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hpa axis

Environmental Enrichment Reversed Visceral Pain and Depression in Rats

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MHD featured image for environmental enrichment, visceral pain, depression, and CB1 receptor circuitry.

A 2026 Communications Biology rat study found that enriched housing reversed early-life-stress visceral hypersensitivity and depression-like behavior by normalizing a CB1 receptor-linked prefrontal-limbic circuit connecting prelimbic cortex, anteroventral bed nucleus of the stria terminalis, and paraventricular hypothalamus.1 Huang et al. mapped a gut-pain and mood circuit in rats, but the experiment does not prove that …

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Stress Internalization Predicts Memory Decline in Older Chinese Americans

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Editorial card showing an older Chinese American adult and a memory-decline trajectory, illustrating the PINE cohort finding that stress internalization predicts cognitive decline.

A 2025 longitudinal analysis of 1,528 older Chinese Americans by Chen et al. in the Journal of Prevention of Alzheimer’s Disease says something more specific than “stress causes Alzheimer’s”: it isn’t the count of stressors that tracks memory decline — it’s a latent trait the authors call stress internalization, a bundle of high perceived stress, …

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Dexamethasone Disrupts Mouse Sleep Through Orexin Hyperarousal

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Photoreal illustration of a steroid pill bottle with overlay of disrupted sleep architecture, conveying glucocorticoid-induced insomnia mechanism.

A 2026 male-mouse study found that 30 mg/kg dexamethasone for 5 days increased light-phase wakefulness (t13 = 4.122, p = 0.0012), decreased NREM sleep (t13 = 4.412, p = 0.0007), and amplified orexin-neuron activity during NREM-to-wake transitions (F1,9 = 6.941, p = 0.0272). The result points to orexin-linked hyperarousal as a testable explanation for steroid-induced …

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Saffron Extract (Affron) Reduces Stress via HPA Axis & Neuroplasticity in Rats (2023 Study)

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In a world increasingly burdened by the psychological strains of modern living, the quest for effective and safe treatments for stress-related symptoms has never been more urgent. A recent study evaluated the stress-mitigating properties of Affron® – a Saffron extract – in animal models, revealing its potent effects on the body’s stress response systems, including …

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Natural Plant Polysaccharides for Depression: Antidepressant Mechanisms & Effects (2024 Review)

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Depression is a complex mental health disorder that affects millions of people worldwide, presenting a significant challenge for current medical treatments due to various side effects and drug resistances associated with conventional antidepressants. In response, researchers have turned their attention to natural plant polysaccharides, which have shown promising antidepressant effects through diverse mechanisms. This exploration …

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Kappa Opioid Receptors (KORs) vs. Depression & Stress-Related Brain Region Activation (2023 Study)

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Depression, a complex and multifaceted disorder, challenges both individuals and society with its pervasive effects and the limitations of current treatments. Recent research has spotlighted the opioid system, specifically the kappa opioid receptor (KOR), as a potential target for innovative treatments. This focus is grounded in findings that KOR activation influences stress hormone levels and …

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