Doxorubicin-induced behavioral disturbances in rats: Protective effect of melatonin and captopril

The Distant Molecular Effects on the Brain by Cancer Treatment

Cancer survivors experience cancer-related cognitive impairment (CRCI) secondary to treatment. Chemotherapy and radiation therapy independently contribute to cognitive dysfunction; however, the underlying mechanisms leading to dysfunction remain unclear. We characterized brain gene expression changes in a mouse model of CRCI to identify the mechanistic underpinnings. Eleven-to-twelve-week-old SKH1 mice were treated with doxorubicin (DOX), hindlimb radiation (RT), concurrent hindlimb radiation and doxorubicin (DOX-RT), or no treatment (control). Sixteen days following treatment, gene expression was measured from murine brains using the NanoString nCounter® glial profiling panel. Gene expression was normalized and compared between groups. No two groups shared the same expression pattern, and only Gnb1 and Srpr were upregulated in multiple treatment groups. Brains from DOX-treated mice had upregulated Atf2, Atp5b, Gnb1, Rad23b, and Srpr and downregulated Sirt5 expression compared to control brains. Brains from RT-treated mice demonstrated increased Abcg2 and Fgf2 and decreased C1qa and C1qb expression compared to control brains. Brains from DOX-RT-treated mice had upregulated Adar, E2f3, Erlec1, Gnb1, Srpr, Vim, and Pdgfra expression and downregulated Rock2 and Inpp5f expression compared to control brains. The gene expression changes demonstrated here highlight roles for neuronal transmission and oxidative stress in the pathogenesis of doxorubicin-related CRCI and inflammation in RT-related CRCI.

A Review on the Neurotoxic Effects of Doxorubicin

Anthracyclines, a class of drugs considered as most effective anticancer drugs, used in the various regimens of cancer chemotherapy, induce long-term impairment of mitochondrial respiration, increase reactive oxygen species, and induce other mechanisms potentially leading to neurotoxicity. According to literature findings, one drug of this class - doxorubicin used to treat e.g. breast cancer, bladder cancer, lymphoma, and acute lymphocytic leukemia may induce such effects in the nervous system. Doxorubicin has poor penetration into the brain due to the lack of drug penetration through the blood-brain barrier, thus the toxicity of this agent is the result of its peripheral action. This action is manifested by cognitive impairment and anatomical changes in the brain and peripheral nervous system found in both preclinical and clinical studies in adult patients. Furthermore, more than 50% of children with cancer are treated with anthracyclines including doxorubicin, which may affect their nervous system, and lead to lifelong damage in many areas of their life. Despite ongoing research into the side effects of this drug, the mechanism of its neurotoxicity action on the central and peripheral nervous system is still not well understood. This review aims to summarize the neurotoxic effects of doxorubicin in preclinical (in vitro and in vivo) research and in clinical studies. Furthermore, it discusses the possible mechanisms of the toxic action of this agent on the nervous system.

Age-related decline in hippocampal tyrosine phosphatase PTPRO is a mechanistic factor in chemotherapy-related cognitive impairment

Chemotherapy-related cognitive impairment (CRCI) or "chemo brain" is a devastating neurotoxic sequela of cancer-related treatments, especially for the elderly individuals. Here we show that PTPRO, a tyrosine phosphatase, is highly enriched in the hippocampus, and its level is tightly associated with neurocognitive function but declined significantly during aging. To understand the protective role of PTPRO in CRCI, a mouse model was generated by treating Ptpro-/- female mice with doxorubicin (DOX) because Ptpro-/- female mice are more vulnerable to DOX, showing cognitive impairments and neurodegeneration. By analyzing PTPRO substrates that are neurocognition-associated tyrosine kinases, we found that SRC and EPHA4 are highly phosphorylated/activated in the hippocampi of Ptpro-/- female mice, with increased sensitivity to DOX-induced CRCI. On the other hand, restoration of PTPRO in the hippocampal CA3 region significantly ameliorate CRCI in Ptpro-/- female mice. In addition, we found that the plant alkaloid berberine (BBR) is capable of ameliorating CRCI in aged female mice by upregulating hippocampal PTPRO. Mechanistically, BBR upregulates PTPRO by downregulating miR-25-3p, which directly targeted PTPRO. These findings collectively demonstrate the protective role of hippocampal PTPRO against CRCI.

Curcumin protects against doxorubicin induced oxidative stress by regulating the Keap1-Nrf2-ARE and autophagy signaling pathways

BACKGROUND

Doxorubicin (DOX)-induced neurotoxicity is widely reported in previous studies. Oxidative stress has been validated as a critical event involved in DOX-induced neurotoxicity. As a selective autophagy adaptor protein, p62 is reported to regulate Keap1-Nrf2-ARE antioxidant pathway in response to oxidative stress. Curcumin (CUR) relieves depressive-like state through the mitigation of oxidative stress and the activation of Nrf2-ARE signaling pathway. However, the exact mechanism of CUR in alleviating DOX-induced neurotoxicity is still unknown.

MATERIALS AND METHODS

The rats were randomly divided into three groups: control group, DOX group, and DOX + CUR group. At the end of 3 weeks, the behavior tests as sucrose preference test (SPT), forced swimming test (FST), and novelty-suppressed feeding test (NSFT) were performed to assess anxiety- and depression-like behaviors. The rats were sacrificed after behavior tests, and the brain tissues were collected for biochemical analysis.

RESULTS

It was observed that the administration of CUR could effectively reverse DOX-induced depressive-like behaviors. The exposure of DOX activated autophagy and increased oxidative stress levels, and the administration of CUR could significantly inhibit DOX-induced autophagy and suppress oxidative stress. More importantly, we also found that Keap1-Nrf2-ARE signaling pathway was involved in DOX-induced neurotoxicity and oxidative stress regulated by autophagy.

CONCLUSION

Our study demonstrated that CUR could effectively reverse DOX-induced neurotoxicity through suppressing autophagy and mitigating oxidative stress and endoplasmic reticulum (ER) stress.

Cancer treatment induces neuroinflammation and behavioral deficits in mice

Introduction: Cancer survivors are increasingly diagnosed with a syndrome of neurocognitive dysfunction termed cancer-related cognitive impairment (CRCI). Chemotherapy and radiation therapy have been implicated in CRCI; however, its underlying pathogenesis remains unclear, hindering effective prevention or treatment. Methods: We used the hairless strain SKH1 (11-12-week-old) and treated the mice with radiation to the right hindlimb, doxorubicin (a chemotherapy agent), concurrent radiation, and doxorubicin, or no treatment (control). Neurocognition was evaluated via standardized behavioral testing following treatment. Mice were subsequently humanely euthanized, and plasma and brains were collected to identify inflammatory changes. Results: Mice treated with radiation, doxorubicin, or both radiation and doxorubicin demonstrated equivalent hippocampal dependent memory deficits and significant increases in activated microglia and astrocytes compared to control mice. Doxorubicin-treated mice had significantly increased plasma IL-6 and failed to gain weight compared to control mice over the study period. Discussion: This study demonstrates that non-brain directed radiation induces both gliosis and neurocognitive deficits. Moreover, this work presents the first characterization of SKH1 mice as a relevant and facile animal model of CRCI. This study provides a platform from which to build further studies to identify potential key targets that contribute to CRCI such that strategies can be developed to mitigate unintended neuropathologic consequences associated with anticancer treatment.

Melatonin as a Potential Approach to Anxiety Treatment

Anxiety disorders are the most common mental diseases. Anxiety and the associated physical symptoms may disturb social and occupational life and increase the risk of somatic diseases. The pathophysiology of anxiety development is complex and involves alterations in stress hormone production, neurosignaling pathways or free radical production. The various manifestations of anxiety, its complex pathophysiological background and the side effects of available treatments underlie the quest for constantly seeking therapies for these conditions. Melatonin, an indolamine produced in the pineal gland and released into the blood on a nightly basis, has been demonstrated to exert anxiolytic action in animal experiments and different clinical conditions. This hormone influences a number of physiological actions either via specific melatonin receptors or by receptor-independent pleiotropic effects. The underlying pathomechanism of melatonin's benefit in anxiety may reside in its sympatholytic action, interaction with the renin-angiotensin and glucocorticoid systems, modulation of interneuronal signaling and its extraordinary antioxidant and radical scavenging nature. Of importance, the concentration of this indolamine is significantly higher in cerebrospinal fluid than in the blood. Thus, ensuring sufficient melatonin production by reducing light pollution, which suppresses melatonin levels, may represent an endogenous neuroprotective and anxiolytic treatment. Since melatonin is freely available, economically undemanding and has limited side effects, it may be considered an additional or alternative treatment for various conditions associated with anxiety.

Hypotensive effects of melatonin in rats: Focus on the model, measurement, application, and main mechanisms

The hypotensive effects of melatonin are based on a negative correlation between melatonin levels and blood pressure in humans. However, there is a positive correlation in nocturnal animals that are often used as experimental models in cardiovascular research, and the hypotensive effects and mechanism of melatonin action are often investigated in rats and mice. In rats, the hypotensive effects of melatonin have been studied in normotensive and spontaneously or experimentally induced hypertensive strains. In experimental animals, blood pressure is often measured indirectly during the light (passive) phase of the day by tail-cuff plethysmography, which has limitations regarding data quality and animal well-being compared to telemetry. Melatonin is administered to rats in drinking water, subcutaneously, intraperitoneally, or microinjected into specific brain areas at different times. Experimental data show that the hypotensive effects of melatonin depend on the experimental animal model, blood pressure measurement technique, and the route, time and duration of melatonin administration. The hypotensive effects of melatonin may be mediated through specific membrane G-coupled receptors located in the heart and arteries. Due to melatonin's lipophilic nature, its potential hypotensive effects can interfere with various regulatory mechanisms, such as nitric oxide and reactive oxygen species production and activation of the autonomic nervous and circadian systems. Based on the research conducted on rats, the cardiovascular effects of melatonin are modulatory, delayed, and indirect.

Cardiovascular therapeutics: A new potential for anxiety treatment?

Besides the well‐recognized risk factors, novel conditions increasing cardiovascular morbidity and mortality are emerging. Undesirable emotions and behavior such as anxiety and depression, appear to participate in worsening cardiovascular pathologies. On the other hand, deteriorating conditions of the heart and vasculature result in disturbed mental and emotional health. The pathophysiological background of this bidirectional interplay could reside in an inappropriate activation of vegetative neurohormonal and other humoral systems in both cardiovascular and psychological disturbances. This results in circulus vitiosus potentiating mental and circulatory disorders. Thus, it appears to be of utmost importance to examine the alteration of emotions, cognition, and behavior in cardiovascular patients. In terms of this consideration, recognizing the potential of principal cardiovascular drugs to interact with the mental state in patients with heart or vasculature disturbances is unavoidable, to optimize their therapeutic benefit. In general, beta‐blockers, central sympatholytics, ACE inhibitors, ARBs, aldosterone receptor blockers, sacubitril/valsartan, and fibrates are considered to exert anxiolytic effect in animal experiments and clinical settings. Statins and some beta‐blockers appear to have an equivocal impact on mood and anxiety and ivabradine expressed neutral psychological impact. It seems reasonable to suppose that the knowledge of a patient's mood, cognition, and behavior, along with applying careful consideration of the choice of the particular cardiovascular drug and respecting its potential psychological benefit or harm might improve the individualized approach to the treatment of cardiovascular disorders.

Potential Protective Effect of Coenzyme Q10 on Doxorubicin-Induced Neurotoxicity and Behavioral Disturbances in Rats

The aim of this study was to investigate the potential neuroprotective efficacy of coenzyme Q10 (CoQ10) against doxorubicin (DOX) -induced behavioral disturbances in rats. Female rats were randomly assigned into 4 groups as control, CoQ10, DOX, and DOX plus CoQ10. The CoQ10 groups received CoQ10 (200 mg kg^-1) for 21 days, and the DOX groups received DOX (4 mg kg^-1) on days 7 and 14 of the study. The open field (OF) and elevated plus maze (EPM) tests were performed to assess locomotor activity and anxiety levels. Additionally, malondialdehyde (MDA), and protein carbonyl (PC) levels and acetylcholinesterase (AChE), and glutathione peroxidase (GPx) activities and total antioxidant capacity (TAC) were quantified in brain tissue. DOX administration caused alterations in locomotor activity, and anxiety-like behaviors. Moreover, DOX produced significant elevation in AChE activity . PC level and GPx activity tended to alter with DOX administration. Co-treatment with CoQ10 significantly attenuated DOX-induced behavioral alterations via improving AChE activity in the brain tissue of rats. CoQ10 treatment may be potential for the alleviation of DOX-induced behavioral disturbances. This improvement might be due to the inhibition of AChE activity.

Comparing the Effects of Melatonin and Zolpidem on Mental Health and Sexual Function in Men With Opioid Addiction: Evidence From a Randomized Clinical Trial

BACKGROUND

Mental health problems and impaired sexual function are widely reported among those suffering from drug abuse, particularly among those under methadone maintenance therapy (MMT).

AIMS

The current study aimed to, firstly, investigate the effect of melatonin and zolpidem on mental health and sexual function of those with drug abuse under MMT, and, secondly, to compare the effects of melatonin and zolpidem on the studied outcomes.

METHODS

The current randomized, single-blind, placebo-controlled clinical trial was conducted on 98 participants who were randomly assigned into three groups of melatonin (n = 34), zolpidem (n = 32), and placebo (n = 32). All participants received the intervention once a day for 30 days, without changes in nutrition. Mental health and sexual function were measured before and 30 days after the intervention.

RESULTS

The mean age of participants in the groups of melatonin, zolpidem, and placebo was 35.8 ± 9.6 years (22-58 years of old), 35.9 ± 9.3 years (21-58), and 37.2 ± 7.8 years (26-53), respectively. Sexual function mean score was significantly increased from 38 to 41 in the melatonin group, while it deceased in zolpidem (from 39.1 to 38) and placebo (39.25-38.59) groups. Also, mental health mean scores improved statistically significantly in the melatonin group (from 60.65 to 43.56; p = 0.002), and descriptively in the zolpidem group (57.88-51.18; p = 0.129). Concerning both outcomes, the observed improvement was considerably higher in the melatonin group. The highest improvement was observed in dimensions of overall satisfaction and depression in the melatonin group (1.18 and -8.4, respectively).

CONCLUSION

Melatonin could significantly improve both mental health and some domains of sexual function of those with drug abuse under MMT, while zolpidem did not show a significant effect.

TRIAL REGISTRATION NUMBER

https://www.irct.ir/trial/53047, identifier: IRCT20201214049718N1.

Behavioral and morphological effects of resveratrol and curcumin in rats submitted to doxorubicin-induced cognitive impairment

Doxorubicin (DOX) is known to cause cognitive impairments in patients submitted to long-term chemotherapy (deficits also known as chemobrain). Therefore, there is an urgent need for therapeutic strategies capable of returning cancer survivors back to their previous quality of life. The present study investigated whether resveratrol (RSV) or curcumin (CUR) administration could affect mnemonic function and brain morphological changes following DOX administration in rats. Male Wistar rats were divided into 4 groups: DOX group (2.5 mg/kg/week for 4 weeks, i.p., plus distilled water for 28 days, oral gavage - OG), DOX + RSV group (DOX, 2.5 mg/kg/week for 4 weeks, i.p., plus RSV, 10 mg/kg/day for 28 days, OG), DOX + CUR group (DOX, 2.5 mg/kg/week for 4 weeks, i.p., plus CUR, 100 mg/kg/day for 28 days, OG) and control (CTR) group (0.9% saline solution weekly for 4 weeks, i.p., plus distilled water for 28 days, OG). Behavioral analyses (open field - OF - and the novel object recognition test - NORT) were performed. Brains were collected and analyzed by hematoxylin-eosin and luxol fast blue staining techniques and by immunohistochemistry for GFAP (glial fibrillary acidic protein) expression in astrocytes and Iba1 (ionized calcium-binding adaptor molecule 1) expression in microglia. DOX-injected rats presented short-term and long-term memory impairments as seen in the NORT at 3 and 24 h after habituation and increased GFAP and Iba1 expression, respectively, in astrocytes and microglia of the frontal cortex, hypothalamus and hippocampus. Such cognitive deficits were prevented by CUR at both periods and by RSV at 24 h. DOX-induced astrogliosis and microgliosis were avoided by RSV and CUR. No signs of demyelination or neuronal loss were found in any group. Thus, CUR and RSV prevented memory loss, astrogliosis and microgliosis induced by DOX monotherapy.

Chemobrain in rats: Behavioral, morphological, oxidative and inflammatory effects of doxorubicin administration

Doxorubicin (DOX) is known to cause cognitive impairments in patients submitted to long-term chemotherapy (deficits also known as chemobrain). The present study investigated whether DOX administration could affect behavior and brain morphology, as well as oxidative and inflammatory status in rats. Male Wistar rats were injected with DOX (2.5 mg/kg/week, 4 weeks, i.p.) or saline. Behavioral analyses were performed. Brains were collected and analyzed by hematoxylin-eosin and luxol fast blue staining techniques and by immunohistochemistry (for glial fibrillary acidic protein expression in astrocytes; GFAP). Serum and brain levels of TNF-α, IL-1β, IL-6, IL-8, IL-10 and CXCL-1 were determined. Oxidative parameters, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), nitric oxide (NO•), brain iron and ferritin levels, as well as reduced and oxidized glutathione (GSH and GSSG, respectively) and thiobarbituric acid reactive substances (TBARS) were also assessed in brain. DOX-injected rats presented cognitive/memory impairments, increased GFAP expression, increased levels of TBARS, NO and GR, but decreased GSSG and ferritin levels in brain homogenate. In addition, increased serum and brain levels of IL-6, IL-8 and CXCL1 were noted in the DOX group, although IL-10 decreased. As DOX has a poor penetration across the blood-brain barrier (BBB), it is proposed that this drug elicits a systemic proinflammatory response with increase of proinflammatory cytokines which cross the BBB and can be involved in the induction of oxidative molecules and proinflammatory cytokines that altogether induce astrogliosis all over the brain. These events may be responsable for chemotherapy-induced cognitive/memory deficits.

The effects of melatonin supplementation on mental health, metabolic and genetic profiles in patients under methadone maintenance treatment

This investigation was designed to determine the effect of melatonin supplementation on mental health parameters, metabolic and genetic profiles in patients under methadone maintenance treatment (MMT). This randomized, double-blind, placebo-controlled, clinical trial was conducted among 54 patients under MMT. Participants were randomly allocated to receive either 10 mg melatonin (2 melatonin capsules, 5 mg each) (n = 26) or placebo (n = 28) once a day, 1 hour before bedtime for 12 weeks. Melatonin supplementation significantly decreased Pittsburgh Sleep Quality Index (β -4.08; 95 percent CI, -5.51, -2.65; P < 0.001), Beck Depression Inventory index (β -5.46; 95% CI, -8.92, -2.00; P = 0.003) and Beck Anxiety Inventory index (β -3.87; 95% CI, -5.96, -1.77; P = 0.001) and significantly increased International Index of Erectile Functions (β 5.59; 95% CI, 1.76, 9.42; P = 0.005) compared with the placebo. Subjects who received melatonin supplements had significantly lower serum insulin levels (β -2.53; 95% CI, -4.48, -0.59; P = 0.01), homeostasis model of assessment-insulin resistance (β -0.56; 95% CI, -1.03, -0.09; P = 0.01) and higher quantitative insulin sensitivity check index (β 0.01; 95% CI, 0.004, 0.02; P = 0.009) and HDL-cholesterol levels (β 3.71; 95% CI, 1.77, 5.64; P = 0.002) compared to placebo. Additionally, melatonin intake resulted in a significant reduction in serum high sensitivity C-reactive protein (β -0.15; 95% CI, -0.27, -0.02; P = 0.02), malondialdehyde (β -0.31; 95% CI, -0.57, -0.05; P = 0.02) and protein carbonyl (β -0.06; 95% CI, -0.09, -0.04; P < 0.001). This trial indicated that taking melatonin supplements for 12 weeks by patients under MMT had beneficial effects on their mental health metabolic profiles.

Ivabradine does not impair anxiety-like behavior and memory in both healthy and L-NAME-induced hypertensive rats

Cardiovascular pathologies are frequently associated with anxiety and other behavioral disturbances. Ivabradine, an inhibitor of the hyperpolarization-activated cyclic nucleotide-gated channels in the sinoatrial node, decreases heart rate and provides cardiovascular protection. Although ivabradine is increasingly used in cardiovascular medicine, the data on its behavioral effects are lacking. The aim of this work was to show ivabradine's potential effect on behavior in healthy and hypertensive rats. After a four-week treatment period, systolic blood pressure was increased in the N(G)-nitro-L-arginine methyl ester (L-NAME)-group and ivabradine significantly reduced it. Furthermore, it reduced the heart rate in both the control and L-NAME-group. In the control group, ivabradine enhanced the time spent in and transition to the open arms of the elevated plus maze test (EPM). In the L-NAME-group, ivabradine does not show a significant effect on the time spent in the EPM open arms and the number of transitions into them. Furthermore, ivabradine has no impact on cognitive function in both control and L-NAME groups. We conclude that ivabradine showed no undesirable effects on anxiety, locomotion or learning; in fact, some of these parameters were even improved. For the first time it has been shown that ivabradine is a safe cardiovascular drug regarding its effect on psycho-behavioral manifestations.

The antidepressant effect of melatonin and fluoxetine in diabetic rats is associated with a reduction of the oxidative stress in the prefrontal and hippocampal cortices

In the past few years possible mechanisms that link diabetes and depression have been found. One of these mechanisms is the increase in lipid peroxidation and decrease in antioxidant activity in the hippocampal and prefrontal cortices, which are brain areas involved in mood. The goal of the present study was to evaluate the effect of an antidepressant and of an antioxidant on behavior and oxidative activity in brains of diabetic rats. Rats rendered diabetic after a treatment with streptozotocin (STZ) (60mg/kg) were treated with fluoxetine (15mg/kg), melatonin (10mg/kg), or vehicle for 4 weeks. All animals were tested for signs of depression and anxiety using the elevated plus maze (EPM), open field test (OFT) and the forced swim test (FST). Four groups were compared: (1) normoglycemic, (2) hyperglycemic vehicle treated, and hyperglycemic (3) fluoxetine or (4) melatonin treated rats. On the last day of the study, blood samples were obtained to determine the levels of hemoglobin A1c (HbA1c). Also, brain samples were collected to measure the oxidative stress in the hippocampal and prefrontal cortices using the thiobarbituric acid reactive substances (TBARS) assay. The activity of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPx), and glutathione S-transferase (GST) were also measured on the brain samples. The results show that both fluoxetine and melatonin decrease the signs of depression and anxiety in all tests. Concomitantly, the levels of HbA1c were reduced in drug treated rats, and to a greater degree in the fluoxetine group. In the cerebral cortex of diabetic rats, TBARS was increased, while the activity of CAT, GPx and GST were decreased. Fluoxetine and melatonin treatments decreased TBARS in both cortices. In the prefrontal cortex, fluoxetine and melatonin restored the activity of CAT, while only melatonin improved the activity of GPx and GST. In the hippocampus, the activity of GPx alone was restored by melatonin, while fluoxetine had no effect. These results suggest that antidepressants and antioxidants can counter the mood and oxidative disorders associated with diabetes. While these effects could result from a decreased production of reactive oxygen species (ROS) remains to be established.

Blood pressure regulation in stress: focus on nitric oxide-dependent mechanisms

Stress is considered a risk factor associated with the development of various civilization diseases including cardiovascular diseases, malignant tumors and mental disorders. Research investigating mechanisms involved in stress-induced hypertension have attracted much attention of physicians and researchers, however, there are still ambiguous results concerning a causal relationship between stress and long-term elevation of blood pressure (BP). Several studies have observed that mechanisms involved in the development of stress-induced hypertension include increased activity of sympathetic nervous system (SNS), glucocorticoid (GC) overload and altered endothelial function including decreased nitric oxide (NO) bioavailability. Nitric oxide is well known neurotransmitter, neuromodulator and vasodilator involved in regulation of neuroendocrine mechanisms and cardiovascular responses to stressors. Thus NO plays a crucial role in the regulation of the stress systems and thereby in the BP regulation in stress. Elevated NO synthesis, especially in the initial phase of stress, may be considered a stress-limiting mechanism, facilitating the recovery from stress to the resting levels via attenuation of both GC release and SNS activity as well as by increased NO-dependent vasorelaxation. On the other hand, reduced levels of NO were observed in the later phases of stress and in subjects with genetic predisposition to hypertension, irrespectively, in which reduced NO bioavailability may account for disruption of NO-mediated BP regulatory mechanisms and accentuated SNS and GC effects. This review summarizes current knowledge on the role of stress in development of hypertension with a special focus on the interactions among NO and other biological systems affecting blood pressure and vascular function.

Angiotensin A/Alamandine/MrgD Axis: Another Clue to Understanding Cardiovascular Pathophysiology

The renin-angiotensin system (RAS) plays a crucial role in cardiovascular regulations and its modulation is a challenging target for the vast majority of cardioprotective strategies. However, many biological effects of these drugs cannot be explained by the known mode of action. Our comprehension of the RAS is thus far from complete. The RAS represents an ingenious system of "checks and balances". It incorporates vasoconstrictive, pro-proliferative, and pro-inflammatory compounds on one hand and molecules with opposing action on the other hand. The list of these molecules is still not definitive because new biological properties can be achieved by minor alteration of the molecular structure. The angiotensin A/alamandine-MrgD cascade associates the deleterious and protective branches of the RAS. Its identification provided a novel clue to the understanding of the RAS. Angiotensin A (Ang A) is positioned at the "crossroad" in this system since it either elicits direct vasoconstrictive and pro-proliferative actions or it is further metabolized to alamandine, triggering opposing effects. Alamandine, the central molecule of this cascade, can be generated both from the "deleterious" Ang A as well as from the "protective" angiotensin 1-7. This pathway modulates peripheral and central blood pressure regulation and cardiovascular remodeling. Further research will elucidate its interactions in cardiovascular pathophysiology and its possible therapeutic implications.

Long Chain Omega-3 Polyunsaturated Fatty Acid Supplementation Alleviates Doxorubicin-Induced Depressive-Like Behaviors and Neurotoxicity in Rats: Involvement of Oxidative Stress and Neuroinflammation

Doxorubicin (DOX) is a chemotherapeutic agent widely used in human malignancies. Its long-term use can cause neurobiological side-effects associated with depression. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs), the essential fatty acids found in fish oil, possess neuroprotecitve and antidepressant activities. Thus, the aim of this study was to explore the potential protective effects of ω-3 PUFAs against DOX-induced behavioral changes and neurotoxicity. ω-3 PUFAs were given daily by gavage (1.5 g/kg) over three weeks starting seven days before DOX administration (2.5 mg/kg). Open-field test (OFT) and forced swimming test (FST) were conducted to assess exploratory activity and despair behavior, respectively. Our data showed that ω-3 PUFAs supplementation significantly mitigated the behavioral changes induced by DOX. ω-3 PUFAs pretreatment also alleviated the DOX-induced neural apoptosis. Meanwhile, ω-3 PUFAs treatment ameliorated DOX-induced oxidative stress in the prefrontal cortex and hippocampus. Additionally, gene expression of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α, and the protein levels of NF-κB and iNOS were significantly increased in brain tissues of DOX-treated group, whereas ω-3 PUFAs supplementation significantly attenuated DOX-induced neuroinflammation. In conclusion, ω-3 PUFAs can effectively protect against DOX-induced depressive-like behaviors, and the mechanisms underlying the neuroprotective effect are potentially associated with its anti-oxidant, anti-inflammatory, and anti-apoptotic properties.

Melatonin Prevents Mitochondrial Damage Induced by Doxorubicin in Mouse Fibroblasts Through Ampk-Ppar Gamma-Dependent Mechanisms

BACKGROUND Doxorubicin (brand name: Adriamycin®) is used to treat solid tissue cancer but it also affects noncancerous tissues. Its mechanism of cytotoxicity is probably related to increased oxidation, mitochondrial dysfunction, and apoptosis. Melatonin is reported to have antiapoptotic and antioxidative effects. The aim of this study was to determine whether melatonin would counteract in vitro cytotoxicity of doxorubicin in mouse fibroblasts and determine the pathway of its action against doxorubicin-induced apoptosis. MATERIAL AND METHODS We measured markers of apoptosis (cytochrome-c, mitochondrial membrane potential, and apoptotic cell number) and oxidative stress (total oxidant and antioxidant status) and calculated oxidant stress index in 4 groups of fibroblasts: controls, melatonin-treated, doxorubicin-treated, and fibroblasts concomittantly treated with a combination of melatonin and doxorubicin. RESULTS Melatonin given with doxorubicin succesfully countered apoptosis generated by doxorubicin alone, which points to its potential as a protective agent against cell death in doxorubicin chemotherapy. This also implies that patients should be receiving doxorubicin treatment when their physiological level of melatonin is at its highest, which is early in the morning. CONCLUSIONS This physiological level may not be high enough to overcome doxorubicin-induced oxidative stress, but adjuvant melatonin treatment may improve quality of life. Further research is needed to verify our findings.

Doxorubicin: Comparison between 3-h continuous and bolus intravenous administration paradigms on cardio-renal axis, mitochondrial sphingolipids and pathology

Doxorubicin (DOX) is a potent and effective broad-spectrum anthracycline antitumor agent, but its clinical usefulness is restricted by cardiotoxicity. This study compared pharmacokinetic, functional, structural and biochemical effects of single dose DOX bolus or 3-h continuous iv infusion (3-h iv) in the Han–Wistar rat to characterize possible treatment-related differences in drug safety over a 72 h observation period. Both DOX dosing paradigms significantly altered blood pressure, core body temperature and QA interval (indirect measure of cardiac contractility); however, there was no recovery observed in the bolus iv treatment group. Following the 3-h iv treatment, blood pressures and QA interval normalized by 36 h then rose above baseline levels over 72 h. Both treatments induced biphasic changes in heart rate with initial increases followed by sustained decreases. Cardiac injury biomarkers in plasma were elevated only in the bolus iv treatment group. Tissue cardiac injury biomarkers, cardiac mitochondrial complexes I, III and V and cardiac mitochondrial sphingolipids were decreased only in the bolus iv treatment group. Results indicate that each DOX dosing paradigm deregulates sinus rhythm.However, slowing the rate of infusion allows for functional compensation of blood pressure and may decrease the likelihood of cardiac myocyte necrosis via a mechanism associated with reduced mitochondrial damage.

Heart rate dynamics in doxorubicin-induced cardiomyopathy

The clinical use of doxorubicin, an effective chemotherapeutic is hampered by the development of irreversible cardiotoxicity. Here we test time-frequency analysis of heart rate (HR) variability (HRV) for early detection of doxorubicin-induced cardiotoxicity. Experiments were conducted in adult male Wistar rats treated for 15 days with doxorubicin (DOXO, total dose 15 mg kg(-1), i.p.) or saline (CONT). DOXO rats exhibited cardiotoxicity confirmed by histological examination without developing heart failure as estimated by echocardiography. However, HR variability increase reflected subtle microscopic changes of cardiac toxicity in DOXO rats. The results recommend time-frequency analysis of HRV for early detection of doxorubicin-induced cardiomyopathy.

Captopril partially decreases the effect of H(2)S on rat blood pressure and inhibits H(2)S-induced nitric oxide release from S-nitrosoglutathione

We studied the effects of the H(2)S donor Na(2)S on the mean arterial blood pressure (MAP) and heart and breathing rates of anesthetized Wistar rats in the presence and absence of captopril. Bolus administration of Na(2)S (1-4 micromol/kg) into the right jugular vein transiently decreased heart and increased breathing rates; at 8-30 micromol/kg, Na(2)S had a biphasic effect, transiently decreasing and increasing MAP, while transiently decreasing heart rate and increasing and decreasing breathing rate. These results may indicate independent mechanisms by which H(2)S influences MAP and heart and breathing rates. The effect of Na(2)S in decreasing MAP was less pronounced in the presence of captopril (2 micromol/l), which may indicate that the renin-angiotensin system is partially involved in the Na(2)S effect. Captopril decreased H(2)S-induced NO release from S-nitrosoglutathione, which may be related to some biological activities of H(2)S. These results contribute to the understanding of the effects of H(2)S on the cardiovascular system.