Doxorubicin and cyclophosphamide lead to long-lasting impairment of spatial memory in female, but not male mice

Letrozole delays acquisition of water maze task in female BALB/c mice: Possible involvement of anxiety

Letrozole, an aromatase inhibitor preventing estrogen synthesis from testosterone, is used as an adjuvant therapy in estrogen receptor-positive breast cancer patients. However, like other aromatase inhibitors, it induces many side effects, including impaired cognition. Despite its negative effect in humans, results from animal models are inconsistent and suggest that letrozole can either impair or improve cognition. Here, we studied the effects of chronic letrozole treatment on cognitive behavior of adult female BALB/c mice, a relevant animal model for breast cancer studies, to develop an appropriate animal model aimed at testing therapies to mitigate side effects of letrozole. In Morris water maze, letrozole 0.1 mg/kg impaired reference learning and memory. Interestingly, most of the letrozole 0.1 mg/kg-treated mice were able to learn the new platform position in reversal training and performed similar to control mice in a reversal probe test. Results of the reversal test suggest that letrozole did not completely disrupt spatial navigation, but rather delayed acquisition of spatial information. The delay might be related to increased anxiety as suggested by increased thigmotactic behavior during the reference memory training. The learning impairment was water maze-specific since we did not observe impairment in other spatial tasks such as in Y-maze or object location test. In contrast, the dose of 0.3 mg/kg did not have effect on water maze learning and facilitated locomotor habituation and recognition in novel object recognition test. The current study shows that letrozole dose-dependently modulates behavioral response and that its effects are task-dependent.

More than a small adult brain: Lessons from chemotherapy-induced cognitive impairment for modelling paediatric brain disorders

Childhood is recognised as a period of immense physical and emotional development, and this, in part, is driven by underlying neurophysiological transformations. These neurodevelopmental processes are unique to the paediatric brain and are facilitated by augmented rates of neuroplasticity and expanded neural stem cell populations within neurogenic niches. However, given the immaturity of the developing central nervous system, innate protective mechanisms such as neuroimmune and antioxidant responses are functionally naïve which results in periods of heightened sensitivity to neurotoxic insult. This is highly relevant in the context of paediatric cancer, and in particular, the neurocognitive symptoms associated with treatment, such as surgery, radio- and chemotherapy. The vulnerability of the developing brain may increase susceptibility to damage and persistent symptomology, aligning with reports of more severe neurocognitive dysfunction in children compared to adults. It is therefore surprising, given this intensified neurocognitive burden, that most of the pre-clinical, mechanistic research focuses exclusively on adult populations and extrapolates findings to paediatric cohorts. Given this dearth of age-specific research, throughout this review we will draw comparisons with neurodevelopmental disorders which share comparable pathways to cancer treatment related side-effects. Furthermore, we will examine the unique nuances of the paediatric brain along with the somatic systems which influence neurological function. In doing so, we will highlight the importance of developing in vitro and in vivo paediatric disease models to produce age-specific discovery and clinically translatable research.

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.

Anthracycline chemotherapy, vascular dysfunction and cognitive impairment: burgeoning topics and future directions

Anthracyclines, chemotherapeutic agents used to treat common forms of cancer, increase cardiovascular (CV) complications, thereby necessitating research regarding interventions to improve the health of cancer survivors. Vascular dysfunction, which is induced by anthracycline chemotherapy, is an established antecedent to overt CV diseases. Potential treatment options for ameliorating vascular dysfunction have largely been understudied. Furthermore, patients treated with anthracyclines have impaired cognitive function and vascular dysfunction is an independent risk factor for the development of mild cognitive impairment. Here, we will focus on: anthracycline chemotherapy associated CV diseases risk; how targeting mechanisms underlying vascular dysfunction may be a means to improve both CV and cognitive health; and research gaps and potential future directions for the field of cardio-oncology.

Quetiapine Moderates Doxorubicin-Induced Cognitive Deficits: Influence of Oxidative Stress, Neuroinflammation, and Cellular Apoptosis

Chemotherapy is considered a major choice in cancer treatment. Unfortunately, several cognitive deficiencies and psychiatric complications have been reported in patients with cancer during treatment and for the rest of their lives. Doxorubicin (DOX) plays an important role in chemotherapy regimens but affects both the central and peripheral nervous systems. Antipsychotic drugs alleviate the behavioral symptoms of aging-related dementia, and the atypical class, quetiapine (QUET), has been shown to have beneficial effects on various cognitive impairments. The present investigation aimed to determine the possible mechanism underlying the effect of thirty-day administrations of QUET (10 or 20 mg/kg, p.o.) on DOX-induced cognitive deficits (DICDs). DICDs were achieved through four doses of DOX (2 mg/kg, i.p.) at an interval of seven days during drug treatment. Elevated plus maze (EPM), novel object recognition (NOR), and Y-maze tasks were performed to confirm the DICDs and find the impact of QUET on them. The ELISA tests were executed with oxidative [malondialdehyde (MDA), catalase, and reduced glutathione (GSH)], inflammatory [cyclooxygenase-2 (COX-2), nuclear factor kappa B (NF-κB), and tumor necrosis factor-alpha (TNF-α)], and apoptosis [B-cell lymphoma 2 (Bcl2), Bcl2 associated X protein (Bax), and Caspase-3] markers were assessed in the brain homogenate to explore the related mechanisms. DICD lengthened the transfer latency time in EPM, shortened the exploration time of the novel object, reduced the discrimination ability of the objects in NOR, and lowered the number of arm entries and time spent in the novel arm. QUET alleviated DICD-related symptoms. In addition, QUET reduced neuronal oxidative stress by reducing MDA and elevating GSH levels in the rat brain. Moreover, it reduced neuronal inflammation by controlling the levels of COX-2, NF-κB, and TNF-α. By improving the Bcl-2 level and reducing both Bax and Caspase-3 levels, it protected against neuronal apoptosis. Collectively, our results supported that QUET may protect against DICD, which could be explained by the inhibition of neuronal inflammation and the attenuation of cellular apoptosis protecting against oxidative stress.

Hippocampal neuroinflammation following combined exposure to cyclophosphamide and naproxen in ovariectomized mice

Aim: Cancer patients undergoing chemotherapy report cognitive changes collectively termed "chemo brain." Neuroinflammation is among the factors believed to contribute to "chemo brain" suggesting a potential beneficial role for anti-inflammatory drugs in cancer patients undergoing chemotherapy. We investigated whether the non-steroidal anti-inflammatory drug naproxen influenced hippocampal inflammation in non-tumor bearing female mice receiving the chemotherapy drug cyclophosphamide (CP).Materials and methods: Intact and ovariectomized C57BL/6 mice were used to examine potential role of ovarian hormones on neuroinflammation. The mice were placed on naproxen (375 ppm) or control diet, and a week later CP (100 mg/kg; i.p.) was administered every 3 days for 2 weeks. We analyzed hippocampal inflammatory biomarkers, anxiety-like behavior, spatial working memory, exploratory behavior, spontaneous locomotor activity and depression-like behavior.Results: CP produced significant effects on anti-inflammatory but not pro-inflammatory biomarkers. However, CP and naproxen in combination produced significant effects on both pro- and anti- inflammatory biomarkers. Naproxen and ovariectomy individually produced significant effects on pro- and anti-inflammatory biomarkers as well. Working memory and depression-like behavior were not significantly influenced by CP, naproxen or ovariectomy individually although CP and ovariectomy produced significant interaction effects on depression-like behavior. Exploratory behavior and locomotor activity showed significant effects of CP, and interaction between CP and naproxen was significant for locomotor activity.Conclusions: Ovariectomy, naproxen and a combination of CP and naproxen upregulate hippocampal pro- and anti- inflammatory biomarkers. None of the factors individually produce significant behavioral changes that could be consistent with chemo brain, although CP and ovariectomy in combination produced significant effects on depression-like behavior, a co-morbidity of chemo brain.

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.

Immunomodulatory effect of protocatechuic acid on cyclophosphamide induced brain injury in rat: Modulation of inflammosomes NLRP3 and SIRT1

Modulation of the inflammasome NLRP3 and SIRT1 are new combat strategy for brain injury protection. The inflammasome activates proinflammatory cytokines releasing interleukin-1β and interleukin-18 which in turn affect the toxins release from immune cells. In addition, SIRT1 controls many biological functions, such as immune response and oxidative stress. Protocatechuic has versatile biological activities and possesses antioxidant, anti-inflammatory and neuroprotective effects. So this work aims to study immunomodulatory effect of protocatechuic acid on cyclophosphamide chemotherapy drug-induced brain injury via modulation of inflammosomes NLRP3 and SIRT1. Rats were randomly assigned to four experimental groups. Normal control group was injected with a single i.p injection of saline. Cyclophosphamide group was injected with a single i.p injection of cyclophosphamide (200 mg/kg). Protocatechuic acid groups were orally administered (50 &100 mg/kg) once daily for 10 consecutive days after cyclophosphamide injection. Protocatechuic acid administration exhibited improvements of the cognition function and memory, a reduction in brain contents of MDA, NLRP3, IL-1 β, NF-κB, IKBKB and Galectin 3 and an elevation of GSH and SIRT1 compared to cyclophosphamide group. In addition, protocatechuic acid administration ameliorated the elevation of caspase 3 and iNOS gene expression and alleviated the neuron degeneration caused by cyclophosphamide. In conclusion, the therapeutic action of protocatechuic acid and its cellular and molecular mechanisms are new insights against various human ailments, especially, neuroprotective disease as brain injury induced by cyclophosphamide chemotherapy drug in rats through modulation of inflammosomes NLRP3 and SIRT1.

Chemobrain in Breast Cancer: Mechanisms, Clinical Manifestations, and Potential Interventions

Among the potential adverse effects of breast cancer treatment, chemotherapy-related cognitive impairment (CRCI) has gained increased attention in the past years. In this review, we provide an overview of the literature regarding CRCI in breast cancer, focusing on three main aspects. The first aspect relates to the molecular mechanisms linking individual drugs commonly used to treat breast cancer and CRCI, which include oxidative stress and inflammation, reduced neurogenesis, reduced levels of specific neurotransmitters, alterations in neuronal dendrites and spines, and impairment in myelin production. The second aspect is related to the clinical characteristics of CRCI in patients with breast cancer treated with different drug combinations. Data suggest the incidence rates of CRCI in breast cancer vary considerably, and may affect more than 50% of treated patients. Both chemotherapy regimens with or without anthracyclines have been associated with CRCI manifestations. While cross-sectional studies suggest the presence of symptoms up to 20 years after treatment, longitudinal studies confirm cognitive impairments lasting for at most 4 years after the end of chemotherapy. The third and final aspect is related to possible therapeutic interventions. Although there is still no standard of care to treat CRCI, several pharmacological and non-pharmacological approaches have shown interesting results. In summary, even if cognitive impairments derived from chemotherapy resolve with time, awareness of CRCI is crucial to provide patients with a better understanding of the syndrome and to offer them the best care directed at improving quality of life.

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.

Motopsin deficiency imparts partial insensitivity to doxorubicin-induced hippocampal impairments in adult mice

Motopsin is a serine protease that plays a crucial role in synaptic functions. Loss of motopsin function causes severe intellectual disability in humans. In this study, we evaluated the role of motopsin in the neuropathological development of cognitive impairments following chemotherapy, also known as chemobrain. Motopsin knockout (KO) and wild-type (WT) mice were intravenously injected with doxorubicin (Dox) or saline four times every 8 days and were evaluated for open field, novel object recognition, and passive avoidance tests. Parvalbumin-positive neurons in the hippocampus were immunohistochemically analyzed. Dox administration significantly decreased the total distance in the open field test in both WT and motopsin KO mice without affecting the duration spent in the center square. A significant interaction between the genotype and drug treatment was detected in the recognition index (the rate to investigate a novel object) in the novel object recognition test, although Dox treatment did not affect the total investigation time. Additionally, Dox treatment significantly decreased the recognition index in WT mice, whereas it tended to increase the recognition index in motopsin KO mice. Dox treatment did not affect the latency to enter a dark compartment in either WT or motopsin KO mice in the passive avoidance test. Interestingly, Dox treatment increased the parvalbumin-positive neurons in the stratum oriens of the hippocampus CA1 region of only WT mice, not motopsin KO mice. Our data suggest that motopsin deficiency imparted partial insensitivity to Dox-induced hippocampal impairments. Alternatively, motopsin may contribute to the neuropathology of chemobrain.

Increasing dietary choline attenuates spatial memory deficits resulting from exposure to the chemotherapeutic agents cyclophosphamide and doxorubicin

BACKGROUND

Choline supplementation (+Ch) improves cognitive function in impaired animals and humans. Chemotherapy-related cognitive deficits (CRCDs) occur in cancer patients, and these deficits persist following treatment, adversely impacting quality of life. To date, there are no approved treatments for this condition.

AIM

Because +Ch improves impaired memory, it was of interest to determine whether +Ch can attenuate spatial memory deficits induced by the chemotherapeutic agents doxorubicin (DOX) and cyclophosphamide (CYP).

METHODS

Female BALB/C mice, 64 days of age, were trained in the Morris water maze and baseline performance determined on day 15. Following baseline assessment, mice were placed on +Ch diet (2.0% Ch) or remained on standard diet (0.12% Ch). Mice received intravenous injections of DOX (2.5 mg/kg) and CYP (25 mg/kg), or equivalent volumes of saline (0.9% NaCl), on days 16, 23, 30, and 37, and spatial memory was assessed weekly from day 22 to 71.

RESULTS

DOX and CYP produced a prolonged impairment in spatial memory as indicated by an increased latency to the correct zone (p < 0.05), and a decrease in time in the correct zone (p < 0.05), % of total swim distance in the correct zone (p < 0.05) and % entries to the correct zone (p < 0.05). These effects were attenuated by +Ch.

CONCLUSION

Although it remains to be determined whether this effect extends to other cognitive domains and whether +Ch is prophylactic or therapeutic, these findings suggest that +Ch may be an effective intervention for CRCDs.

Accelerated aging of the brain transcriptome by the common chemotherapeutic doxorubicin

Cancer is one of the most common age-related diseases, and over one-third of cancer patients will receive chemotherapy. One frequently reported side effect of chemotherapeutic agents like doxorubicin (Doxo) is impaired cognitive function, commonly known as "chemotherapy-induced cognitive impairment (CICI)", which may mimic accelerated brain aging. The biological mechanisms underlying the adverse effects of Doxo on the brain are unclear but could involve mitochondrial dysfunction. Here, we characterized brain (hippocampal) transcriptome and cognitive/behavioral changes in young mice treated with Doxo +/- the mitochondrial therapeutic MitoQ. We found that Doxo altered transcriptome/biological processes related to synaptic transmission and neurotransmitter function, neuronal health and behavior, and that these gene expression changes were: 1) similar to key differences observed in transcriptome data on brain aging; and 2) associated with related, aging-like behavioral differences, such as decreased exploration time and impaired novel object recognition test (NOR, an index of learning/memory) performance. Interestingly, MitoQ partially prevented Doxo-induced transcriptome changes in the brain, but it had no effect on behavior or cognitive function. Collectively, our findings are consistent with the idea that chemotherapeutic agents could induce neuronal/gene expression and behavioral changes similar to those that occur during brain aging. In this context, mitochondrial therapeutics may have potential as treatments for CICI at the biological level, but their effects on behavior/cognitive function require further investigation.

Curcumin Administration Mitigates Cyclophosphamide-Induced Oxidative Damage and Restores Alteration of Enzymes Associated with Cognitive Function in Rats' Brain

The use of chemotherapeutic drugs is associated with oxidative damage, cognitive dysfunction, and brain damage. This study sought to investigate the neuroprotective effect of curcumin against cognitive problems associated with treatment with cyclophosphamide via assessment of biomolecules associated with cognitive function in rats' brain homogenates. Rats were divided in to five groups: Control (vehicle), CUR (curcumin [20 mg/kg]), CPA (cyclophosphamide [150 mg/kg]), CUR1 + CPA (curcumin [20 mg/kg] and cyclophosphamide [150 mg/kg]), and CPA + CUR2 (cyclophosphamide [150 mg/kg] and curcumin [20 mg/kg]). After the treatment, cognitive behavior was assessed and enzymes [cholinesterases, purinergic enzymes, arginase, and angiotensin I-converting enzyme] associated with cognitive function were examined. Oxidative stress parameters [total thiol, non-protein thiol, malondialdehyde, and nitric oxide] including the expression of caspase-3 were also assessed in rats' brain. Our results showed that curcumin improved cognitive behavior, attenuated cholinergic deficit as revealed by the inhibition of cholinesterases, and improved purinergic signaling in cyclophosphamide-treated rats. Furthermore, curcumin reduced angiotensin-I-converting enzyme and arginase activities before and after treatment with cyclophosphamide. Curcumin also improved redox balance and showed protection against cyclophosphamide-induced oxidative damage to rats' brain via an increase in protein and non-protein thiols and nitric oxide levels as well as a significant reduction in malondialdehyde levels. Curcumin also prevented neuronal degeneration in different brain regions and reduced caspase-3 expression. Hence this study suggests that pre and post-treatment with curcumin improved neurobehavior, modulates some biomarkers associated with cognitive function and exhibit neuroprotection against cyclophosphamide-induced neurotoxicity in rats.

Assessing the Effects of Redox Modifier MnTnBuOE-2-PyP 5+ on Cognition and Hippocampal Physiology Following Doxorubicin, Cyclophosphamide, and Paclitaxel Treatment

Background: Chemotherapy treatment for breast cancer can induce cognitive impairments often involving oxidative stress. The brain, as a whole, is susceptible to oxidative stress due to its high-energy requirements, limited anaerobic respiration capacities, and limited antioxidant defenses. The goal of the current study was to determine if the manganese porphyrin superoxide dismutase mimetic MnTnBuOE-2-PyP (MnBuOE) could ameliorate the effects of doxorubicin, cyclophosphamide, and paclitaxel (AC-T) on mature dendrite morphology and cognitive function. Methods: Four-month-old female C57BL/6 mice received intraperitoneal injections of chemotherapy followed by subcutaneous injections of MnBuOE. Four weeks following chemotherapy treatment, mice were tested for hippocampus-dependent cognitive performance in the Morris water maze. After testing, brains were collected for Golgi staining and molecular analyses. Results: MnBuOE treatment preserved spatial memory during the Morris water-maze. MnBuOE/AC-T showed spatial memory retention during all probe trials. AC-T treatment significantly impaired spatial memory retention in the first and third probe trial (no platform). AC-T treatment decreased dendritic length in the Cornu Ammonis 1 (CA1) and dentate gyrus (DG) areas of the hippocampus while AC-T/MnBuOE maintained dendritic length. Comparative proteomic analysis revealed affected protein networks associated with cell morphology and behavior functions in both the AC-T and AC-T/MnBuOE treatment groups.

Doxorubicin-induced neurotoxicity is associated with acute alterations in synaptic plasticity, apoptosis, and lipid peroxidation

Cognitive deficits are commonly reported by patients following treatment with chemotherapeutic agents. Anthracycline-containing chemotherapy regimens are associated with cognitive impairment and reductions in neuronal connectivity in cancer survivors, and doxorubicin (Dox) is a commonly used anthracycline. Although it has been reported that Dox distribution to the central nervous system (CNS) is limited, considerable Dox concentrations are observed in the brain with co-administration of certain medications. Additionally, pro-inflammatory cytokines, which are overproduced in cancer or in response to chemotherapy, can reduce the integrity of the blood-brain barrier (BBB). Therefore, the aim of this study was to evaluate the acute neurotoxic effects of Dox on hippocampal neurons. In this study, we utilized a hippocampal cell line (H19-7/IGF-IR) along with rodent hippocampal slices to evaluate the acute neurotoxic effects of Dox. Hippocampal slices were used to measure long-term potentiation (LTP), and expression of proteins was determined by immunoblotting. Cellular assays for mitochondrial complex activity and lipid peroxidation were also utilized. We observed reduction in LTP in hippocampal slices with Dox. In addition, lipid peroxidation was increased as measured by thiobarbituric acid reactive substances content indicating oxidative stress. Caspase-3 expression was increased indicating an increased propensity for cell death. Finally, the phosphorylation of signaling molecules which modulate LTP including extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase, and Akt were increased. This data indicates that acute Dox exposure dose-dependently impairs synaptic processes associated with hippocampal neurotransmission, induces apoptosis, and increases lipid peroxidation leading to neurotoxicity.

Chemotherapy and cognition: comprehensive review on doxorubicin-induced chemobrain

Chemobrain refers to a common sequela experienced by a substantial subset of cancer patients exposed to chemotherapeutic treatment, a phenomenon that dramatically deteriorates the survivors' quality of life and prevents them from restoring their pre-cancer life. This review is intended to address the current knowledge regarding the mechanisms underlying the pathophysiology of the chemobrain phenomenon, with special focus on the antineoplastic agent ''doxorubicin'', which has been shown to be implicated in strenuous central neurotoxicity despite being-almost entirely-peripherally confined. Moreover, the assessment of the post-chemotherapy cognitive impairment in both human and animal subjects, and the potential pharmacotherapy and behavioral intervention strategies are reviewed.

Effects of Cyclophosphamide and/or Doxorubicin in a Murine Model of Postchemotherapy Cognitive Impairment

Postchemotherapy cognitive impairment, or PCCI, is a common complaint, particularly among breast cancer patients. However, the exact nature of PCCI appears complex. To model the human condition, ovariectomized C57BL/6J mice were treated intravenous weekly for 4 weeks with saline, 2 mg/kg doxorubicin (DOX), 50 mg/kg cyclophosphamide (CYP), or DOX + CYP. For the subsequent 10 weeks, mice were assessed on several behavioral tests, including those measuring spatial learning and memory. After sacrifice, hippocampal spine density and morphology in the dentate gyrus, CA1, and CA3 regions were measured. Additionally, hippocampal levels of total glutathione, glutathione disulfide, MnSOD, CuZnSOD, and cytokines were measured. Body weight decreased in all groups during treatment, but recovered post-treatment. Most behaviors were unaffected by drug treatment: Open field activity, motor coordination, grip strength, water maze and Barnes maze performance, buried food test performance, and novel object and object location recognition tests. There were some significant effects of CYP and DOX + CYP treatment during the initial test of home cage behavior, but these did not persist into the second and third test times. Density of stubby spines, but not mushroom or thin spines, in the dentate gyrus was significantly decreased in the DOX, CYP, and DOX + CYP treatment groups. There were no significant effects in the CA1 or CA3 regions. CuZnSOD levels were significantly increased in DOX + CYP-treated mice; other hippocampal antioxidant levels were unaffected. Most cytokines showed no treatment-related effects, but IL-1β, IL-6, and IL-12 were slightly reduced in mice treated with DOX + CYP. Although the animal model, route of exposure, and DOX and CYP doses used here were reflective of human exposure, there were only sporadic effects due to chemotherapeutic treatment.