Melatonin in immunity: comparative aspects

Area of Science:

• Neuroendocrinology
• Immunology
• Chronobiology

Background:

• The pineal gland regulates internal homeostasis through melatonin (MEL) synthesis and release, linked to diurnal rhythms.
• Reciprocal interactions between the neuroendocrine and immune systems are crucial for vertebrate homeostasis.
• Melatonin plays a role in both developmental and immune-activated responses.

Purpose of the Study:

• To review experimental data on the interactions between the pineal gland and the immune system in mammals and birds.
• To elucidate the mechanisms by which melatonin influences immune parameters.
• To describe the feedback loop where immune factors signal to the pineal gland.

Main Methods:

• Review of experimental data on pineal gland-immune system interactions.
• Analysis of melatonin's effects on immune cells via membrane and nuclear receptors.
• Examination of immune-derived factors acting on the pineal gland.

Main Results:

• Melatonin (MEL) influences immune cells through various receptors.
• MEL's effects on immunity are dose-dependent and influenced by numerous factors (species, age, immune activation, etc.).
• Immune organ-derived hormones and cytokines act as signals to the pineal gland, completing a regulatory loop.

Conclusions:

• The pineal gland and immune system exhibit complex, bidirectional communication essential for maintaining homeostasis.
• Melatonin's immunomodulatory effects are highly context-dependent.
• A closed regulatory loop exists between the pineal gland and immune system through hormonal and cytokine signaling.