Galantamine mitigates neurotoxicity caused by doxorubicin via reduced neuroinflammation, oxidative stress, and apoptosis in rat model

OBJECTIVE

Doxorubicin (DXR) is commonly used as a drug for cancer treatment. However, there have been reports of neurotoxicity associated with chemotherapy. Galantamine (GLN) is a medication that inhibits cholinesterase activity, providing relief from the neurotoxic effects commonly seen in individuals with Alzheimer's disease. This study explored the potential ameliorative effect of GLN on brain neurotoxicity induced by DXR.

MATERIALS AND METHODS

Forty rats were allocated into four separate groups for a study that lasted for a period of fourteen days. The control group was given normal saline, DXR group was given 5 mg/kg DXR every three days (cumulative dose of 20 mg/kg) through intraperitoneal injection. The GLN group was given 5 mg/kg GLN through oral gavage daily, while the DXR+GLN group was given DXR+GLN simultaneously. An analysis of brain proteins using ELISA to assess apoptosis through the concentration of inflammation and oxidative injury markers.

RESULTS

The DXR treatment led to increased neuroinflammation by elevation of nuclear factor kappa B (NF-κB), and cyclooxygenase-2 (COX-2), oxidative stress by rise of malondialdehyde (MDA), and decline of superoxide dismutase (SOD), and no changes in catalase and glutathione (GSH), cell death by elevation of Bax and caspase-3 and reduced Bcl-2, and increase lipid peroxidation, impaired mitochondrial function. When GLN is administered alongside DXR, it has been observed to positively impact various biological markers, including COX-2, NF-κB, MDA, SOD, Bax, Bcl-2, and caspase-3 levels. Additionally, GLN improves lipid peroxidation and mitochondrial activity.

CONCLUSIONS

DXR therapy in rats results in the development of neurotoxicity, and a combination of GLN can recover these toxicities, suggesting GLN promising evidence for mitigating the neurotoxic effects induced by DXR.

Metformin's effect on male rats experiencing CMF-induced neurotoxicity

OBJECTIVE

Numerous cancers are treated with the chemotherapy drugs cyclophosphamide (CP), methotrexate (MT), and fluorouracil (FU). However, it should be noted that neurotoxicity is a possible side effect of chemotherapy. The pharmaceutical agent metformin (MTF) is used to control type 2 diabetes. The administration of MTF has been documented to exhibit a reduction in specific toxic effects associated with chemotherapy. The primary purpose of this research was to examine whether MTF could mitigate the neurotoxicity brought on by cranial magnetic field (CMF).

MATERIALS AND METHODS

A cohort of forty male rats was divided into four distinct groups, with ten animals in each. We classified them as either saline, MTF, CMF, or CMF+MTF. The rats in the experiment group received two doses of CMF via intraperitoneal injection and were also given MTF in their drinking water at a concentration of 2.5 mg/mL on a daily basis. Brain tissue was obtained for ELISA of Bax, Bcl-2, and caspase-3 expression, as well as to determine NMDA and AMPA receptor mRNA expression by real-time polymerase chain reaction (RT-PCR) analysis.

RESULTS

Expression of AMPAR, NMDAR, Bax, Bcl-2, and caspase-3 was not notably different between the saline and MTF groups. In contrast, mRNA expression for AMPAR, NMDAR, Bax, and caspase-3 was notably upregulated in the CMF group, while Bcl-2 was downregulated. The co-administration of MTF and CMF did not mitigate these side effects.

CONCLUSIONS

neurotoxicity was induced in rats by CMF treatment, but the elevation of the glutamatergic system and the elevation of apoptotic proteins were not prevented by the MTF co-treatment.

Nilotinib treatment induces cognitive impairment by elevating hippocampal oxidative stress in rats

OBJECTIVE

Protein tyrosine kinases (TKs) play a critical role in the regulation of various functions of a cell, including cellular proliferation, differentiation, and growth, and inhibitors of TKs have emerged as next-generation therapeutic agents in various types of cancer. Nilotinib, one of the TK inhibitors used to treat chronic myeloid leukemia, has been poorly investigated for its potential impact on memory function despite its ability to cross the blood-brain barrier (BBB). Thus, in this study, we investigated the effect of nilotinib on hippocampal-dependent cognitive functions and its potential mechanisms.

MATERIALS AND METHODS

Wistar albino male rats were divided into three groups of 10 each. The animals of group I (normal control) received drinking water only, while groups II and III were treated with nilotinib at doses of 15 mg/kg and 30 mg/kg, p.o. respectively, once daily for two weeks. The animals were subjected to behavioral tests after completion of drug treatment for the assessment of cognitive function using the Y-maze, novel object recognition (NOR) test, and elevated plus maze (EPM). The animals were euthanized after the estimation of blood glucose, and hippocampal tissues were dissected for the estimation of markers of oxidative stress.

RESULTS

Nilotinib produced impairment of memory function on the Y-maze, NOR test, and EPM. These results were also supported by a significant increase in glutathione (GSH), malondialdehyde (MDA), Akt, glycogen synthase kinase-3 beta (GSK3β), and total antioxidant capacity (TAC) in hippocampal tissue without altering the blood glucose level.

CONCLUSIONS

Nilotinib treatment produced significant impairment of cognitive function by inducing oxidative stress in the hippocampal tissue of rats.

Pioglitazone ameliorates doxorubicin-induced hypothyroidism and cardiotoxicity in rat models

OBJECTIVE: The anticancer drug doxorubicin (DOX) is effective but is associated with complications such as hypothyroidism and cardiotoxicity. Pioglitazone (PIO), which is used to treat diabetes mellitus, has shown potential for treating hypothyroidism and cardiac dysfunction. Therefore, this study explores whether PIO can also ameliorate DOX-induced hypothyroidism and cardiotoxicity. MATERIALS AND METHODS: Forty female Wistar rats were separated into control and three treated groups (DOX, PIO, and DOX+PIO), and their blood samples were examined for the thyroid hormones, including thyroid-stimulating hormone (TSH), thyroxine in total and free forms (T4 and FT4, respectively), and triiodothyronine in total and free forms (T3 and FT3, respectively), and the cardiotoxicity biomarkers [troponin I, creatine kinase (CK), and creatine kinase-myocardial band (CK-MB)]. RESULTS: The control and PIO groups did not exhibit significant alterations in any of the examined hormones and markers. In contrast, in the DOX group, T4, FT4, T3, and FT3 levels decreased significantly, whereas troponin I, CK, and CK-MB levels increased significantly, but no significant changes were detected in TSH levels. PIO co-treatment ameliorated these effects of DOX significantly in FT4, FT3, and troponin I. CONCLUSIONS: PIO may provide protection against hypothyroidism and cardiotoxicity caused by DOX treatment, by significant reversal of FT4, FT3, and troponin I levels.

Graphical Abstract

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Effects of CMF and MET on glutamate and dopamine levels in the brain, and their impact on cognitive function

OBJECTIVE

Chemotherapy can cause cognitive impairment in cancer survivors. CMF, the combination of cyclophosphamide (CYP), methotrexate (MTX), and 5-fluorouracil (5-FU), is employed for the treatment of several types of cancers, such as metastatic breast cancer. Metformin (MET) is an antidiabetic medication used to treat type 2 diabetes that can reportedly alleviate some toxic effects. In the current study, we investigated the ability of MET to alleviate the effects of CMF in neuronal toxicity.

MATERIALS AND METHODS

Rats were treated with two doses of CMF (intraperitoneal injection) and MET (in the daily drinking water). Rats were subjected to fear conditioning memory tests to evaluate memory function following treatment, and brain samples were collected and homogenized using neuronal lysis buffer for assessment of glutamate and dopamine levels by high-performance liquid chromatography (HPLC).

RESULTS

Fear conditioning memory tests revealed a significant reduction in memory function in CMF and CMF+MET groups vs. controls, but no significant change in MET groups vs. controls was detected. Similarly, CMF and CMF+MET groups revealed a significant increase in glutamate and dopamine levels in the brain of MET, CMF, and MET+CMF groups vs. controls based on HPLC results. In addition, although glutamate and dopamine levels were increased, levels varied between groups, with highest levels in the CMF+MET group.

CONCLUSIONS

Our results demonstrate that cognitive impairment in CMF and CMF+MET groups could result from increased glutamate and dopamine levels in the brain, leading to brain toxicity and failure of MET to alleviate the toxic effects of CMF.

Elucidating the mechanism underlying cognitive dysfunction by investigating the effects of CMF and MET treatment on hippocampal neurons

OBJECTIVE

Chemotherapy causes long-term cognitive impairment in cancer survivors. A combination of cyclophosphamide (CYP), methotrexate (MTX), and 5-fluorouracil (5-FU) (i.e., CMF) is widely used for cancer treatment. Metformin (MET), an oral antidiabetic drug, confers protection against the adverse effects of chemotherapeutic agents, such as CYP. To elucidate the potential mechanism underlying cognitive dysfunction, we investigated the impact of CMF and MET treatment on the activities of mitochondrial respiratory chain complexes I and IV, as well as lipid peroxidation, in hippocampal neurons.

MATERIALS AND METHODS

Hippocampal neurons (H19-7) cells were treated for 24 h with MET (0.5 mM) alone; CYP (1 µM), MTX (0.5 µM), and 5-FU (1 µM); and MET (0.5 mM) + CYP (1 µM), MTX (0.5 mM), and 5-FU (1 µM). A 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide assay was performed to evaluate cell survival. Neurons were collected and homogenized in a neuronal lysis buffer to assess mitochondrial complexes (I and IV) activity and lipid peroxidation.

RESULTS

Compared to the control, MET-treated cells showed no significant difference in survival rate; however, CMF- and CMF + MET-treated cells showed a significant reduction in survival rate. In addition, relative to the control, CMF- and CMF + MET-treated cells showed a reduction in mitochondrial complex I activity, whereas no significant changes were observed in mitochondrial complex IV activity. MET-treated cells showed no significant differences in lipid peroxidation, but CMF- and CMF + MET-treated cells showed a slight increase in lipid peroxidation.

CONCLUSIONS

The reduction in the activity of mitochondrial complex I and a slight increase in lipid peroxidation levels may explain the cognitive impairment following CMF and MET treatments.

Organophosphates modulate tissue transglutaminase activity in differentiated C6 neural cells

OBJECTIVE

The organophosphate compounds chlorpyrifos (O, O-diethyl O-[3,5,6-trichloro-2-pyridinyl] phosphorothioate, CPF) and phenyl saligenin phosphate (PSP) have been widely implicated in developmental neurotoxicity and neurodegeneration. However, the underlying mechanism remains unclear. Transglutaminase (TG)2 is a calcium ion (Ca2+)-dependent enzyme with an important role in neuronal cell outgrowth and differentiation and in neurotoxin activity and is modulated by organophosphates.

MATERIALS AND METHODS

We studied TG2 activity modulation by CPO and PSP during differentiation in C6 glioma cells. We studied the effects of CPO or PSP treatment with or without the TG2 inhibitor Z-DON and identified potential TG2 protein substrates via mass spectrometry.

RESULTS

PSP and CPO did not affect cell viability but affected TG2 activity in differentiating cells. Our results indicate that the organophosphate-induced amine incorporation activity of TG2 may have a direct effect on neuronal outgrowth, differentiation, and cell survival by modifying several essential microtubule proteins, including tubulin. Inhibiting TG2 reduced neurite length but not cell survival.

CONCLUSIONS

TG2 inhibitors can protect against organophosphate-induced neuropathy and could be used for developing novel therapeutic strategies for treating brain cancer and neurodegenerative disorders.

Associations of healthcare providers' awareness, perception, and knowledge of chemotherapy-induced cognitive impairment and their intentions to provide information about it to patients

OBJECTIVE

Most recent oncology studies support the existence of chemotherapy-induced cognitive impairment. This study's objective was to evaluate the power of healthcare providers' knowledge, awareness, and perception of memory impairment caused by chemotherapeutic agents, as predictors of their intentions to convey information about this side effect to patients.

MATERIALS AND METHODS

A cross-sectional online survey with 32 questions and seven domains was distributed. The domains included questions about healthcare providers' behaviors, norms, attitudes, awareness, perceptions, and knowledge about chemotherapeutic agent-induced cognitive impairment and their intentions to inform patients about these side effects. Descriptive and inferential statistics were calculated to analyze associations.

RESULTS

A total of 207 healthcare providers completed the survey. Their mean age was 31 (±7.8) years and most of them were physicians (43.5%). Positive relationships were found between healthcare providers' attitudes (β=0.239, p<0.001), subjective norms (β=0.219, p<0.001), behavioral control (β=0.284, p<0.001), and intentions to provide information to patients. Their awareness was positively associated with their age (β=0.127, p<0.001), and their (or their relatives') receipt of chemotherapeutic agents (β=1.363, p=0.04); however, a negative relationship was found with physician specialists (β=-2.659, p<0.001) and Saudi nationality (β=-2.919, p<0.001). A negative correlation was found between healthcare givers' perceptions and physician specialists (β=-1.487, p=0.003), and a positive association with participants' total knowledge (β=0.765, p<0.001). Univariate linear regression analysis of participants' knowledge showed a negative relationship with Saudi nationality (β= -0.835, p<0.001) and physician specialists (β= -0.519, p=0.003).

CONCLUSIONS

Providers' low scores on awareness, perceptions, and knowledge of these side effects of treatment highlight a need for strategic educational programs that meet patients' needs and improve their quality of life.

Mechanisms underlying cognitive impairment induced by prenatal nicotine exposure: a literature review

Human and animal studies have conclusively shown that prenatal nicotine exposure alters fetal brain development and causes persistent impairment in the cognitive function of offspring. However, the mechanisms underlying the effect of prenatal nicotine exposure on cognitive function in offspring are still unclear. The objective of this review is to discuss the published studies on the mechanisms underlying the effects of prenatal nicotine exposure on cognitive impairment and discuss the potential mechanisms of action. The findings of the reviewed studies show that the main mechanisms involved are alteration in the composition of nicotinic acetylcholine receptor subunits, increase in surface expression of the glutamate receptor subunit GluR2, a reduction in neurogenesis, alteration of Akt and ERK1/2 activity, and mitochondrial dysfunction in the hippocampus and cortex. These pathways could shed light on future molecular markers and therapeutic targets for the prevention and treatment of cognitive dysfunction induced by prenatal nicotine exposure.

Recent progress in the elucidation of the mechanisms of chemotherapy-induced cognitive impairment

The term "chemobrain" refers to the cognitive dysfunction that occurs after chemotherapy, and it is also known as chemotherapy-induced cognitive impairment or "chemofog". The aim of this review is to bring together the findings of existing literature on the topic and summarize the current knowledge on the potential mechanisms of chemobrain. According to the reviewed studies, the mechanisms by which chemotherapy could cause chemobrain include disruption of hippocampal cell proliferation and neurogenesis, hormonal changes, increased oxidative stress and reactive oxygen species production, chronic increase in inflammation, and alterations in synaptic plasticity and long-term potentiation. While the effects of inflammation and oxidative stress on neurogenesis and their role in chemotherapy-induced cognitive impairment have been widely studied, the chemotherapy-induced cognitive impairment mechanisms that involve mitochondrial dysfunction, estrogen dysregulation, and increased transglutaminase 2 are still unclear. Further studies on these mechanisms are necessary to understand the effects of chemotherapy at the cellular and molecular level and facilitate the development of preventive and therapeutic strategies against chemotherapy-associated cognitive impairment or chemobrain.

Ameliorative effect of metformin on cyclophosphamide-induced memory impairment in mice

OBJECTIVE

Cyclophosphamide (CYP) is a chemotherapeutic agent that is widely used as an adjuvant cancer treatment. Unfortunately, this drug is associated with secondary side effects, including cognitive impairment up to 70% of cancer survivors. The mechanism of this memory impairment is unclear. Thus, to understand the cognitive impairments caused by this chemotherapeutic agent, a clinically relevant dose to cancer treatment was used in mice to establish the chemobrain models, and the spatial memory of these mice was assessed using multiple behavior tests. In addition, metformin (MET) is widely used as an anti-diabetic drug and protects against oxidative stress and hepatotoxicity. Thus, this study tested the protective effects of MET in the chemobrain models.

MATERIALS AND METHODS

Four groups of mice, which weighed about 18-30 g, were collected and divided into 4 groups: control, CYP, MET, and CYP+MET groups. A 100 mg/kg dose of CYP was administered intraperitoneal (on alternate days) for a total of 4 doses. MET was dissolved in the mice's drinking water bottles at a 5 mg/ml concentration from day zero to the end of the treatment period. The mice's memory was tested using hippocampal-dependent tests, including the Y-maze, novel object recognition, and elevated plus maze tests. These tests were performed for three consecutive days after 24 h of the last dose of CYP.

RESULTS

The mice treated with CYP exhibited a decline in memory function in all the behavioral test studies, and this decline was significant in the Y-maze test. However, this decline was rescued by MET administration.

CONCLUSIONS

The clinically relevant model suggests that CYP treatment causes a decline in mice models spatial memory that might be improved by MET administration.

Effect of inhaled waste anaesthetic gas on blood and liver parameters among hospital staff

A significant health risk exists within a section of health workers that are exposed to anaesthetic gas and vapours, found in the atmosphere of treatment or operating rooms. These compounds are classified as waste anaesthetic gases (WAG). The present study aimed at identifying alterations in hepatic and haematological parameters occurring as a result of chronic exposure to WAG potentially affecting the health of team members working in hospitals. Therefore, operating room operatives, vulnerable to long-standing WAG exposure, were recruited for this study. Sevoflurane anaesthesia metabolites (inorganic fluoride and hexafluoroisopropanol (HFIP)), haematological indices and liver toxicity markers (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transferase and osteopontin) were measured. The collected results showed increased plasma inorganic fluoride, HFIP and liver toxicity markers, as well as disturbances in haematological parameters. In conclusion, exposure to halogenated inhalational anaesthetics, in general, and Sevoflurane, in particular, induces alterations in hepatic markers and haematological indices.

Silencing of tissue factor by antisense deoxyoligonucleotide mitigates thioacetamide-induced liver injury

BACKGROUND

Retinoid receptors (RRs), RAR-α and RXR-α, work as transcription factors that regulate cell growth, differentiation, survival, and death. Hepatic stellate cells (HSCs) store retinoid and release its RRs as lipid droplets upon their activation.

PURPOSE

We test the hypothesis that loss of retinoid receptors RAR-α and RXR-α from HSCs is dependent on tissue factor (TF) during thioacetamide (TAA)-induced liver injury.

METHODS

Liver toxicity markers, TF, fibrin, cleaved caspase-3, and cyclin D1 as well as histopathology were investigated.

RESULTS

Increased TF, fibrin, cleaved caspase-3, and cyclin D1 protein expression is seen in zone of central vein after TAA injection compared with vehicle-treated mice. A strong downregulation of RAR-α and RXR-α is seen in TAA-induced liver injury. In addition, histopathological obliteration and pericentral expression of cleaved caspase 3 and cyclin D1 are observed after TAA injection compared with the normal vehicle-treated mice. No changes have been seen in TAA/TF-sense (SC) in whole parameters compared with TAA-treated animals. TAA/TF-antisense (AS)-treated mice show normal expression of all parameters and normal histopathological features when compared with the control mice. In conclusion, this study declares that the strong downregulation of RAR-α and RXR-α may cause liver injury and particularly activation of HSCs in TAA-induced toxicity. TF-AS treatment not only downregulates TF protein expression but also alleviates loss of liver RAR-α and RXR-α and suppresses the activated apoptosis signals in TAA-induced liver toxicity. Finally, TF and RAR-α/RXR-α are important regulatory molecules in TAA induced acute liver injury.