Terpenes as Potential Multi-Target Modulators of Chronic Stress-Induced Neuroendocrine-Immune Dysregulation

Chronic stress is increasingly recognized as a major contributor to systemic disease. Prolonged or repeated activation of the hypothalamic-pituitary-adrenal (HPA) axis and sympathoadrenal systems may contribute to glucocorticoid receptor resistance and chronic low-grade inflammation, although stress-related responses vary depending on stressor characteristics, population, age, sex, health status, and study design. Elevated levels of pro-inflammatory cytokines (IL-6, IL-1β, TNF-α), oxidative stress, and NF-κB activation contribute to immune dysfunction, neuroinflammation, metabolic disturbances, reproductive and endocrine imbalance, as well as structural and functional alterations in stress-sensitive brain regions. Prolonged exposure to stress may contribute to the development of neuropsychiatric, cardiovascular, metabolic, neurodegenerative, and malignant diseases, highlighting the need for effective strategies to mitigate the detrimental consequences of chronic stress. Given the limitations and adverse effects associated with conventional pharmacological approaches, increasing attention has been directed toward natural bioactive compounds. Terpenes represent a diverse class of phytochemicals with reported anti-inflammatory, antioxidant, and neuromodulatory properties. Terpenes such as limonene and β-caryophyllene, as well as terpenoids such as linalool, may modulate NF-κB, MAPK, and Nrf2 signaling pathways and interact with the endocannabinoid system, thereby attenuating neuroinflammation, oxidative stress, and stress-induced immune dysregulation. This review summarizes current evidence regarding the mechanisms linking chronic stress, HPA axis dysfunction, and systemic disease, with particular emphasis on endocrine, immune, and nervous system alterations. In addition, it critically evaluates the mechanistic and translational potential of terpenes as possible indirect neuroimmune and redox modulators of stress-related pathophysiology.