Interleukin-6 (IL-6) is a cytokine initially identified as a B-cell differentiation factor but has since been found to play crucial roles in various physiological systems, including the nervous system. IL-6 is involved in neurogenesis, neuroinflammation, and the response of neurons and glial cells to injury. It exhibits neurotrophic-like effects and is part of the neuropoietin family, which includes other cytokines that affect hematopoietic and nervous systems. IL-6 signaling involves the recruitment of gp130, a modular protein, and can be activated by trans-signaling through soluble forms of IL-6 receptor (sIL-6R) and gp130 (sgp130). IL-6 expression is regulated by various factors and is upregulated in response to injury and inflammation in the central nervous system (CNS). In normal brain function, IL-6 regulates body weight, food intake, energy expenditure, and other physiological processes. However, in pathological conditions such as stroke, multiple sclerosis, Alzheimer's disease, and Parkinson's disease, IL-6 is often upregulated and can have detrimental effects, contributing to neuroinflammation and neuronal damage. Therapeutic approaches targeting IL-6 aim to modulate its effects to treat these diseases.Interleukin-6 (IL-6) is a cytokine initially identified as a B-cell differentiation factor but has since been found to play crucial roles in various physiological systems, including the nervous system. IL-6 is involved in neurogenesis, neuroinflammation, and the response of neurons and glial cells to injury. It exhibits neurotrophic-like effects and is part of the neuropoietin family, which includes other cytokines that affect hematopoietic and nervous systems. IL-6 signaling involves the recruitment of gp130, a modular protein, and can be activated by trans-signaling through soluble forms of IL-6 receptor (sIL-6R) and gp130 (sgp130). IL-6 expression is regulated by various factors and is upregulated in response to injury and inflammation in the central nervous system (CNS). In normal brain function, IL-6 regulates body weight, food intake, energy expenditure, and other physiological processes. However, in pathological conditions such as stroke, multiple sclerosis, Alzheimer's disease, and Parkinson's disease, IL-6 is often upregulated and can have detrimental effects, contributing to neuroinflammation and neuronal damage. Therapeutic approaches targeting IL-6 aim to modulate its effects to treat these diseases.