Hop Bitter Acids Increase Hippocampal Dopaminergic Activity in a Mouse Model of Social Defeat Stress

Hop (Humulus lupulus L.) extract reverts glycaemic imbalance and cognitive impairment in an animal model of obesity

The rates of overweight and obesity around the world have increased in past years. The body's adipose tissue stimulates the antioxidant and oxidation imbalance capacity at the cellular level. This scenario favors an inflammatory low-grade systemic condition starting with insulin resistance, which in turn may involve diabetes mellitus type 2 and cognitive decline afterward. Neurological diseases have been correlated to senile age diseases over time. This scenario calls for a change in the incidence of obesity in the younger generation. An unhealthy dietary consumption together with sedentary habits might lead to poor gut absorption of nutrients. Several plants and foods have bioactive compounds that can reduce or inhibit radical scavengers, reactive oxygen species, and metal ion complexes that threaten the cerebral defense system. The bitter acids from hops (Humulus lupulus L.) have been demonstrated to have promising effects on lipid and carbohydrate metabolism improvement, reducing inflammatory responses through alpha acids, beta acids, and analogs action. Therefore, the current study aimed to investigate the bioactivity of hop bitter acids in obese and lean mice. For that, a dry hop extract (DHE) was obtained by applying carbon dioxide as the fluid of supercritical extraction. Afterward, seventy-eight male mice of the C57BL/6J strain were weighed and randomly distributed into six groups of 13 animals each according to the diet offered: (NO) normolipidic diet, (NO1) normolipidic diet containing 0.35% alpha acids, (NO2) normolipidic diet containing 3.5% alpha acids, (HP) hyperlipidic diet, (HP1) hyperlipidic diet containing 0.35% alpha acids, and (HP2) hyperlipidic diet containing 3.5% alpha acids. After applying the glycemic tolerance and insulin tolerance tests, a better stabilization of glycemia levels and weight gain among those animals fed with DHE (NO2 and HP2) were observed in comparison to the obese control group (HP) (p < 0.05). There was also an amelioration of antioxidant capacity observed by checking the enzymatic profile by SOD and an apparent mitigation of brain degeneration by checking GSK3β and p-IRS1 proteins expression (p < 0.05). The y-maze cognitive test applied to highlight possible obesity-harmful animal brains did not indicate a statistical difference between the groups. Although the weekly dietary intake between the obese HP2 group (33.32 ± 4.11, p < 0.05) and control HP (42.3 ± 5.88, p < 0.05) was different. The bioactive compounds present in DHE have demonstrated relevant effects on glycemic control, insulin signaling, and the consequent modulatory action of the obesity-related markers with the brain's inflammatory progression.

Assessing the role of antioxidant and pro-oxidant balance in mediating the relationship between vitamin K intake and depressive symptoms in adults

Background

Growing evidence suggests a link between vitamin K (VK) intake and depression, although the underlying mechanisms remain unclear. We aimed to investigate whether oxidative balance scores (OBS) mediate the association between VK intake and depression in participants from the National Health and Nutrition Examination Survey (NHANES) 2007-2018.

Methods

We analyzed data from 30,408 individuals. Dietary VK intake served as the independent variable, depression symptoms as the outcome variable, and OBS as the mediator. Multivariable logistic regression and restricted cubic splines assessed the associations. Mediation analysis was conducted to evaluate the potential mediating role of OBS.

Results

Higher dietary VK intake was associated with lower depression risk in the multivariate model. Compared to the lowest log2 VK quartile, those in the higher quartiles had significantly lower depression odds (Q3: OR 0.66, 95% CI 0.55-0.78; Q4: OR 0.64, 95% CI 0.52-0.78). Additionally, a 1-unit increase in log2 VK intake was associated with a 15% decrease in depression odds (OR 0.85, 95% CI 0.81-0.90). Restricted cubic splines revealed a non-linear relationship between log2 VK and depression (p for non-linearity <0.001). Notably, OBS mediated 26.09% (p < 0.001) of the association between log2 VK and depression.

Conclusion

Higher VK intake is associated with reduced depression risk, potentially mediated by oxidative balance. Further research is warranted to confirm causality and elucidate the underlying mechanisms.

Pharmacological Studies on Neuromodulatory Effects of Plant Extracts

Central nervous system (CNS) disorders represent a public health priority and demand significant scientific efforts for the development and study of new drugs and their possible beneficial effects [...].

Ecological validity of social defeat stressors in mouse models of vulnerability and resilience

Laboratory mouse models offer opportunities to bridge the gap between basic neuroscience and applied stress research. Here we consider the ecological validity of social defeat stressors in mouse models of emotional vulnerability and resilience. Reports identified in PubMed from 1980 to 2020 are reviewed for the ecological validity of social defeat stressors, sex of subjects, and whether results are discussed in terms of vulnerability alone, resilience alone, or both vulnerability and resilience. Most of the 318 reviewed reports (95%) focus on males, and many reports (71%) discuss vulnerability and resilience. Limited ecological validity is associated with increased vulnerability and decreased resilience. Elements of limited ecological validity include frequent and repeated exposure to defeat stressors without opportunities to avoid or escape from unfamiliar conspecifics that are pre-screened and selected for aggressive behavior. These elements ensure defeat and may be required to induce vulnerability, but they are not representative of naturalistic conditions. Research aimed at establishing causality is needed to determine whether ecologically valid stressors build resilience in both sexes of mice.

Resilience to the effects of social stress on vulnerability to developing drug addiction

We review the still scarce but growing literature on resilience to the effects of social stress on the rewarding properties of drugs of abuse. We define the concept of resilience and how it is applied to the field of drug addiction research. We also describe the internal and external protective factors associated with resilience, such as individual behavioral traits and social support. We then explain the physiological response to stress and how it is modulated by resilience factors. In the subsequent section, we describe the animal models commonly used in the study of resilience to social stress, and we focus on the effects of chronic social defeat (SD), a kind of stress induced by repeated experience of defeat in an agonistic encounter, on different animal behaviors (depression- and anxiety-like behavior, cognitive impairment and addiction-like symptoms). We then summarize the current knowledge on the neurobiological substrates of resilience derived from studies of resilience to the effects of chronic SD stress on depression- and anxiety-related behaviors in rodents. Finally, we focus on the limited studies carried out to explore resilience to the effects of SD stress on the rewarding properties of drugs of abuse, describing the current state of knowledge and suggesting future research directions.

Effect of non-alcoholic beer containing matured hop bitter acids on mood states in healthy adults: A single-arm pilot study

This study aimed to investigate the effect of non-alcoholic beer containing matured hop bitter acids on mood states among healthy adults older than 20 years. This study was an open-label longitudinal intervention design in which each participant served as their control. For three weeks, we evaluated the effect of non-alcoholic beer containing 35 mg of matured hop bitter acids on mood, sleep quality, and work performance. The data of 97 participants (age range: 23-72 years, median age: 42) were analyzed. After the intervention, we found that matured hop bitter acids significantly improved total mood state, including anxiety, depression, fatigue, and vigor, compared with the baseline. Furthermore, sleep quality and absolute presenteeism were significantly improved after the intervention compared with the baseline. The present exploratory study suggested that 3-week supplementation with matured hop bitter acids improved mood and peripheral symptoms in persons of a wide range of ages. Although further investigation is needed, the findings suggested that non-alcoholic beer in daily life might become a choice for maintaining mood states. This article is protected by copyright. All rights reserved.

Redox and Anti-Inflammatory Properties from Hop Components in Beer-Related to Neuroprotection

Beer is a fermented beverage widely consumed worldwide with high nutritional and biological value due to its bioactive components. It has been described that both alcoholic and non-alcoholic beer have several nutrients derived from their ingredients including vitamins, minerals, proteins, carbohydrates, and antioxidants that make beer a potential functional supplement. Some of these compounds possess redox, anti-inflammatory and anticarcinogenic properties making the benefits of moderate beer consumption an attractive way to improve human health. Specifically, the hop cones used for beer brewing provide essential oils, bitter acids and flavonoids that are potent antioxidants and immune response modulators. This review focuses on the redox and anti-inflammatory properties of hop derivatives and summarizes the current knowledge of their neuroprotective effects.