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.

Comparative evaluation of doxorubicin, cyclophosphamide, 5-fluorouracil, and cisplatin on cognitive dysfunction in rats: Delineating the role of inflammation of hippocampal neurons and hypothyroidism

Chemotherapeutic agents such as doxorubicin, cyclophosphamide, fluorouracil, and cisplatin are commonly used to treat a variety of cancers and often result in chemobrain, which manifests as difficulties in learning and memory processes that can persist in the years following treatment. The current study aims to evaluate the cognitive function following treatment with these agents and the underlying mechanisms using a rat model of neuroinflammation and possible implication of thyroid toxicity in chemotherapy induced cognitive dysfunction. Wistar female rats were treated with a single dose of doxorubicin (DOX, 25 mg/kg), 5-fluorouracil (5-FU, 100 mg/kg), cisplatin (8 mg/kg), and cyclophosphamide (CYP, 200 mg/kg) by intraperitoneal injection. The cognitive performance of rats was then evaluated in spatial memory tasks using the Y-maze, novel object recognition (NOR), and elevated plus maze (EPM) tests. Serum levels of thyroid hormones (T3, T4, FT3, and FT4) and thyroid stimulating hormone (TSH) were measured, followed by estimation of TNFα, IL-6, and IL-1β in the hippocampal tissue. Results revealed that all the chemotherapeutic agents produced impairment of cognitive function, and significant increase of pro-inflammatory cytokines such as TNFα, IL-6 and IL-1β in the hippocampal tissues. There was a significant reduction in thyroid hormones (T3, FT3, and T4) and an increase in thyroid stimulating hormone (TSH) in serum, which may also have contributed to the decline in cognitive function. In conclusion, DOX, 5-FU, CYP, and cisplatin produces impairment of spatial memory possibly by inflammation of hippocampal neurons and endocrine disruption (hypothyroidism) in rats.

Molecular insights into the pathogenic impact of vitamin D deficiency in neurological disorders

Neurological disorders are the major cause of disability, leading to a decrease in quality of life by impairing cognitive, sensorimotor, and motor functioning. Several factors have been proposed in the pathogenesis of neurobehavioral changes, including nutritional, environmental, and genetic predisposition. Vitamin D (VD) is an environmental and nutritional factor that is widely distributed in the central nervous system's subcortical grey matter, neurons of the substantia nigra, hippocampus, thalamus, and hypothalamus. It is implicated in the regulation of several brain functions by preserving neuronal structures. It is a hormone rather than a nutritional vitamin that exerts a regulatory role in the pathophysiology of several neurological disorders, including Alzheimer's disease, Parkinson's disease, epilepsy, and multiple sclerosis. A growing body of epidemiological evidence suggests that VD is critical in neuronal development and shows neuroprotective effects by influencing the production and release of neurotrophins, antioxidants, immunomodulatory, regulation of intracellular calcium balance, and direct effect on the growth and differentiation of nerve cells. This review provides up-to-date and comprehensive information on vitamin D deficiency, risk factors, and clinical and preclinical evidence on its relationship with neurological disorders. Furthermore, this review provides mechanistic insight into the implications of vitamin D and its deficiency on the pathogenesis of neurological disorders. Thus, an understanding of the crucial role of vitamin D in the neurobiology of neurodegenerative disorders can assist in the better management of vitamin D-deficient individuals.

An insight into the implications of estrogen deficiency and transforming growth factor β in antiepileptic drugs-induced bone loss

There have been a number of reports that chronic antiepileptic drug (AEDs) therapy is associated with abnormal bone and calcium metabolism, osteoporosis/osteomalacia, and increased risk of fractures. Bony adverse effects of long term antiepileptic drug therapy have been reported for more than four decades but the exact molecular mechanism is still lacking. Several mechanisms have been proposed regarding AEDs induced bone loss; Hypovitaminosis D, hyperparathyroidism, estrogen deficiency, calcitonin deficiency. Transforming growth factor-β (TGF- β) is abundant in bone matrix and has been shown to regulate the activity of osteoblasts and osteoclasts in vitro. All isoforms of TGF- β are expressed in bone and intricately play role in bone homeostasis by modulating estrogen level. Ovariectomised animal have shown down regulation of TGF- β in bone that could also be a probable target of AEDs therapy associated bone loss. One of the widely accepted hypotheses regarding the conventional drugs induced bone loss is hypovitaminosis D which is by virtue of their microsomal enzyme inducing effect. However, despite of the lack of enzyme inducing effect of certain newer antiepileptic drugs, reduced bone mineral density with these drugs have also been reported. Thus an understanding of bone biology, pathophysiology of AEDs induced bone loss at molecular level can aid in the better management of bone loss in patients on chronic AEDs therapy. This review focuses mainly on certain new molecular targets of AEDs induced bone loss.

An in-silico analysis of ivermectin interaction with potential SARS-CoV-2 targets and host nuclear importin α

Ivermectin (IVM) is a broad-spectrum antiparasitic agent, having inhibitory potential against wide range of viral infections. It has also been found to hamper SARS-CoV-2 replication in vitro, and its precise mechanism of action against SARS-CoV-2 is yet to be understood. IVM is known to interact with host importin (IMP)α directly and averts interaction with IMPβ1, leading to the prevention of nuclear localization signal (NLS) recognition. Therefore, the current study seeks to employ molecular docking, molecular mechanics generalized Born surface area (MM-GBSA) analysis and molecular dynamics simulation studies for decrypting the binding mode, key interacting residues as well as mechanistic insights on IVM interaction with 15 potential drug targets associated with COVID-19 as well as IMPα. Among all COVID-19 targets, the non-structural protein 9 (Nsp9) exhibited the strongest affinity to IVM showing -5.30 kcal/mol and -84.85 kcal/mol binding energies estimated by AutoDock Vina and MM-GBSA, respectively. However, moderate affinity was accounted for IMPα amounting -6.9 kcal/mol and -66.04 kcal/mol. Stability of the protein-ligand complexes of Nsp9-IVM and IMPα-IVM was ascertained by 100 ns trajectory of all-atom molecular dynamics simulation. Structural conformation of protein in complex with docked IVM exhibited stable root mean square deviation while root mean square fluctuations were also found to be consistent. In silico exploration of the potential targets and their interaction profile with IVM can assist experimental studies as well as designing of COVID-19 drugs.

Effect of escitalopram on cardiomyopathy-induced anxiety in mice

The present study was aimed to evaluate the effect of escitalopram on anxiety following doxorubicin (DOX)-induced cardiomyopathy, a rodent model for heart failure (HF), in mice. The study was carried out in Swiss albino mice. DOX was used at a dose of 10 mg/kg intravenously. Escitalopram was administered at the doses of 10 and 20 mg/kg orally for 7 days pre- and 7 days post-DOX. Anxiety was measured on day 8 and on day 14 using elevated plus maze and Vogel's conflict test. On day 14, serum lactate dehydrogenase (LDH) was estimated. The mice were then killed and their hearts were dissected out for the estimation of malondialdehyde (MDA) and for the transmission electron microscopic (TEM) studies. Our results showed that the DOX administration induced cardiomyopathy in mice. This was evidenced by the increased levels of serum LDH and tissue MDA and was also confirmed by TEM. Escitalopram (20 mg/kg) not only reversed the anxiety-like effects induced by DOX but also DOX-induced increase in LDH and MDA as well as the morphological alterations induced by DOX in TEM studies. Escitalopram, thus, appears to be a good candidate for alleviating anxiety in patients with HF.

Effect of alprazolam on anxiety and cardiomyopathy induced by doxorubicin in mice

Anxiety following heart failure (HF) and/or myocardial infarction (MI) can impede recovery and constitute a major risk factor for further cardiac events. The present study was aimed to evaluate anxiety following doxorubicin (DOX)-induced cardiomyopathy, a rodent model for HF, in mice. Furthermore, the study investigated the effect of alprazolam on anxiety and cardiomyopathy in this model. The study was carried out in Swiss albino mice. DOX was used at a dose of 10 mg/kg i.v. Alprazolam was administered at doses of 0.5, 1 and 2 mg/kg po for 7 days' pre- and 7 days' post-DOX. Anxiety was measured on day 8 and on day 14 using elevated plus maze and Vogel's conflict test. On 14th day, serum lactate dehydrogenase (LDH) was estimated. The mice were then killed and hearts were dissected out for estimation of thiobarbituric acid reactive substance and Transmission Electron Microscopy (TEM) studies. Our results showed that DOX administration induced cardiomyopathy in mice. This was evidenced by an increased serum LDH and tissue malondialdehyde (MDA) and was confirmed by TEM studies. Alprazolam treatment for 14 days dose dependently reversed DOX-induced increase in LDH and MDA as well as the morphological alterations induced by DOX in TEM studies. Furthermore, alprazolam also reversed the anxiety-like effects induced by DOX in both the tests for anxiety. Thus, alprazolam appears to be a good candidate for alleviating anxiety in patients following MI or HF.