Pine Cones, Sleep, and Inflammation
The effect of the pineal gland on the inflammatory response.
The pineal gland is a endocrine gland found dorsally to the cerebrum, proximally to the brain stem. It is a small, nodular gland often described as having appearance of a pine cone, hence its herbaceous nomenclature. The pineal gland is a relative of the retina of the eye, evident by its reliance upon the light and dark cycles of the external environment.
The primary secretion of the pineal gland is melatonin, a hormone known to exert its effect upon the inflammatory response, as well as sleep cycles, via the circadian rhythm (ref. Melatonin has been proved to inhibit local inflammatory swelling, accumulation of protein rich fluid around the lungs, macrophage accumulation and tissue damage. Basal levels of melatonin are required for effective antibody production, and is therefore necessary for specific immune responses (ref.
Melatonin is synthesised from serotonin, another prominent hormone found in brain tissue. Serotonin is converted to melatonin via a series of enzymes within the pineal gland. Once melatonin is produced it is released immediately into the surrounding tissues and the bloodstream, without being stored.
Melatonin also functions as a free radical scavenger, further protecting the body from cellular damage from these highly reactive chemical species. It is also hypothesised that melanin may stimulate anti-oxidant enzymes within the cells, cascading the anti-oxidant effect of melatonin. Free radical chemicals can damage DNA as well as interfering with other vital cellular processes, leading to cellular death, or necrosis. Necrosis is not only a symptom of local inflammation, but may also promote further inflammation via the accumulation of inflammation markers and the attraction of inflammatory cells. Damage to the DNA of cells can also have a carcinogenic effect, therefore the inhibition of free radical chemicals by the melatonin is a preventative measure against cancer (ref. The presence of free radical chemicals within the body also promotes aging, hence the production of melatonin also exhibits some age inhibiting effects.
Function of the pineal gland is regulated by external light and dark cycles detected by the eye relayed to the gland via a specialised nervous system connecting the pineal gland to the retina (ref. This nervous stimulation is required for appropriate pineal function, ie. there must be neuronal signals of an external light dark cycle for the pineal gland to release melatonin effectively.
Due to the multitude of effects enabled by the production and secretion of melatonin, the pineal gland can exert anti-inflammatory control over both the innate and specific immune responses.