Central cardiovascular effects of baclofen in spontaneously hypertensive rats

This study was conducted to investigate the effects of centrally administered baclofen on blood pressure and heart rate in conscious spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Administration of baclofen (1.0 microgram/kg) into the lateral cerebral ventricle (icv) produced an increase in mean arterial pressure (MAP) in both SHR and WKY rats. The increase in MAP was significantly lower in SHR (13 +/- 3 mmHg) when compared with WKY (27 +/- 5 mmHg). The changes in heart rate (HR) were variable, from no change to a very small increase and did not differ significantly between SHR and WKY rats. The ability of baclofen to interfere with baroreceptor reflexes was also tested in separate experiments. In SHR, icv injection of baclofen (1.0 microgram/kg) significantly suppressed the pressor response and bradycardia evoked by phenylephrine 3.0 micrograms/kg iv, whereas in WKY, the pressor and HR responses to similar injections of phenylephrine were not affected by icv baclofen. Similarly, baclofen treatment modified hypotensive response and reflex tachycardia induced by nitroprusside (10.0 micrograms/kg) iv in SHR but not in WKY rats. Administration of sympathetic ganglionic blocker hexamethonium (HEX; 25 mg/kg) iv produced an equivalent decrease in MAP between SHR and WKY following icv injection of baclofen (1.0 microgram/kg). These results suggest that the effects of baclofen on the baroreceptor reflexes in SHR may not be mediated by a change in peripheral sympathetic tone.     

Anti‐inflammaging effects of human alpha‐1 antitrypsin

Inflammaging plays an important role in most age‐related diseases. However, the mechanism of inflammaging is largely unknown, and therapeutic control of inflammaging is challenging. Human alpha‐1 antitrypsin (hAAT) has immune‐regulatory, anti‐inflammatory, and cytoprotective properties as demonstrated in several disease models including type 1 diabetes, arthritis, lupus, osteoporosis, and stroke. To test the potential anti‐inflammaging effect of hAAT, we generated transgenic Drosophila lines expressing hAAT. Surprisingly, the lifespan of hAAT‐expressing lines was significantly longer than that of genetically matched controls. To understand the mechanism underlying the anti‐aging effect of hAAT, we monitored the expression of aging‐associated genes and found that aging‐induced expressions of Relish (NF‐?B orthologue) and Diptericin were significantly lower in hAAT lines than in control lines. RNA‐seq analysis revealed that innate immunity genes regulated by NF‐kB were significantly and specifically inhibited in hAAT transgenic Drosophila lines. To confirm this anti‐inflammaging effect in human cells, we treated X‐ray‐induced senescence cells with hAAT and showed that hAAT treatment significantly decreased the expression and maturation of IL‐6 and IL‐8, two major factors of senescence‐associated secretory phenotype. Consistent with results from Drosophila,RNA‐seq analysis also showed that hAAT treatment significantly inhibited inflammation related genes and pathways. Together, our results demonstrated that hAAT significantly inhibited inflammaging in both Drosophila and human cell models. As hAAT is a FDA‐approved drug with a confirmed safety profile, this novel therapeutic potential may make hAAT a promising candidate to combat aging and aging‐related diseases.     

Hypothalamic cardiovascular effects of angiotensin-(1-7) in spontaneously hypertensive rats

The objective of the present work was to study the cardiovascular actions of the intrahypothalamic injection of Ang-(1-7) and its effects on the pressor response to Ang II in spontaneously hypertensive (SH) rats and Wistar Kyoto (WKY) animals. In anaesthetized SH and WKY rats, a carotid artery was cannulated for mean arterial pressure (MAP) measurement and a stainless-steel needle was inserted into the anterior hypothalamus for drug administration. The cardiovascular effects of the intrahypothalamic administration of Ang-(1-7) were determined in SH and WKY rats. In SH rats, the effect of irbesartan and D-Ala-Ang-(1-7) on Ang-(1-7) cardiovascular effect was also evaluated. Ang II was administered in the hypothalamus of SH and WKY rats and changes in blood pressure and heart rate were measured followed by the administration of Ang II, Ang II+Ang-(1-7) or Ang II+D-Ala-Ang-(1-7). Ang-(1-7) did not the change basal MAP in WKY rats, but induced a pressor response in SH animals. Whilst the co-administration of D-Ala-Ang-(1-7) did not affect the response to Ang-(1-7), the previous administration of irbesartan prevented the effect of the peptide. The intrahypothalamic injection of Ang II induced a significantly greater pressor response in SH animals compared to normotensive rats. The co-administration of Ang-(1-7) with Ang II did not affect the pressor response to Ang II in the WKY group. In SH rats, whilst the co-administration of Ang-(1-7) with Ang II reduced the pressor response to Ang II, the concomitant application of D-Ala-Ang-(1-7) with Ang II increased the pressor response to the octapeptide after 5 and 10 min of intrahypothalamic administration. In conclusion, our result demonstrated that the biologically active peptide Ang-(1-7) did not participate in the hypothalamic blood pressure regulation of WKY animals. In SH rats, Ang-(1-7) exerted pleiotropic effects on blood pressure regulation. High dose of the heptapeptide produced a pressor response because of an unspecific action by activation of AT1 receptors. The concomitant administration of lower doses of Ang-(1-7) with Ang II reduced the pressor response to the octapeptide. Finally, the effect of AT(1-7) antagonist on Ang II pressor response suggested that hypothalamic formed Ang-(1-7) are implicated in the regulation of the cardiovascular effects of Ang II.     

Central reactive oxygen species mediate cardiovascular effects of urotensin II in spontaneously hypertensive rats

Central urotensin II (UII) may participate in the regulation of cardiovascular functions by stimulating sympathy pathway. However, the central mechanism remained unknown. Recent studies have shown that brain reactive oxygen species (ROS) mediate the sympatho-excitatory effects. In the present study, we tested the hypothesis that ROS mediate central cardiovascular effects of UII. Experiments were conducted in Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). Immunocytochemistry, intracerebroventricular (icv) infusion and lucigenin-enhanced chemiluminescence assay were employed to detect UII receptor expression and ROS level, respectively. The following results were obtained: (1) Expressions of UII receptors of rostral ventrolateral medulla (RVLM) and nucleus tractus solitarii (NTS) were increased in SHR rats compared with WKY rats (P < 0.05). (2) UII (icv) significantly increased mean arterial pressure (MAP) (P < 0.05), and the effect of UII was significantly more pronounced in SHR rats than that in WKY rats (P < 0.05); (3) Tempol (a superoxide dismutase mimic) or Urantide (an antagonist of UII receptor) pretreatments eliminated the pressor effect of UII (P < 0.05) in SHR rats; (4) Brain superoxide level was increased in UII-treated SHR rats compared with that in cerebrospinal fluid (CSF)-treated SHR rats (P < 0.05). These results indicate that ROS mediate central cardiovascular effects of UII in SHR rats and provide evidence for a novel relationship between UII and ROS.     

Hyperhomocysteinemia leads to adverse cardiac remodeling in hypertensive rats

Hyperhomocysteinemia (Hhe), linked to cardiovascular disease by epidemiological studies, may be an important factor in adverse cardiac remodeling in hypertension. Specifically, convergence of myocardial and vascular alterations promoted by Hhe and hypertension may exacerbate cardiac remodeling and myocardial dysfunction. We studied male spontaneously hypertensive rats fed one of three diets: control, intermediate Hhe inducing, or severe Hhe inducing. After 10 wk of dietary intervention, cardiac function was assessed in vitro, and cardiac and coronary arteriolar remodeling were monitored by histomorphometric, immunohistochemical, and biochemical techniques. Results showed that Hhe induced diastolic dysfunction, as characterized by the diastolic pressure-volume curve, without significant changes in baseline systolic function. Perivascular collagen levels were increased by Hhe, and there was an increase in left ventricular hydroxyproline levels. Myocyte size was not affected. Coronary arteriolar wall thickness increased with Hhe due to smooth muscle hyperplasia. Mast cells increased in parallel with Hhe and collagen accumulation. In summary, 10 wk of Hhe caused coronary arteriolar remodeling, myocardial collagen deposition, and diastolic dysfunction in hypertensive rats.     

Chronic effects of centrally administered adiponectin on appetite, metabolism and blood pressure regulation in normotensive and hypertensive rats

Acute studies suggest that adiponectin may reduce sympathetic activity and blood pressure (BP) via actions on the central nervous system (CNS). However, the chronic effects of adiponectin on energy expenditure and cardiovascular function are still poorly understood. We tested if chronic intracerebroventricular (ICV) infusion of adiponectin (1 or 7μg/day) in Sprague-Dawley rats fed a high fat diet (HFD) for 8 weeks and at the high dose (7μg/day) in spontaneously hypertensive rats (SHRs), a hypertensive model associated with sympathetic overactivity, evoked chronic reductions in BP and heart rate (HR). We also determined if chronic ICV adiponectin infusion alters appetite, whole body oxygen consumption (VO(2)), and insulin and leptin levels. Neither dose of adiponectin infused for 7 days significantly altered BP or HR in the HFD group (115±2 to 112±2mmHg and 384±6 to 379±6bpm at 1μg/day; 109±3 to 111±3mmHg and 366±5 and 367±5bpm at 7μg/day). The higher dose slightly reduced food intake (14±1 to 11±1g/day), whereas VO(2), insulin and leptin levels were not affected by the treatment. In SHRs, ICV adiponectin infusion reduced appetite (22±2 to 12±2g/day) and insulin levels (～55%), but did not alter BP (162±4 to 164±3mmHg) or HR (312±5 to 322±8bpm). These results suggest that adiponectin, acting via its direct actions on the CNS, has a small effect to reduce appetite and insulin levels, but it has no long-term action to reduce BP or HR, or to alter whole body metabolic rate.     

Anti‐inflammatory effects of melatonin in a rat model of caerulein‐induced acute pancreatitis

The purpose of our study was to evaluate the protective effect of melatonin in a rat model of caerulein‐induced acute pancreatitis. For the induction of experimental acute pancreatitis, four subcutaneous injections of caerulein (20 µg kg^–1 body weight) were given to Wistar rats at 2‐h intervals. Melatonin was injected intraperitoneally (25 mg kg^–1 body weight) 30 min before each caerulein injection. After 12 h, rats were sacrificed by decapitation. Blood and pancreas samples were collected and processed for serological and histopathological studies, respectively. Lipase, α‐amylase, corticosterone, total antioxidant power and cytokines interleukin (IL)‐1β, IL‐4 and tumour necrosis factor (TNF)‐α were determined using commercial kits. ANOVA and Tukey tests (P < 0.05) were performed for the statistical analysis of the results. Results showed that the administration of melatonin reduced histological damage induced by caerulein treatment as well as the hyperamylasemia and hyperlipidemia. Corticosterone and antioxidant total power were also reverted to basal activities. Furthermore, melatonin pre‐treatment reduced pro‐inflammatory cytokines IL‐1β and TNF‐α and increased the serum levels of anti‐inflammatory cytokine IL‐4. In conclusion, the findings suggest that the protective effect of melatonin in caerulein‐induced acute pancreatitis is mediated by the anti‐inflammatory ability of this indolamine. Thus, melatonin may have a protective effect against acute pancreatitis. Copyright © 2013 John Wiley & Sons, Ltd.     

Akt‐mediated anti‐apoptotic effects of substance P in Anti‐Fas‐induced apoptosis of human tenocytes

Substance P (SP) and its receptor, the neurokinin‐1 receptor (NK‐1 R), are expressed by human tenocytes, and they are both up‐regulated in cases of tendinosis, a condition associated with excessive apoptosis. It is known that SP can phosphorylate/activate the protein kinase Akt, which has anti‐apoptotic effects. This mechanism has not been studied for tenocytes. The aims of this study were to investigate if Anti‐Fas treatment is a good apoptosis model for human tenocytes in vitro, if SP protects from Anti‐Fas‐induced apoptosis, and by which mechanisms SP mediates an anti‐apoptotic response. Anti‐Fas treatment resulted in a time‐ and dose‐dependent release of lactate dehydrogenase (LDH), i.e. induction of cell death, and SP dose‐dependently reduced the Anti‐Fas‐induced cell death through a NK‐1 R specific pathway. The same trend was seen for the TUNEL assay, i.e. SP reduced Anti‐Fas‐induced apoptosis via NK‐1 R. In addition, it was shown that SP reduces Anti‐Fas‐induced decrease in cell viability as shown with crystal violet assay. Protein analysis using Western blot confirmed that Anti‐Fas induces cleavage/activation of caspase‐3 and cleavage of PARP; both of which were inhibited by SP via NK‐1 R. Finally, SP treatment resulted in phosphorylation/activation of Akt as shown with Western blot, and it was confirmed that the anti‐apoptotic effect of SP was, at least partly, induced through the Akt‐dependent pathway. In conclusion, we show that SP reduces Anti‐Fas‐induced apoptosis in human tenocytes and that this anti‐apoptotic effect of SP is mediated through NK‐1 R and Akt‐specific pathways.     

Involvement of hypothalamic neuropeptide Y in regulating the amphetamine-induced appetite suppression in streptozotocin diabetic rats

BACKGROUND AND AIM: Amphetamine (AMPH) is a well-known anorectic agent. In normal rats, AMPH-induced anorexia has been attributed to its inhibitory action on hypothalamic neuropeptide Y (NPY), an appetite stimulant in the brain. In diabetic rats, however, if this anorectic response of AMPH might still be observed was uncertain. METHODS: Rats (including normal, diabetic and insulin-treated diabetic rats) were given daily with saline or AMPH for 6 days. Changes in food intake, plasma glucose level (PGL) and NPY content of these rats were measured and compared. RESULTS: The AMPH-induced anorectic response was altered in diabetic rats. Although the anorectic effects of AMPH on the first day of dosing were similar between diabetic and control rats, diabetic rats developed tolerance to this anorexia more rapidly than control rats. This alteration was independent of PGL since PGL levels were not changed following AMPH treatment and PGL normalization induced by phlorizin could not restore the level of AMPH anorexia. On the other hand, this alteration was dependent on the action of NPY because NPY contents were decreased following AMPH treatment and the replacement of insulin in diabetic rats could restore both NPY content and AMPH anorexia. CONCLUSION: These results suggested that the elevated hypothalamic NPY content in diabetic rats was involved in modifying the anorectic response of AMPH.     

Anti‐angiogenic effects of the blue‐green alga Arthrospira platensis on pancreatic cancer

Arthrospira platensis, a blue‐green alga, is a popular nutraceutical substance having potent antioxidant properties with potential anti‐carcinogenic activities. The aim of our study was to assess the possible anti‐angiogenic effects of A platensis in an experimental model of pancreatic cancer. The effects of an A platensis extract were investigated on human pancreatic cancer cells (PA‐TU‐8902) and immortalized endothelial‐like cells (Ea.hy926). PA‐TU‐8902 pancreatic tumours xenografted to athymic mice were also examined. In vitro migration and invasiveness assays were performed on the tested cells. Multiple angiogenic factors and signalling pathways were analysed in the epithelial, endothelial and cancer cells, and tumour tissue. The A platensis extract exerted inhibitory effects on both migration and invasion of pancreatic cancer as well as endothelial‐like cells. Tumours of mice treated with A platensis exhibited much lesser degrees of vascularization as measured by CD31 immunostaining (P = .004). Surprisingly, the VEGF‐A mRNA and protein expressions were up‐regulated in pancreatic cancer cells. A platensis inhibited ERK activation upstream of Raf and suppressed the expression of ERK‐regulated proteins. Treatment of pancreatic cancer with A platensis was associated with suppressive effects on migration and invasiveness with various anti‐angiogenic features, which might account for the anticancer effects of this blue‐green alga.     

Anti‐inflammatory effects of activated protein C on human dendritic cells

Activated protein C (APC) has an anticoagulant action and plays an important role in blood coagulation homeostasis. In addition to its anticoagulant action, APC is known to have cytoprotective effects, such as anti‐apoptotic action and endothelial barrier protection, on vascular endothelial cells and monocytes. However, the effects of APC on DCs have not been clarified. To investigate the effects of APC on human DCs, monocytes were isolated from peripheral blood and DC differentiation induced with LPS. APC significantly inhibited the production of inflammatory cytokines TNF‐α and IL‐6 during differentiation of immature DCs to mature DCs, but did not inhibit the production of IL‐12 and anti‐inflammatory cytokine IL‐10. Interestingly, treatment with 5 μg/mL, but not 25 μg/mL, of APC significantly enhanced production of IL‐10. In addition, protein C, which is the zymogen of APC, did not affect production of these cytokines. On the other hand, flow cytometric analysis of DC's surface molecules indicated that APC does not significantly affect expression of CD83, a marker of mDC differentiation, and the co‐stimulatory molecules CD40, CD80 and CD86. These results suggest that APC has anti‐inflammatory effects on human DCs and may be effective against some inflammatory diseases in which the pathogenesis involves TNF‐α and/or IL‐6 production.     

Disposition of catecholamines in cardiovascular tissues of aorta coarcted hypertensive rats

Aorta-coarcted hypertensive rats and sham-operated normotensive rats were compared in order to assess the contribution of sympathetic nervous system activity to the elevated blood pressure in these rats at an early (6 days) and chronic (42 days) stage of hypertension. Norepinephrine (NE), epinephrine (E) and dopamine (DA) levels were quantitated in plasma, heart and vascular tissues (aorta, inferior vena cava, mesenteric artery and vein) using a radioenzymatic procedure. Body weight was significantly reduced and mean arterial blood pressure (MABP) significantly increased in the coarcted rats at both stages of hypertension. Plasma catecholamines did not differ at either stage of hypertension. The NE content of the heart and mesenteric artery was significantly decreased in the coarcted rats at both stages of hypertension but unchanged in the other vessels studied. E and DA levels in the heart and all vasculature analyzed remained unaltered at both stages of hypertension. The present results suggest that neither E nor DA makes a major contribution to the development and maintenance of hypertension in the aorta-coarcted rat. The observation of the reduced cardiac NE concentration in the coarcted rats together with literature reports of similar observations in other animal models of hypertension suggests that myocardial NE depletion is a common feature of the hypertension and not dependent on the methodology used to produce that hypertension.