF BLADDER IN LONG-TERM DIABETIC RATS

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Non-neurogenic Voiding Dysfunction I1 Apr 2017MP31-14 IMBALANCE BETWEEN MATRIX ETALLOPROTEINASE-1 (MMP-1) AND TISSUE INHIBITOR OF METALLOPROTEINASE-1 (TIMP-1) CONTRIBUTES TO INCREASED FIBROSIS OF BLADDER IN LONG-TERM DIABETIC RATS Rania Elrashidy, Zhenqun Xu, Firouz Daneshgari, and Guiming Liu Rania ElrashidyRania Elrashidy More articles by this author , Zhenqun XuZhenqun Xu More articles by this author , Firouz DaneshgariFirouz Daneshgari More articles by this author , and Guiming LiuGuiming Liu More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.968AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Diabetes induces time-dependent structural and functional alterations in the urinary bladder. We have reported the actual collagen component did not change significantly in bladder of rats in the early stage of diabetes (>9 weeks after diabetes induction), but decreased as a percentage of the total tissue. This change may be related to the increased bladder compliance in rats with diabetes. However, no data is available in the long-term effects of diabetes on bladder structure. This study aimed to characterize bladder morphology in long-term diabetic rats, and to determine the potential mechanisms. METHODS Streptozotocin was used to induce diabetes in 8 weeks old male Sprague-Dawley rats, while age-matched control rats received vehicle (citrate buffer) only. Forty-four weeks after diabetes induction, bladders were harvested for morphological and molecular biological analysis. The bladder was sectioned at the equatorial midline. Masson′s Trichrome staining was performed. The stained slides were scanned, and the images were analyzed with Image-Pro Plus 5.1 image analysis software. The expression of collagen I, elastin, transforming growth factor beta-1 (TGF-β1), matrix metalloproteinase-1 (MMP-1), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in bladder was examined by immunoblotting. For comparison between control and diabetic group, two-tailed t-test was used. A P-value less than 0.05 was considered statistically significant. RESULTS Masson′s Trichrome staining and morphometrical analysis revealed increased deposition of collagen in lamina propria and among detrusor muscle fibers in diabetic rats, compared with controls. The results from the immunoblotting demonstrated significantly higher collagen I but lower elastin expression in diabetic bladders compared with that in controls. Diabetic rats displayed a marked increase in the protein expression of TGF-β1. This was associated with imbalance of the extracellular matrix turnover markers in diabetic bladders, evidenced by downregulation of MMP-1, along with upregulation of TIMP-1. CONCLUSIONS Our study demonstrated that long-term diabetes can induce increased fibrosis in bladder in rats, likely due to the upregulation of TGF-β1 and dysregulation of MMP-1/TIMP-1 system. These changes may contribute to the bladder dysfunction in the late stage of diabetes. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e404 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Rania Elrashidy More articles by this author Zhenqun Xu More articles by this author Firouz Daneshgari More articles by this author Guiming Liu More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Cerebral small vessel disease predisposes to temporal lobe epilepsy in spontaneously hypertensive rats.

The link between cerebral small vessel disease (CSVD) and epilepsy has been poorly investigated. Some reports suggest that CSVD may predispose to temporal lobe epilepsy (TLE). Aim of this study was to evaluate whether spontaneously hypertensive rats (SHRs), an established model of systemic hypertension and CSVD, have a propensity to develop TLE more than generalized seizures. To this aim, amygdala kindling, as a model of TLE, and pentylenetetrazole (PTZ)-induced kindling, as a model of generalized seizures, have been used to ascertain whether SHRs are more prone to TLE as compared to Wistar Kyoto control rats. While young SHRs (without CSVD) do not differ from their age-matched controls in both models, old SHRs (with CSVD) develop stage 5 seizures in the amygdala kindling model (TLE) faster than age-matched control rats without CSVD. At odds, no differences between old SHRs and age-matched controls was observed in the development of PTZ kindling. Enalapril pre-treatment prevented the development of CSVD and normalized kindling development to control levels in SHRs. No difference was observed in the response to pharmacological treatment with carbamazepine or losartan. Overall, our study suggests that uncontrolled hypertension leading to CSVD might represent a risk factor for TLE. Further experimental studies are needed to unravel other risk factors that, along with CSVD, may predispose to TLE.

Vision Recovery and Connectivity by Fetal Retinal Sheet Transplantation in an Immunodeficient Retinal Degenerate Rat Model.

PurposeTo characterize a recently developed model, the retinal degenerate immunodeficient S334ter line-3 rat (SD-Foxn1 Tg(S334ter)3Lav) (RD nude rat), and to test whether transplanted rat fetal retinal sheets can elicit lost responses to light.MethodsNational Institutes of Health nude rats (SD-Foxn1 Tg) with normal retina were compared to RD nude rats with and without transplant for morphology and visual function. Retinal sheets from transgenic rats expressing human placental alkaline phosphatase (hPAP) were transplanted into the subretinal space of RD nude rats between postnatal day (P) 26 and P38. Transplant morphology was examined in vivo using optical coherence tomography (OCT). Visual function was assessed by optokinetic (OKN) testing, electroretinogram (ERG), and superior colliculus (SC) electrophysiology. Cryostat sections were analyzed for various retinal/synaptic markers and for the expression of donor hPAP.ResultsOptical coherence tomography scans showed the placement and laminar development of retinal sheet transplants in the subretinal space. Optokinetic testing demonstrated a deficit in visual acuity in RD nude rats that was improved after retinal sheet transplantation. No ERG responses were detected in the RD nude rats with or without transplantation. Superior colliculus responses were absent in age-matched control and sham surgery RD nude rats; however, robust light-evoked responses were observed in a specific location in the SC of transplanted RD nude rats. Responsive regions corresponded to the area of transplant placement in the eye. The quality of visual responses correlated with transplant organization and placement.ConclusionsThe data suggest that retinal sheet transplants integrate into the host retina of RD nude rats and recover significant visual function.

Compromised Neurotrophic and Angiogenic Regenerative Capability during Tendon Healing in a Rat Model of Type-II Diabetes.

Metabolic diseases such as diabetes mellitus type-II (DM-II) may increase the risk of suffering painful connective tissue disorders and tendon ruptures. The pathomechanisms, however, by which diabetes adversely affects connective tissue matrix metabolism and regeneration, still need better definition. Our aim was to study the effect of DM-II on expressional changes of neuro- and angiotrophic mediators and receptors in intact and healing Achilles tendon. The right Achilles tendon was transected in 5 male DM-II Goto-Kakizaki (GK) and 4 age-matched Wistar control rats. The left Achilles tendons were left intact. At week 2 post-injury, NGF, BDNF, TSP, and receptors TrkA, TrkB and Nk1 gene expression was studied by quantitative RT-PCR (qRT-PCR) and their protein distribution by immunohistochemistry in intact and injured tendons. The expression of tendon-related markers, Scleraxis (SCX) and Tenomodulin (TNMD), was evaluated by qRT-PCR in intact and injured tendons. Injured tendons of diabetic GK rats exhibited significantly down-regulated Ngf and Tsp1 mRNA and corresponding protein levels, and down-regulated Trka gene expression compared to injured Wistar controls. Intact tendons of DM-II GK rats displayed reduced mRNA levels for Ngf, Tsp1 and Trkb compared to corresponding intact non-diabetic tendons. Up-regulated Scx and Tnmd gene expression was observed in injured tendons of normal and diabetic GK rats compared to intact Wistar controls. However, these molecules were not up-regulated in injured DM-II GK rats compared to their corresponding controls. Our results suggest that DM-II has detrimental effects on neuro- and angiotrophic pathways, and such effects may reflect the compromised repair seen in diabetic Achilles tendon. Thus, novel approaches for regeneration of injured, including tendinopathic, and surgically repaired diabetic tendons may include therapeutic molecular modulation of neurotrophic pathways such as NGF and its receptors.

TRPV1 attenuates intracranial arteriole remodeling through inhibiting VSMC phenotypic modulation in hypertension.

The phenotypic modulation of contractile vascular smooth muscle cell (VSMC) is widely accepted as the pivotal process in the arterial remodeling induced by hypertension. This study aimed to investigate the potential role of transient receptor potential vanilloid type 1 (TRPV1) on regulating VSMC plasticity and intracranial arteriole remodeling in hypertension. Spontaneously hypertensive rats (SHR), Wistar-Kyoto (WKY) rats and TRPV1-/- mice on a C57BL/6J background were used. By microscopic observation of the histopathological sections of vessels from hypertensive SHR and age-matched normotensive WKY control rats, we found that hypertension induced arterial remodeling. Decreased α-smooth muscle actin (α-SMA) and SM22α while increased osteopontin (OPN) were observed in aorta and VSMCs derived from SHR compared with those in WKY, and VSMCs derived from SHR upregulated inflammatory factors. TRPV1 activation by capsaicin significantly increased expression of α-SMA and SM22α, reduced expression of OPN, retarded proliferative and migratory capacities and inhibited inflammatory status in VSMCs from SHR, which was counteracted by TRPV1 antagonist 5'-iodoresiniferatoxin (iRTX) combined with capsaicin. TRPV1 activation by capsaicin ameliorated intracranial arteriole remodeling in SHR and deoxycorticosterone acetate (DOCA)-salt hypertensive mice. However, the attenuation of arteriole remodeling by capsaicin was not observed in TRPV1-/- mice. Furthermore, TRPV1 activation significantly decreased the activity of PI3K and phosphorylation level of Akt in SHR-derived VSMCs. Taken together, we provide evidence that TRPV1 activation by capsaicin attenuates intracranial arteriole remodeling through inhibiting VSMC phenotypic modulation during hypertension, which may be at least partly attributed to the suppression PI3K/Akt signaling pathway. These findings highlight the prospect of TRPV1 in prevention and treatment of hypertension.

Functional abolition of carotid body activity restores insulin action and glucose homeostasis in rats: key roles for visceral adipose tissue and the liver.

We recently described that carotid body (CB) over-activation is involved in the aetiology of insulin resistance and arterial hypertension in animal models of the metabolic syndrome. Additionally, we have demonstrated that CB activity is increased in animal models of insulin resistance, and that carotid sinus nerve (CSN) resection prevents the development of insulin resistance and arterial hypertension induced by high-energy diets. Here, we tested whether the functional abolition of CB by CSN transection would reverse pre-established insulin resistance, dyslipidaemia, obesity, autonomic dysfunction and hypertension in animal models of the metabolic syndrome. The effect of CSN resection on insulin signalling pathways and tissue-specific glucose uptake was evaluated in skeletal muscle, adipose tissue and liver. Experiments were performed in male Wistar rats submitted to two high-energy diets: a high-fat diet, representing a model of insulin resistance, hypertension and obesity, and a high-sucrose diet, representing a lean model of insulin resistance and hypertension. Half of each group was submitted to chronic bilateral resection of the CSN. Age-matched control rats were also used. CSN resection normalised systemic sympathetic nervous system activity and reversed weight gain induced by high-energy diets. It also normalised plasma glucose and insulin levels, insulin sensitivity lipid profile, arterial pressure and endothelial function by improving glucose uptake by the liver and perienteric adipose tissue. We concluded that functional abolition of CB activity restores insulin sensitivity and glucose homeostasis by positively affecting insulin signalling pathways in visceral adipose tissue and liver.

Impaired vascular function in sepsis-surviving rats mediated by oxidative stress and Rho-Kinase pathway

We investigated long-lasting changes in endothelial and vascular function in adult rat survivors of severe sepsis induced by cecal ligation and puncture (CLP) model. For this, male Wistar rats (200–350g) had their cecum punctured once (non-transfixing hole) with a 14-gauge needle. Performed in this way, a mortality rate around 30% was achieved in the first 72h. The survivors, together with age-matched control rats (not subjected to CLP), were maintained in our holding room for 60 days (S60 group) and had the descending thoracic aorta processed for functional, histological, biochemical or molecular analyses. Endothelium-intact aortic rings obtained from sepsis-surviving S60 group displayed increased angiotensin II-induced contraction, accompanied by decreased activity of the endogenous superoxide dismutase, augmented reactive oxygen species generation, and increased levels of tyrosine nitration compared with vessels from control group. The superoxide scavengers superoxide dismutase and tempol, and the antioxidant apocynin, were able to avoid this enhanced contractility to angiotensin II in aortic rings from the S60 group. In addition, aortic rings from the S60 group presented reduced sensitivity to Y-27632, a Rho-kinase (ROCK) inhibitor. Immunoblot analyses revealed augmented RhoA and ROCK II, and high levels of phosphorylation of myosin phosphatase target subunit 1 in vessels from S60 rats. In conclusion, aortic rings from sepsis-surviving rats display endothelial dysfunction mediated by the increased production of reactive oxygen species, which in turn reduces the bioavailability of nitric oxide and increases the formation of peroxynitrite, and enhances RhoA-ROCK-mediated calcium sensitization, leading to augmented contractile responses to angiotensin II. Notably, this is the first study demonstrating long-term dysfunction in the vasculature of sepsis-surviving rats, which take place or remain beyond the acute septic insult.

Energy Deregulation Precedes Alteration in Heart Energy Balance in Young Spontaneously Hypertensive Rats: A Non Invasive In Vivo31P-MR Spectroscopy Follow-Up Study.

IntroductionGradual alterations in cardiac energy balance, as assessed by the myocardial PCr/ATP-ratio, are frequently associated with the development of cardiac disease. Despite great interest for the follow-up of myocardial PCr and ATP content, cardiac MR-spectroscopy in rat models in vivo is challenged by sensitivity issues and cross-contamination from other organs.MethodsHere we combined MR-Imaging and MR-Spectroscopy (Bruker BioSpec 9.4T) to follow-up for the first time in vivo the cardiac energy balance in the SHR, a genetic rat model of cardiac hypertrophy known to develop early disturbances in cytosolic calcium dynamics.ResultsWe obtained consistent 31P-spectra with high signal/noise ratio from the left ventricle in vivo by using a double-tuned (31P/1H) surface coil. Reasonable acquisition time (<3.2min) allowed assessing the PCr/ATP-ratio comparatively in SHR and age-matched control rats (WKY): i) weekly from 12 to 21 weeks of age; ii) in response to a bolus injection of the ß-adrenoreceptor agonist isoproterenol at age 21 weeks.DiscussionAlong weeks, the cardiac PCr/ATP-ratio was highly reproducible, steady and similar (2.35±0.06) in SHR and WKY, in spite of detectable ventricular hypertrophy in SHR.At the age 21 weeks, PCr/ATP dropped more markedly (-17.1%±0.8% vs. -3,5%±1.4%, P<0.001) after isoproterenol injection in SHR and recovered slowly thereafter (time constant 21.2min vs. 6.6min, P<0.05) despite similar profiles of tachycardia among rats.ConclusionThe exacerbated PCr/ATP drop under ß-adrenergic stimulation indicates a defect in cardiac energy regulation possibly due to calcium-mediated abnormalities in the SHR heart. Of note, defects in energy regulation were present before detectable abnormalities in cardiac energy balance at rest.

Mitochondrial Peroxiredoxin-3 protects against hyperglycemia induced myocardial damage in Diabetic cardiomyopathy

Mitochondrial oxidative stress has emerged as a key contributor towards the development of diabetic cardiomyopathy. Peroxiredoxin-3 (Prx-3), a mitochondrial antioxidant, scavenges H2O2 and offers protection against ROS related pathologies. We observed a decrease in the expression of Prx-3 in the hearts of streptozotocin (STZ) induced diabetic rats, and also high glucose treated H9c2 cardiac cells, which may augment oxidative stress mediated damage. Hence we hypothesized that overexpression of Prx-3 could prevent the cardiac damage associated with diabetes. In this study we used quercetin (QUE) to achieve Prx-3 induction in vivo, while a Prx-3 overexpressing H9c2 cell line was employed for carrying out in vitro studies. Diabetes was induced in Wistar rats by a single intraperitoneal injection of STZ. Quercetin (50mg/kg body weight) was delivered orally to hyperglycemic and age matched control rats for 2 months. Quercetin treatment induced the myocardial expression of Prx-3 but not Prx-5 both in control and STZ rats. Prx-3 induction by quercetin prevented diabetes induced oxidative stress as confirmed by decrease in expression of markers such as 4-HNE and mitochondrial uncoupling protein, UCP-3. It was also successful in reducing cardiac cell apoptosis, hypertrophy and fibrosis leading to amelioration of cardiac contractility defects. Overexpression of Prx-3 in cultured H9c2 cardiac cells could significantly diminish high glucose inflicted mitochondrial oxidative damage and apoptosis, thus strengthening our hypothesis. These results suggest that diabetes induced cardiomyopathy can be prevented by elevating Prx-3 levels thereby providing extensive protection to the diabetic heart.

Reversal of diabetes-induced behavioral and neurochemical deficits by cinnamaldehyde

BackgroundChronic hyperglycemia during diabetes is associated with altered cognitive function. Cinnamaldehyde showed to have many pharmacological activities indicating anti-diabetic, cognitive enhancer, antiinflammatory etc. In the present study, we have investigated the effects of cinnamaldehyde (CA) on diabetes-induced cognitive deficits. MethodsDiabetes was induced in Sprague Dawley rats using high fat diet followed by streptozotocin (35mg/kg, i.p.). High fat diet feeding was continued for 18 week after STZ administration. CA was administered daily during the last 3 weeks (week 16–18) at a doses of 10, 20 and 40mg/kg (p.o.). Animals were subjected to behavioral tests during 18th week. Neurotransmitter levels (glutamate and GABA), acetylcholine esterase (AChE) activity and inflammatory markers (TNF-α and IL-6) were assessed in the hippocampus and cortex. ResultsVehicle-treated diabetic rats showed impaired behavior in open field, elevated plus maze and water maze test compared to age-matched control rats. Cinnamaldehyde showed significant reduction in blood glucose levels at dose of 20 and 40mg/kg. Three weeks treatments of cinnamaldehyde showed significant amelioration of behavioral deficits in diabetic rats. Chronic treatment with cinnamaldehyde showed improvement in brain ChE activity, neurotransmitter levels and reduction in IL-6 and TNF-α levels. ConclusionThe present study demonstrates that treatment with cinnamaldehyde reverse neuroinflammation and changes in neurotransmitter levels, and consequently improves behavioral deficits in diabetic rats.

Prolonged Consumption of Sucrose in a Binge-Like Manner, Alters the Morphology of Medium Spiny Neurons in the Nucleus Accumbens Shell.

The modern diet has become highly sweetened, resulting in unprecedented levels of sugar consumption, particularly among adolescents. While chronic long-term sugar intake is known to contribute to the development of metabolic disorders including obesity and type II diabetes, little is known regarding the direct consequences of long-term, binge-like sugar consumption on the brain. Because sugar can cause the release of dopamine in the nucleus accumbens (NAc) similarly to drugs of abuse, we investigated changes in the morphology of neurons in this brain region following short- (4 weeks) and long-term (12 weeks) binge-like sucrose consumption using an intermittent two-bottle choice paradigm. We used Golgi-Cox staining to impregnate medium spiny neurons (MSNs) from the NAc core and shell of short- and long-term sucrose consuming rats and compared these to age-matched water controls. We show that prolonged binge-like sucrose consumption significantly decreased the total dendritic length of NAc shell MSNs compared to age-matched control rats. We also found that the restructuring of these neurons resulted primarily from reduced distal dendritic complexity. Conversely, we observed increased spine densities at the distal branch orders of NAc shell MSNs from long-term sucrose consuming rats. Combined, these results highlight the neuronal effects of prolonged binge-like intake of sucrose on NAc shell MSN morphology.

Intermittent hypoxia maintains glycemia in streptozotocin-induced diabetic rats.

Increasing studies have shown protective effects of intermittent hypoxia on brain injury and heart ischemia. However, the effect of intermittent hypoxia on blood glucose metabolism, especially in diabetic conditions, is rarely observed. The aim of this study was to investigate whether intermittent hypoxia influences blood glucose metabolism in type 1 diabetic rats. Streptozotocin-induced diabetic adult rats and age-matched control rats were treated with intermittent hypoxia (at an altitude of 3 km, 4 h per day for 3 weeks) or normoxia as control. Fasting blood glucose, body weight, plasma fructosamine, plasma insulin, homeostasis model assessment of insulin resistance (HOMA-IR), pancreas β-cell mass, and hepatic and soleus glycogen were measured. Compared with diabetic rats before treatment, the level of fasting blood glucose in diabetic rats after normoxic treatment was increased (19.88 ± 5.69 mmol/L vs. 14.79 ± 5.84 mmol/L, p < 0.05), while it was not different in diabetic rats after hypoxic treatment (13.14 ± 5.77 mmol/L vs. 14.79 ± 5.84 mmol/L, p > 0.05). Meanwhile, fasting blood glucose in diabetic rats after hypoxic treatment was also lower than that in diabetic rats after normoxic treatment (13.14 ± 5.77 mmol/L vs. 19.88 ± 5.69 mmol/L, p<0.05). Plasma fructosamine in diabetic rats receiving intermittent hypoxia was significantly lower than that in diabetic rats receiving normoxia (1.28 ± 0.11 vs. 1.39 ± 0.11, p < 0.05), while there were no significant changes in body weight, plasma insulin and β-cell mass. HOMA-IR in diabetic rats after hypoxic treatment was also lower compared with diabetic rats after normoxic treatment (3.48 ± 0.48 vs. 3.86 ± 0.42, p < 0.05). Moreover, intermittent hypoxia showed effect on the increase of soleus glycogen but not hepatic glycogen. We conclude that intermittent hypoxia maintains glycemia in streptozotocin-induced diabetic rats and its regulation on muscular glycogenesis may play a role in the underlying mechanism.

Adolescent caffeine consumption increases adulthood anxiety-related behavior and modifies neuroendocrine signaling

Caffeine is a commonly used psychoactive substance and consumption by children and adolescents continues to rise. Here, we examine the lasting effects of adolescent caffeine consumption on anxiety-related behaviors and several neuroendocrine measures in adulthood. Adolescent male Sprague-Dawley rats consumed caffeine (0.3g/L) for 28 consecutive days from postnatal day 28 (P28) to P55. Age-matched control rats consumed water. Behavioral testing for anxiety-related behavior began in adulthood (P62) 7 days after removal of caffeine. Adolescent caffeine consumption enhanced anxiety-related behavior in an open field, social interaction test, and elevated plus maze. Similar caffeine consumption in adult rats did not alter anxiety-related behavior after caffeine removal. Characterization of neuroendocrine measures was next assessed to determine whether the changes in anxiety were associated with modifications in the HPA axis. Blood plasma levels of corticosterone (CORT) were assessed throughout the caffeine consumption procedure in adolescent rats. Adolescent caffeine consumption elevated plasma CORT 24h after initiation of caffeine consumption that normalized over the course of the 28-day consumption procedure. CORT levels were also elevated 24h after caffeine removal and remained elevated for 7 days. Despite elevated basal CORT in adult rats that consumed caffeine during adolescence, the adrenocorticotropic hormone (ACTH) and CORT response to placement on an elevated pedestal (a mild stressor) was significantly blunted. Lastly, we assessed changes in basal and stress-induced c-fos and corticotropin-releasing factor (Crf) mRNA expression in brain tissue collected at 7 days withdrawal from adolescent caffeine. Adolescent caffeine consumption increased basal c-fos mRNA in the paraventricular nucleus of the hypothalamus. Adolescent caffeine consumption had no other effects on the basal or stress-induced c-fos mRNA changes. Caffeine consumption during adolescence increased basal Crf mRNA in the central nucleus of the amygdala, but no additional effects of stress or caffeine consumption were observed in other brain regions. Together these findings suggest that adolescent caffeine consumption may increase vulnerability to psychiatric disorders including anxiety-related disorders, and this vulnerability may result from dysregulation of the neuroendocrine stress response system.

Electroacupuncture Attenuates Visceral Pain and Reverses Upregulation of TRPV1 Expression in Adult Rats with Neonatal Maternal Deprivation

Irritable bowel syndrome (IBS) is characterized by chronic visceral hypersensitivity that companied by altered bowel movement. However, the treatment options are very limited. The aim of this study was to investigate effects of electroacupuncture (EA) on visceral hypersensitivity in a rat model of IBS and to explore the underlying mechanisms of EA effects. Visceral hypersensitivity was established by neonatal maternal deprivation (NMD) in male rats on postnatal days 2 - 15. Behavioral experiments were conducted at the age of 7 weeks. Treatment with EA at Zusanli (stomach-36, ST-36) significantly reduced abdominal withdrawal reflex (AWR) scores in NMD rats but not in age-matched healthy control rats. In addition, EA treatment hyperpolarized resting membrane potentials, increased the rheobase and reduced the numbers of action potentials evoked by 2 and 3 times rheobase current stimulation of dorsal root ganglion (DRG) neurons innervating the colon. NMD markedly enhanced expression of TRPV1 in colon related DRGs while EA treatment drastically suppressed the expression of TRPV1 in DRGs of NMD rats. These data suggest that EA treatment produced an analgesic effect, which might be mediated at least in a part by suppression of TRPV1 expression and by inhibition of neuronal excitability of primary sensory neurons in rats with chronic visceral pain.