Impact of cold adaptation on cardiac tolerance to ischemia/reperfusion and glucocorticoid, thyroid hormone levels.

We have established that the continuous cold exposure (CCE, 4°C, 4 weeks) causes cold adaptation, increases systolic blood pressure, exerts infarct-limiting effect during coronary artery occlusion (45 min) and reperfusion (2 h). The CCE increases adrenal weight, heart weight and triiodothyronine (T3) level but does not change thymus, spleen weight, serum cortisol, corticosterone and thyroxin (T4) levels. The long-term (4°C, 8 h/day, 4 weeks) intermittent cold exposure (LICE) induces adaptation to the cold and increases T4 level. The brief (4°C, 1.5 h/day, 4 weeks) intermittent cold exposure (BICE) also evokes adaptation to the cold but had no effect on the blood pressure, the cardiac tolerance to ischemia/reperfusion, and does not change thymus, spleen weight, serum cortisol, corticosterone, T3 and T4 levels.

Design, synthesis, and biological evaluation of 2-substituted-2,3,4,9-tetrahydrospiro-ß-carboline-3-carboxylic acid derivatives as first-in-class mast cell stabilizers.

Mast cell degranulation plays a momentous role in myriad diseases like asthma, eczema, allergic rhinitis, and conjunctivitis as well as anaphylactic shock; hence, there is an unmet need for developing new mast cells stabilizers. The reported mast cell stabilizers have a heterocyclic moiety and an acidic group. Furthermore, the role of tryptophan in suppression of mast cell activation is established. Hence, we prepared constrained analogs of tryptophan, which are derivatives of 2,3,4,9-tetrahydrospiro-ß-carboline-3-carboxylic acid, and evaluated them for ex vivo inhibition of compound 48/80-induced mast degranulation activity. By comparing IC50 (µM) values with that of the standard drug sodium cromoglycate (IC50 = 0.489 ± 0.003 µM), compounds with bulky groups like heptyl (compound 9; IC50 = 0.389 ± 0.015 µM) and octyl (compound 10; IC50 = 0.354 ± 0.023 µM) were found to be of similar potency as sodium cromoglycate. Furthermore, the polar group-containing compounds like the chloropropyl (compound 16; IC50 = 0.382 ± 0.083 µM) and benzoyl derivative (compound 14; IC50 = 00.469 ± 0.032 µM) were also found to be of similar potency as sodium cromoglycate. This is a seminal study of spiro-ß-carboline mast cell stabilization having a wider scope in mast cell research; yet, the mechanism of action remains elusive.

Silymarin and Its Role in Chronic Diseases.

Silymarin is the active constituent of Silybum marianum (milk thistle) which is a C-25 containing flavonolignan. Milk thistle has a lot of traditional values, being used as a vegetable, as salad, as bitter tonic, and as galactogogue in nursing mothers and in various ailments such as liver complications, depression, dyspepsia, spleenic congestions, varicose veins, diabetes, amenorrhea, uterine hemorrhage, and menstrual problems. In this present chapter, a comprehensive attempt has been made to discuss the potential of silymarin in chronic disorders. An insight into modulation of cellular signaling by silymarin and its implication in various disorders such as liver disorders, inflammatory disorders, cancer, neurological disorders, skin diseases, and hypercholesterolemia is being provided.

Pharmacologic investigations on the role of Sirt-1 in neuroprotective mechanism of postconditioning in mice.

BACKGROUND: Cerebral ischemia-reperfusion (I-R) injury is one of the primary causes of ischemic stroke. Ischemic postconditioning (iPoCo) is evolving as an important adaptive technique to contain I-R injury. Some recent studies have shown neuroprotective effects of iPoCo. However, the neuroprotective mechanism of iPoCo is not clear. So, the present study has been undertaken to investigate the possible role of Sirtinol, a selective class III histone deacetylase (HDAC) inhibitor in the neuroprotective mechanism of iPoCo in mice. MATERIAL AND METHODS: Bilateral carotid artery occlusion (BCAO) for 12 min followed by reperfusion for 24 h was used to produce I-R-induced cerebral injury in Swiss albino mice. iPoCo involving three episodes of 10-s carotid artery occlusion and reperfusion instituted immediately after BCAO just before prolonged reperfusion of 24 h. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using a Morris water maze test. Rotarod test, inclined beam-walking test, and neurologic severity score (NSS) were used to assess motor incoordination. Acetylcholine esterase levels, brain thiobarbituric acid reactive species (TBARS), and glutathione level were also estimated. RESULTS: BCAO for 12 min followed by reperfusion for 24 h produced a significant rise in cerebral infarct size and NSS along with impairment of memory and motor coordination and biochemical alteration (↑acetylcholine esterase, ↓glutathione, and ↑TBARS). iPoCo, involving three episodes of 10-s carotid artery occlusion with intermittent reperfusion of 10 s applied just after ischemic insult of 12 min produced a significant decrease in cerebral infarct size and NSS along with the reversal of I-R-induced impairment of memory and motor coordination. iPoCo-induced neuroprotective effects were significantly abolished by pretreatment with selective SIRT 1 (class III HDAC) blocker Sirtinol (10 mg/kg intraperitoneal). CONCLUSIONS: It may be concluded that the neuroprotective effect of iPoCo probably involves activation of SIRT 1 (class III HDAC) enzyme.

Possible role of pannexin 1/P2x7 purinoceptor in neuroprotective mechanism of ischemic postconditioning in mice.

BACKGROUND: Previous studies have suggested a significant role of pannexin 1 (Panx1)/P2X7 receptor complex in cardioprotective mechanism of ischemic preconditioning and postconditioning (IPC). The present study has been undertaken to investigate whether Panx1/P2X7 purinoceptors are also involved in the neuroprotective mechanism of IPC in mice. MATERIALS AND METHODS: Bilateral carotid artery occlusion (BCAO) for 12 min followed by reperfusion for 24 h was used to produce ischemia-reperfusion-induced cerebral injury in Swiss albino mice. For IPC immediately after BCAO of 12 min, three cycles of 10-s ischemia and reperfusion each were given and then prolonged reperfusion of 24 h was used. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was evaluated using a Morris water maze test. Rotarod test, inclined beam walking test, and neurologic severity score (NSS) were used to assess motor dysfunction. Acetylcholine esterase levels, brain thiobarbituric acid reactive species, and glutathione level were also estimated. RESULTS: BCAO followed by reperfusion produced a significant increase in cerebral infarct size, NSS along with impairment of memory and motor dysfunction. It also increased brain acetylcholine esterase, thiobarbituric acid reactive species levels, and decreased the glutathione level. IPC produced a significant decrease in the cerebral infarct size and NSS along with reversal of ischemia-reperfusion-induced impairment of memory, motor dysfunction, and altered biochemical levels in the brain. IPC-induced neuroprotective effects were significantly abolished by pretreatment of mefloquine (15.0 mg/kg orally; 30.0 mg/kg orally), blocker of Panx1/P2X7 purinoceptor. CONCLUSIONS: Therefore, activation of Panx1/P2X7 purinoceptors appears to play a significant role in the neuroprotective mechanism of IPC.

Ameliorative potential of Ocimum sanctum in chronic constriction injury-induced neuropathic pain in rats.

The present study was designed to investigate the ameliorative potential of Ocimum sanctum and its saponin rich fraction in chronic constriction injury-induced neuropathic pain in rats. The chronic constriction injury was induced by placing four loose ligatures around the sciatic nerve, proximal to its trifurcation. The mechanical hyperalgesia, cold allodynia, paw heat hyperalgesia and cold tail hyperalgesia were assessed by performing the pinprick, acetone, hot plate and cold tail immersion tests, respectively. Biochemically, the tissue thio-barbituric acid reactive species, super-oxide anion content (markers of oxidative stress) and total calcium levels were measured. Chronic constriction injury was associated with the development of mechanical hyperalgesia, cold allodynia, heat and cold hyperalgesia along with an increase in oxidative stress and calcium levels. However, administration of Ocimum sanctum (100 and 200 mg/kg p.o.) and its saponin rich fraction (100 and 200 mg/kg p.o.) for 14 days significantly attenuated chronic constriction injury-induced neuropathic pain as well as decrease the oxidative stress and calcium levels. It may be concluded that saponin rich fraction of Ocimum sanctum has ameliorative potential in attenuating painful neuropathic state, which may be attributed to a decrease in oxidative stress and calcium levels.

Pharmacological investigations on possible role of Src kinases in neuroprotective mechanism of ischemic postconditioning in mice.

The present study has been undertaken to investigate the possible role of Src Kinases in a neuroprotective mechanism of ischemic postconditioning in mice. Bilateral carotid artery occlusion for 12 min followed by reperfusion for 24 h produced a significant increase in cerebral infarct size and neurological severity score along with impairment of memory and motor coordination. Ischemic postconditioning involving three episodes of 10 s carotid artery occlusion with intermittent reperfusion of 10 s proceeding ischemic insult of 12 min, produced a significant decrease in cerebral infarct size and neurological severity score along with reversal of ischemia-reperfusion induced impairment of memory and motor coordination. Ischemic postconditioning induced neuroprotective effects were significantly attenuated by pre-treatment of selective Src Kinase inhibitors SU-6656 (4 mg/kg i.p.) and PP1 (0.2 mg/kg i.p.). It may be concluded that the neuroprotective effect of ischemic postconditioning probably involves activation of Src Kinase pathway.

Ameliorative Effect of a Selective Endothelin ETA Receptor Antagonist in Rat Model of L-Methionine-induced Vascular Dementia.

The present study was designed to investigate the efficacy of selective ETA receptor antagonist, ambrisentan on hyperhomocysteinemia-induced experimental vascular dementia. L-methionine was administered for 8 weeks to induce hyperhomocysteinemia and associated vascular dementia in male rats. Ambrisentan was administered to L-methionine-treated effect rats for 4 weeks (starting from 5(th) to 8(th) week of L-methionine treatment). On 52(nd) day onward, the animals were exposed to the Morris water maze (MWM) for testing their learning and memory abilities. Vascular endothelial function, serum nitrite/nitrate levels, brain thiobarbituric acid reactive species (TBARS), brain reduced glutathione (GSH) levels, and brain acetylcholinesterase (AChE) activity were also measured. L-methionine-treated animals showed significant learning and memory impairment, endothelial dysfunction, decrease in/serum nitrite/nitrate and brain GSH levels along with an increase in brain TBARS levels and AChE activity. Ambrisentan significantly improved hyperhomocysteinemia-induced impairment of learning, memory, endothelial dysfunction, and changes in various biochemical parameters. These effects were comparable to that of donepezil serving as positive control. It is concluded that ambrisentan, a selective ETA receptor antagonist may be considered as a potential pharmacological agent for the management of hyperhomocysteinemia-induced vascular dementia.

Clinical Applicability of Conditioning Techniques in Ischemia-Reperfusion Injury: A Review of the Literature.

Ischemia refers to a reduced supply of oxygen and nutrient to the vital organ of the body. Reperfusion to the ischemic organ is the only way to salvage injury due to ischemia. Paradoxically, reperfusion itself induces the injury, which is more severe than the previous injury referred to as ischemia-reperfusion injury. Ischemia-reperfusion injury is the major cause of mortality in the case of ischemic diseases. The major hurdle for a clinician to treat ischemia is the reperfusion injury, which is encountered in different surgical as well as non-surgical situations. Several therapies, such as anti-platelets, anti-thrombolytic agents have been developed to contain ischemia-reperfusion injury, but with limited success. Over some time, some conditioning techniques such as preconditioning and postconditioning have been used by clinicians to overcome ischemia-reperfusion injury. The present review focuses on the clinical applications of different conditioning techniques in diverse pathological conditions of ischemia-reperfusion injury.

The Role of Natriuretic Peptides in the Regulation of Cardiac Tolerance to Ischemia/Reperfusion and Postinfarction Heart Remodeling.

In the past 10 years, mortality from acute myocardial infarction has not decreased despite the widespread introduction of percutaneous coronary intervention. The reason for this situation is the absence in clinical practice of drugs capable of preventing reperfusion injury of the heart with high efficiency. In this regard, noteworthy natriuretic peptides (NPs) which have the infarct-limiting effect, prevent reperfusion cardiac injury, prevent adverse post-infarction remodeling of the heart. Atrial natriuretic peptide does not have the infarct-reducing effect in rats with alloxan-induced diabetes mellitus. NPs have the anti-apoptotic and anti-inflammatory effects. There is indirect evidence that NPs inhibit pyroptosis and autophagy. Published data indicate that NPs inhibit reactive oxygen species production in cardiomyocytes, aorta, heart, kidney and the endothelial cells. NPs can suppress aldosterone, angiotensin II, endothelin-1 synthesize and secretion. NPs inhibit the effects aldosterone, angiotensin II on the post-receptor level through intracellular signaling events. NPs activate guanylyl cyclase, protein kinase G and protein kinase A, and reduce phosphodiesterase 3 activity. NO-synthase and soluble guanylyl cyclase are involved in the cardioprotective effect of NPs. The cardioprotective effect of natriuretic peptides is mediated via activation of kinases (AMPK, PKC, PI3 K, ERK1/2, p70s6 k, Akt) and inhibition of glycogen synthase kinase 3ß. The cardioprotective effect of NPs is mediated via sarcolemmal KATP channel and mitochondrial KATP channel opening. The cardioprotective effect of brain natriuretic peptide is mediated via MPT pore closing. The anti-fibrotic effect of NPs may be mediated through inhibition TGF-ß1 expression. Natriuretic peptides can inhibit NF-κB activity and activate GATA. Hemeoxygenase-1 and peroxisome proliferator-activated receptor γ may be involved in the infarct-reducing effect of NPs. NPs exhibit the infarct-limiting effect in patients with acute myocardial infarction. NPs prevent post-infarction remodeling of the heart. To finally resolve the question of the feasibility of using NPs in AMI, a multicenter, randomized, blind, placebo-controlled study is needed to assess the effect of NPs on the mortality of patients after AMI.

Protective effects of caspase-9 and poly(ADP-ribose) polymerase inhibitors on ischemia-reperfusion-induced myocardial injury.

The present study was designed to investigate the cardio-protective effect of Ac-LEDH-cmk a selective caspase-9 inhibitor and 5-aminoisoquinolinone a selective Poly (ADP-ribose) polymerase inhibitor on ischemia and reperfusion induced apoptotic and necrotic cell death in rats. Isolated rat hearts were exposed to 30 minutes of global ischemia followed by 120 minutes of reperfusion using Langendorff's apparatus. Myocardial injury was assessed in the terms of infarct size, release of lactate dehydrogenase, creatine kinase enzymes and apoptotic index was assessed by DNA smearing on agarose gel electrophoresis. Pretreatments with specific inhibitor of caspase-9, Ac-LEHD-cmk (0.07 muM and 0.105 muM), and inhibitor of PARP, 5-aminoisoquinolinone (5 microM and 7.5 muM), significantly attenuated I/R induced increase in infarct size, release of lactate dehydrogenase and creatine kinase in the coronary effluent, and apoptotic index. Therefore, it may be concluded that inhibition of caspase-9 and PARP prevent ischemia and reperfusion-induced activation of apoptotic cascade and necrosis in rat myocardium.

Studies on cerebral protection of digoxin against ischemia/reperfusion injury in mice.

The present study was designed to investigate the possible neuroprotective effect of digoxin induced pharmacological preconditioning (PP) and its probable mechanism. Bilateral carotid artery occlusion (BCAO) of 17 min followed by reperfusion for 24 h was employed to produce ischemia and reperfusion (I/R) induced cerebral injury in male swiss albino mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was assessed using elevated plus maze test. Degree of motor incoordination was evaluated using inclined beam walking test, rota rod test and lateral push test. Digoxin (0.08 mg/kg, i.p.) was administered 24 h before surgery in a separate group of animals to induce PP. BCAO followed by reperfusion, produced significant rise in cerebral infarct size along with impairment of memory and motor coordination. Digoxin treatment produced a significant decrease in cerebral infarct size and reversal of I/R induced impairment of memory and motor incoordination. Digoxin induced neuroprotective effect was abolished significantly by verapamil (15 mg/kg, i.p.), a L-type calcium channel blocker, ruthenium red (3 mg/kg, s.c.), an intracellular ryanodine receptor blocker and 3,4-dichlorobenzamil (Na(+)/Ca(2+) exchanger inhibitor). These findings indicate that digoxin preconditioning exerts a marked neuroprotective effect on the ischemic brain, which is possibly linked to digitalis induced increase in intracellular calcium levels eventually leading to the activation of calcium sensitive signal transduction cascades.

Physiological and Pathological Role of TRPV1, TRPV2 and TRPV4 Channels in Heart.

Transient receptor potential vanilloid channel 2 (TRPV2) is required for normal cardiac contractility. The stimulation of TRPV1 in isolated cardiomyocytes can aggravate the effect of hypoxia/ reoxygenation (H/R) on H9C2 cells. The knockout of the TRPV1 gene promotes increased tolerance of the isolated perfused heart to the impact of ischemia/reperfusion (I/R). However, activation of TRPV1 increases the resistance of the heart to I/R due to calcitonin gene-related peptide (CGRP) release from afferent nerve endings. It has been established that TRPV1 and TRPV2 are involved in the pathogenesis of myocardial infarction and, in all likelihood, ensure the cardiac tolerance to the ischemia/reperfusion. It has also been documented that the activation of TRPV4 negatively affects the stability of cardiomyocytes to the H/R. The blockade of TRPV4 can be considered as a new approach to the prevention of I/R injury of the heart. Studies also indicate that TRPV1 is involved in the pathogenesis of cardiac hypertrophy and that TRPV2 channels participate in the pathogenesis of dilated cardiomyopathy. Excessive expression of TRPV2 leads to chronic Ca2+- overload of cardiomyocytes, which may contribute to the development of cardiomyopathy.

Ameliorative role of Atorvastatin and Pitavastatin in L-Methionine induced vascular dementia in rats.

BACKGROUND: Statins, HMG-CoA reductase inhibitors, are widely prescribed drugs for dyslipidemias. Recent studies have indicated number of cholesterol independent actions of statins including their beneficial effects on vascular endothelial dysfunction and memory deficits associated with dementia of Alzheimer's type. However the potential of statins in dementia of vascular origin still remains to be explored. Therefore, the present study has been designed to investigate the effect of Atorvastatin & Pitavastatin on vascular endothelial dysfunction associated memory deficits in rats. In this study L-Methionine induced vascular dementia was assessed by Morris water-maze (MWM) test. Biochemical analysis was also performed to unfold possible mechanism of statins mediated modulation of vascular dementia. RESULTS: L-Methionine produced endothelial dysfunction as reflected by significant decrease in serum nitrite concentration. L-Methionine treated rats performed poorly on MWM indicating impairment of memory as well. These rats also showed a significant rise in brain oxidative stress, acetylcholinesterase (AChE) activity and serum total cholesterol levels. Both Atorvastatin as well as Pitavastatin attenuated L-Methionine induced endothelial dysfunction associated memory deficits. Statins also reversed L-Methionine induced rise in brain oxidative stress, AChE activity and serum cholesterol. CONCLUSION: The beneficial effects of statins may be attributed to their multiple effects and the study highlights the potential of these drugs in vascular dementia.

Pharmacological preconditioning of the brain: a possible interplay between opioid and calcitonin gene related peptide transduction systems.

The present study has been undertaken to investigate the possible link between calcitonin gene related peptide (CGRP) and opioid receptor transduction systems in the neuroprotective mechanism of pharmacological preconditioning. Occlusion of the bilateral carotid artery for 17 min, followed by reperfusion for 24 h, was employed to produce ischemia and reperfusion (I/R) induced cerebral injury in mice. Cerebral infarct size was measured by using triphenyltetrazolium chloride staining. Memory was assessed using the Morris water maze (MWM) test. Degree of motor incoordination was evaluated using the inclined beam walk test, rota-rod test, and lateral push test. Morphine (8 mg/kg, ip), an opioid agonist, and capsaicin (0.1 mg/kg, iv), a CGRP releasing agent, were administered 24 h before surgery to separate groups of animals to induce pharmacological preconditioning. Bilateral carotid artery occlusion, followed by reperfusion, produced a significant increase in the cerebral infarct size and impaired memory as well as motor coordination. Morphine and capsaicin treatment produced both a significant decrease in the cerebral infarct size and a reversal of I/R-induced impairment of memory and motor-coordination. Morphine-induced (8 mg/kg, ip) neuroprotective effects were completely decreased by sumatriptan (8 mg/kg, ip, a CGRPrelease inhibitor) administered 1 h before and 6 h and 12 h after morphine administration. Capsaicin-induced neuroprotection was decreased by naloxone (5 mg/kg, ip, an opioid antagonist) administered 1 h before and 6 h and 12 h after capsaicin administration. These findings indicate that the transduction systems mediating morphine- and capsaicin-induced pharmacological preconditioning in brain are possibly interlinked with one another.

Reduction of ischemic, pharmacological and remote preconditioning effects by an antioxidant N-acetyl cysteine pretreatment in isolated rat heart.

The present study was designed to investigate the possible role of free radicals in cardioprotective effects of ischemic, pharmacological and remote preconditioning. Isolated rat heart was perfused on Langendorff apparatus with Kreb's Henseleit solution and subjected to 30 min global ischemia followed by 120 min reperfusion. To assess myocardial injury, coronary effluent was analyzed for lactate dehydrogenase and creatine kinase activity. Myocardial infarct size was estimated using triphenyl tetrazolium chloride staining. Ischemic preconditioning, pharmacological preconditioning (angiotensin II; H2O2), remote aortic preconditioning markedly attenuated I/R induced increase in lactate dehydrogenase and creatine kinase release and myocardial infarct size. Administration of N-Acetyl Cysteine (NAC), in vitro, during ischemic and pharmacological, and in vivo during remote preconditioning attenuated the cardioprotective effects of preconditioning. On the basis of these results, it may be concluded that sub threshold generation of Reactive Oxygen Species (ROS) may activate redox signaling which may be responsible for preconditioning induced cardioprotection.

Potential of carnosine, a histamine precursor in rat model of bilateral common carotid artery occlusion-induced vascular dementia.

The present study investigates the potential of Carnosine, a histamine precursor in rat model of bilateral common carotid artery occlusion (BCCAo)-induced vascular dementia (VaD). Wistar rats were subjected to BCCAo procedure under anaesthesia to induce VaD. The rats were subjected to Morris water maze (MWM) test (6th day onwards post-surgery). MWM test was employed to assess learning and memory of the animals whereby escape latency time, time spent in target quadrant and Path length (distance travelled) taken as important parameters. Serum nitrite level; Brain thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) levels; Brain acetylcholinesterase (AChE) activity; brain Myeloperoxidase activity (MPO) and neutrophil count were estimated as per standard procedures. BCCAo in rats produced a significant vascular endothelial dysfunction, as reflected by decrease in serum nitrite levels. Further, these animals showed poor performance on MWM, depicting impairment of learning and memory. There was a significant rise in brain oxidative stress level as indicated by increase in TBARS and decrease in GSH levels. An increase in brain AChE activity was also observed. Moreover, these rats also exhibited an increase in MPO activity and neutrophil infiltration in brain (as marker of inflammation). Treatment of Carnosine (200 and 400 mg/kg, i.p.)/Donepezil (0.3 mg/kg, i.p.) ameliorated BCCAo-induced memory deficits; endothelial dysfunction; biochemical and histopathological changes. It is concluded that Carnosine has shown efficacy in rat model of BCCAo-induced VaD and can be considered as an important therapeutic agent for the treatment of VaD.

Investigating the possible mechanisms involved in adenosine preconditioning-induced cardioprotection in rats.

BACKGROUND: Adenosine is a breakdown product of adenosine triphosphate and plays an important role in pharmacological preconditioning. The cardioprotective effects of adenosine preconditioning are well established. However, the possible mechanisms need to be explored. AIM: This study was aimed to investigate the possible mechanisms involved in adenosine preconditioning-induced cardioprotection in rats. METHODS: Rat heart was isolated and perfused on Langendorff apparatus. Global ischemia for 30 minutes followed by reperfusion for 120 minutes was employed to produce myocardial injury. Myocardial injury was assessed by measuring myocardial infarct size, release of lactate dehydrogenase (LDH) and creatine kinase (CK) in the coronary effluent and hemodynamic parameters including left ventricular developed pressure (LVDP), dp/dtmax, and dp/dtmin . Serum nitrite levels were measured as an index of nitric oxide release in blood. RESULTS: Adenosine (4 mg/kg) preconditioning significantly decreased ischemia-reperfusion-induced increase in LDH, CK release, infarct size, improved LVDP, dp/dtmax and dp/dtmin, and increased serum nitrite levels. Pretreatment with L-NAME, a specific NOS inhibitor, (5 mg/kg) and montelukast, leukotriene receptor antagonist, (10 mg/kg) significantly abrogated the cardioprotective effect of adenosine preconditioning. However, seratrodast, thromboxane A2 antagonist, (15 mg/kg) had no effect on adenosine-induced cardioprotection. Sodium nitroprusside (SNP) preconditioning also produced cardioprotective effects. However, caffeine (20 mg/kg) (adenosine receptor blocker) and seratrodast (15 mg/kg) had no effect on SNP-induced cardioprotection. Administration of montelukast abrogated the cardioprotective effects of SNP preconditioning-induced cardioprotection. CONCLUSION: Adenosine preconditioning may increase the release of nitric oxide, which in turn may increase the release of cysteinyl leukotrienes to confer cardioprotection.

Reactive Oxygen Species as Intracellular Signaling Molecules in the Cardiovascular System.

BACKGROUND: Redox signaling plays an important role in the lives of cells. This signaling not only becomes apparent in pathologies but is also thought to be involved in maintaining physiological homeostasis. Reactive Oxygen Species (ROS) can activate protein kinases: CaMKII, PKG, PKA, ERK, PI3K, Akt, PKC, PDK, JNK, p38. It is unclear whether it is a direct interaction of ROS with these kinases or whether their activation is a consequence of inhibition of phosphatases. ROS have a biphasic effect on the transport of Ca2+ in the cell: on one hand, they activate the sarcoplasmic reticulum Ca2+-ATPase, which can reduce the level of Ca2+ in the cell, and on the other hand, they can inactivate Ca2+-ATPase of the plasma membrane and open the cation channels TRPM2, which promote Ca2+-loading and subsequent apoptosis. ROS inhibit the enzyme PHD2, which leads to the stabilization of HIF-α and the formation of the active transcription factor HIF. CONCLUSION: Activation of STAT3 and STAT5, induced by cytokines or growth factors, may include activation of NADPH oxidase and enhancement of ROS production. Normal physiological production of ROS under the action of cytokines activates the JAK/STAT while excessive ROS production leads to their inhibition. ROS cause the activation of the transcription factor NF-κB. Physiological levels of ROS control cell proliferation and angiogenesis. ROS signaling is also involved in beneficial adaptations to survive ischemia and hypoxia, while further increases in ROS can trigger programmed cell death by the mechanism of apoptosis or autophagy. ROS formation in the myocardium can be reduced by moderate exercise.

Amniotic fluid derived stem cells ameliorate focal cerebral ischaemia-reperfusion injury induced behavioural deficits in mice.

The present study has been designed to investigate the effect of amniotic fluid derived stem cells on focal cerebral ischaemia-reperfusion injury induced behavioural deficits in mice. Middle cerebral artery occlusion of 60 min followed by reperfusion for 7 days was employed in present study to produce ischaemia and reperfusion induced cerebral injury in mice. Assessment of cognitive behaviour was done using elevated plus maze. Assessment of neurological severity score was employed to assess motor, sensory, reflex, and balance tests in a composite manner. Adhesive-removal somatosensory test was employed to evaluate somatosensory deficit. Partial occlusion of middle cerebral artery markedly impaired memory, motor coordination, sensorimotor ability and somatosensory functions as inferred from the results of elevated plus-maze test, adhesive-removal test and neurological severity score test. Intracerebroventricular administration of amniotic fluid derived stem cells/embryonic neuronal stem cells significantly reversed the focal cerebral ischaemia-reperfusion induced behavioural deficit measured in terms of loss of short-term memory, motor coordination, sensorimotor ability and somatosensory functions. Therefore, it may be concluded that stem cells derived from amniotic fluid exert beneficial effect on the ischaemic brain to an extent comparable to the neuroprotective effect of embryonic neuronal stem cells.