Summary: Stress is a universal experience, but not all stress affects the brain in the same way. A new study in rats reveals that acute stress provokes anxiety-like behaviors, especially in males, while chronic stress is more strongly tied to depressive symptoms.
Researchers also found changes in key blood-brain barrier proteins, showing that stress compromises brain defenses in different ways depending on duration and sex. These findings underline the importance of tailoring mental health prevention and treatment strategies to both stress type and biological differences.
Key Facts
- Acute Stress: Triggers anxiety-like behaviors, especially in males.
- Chronic Stress: More strongly linked to depressive symptoms and blood-brain barrier changes.
- Sex Differences: Stress impacts male and female brains differently, suggesting tailored interventions are needed.
Source: BIAL Foundation
A study analyses the negative effects of stress on the brains of male and female rats and concludes that acute stress induces anxiety-like behaviors, especially in males, while chronic stress is moreassociated with depressive symptoms.
Understanding these differences may help develop more effective approaches to preventing and treating mental disorders such as anxiety and depression.
It is well established that stress can increase susceptibility to various neuropsychiatric disorders, such as depression and anxiety, which are highly prevalent worldwide and represent a significant economic burden and public health issue in our society. The World Health Organization estimated that in 2019, around 970 million people globally – one in eight – suffered from a mental disorder.
Evidence also points to sex differences in the prevalence of and responses to stress. In fact, while women account for two-thirds of patients with stress-related disorders, another indicator shows that more than two-thirds of suicide victims are men.
Although stress is a part of life and, in small doses, can even be beneficial, excessive exposure, whether acute or chronic, can have profound negative effects, especially on the brain, potentially leading to cerebrovascular diseases.
One of the most sensitive targets of excessive stress is the blood-brain barrier, a structure that protects the brain from potentially harmful substances.
However, despite evidence suggesting that different types of stress can compromise its integrity and trigger neuroinflammatory responses associated with various neurological conditions, the cellular and molecular mechanisms underlying these effects remain poorly understood.
In the article “Distinct behavioural and neurovascular signatures induced by acute and chronic stress in rats”, published in September in the scientific journal Behavioural Brain Research, a research team from the University of Coimbra, led by Ana Paula Silva, sought to clarify this issue by analysing the effects of acute and chronic stress in rodents.
With support from the BIAL Foundation, the researchers used open field and forced swimming tests to assess locomotor activity and anxiety- and depression-like behaviors in male and female Wistar rats.
The results showed that acute stress induces anxiety-like behaviors, especially in males, while chronic stress is more associated with depressive symptoms. Additionally, changes were observed in key proteins of the blood-brain barrier, with significant sex differences.
The research confirmed that acute stress and so-called chronic mild unpredictable stress induce distinct behavioural and biochemical profiles, highlighting the importance of differentiating stress types and considering biological variables, such as sex, in neuroscience research.
“Our study shows how important it is to understand the differences between types of stress to better grasp the causes of mental disorders like anxiety and depression, and to find more effective ways to prevent and treat these issues”, explains Ana Paula Silva.
About this stress and mental health research news
Author: Sandra Pinto
Source: BIAL Foundation
Contact: Sandra Pinto – BIAL Foundation
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Distinct behavioural and neurovascular signatures induced by acute and chronic stress in rats” by Ana Paula Silva et al. Behavioural Brain Research
Abstract
Distinct behavioural and neurovascular signatures induced by acute and chronic stress in rats
Stress is a contributing factor for several mood disorders, including depression and anxiety which are associated with significant changes in behavioural and cellular domains.
Additionally, sex differences in the prevalence of these neuropsychiatric disorders are well established.
Emerging evidence suggests that stress is linked to cerebrovascular diseases and that blood-brain barrier (BBB) dysfunction contributes to the development and exacerbation of neuropathology and neuroinflammation.
Despite these interesting findings, very little attention has been given to the effect of both acute and chronic stress (unpredictable chronic mild stress-uCMS) on the link between behavioural and BBB alterations.
In this study we used the open field and forced swimming tests (FST) to evaluate locomotor activity, anxiety- and depressive-like behaviours in male and female Wistar rats.
Western blotting or ELISA were used to quantify the levels of different proteins related to BBB components and neuroinflammation in the prefrontal cortex. We found that acute stress induced anxiety only in males, whereas uCMS had no effect.
Additionally, acute stress decreased immobility time in the FST pointing to a coping strategy in both sexes. In contrast, uCMS increased immobility time only in males, indicating depressive-like behaviour.
Additionally, both types of stress had no major impact on TNF-α, GFAP and C3/C3aR proteins. Nevertheless, acute stress significantly reduced occludin and VEGF protein levels in both sexes, highlighting significant alterations in the neurovasculature.
Concerning uCMS, there was an upregulation in claudin-5 protein levels only in females suggesting a possible compensatory mechanism of the BBB in response to a prolonged situation of stress. In conclusion, acute and uCMS induce distinct behavioural and biochemical profiles, particularly affecting BBB proteins.
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