Effects of lipopolysaccharide on consolidation of partial learning in the Y-maze

What animal models can tell us about long-term cognitive dysfunction following sepsis: A systematic review

Survivors of sepsis often develop long-term cognitive impairments. This review aimed at exploring the results of the behavioral tools and tests which have been used to evaluate cognitive dysfunction in different animal models of sepsis. Two independent investigators searched for sepsis- and cognition-related keywords. 6323 publications were found, of which 355 were selected based on their title, and 226 of these were chosen based on manuscript review. LPS was used to induce sepsis in 171 studies, while CLP was used in 55 studies. Inhibitory avoidance was the most widely used method for assessing aversive memory, followed by fear conditioning and continuous multi-trial inhibitory avoidance. With regard to non-aversive memory, most studies used the water maze, open-field, object recognition, Y-maze, plus maze, and radial maze tests. Both CLP and LPS models of sepsis were effective in inducing short- and long-term behavioral impairment. Our findings help elucidate the mechanisms involved in the pathophysiology of sepsis-induced cognitive changes, as well as the available methods and tests used to study this in animal models.

Post-chemotherapy cognitive impairment in hematological patients: current understanding of chemobrain in hematology

Introduction: Cognitive impairment caused by chemotherapies, a condition known as chemobrain, is a possible side effect that affects alertness, learning, memory, and concentration.Areas covered: Chemobrain has been principally investigated as a possible side-effect among cancer patients. However, numerous drugs used to treat hematological malignancies can determine the appearance of chemobrain. In this review, we have examined some commonly used drugs for the treatment of hematological malignancies which are known to have a deleterious action on cognitive functions.Numerous mechanisms have been suggested, comprising the direct neurotoxicity of chemotherapeutic drugs, oxidative stress, genetic predisposition, cytokine-provoked damage, histone modifications, immune alteration, and the action of chemotherapeutic on trophic factors and structural proteins of brain cells.Expert commentary: Cognitive dysfunction provoked by the treatment of hematological diseases is an actual challenge in clinical practice. Actually, there are no totally efficient and innocuous treatments for this syndrome. It is important that further investigations specify the existence of predictors and gravity factors to pre- and post-therapy cognitive change and identify the influence of tumor treatments on the cognitive alterations in long-term, cancer survivors. Moreover, future studies are needed to analyze the interactions between genetic risk, amyloid accumulation, intrinsic brain networks, and chemotherapy.

Cytokine-mediated blood brain barrier disruption as a conduit for cancer/chemotherapy-associated neurotoxicity and cognitive dysfunction

Neurotoxicity is a common side effect of chemotherapy treatment, with unclear molecular mechanisms. Clinical studies suggest that the most frequent neurotoxic adverse events affect memory and learning, attention, concentration, processing speeds and executive function. Emerging preclinical research points toward direct cellular toxicity and induction of neuroinflammation as key drivers of neurotoxicity and subsequent cognitive impairment. Emerging data now show detectable levels of some chemotherapeutic agents within the CNS, indicating potential disruption of blood brain barrier integrity or transport mechanisms. Blood brain barrier disruption is a key aspect of many neurocognitive disorders, particularly those characterized by a proinflammatory state. Importantly, many proinflammatory mediators able to modulate the blood brain barrier are generated by tissues and organs that are targets for chemotherapy-associated toxicities. This review therefore aims to explore the hypothesis that peripherally derived inflammatory cytokines disrupt blood brain barrier permeability, thereby increasing direct access of chemotherapeutic agents into the CNS to facilitate neuroinflammation and central neurotoxicity.

Evaluation of plant phenolic metabolites as a source of Alzheimer's drug leads

Epidemiological studies have proven an association between consumption of polyphenols and prevention of Alzheimer's disease, the most common form of dementia characterized by extracellular deposition of amyloid beta plaques. The aim of this study is pharmacological screening of the aqueous alcohol extract of Markhamia platycalyx leaves, Schotia brachypetala leaves and stalks, and piceatannol compared to aqueous alcohol extract of Camellia sinensis leaves as potential Alzheimer's disease drugs. LC-HRESI(-ve)-MSⁿ was performed to identify phenolics' profile of Schotia brachypetala stalks aqueous alcohol extract and revealed ten phenolic compounds as first report: daidzein, naringin, procyanidin isomers, procyanidin dimer gallate, quercetin 3-O-rhamnoside, quercetin 3-O-glucuronide, quercetin hexose gallic acid, quercetin hexose protocatechuic acid, and ellagic acid. Alzheimer's disease was induced by a single intraperitoneal injection of LPS. Adult male Swiss albino mice were divided into groups of 8–10 mice each receiving treatment for six days. In vivo behavioral tests (Y maze and object recognition) and in vitro estimation of amyloid beta 42 by ELISA showed significant differences between results of treated and nontreated animals.

Cognitive dysfunction among cancer survivors

Cognitive dysfunction among cancer survivors, commonly referred to as "chemobrain," has gained increased attention in the last decade. Cognitive dysfunction is now well recognized among patients with non-central nervous system cancers. It may be a consequence of the cancer, its treatment, or both. Other common problems among cancer survivors, such as insomnia, pain, depression, and fatigue, may play a role in cognitive performance. Three options to assess cognitive function at present include neuropsychologic testing, functional neuroimaging studies, and subjective evaluations, although no "gold standard" currently exists. Treatment options for survivors with cognitive problems are limited because research in this arena is in its infancy.

The effects of age on lipopolysaccharide-induced cognitive deficits and interleukin-1β expression

An acute LPS challenge immediately following day 1 of shuttlebox training triggered exacerbated central IL-1β production and disrupted memory consolidation and/or further acquisition of the task in 18-month-old mice, compared to 4-month-old controls. These deficits cannot be attributed to alterations in sickness behavior. The findings suggest that age and immune activation combine to impair learning and memory consolidation processes, and that increased central IL-1β production may play a role.

Cytokines and their relationship to the symptoms and outcome of cancer

Tumours contain immune cells and a network of pro- and anti-inflammatory cytokines, which collaborate in the development and progression of cancer. Cytokine profiles might prove to be prognostic. The systemic effects of pro-inflammatory cytokines are associated with fatigue, depression and cognitive impairment, and can affect quality of life before, during and after treatment. In people with advanced cancer, pro-inflammatory cytokines are additionally associated with anorexia and cachexia, pain, toxicity of treatment and resistance to treatment. However, physical activity might modify cytokine levels and decrease fatigue in patients with cancer, and might also improve their prognosis.

Acute systemic inflammation induces central mitochondrial damage and mnesic deficit in adult Swiss mice

The aim of this study was to investigate how the brain is affected during systemic inflammation. For this purpose, Swiss mice were challenged with a single intraperitoneal dose of lipopolysaccharide (LPS; 250microg/mouse) to mimic aspects of systemic infection. Spatial learning in Y-maze test demonstrated a differential learning profile during the training test between control and LPS-treated mice, with an alteration in the latter group. We show that systemic LPS-induced inflammation and oxidative injury as assessed by reactive oxygen species (ROS) and nitrites/nitrates (NOx) production associated with reduced glutathione (GSH) depletion, cyclooxygenase-2 (COX-2) expression, and lipid peroxidation. LPS also induced a loss in mitochondrial integrity as shown by a significant decrease in membrane potential and impairment in mitochondrial redox activity. Thus, peripheral inflammation by producing brain inflammation and oxidative injury causes mnesic deficits. It remains to determine whether such events can induce neuronal dysfunction/degeneration and, with time, lead to cholinergic deficiency, amyloid deposits and cognitive impairments as they occur in Alzheimer's disease.