Caffeine improves adult mice performance in the object recognition task and increases BDNF and TrkB independent on phospho-CREB immunocontent in the hippocampus

Association Between Caffeine Intake and Alzheimer's Disease Progression: A Systematic Review

Alzheimer's disease (AD) is a growing global health challenge, prompting increased attention on modifiable lifestyle factors that might influence disease progression. Among these, caffeine consumption has emerged as a potential protective factor, though the evidence remains complex and incompletely understood. This study aims to systematically review and evaluate the available evidence regarding the association between caffeine intake and AD progression. A comprehensive literature search was conducted across major databases including PubMed/MEDLINE, Embase, Web of Science, and Cochrane Library, covering studies from database inception through October 2024. The review included studies examining the relationship between caffeine intake and AD progression in human subjects, with quality assessment performed using the Newcastle-Ottawa Scale for observational studies and appropriate tools for other study designs. Findings indicated that higher caffeine intake (>200 mg/day) was consistently associated with a reduced risk of cognitive decline and AD progression. Plasma caffeine levels exceeding 1200 ng/ml were notably linked to a reduced risk of conversion from mild cognitive impairment (MCI) to dementia. The Mendelian randomization study suggested a protective effect of genetically predicted higher plasma caffeine levels against AD, with an odds ratio of 0.87 (95% CI: 0.76-1.00), although this did not reach statistical significance. Overall, current evidence suggests a potentially protective role of moderate caffeine consumption against AD progression, particularly in individuals with MCI. The relationship appears dose-dependent and may be influenced by genetic factors and timing of exposure. Further research, particularly well-designed prospective studies and clinical trials, is needed to establish optimal dosing strategies and identify populations most likely to benefit.

Coffee and amyotrophic lateral sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder characterized by progressive loss of motor neurons. The effective treatments for ALS remain elusive, necessitating exploration into novel preventive strategies. ALS pathogenesis is triggered by oxidative stress which results in neuroinflammation, exicitotoxicity and neuronal cell death. Nutritional mechanism for halting progression of neurodegeneration is through dietary compounds with antioxidants, anti-inflammatory or neuromodulating activity. Coffee is a widely consumed beverage made up of polyphenols, caffeine and other compounds with possible antioxidants and neuro-protective roles. It is important to say that various epidemiological studies have documented association between coffee intake and ALS. This chapter is aimed to present a comprehensive review of existing literature on coffee consumption and ALS, involving epidemiological studies, preclinical research, and its mechanism of actions in animal model of ALS. It highlights key findings regarding the potential neuroprotective properties of coffee constituents such as caffeine, polyphenols, and other bioactive compounds. Furthermore, it discusses possible pathways through which coffee may modulate ALS pathogenesis, including suppressing oxidative stress and neuroinflammation while boosting adenosine function via the adenosine receptor two on the motor neuron cells membrane in the spinal cord to enhance motor function via the corticospinal tract. Overall, this chapter underscores the significance of further research to unravel the specific mechanisms by which coffee exerts its neuroprotective effects in ALS, with the ultimate goal of identifying dietary strategies for ALS prevention and management.

Current therapeutic targets and multifaceted physiological impacts of caffeine

Caffeine, which shares consubstantial structural similarity with purine adenosine, has been demonstrated as a nonselective adenosine receptor antagonist for eliciting most of the biological functions at physiologically relevant dosages. Accumulating evidence supports caffeine's beneficial effects against different disorders, such as total cardiovascular diseases and type 2 diabetes. Conversely, paradoxical effects are also linked to caffeine ingestion in humans including hypertension-hypotension and tachycardia-bradycardia. These observations suggest the association of caffeine action with its ingested concentration and/or concurrent interaction with preferential molecular targets to direct explicit events in the human body. Thus, a coherent analysis of the functional targets of caffeine, relevant to normal physiology, and disease pathophysiology, is required to understand the pharmacology of caffeine. This review provides a broad overview of the experimentally validated targets of caffeine, particularly those of therapeutic interest, and the impacts of caffeine on organ-specific physiology and pathophysiology. Overall, the available empirical and epidemiological evidence supports the dose-dependent functional activities of caffeine and advocates for further studies to get insights into the caffeine-induced changes under specific conditions, such as asthma, DNA repair, and cancer, in view of its therapeutic applications.

Spatial Regulation Control of Oxygen Metabolic Consumption in Mouse Brain

The mammalian brain relies on significant oxygen metabolic consumption to fulfill energy supply, brain function, and neural activity. In this study, in vivo electrochemistry is combined with physiological and ethological analyses to explore oxygen metabolic consumption in an area of the mouse brain that includes parts of the primary somatosensory cortex, primary motor cortex, hippocampus, and striatum. The oxygen levels at different locations of this boundary section are spatially resolved by measuring the electrical current in vivo using ingeniously designed anti-biofouling carbon fiber microelectrodes. The characteristics of the current signals are further interpreted by simultaneously recording the physiological responses of the mice. Additionally, ethological tests are performed to validate the correlation between oxygen levels and mouse behavior. It is found that high-dose caffeine injection can evoke spatial variability in oxygen metabolic consumption between the four neighboring brain regions. It is proposed that the oxygen metabolic consumption in different brain regions is not independent of each other but is subject to spatial regulation control following the rules of "rank of brain region" and "relative distance." Furthermore, as revealed by in vivo wireless electrochemistry and ethological analysis, mice are at risk of neuronal damage from long-term intake of high-dose caffeine.

Electroacupuncture stimulation of HT7 alleviates sleep disruption following acute caffeine exposure by regulating BDNF-mediated endoplasmic reticulum stress in the rat medial septum

Acupuncture stimulation can protect the brain against caffeine-induced sleep disruption. This study investigated whether electroacupuncture stimulation acupuncture point HT7 alleviates sleep disruption by regulating mBDNF and ER stress in the medial septum. Acute exposure to caffeine (15 mg/kg, i.p.) increased the wake time and decreased REM sleep, which HT7 stimulation alleviated. HT7 stimulation ameliorated the acute caffeine exposure-induced increase in the expression of BiP, an endoplasmic reticulum stress response protein, in the rat medial septum. Interestingly, HT7 stimulation induced the expression of mBDNF and pTrkB in the medial septum. The next experiment investigated whether TrkB phosphorylated by HT7 stimulation induced BiP expression in the rat medial septum. Before electroacupuncture stimulation at HT7, ANA-12 was administered to caffeine-treated rats. In rats administered ANA-12 in the medial septum, HT7 stimulation did not reduce BiP expression. These findings suggest that HT7 stimulation improves wake time and REM sleep dysfunction by regulating the BDNF-mediated endoplasmic reticulum stress response in the medial septum. These results indicate that the alleviation of endoplasmic reticulum stress in the medial septum by HT7 stimulation and the subsequent amelioration of insomnia may depend on phosphorylated TrkB activation.

Oxytocin treatment improves dexamethasone‐induced depression‐like symptoms associated with enhancement of hippocampal CREB‐BDNF signaling in female mice

Aims

Chronic stress and glucocorticoid exposure are risk factors for depression. Oxytocin (OT) has been shown to have antistress and antidepressant‐like effects in male rodents. However, depression is twice as common in women than in men, and it remains unclear whether OT exerts antidepressant‐like effects in women with depression. Therefore, in this study, we investigated the therapeutic effect of chronic OT administration in a female mouse model of dexamethasone (DEX)‐induced depression.

Methods

Female C57BL/6J mice were administered saline (vehicle, s.c.), DEX (s.c.), or OT (i.p.) + DEX (s.c.) daily for 8 weeks, and then assessed for anxiety‐ and depression‐like behaviors. We also examined the hippocampal levels of phosphorylated cAMP response element‐binding protein (p‐CREB) and brain‐derived neurotrophic factor (BDNF), which are important mediators of the response to antidepressants.

Results

Simultaneous OT treatment blocked the adverse effects of DEX on emotional behaviors. Furthermore, it upregulated p‐CREB and BDNF in the hippocampus.

Conclusion

OT may exert antidepressant‐like effects by activating hippocampal CREB‐BDNF signaling in a female mouse model of depression.

Adenosine A2A Receptor Blockade Ameliorates Mania Like Symptoms in Rats: Signaling to PKC-α and Akt/GSK-3β/β-Catenin

Adenosinergic system dysfunction is implicated in the pathophysiology of multiple neuropsychiatric disorders including mania and bipolar diseases. The established synergistic interaction between A_2A and D₂ receptors in the prefrontal cortex could highlight the idea of A_2A receptor antagonism as a possible anti-manic strategy. Hence, the present study was performed to examine the effect of a selective adenosine A_2A receptor blocker (SCH58261) on methylphenidate-induced mania-like behavior while investigating the underlying mechanisms. Rats were injected with methylphenidate (5 mg/kg/day, i.p.) for 3 weeks with or without administration of either SCH58261 (0.01 mg/kg/day, i.p.) or lithium (150 mg/kg/day, i.p.) starting from day 9. In the diseased rats, adenosine A_2AR antagonism reduced locomotor hyperactivity and risk-taking behavior along with decreased dopamine and glutamate levels. Meanwhile, SCH58261 restored NMDA receptor function, suppressed PKC-α expression, down-regulated β-Arrestin-2, up-regulated pS473-Akt and pS9-GSK-3β. Further, SCH58261 promoted synaptic plasticity markers through increasing BDNF levels along with down-regulating GAP-43 and SNAP-25. The A_2A antagonist also reduced NF-κBp65 and TNF-α together with elevating IL-27 level giving an anti-inflammatory effect. In conclusion, suppression of PKC-α and modulation of Akt/GSK-3β/β-catenin axis through A_2AR inhibition, could introduce adenosine A_2AR as a possible therapeutic target for treatment of mania-like behavior. This notion is supported by the ability of the A_2AR antagonist (SCH58261) to produce comparable results to those observed with the standard anti-manic drug (Lithium).

Behavioral, genetic and biochemical changes in the brain of the offspring of female mice treated with caffeine during pregnancy and lactation

The intrauterine environment is a critical location for exposure to exogenous and endogenous factors that trigger metabolic changes through fetal programming. Among the external factors, chemical compounds stand out, which include caffeine, since its consumption is common among women, including during pregnancy. Thereby, the aim of the present study was to evaluate the behavioral, genetic, and biochemical parameters in the offspring of female mice treated with caffeine during pregnancy and lactation. Swiss female mice (60 days old) received tap water or caffeine at 0.3 or 1.0 mg/mL during copulation (7 days), pregnancy (21 days) and lactation (21 days). After the end of the lactation period, the offspring were divided into groups (water, caffeine 0.3 or 1.0 mg/mL) with 20 animals (10 animals aged 30 days and 10 animals aged 60 days per group per sex). Initially, the offspring were submitted to behavioral tasks and then euthanized for genetic and biochemical analysis in the brain (cortex, striatum, and hippocampus). Behavioral changes in memory, depression, and anxiety were observed in the offspring: 30-day-old female offspring at 1.0 mg /mL dose presented anxiogenic behavior and male offspring the 0.3 mg/mL dose at 30 days of age did not alter long-term memory. Furthermore, an increase in DNA damage and oxidative stress in the brain were observed in the offspring of both sexes. Furthermore, there were changes in Ape-1, BAX, and Bcl-2 in the female offspring hippocampus at 30 days of life. Thus, with this study, we can suggest genotoxicity, oxidative stress, and behavioral changes caused by caffeine during pregnancy and lactation in the offspring that were not treated directly, but received through their mothers; thus, it is important to raise awareness regarding caffeine consumption among pregnant and lactating females.

Chronic caffeine consumption improves the acute REM sleep deprivation-induced spatial memory impairment while altering NMDA receptor subunit expression in male rats

Caffeine is a psychostimulant substance that is mostly used to prevent fatigue, increase alertness, and ameliorate sleep loss situations. In this study, we aimed to investigate the effect of chronic caffeine consumption on learning and memory functions and related genes in REM (rapid-eye-movement) sleep-deprived rats. During the neonatal period [postnatal day (PND) 28] Wistar albino male rats (n=32) were randomly assigned into four groups: control (C), caffeine application (Cf), acute REM sleep-deprivation (RD), and caffeine application+acute RD (Cf+RD). The 48 hours of RD was executed when caffeine administration was completed. The learning and memory performance was evaluated by the Morris Water Maze Test (MWMT). Following this, the rats were decapitated to isolate hippocampus tissues. In MWMT, time spent in the targeted quadrant decreased significantly in the RD group compared to the C and Cf+RD group. NR2A expression level increased in the RD group compared to C, Cf, and Cf+RD groups (p<0.05). NR2B expression level increased in RD and Cf +RD groups compared to C and Cf groups (p<0.05). BDNF and c-Fos expression levels did not differ significantly between the groups. RD impaired hippocampal spatial memory performance in the MWMT test. Our results indicated that chronic caffeine consumption has a therapeutic effect on spatial memory deterioration impairment caused by RD. Furthermore, it seems that the effect of caffeine RD on the hippocampus may be mediated by NR2A.

Post-learning caffeine administration improves 'what-when' and 'what-where' components of episodic-like memory in rats

Episodic-like memory (ELM) consists in the capacity of nonhuman animals to remember 'where' and 'when' a specific episode occurred ('what'). Previous studies have showed that Wistar rats can form an ELM, but not after a 24 h retention delay. On the other hand, it has been demonstrated that caffeine can improve episodic memory consolidation in humans. Therefore, we verified whether acute post-sample caffeine administration could improve ELM consolidation in Wistar rats, as well if it could be related to neurochemical changes in the prefrontal cortex and hippocampus - regions related to episodic-like memory processing. 46 Male Wistar Rats, approximately 3 months-old, were divided into four groups as follows: untreated (n = 11), saline (n = 11), caffeine 10 mg ∕kg i.p (n = 12); caffeine 15 mg∕kgi.p (n = 12) and tested in WWWhen/ELM task. The animals treated with caffeine in different dosages (10 mg/kg and 15 mg/kg) discriminated temporally and spatially the objects, respectively. These groups also showed a dopamine renewal rate in the hippocampus, suggesting that there was an increase in the turnover compared with the groups with no caffeine administration. We can conclude that caffeine leads to an improvement in the consolidation of the temporal ('what-when') and spatial ('what-where') aspects of episodic-like memory.

Caffeine Protects Against Retinal Inflammation

Caffeine, one of the most consumed central nervous system (CNS) stimulants, is an antagonist of A₁ and A_2A adenosine receptors. In this study, we investigated the potential protective effects of this methylxanthine in the retinal tissue. We tested caffeine by using in vitro and in vivo paradigms of retinal inflammation. Human retinal pigment epithelial cells (ARPE-19) were exposed to lipopolysaccharide (LPS) with or without caffeine. This latter was able to reduce the inflammatory response in ARPE-19 cells exposed to LPS, attenuating the release of IL-1β, IL-6, and TNF-α and the nuclear translocation of p-NFκB. Additionally, caffeine treatment restored the integrity of the ARPE-19 monolayer assessed by transepithelial electrical resistance (TEER) and the sodium fluorescein permeability test. Finally, the ischemia reperfusion (I/R) injury model was used in C57BL/6J mice to induce retinal inflammation and investigate the effects of caffeine treatment. Mouse eyes were treated topically with caffeine, and a pattern electroretinogram (PERG) was used to assess the retinal ganglion cell (RGC) function; furthermore, we evaluated the levels of IL-6 and BDNF in the retina. Retinal BDNF dropped significantly (p < 0.05) in the I/R group compared to the control group (normal mice); on the contrary, caffeine treatment maintained physiological levels of BDNF in the retina of I/R eyes. Caffeine was also able to reduce IL-6 mRNA levels in the retina of I/R eyes. In conclusion, these findings suggest that caffeine is a good candidate to counteract inflammation in retinal diseases.

Experimental study of pre- and postnatal caffeine exposure and its observable effects on selected neurotransmitters and behavioural attributes at puberty : Caffeine exposure and its observable effects on selected neurotranmitters and behaviour

Caffeine is globally consumed as a stimulant in beverages. It is also ingested in purified forms as power and tablets. Concerns have been raised about the potential consequences of intrauterine and early life caffeine exposure on brain health. This study modeled caffeine exposure during pregnancy and early postanal life until puberty, and the potential consequences. Caffeine powder was dissolved in distilled water. Thirty-two (n = 32) pregnant mice (Mus musculus) (dams) were divided into four groups- A, B, C and D. Group A animals served as a control, receiving placebo. Caffeine doses in mg/kg body weight were administered as follows: Group B, 10 mg/kg; Group C, 50 mg/kg; Group D, 120 mg/kg. Prenatal caffeine exposure [phase I] lasted throughout pregnancy. Half the number of offspring (pups) were sacrificed at birth; the rest were recruited into phase II and the experiment continued till day 35, marking puberty. Brain samples were processed following sacrifice. γ-aminobutyric acid (GABA), acetylcholine (ACh), and serotonin (5Ht) neurotransmitters were assayed in homogenates to evaluate functional neurochemistry. Anxiety and memory as neurobehavioural attributes were observed using the elevated plus and Barnes' mazes respectively. Continuous caffeine exposure produced positive effects on short and long-term memory parameters; the pattern interestingly was irregular and appeared more effective with the lowest experimental dose. Anxiety test results showed no attributable significant aberrations. Caffeine exposure persistently altered the neurochemistry of selected neurotransmitters including ACh and 5Ht, including when exposure lasted only during pregnancy. ACh significantly increased in group B^C+ to 0.3475μgg-¹ relative to control's 0.2508μgg-¹; pre-and continuous postnatal exposure in Group B increased 5Ht to 0.2203 μgg-¹ and 0.2213 μgg-¹ respectively relative to control's 0.1863 μgg-¹. From the current investigation, caffeine exposure in pregnancy had persistent effects on brain functional attributes including neurotransmitters activities, memory and anxiety. Caffeine in moderate doses affected memory positively but produced negative effects at the higher dosage including increased anxiety tendencies.

Serum proBDNF Is Associated With Changes in the Ketone Body β-Hydroxybutyrate and Shows Superior Repeatability Over Mature BDNF: Secondary Outcomes From a Cross-Over Trial in Healthy Older Adults

Background: β-hydroxybutyrate (BHB) can upregulate brain-derived neurotrophic factor (BDNF) in mice, but little is known about the associations between BHB and BDNF in humans. The primary aim here was to investigate whether ketosis (i.e., raised BHB levels), induced by a ketogenic supplement, influences serum levels of mature BDNF (mBDNF) and its precursor proBDNF in healthy older adults. A secondary aim was to determine the intra-individual stability (repeatability) of those biomarkers, measured as intra-class correlation coefficients (ICC).

Method: Three of the arms in a 6-arm randomized cross-over trial were used for the current sub-study. Fifteen healthy volunteers, 65–75 y, 53% women, were tested once a week. Test oils, mixed in coffee and cream, were ingested after a 12-h fast. Labeled by their level of ketosis, the arms provided: sunflower oil (lowK); coconut oil (midK); caprylic acid + coconut oil (highK). Repeated blood samples were collected for 4 h after ingestion. Serum BDNF levels were analyzed for changes from baseline to 1, 2 and 4 h to compare the arms. Individual associations between BHB and BDNF were analyzed cross-sectionally and for a delayed response (changes in BHB 0–2 h to changes in BDNF at 0–4 h). ICC estimates were calculated from baseline levels from the three study days.

Results: proBDNF increased more in highK vs. lowK between 0 and 4 h (z-score: β = 0.25, 95% CI 0.07–0.44; p = 0.007). Individual change in BHB 0–2 h, predicted change in proBDNF 0–4 h, (β = 0.40, CI 0.12–0.67; p = 0.006). Change in mBDNF was lower in highK vs. lowK at 0–2 h (β = −0.88, CI −1.37 to −0.40; p < 0.001) and cumulatively 0–4 h (β = −1.01, CI −1.75 to −0.27; p = 0.01), but this could not be predicted by BHB levels. ICC was 0.96 (95% CI 0.92–0.99) for proBDNF, and 0.72 (CI 0.47–0.89) for mBDNF.

Conclusions: The findings support a link between changes in peripheral BHB and proBDNF in healthy older adults. For mBDNF, changes differed between arms but independent to BHB levels. Replication is warranted due to the small sample. Excellent repeatability encourages future investigations on proBDNF as a predictor of brain health.

Clinical Trial Registration:ClinicalTrials.gov, NCT03904433.

Bioactive Compounds and Traditional Herbal Medicine: Promising Approaches for the Treatment of Dementia

Dementia is a term that encompasses a group of clinical symptoms affecting memory, thinking and social abilities, characterized by progressive impairment of memory performance and cognitive functions. There are several factors involved in the pathogenesis and progression of dementia, such as old age, brain ischemia, toxin exposure, and oxidative stress. There are extensive similarities between dementia and Alzheimer's disease (AD) either in clinical manifestations or experimental animal models. AD is the most dominant form of dementia, characterized by the accumulation of beta-amyloid protein and cholinergic neurotransmission deficits in the brain. Currently available medications for the treatment of dementia, such as choline esterase inhibitors, N-methyl-D-aspartate (NMDA) antagonists (memantine), have short-term efficacy and only relieve symptoms rather than targeting the main underlying pathogenesis. Several animal studies and clinical trials are being conducted to provide a rational approach to these medicinal plants in the prevention or treatment of memory deficits. This review highlights the potential effects of medicinal plants and their derived lead molecules, and explains the related mechanisms and effects reviewed from published literature as major thrust aspects and hopeful strategies in the prevention or treatment of dementia.

New insights into the effects of caffeine on adult hippocampal neurogenesis in stressed mice: Inhibition of CORT-induced microglia activation

Chronic stress-evoked depression has been implied to associate with the decline of adult hippocampal neurogenesis. Caffeine has been known to combat stress-evoked depression. Herein, we aim to investigate whether the protective effect of caffeine on depression is related with improving adult hippocampus neurogenesis and explore the mechanisms. Mouse chronic water immersion restraint stress (CWIRS) model, corticosterone (CORT)-established cell stress model, a coculture system containing CORT-treated BV-2 cells and hippocampal neural stem cells (NSCs) were utilized. Results showed that CWIRS caused obvious depressive-like disorders, abnormal 5-HT signaling, and elevated-plasma CORT levels. Notably, microglia activation-evoked brain inflammation and inhibited neurogenesis were also observed in the hippocampus of stressed mice. In comparison, intragastric administration of caffeine (10 and 20 mg/kg, 28 days) significantly reverted CWIRS-induced depressive behaviors, neurogenesis recession and microglia activation in the hippocampus. Further evidences from both in vivo and in vitro mechanistic experiments demonstrated that caffeine treatment significantly suppressed microglia activation via the A2AR/MEK/ERK/NF-κB signaling pathway. The results suggested that CORT-induced microglia activation contributes to stress-mediated neurogenesis recession. The antidepression effect of caffeine was associated with unlocking microglia activation-induced neurogenesis inhibition.

Caffeine prevents neurodegeneration and behavioral alterations in a mice model of agitated depression

Longitudinal and some experimental studies have showed the potential of caffeine to counteract some depressive behaviors and synaptic dysfunctions. In this study, we investigated the potential of caffeine in preventing behavioral outcomes, neurodegeneration and synaptic proteins alterations in a mice model of agitated depression by bilateral olfactory bulbectomy (OB). For this purpose, bulbectomized mice received caffeine (0.3 g/L and 1.0 g/L, drinking water), during the active cycle, for seven weeks (two before the surgery and throughout five weeks after OB). Caffeine prevented OB-induced hyperactivity and recognition memory impairment and rescue self care and motivational behavior. In the frontal cortex, bulbectomized mice presented increase in the adenosine A₁ receptors (A₁R) and GFAP, while adenosine A_2A receptors (A_2AR) increased in the hippocampus and striatum and SNAP-25 was decreased in frontal cortex and striatum. Caffeine increased A₁R in the striatum of bulbectomized mice and in SHAM-water group caffeine increased A_2AR in the striatum and decreased SNAP-25 in the frontal cortex. Astrogliosis observed in the polymorphic layer of the dentate gyrus of OB mice was prevented by caffeine as well as the neurodegeneration in the striatum and piriform cortex. Based on these behavioral and neurochemical evidences, caffeine confirms its efficacy in preventing neurodegeneration associated with memory impairment and may be considered as a promising therapeutic tool in the prophylaxis and/or treatment of depression.

A New Hypothesis on Anxiety, Sleep Insufficiency, and Viral Infections; Reciprocal Links to Consider in Today's "World vs. COVID-19" Endeavors

In today's ever-growing concerns about the coronavirus disease (COVID-19) pandemic, many experience sleep insufficiencies, such as difficulty falling or staying asleep, sleep-related behavioral symptoms, and out-of-phase circadian rhythmicity despite the lack of history of earlier such symptoms. Meanwhile, the disruption in sleep bioparameters is experienced more in people with a history of sleep disorders. The behavioral sleep disorders in the current situations are prevalent given the today's amount of anxiety everyone is feeling about COVID-19. On the other hand, evidences indicated that the cross-link between impaired sleep efficiency and disrupted innate immunity makes people susceptible to viral infections. The present brief review highlights the links between psychosocial stress, sleep insufficiency, and susceptibility to viral infections in relevance to COVID-19 situation. The stress management measures, including addressing sleep-related disorders and sleep hygiene, will have a notable impact by harnessing immune response and thus reducing the susceptibility to viral infections.

Negative Mood Is Associated with Diet and Dietary Antioxidants in University Students During the Menstrual Cycle: A Cross-Sectional Study from Guangzhou, China

Postpubescent females may have negative mood or premenstrual syndrome during the menstrual cycle; with the emotional and physical symptoms interfering with their quality of life. Little is known about the relationship of dietary behaviors and dietary antioxidant intake with negative mood or premenstrual syndrome in university students in China; so we explored the relationship between negative mood and dietary behavior in female university students during the three menstrual cycle phases. Random sampling was used to enroll 88 individuals from a university in Guangzhou; China in the study. Data were collected using self-administered questionnaires. Descriptive statistics and multiple logistic regression analyses were performed. During the menstrual phase, tea, black coffee and carbonated beverage intake was higher in the group with a high negative affect scale score than in the low score group (p < 0.05). Likewise; during the premenstrual phase, fresh fruit (banana and red Chinese dates) intake was higher in the group with a high negative affect scale score than in the low-score group (p < 0.05). The logistic regression analysis results showed that negative mood was positively associated with tea, coffee, and carbonated beverage intake during the menstrual phase (β = 0.21, p = 0.0453, odds ratio = 1.23), and negative mood was positively associated with banana and red Chinese dates intake during the premenstrual phase (β = 0.59, p = 0.0172, odds ratio = 1.81). Our results suggest that negative mood may be associated with diet and specific food in university postpubescent females.

Caffeine and adenosine A2A receptors rescue neuronal development in vitro of frontal cortical neurons in a rat model of attention deficit and hyperactivity disorder

Although some studies have supported the effects of caffeine for treatment of Attention deficit and hyperactivity disorder (ADHD), there were no evidences about its effects at the neuronal level. In this study, we sought to find morphological alterations during in vitro development of frontal cortical neurons from Spontaneoulsy hypertensive rats (SHR, an ADHD rat model) and Wistar-Kyoto rats (WKY, control strain). Further, we investigated the effects of caffeine and adenosine A₁ and A_2A receptors (A₁R and A_2AR) signaling. Cultured cortical neurons from WKY and SHR were analyzed by immunostaining of microtubule-associated protein 2 (MAP-2) and tau protein after treatment with either caffeine, or A₁R and A_2AR agonists or antagonists. Besides, the involvement of PI3K and not PKA signaling was also assessed. Neurons from ADHD model displayed less neurite branching, shorter maximal neurite length and decreased axonal outgrowth. While caffeine recovered neurite branching and elongation from ADHD neurons via both PKA and PI3K signaling, A_2AR agonist (CGS 21680) promoted more neurite branching via PKA signaling. The selective A_2AR antagonist (SCH 58261) was efficient in recovering axonal outgrowth from ADHD neurons through PI3K and not PKA signaling. For the first time, frontal cortical neurons were isolated from ADHD model and they presented disturbances in the differentiation and outgrowth. By showing that caffeine and A_2AR may act at neuronal level rescuing ADHD neurons outgrowth, our findings strengthen the potential of caffeine and A_2AR receptors as an adjuvant for ADHD treatment.

Protective Effects of the Caffeine Against Neurodegenerative Diseases

Background:

Recent studies and increased interest of the scientific community helped to clarify the neurological health property of caffeine, one of the pharmacologically active substances most consumed in the world.

Methods:

This article is a review search to provide an overview on the current state of understanding neurobiochemical impact of caffeine, focusing on the ability of the drug to effectively counteract several neurodegenerative disorders such as Alzheimer’s, Parkinson’s, Huntington’s diseases, Multiple sclerosis and Amyotrophic lateral sclerosis.

Results:

Data collection shown in this review provide a significant therapeutic and prophylactic potentiality of caffeine which acts on human brain through several pathways because of its antioxidant activity combined with multiple molecular targets. However, the need to adjust the CF dosage to individuals, because some people are more sensitive to drugs than others, may constituted a limit to the CF effectiveness.

Conclusion:

What emerges from the complex of clinical and epidemiological studies is a significant CF potential impact against all neurological disorders. Although, further studies are needed to fully elucidate the several mechanisms of drug action which in part are still elusive.

Reviewing Biochemical Implications of Normal and Mutated Huntingtin in Huntington's Disease

Huntingtin (Htt) is a multi-function protein of the brain. Normal Htt shows a common alpha-helical structure but conformational changes in the form with beta strands are the principal cause of Huntington's disease. Huntington's disease is a genetic neurological disorder caused by a repeated expansion of the CAG trinucleotide, causing instability in the N-terminal of the gene coding for the Huntingtin protein. The mutation leads to the abnormal expansion of the production of the polyglutamine tract (polyQ) resulting in the form of an unstable Huntingtin protein commonly referred to as mutant Huntingtin. Mutant Huntingtin is the cause of the complex neurological metabolic alteration of Huntington's disease, resulting in both the loss of all the functions of normal Huntingtin and the genesis of abnormal interactions due to the presence of this mutation. One of the problems arising from the misfolded Huntingtin is the increase in oxidative stress, which is common in many neurological diseases such as Alzheimer's, Parkinson's, Amyotrophic Lateral Sclerosis and Creutzfeldt-Jakob disease. In the last few years, the use of antioxidants had a strong incentive to find valid therapies for defence against neurodegenerations. Although further studies are needed, the use of antioxidant mixtures to counteract neuronal damages seems promising.

Pulmonary rehabilitation and BDNF levels in patients with chronic obstructive pulmonary disease: A pilot study

BACKGROUND

COPD physiopathology involves multiple pathways and evidence indicates that brain-derived neurotrophic factor (BDNF) is an important biomarker associated with parameters of COPD severity. This study aimed to analyze the time course of the effects of a pulmonary rehabilitation program (PRP) on BDNF levels and on functional status in COPD patients.

METHODS

Patients were enrolled in a 24-session PRP. Exercise capacity, dyspnea, health-related quality of life, and the BODE index were assessed at baseline and after the PRP. BDNF plasma levels were measured at baseline (immediately before the 1^st session), after the 1^st session, and before and after the 24^th session.

RESULTS

Sixteen patients were included. A reduction in BDNF levels was observed after the 1^st session and an increase was observed between the end of the 1^st session and the beginning of the 24^th session. The PRP promoted an improvement in exercise capacity and health-related quality of life and a reduction in dyspnea and the BODE index.

CONCLUSION

Exercise acutely reduced BDNF levels, an effect that was nullified by the overall intervention.

Sucrose or sucrose and caffeine differentially impact memory and anxiety-like behaviours, and alter hippocampal parvalbumin and doublecortin

Caffeinated sugar-sweetened "energy" drinks are a subset of soft drinks that are popular among young people worldwide. High sucrose diets impair cognition and alter aspects of emotional behaviour in rats, however, little is known about sucrose combined with caffeine. Rats were allocated to 2 h/day 10% sucrose (Suc), 10% sucrose plus 0.04% caffeine (CafSuc) or control (water) conditions. The addition of caffeine to sucrose appeared to increase the rewarding aspect of sucrose, as the CafSuc group consumed more solution than the Suc group. After 14 days of intermittent Suc or CafSuc access, anxiety was assessed in the elevated plus maze (EPM) prior to their daily solution access, whereby CafSuc and Suc rats spent more time in the closed arms, indicative of increased anxiety. Following daily solution access, CafSuc, but not Suc, rats showed reduced anxiety-like behaviour in the open-field. Control and CafSuc rats displayed intact place and long-term object memory, while Suc showed impaired memory performance. Sucrose reduced parvalbumin immunoreactivity in the hippocampus, but no differences were observed between Control and CafSuc conditions. Parvalbumin reactivity in the basolateral amygdala did not differ between conditions. Reduced doublecortin immunoreactivity in the dentate gyrus relative to controls was seen in the CafSuc, but not Suc, treatment conditions. These findings indicate that the addition of caffeine to sucrose attenuated cognitive deficits. However, the addition of caffeine to sucrose evoked anxiety-like responses under certain testing conditions, suggesting that frequent consumption of caffeinated energy drinks may promote emotional alterations and brain changes compared to standard soft drinks.

Serum brain-derived neurotrophic factor predicting reduction in pulse pressure after a one-hour rest in nurses working night shifts

Night shift work is associated with cardiovascular disease and central nervous system disorders in female nurses. Brain-derived neurotrophic factor (BDNF) exerts protective effects on neural and endothelial functions. This study examined the association between serum BDNF levels and pulse pressure after rest in female nurses working night shifts. In this study, blood samples were collected for BDNF measurement after a night shift when nurses had been working night shifts for three continuous weeks. Blood pressure was assessed before and after a one-hour morning rest within a week of resuming the night shift after one month without any night shift work. The pulse pressure of nurses (n = 48, age 29 ± 5 years) was significantly reduced (from 43 ± 7 to 41 ± 6 mmHg, P = 0.003) after rest, and serum BDNF were significantly and inversely correlated with pulse pressure changes (r = −0.435, P = 0.002). Higher serum BDNF was an independent factor for greater reduction in pulse pressure (95%CI = −0.609 ‒ −0.174, P = 0.001). Using a receiver operating characteristic curve analysis, serum BDNF >20.6 ng/mL predicted a pulse pressure reduction after a one-hour rest (sensitivity 66.7%, specificity 77.8%). In conclusion, higher serum BDNF predicted greater recovery of pulse pressure after a one-hour rest in female nurses after night shift work.

Sex differences in the effects of pre- and postnatal caffeine exposure on behavior and synaptic proteins in pubescent rats

Few studies have addressed the effects of caffeine in the puberty and/or adolescence in a sex dependent manner. Considering that caffeine intake has increased in this population, we investigated the behavioral and synaptic proteins changes in pubescent male and female rats after maternal consumption of caffeine. Adult female Wistar rats started to receive water or caffeine (0.1 and 0.3g/L in drinking water; low and moderate dose, respectively) during the active cycle at weekdays, two weeks before mating. The treatment lasted up to weaning and the offspring received caffeine until the onset of puberty (30-34days old). Behavioral tasks were performed to evaluate locomotor activity (open field task), anxious-like behavior (elevated plus maze task) and recognition memory (object recognition task) and synaptic proteins levels (proBDNF, BDNF, GFAP and SNAP-25) were verified in the hippocampus and cerebral cortex. While hyperlocomotion was observed in both sexes after caffeine treatment, anxiety-related behavior was attenuated by caffeine (0.3g/L) only in females. While moderate caffeine worsened recognition memory in females, an improvement in the long-term memory was observed in male rats for both doses. Coincident with memory improvement in males, caffeine increased pro- and BDNF in the hippocampus and cortex. Females presented increased proBDNF levels in both brain regions, with no effects of caffeine. While GFAP was not altered, moderate caffeine intake increased SNAP-25 in the cortex of female rats. Our findings revealed that caffeine promoted cognitive benefits in males associated with increased BDNF levels, while females showed less anxiety. Our findings revealed that caffeine promotes distinct behavioral outcomes and alterations in synaptic proteins during brain development in a sex dependent manner.

Botanicals as Modulators of Neuroplasticity: Focus on BDNF

The involvement of brain-derived neurotrophic factor (BDNF) in different central nervous system (CNS) diseases suggests that this neurotrophin may represent an interesting and reliable therapeutic target. Accordingly, the search for new compounds, also from natural sources, able to modulate BDNF has been increasingly explored. The present review considers the literature on the effects of botanicals on BDNF. Botanicals considered were Bacopa monnieri (L.) Pennell, Coffea arabica L., Crocus sativus L., Eleutherococcus senticosus Maxim., Camellia sinensis (L.) Kuntze (green tea), Ginkgo biloba L., Hypericum perforatum L., Olea europaea L. (olive oil), Panax ginseng C.A. Meyer, Rhodiola rosea L., Salvia miltiorrhiza Bunge, Vitis vinifera L., Withania somnifera (L.) Dunal, and Perilla frutescens (L.) Britton. The effect of the active principles responsible for the efficacy of the extracts is reviewed and discussed as well. The high number of articles published (more than one hundred manuscripts for 14 botanicals) supports the growing interest in the use of natural products as BDNF modulators. The studies reported strengthen the hypothesis that botanicals may be considered useful modulators of BDNF in CNS diseases, without high side effects. Further clinical studies are mandatory to confirm botanicals as preventive agents or as useful adjuvant to the pharmacological treatment.

Caffeine-mediated BDNF release regulates long-term synaptic plasticity through activation of IRS2 signaling

Caffeine has cognitive‐enhancing properties with effects on learning and memory, concentration, arousal and mood. These effects imply changes at circuital and synaptic level, but the mechanism by which caffeine modifies synaptic plasticity remains elusive. Here we report that caffeine, at concentrations representing moderate to high levels of consumption in humans, induces an NMDA receptor‐independent form of LTP (_CAFLTP) in the CA1 region of the hippocampus by promoting calcium‐dependent secretion of BDNF, which subsequently activates TrkB‐mediated signaling required for the expression of _CAFLTP. Our data include the novel observation that insulin receptor substrate 2 (IRS2) is phosphorylated during induction of _CAFLTP, a process that requires cytosolic free Ca²⁺. Consistent with the involvement of IRS2 signals in caffeine‐mediated synaptic plasticity, phosphorylation of Akt (Ser473) in response to LTP induction is defective in Irs2^−/− mice, demonstrating that these plasticity changes are associated with downstream targets of the phosphoinositide 3‐kinase (PI3K) pathway. These findings indicate that TrkB‐IRS2 signals are essential for activation of PI3K during the induction of LTP by caffeine.

Cognitive impairment and gene expression alterations in a rodent model of binge eating disorder

Binge eating disorder (BED) is defined as recurrent, distressing over-consumption of palatable food (PF) in a short time period. Clinical studies suggest that individuals with BED may have impairments in cognitive processes, executive functioning, impulse control, and decision-making, which may play a role in sustaining binge eating behavior. These clinical reports, however, are limited and often conflicting. In this study, we used a limited access rat model of binge-like behavior in order to further explore the effects of binge eating on cognition. In binge eating prone (BEP) rats, we found novel object recognition (NOR) as well as Barnes maze reversal learning (BM-RL) deficits. Aberrant gene expression of brain derived neurotrophic factor (Bdnf) and tropomyosin receptor kinase B (TrkB) in the hippocampus (HPC)-prefrontal cortex (PFC) network was observed in BEP rats. Additionally, the NOR deficits were correlated with reductions in the expression of TrkB and insulin receptor (Ir) in the CA3 region of the hippocampus. Furthermore, up-regulation of serotonin-2C (5-HT_2C) receptors in the orbitoprefrontal cortex (OFC) was associated with BM-RL deficit. Finally, in the nucleus accumbens (NAc), we found decreased dopamine receptor 2 (Drd2) expression among BEP rats. Taken together, these data suggest that binge eating vegetable shortening may induce contextual and reversal learning deficits which may be mediated, at least in part, by the altered expression of genes in the CA3-OFC-NAc neural network.

Hypothermia pretreatment improves cognitive impairment via enhancing synaptic plasticity in a traumatic brain injury model

Posttraumatic hypothermia attenuates cognitive deficits caused by TBI when it is administered at an early stage. However, little is known regarding the effect of hypothermia pretreatment on cognitive deficits one month after TBI. In the current study, the behavior test revealed that hypothermia pretreatment mitigates the learning and memory impairment induced by TBI in mice. Hypothermia treatment significantly increased the expression of PSD93, PSD95 and NR2B one month after TBI in the cortex and hippocampus compared with the normothermia group. Hypothermia pretreatment also restored the decreased spine number and the impairment in LTP and decreased the number of activated microglia one month after TBI. On the other hand, hypothermia pretreatment increased glucose metabolism in TBI mice. Taken together, these data suggested that hypothermia pretreatment is an effective method with which to prevent spine loss, maintain normal LTP and preserve learning and memory function after TBI. The neuroprotective role might be associated with the preservation of postsynaptic protein expression, the inhibition of activated microglia and the increase in glucose metabolism.

Beneficial Role of Coffee and Caffeine in Neurodegenerative Diseases: A Minireview

Coffee is among the most widespread and healthiest beverages in the world. Coffee typically contains more caffeine than most other beverages, and is widely and frequently consumed. Thus, it contributes significantly to the overall caffeine consumption within the general population, particularly in adults. Controversies regarding its benefits and risks still exist as reliable evidence is becoming available supporting its health-promoting potential. Several lines of evidence have highlighted the beneficial effects towards several disease conditions including Type II diabetes, hepatitis C virus, hepatocellular carcinoma, nonalcoholic fatty liver disease and neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic Lateral Sclerosis (ALS). The health-promoting properties of coffee are largely attributed to its rich phytochemistry, including caffeine, chlorogenic acid, caffeic acid, and hydroxy hydroquinone. In this minireview, an attempt has been made to discuss the various evidences which are mainly derived from animal and cell models. Various mechanisms chiefly responsible for the beneficial effects of caffeine have also been briefly outlined. A short note on the undesirable effects of excessive coffee intakes is also presented.

Caffeine's influence on object recognition and working-memory in prepubertal mice and its modulation by gender

OBJECTIVE

This study investigated the effects of intraperitoneal injection of caffeine on Y-maze working-memory and novel object recognition (NOR) in prepubertal mice.

METHODOLOGY

Y-maze spontaneous alternation and a novel object recognition test (consisting of acclimation, acquisition and test phases) were performed. Mice received a single dose of caffeine (10, 20, 40, 80 and 120mgkg(-1) i.p.) or vehicle, 30min before Y-maze exploration. For the NOR test, caffeine was given 30min before training and another dose 30min before test phase.

RESULTS

NOR time (acquisition phase) increased significantly in males at all doses of caffeine and decreased in females at 10, 20 and 40mg/kg compared to vehicle; during the test phase, novel object exploration time decreased significantly in males and increased in females at 10 and 20mg/kg only to decrease again at 120mg/kg. Recognition index decreased in males and increased in females while, males showed poor discrimination between novel and familiar objects compared to vehicle; while females showed increased discrimination between novel and familiar object at 10, 20,40 and 80mg/kg and a decrease at 120mg/kg. Y-maze spontaneous alternation improved significantly in males at 10 and 40mg/kg and decreased at 20 and 120mg/kg in females.

CONCLUSION

The findings suggest that acute caffeine injection improves non-spatial memory retention in female mice but not in males; spatial working-memory is however improved in males but not in females.

Exercise Prevents Memory Impairment Induced by Arsenic Exposure in Mice: Implication of Hippocampal BDNF and CREB

High concentrations of arsenic, which can be occasionally found in drinking water, have been recognized as a global health problem. Exposure to arsenic can disrupt spatial memory; however, the underlying mechanism remains unclear. In the present study, we tested whether exercise could interfere with the effect of arsenic exposure on the long-term memory (LTM) of object recognition in mice. Arsenic (0, 1, 3, and 10 mg/ kg, i.g.) was administered daily for 12 weeks. We found that arsenic at dosages of 1, 3, and 10 mg/kg decreased body weight and increased the arsenic content in the brain. The object recognition LTM (tested 24 h after training) was disrupted by 3 mg/ kg and 10 mg/ kg, but not 1 mg/ kg arsenic exposure. Swimming exercise also prevented LTM impairment induced by 3 mg/ kg, but not with 10 mg/ kg, of arsenic exposure. The expression of brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP-response element binding protein (pCREB) in the CA1 and dentate gyrus areas (DG) of the dorsal hippocampus were decreased by 3 mg/ kg and 10 mg/ kg, but not by 1 mg/ kg, of arsenic exposure. The decrease in BDNF and pCREB in the CA1 and DG induced by 3 mg/ kg, but not 10 mg/ kg, of arsenic exposure were prevented by swimming exercise. Arsenic exposure did not affect the total CREB expression in the CA1 or DG. Taken together, these results indicated that swimming exercise prevented the impairment of object recognition LTM induced by arsenic exposure, which may be mediated by BDNF and CREB in the dorsal hippocampus.

Caffeine/sleep-deprivation interaction in mice produces complex memory effects

BACKGROUND

Sleep deprivation negatively impacts memory, causing deficits in memory processes. Of interest is any agent that can offset such deficits. Mice were given varying doses of caffeine for 14 days and then deprived of sleep for 6 hours by the 'gentle handling' method. Memory was assessed using the Novel Object Recognition Test and Y maze alternation.

PURPOSE

The study was designed to ascertain the impact of varying doses of caffeine combined with total sleep-deprivation on spatial and non spatial memory in mice.

METHODS

Adult Swiss Webster mice of both sexes were assigned to six groups viz., vehicle (distilled water), or one of five selected doses of caffeine (10, 20, 40, 80 and 120 mg/kg) for 14 days via the oral route. Open field novel object recognition test and Y maze spatial working memory tests were carried out on day 14. Results were analysed using multi-factorial ANOVA followed by Tukey HSD test and expressed as mean ± S.E.M, with p values less than 0.05 were considered statistically significant.

RESULTS

Novel object recognition tests (NOR) revealed that pre-training and pre-test sleep deprivation and caffeine combination impaired non spatial and spatial memory in male and female mice.

CONCLUSION

The study shows the complex interactions with memory that may arise when total sleep deprivation is superimposed on caffeine administration.

Adenosine A(2A) receptors are necessary and sufficient to trigger memory impairment in adult mice

BACKGROUND AND PURPOSE

Caffeine (a non-selective adenosine receptor antagonist) prevents memory deficits in aging and Alzheimer's disease, an effect mimicked by adenosine A2 A receptor, but not A1 receptor, antagonists. Hence, we investigated the effects of adenosine receptor agonists and antagonists on memory performance and scopolamine-induced memory impairment in mice.

EXPERIMENTAL APPROACH

We determined whether A2 A receptors are necessary for the emergence of memory impairments induced by scopolamine and whether A2 A receptor activation triggers memory deficits in naïve mice, using three tests to assess short-term memory, namely the object recognition task, inhibitory avoidance and modified Y-maze.

KEY RESULTS

Scopolamine (1.0 mg·kg(-1) , i.p.) impaired short-term memory performance in all three tests and this scopolamine-induced amnesia was prevented by the A2 A receptor antagonist (SCH 58261, 0.1-1.0 mg·kg(-1) , i.p.) and by the A1 receptor antagonist (DPCPX, 0.2-5.0 mg·kg(-1) , i.p.), except in the modified Y-maze where only SCH58261 was effective. Both antagonists were devoid of effects on memory or locomotion in naïve rats. Notably, the activation of A2 A receptors with CGS 21680 (0.1-0.5 mg·kg(-1) , i.p.) before the training session was sufficient to trigger memory impairment in the three tests in naïve mice, and this effect was prevented by SCH 58261 (1.0 mg·kg(-1) , i.p.). Furthermore, i.c.v. administration of CGS 21680 (50 nmol) also impaired recognition memory in the object recognition task.

CONCLUSIONS AND IMPLICATIONS

These results show that A2 A receptors are necessary and sufficient to trigger memory impairment and further suggest that A1 receptors might also be selectively engaged to control the cholinergic-driven memory impairment.

Serum brain-derived neurotrophic factor levels and cocaine-induced transient psychotic symptoms

BACKGROUND

Cocaine-induced psychosis (CIP) is among the most serious adverse effects of cocaine. Reduced serum brain-derived neurotrophic factor (BDNF) levels have been reported in schizophrenia and psychosis; however, studies assessing the involvement of BDNF in CIP are lacking.

METHODS

A total of 22 cocaine-dependent patients (aged 33.65 ± 6.85) who had never experienced psychotic symptoms under the influence of cocaine (non-CIP) and 18 patients (aged 34.18 ± 8.54) with a history of CIP completed a 2-week detoxification program in an inpatient facility. Two serum samples were collected from each patient at baseline and at the end of the protocol. Demographic, consumption and clinical data were recorded for all patients. A paired group of healthy controls was also included.

RESULTS

At the beginning of the detoxification treatment, serum BDNF levels were similar in both the non-CIP and the CIP groups. During early abstinence, the non-CIP group exhibited a significant increase in serum BDNF levels (p = 0.030), whereas the CIP group exhibited a decrease. Improvements in depression (Beck Depression Inventory, BDI, p = 0.003) and withdrawal symptoms (Cocaine Selective Severity Assessment, CSSA, p = 0.013) show a significant positive correlation with serum BDNF levels in the non-CIP group, whereas no correlation between the same variables was found in the CIP group.

CONCLUSIONS

This study suggests that BDNF plays a role in the transient psychotic symptoms associated with cocaine consumption. In the non-CIP group, the increase in serum BDNF appears to be driven by the effects of chronic cocaine consumption and withdrawal. In contrast, patients with CIP share some of the neurotrophic deficiencies that characterize schizophrenia and psychosis.

Prenatal caffeine intake differently affects synaptic proteins during fetal brain development

Caffeine is the psychostimulant most consumed worldwide. However, little is known about its effects during fetal brain development. In this study, adult female Wistar rats received caffeine in drinking water (0.1, 0.3 and 1.0 g/L) during the active cycle in weekdays, two weeks before mating and throughout pregnancy. Cerebral cortex and hippocampus from embryonic stages 18 or 20 (E18 or E20, respectively) were collected for immunodetection of the following synaptic proteins: brain-derived neurotrophic factor (BDNF), TrkB receptor, Sonic Hedgehog (Shh), Growth Associated Protein 43 (GAP-43) and Synaptosomal-associated Protein 25 (SNAP-25). Besides, the estimation of NeuN-stained nuclei (mature neurons) and non-neuronal nuclei was verified in both brain regions and embryonic periods. Caffeine (1.0 g/L) decreased the body weight of embryos at E20. Cortical BDNF at E18 was decreased by caffeine (1.0 g/L), while it increased at E20, with no major effects on TrkB receptors. In the hippocampus, caffeine decreased TrkB receptor only at E18, with no effects on BDNF. Moderate and high doses of caffeine promoted an increase in Shh in both brain regions at E18, and in the hippocampus at E20. Caffeine (0.3g/L) decreased GAP-43 only in the hippocampus at E18. The NeuN-stained nuclei increased in the cortex at E20 by lower dose and in the hippocampus at E18 by moderate dose. Our data revealed that caffeine transitorily affect synaptic proteins during fetal brain development. The increased number of NeuN-stained nuclei by prenatal caffeine suggests a possible acceleration of the telencephalon maturation. Although some modifications in the synaptic proteins were transient, our data suggest that caffeine even in lower doses may alter the fetal brain development.

Sleep deprivation impairs memory, tau metabolism, and synaptic integrity of a mouse model of Alzheimer's disease with plaques and tangles

Several studies have highlighted the frequency of sleep disturbances in Alzheimer's disease (AD). However, whether they are secondary to the disease or per se increase its risk remains to be fully investigated. The aim of the current investigation was to study the effect of sleep deprivation (SD) on the development of AD phenotype in a transgenic mouse model with plaques and tangles, the 3xTg mice. We evaluated the functional and biological consequences on 3xTg mice that underwent 4 hours sleep restrain per day for 8 weeks. Compared with controls, behavioral assessment showed that SD-treated mice had a significant decline in their learning and memory. Although no differences were detected in the levels of soluble amyloid-β peptides, the same animals displayed a decrease in tau phosphorylation, which associated with a significant increase in its insoluble fraction. In addition, we observed that SD resulted in lower levels of postsynaptic density protein 95 and increased glial fibrillary acidic protein levels. Finally, although total levels of the transcription factor cellular response element binding protein were unchanged, its phosphorylated form was significantly diminished in brains of sleep-deprived mice when compared with controls. Our study underlines the importance of SD as a chronic stressor, which by modulating biochemical processes influences the development of memory impairments and AD neuropathologies. Correction of SD could be a viable therapeutic strategy to prevent the onset or slow the progression of AD in individuals bearing this risk factor.

The Janus face of caffeine

Caffeine is certainly the psychostimulant substance most consumed worldwide. Over the past years, chronic consumption of caffeine has been associated with prevention of cognitive decline associated to aging and mnemonic deficits of brain disorders. While its preventive effects have been reported extensively, the cognitive enhancer properties of caffeine are relatively under debate. Surprisingly, there are scarce detailed ontogenetic studies focusing on neurochemical parameters related to the effects of caffeine during prenatal and earlier postnatal periods. Furthermore, despite the large number of epidemiological studies, it remains unclear how safe is caffeine consumption during pregnancy and brain development. Thus, the purpose of this article is to review what is currently known about the actions of caffeine intake on neurobehavioral and adenosinergic system during brain development. We also reviewed other neurochemical systems affected by caffeine, but not only during brain development. Besides, some recent epidemiological studies were also outlined with the control of "pregnancy signal" as confounding variable. The idea is to tease out how studies on the impact of caffeine consumption during brain development deserve more attention and further investigation.

Role of state-dependent learning in the cognitive effects of caffeine in mice

Caffeine is the most widely used psychoactive substance in the world and it is generally believed that it promotes beneficial effects on cognitive performance. However, there is also evidence suggesting that caffeine has inhibitory effects on learning and memory. Considering that caffeine may have anxiogenic effects, thus changing the emotional state of the subjects, state-dependent learning may play a role in caffeine-induced cognitive alterations. Mice were administered 20 mg/kg caffeine before training and/or before testing both in the plus-maze discriminative avoidance task (an animal model that concomitantly evaluates learning, memory, anxiety-like behaviour and general activity) and in the inhibitory avoidance task, a classic paradigm for evaluating memory in rodents. Pre-training caffeine administration did not modify learning, but produced an anxiogenic effect and impaired memory retention. While pre-test administration of caffeine did not modify retrieval on its own, the pre-test administration counteracted the memory deficit induced by the pre-training caffeine injection in both the plus-maze discriminative and inhibitory avoidance tasks. Our data demonstrate that caffeine-induced memory deficits are critically related to state-dependent learning, reinforcing the importance of considering the participation of state-dependency on the interpretation of the cognitive effects of caffeine. The possible participation of caffeine-induced anxiety alterations in state-dependent memory deficits is discussed.

Modulatory effect of coffee fruit extract on plasma levels of brain-derived neurotrophic factor in healthy subjects

The present single-dose study was performed to assess the effect of whole coffee fruit concentrate powder (WCFC), green coffee caffeine powder (N677), grape seed extract powder (N31) and green coffee bean extract powder (N625) on blood levels of brain-derived neurotrophic factor (BDNF). Randomly assorted groups of fasted subjects consumed a single, 100mg dose of each material. Plasma samples were collected at time zero (T0) and at 30 min intervals afterwards, up to 120 min. A total of two control groups were included: subjects treated with silica dioxide (as placebo) or with no treatment. The collected data revealed that treatments with N31 and N677 increased levels of plasma BDNF by about 31% under these experimental conditions, whereas treatment with WCFC increased it by 143% (n 10), compared with baseline. These results indicate that WCFC could be used for modulation of BDNF-dependent health conditions. However, larger clinical studies are needed to support this possibility.