Chronic unpredictable stress-induced inflammation and quantitative analysis of neurons of distinct brain regions in Wistar rat model of comorbid depression

Protective role of virgin coconut oil on potent biochemical biomarkers in Wistar rat model of comorbid depression

Objective

Chronic stress arises from stressful situations in day-to-day life that are ignored or managed incorrectly. Long-term stress can have negative effects, especially when it plays a role in the development of neurological illnesses. Severe stress can also negatively impact emotional well-being. Virgin coconut oil (VCO) has numerous health advantages. The aim of this study was to assess how VCO affected the biochemical and behavioral characteristics of Wistar albino rats exposed to chronic, unpredictable stress.

Materials and Methods

Healthy Wistar albino rats (150-200 gm) were split into two groups: experimental group and control group. Based on stress exposure and treatment with VCO and antidepressants, they were further divided into various subgroups. A chronic, unpredictable stress procedure was given for 21 days. After the experimental procedure, the rats were anesthetized, and through a cardiac puncture, blood was collected. The liver and brain were dissected to estimate different biochemical markers.

Results

VCO proved to be a protective agent against chronic, unpredictable stress-induced changes in the biochemical parameters, hepatic enzyme activity, lipid profile, oxidative stress, and cognition.

Conclusion

VCO might be helpful as an effective natural treatment that can be utilized to effectively combat chronic, unpredictable stress-induced changes in brain and liver tissue.

Impact of Stress on Brain Morphology: Insights into Structural Biomarkers of Stress-related Disorders

Exposure to acute and chronic stress has a broad range of structural effects on the brain. The brain areas commonly targeted in the stress response models include the hippocampus, the amygdala, and the prefrontal cortex. Studies in patients suffering from the so-called stress-related disorders -embracing post-traumatic stress, major depressive and anxiety disorders- have fairly replicated animal models of stress response -particularly the neuroendocrine and the inflammatory models- by finding alterations in different brain areas, even in the early neurodevelopment. Therefore, this narrative review aims to provide an overview of structural neuroimaging findings and to discuss how these studies have contributed to our knowledge of variability in response to stress and the ulterior development of stress-related disorders. There are a gross number of studies available but neuroimaging research of stress-related disorders as a single category is still in its infancy. Although the available studies point at particular brain circuitries involved in stress and emotion regulation, the pathophysiology of these abnormalities -involving genetics, epigenetics and molecular pathways-, their relation to intraindividual stress responses -including personality characteristics, self-perception of stress conditions…-, and their potential involvement as biomarkers in diagnosis, treatment prescription and prognosis are discussed.

Preventive effect of peptides derived from fermented milk on chronic stress-induced brain damage and intestinal dysfunction in mice

This study investigated the preventive effects of peptides derived from milk fermented with the probiotic strain Lactobacillus gasseri 505 (505) against stress-related brain damage and anxiety-like behavior. The peptides MKPWIQPKTKVIPYVRYL (Pep14) and VYQHQKAMKPWIQPKTKVIPYVRYL (Pep21), which exhibit high antioxidant and anti-inflammatory activities, were administered to stressed mice. The results showed that the stress mechanism in the gut-brain axis was regulated by pretreatment with both peptides, leading to inhibition of neurodevelopment and neuroinflammation through the hypothalamic-pituitary-adrenal (HPA) axis, based on the expression of related mRNA and proteins. The expression of colonic inflammation-related mRNA and proteins was also reduced. Moreover, anxiety-like behavior was significantly reduced in mice treated with Pep14 and Pep21. These results indicate that the bioactive peptides Pep14 and Pep21, derived from milk fermented with 505, may prevent stress-induced brain damage and anxiety-like behavior via regulation of the HPA axis.

Amelioration of modified chronic unpredictable stress using Celastrus paniculatus seed oil alone and in combination with fluoxetine

The various stressors in chronic unpredictable stress (CUS) triggers depressive behavior, impairs learning, and decision-making abilities. The present study investigated the effects of Celastrus paniculatus seed oil (CPSO) alone and in combination with fluoxetine (FLU) in modified CUS (mCUS) induced depression in mice. In this study, adult albino mice were subjected to a modified version of CUS protocol having six different stressors and were applied daily consistently for 15 days. The post-treatment with CPSO (50 and 100 mg/kg) and FLU (10 mg/kg) alone and in combination from day 16th to 36th. Group I: normal control; group II: diseased control (mCUS subjected group); group III: CPSO (50 mg/kg); group IV: CPSO (100 mg/kg); group V: CPSO (50 mg/kg)+FLU (10 mg/kg); group VI: CPSO (100 mg/kg)+FLU (10 mg/kg); group VII: FLU (10 mg/kg); group VIII: FLU (20 mg/kg). During experimentation, various behavioral, biochemical, oxidative stress, inflammatory, and neurotransmitters level were checked. The CUS treated mice exhibited increased escaped latency, decreased number of open arm entries, increased immobility time, decreased percentage of sucrose consumption, and number of the boxes crossed as compared to the normal group. The post-treatment with the CPSO 50 + FLU 10, CPSO 100 + FLU 10, FLU 10 significantly (p < 0.05) attenuated behavioral, biochemical, inflammation, corticosteroid, and neurotransmitters level as compared to CPSO 50, CPSO 100, and FLU 20 alone. CPSO along with FLU appreciably achieved anti-depressant effect via lowering stress, inflammation, corticosteroid level, and restoration of neurotransmitters level in mCUS induced depression mice model.

Protective role of cod liver oil on hippocampal oxidative damage and neuronal count in Wistar rat model of comorbid depression

Background

Proper nutrition and balanced diet have a profound influence on mental well-being. Nutritional psychiatry plays an important role in influencing a healthy mind and body. The animal model of chronic unpredictable stress has been considered the effective model to explore research on anxiety and depression.

Aim

The present study aimed to explore the protective role of cod liver oil on various biochemical and neuronal analyses in the hippocampus tissue of the Wistar rat model of comorbid depression.

Methods

Healthy adult albino rats of Wistar strain weighing (120-160 g) were divided into control groups and experimental groups. These groups were further categorized into various subgroups based on stress exposure, cod liver oil, and antidepressant treatment. Six animals were taken in each group. The duration of stress exposure was for 15 days. After the experimentation procedure, the animals were anesthetized and hippocampus was dissected for the estimations of various biochemical and neurological parameters.

Results

The combination of cod liver oil with the antidepressant significantly (p < 0.001) decreased the lipid peroxidation level. Total antioxidant (TAO) and superoxide dismutase (SOD) levels significantly increased (p < 0.001) in the hippocampus. Treatment of cod liver oil during the stress exposure increased (p < 0.001) the neuronal count.

Conclusion

Cod liver oil proved to be an effective antidepressant agent by increasing the antioxidants and promoting neurogenesis in the hippocampus.

The Neurobiological Links between Stress and Traumatic Brain Injury: A Review of Research to Date

Neurological dysfunctions commonly occur after mild or moderate traumatic brain injury (TBI). Although most TBI patients recover from such a dysfunction in a short period of time, some present with persistent neurological deficits. Stress is a potential factor that is involved in recovery from neurological dysfunction after TBI. However, there has been limited research on the effects and mechanisms of stress on neurological dysfunctions due to TBI. In this review, we first investigate the effects of TBI and stress on neurological dysfunctions and different brain regions, such as the prefrontal cortex, hippocampus, amygdala, and hypothalamus. We then explore the neurobiological links and mechanisms between stress and TBI. Finally, we summarize the findings related to stress biomarkers and probe the possible diagnostic and therapeutic significance of stress combined with mild or moderate TBI.

Unexpected Consequences of Noise-Induced Hearing Loss: Impaired Hippocampal Neurogenesis, Memory, and Stress

Noise-induced hearing loss (NIHL), caused by direct damage to the cochlea, reduces the flow of auditory information to the central nervous system, depriving higher order structures, such as the hippocampus with vital sensory information needed to carry out complex, higher order functions. Although the hippocampus lies outside the classical auditory pathway, it nevertheless receives acoustic information that influence its activity. Here we review recent results that illustrate how NIHL and other types of cochlear hearing loss disrupt hippocampal function. The hippocampus, which continues to generate new neurons (neurogenesis) in adulthood, plays an important role in spatial navigation, memory, and emotion. The hippocampus, which contains place cells that respond when a subject enters a specific location in the environment, integrates information from multiple sensory systems, including the auditory system, to develop cognitive spatial maps to aid in navigation. Acute exposure to intense noise disrupts the place-specific firing patterns of hippocampal neurons, "spatially disorienting" the cells for days. More traumatic sound exposures that result in permanent NIHL chronically suppresses cell proliferation and neurogenesis in the hippocampus; these structural changes are associated with long-term spatial memory deficits. Hippocampal neurons, which contain numerous glucocorticoid hormone receptors, are part of a complex feedback network connected to the hypothalamic-pituitary (HPA) axis. Chronic exposure to intense intermittent noise results in prolonged stress which can cause a persistent increase in corticosterone, a rodent stress hormone known to suppress neurogenesis. In contrast, a single intense noise exposure sufficient to cause permanent hearing loss produces only a transient increase in corticosterone hormone. Although basal corticosterone levels return to normal after the noise exposure, glucocorticoid receptors (GRs) in the hippocampus remain chronically elevated. Thus, NIHL disrupts negative feedback from the hippocampus to the HPA axis which regulates the release of corticosterone. Preclinical studies suggest that the noise-induced changes in hippocampal place cells, neurogenesis, spatial memory, and glucocorticoid receptors may be ameliorated by therapeutic interventions that reduce oxidative stress and inflammation. These experimental results may provide new insights on why hearing loss is a risk factor for cognitive decline and suggest methods for preventing this decline.

Early experience unpredictability in child development as a model for understanding the impact of the COVID-19 pandemic: A translational neuroscience perspective

Extensive evidence links adverse experiences during childhood to a wide range of negative consequences in biological, socioemotional, and cognitive development. Unpredictability is a core element underlying most forms of early adversity; it has been a focus of developmental research for many years and has been receiving increasing attention recently. In this article, we propose a conceptual model to describe how unpredictable and adverse early experiences affect children's neurobiological, behavioral, and psychological development in the context of the COVID-19 pandemic. We first highlight the critical role of unpredictability in child development by reviewing existing conceptual models of early adversity as they relate to subsequent development across the lifespan. Then, we employ a translational neuroscience framework to summarize the current animal- and human-based evidence on the neurobiological alterations induced by early experience unpredictability. We further argue that the COVID-19 pandemic serves as a global "natural experiment" that provides rare insight to the investigation of the negative developmental consequences of widespread, clustered, and unpredictable adverse events among children. We discuss how the pandemic helps advance the science of unpredictable early adverse experiences. As unpredictability research continues to grow, we highlight several directions for future studies and implications for policymaking and intervention practices.

Brain-derived Neurotropic factor (BDNF) mediates the protective effect of Cucurbita pepo L. on salivary glands of rats exposed to chronic stress evident by structural, biochemical and molecular study

BACKGROUND

Acute and chronic stresses affect the salivary glands, representing the source of plasma BDNF during stressful conditions. Pumpkin is a medicinal plant with an evident antioxidant, anti-inflammatory and potential antidepressant effects.

OBJECTIVE

To assess the structural and biochemical effects induced by exposure to chronic unpredictable mild stress (CUMS) on salivary glands of albino rats, and to evaluate the role of pumpkin extract (Pump) in ameliorating this effect.

METHODOLOGY

Four groups (n=10 each) of male albino rats were included in this study: the control, CUMS, Fluoxetine-treated and Pump-treated. The corticosterone, the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), and the oxidant/antioxidant profile were all assessed in the serum. The level of BDNF mRNA was measured in the salivary glands using qRT-PCR. Histopathological changes of the salivary glands were also assessed.

RESULTS

The depressive-like status was confirmed behaviorally and biochemically. Exposure to CUMS significantly up-regulated (p<0.001) the level of serum corticosterone. CUMS induced degenerative changes in the secretory and ductal elements of the salivary glands evident by increased apoptosis. Both Fluoxetine and Pumpkin significantly up-regulated (p<0.001) BDNF expression in the salivary glands and ameliorated the CUMS-induced histopathological and biochemical alterations in the salivary glands. Pumpkin significantly (p<0.001) increased the serum levels of antioxidant enzymes SOD, GPX and CAT, and reduced the serum levels of the pro-inflammatory cytokines TNF-α, IL-6.

CONCLUSION

Pumpkin ameliorates the depressive-like status induced in rats following exposure to chronic stress through exerting a promising anti-inflammatory, antioxidant and anti-depressant-like effects. The pumpkin, subsequently, improved stress-induced structural changes in the salivary glands that might be due to up-regulation of BDNF expression in the glands.