Ranolazine Effectively Ameliorated Brain Pathologies and Cognitive Decline in Rats with Trastuzumap‐Induced Chemobrain

Abstract

AbstractBackgroundChemotherapy can increase survival rate of cancer patients. One of the chemotherapeutic drugs for breast cancer patients is trastuzumap (Trz). Chemotherapy not only helps to kill cancers, but it also causes several adverse effects in the patients, particularly in the brain, known as chemobrain. Chemobrain has been characterized by cognitive decline with brain mitochondrial dysfunction, hippocampal microglial activation, and loss of dendritic spines. Although several types of chemotherapy induce chemobrain, Trz‐induced chemobrain are not clearly elucidated. Ranolazine, a drug that is commonly used to treat the patients with chronic angina, shows benefits on cognitive function in doxorubicin‐induced chemobrain. However, the effects of ranolazine on brain mitochondrial function, hippocampal microglial function, hippocampal dendritic spines, and cognitive function in Trz‐induced chemobrain have never been investigated.MethodsEighteen male Wistar rats were randomly divided into two groups including control group (0.9% NSS, intraperitoneal (i.p.) injection, n=8) and Trz‐treated group (4 mg/kg for 7 days, i.p. injection, n=16). All Trz‐treated rats were randomly divided into two subgroups (n=8/ subgroup) to receive either vehicle (0.9% NSS, daily via oral gavage) or ranolazine (305 mg/kg/day, daily via oral gavage). At the end of experiment protocol, cognitive function was measured, and brains were obtained for further molecular investigation.ResultsThe results demonstrated that vehicle‐treated Trz‐rats significantly increased brain mitochondrial ROS production, increased brain mitochondrial membrane potential change, and increased brain mitochondrial swelling, suggesting brain mitochondrial dysfunction (p<0.05, Figure 1). These parameters were attenuated in ranolazine‐treated Trz‐rats (p<0.05, Figure 1). In addition, the microglial activation was found in vehicle‐treated Trz‐rats as indicated by increased the number of microglial cells, which was suppressed by the ranolazine treatment (p<0.05, Figure 1). Consistently, the dendritic spine density decreased in vehicle‐treated Trz‐rats, leading to cognitive decline (p<0.05, Figure 1). Ranolazine‐treated Trz‐rats showed an increase in dendritic spine density, resulting in the improvement of cognitive function (p<0.05, Figure 1).ConclusionsAll findings suggest that ranolazine effectively ameliorated cognitive decline in rats with Trz‐induced chemobrain. The novel findings obtained from the present study provided the therapeutic strategies which can be translated into clinical settings for better preventing chemobrain in the future.