Potential roles of 4HNE-adducted protein in serum extracellular vesicles as an early indicator of oxidative response against doxorubicin-induced cardiomyopathy in rats

Late-onset cardiomyopathy is becoming more common among cancer survivors, particularly those who received doxorubicin (DOXO) treatment. However, few clinically available cardiac biomarkers can predict an unfavorable cardiac outcome before cell death. Extracellular vesicles (EVs) are emerging as biomarkers for cardiovascular diseases and others. This study aimed to measure dynamic 4-hydroxynonenal (4HNE)-adducted protein levels in rats treated chronically with DOXO and examine their link with oxidative stress, antioxidant gene expression in cardiac tissues, and cardiac function. Twenty-two male Wistar rats were randomly assigned to receive intraperitoneal injection of normal saline (n = 8) or DOXO (3 mg/kg, 6 doses, n = 14). Before and after therapy, serum EVs and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were determined. Tunable resistive pulse sensing was used to measure EV size and concentration. ELISA was used to assess 4HNE-adducted protein in EVs and cardiac tissues. Differential-display reverse transcription-PCR was used to quantitate cardiac Cat and Gpx1 gene expression. Potential correlations between 4HNE-adducted protein levels in EVs, cardiac oxidative stress, antioxidant gene expression, and cardiac function were determined. DOXO-treated rats showed more serum EV 4HNE-adducted protein than NSS-treated rats at day 9 and later endpoints, whereas NT-proBNP levels were not different between groups. Moreover, on day 9, surviving rats' EVs had higher levels of 4HNE-adducted protein, and these correlated positively with concentrations of heart tissue 4HNE adduction and copy numbers of Cat and Gpx1, while at endpoint correlated negatively with cardiac functions. Therefore, 4HNE-adducted protein in serum EVs could be an early, minimally invasive biomarker of the oxidative response and cardiac function in DOXO-induced cardiomyopathy.

Vagus nerve stimulation and acetylcholinesterase inhibitor donepezil provide cardioprotection against trastuzumab-induced cardiotoxicity in rats by attenuating mitochondrial dysfunction

Trastuzumab (Trz) is a targeted anticancer drug for human epidermal growth factor receptor 2 (HER2)-positive tumors, as Trz-induced cardiotoxicity (TIC) is commonly observed in Trz-treated patients. Since cardiac autonomic modulation with electrical vagus nerve stimulation (VNS) and acetylcholinesterase (AChE) inhibitors exerts cardioprotection against various heart diseases, the comparative effects of electrical VNS and an AChE inhibitor (donepezil) on cardiac and mitochondrial functions and programmed cell death pathways in TIC are not known. VNS devices were implanted in thirty-two male Wistar rats and were divided into 4 groups: (i) Control-Sham (CSham), (ii) Trz-Sham (TSham), (iii) Trz-VNS (TVNS), and (iv) Trz-donepezil (TDPZ). Rats in the Trz-treated groups were intraperitoneally injected with Trz (4 mg/kg/day) for 7 days, while CSham rats were injected with NSS. VNS devices were activated in the TVNS rats during the 7-day Trz treatment, but not in the sham rats. Rats in the TDPZ group received donepezil orally (5 mg/kg/day) for 7 days. At the end, left ventricular (LV) function and heart rate variability were evaluated, and heart tissue was collected for biochemical and histological analysis. Trz rats showed LV dysfunction and cardiac sympathovagal imbalance. In addition, mitochondrial function and dynamics were impaired in TIC rats. Trz also increased cardiomyocyte death by inducing apoptosis, pyroptosis, and ferroptosis. Electrical VNS and donepezil had similar efficacy in alleviating cardiac mitochondrial dysfunction, dynamic imbalances, and cardiomyocyte death, leading to improved LV function. These findings suggested that parasympathetic activation via either VNS or an AChE inhibitor could be a promising therapeutic intervention against TIC.

Acetylcholine receptor agonists effectively attenuated multiple program cell death pathways and improved left ventricular function in trastuzumab-induced cardiotoxicity in rats

AIMS

Cardiotoxicity is a seriously debilitating complication of trastuzumab (TRZ) therapy in patients with cancer as a consequence of overexpression of the human epidermal growth factor receptor 2. Although most TRZ-induced cardiotoxicity (TIC) cases are reversible, some patients experience chronic cardiac dysfunction, and these irreversible concepts may be associated with cardiomyocyte death. Acetylcholine receptor (AChR) activation has been shown to exert cardioprotection in several heart diseases, but the effects of AChR agonists against TIC have not been investigated.

MAIN METHOD

Forty adult male Wistar rats were randomized into 5 groups: (i) CON (0.9 % normal saline), (ii) TRZ (4 mg/kg/day), (iii) TRZ + α7nAChR agonist (PNU-282987: 3 mg/kg/day), (iv) TRZ + mAChR agonists (bethanechol: 12 mg/kg/day), and (v) TRZ + combined treatment (Combined PNU-282987 and bethanechol).

KEY FINDINGS

The progression of TIC was driven by mitochondrial dysfunction, autophagic deficiency, and excessive myocyte death including by pyroptosis, ferroptosis, and apoptosis, which were significantly alleviated by α7nAChR and mAChR agonists. Interestingly, necroptosis was not associated with development of TIC. More importantly, the in vitro study validated the cytoprotective effects of AChR activation in TRZ-treated H9c2 cells, while not interfering with the anticancer properties of TRZ. All of these findings indicated that TRZ induced mitochondrial dysfunction, autophagic deficiency, and excessive myocyte death including pyroptosis, ferroptosis, and apoptosis, leading to impaired cardiac function. These pathological alterations were attenuated by α7nAChR and mAChR agonists.

SIGNIFICANCE

α7nAChR and mAChR agonists might be used as a future therapeutic target in the mitigation of TIC.

Acetylcholinesterase inhibition protects against trastuzumab-induced cardiotoxicity through reducing multiple programmed cell death pathways

BACKGROUND

Trastuzumab (Trz)-induced cardiotoxicity (TIC) is one of the most common adverse effects of targeted anticancer agents. Although oxidative stress, inflammation, mitochondrial dysfunction, apoptosis, and ferroptosis have been identified as potential mechanisms underlying TIC, the roles of pyroptosis and necroptosis under TIC have never been investigated. It has been shown that inhibition of acetylcholinesterase function by using donepezil exerts protective effects in various heart diseases. However, it remains unknown whether donepezil exerts anti-cardiotoxic effects in rats with TIC. We hypothesized that donepezil reduces mitochondrial dysfunction, inflammation, oxidative stress, and cardiomyocyte death, leading to improved left ventricular (LV) function in rats with TIC.

METHODS

Male Wistar rats were randomly assigned to be Control or Trz groups (Trz 4 mg/kg/day, 7 days, I.P.). Rats in Trz groups were assigned to be co-treated with either drinking water (Trz group) or donepezil 5 mg/kg/day (Trz + DPZ group) via oral gavage for 7 days. Cardiac function, heart rate variability (HRV), and biochemical parameters were evaluated.

RESULTS

Trz-treated rats had impaired LV function, HRV, mitochondrial function, and increased inflammation and oxidative stress, leading to apoptosis, ferroptosis, and pyroptosis. Donepezil co-treatment effectively decreased those adverse effects of TIC, resulting in improved LV function. An in vitro study revealed that the cytoprotective effects of donepezil were abolished by a muscarinic acetylcholine receptor (mAChR) antagonist.

CONCLUSIONS

Donepezil exerted cardioprotection against TIC via attenuating mitochondrial dysfunction, oxidative stress, inflammation, and cardiomyocyte death, leading to improved LV function through mAChR activation. This suggests that donepezil could be a novel intervention strategy in TIC.

Melatonin and metformin ameliorated trastuzumab-induced cardiotoxicity through the modulation of mitochondrial function and dynamics without reducing its anticancer efficacy

Trastuzumab has an impressive level of efficacy as regards antineoplasticity, however it can cause serious cardiotoxic side effects manifested by impaired cardiac contractile function. Although several pharmacological interventions, including melatonin and metformin, have been reported to protect against various cardiovascular diseases, their potential roles in trastuzumab-induced cardiotoxicity remain elusive. We hypothesized that either melatonin or metformin co-treatment effectively attenuates trastuzumab-mediated cardiotoxicity through attenuating the impaired mitochondrial function and mitochondrial dynamics. Male Wistar rats were divided into control (normal saline, n = 8) and trastuzumab group (4 mg/kg/day for 7 days, n = 24). Rats in the trastuzumab group were subdivided into 3 interventional groups (n = 8/group), and normal saline, or melatonin (10 mg/kg/day), or metformin (250 mg/kg/day) were orally administered for 7 consecutive days. Cardiac parameters were determined, and biochemical investigations were carried out on blood and heart tissues. Trastuzumab induced left ventricular (LV) dysfunction by increasing oxidative stress, inflammation, and apoptosis. It also impaired cardiac mitochondrial function, dynamics, and autophagy. Treatment with either melatonin or metformin equally attenuated trastuzumab-induced cardiac injury, indicated by a marked reduction in inflammation, oxidative damage, cardiac mitochondrial injury, mitochondrial dynamic imbalance, autophagy dysregulation, and apoptosis, leading to improved LV function, as demonstrated by increased LV ejection fraction. Melatonin and metformin conferred equal levels of cardioprotection against trastuzumab-induced cardiotoxicity, which may provide novel and promising approaches for management of cardiotoxicity induced by trastuzumab.

Melatonin and metformin counteract cognitive dysfunction equally in male rats with doxorubicin-induced chemobrain

Melatonin (Mel) and metformin (Met) show beneficial effects in various brain pathologies. However, the effects of Mel and Met on doxorubicin (DOX)-induced chemobrain remain in need of elucidation. We aimed to investigate whether Mel and Met provide neuroprotective effects on glial dysmorphologies, brain inflammation, oxidative stress, brain mitochondrial dysfunction, apoptosis, necroptosis, neurogenesis, hippocampal dysplasticity, and cognitive dysfunction in rats with DOX-induced chemobrain. Thirty-two male Wistar rats were divided into 2 groups and received normal saline (NSS, as control, n = 8) or DOX (3 mg/kg/day; n = 24) by intraperitoneal (i.p.) injection on days 0, 4, 8, 15, 22, and 29. The DOX-treated group was divided into 3 subgroups receiving either vehicle (NSS; n = 8), Mel (10 mg/kg/day; n = 8), or Met (250 mg/kg/day; n = 8) by gavage for 30 consecutive days. Following this, cognitive function was assessed in all rats. The number of glial cells and their fluorescence intensity had decreased, while the glial morphology in DOX-treated rats showed a lower process complexity. Brain mitochondrial dysfunction, an increase in brain inflammation, oxidative stress, apoptosis and necroptosis, a decrease in the number of hippocampal dendritic spines and neurogenesis, and cognitive decline were also observed in DOX-treated rats. Mel and Met equally improved those brain pathologies, resulting in cognitive improvement in DOX-treated rats. In conclusion, concomitant treatment with either Mel or Met counteract DOX-induced chemobrain by preservation of glial morphology, brain inflammation, brain oxidative stress, brain mitochondrial function, hippocampal plasticity, and brain apoptosis. This study highlighted the role of the glia as key mediators in DOX-induced chemobrain.

Vagus nerve stimulation exerts cardioprotection against doxorubicin-induced cardiotoxicity through inhibition of programmed cell death pathways

The aberration of programmed cell death including cell death associated with autophagy/mitophagy, apoptosis, necroptosis, pyroptosis, and ferroptosis can be observed in the development and progression of doxorubicin-induced cardiotoxicity (DIC). Vagus nerve stimulation (VNS) has been shown to exert cardioprotection against cardiomyocyte death through the release of the neurotransmitter acetylcholine (ACh) under a variety of pathological conditions. However, the roles of VNS and its underlying mechanisms against DIC have never been investigated. Forty adults male Wistar rats were divided into 5 experimental groups: (i) control without VNS (CSham) group, (ii) doxorubicin (3 mg/kg/day, i.p.) without VNS (DSham) group, (iii) doxorubicin + VNS (DVNS) group, (iv) doxorubicin + VNS + mAChR antagonist (atropine; 1 mg/kg/day, ip, DVNS + Atro) group, and (v) doxorubicin + VNS + nAChR antagonist (mecamylamine; 7.5 mg/kg/day, ip, DVNS + Mec) group. Our results showed that doxorubicin insult led to left ventricular (LV) dysfunction through impaired cardiac autonomic balance, decreased mitochondrial function, imbalanced mitochondrial dynamics, and exacerbated cardiomyocyte death including autophagy/mitophagy, apoptosis, necroptosis, pyroptosis, and ferroptosis. However, VNS treatment improved cardiac mitochondrial and autonomic functions, and suppressed excessive autophagy, apoptosis, necroptosis, pyroptosis, and ferroptosis, leading to improved LV function. Consistent with this, ACh effectively improved cell viability and suppressed cell cytotoxicity in doxorubicin-treated H9c2 cells. In contrast, either inhibitors of muscarinic (mAChR) or nicotinic acetylcholine receptor (nAChR) completely abrogated the favorable effects mediated by VNS and acetylcholine. These findings suggest that VNS exerts cardioprotective effects against doxorubicin-induced cardiomyocyte death via activation of both mAChR and nAChR.

Cardiac autonomic modulation with donepezil attenuates pyroptosis and mitochondrial dysfunction, leading to improved left ventricular function in trastuzumab-induced cardiotoxicity in rats

Background

Trastuzumab (Trz)-induced cardiotoxicity (TIC) is one of the most common cardiovascular complications of targeted anticancer agents. Cardiac inflammation, cardiac mitochondrial dysfunction, oxidative stress, and cardiac autonomic dysfunction have been identified as potential mechanisms underlying the adverse effects of TIC. Although cardiac inflammation is one of the key mechanisms triggering “pyroptosis”, i.e. a new inflammatory form of programmed cell death, the association between TIC and pyroptosis is still largely unknown. Moreover, the modulation of cardiac autonomic activity using an acetylcholinesterase inhibitor (AChE) has been shown to exert cardioprotection in various heart diseases. However, the role of donepezil (DPZ), an AChE, in treating TIC has never been investigated.

Purpose

We evaluated the cardioprotective effects of DPZ on left ventricular (LV) function, cardiac mitochondrial function, and pyroptosis in rats with TIC. We hypothesised that DPZ reduces mitochondrial dysfunction and pyroptosis, leading to a reduction of LV dysfunction in TIC rats.

Methods

Fifteen male Wistar rats were randomly divided into the control group (n=5, 0.9% normal saline solution, ip) and the Trz group (n=10, 4 mg/kg/day for 7 days, ip). Trz-treated rats were subdivided into the vehicle group (n=5, drinking water, po) and the DPZ group (n=5, 5 mg/kg/day for 7 days, po). At the end of the experiment, echocardiography was performed, and the heart was removed to determine the cardiac mitochondrial function and pyroptosis.

Results

Compared with the control group, %LV ejection fraction (%LVEF) was significantly decreased in the Trz group (Fig. 1A). Trz treatment also markedly increased cardiac mitochondrial reactive oxygen species (ROS) production and mitochondrial depolarisation, as indicated by a lower red/green fluorescence intensity ratio (Fig. 1B and C, respectively). Furthermore, Trz induced pyroptosis by increasing NLR family pyrin domain containing 3 (NLRP3) expression and cleaved Gasdermin D/Gasdermin D ratio, compared to the control group (Fig, 1D–F). Notably, DPZ co-treatment potentially reduced mitochondrial ROS production, mitochondrial depolarisation, and pyroptosis (NLRP3 and cleaved Gasdermin D/Gasdermin D ratio), leading to improved %LVEF (Figure 1).

Conclusion

DPZ alleviated cardiac dysfunction in TIC rats by improving mitochondrial function and reducing pyroptosis. These findings suggested that DZP could be a novel effective pharmacological intervention against TIC.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): 1. The National Science and Technology Development Agency Thailand2. The Thailand Research Fund (RGJ)

Ranolazine alleviated cardiac/brain dysfunction in doxorubicin-treated rats

Doxorubicin (Dox), a powerful chemotherapeutic agent, has been shown to cause cardiotoxicity and neurotoxicity. Ranolazine, a drug that is commonly used to treat patients with chronic angina, has been shown to reduce toxicity from Dox therapy. Therefore, the present study aims to investigate the mechanisms behind the protective effects of ranolazine on the heart and brain in Dox-treatment. Twenty-four male Wistar rats received 6 doses of either 0.9% normal saline (0.9% NSS, i.p., n = 8) or Dox (3 mg/kg, i.p., n = 16). All Dox-treated rats were assigned into 2 groups to receive vehicle (0.9% NSS, orally; n = 8) or ranolazine (305 mg/kg/day, orally; n = 8) for 30 consecutive days. Following the treatments, left ventricular (LV) function and cognition were determined. Animals were euthanized, then the heart and brain were collected for further analysis. Dox induced systemic oxidative stress/inflammation, and cardiac injury evidenced by mitochondrial dysfunction, mitochondrial dynamic imbalance, and apoptosis, resulting in LV dysfunction. Ranolazine significantly improved LV function via attenuating cardiac injury. Dox also caused brain pathologies as indicated by increased brain inflammation, impaired blood-brain barrier integrity, brain mitochondrial dysfunction, microglial dysmorphology, hippocampal dysplasticity, and increased apoptosis, resulting in cognitive decline. Ranolazine exerted neuroprotective effects by suppressing brain pathologies and restoring cognitive function. These findings suggest that ranolazine has a potential role in cardio- and neuro-protection against chemotherapy.

Acetylcholine receptor agonists provide cardioprotection in doxorubicin-induced cardiotoxicity via modulating muscarinic M2 and α7 nicotinic receptor expression

The balance between cardiac sympathetic and parasympathetic activities has been intricately linked to mitochondrial function, cellular oxidative status, and immunomodulation in healthy and diseased myocardium. Cardiac autonomic neuropathy, along with the associated mitochondrial and cellular dysfunction, is an important pathophysiological feature of doxorubicin-induced cardiotoxicity (DIC). We tested the hypothesis that autonomic modulation by activation of acetylcholine receptors (AChR) effectively attenuates DIC. Rats were divided into control (0.9% sodium chloride solution) and doxorubicin groups (DOX, 3 mg/kg/d, 6 doses). Rats in the DOX group were equally subdivided into 4 interventional groups and treated for 30 days: vehicle, α7 nicotinic receptor agonist (PNU: PNU-282987, 3 mg/kg/d), muscarinic receptor agonist (BET: bethanechol, 12 mg/kg/d), and combined α7nAChR and mAChR agonists group (COM). Cardiac biochemical and functional analyses were done. The results show that AChR agonists protected the heart against DIC via improving mitochondrial and cardiac function, which was accompanied by reducing mitochondrial oxidative damage, apoptosis, and inflammation. Strikingly, PNU and BET exerted cardioprotection through different molecular pathways. PNU-mediated α7nAChR activation promoted mitochondrial fusion via upregulation of Mfn1-2 and attenuated DOX-induced autophagy. Contrarily, activation of mAChR by BET attenuated mitochondrial fission and mitophagy. The in vitro experiments confirmed the cytoprotective effects of AChR activation in DOX-treated H9c2 cells without compromising the anticancer effect of DOX in cancer cells. In conclusion, α7nAChR and mAChR agonists exerted cardioprotection against DIC via rebalancing autonomic function, improving mitochondrial function, reducing oxidative stress, and decreased cardiomyocyte apoptosis and inflammation, leading to improved cardiac function.

Acetylcholinesterase inhibitor ameliorates doxorubicin-induced cardiotoxicity through reducing RIP1-mediated necroptosis

Doxorubicin is an effective chemotherapeutic drug, but causes cardiotoxicity which limits its use. Oxidative stress, mitochondrial dysfunction, and inflammation are closely implicated in doxorubicin-induced cardiotoxicity (DIC). Necroptosis, a new form of programmed cell death, was also upregulated by doxorubicin, leading to cardiomyocyte death and cardiac dysfunction. Donepezil, an acetylcholinesterase inhibitor, exerted cardioprotection against various heart diseases. However, its cardioprotective effects in DIC are still unknown. We hypothesized that donepezil reduces reactive oxygen species (ROS) production, mitochondrial dysfunction, mitochondrial dynamics imbalance, necroptosis, and apoptosis in DIC rats. Male Wistar rats were assigned to receive either normal saline solution (n = 8) or doxorubicin (3 mg/kg, 6 doses, n = 16) via intraperitoneal injection. The doxorubicin-treated rats were further subdivided to receive either sterile drinking water (n = 8) or donepezil (5 mg/kg/day, p.o., n = 8) for 30 days. At the end of the experiment, the left ventricular (LV) function was determined. Serum and heart tissue were collected to evaluate histological and biochemical parameters. Doxorubicin-treated rats exhibited higher levels of inflammatory cytokines and ROS production. Doxorubicin also impaired mitochondrial function, mitochondrial dynamics balance, mitophagy, and autophagy, which culminated in apoptosis. Furthermore, doxorubicin increased necroptosis as evidenced by increased phosphorylation of receptor-interacting protein kinase 1, receptor-interacting protein kinase 3, and mixed-lineage kinase domain-like. All of these mechanisms led to LV dysfunction. Interestingly, donepezil alleviated mitochondrial injury, mitophagy, autophagy, and cardiomyocyte death, leading to improved LV function in DIC. In conclusion, donepezil attenuated DIC-induced LV dysfunction by reducing mitochondrial damage, mitophagy, autophagy, apoptosis, and necroptosis.

Ranolazine exerted cardioprotection against doxorubicin-induced cardiotoxicity through inhibiting excessive autophagy in rats

Background

Doxorubicin (Dox) is a highly effective chemotherapeutic agent for several malignancies. However, its cardiotoxicity and progressive heart failure are the most serious adverse effects that compromised its clinical use. Recently, ranolazine, the late sodium (Na+) current inhibitor for patients with chronic angina, has been suggested as a potential agent to treat early cardiotoxicity induced by antitumor drugs. In that single report, pretreatment with ranolazine improved cardiac function and decreased mortality rates in the Dox-treated rats, by decreasing oxidative stress and apoptosis. Nevertheless, its protective mechanisms on autophagy in the Dox-treated rats have never been elucidated.

Purpose

We hypothesized that ranolazine exerts cardioprotection in the Dox-treated rats by improving left ventricular (LV) function and reducing cardiac injury though suppressing excessive autophagy.

Methods

Male Wistar rats (n=24) received either normal saline solution (NSS, n=8) or Dox (3 mg/kg/day, i.p.) for 6 doses. Then, the Dox-treated rats were assigned to orally administered with either saline (n=8) or ranolazine (305 mg/kg/day, n=8) for 30 consecutive days. Following the treatment, the LV function, cardiac injury, and autophagy were determined.

Results

Dox caused LV dysfunction as indicated by the decreased %LV ejection fraction (LVEF) and the increased serum cardiac troponin-I (cTn-I) levels (Fig. 1A). In addition, Dox induced excessive autophagy by increasing Beclin-1, p62, and light chain 3-II/I (LC3II/I) protein expressions (Fig. 1B). Treatment with ranolazine attenuated autophagic-related proteins (Beclin-1, p62, and LC3II/I), and improved LV function (Fig. 1A-B).

Conclusion

Ranolazine exerted cardioprotection in the Dox-treated rats through suppressing autophagic-regulatory proteins, suggesting its potential cardioprotective roles as a concomitant therapy for cancer patients receiving Dox.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): the NSTDA Research Chair grant from the National Science and Technology Development Agency Thailand and the National Research Council of Thailand

Cardioprotective effects of melatonin and metformin against doxorubicin-induced cardiotoxicity in rats are through preserving mitochondrial function and dynamics

Doxorubicin (Dox) is widely used in chemotherapy regimens for several malignant conditions. Unfortunately, cumulative and irreversible cardiotoxicity of Dox is the most prominent adverse effect which limits its use. Several pharmacological interventions which exert antioxidant properties, including melatonin and metformin, have demonstrated beneficial effects against various cardiac pathological conditions. However, the exact molecular mechanisms underlying their cardioprotective effects are not completely understood. We hypothesized that treatment with either melatonin or metformin provides cardioprotection against Dox-induced cardiotoxicity through mitochondrial protection. Thirty-two male Wistar rats received 6 doses of either 0.9% normal saline solution (0.9% NSS, n = 8) or Dox (3 mg/kg, i.p., n = 24). The Dox-treated rats (n = 8/group) were co-treated with: 1) Vehicle (0.9% NSS), 2) Melatonin (10 mg/kg/day), and 3) Metformin (250 mg/kg/day) for 30 consecutive days via oral gavage. Following the treatment, left ventricular (LV) function, oxidative stress, inflammation, mitochondrial function, dynamics, biogenesis and bioenergetics, mitophagy, autophagy, and apoptosis were determined. Dox induced excessive oxidative stress, inflammation, autophagy, apoptosis, reduced mitochondrial function, dynamics balance, biogenesis, and bioenergetics leading to LV dysfunction. Treatment with either melatonin or metformin exerted equal measures of cardioprotection via reducing oxidative stress, inflammation, autophagy, apoptosis, and improved mitochondrial function, dynamics balance, biogenesis, and bioenergetics in the Dox-treated rats. Melatonin and metformin exerted both anti-cancer and cardioprotective properties, suggesting they have potential roles in concomitant therapy in cancer patients receiving Dox treatment.