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The Pineal Gland -also called the epiphysis- looks like a miniature pine cone and is situated in the middle of the brain beneath the two brain halves, surrounded by the ventricles, under the roof of the corpus callosum (cross-beam connecting the 2 brain halves). (see picture) This active organ has, together with the Pituitary Gland (see picture), the next highest blood circulation after the kidneys. It is not protected by the blood-brain barrier and therefore makes this gland fragile to any substance entering the bloodstream. It is, for instance, very sensitive to fluoride.
Another factor involved in affecting the Pineal Gland can be excessive high or even toxic levels of an SSRI-AntiDepressant in the bloodstream. Certain individuals have a metabolic deficiency in the metabolism of anti-depressant medication. In the liver, a group of enzymes named " cytochrome P-450" enzymes, particularly the "CYP2D6 enzymes" of this group of enzymes, metabolise SSRI-AntiDepressants. When not properly metabolised, because one has a metabolic deficiency, a daily therapeutic dose can build up to excessive high or even toxic levels in the bloodstream. Hence, the Pineal Gland would be an easy target, since it is not very well protected by the blood-brain barrier. It is it's connection to serotonin what makes this organ so very interesting.
3.a. The Pineal Gland-Serotonin connection
Nicholas Giarmin, a professor of pharmacology and Daniel Freedman, a professor of psychiatry, confirmed that the human brain manufactures serotonin at various sites in the brain. For example, in the Thalamus, they discovered 61 nanograms of serotonin per gram of tissue; in the Hippocampus, 56 ng.; in the Central Gray Section of the Midbrain, they found 482 ng. But in the Pineal Gland, they found 3140 ng. of serotonin per gram of tissue. The Pineal Gland was unmistakably the richest site of serotonin in the brain! This discovery implicates the Pineal Gland as an important site of serotonergic activity.
The neurohormone Melatonin & the Endocrine System
One of the neurotransmitters secreted by the Pineal Gland is Melatonin, also known as N-Acetyl-5-Methoxy-Tryptamine (NA-5-MT). In the Pineal Gland, serotonin converts into melatonin by enzymatic interaction. Melatonin is also an important hormone to the body, that's why it is called a neurohormone. It is necessary to regulate the function of all organs of the Endocrine System in the body. The organs or glands of the endocrine system are: the Pituitary Gland, situated in the brain; the Thyroid + Parathyroid Glands; the Thymus; the Pancreas; the Ovaries/Testes (see image). All of these endocrine organs/glands secrete their hormones to the blood. The Pituitary Gland stimulates the secretion of these hormones, while the Pineal Gland apply the brakes on them through it's neurohormone melatonin. If the endocrine organs/glands release too much of their hormones, for instance when we are stressed, then the Pineal Gland releases melatonin to counteract these hormones. Also serotonin gets released when stress is involved. The increased serotonin triggers the release of adrenaline, which allows the body to work through the stress.
The Pineal Gland is a magneto sensitive organ, what means that it is sensitive to electromagnetic fields (EMF). It is sensitive to electromagnetic waves from computer monitors, cellular phones, microwave ovens, high voltage lines, etc.. Electromagnetic fields suppress the activity of the Pineal Gland and reduce melatonin production. EMF also affect serotonin.
The neurohormone Melatonin & the Eye-SCN-Pineal Gland Axis
The Pineal Gland is also a photosensitive organ, what means that it is sensitive to light. It normally releases melatonin when it no longer receives light impulses. Just like serotonin, also melatonin has it's own day & night cycle (circadian rhythm) which begins where the cycle of serotonin normally ends. When serotonin reaches it's lowest level at night (in the dark) during slow wave sleep, the Pineal Gland starts to convert it's store of serotonin into melatonin to be released prior to REM sleep. Melatonin has it's peak around 02:00 AM. During daytime, the daylight inhibits the release of melatonin. This works as follows: when, during daytime, light reaches the eyes, then it's presence gets translated into nerve impulses, which travel through the optic nerve between the eyes and a region of the Hypothalamus called the "Suprachiasmatic Nucleus" (SCN). (see picture) The SCN in it's turn sends it's nerve impulses to the Pineal Gland. These impulses inhibit the Pineal Gland's production of melatonin until it gets dark, when it's to be released again. Melatonin is not only present in the brain and body but also in the eye! One has speculated whether or not high melatonin levels in the eyes during daylight exposure, may bring damage to them over time. Visual/eye problems (light sensitivity, spots, blurred vision) are other symptoms, frequently reported by (former) SSRI-AntiDepressant users. I questioned myself if these problems could be related to elevated melatonin levels in the eye. When serotonin accumulates in the Pineal Gland, on account of an SSRI-AntiDepressant, then it would come under pressure to produce more melatonin out of the excessive amounts of serotonin. Hence, during daytime, melatonin levels in the eyes would be significantly higher then normally would occur... But, I had to revise this hypothesis. In a PubMed study, SSRI-AntiDepressants were found not to elevate melatonin levels in humans. Although "Luvox" and "Paxil" increases melatonin to a more or lesser amount, apparently this seemed not to be the case for the other SSRI-AntiDepressants. However, since the Pineal Gland does contain a complete map of the visual field of the eyes, could there be a correlation between visual/eye problems and a dysfunctional Pineal Gland?
A case, noted by Dr. Berman, could give us some more insight into this matter:
A child was brought to a German clinic suffering from eye trouble and headaches. He was five years old and very mature, and apparently had reached the age of adolescence. He was abnormally bright mentally, discussing metaphysical and spiritual subjects. He was strongly group-conscious and only happy when sharing what he had with others. After his arrival at the clinic, he rapidly grew worse and died in a month. An autopsy showed a tumour of the pineal gland. - Berman, Louis, M.D., The Glands Regulating Personality, p. 89. Could it be that the visual/eye problems (light sensitivity, spots, blurred vision), frequently reported by (former) SSRI-AntiDepressant users, are caused by some element of Pineal Gland dysfunction?