Impaired IGF-I signalling of hypertrophic hearts in the developmental phase of hypertension in genetically hypertensive rats

Estimating the impact of drug addiction causes heart damage

To date, few studies have investigated the toxicological effects of the combined use of amphetamine and heroin in the heart. Hence, the aim of this study was to identify indicators for clinical evaluation and prevention of cardiac injury induced by the combined use of amphetamine and heroin. Four different groups were analyzed: (1) normal group (n＝25；average age＝35 ± 6.8); (2) heart disease group (n＝25；average age＝58 ± 17.2); (3) drug abusers (n = 27; average age = 37 ± 7.7); (4) drug abstainers (previous amphetamine-heroin users who had been drug-free for more than two weeks; n = 22; average age = 35 ± 5.6). The activity of MMPs, and levels of TNF-α, IL-6, GH, IGF-I, and several serum biomarkers were examined to evaluate the impact of drug abuse on the heart. The selected plasma biomarkers and classic cardiac biomarkers were significantly increased compared to the normal group. The zymography data showed the changes in cardiac-remodeling enzymes MMP-9 and MMP-2 among combined users of amphetamine and heroin. The levels of TNF-α and IL-6 only increased in the heart disease group. Growth hormone was increased; however, IGF-I level decreased with drug abuse and the level was not restored by abstinence. We speculated that the amphetamine-heroin users might pose risk to initiate heart disease even though the users abstained for more than two weeks. The activity change of MMP-9 and MMP-2 can be a direct reason affecting heart function. The indirect reason may be related to liver damage by drug abuse reduce IGF-1 production to protect heart function.

Integrated human organ-on-a-chip model for predictive studies of anti-tumor drug efficacy and cardiac safety

Traditional drug screening models are often unable to faithfully recapitulate human physiology in health and disease, motivating the development of microfluidic organs-on-a-chip (OOC) platforms that can mimic many aspects of human physiology and in the process alleviate many of the discrepancies between preclinical studies and clinical trials outcomes. Linsitinib, a novel anti-cancer drug, showed promising results in pre-clinical models of Ewing Sarcoma (ES), where it suppressed tumor growth. However, a Phase II clinical trial in several European centers with patients showed relapsed and/or refractory ES. We report an integrated, open setting, imaging and sampling accessible, polysulfone-based platform, featuring minimal hydrophobic compound binding. Two bioengineered human tissues - bone ES tumor and heart muscle - were cultured either in isolation or in the integrated platform and subjected to a clinically used linsitinib dosage. The measured anti-tumor efficacy and cardiotoxicity were compared with the results observed in the clinical trial. Only the engineered tumor tissues, and not monolayers, recapitulated the bone microenvironment pathways targeted by linsitinib, and the clinically-relevant differences in drug responses between non-metastatic and metastatic ES tumors. The responses of non-metastatic ES tumor tissues and heart muscle to linsitinib were much closer to those observed in the clinical trial for tissues cultured in an integrated setting than for tissues cultured in isolation. Drug treatment of isolated tissues resulted in significant decreases in tumor viability and cardiac function. Meanwhile, drug treatment in an integrated setting showed poor tumor response and less cardiotoxicity, which matched the results of the clinical trial. Overall, the integration of engineered human tumor and cardiac tissues in the integrated platform improved the predictive accuracy for both the direct and off-target effects of linsitinib. The proposed approach could be readily extended to other drugs and tissue systems.

Short-Term Treatment with Esmolol Reverses Left Ventricular Hypertrophy in Adult Spontaneously Hypertensive Rats via Inhibition of Akt/NF-κB and NFATc4

Our group has previously demonstrated that short-term treatment with esmolol reduces left ventricular hypertrophy (LVH) in spontaneously hypertensive rats (SHRs). The present study aimed to assess the molecular mechanisms related to this effect. Fourteen-month-old male SHR_s were treated intravenously with saline as vehicle (SHR) or esmolol (SHR-E) (300 μg/kg/min). Age-matched vehicle-treated male Wistar-Kyoto (WKY) rats served as controls. After 48 hours of treatment, the hearts were harvested and left ventricular tissue was separated and processed for Western blot analysis to determine the levels of Akt, NF-κB, NFATc4, Creb1, Serca2a, Erk1/2, and Sapk/Jnk. Biomarkers of oxidative stress, such as catalase, protein carbonyls, total thiols, and total antioxidant capacity were evaluated. Esmolol reversed the levels of p-NFATc4, p-Akt, and p-NF-κB in SHRs to the phospholevels of these proteins in WKY rats without modifying p-Erk1/2, p-Sapk/Jnk, p-Creb1, or Serca2a in SHR. Compared with SHR, esmolol increased catalase activity and reduced protein carbonyls without modifying total thiols or total antioxidant capacity. Short-term treatment with esmolol reverses LVH in aged SHRs by downregulation of Akt/NF-κB and NFATc4 activity. Esmolol treatment also increases catalase activity and reduces oxidative stress in SHRs with LVH.

Anti-Apoptotic and Pro-Survival Effect of Alpinate Oxyphyllae Fructus (AOF) in a d-Galactose-Induced Aging Heart

Aging, a natural biological/physiological phenomenon, is accelerated by reactive oxygen species (ROS) accumulation and identified by a progressive decrease in physiological function. Several studies have shown a positive relationship between aging and chronic heart failure (HF). Cardiac apoptosis was found in age-related diseases. We used a traditional Chinese medicine, Alpinate Oxyphyllae Fructus (AOF), to evaluate its effect on cardiac anti-apoptosis and pro-survival. Male eight-week-old Sprague–Dawley (SD) rats were segregated into five groups: normal control group (NC), d-Galactose-Induced aging group (Aging), and AOF of 50 (AL (AOF low)), 100 (AM (AOF medium)), 150 (AH (AOF high)) mg/kg/day. After eight weeks, hearts were measured by an Hematoxylin–Eosin (H&E) stain, Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-assays and Western blotting. The experimental results show that the cardiomyocyte apoptotic pathway protein expression increased in the d-Galactose-Induced aging groups, with dose-dependent inhibition in the AOF treatment group (AL, AM, and AH). Moreover, the expression of the pro-survival p-Akt (protein kinase B (Akt)), Bcl-2 (B-cell lymphoma 2), anti-apoptotic protein (Bcl-xL) protein decreased significantly in the d-Galactose-induced aging group, with increased performance in the AOF treatment group with levels of p-IGFIR and p-PI3K (Phosphatidylinositol-3′ kinase (PI3K)) to increase by dosage and compensatory performance. On the other hand, the protein of the Sirtuin 1 (SIRT1) pathway expression decreased in the aging groups and showed improvement in the AOF treatment group. Our results suggest that AOF strongly works against ROS-induced aging heart problems.

Mitochondrial dysfunction in cardiac aging

Cardiovascular diseases are the leading cause of death in most developed nations. While it has received the least public attention, aging is the dominant risk factor for developing cardiovascular diseases, as the prevalence of cardiovascular diseases increases dramatically with increasing age. Cardiac aging is an intrinsic process that results in impaired cardiac function, along with cellular and molecular changes. Mitochondria play a great role in these processes, as cardiac function is an energetically demanding process. In this review, we examine mitochondrial dysfunction in cardiac aging. Recent research has demonstrated that mitochondrial dysfunction can disrupt morphology, signaling pathways, and protein interactions; conversely, mitochondrial homeostasis is maintained by mechanisms that include fission/fusion, autophagy, and unfolded protein responses. Finally, we describe some of the recent findings in mitochondrial targeted treatments to help meet the challenges of mitochondrial dysfunction in aging.

The Heart Protection Effect of Alcalase Potato Protein Hydrolysate Is through IGF1R-PI3K-Akt Compensatory Reactivation in Aging Rats on High Fat Diets

The prevalence of obesity is high in older adults. Alcalase potato protein hydrolysate (APPH), a nutraceutical food, might have greater benefits and be more economical than hypolipidemic drugs. In this study, serum lipid profiles and heart protective effects were evaluated in high fat diet (HFD) induced hyperlipidemia in aging rats treated with APPH (15, 45 and 75 mg/kg/day) and probucol (500 mg/kg/day). APPH treatments reduced serum triacylglycerol (TG), total cholesterol (TC), and low density lipoprotein (LDL) levels to the normal levels expressed in the control group. Additionally, the IGF1R-PI3K-Akt survival pathway was reactivated, and Fas-FADD (Fas-associated death domain) induced apoptosis was inhibited by APPH treatments (15 and 45 mg/kg/day) in HFD aging rat hearts. APPH (75 mg/kg/day) rather than probucol (500 mg/kg/day) treatment could reduce serum lipids without affecting HDL expression. The heart protective effect of APPH in aging rats with hyperlipidemia was through lowering serum lipids and enhancing the activation of the compensatory IGF1R-PI3K-Akt survival pathway.

Magnolol administration in normotensive young spontaneously hypertensive rats postpones the development of hypertension: role of increased PPAR gamma, reduced TRB3 and resultant alleviative vascular insulin resistance

Patients with prehypertension are more likely to progress to manifest hypertension than those with optimal or normal blood pressure. However, the mechanisms underlying the development from prehypertension to hypertension still remain largely elusive and the drugs for antihypertensive treatment in prehypertension are absent. Here we determined the effects of magnolol (MAG) on blood pressure and aortic vasodilatation to insulin, and investigated the underlying mechanisms. Four-week-old male spontaneous hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto (WKY) control rats were used. Our results shown that treatment of young SHRs with MAG (100 mg/kg/day, o.g.) for 3 weeks decreased blood pressure, improved insulin-induced aorta vasodilation, restored Akt and eNOS activation stimulated by insulin, and increased PPARγ and decreased TRB3 expressions. In cultured human umbilical vein endothelial cells (HUVECs), MAG incubation increased PPARγ, decreased TRB3 expressions, and restored insulin-induced phosphorylated Akt and eNOS levels and NO production, which was blocked by both PPARγ antagonist and siRNA targeting PPARγ. Improved insulin signaling in HUVECs by MAG was abolished by upregulating TRB3 expression. In conclusion, treatment of young SHRs with MAG beginning at the prehypertensive stage decreases blood pressure via improving vascular insulin resistance that is at least partly attributable to upregulated PPARγ, downregulated TRB3 and consequently increased Akt and eNOS activations in blood vessels in SHRs.

Involvement of two distinct signalling pathways in IGF-1-mediated central control of hypotensive effects in normotensive and hypertensive rats

AIMS

Insulin-like growth factor-1 (IGF-1) is abundantly expressed in the nucleus tractus solitarii (NTS). In a previous study, we revealed that the induction of nitric oxide (NO) production in the NTS reduces blood pressure (BP). It is well known that both acute administration and chronic administration of IGF-I reduce BP. The aim of this study was to evaluate the short-term hypotensive effect of IGF-1 in the NTS and to delineate the underlying molecular mechanisms of IGF-1 in the NTS of normotensive WKY rats and spontaneously hypertensive rats (SHRs).

METHOD

Microinjections of the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and the MAP kinase-ERK kinase (MEK) inhibitor PD98059 into the NTS in WKY rats and SHRs were used to study the involvement of IGF-1-induced depressor effects.

RESULT

An IGF-1 (7.7 pmol) injection into the NTS resulted in a significant decrease in BP and HR in WKY rats and SHRs. Immunoblotting and immunohistochemical analysis showed that the microinjection of LY294002 (0.6 pmol) or PD98059 (3.0 pmol) into the NTS attenuated the IGF-1-induced depressor effects and Akt or ERK phosphorylation in WKY rats. An attenuation effect of LY294002, but not PD98059, was found in the SHRs. However, the mRNA and protein expression levels of the IGF-1R showed no significant differences in the NTS of the WKY rats and the SHRs.

CONCLUSION

These results suggest that distinct Akt and ERK signalling pathways mediated the IGF-1 control of the central depressor effects in WKY rats and SHRs. ERK signalling defects may be associated with the development of hypertension.

Myocardial AKT: the omnipresent nexus

One of the greatest examples of integrated signal transduction is revealed by examination of effects mediated by AKT kinase in myocardial biology. Positioned at the intersection of multiple afferent and efferent signals, AKT exemplifies a molecular sensing node that coordinates dynamic responses of the cell in literally every aspect of biological responses. The balanced and nuanced nature of homeostatic signaling is particularly essential within the myocardial context, where regulation of survival, energy production, contractility, and response to pathological stress all flow through the nexus of AKT activation or repression. Equally important, the loss of regulated AKT activity is primarily the cause or consequence of pathological conditions leading to remodeling of the heart and eventual decompensation. This review presents an overview compendium of the complex world of myocardial AKT biology gleaned from more than a decade of research. Summarization of the widespread influence that AKT exerts upon myocardial responses leaves no doubt that the participation of AKT in molecular signaling will need to be reckoned with as a seemingly omnipresent regulator of myocardial molecular biological responses.

Phosphorylated endothelial NOS Ser1177 via the PI3K/Akt pathway is depressed in the brain of stroke-prone spontaneously hypertensive rat

Stroke-prone spontaneously hypertensive rats (SHRSP) demonstrate impaired endothelium-dependent relaxation and often develop brain injuries. We investigated whether the regulatory mechanism for endothelial NOS (eNOS) phosphorylation and activation is altered in the cerebral cortex of SHRSP at a younger age. Western blot analysis revealed a low ratio of phosphor-eNOS (Ser1177) to total eNOS in SHRSP at 10 weeks of age. In addition, urinary nitric oxide metabolites (ie, nitrate and nitrite) were decreased compared with normal control WKY rats. Likewise, Akt phosphorylation (especially Ser473) was significantly reduced, with no changes in total Akt. Furthermore, the amount of the phosphatidylinositol 3-kinase (PI3K) was upstream of Akt was diminished, although attenuation of the PI3K/Akt pathway was not an effect of mTOR, another downstream target of Akt. Our findings indicate that abnormalities of the PI3K/Akt pathway in the cerebral cortex are involved in the impaired eNOS phosphorylation and activation in SHRSP.

Vascular insulin resistance in prehypertensive rats: role of PI3-kinase/Akt/eNOS signaling

It is well known that systemic insulin resistance is closely associated with the metabolic syndrome including type 2 diabetes and hypertension. However, it remains unclear whether vascular insulin resistance acts as an early etiologic factor for the development of hypertension. Male spontaneously hypertensive rats (SHRs) aged 5 weeks (young) and 15 weeks (adult) were studied and vascular insulin resistance was assessed as the function of isolated aortic vasodilatory response to insulin in vitro. Compared with Wistar-Kyoto (WKY) rats, adult SHRs exhibited significant hypertension with significantly decreased aortic vasodilatation to insulin, whereas young SHRs had normal blood pressure but exhibited similar vascular insulin resistance. Both young and adult SHRs showed significant downregulated expression of PI3-kinase and decreased insulin-stimulated phosphorylations of Akt and eNOS in vascular tissues. Treatment with rosiglitazone (RSG), an insulin sensitizer, for 2 weeks increased vascular PPARgamma expression and restored PI3-kinase/Akt/eNOS-mediated signaling pathway only in young SHRs. More importantly, this treatment improved aortic vasodilatory response to insulin in young but not in adult SHRs. In summary, vascular insulin resistance, characterized by the impairment of PI3-kinase/Akt/eNOS-mediated signaling in vascular endothelium, may play important roles in endothelial dysfunction and subsequent development of hypertension in normotensive young SHRs.

Cardiac function in young and old Little mice

We studied cardiac function in young and old, wild-type (WT), and longer-living Little mice using cardiac flow velocities, echocardiographic measurements, and left ventricular (LV) pressure (P) to determine if enhanced reserves were in part responsible for longevity in these mice. Resting/baseline cardiac function, as measured by velocities, LV dimensions, +dP/dt(max), and -dP/dt(max), was significantly lower in young Little mice versus young WT mice. Fractional shortening (FS) increased significantly, and neither +dP/dt(max) nor -dP/dt(max) declined with age in Little mice. In contrast, old WT mice had no change in FS but had significantly lower +dP/dt(max) and -dP/dt(max) versus young WT mice. Significant decreases were observed in the velocity indices of old Little mice versus old WT mice, but other parameters were unchanged. The magnitude of dobutamine stress response remained unchanged with age in Little mice, while that in WT mice decreased. These data suggest that while resting cardiac function in Little mice versus WT mice is lower at young age, it is relatively unaltered with aging. Additionally, cardiac function in response to stress was maintained with age in Little mice but not in their WT counterparts. Thus, some mouse models of increased longevity may not be associated with enhanced reserves.

Oxidative stress activates insulin-like growth factor I receptor protein expression, mediating cardiac hypertrophy induced by thyroxine

Thyroxine can cause cardiac hypertrophy by activating growth factors, such as IGF-I (insulin-like growth factor-I). Since oxidative stress is enhanced in the hyperthyroidism, it would control protein expression involved in this hypertrophy. Male Wistar rats were divided into four groups: (I) control, (II) vitamin E-supplemented (20 mg/kg/day subcutaneous), (III) hyperthyroid (thyroxine 12 mg/l, in drinking water), and (IV) hyperthyroid + vitamin E. After 4 weeks, the contractility and relaxation indexes of left ventricle (LV), and cardiac mass were increased by 54%, 60%, and 60%, respectively, in hyperthyroid group. An increase in lipid peroxidation (around 40%), and a decrease in total glutathione (by 20%) was induced by thyroxine and avoided by vitamin E administration. Superoxide dismutase (SOD) and glutathione-S-transferase (GST) activities were increased (by 83% and 54%, respectively) in hyperthyroid, and vitamin E avoided changes in SOD. Protein expression of SOD, GST, and IGF-I receptor (IGF-IR) were increased (by 87%, 84%, and 60%, respectively) by thyroxine, and vitamin E promoted a significant reduction in SOD and IGF-IR expression (by 36% and 17%, respectively). These results indicate that oxidative stress is involved in cardiac hypertrophy, and suggest a role for IGF-IR as a mediator of this adaptive response in experimental hyperthyroidism.

Down regulation of IGF-I and IGF-IR gene expression in right atria tissue of ventricular septal defect infants with right atria hypoxemia

BACKGROUND

Our previous studies showed serum insulin-like growth factor-I (IGF-I) concentrations significantly decreased in infants with congenital ventricular septal defect (VSD) and that they were associated with increased concentrations of growth hormone. In order to confirm the relationship between IGF-I axis and VSD, we further compared the IGF-I and insulin-like growth factor-I receptor(IGF-IR) gene expressions in the cardiac tissue of VSD infants.

METHODS

Right atrium biopsies of 27 infants were studied. Five infants not having VSD were classified as controls (Group I). Twenty VSD patients were then divided into 2 groups according to their shunting magnitude index (level of pulmonary vascular resistance compared with systemic vascular resistance, Qp/Qs). VSD patients with minor shunts (Qp/Qs<1.7) were classified as Group II; VSD patients with larger shunts (Qp/Qs> or =2) as Group III. Besides, seven tetralogy of fallot (TOF) with shunt (Qp/Qs>4) infants were classified as the Group IV. A non-radioactive DIG-RNA probe detection system, western blotting and immunohistochemistry were used to detect the gene expression levels and protein products of IGF-I and IGF-IR in the right atrium samples of VSD infants.

RESULTS

The relative protein levels of IGF-I were 0.96+/-0.05, 0.43+/-0.03, 0.15+/-0.04, 0.12+/-0.03 and IGF-IR were 0.80+/-0.08, 0.57+/-0.03, 0.38+/-0.02, 0.24+/-0.04 in the right atrium of 4 group patients. The relative mRNA levels of IGF-I were 0.95+/-0.01, 0.41+/-0.03, 0.29+/-0.05, 0.15+/-0.01 and IGF-IR were 0.85+/-0.05, 0.56+/-0.03, 0.17+/-0.01, 0.18+/-0.01, respectively. There was a significantly greater but more gradual decrease in protein levels and in mRNA levels of IGF-I and IGF-IR in Group II (p<0.05), Group III and IV (p<0.01) than in Group I. The results of immunohistochemistry also demonstrated a similar decrease in VSD patients. In addition, the decrease of mRNA and protein levels in IGF-I/IGF-IR of VSD patients show related to the saturation of oxygen in the right atrium and the ratio of systolic right ventricular pressure to left ventricular pressure.

CONCLUSION

We further confirmed the down regulation of IGF-I/IGF-IR in cardiac tissue of VSD infants and the decrease to be associated with shunt magnitude and the severity of hypoxemia in the cardiac chamber of VSD.

Interaction between CYP1A1 T3801C and AHR G1661A polymorphisms according to smoking status on blood pressure in the Stanislas cohort

BACKGROUND

CYP1A1, one of the key enzymes in detoxifying toxic components produced during cigarette smoking, is regulated by aromatic hydrocarbon receptor (AHR). A CYP1A1 T3801C polymorphism, associated with a higher CYP1A1 inducibility and enhanced catalytic activity, has been linked to stroke, triple vessel disease and may, therefore, be associated with blood pressure (BP). The relation of the widely studied G1661A polymorphism of the human AHR gene with BP is unknown.

OBJECTIVES

To investigate the genetic influence of CYP1A1 T3801C and AHR G1661A polymorphisms on BP in relation to tobacco consumption.

DESIGN AND PARTICIPANTS

Study participants were selected from a French longitudinal cohort of volunteers for a free health check-up. These individuals (302 men and 311 women) were not taking medication that can affect blood pressure. Information about active smoking status was obtained by a self-administered questionnaire.

RESULTS

After multiple regression analysis, systolic blood pressure (SBP) and diastolic blood pressure (DBP) did not differ significantly according to their tobacco status excepted for DBP in men. In addition, neither CYP1A1 T3801C nor AHR G1661A polymorphism was linked to blood pressure. However, systolic and diastolic blood pressures differed significantly according to CYP1A1 T3801C genotype between ex-smokers and smokers. Finally, the interaction between CYP1A1 T3801C and AHR G1661A polymorphisms explained a significant difference of SBP and DBP between carriers of both CYP1A1-C3801 and AHR-A1661 alleles.

CONCLUSION

This study is the first to show an interaction between the CYP1A1 T3801C and AHR G1661A polymorphisms. This interaction could explain the difference in blood pressure level between smokers and non-smokers/ex-smokers but needs to be confirmed in a large sample.

Alteration of Insulin-like Growth Factor-1 Expression After Middle Cerebral Artery Occlusion in Monkeys and Rats: Complementary DNA Microarray, Immunohistochemistry, and In Situ Hybridization Studies

It is well established that insulin-like growth factor (IGF)-1 has potent neuroprotective effects on cerebral ischemia in the rat and sheep model. In order to investigate whether it has neuroprotective effects on brain insult in human stroke, as one part of serial subhuman primate stroke research, the present study was designed to observe whether IGF-1 messenger RNA (mRNA) and protein is expressed in middle cerebral artery occlusion in monkeys and rats. A total of 12,800 dots complementary DNA microarray, in situ hybridization, and immunohistochemistry were used. Complementary DNA microarray showed that among the nearly 8000 genes, approximately 8% of the total number of genes examined was affected after ischemia/reperfusion injury especially in the growth factor family including IGF-1 in the ischemic region. The decreased IGF-1 mRNA and protein expression was found in the insular striatum, but there was an increased mRNA expression and unchanged protein expression in the hippocampus 24 hours after ischemia. The results suggested that IGF-1 might contribute to the neuroprotective pathway in a pattern different from that of rats, and it might play a role in protection of ischemic injured neuronal cells after monkey focal cerebral ischemia.