Antidepressant and Antiaging Effects of Açaí (Euterpe oleracea Mart.) in Mice.

Depression is a mental disorder that affects 300 million people of all ages worldwide, but fewer than half of those with the condition receive adequate treatment. In addition, the high pharmacological refractoriness (affecting 30%-50% of patients) and toxicity of some classical antidepressants support the pursuit of new therapies. People with this condition show depressed mood, loss of pleasure, high levels of oxidative stress, and accelerated biological aging (decreased telomere length and expression of the telomerase reverse transcriptase (TERT), the enzyme responsible for telomere maintenance). Because of the close relationship between depression and oxidative stress, nutraceuticals with antioxidant properties are excellent candidates for therapy. This study represents the first investigation of the possible antidepressant and antiaging effects of commercial samples of clarified açaí (Euterpe oleracea) juice (EO). This fruit is rich in antioxidants and widely consumed. In this study, mice were treated with saline or EO (10 µL/g, oral) for 4 days and then with saline or lipopolysaccharide (0.5 mg/kg, i.p.) to induce depressive-like behavior. Only four doses of EO were enough to abolish the despair-like and anhedonia behaviors and alterations observed in electromyographic measurements. The antidepression effect of EO was similar to that of imipramine and associated with antioxidant and antiaging effects (preventing lipid peroxidation and increasing TERT mRNA expression, respectively) in three major brain regions involved in depression (hippocampus, striatum, and prefrontal cortex). Additionally, EO significantly protected hippocampal cells, preventing neuronal loss associated with the depressive-like state and nitrite level increases (an indirect marker of nitric oxide production). Moreover, EO alone significantly increased TERT mRNA expression, revealing for the first time a potent antiaging action in the brain that suggests neuroprotection against long-term age-related consequences.

Adult Hippocampal Neurogenesis in Different Taxonomic Groups: Possible Functional Similarities and Striking Controversies.

Adult neurogenesis occurs in many species, from fish to mammals, with an apparent reduction in the number of both neurogenic zones and new neurons inserted into established circuits with increasing brain complexity. Although the absolute number of new neurons is high in some species, the ratio of these cells to those already existing in the circuit is low. Continuous replacement/addition plays a role in spatial navigation (migration) and other cognitive processes in birds and rodents, but none of the literature relates adult neurogenesis to spatial navigation and memory in primates and humans. Some models developed by computational neuroscience attribute a high weight to hippocampal adult neurogenesis in learning and memory processes, with greater relevance to pattern separation. In contrast to theories involving neurogenesis in cognitive processes, absence/rarity of neurogenesis in the hippocampus of primates and adult humans was recently suggested and is under intense debate. Although the learning process is supported by plasticity, the retention of memories requires a certain degree of consolidated circuitry structures, otherwise the consolidation process would be hampered. Here, we compare and discuss hippocampal adult neurogenesis in different species and the inherent paradoxical aspects.

In the Heart of the Amazon: Noncommunicable Diseases and Apolipoprotein E4 Genotype in the Riverine Population.

The Amazon River basin is the largest tropical forest in the world. Most of the Amazon belongs to Brazil, a developing country that currently faces huge challenges related to the consolidation of its universal healthcare system. Noncommunicable diseases (NCDs) are the leading cause of death in Brazil, accounting for 74% of all deaths, and NCDs are probably underestimated in Amazonian population because of their geographical isolation and the precariousness of riverine communities. Important risk factors, such as genetic susceptibility, remain undetermined in the riverine population. This study performed fasting blood sugar (FBS) and blood pressure measurements and investigated the presence of the ε4 allele of apolipoprotein E (APOE4) to determine the prevalence of diabetes, hypertension and the genetic risk of NCDs. FBS and APOE4 were measured in blood samples from 763 participants using spectrometry and real-time PCR; 67.5% showed altered measurements, and 57.9% had never been diagnosed or treated. Altered FBS was found in 28.3% of the participants, hypertension in 57.6% and APOE4 in 32.0%. The health profile of the riverine population appears to differ from that of urban population in the Amazon. Additional risk factors for NCDs, such as environmental contamination and nutritional transition, may contribute more than increased genetic susceptibility to the prevalence of altered FBS and hypertension. Our results will help guide the development of preventive strategies and governmental actions for more effective management of NCDs in the Amazon area.

Genetic Susceptibility to Neurodegeneration in Amazon: Apolipoprotein E Genotyping in Vulnerable Populations Exposed to Mercury.

Human exposure to mercury is a serious problem of public health in Amazon. As in other vulnerable populations throughout the world, Amazonian riverine populations are chronically exposed to this metal and some symptoms of mercury intoxication were already detected in these populations. However, studies on the genetic susceptibility to mercury toxicity in the Amazon are scarce, and they tested a limited number of individuals. In this context, apolipoprotein E gene (APOE) is a key element with a well-established association among their alleles and the neurodegenerative consequences of mercury intoxication. However, no studies have addressed APOE genotyping in Amazonian exposed populations. Additionally, epidemiological studies with APOE genotyping in Amazon have been restricted to indigenous populations. Therefore, this work analyzed for the first time the genotypic and allelic profiles of APOE in Amazonian riverine populations chronically exposed to mercury. Eight hundred and twenty three individuals were enrolled in our study donating blood (794) and/or hair (757). APOE genotyping was analyzed by real-time PCR. Total mercury and mercury species were quantified by ICP-MS and GC-pyro-AFS, respectively. Genomic ancestry markers were evaluated by multiplex-PCR reaction, separated by capillary electrophoresis on the ABI 3130 Genetic Analyzer instrument and analyzed on GeneMapper ID v3.2. The 𝜀3 and 𝜀3/𝜀3 were the most frequent allele and genotype, respectively, followed by 𝜀4 allele and 𝜀3/𝜀4 genotype. Only 𝜀2/𝜀2 genotype was not found, suggesting that the absence of this genotype is a generalized phenomenon in Amazon. Also, our data supported an association between the presence of APOE4 and the Amerindian origin in these populations. Fifty-nine individuals were identified at maximum risk with levels of mercury above 10 µg/g and the presence of APOE4. Interestingly, among individuals with high mercury content, APOE4-carriers had high mercury levels than APOE2-carriers, pointing to a different heavy metal accumulation according to the APOE allele. These data suggest that APOE4, in addition to a possible pharmacodynamic effect, may influence pharmacokinetically the mercury exposure causing its higher accumulation and leading to worse deleterious consequences. Our results may aid in the development of prevention strategies and health policy decision-making regarding these at-risk vulnerable populations.

Clarified Açaí (Euterpe oleracea) Juice as an Anticonvulsant Agent: In Vitro Mechanistic Study of GABAergic Targets.

Seizures affect about 50 million people around the world. Approximately 30% of seizures are refractory to the current pharmacological arsenal, so, the pursuit of new therapeutic alternatives is essential. Clarified Euterpe oleracea (EO) juice showed anticonvulsant properties similar to diazepam in an in vivo model with pentylenetetrazol, a GABAA receptor blocker. This study investigated the effects of EO on the main GABAergic targets for anticonvulsant drugs, analyzing the effect on the GABA receptor's benzodiazepine and picrotoxinin binding sites and the GABA uptake. Primary cultures of cortical neurons and astrocytes were treated with EO (0-25%) for up to 90 min. [3H]Flunitrazepam and [3H]TBOB binding, [3H]GABA uptake, cell viability, and morphology were assayed. Nonlethal concentrations of EO increased agonist binding and decreased antagonist binding in cortical neurons. Low concentrations significantly inhibited GABA uptake, especially in astrocytes, suggesting an accumulation of endogenous GABA in the synaptic cleft. The results demonstrate, for the first time, that EO can improve GABAergic neurotransmission via interactions with GABAA receptor and modulation of GABA uptake. Understanding these molecular mechanisms will help in the treatment of seizures and epilepsy, especially in developing countries where geographic isolation and low purchasing power are the main barriers to access to adequate treatment.

Large-scale projects in the amazon and human exposure to mercury: The case-study of the Tucuruí Dam.

The Tucuruí Dam is one of the largest dams ever built in the Amazon. The area is not highly influenced by gold mining as a source of mercury contamination. Still, we recently noted that one of the most consumed fishes (Cichla sp.) is possibly contaminated with methylmercury. Therefore, this work evaluated the mercury content in the human population living near the Tucuruí Dam. Strict exclusion/inclusion criteria were applied for the selection of participants avoiding those with altered hepatic and/or renal functions. Methylmercury and total mercury contents were analyzed in hair samples. The median level of total mercury in hair was above the safe limit (10µg/g) recommended by the World Health Organization, with values up to 75µg/g (about 90% as methylmercury). A large percentage of the participants (57% and 30%) showed high concentrations of total mercury (≥ 10µg/g and ≥ 20µg/g, respectively), with a median value of 12.0µg/g. These are among the highest concentrations ever detected in populations living near Amazonian dams. Interestingly, the concentrations are relatively higher than those currently shown for human populations highly influenced by gold mining areas. Although additional studies are needed to confirm the possible biomagnification and bioaccumulation of mercury by the dams in the Amazon, our data already support the importance of adequate impact studies and continuous monitoring. More than 400 hydropower dams are operational or under construction in the Amazon, and an additional 334 dams are presently planned/proposed. Continuous monitoring of the populations will assist in the development of prevention strategies and government actions to face the problem of the impacts caused by the dams.

Is Low Non-Lethal Concentration of Methylmercury Really Safe? A Report on Genotoxicity with Delayed Cell Proliferation.

Human exposure to relatively low levels of methylmercury is worrying, especially in terms of its genotoxicity. It is currently unknown as to whether exposure to low levels of mercury (below established limits) is safe. Genotoxicity was already shown in lymphocytes, but studies with cells of the CNS (as the main target organ) are scarce. Moreover, disturbances in the cell cycle and cellular proliferation have previously been observed in neuronal cells, but no data are presently available for glial cells. Interestingly, cells of glial origin accumulate higher concentrations of methylmercury than those of neuronal origin. Thus, the aim of this work was to analyze the possible genotoxicity and alterations in the cell cycle and cell proliferation of a glioma cell line (C6) exposed to a low, non-lethal and non-apoptotic methylmercury concentration. Biochemical (mitochondrial activity) and morphological (integrity of the membrane) assessments confirmed the absence of cell death after exposure to 3 µM methylmercury for 24 hours. Even without promoting cell death, this treatment significantly increased genotoxicity markers (DNA fragmentation, micronuclei, nucleoplasmic bridges and nuclear buds). Changes in the cell cycle profile (increased mitotic index and cell populations in the S and G2/M phases) were observed, suggesting arrest of the cycle. This delay in the cycle was followed, 24 hours after methylmercury withdrawal, by a decrease number of viable cells, reduced cellular confluence and increased doubling time of the culture. Our work demonstrates that exposure to a low sublethal concentration of MeHg considered relatively safe according to current limits promotes genotoxicity and disturbances in the proliferation of cells of glial origin with sustained consequences after methylmercury withdrawal. This fact becomes especially important, since this cellular type accumulates more methylmercury than neurons and displays a vital role protecting the CNS, especially in chronic intoxication with this heavy metal.

Antidepressant drugs in convulsive seizures: Pre-clinical evaluation of duloxetine in mice.

Convulsive seizures (CS) are deleterious consequences of acute cerebral insults and prejudicial events in epilepsy, affecting more than 50 million people worldwide. Molecular mechanisms of depression and epilepsy include an imbalance between excitatory and inhibitory neurotransmission provoking oxidative stress (OS). OS is intimately linked to the origin and evolution of CS and is modulated by antidepressant and anticonvulsant drugs. Although newer antidepressants have exhibited a possible protective role in CS, studies analyzing serotonin and norepinephrine reuptake inhibitors merit to be further investigated. Thus, this study challenged the traditional model of pentylenetetrazol-induced CS, with only one administration of duloxetine. Male Swiss mice were treated with duloxetine (dose corresponding to the therapeutic range for human depression or greater, by allometric calculation; 10, 20 or 40 mg/kg), 30 min before pentylenetetrazol. Behavioral and electroencephalographic alterations were monitored. Lipid peroxidation, nitrites and catalase and superoxidase activities were measured in cortex. Behavioral and electroencephalographic results suggested a possible biphasic effect of duloxetine on CS, with anticonvulsant actions at therapeutic doses and a proconvulsant effect at higher doses. Duloxetine (20 mg/kg) also prevented lipid peroxidation and decreased catalase and superoxide dismutase activities in the cerebral cortex, with no influence on nitrites levels. These data demonstrated an anticonvulsant effect of duloxetine in CS for the first time. This extra anticonvulsant effect may allow the doses of anticonvulsants to be reduced, causing fewer side effects and possibly decreasing morbidity and mortality due to drug interactions in polytherapy.

Anticonvulsant properties of Euterpe oleracea in mice.

Açai (Euterpe oleracea Mart.), a highly consumed fruit in Amazon, is from a common palm with remarkable antioxidant properties. Because oxidative stress and seizures are intimately linked, this study investigated the potential neuroprotective and anticonvulsant effects of commercial clarified açai juice (EO). EO did not alter spontaneous locomotor activity. Four doses of EO were sufficient to increase latencies to both first myoclonic jerk and first generalized tonic-clonic seizure and significantly decrease the total duration of tonic-clonic seizures caused by pentylenetetrazol administration. Also, electrocortical alterations provoked by pentylenetetrazol were prevented, significantly decreasing amplitude of discharges and frequencies above 50 Hz. EO was also able to completely prevent lipid peroxidation in the cerebral cortex, showing a potent direct scavenging property. These results demonstrate for the first time that E. oleracea significantly protects against seizures and seizure-related oxidative stress, indicating an additional protection for humans who consume this fruit.

Genotoxicity of mercury: contributing for the analysis of Amazonian populations.

Mercury is an important source of environmental contamination affecting human beings throughout the world and especially in the Amazon. Riverside populations have been chronically exposed to relatively high levels of methylmercury for many years. Long-term effects of mercury exposure are not well known, but human genotoxicity was already showed in both in vitro and epidemiological studies. However, to date, only two studies were carried out in Amazonian populations with conflicting results and without comparing to a non-exposed population. Aiming to highlight this question and avoid interference factors, this work analyzed in vitro genotoxicity of mercury in blood lymphocytes of Amazonian individuals by two methods (micronucleus and chromosomal aberrations). Deleterious effects of low levels (1-500 µg/l or 0,004-2 µM) of methylmercury were only detected with the method to detect chromosomal aberrations. Mitotic index (proportion of cells in metaphase) was the parameter most sensible. Thus, this technique was applied for the analysis of an Amazonian non-exposed population (Panacauera) with similar social-economical characteristics of the exposed populations studied elsewhere. The mean of the mitotic index for Panacauera population was 0.0814 ± 0.0097. Inter-individual variability of this index had no relation with sex or age. This value was above those registered for some groups of exposed populations. This fact points to mercury as the main responsible for inhibiting the cell cycle and/or the loss of proliferative capacity of the cells. These results already support mitotic index as an essential parameter for the early diagnose of mercury genotoxicity in humans, and especially in Amazonian populations.

Mercury and human genotoxicity: critical considerations and possible molecular mechanisms.

Mercury compounds versatility explains their numerous applications in diverse areas of industry. The growing use of this metal has resulted in a significant increase of environment contamination and episodes of human intoxication, arousing the concern of international organisms. Meanwhile, consequences of these intoxication outbreaks are still not fully understood, especially if we consider long-term effects of chronic exposure to relatively low levels of mercury compounds. In the present manuscript, studies about the genotoxicity of mercury compounds, performed in vitro, in vivo, and/or including epidemiologic studies of human populations were reviewed. Some mercury compounds are known as teratogenic agents, especially affecting the normal development of the central nervous system; however, the connection between mercury exposure and carcinogenesis remains controversial. Since 1990s, epidemiological studies have begun to include an increasing number of human subjects, making the results more reliable: thus, increased genotoxicity was demonstrated in human populations exposed to mercury through diet, occupation or by carrying dental fillings. In fact, concentrations of methylmercury causing significant genotoxic alterations in vitro below both safety limit and concentration were associated with delayed psychomotor development with minimal signs of methylmercury poisoning. Based on mercury's known ability to bind sulfhydryl groups, several hypotheses were raised about potential molecular mechanisms for the metal genotoxicity. Mercury may be involved in four main processes that lead to genotoxicity: generation of free radicals and oxidative stress, action on microtubules, influence on DNA repair mechanisms and direct interaction with DNA molecules. All data reviewed here contributed to a better knowledge of the widespread concern about the safety limits of mercury exposure.