الفهرس 
Brain areas involved in memoryOnly 14 pages are availabe for public view
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Abstract
Chemotherapy is the most commonly implemented strategy in cancer treatment, often used in conjunction with radiotherapy, surgery and/or hormonal treatment. Although chemotherapy is beneficial against several malignancies, it also affects healthy cells causing several adverse effects among which CNS toxicity, including cognitive impairment, is of particular concern. This cognitive impairment, often referred to as chemobrain, is characterized by the impairment of patients’ memory, learning, attention, concentration, reasoning, processing speed, executive functions, and visuo-spatial skills. This may occur with various types of solid tumors treatment, mainly breast, lung, prostate, and ovarian cancers among others. Cognitive impairment varies widely among patients, being transient with mild reversible manifestations (occurring during and after discontinuation of chemotherapy) in most cases.
Doxorubicin (DOX) is a prominent mainstay member of the anthracycline antineoplastic agents; it is one of the most potent FDA-approved agents for the treatment of diverse types of tumors. Preclinical studies verified deficits in hippocampal-related learning and memory in animals treated with DOX. Administration of DOX was reported to induce biochemical alterations that encompass increased levels of peripheral inflammatory cytokines and brain oxidative damage.
Caffeic acid phenethyl ester (CAPE), a natural polyphenolic compound, is reputable for its potent antioxidant, anti-inflammatory, antitumor and neuroprotective properties. Since CAPE was shown to counteract neuronal inflammation, oxidative stress, mitochondrial impairment and neuronal cell death in different preclinical models, it is anticipated that it can afford protection against DOX-induced oxidative impairment through an interplay of various pathways.
The aim of the current study, therefore, was to test the hypothesis that CAPE can protect against DOX-induced chemobrain in Sprague-Dawley rats and investigate the potential underlying mechanisms for the potential protection.
Experimental design:
Rats were randomly divided into five groups (n=12) and treated for 4 weeks as follows:
• The first group served as control and received the drug vehicles, saline and tween 80/sunflower oil (2% tween), i.p.
• The second group received DOX dissolved in saline (2 mg/kg/week, i.p.) for 4 weeks (1 dose/week).
• The third and fourth groups received CAPE (10 and 20 μmol/kg/day, respectively, i.p., 5 days per week), dissolved in tween 80 /sunflower oil (2% tween) then after 1 hour from CAPE administration, DOX was administered (2 mg/kg/week, i.p.).
• The fifth group received CAPE alone (20 μmol/kg/day, i.p., 5 days per week).
Rats were euthanized by cervical dislocation, decapitated, whole brains were excised, and hippocampi and prefrontal cortices were dissected out and either stored at −80 °C for neurochemical analyses or fixed in 10% formalin for subsequent histopathological examinations.
The following parameters were investigated:
• Morris Water Maze (MWM)- time spent in platform quadrant.
• Step-through passive avoidance (PA).
• Locomotor activity test (LA).
• Assessment of neurodegeneration: Hematoxylin and eosin (H and E) and toluidine blue staining.
• Oxidative stress markers: reduced glutathione (GSH) and malondialdehyde (MDA) in hippocampal and prefrontal cortical tissues.
• Inflammatory markers: Cyclooxygenase II (COX-II), NF-ĸB p65 nuclear levels and Tumor necrosis factor-alpha (TNF-α) in hippocampal and prefrontal cortical tissues.
• Astrocyte activation marker: Glial fibrillary acidic protein (GFAP) in hippocampal and prefrontal cortical tissues.
• Acetylcholine level in hippocampal and prefrontal cortical tissues.
• Apoptotic marker: active caspase-3 in hippocampal and prefrontal cortical tissues.
Results:
• Spatial learning and memory were assessed using MWM test. Rats co-treated with either CAPE 10 or CAPE 20 showed improved cognitive function as evidenced by spending longer time in the target quadrant compared to DOX-treated group. Rats treated with CAPE 20 alone showed no significant difference compared to the control group regarding escape latency and target quadrant time.
• In the step-through PA paradigm, CAPE (10 and 20 μmol/kg/day, respectively, i.p., 5 days per week) reversed DOX-induced amnesia as evident by restoration of the normal step-through latency. CAPE 20 alone did not cause any changes in the step-through latency compared to the control group.
• CAPE and/or DOX did not affect the locomotor activity of the treated rats.
• Treatment with CAPE (10 and 20 μmol/kg/day, respectively, i.p., 5 days per week) reversed DOX-induced hippocampal and prefrontal cortical neurodegenerative changes.
• The extent of neurodegeneration with both hippocampal (CA1 and CA3) and prefrontal cortical tissues was further assessed using toluidine blue staining. Assessment of hippocampal and prefrontal cortical neuronal population of DOX-treated animals displayed a loss of the histological architecture as evidenced by the presence of hyperchromatic neurons with darkened cytoplasm and pyknotic nuclei altogether with loss of rounded framework of normal neurons. However, the concurrent CAPE treatment restored the normal neuronal features as manifested by the rounded neuronal build, euchromatic cytoplasm and well-defined nuclei. CAPE alone-treated group showed no deviation from the normal histological architecture of the vehicle-treated group.
• CAPE reverted DOX-induced hippocampal and prefrontal cortical oxidative stress as evidenced by normalization of GSH and MDA levels.
• CAPE halted DOX-induced hippocampal and prefrontal cortical inflammatory insult as shown by statistically significant down-surge expression of GFAP, COX-II, NF-ĸB p65 and TNF-α.
• The level of ACh was significantly decreased in the hippocampal and prefrontal cortical tissues of DOX-treated rats compared to the control group. Co-treatment with CAPE 10 and CAPE 20 resulted in significant higher hippocampal and prefrontal cortical ACh compared to DOX-alone group.
• CAPE demonstrated efficient antiapoptotic activity where it significantly reverted DOX-induced activation of caspase-3.
In conclusion, the present study provides evidence that 4 weekly systemic injections of DOX (2mg/kg) development cognitive deficits. CAPE, a natural polyphenolic compound, could present a promising anti-amnestic and neuroprotective agent which could guard against DOX-induced chemobrain. The underlying mechanisms beyond CAPE neuroprotective activity as evidenced by neurobehavioral tests, histopathological examination and toluidine blue staining could be at least partly attributed to a myriad of actions including antioxidant, anti-inflammatory and anti-apoptotic activities. Accordingly, the current study serves as a preclinical evidence of the neuroprotective impact of CAPE supplementation in DOX-treated cancer patients.