The Pineal Gland and the ‘Third Eye’
The pineal organ or gland in the brain has been known about for a very long time. 2500 years ago, the ancient Greek physicians believed that it acted as a ‘valve’ controlling the ‘humours’ as they travelled through the ventricles of the brain. This was taken up by the French philosopher Rene Descartes during the Renaissance. Descartes is famous for his statement that the pineal is the “seat of the soul” (though he wrote that the soul cannot be confined by any part of the body). During most of the 20th century, though, the pineal was thought, by medical science, to be a useless vestige.
In the 1890s a German physician by the name of Heubner descibed several cases of precocious puberty in children whose pineals were damaged by brain tumours. The reason for this became evident many decades later, in the 1970s, when it was established that melatonin from the pineal suppresses the sex hormones (gonadotrophins) Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH), which are secreted by the anterior lobe of the pituitary gland. Damage to the pineal gland by the tumours resulted in increases in FSH and LH, causing the children to develop precocious puberty.
Around the same time as Huebner’s discoveries the Theosophist Helena Blavatsky wrote, in The Secret Doctrine, that the ‘third eye” of Hindu and Buddhist mythology and iconography referred to the pineal, and that this corresponded with the agna or brow chakra. This belief was promoted in the West with the hippie movement of the 1960s and 1970s and again by the New Age Movement in the 1990s.
Interestingly, in the 1960s, during a period of intense research into the gland/organ following the discovery of melatonin in 1958, it was discovered that the pineal is, in fact, connected to the visual system in humans and other mammals, and functions as a light-sensitive third (or parietal) eye in certain reptiles and amphibians. In these animals the pineal is closer to the surface of the skull, rather than deep in the middle of the brain as in humans and other mammals. It was also hypothesised that in birds the pineal functions as a magnetic sense organ, involved in their sense of direction and migrations.
It was also discovered that the pineal has a high blood circulation and complex vasculature. This went against the vestigial theory, which was completely disproved with the discovery that the gland secretes the hormone melatonin and other substances.
Prior to the discovery of melatonin by the dermatologist Aaron Lerner at Yale University in 1958, it was taught, in medical schools and science courses that the pineal is a useless vestigial organ, the primitive remains of the “reptilian brain”. The idea that it had no function in humans was reinforced by the observation that the gland calcifies with age (though not equally in different people). This calcification was named “brain sand” and presented as evidence to support the incorrect vestigial theory.
This all changed in 1958 with the discovery of the chemical structure of melatonin, the main hormone secreted by the pineal. Professor Lerner was looking for a skin-lightening factor in frogs and discovered that the melatonin molecule caused clumping of the pigment granules (chromatophores) in the frog skin. He identified the chemical as an indole amine, synthesised from the dietary amino acid tryptophan via 5-hydroxy tryptamine (5HT), better known these days as serotonin. Studies in the 1960s established that melatonin has no effect on skin pigmentation in humans.
It was discovered that serotonin, which is also produced in other parts of the brain and acts as a neurotransmitter (chemical messenger released from nerve endings) is concentrated in the pineal. Serotonin is also produced in the intestines, but the intestinal serotonin does not cross the blood-brain barrier and enter the brain.
The enzymes involved in the metabolism of serotonin and melatonin were discovered and named in the 1960s, and it was found that synthesis of melatonin, which occurs mainly at night and in darkness, is suppressed by light shone into the eyes in rats and in primates. It was also found that melatonin synthesis from serotonin is modulated by the sympathetic branch of the autonomic nervous system (the so-called flight or fight system) via the neurotransmitter noradrenaline (norepinephrin).
Subsequent research showed the pineal to have effects on a range of pituitary hormones – the 1980 edition of Harrison’s Principles of Internal Medicine described it as a “neuroendocrine transducer” modulating between the nervous system (brain) and endocrine system (hormones). It has also been established that melatonin is a powerful antioxidant (active against free radicals) and also has effects on mood, blood temperature, the immune system (and development of cancer) and sleep. In the 1990s it was marketed as a treatment for jetlag, with the claim that it “reset the body clock” and it was also promoted as a mild sleeping tablet.
It was discovered, in the early 1970s, that the extent of pineal calcification varies geographically. Researchers found that this is much less common in Japan, Africa and India than in the USA or Europe. Noting this, researchers in the 1970s compared pineal calcification in “black” and “white” Americans and found that the “blacks” had significantly less calcification than the “whites”, though the incidence was not as low as in Japan or Africa. This suggests a combination of genetic and environmental factors in pineal calcification.
Pineal calcification had first been described on autopsy specimens 300 years ago, and on X-ray in 1918. Studies, mainly on Caucasians, showed that calcification increased with age – from 2% in children aged 3 to 12, 46% from 13 to 40 and 69% after the age of 40, according to a 974 review by Adelola Adeloye and Benjamin Franklin at the Cincinnati Hospital in Ohio. These researchers reported that others had found much lower incidences in Japan (9.9%), Fiji (15.6%) and India (19-24 %) with even lower incidences reported from Nigeria and West Africa (Nigeria – 5%) and East Africa (Uganda – 2%). Their studies comparing the skull X-rays at of 500 patients seen at the Cincinnati Hospital who were categorised as “black” or “white” showed a statistically significant difference of 1:1.6 in “blacks” and “whites”.
It should be pointed out that pineal calcification does not correlate well with the amount of melatonin that is produced by the gland, though there is a gradual decrease in melatonin production with age.
In recent years there have been efforts to market melatonin as a “nutritional supplement” to extend life. This may not be wise, since as a general principle, taking an exogenous hormone supresses ones natural production of the hormone. This is seen in people who take cortisone or thyroxine, and may also occur with melatonin.
It is also known that melatonin levels are affected by a range of drugs, especially psychiatric drugs (dopamine blockers and antidepressants). The selective serotonin reuptake inhibitor (SSRI) drugs can cause both increase and decrease in melatonin levels. The significance of this to health is uncertain and there is a dearth of studies that expose the negaive effects of drugs generally, due to the funding of the studies and the publications.
The pineal also secretes other chemicals in addition to melatonin. There is still a lot to learn about this fascinating gland,and how to naturally optimise its function.
Dr Romesh Senewiratne-Alagaratnam's Blog 