Neo-adjuvant chemotherapy with cisplatin induces low expression of NMDA receptors and postoperative cognitive impairment

Artificial and natural interventions for chemotherapy- and / or radiotherapy-induced cognitive impairment: A systematic review of animal studies

BACKGROUND

Cancer survivors frequently experience cognitive impairments. This systematic review assessed animal literature to identify artificial (pharmaceutical) or natural interventions (plant/endogenously-derived) to reduce treatment-related cognitive impairments.

METHODS

PubMed, EMBASE, PsycINFO, Web of Science, and Scopus were searched and SYRCLE's tool was used for risk of bias assessment of the 134 included articles.

RESULTS

High variability was observed and risk of bias analysis showed overall poor quality of reporting. Results generally showed positive effects in the intervention group versus cancer-therapy only group (67% of 156 cognitive measures), with only 15 (7%) measures reporting cognitive impairment despite intervention. Both artificial (61%) and natural (75%) interventions prevented cognitive impairment. Artificial interventions involving GSK3B inhibitors, PLX5622, and NMDA receptor antagonists, and natural interventions utilizing melatonin, curcumin, and N-acetylcysteine, showed most consistent outcomes.

CONCLUSIONS

Both artificial and natural interventions may prevent cognitive impairment in rodents, which merit consideration in future clinical trials. Greater consistency in design is needed to enhance the generalizability across studies, including timing of cognitive tests and description of treatments and interventions.

Agomelatine attenuates cisplatin-induced cognitive impairment via modulation of BDNF/TrkB signaling in rat hippocampus

Cisplatin is a drug used effectively in the treatment of malignant tumors. However, cisplatin has many side effects, including cognitive impairment. Agomelatine, a synthetic melatonin analogue, is an important antidepressant. Increasing evidence has shown that agomelatine may be a potential neuroprotective agent. The aim of this study was to investigate the effect of agomelatine on learning and memory functions in cisplatin-induced cognitive impairment in a rat model. Male rats were administered agomelatine and cisplatin for 4 weeks. Neurobehavioral tests were performed at the end of the 4th week. After behavioral tests, rats were euthanized and BDNF, TNF, IL-1β, MDA and GSH levels were measured in hippocampal homegenates by ELISA. In addition, nNOS and TrkB receptor activity were measured immunohistochemically. The results showed that agomelatine significantly improved cognitive functions in spatial memory tests in rats with cisplatin-induced cognitive impairment. In addition, agomelatine treatment positively affected the discrimination index (DI). On the other hand, agomelatine treatment elevated cisplatin-suppressed hippocampal BDNF levels. Agomelatine treatment reduced cisplatin-induced neuroinflammation by suppressing TNF and IL-1β levels. Similarly, agomelatine reduced oxidative stress in the hippocampus. Histological findings showed that agomelatine treatment reduced pyramidal neuron damage in hippocampal DG, CA1 and CA3. Cisplatin increased nNOS and TrkB positivity in DG, CA1 and CA3 neurons compared to control. In contrast, agomelatine treatment decreased both nNOS and TrkB positive scores. These findings indicate that agomelatine reduces cisplatin-related cognitive impairment by exerting anti-inflammatory action and possibly by the modulation of the BDNF/TrkB/nNOS pathways in the hippocampus.

Preventing postoperative cognitive dysfunction using anesthetic drugs in elderly patients undergoing noncardiac surgery: a systematic review and meta-analysis

Postoperative cognitive dysfunction (POCD) is a common neurological system disorder in surgical patients. The choice of anesthetic can potentially reduce POCD. The authors performed this network meta-analysis to compare different anesthetic drugs in reducing the incidence of POCD for elderly people undergoing noncardiac surgery. We searched MEDLINE, EMBASE, the Cochrane Library, and the Web of Science for randomized controlled trials comparing the different anesthetic drugs for noncardiac surgery in elderly from inception until July, 2022. The protocol was registered on the PROSPERO database (CRD#42020183014). A total of 34 trials involving 4314 patients undergoing noncardiac surgery in elderly were included. The incidence of POCD for each anesthetic drug was placebo (27.7%), dexmedetomidine (12.9%), ketamine (15.2%), propofol (16.8%), fentanyl (23.9%), midazolam (11.3%), sufentanil (6.3%), sevoflurane (24.0%), and desflurane (28.3%). Pairwise and network meta-analysis showed dexmedetomidine was significantly reducing the incidence of POCD when compared with placebo. Network meta-analysis also suggested dexmedetomidine was significantly reducing the incidence of POCD when compared with sevoflurane. Sufentanil and dexmedetomidine ranked the first and second in reducing the incidence of POCD with the surface under the cumulative ranking curve value of 87.4 and 81.5%. Sufentanil and dexmedetomidine had the greatest possibility to reduce the incidence of POCD for elderly people undergoing noncardiac surgery.

Perioperative considerations in patients with chemotherapy-induced cognitive impairment: a narrative review

Patients with cancer may suffer from a decline in their cognitive function after various cancer therapies, including surgery, radiation, and chemotherapy, and in some cases, this decline in cognitive function persists even years after completion of treatment. Chemobrain or chemotherapy-induced cognitive impairment, a well-established clinical syndrome, has become an increasing concern as the number of successfully treated cancer patients has increased significantly. Chemotherapy-induced cognitive impairment can originate from direct neurotoxicity, neuroinflammation, and oxidative stress, resulting in alterations in grey matter volume, white matter integrity, and brain connectivity. Surgery has been associated with exacerbating the inflammatory response associated with chemotherapy and predisposes patients to develop postoperative cognitive dysfunction. As the proportion of patients living longer after these therapies increases, the magnitude of impact and growing concern of post-treatment cognitive dysfunction in these patients has also come to the fore. We review the clinical presentation, potential mechanisms, predisposing factors, diagnostic methods, neuropsychological testing, and imaging findings of chemotherapy-induced cognitive impairment and its intersection with postoperative cognitive dysfunction.

Apelin-13 activates the hippocampal BDNF/TrkB signaling pathway and suppresses neuroinflammation in male rats with cisplatin-induced cognitive dysfunction

It has been established that cisplatin causes neuronal damage and cognitive impairment. However, the mechanism is not sufficiently clear. Apelin-13 is an endogenous peptide with strong neuroprotective effects through the synthesis of neurotrophic factors and suppression of inflammation. The aim of this study was to investigate the role of brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) signaling pathway and the potential inhibitory effects of apelin-13 in the mechanism of cisplatin-induced hippocampal damage and cognitive impairment. Apelin-13 was administered to adult sprague dawley male rats at a dose of 20 nmol/kg every day for 4 weeks, cisplatin was administered at a dose of 5 mg/kg once a week for 4 weeks. The spatial and recognition memory tests of the rats were performed on the 5th week. BDNF and the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels were measured by ELISA in hippocampal homogenates. Pyramidal neuron and glial cell damage in the hippocampal CA1, CA3 and dentate gyrus (DG) were analyzed histologically. TrkB activity in the hippocampus was determined by immunohistochemical methods. Cisplatin impaired spatial and recognition memory in rats, while apelin-13 improved spatial memory but did not affect recognition memory. Cisplatin suppressed BDNF in the hippocampus while increased IL-1β and TNF-α. In contrast, apelin-13 administration increased BDNF but significantly suppressed TNF-α and IL-1B. Cisplatin caused pyramidal neuron and glial cell damage in CA1, CA3 and DG. In the cisplatin + apelin-13 group, however, pyramidal neuron and glial cell damage was less than those without apelin-13. Cisplatin increased TrkB activity in the hippocampus, which was counteracted by apelin-13. In conclusion, apelin-13 reduced the cisplatin-induced cognitive deficiency, by suppressing inflammation and stimulating the synthesis and activation of neurotrophic factors in hippocampal tissue.

Cellular mechanisms and treatments for chemobrain: insight from aging and neurodegenerative diseases

Chemotherapy is a life-saving treatment for cancer patients, but also causes long-term cognitive impairment, or "chemobrain", in survivors. However, several challenges, including imprecise diagnosis criteria, multiple confounding factors, and unclear and heterogeneous molecular mechanisms, impede effective investigation of preventions and treatments for chemobrain. With the rapid increase in the number of cancer survivors, chemobrain is an urgent but unmet clinical need. Here, we leverage the extensive knowledge in various fields of neuroscience to gain insights into the mechanisms for chemobrain. We start by outlining why the post-mitotic adult brain is particularly vulnerable to chemotherapy. Next, through drawing comparisons with normal aging, Alzheimer's disease, and traumatic brain injury, we identify universal cellular mechanisms that may underlie the cognitive deficits in chemobrain. We further identify existing neurological drugs targeting these cellular mechanisms that can be repurposed as treatments for chemobrain, some of which were already shown to be effective in animal models. Finally, we briefly describe future steps to further advance our understanding of chemobrain and facilitate the development of effective preventions and treatments.

Chemotherapy accelerates age-related development of tauopathy and results in loss of synaptic integrity and cognitive impairment

Cancer and its treatment are associated with neurotoxic side effects, including cognitive dysfunction, altered functional connectivity in the brain and structural abnormalities in white matter. There is evidence that cancer and its treatment can accelerate aging. Tau is a microtubule associated protein that contributes to microtubule stability thereby playing a key role in neuronal function. Clustering of tau is commonly observed in the aged brain and is related to cognitive decline. We hypothesized that chemotherapy-induced cognitive impairment is associated with accelerated development of tau clustering in the brain as a sign of accelerated aging. We show for the first time that treatment of adult (7-8 month-old) male C57BL/6 mice with cisplatin results in reduced cognitive function and a marked increase in the number of large endogenous tau clusters in the hippocampus when assessed 4 months later. In contrast, we detected only few small tau clusters in the hippocampus of age-matched 11-12 month-old control mice. Astrocyte GFAP expression was increased in close vicinity to the tau clusters in cisplatin-treated mice. We did not detect changes in the microglial marker Iba-1 in the brain of mice treated with cisplatin. The accelerated formation of Tau-1 clusters in cisplatin-treated mice was associated with a decrease in the levels of the post-synaptic marker PSD95 and of the presynaptic marker synaptophysin in the hippocampus. We demonstrate here for the first time that chemotherapy markedly accelerates development of signs of tauopathy and loss of synaptic integrity in the hippocampus. These findings provide a mechanistic link between chemotherapy cognitive decline and accelerated aging in cancer survivors.