Difference between revisions of "Pineal gland" - New World Encyclopedia

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[[image:Illu_pituitary_pineal_glands.jpg|thumb|300px|Diagram of pituitary and pineal glands.]]
 
[[image:Illu_pituitary_pineal_glands.jpg|thumb|300px|Diagram of pituitary and pineal glands.]]
[[Image:Gray719.png|thumb|300px|[[Gray's Anatomy|Gray's]] FIG. 719– Hind- and mid-brains; postero-lateral view. (Pineal gland near top.)]]
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[[Image:Gray719.png|thumb|300px|Gray's Anatomy FIG. 719—Hind- and mid-brains; postero-lateral view. (Pineal gland near top.)]]
The '''pineal gland''' (also called the '''pineal body''' or '''epiphysis cerebri''' or '''epiphysis''') is a small pine cone-shaped endocrine organ in the brain. It is located in a sinus on the midline where the two cerebral hemispheres meet the cerebellum. It secretes the hormone melatonin in a circadian rhythm with higher levels in the dark and lower levels in the light phase.
+
The '''pineal gland''' (also called the '''pineal body''', '''epiphysis cerebri''', or '''epiphysis''') is a small [[Pine#Cones|pine cone-shaped]] [[endocrine system|endocrine]] organ found in the skull of [[vertebrate]]s. It produces and secretes [[melatonin]] in a [[circadian rhythm]] with higher levels in the dark phase and lower levels in the light phase.
 +
 
 +
The pineal gland appears to be sensitive to small amounts of light that penetrate the skin and skull in some vertebrates or via the retina in [[mammal]]s. It seems to play a role with respect to circadian rhythms and in some aspect of regulating sexual reproduction or sexual development. However, the importance and role of the pineal gland is not clearly understood, and this mystery has historically led to various metaphysical theories. [[Rene Descartes]] called it the "seat of the soul," and others have attributed importance to it in terms of "spiritual vision" or "intuition."
  
 
==Location==
 
==Location==
The pineal gland is a small body about the size of a pea in adult human beings, located just rostro-dorsal to the superior colliculus and behind and beneath the stria medullaris, between the laterally positioned thalamic bodies.It is attached to the roof of the third ventricle and is part of the epithalamus. In human beings it lies deep within the brain ,but in most vertebrates it lies just beneath the skull.
+
The pineal gland is a small body about the size of a [[pea]] in adult [[human]] beings, located just rostro-dorsal to the superior colliculus and behind and beneath the stria medullaris, between the laterally positioned thalamic bodies. It is attached to the roof of the third ventricle and is part of the epithalamus.  
 +
 
 +
In human beings, it lies deep within the [[brain]], but in most [[vertebrate]]s it lies just beneath the skull.
  
The pineal gland is a midline structure, and is often seen in plain skull X-rays, since it is often calcified.
+
The pineal gland is a midline structure, and is often seen in plain skull [[X-ray|X-rays]], since it is often calcified.
  
 
==Structure and composition==
 
==Structure and composition==
The pineal gland consists mainly of pinealocytes, but four other cell types have been identified: interstitial cells, perivascular phagocytes, pineal neurons and peptidergic neuron-like cells.
+
The pineal gland consists mainly of pinealocytes, but four other [[cell (biology)|cell]] types have been identified: interstitial cells, perivascular phagocytes, pineal neurons, and peptidergic [[neuron]]-like cells.
 +
 
 +
The pineal gland in humans consists of a lobular parenchyma of pinealocytes surrounded by connective tissue. The gland's surface is covered by a pial capsule. The pinealocyte consists of a cell body with four to six processes emerging. Insterstitial cells are located between the pinealocytes. Many capillaries are present in the gland and perivascular phagocytes are located close to these blood vessels. The perivascular phagocytes are [[antigen]]-presenting cells. In higher [[vertebrate]]s, neurons are located in the pineal gland, but are absent in [[rodent]]s. In some species, neuronal-like peptidergic cells are present, which might have a paracrine regulatory function.  
  
The pineal gland in humans consists of a lobular parenchyma of pinealocytes surrounded by connective tissue spaces. The gland's surface is covered by a pial capsule. The pinealocyte consists of a cell body with 4-6 processes emerging. Insterstitial cells are located between the pinealocytes. Many capillaries are present in the gland and perivascular phagocytes are located close to these blood vessels. The perivascular phagocytes are antigen-presenting cells. In higher vertebrates neurons are located in the pineal gland,but are absent in rodents. In some species, neuronal-like peptidergic cells are present, which might have a paracrine regulatory function.
+
Human pineal glands contain a variable quantity of gritty material, called brain sand. Chemical analysis of this sand shows that it is composed of calcium phosphate, calcium carbonate, magnesium phosphate, and ammonium phosphate (Bocchi et al. 1993).
Human pineal glands contain a variable quantity of gritty material, called brain sand. Chemical analysis of this sand shows that it is composed of calcium phosphate, calcium carbonate, magnesium phosphate, and ammonium phosphate. (Bocchi ''et al.''  1993). Recently, calcite deposits have been described as well (Baconnier ''et al''. 2002).
 
  
 
==Function==
 
==Function==
The pineal gland was originally believed to be a vestigial remnant of a larger organ. In 1960 Dr. Lerner discovered that the pineal gland is responsible for the production of melatonin, which is produced in a circadian rhythm. When the retina detects light, a signal is sent to the the suprachiasmatic nucleus (SCN). Fibers travel from the SCN to the paraventricular nuclei (PVN), which relay the signal to the spinal cord  and then out via the preganglionics of the sympathetic nervous system .The preganglionic cells travel to the superior cervical ganglia where they synapse upon postganglionic fibers which travel to the pineal gland.
+
The pineal gland was originally believed to be a "vestigial remnant" of a larger organ. In 1960 Lerner and Takahashi reported that the pineal gland contained a unique compound, known as melatonin. It was later found to be synthesized in a [[circadian rhythm]], with larger amounts being produced in the dark phase.
  
The pineal gland is larger in children, but shrinks at puberty. It may play a  role in human sexual development. The higher melatonin levels in children may inhibit sexual development. Pineal tumors have in some cases been linked to precocious puberty. When puberty arrives, melatonin production is reduced. However, the absence of a pineal gland in humans does not always have the same effect on sexual development.
+
In cyclostomes, [[fish]], [[amphibian]]s, [[reptile]]s, and [[bird]]s, the pineal body appears to be directly sensitive to small amounts of light that penetrate the skin and skull. In [[mammal]]s, with increased development of the cerebral hemispheres, the pineal body came to lie deeper within the brain and indirect stimulation of the pineal gland by light via the [[eye|retina]] came to be more important. When the retina detects light, it sends a signal through the optic nerve to the the suprachiasmatic nucleus (SCN) within the hypothalamus. Fibers travel from the SCN to the paraventricular nuclei (PVN), which relay the signal to the spinal cord and then out via the preganglionic fibers of the sympathetic [[nervous system]]. The preganglionic cells extend to the superior cervical ganglia where they synapse upon postganglionic fibers, which in turn terminate on the pineal gland.
  
Removal of the pineal gland in rats results in hypertrophy of the anterior pituitary, the ovaries and the adrenals(Wurtman ''et al''. 1959 ).
+
The pineal gland may play a role in human sexual development. The higher melatonin levels in children may inhibit sexual development. Pineal tumors have in some cases been linked to precocious puberty. With increasing age, melatonin production is reduced and calcification is increased. However, the absence of a pineal gland in human beings does not have a consistent effect on sexual development.
  
In male hamsters the testes become small in the winter,when the nights are longer, and increase in the spring,when the nights are shorter. When the pineal organ is removed , these organs do not atrophy in the winter (Reiter 1973).
+
Removal of the pineal gland in rats results in hypertrophy of the anterior [[pituitary]], the ovaries, and the [[adrenal gland|adrenals]] (Wurtman et al. 1959). The pineal gland is often referred to as antigonadotrophic and appears to inhibit the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary.
  
Pinealocytes in lower vertebrates have a strong resemblance to the photoreceptor cells of the eye. Some evolutionary biologists believe that the vertebrate pineal gland can be traced to a proto-eye structure in early vertebrate organisms (Klein 2004). Modern [[bird]]s and [[reptile]]s have been found to express the phototransducing pigment melanopsin in the pineal gland. Avian pineal glands are believed to act like the SCN in [[mammal]]s (Natesan ''et al''. 2002).
+
The pineal gland appears to play a role in seasonal breeders, like hamsters. The testes normally become smaller and less active in the winter, when the nights are longer, and become larger and more active in the spring, when the nights are shorter. When the pineal organ is removed, these organs do not atrophy in the winter (Reiter 1973). Thus, the pineal gland seems to be important in providing information not only as a circadian clock but also as a seasonal clock to regulate sexual reproduction.
  
In lower  vertebrates, the pineal gland is located on the surface of the brain, directly under the skull, and contains photoreceptor-like structures that may regulate their biological clock ( Moore ''et al.'' 1967). In humans and other mammals, this function is served by the retinohypothalamic system that sets the rhythm within the suprachiasmatic nucleus. Cultural and social interactions produce exposures to artificial light that influence the setting of the suprachiasmatic clock. Evidence for a role of opsin-related light-sensing compounds in the skin of mammals is presently controversial.  
+
Avian pineal glands are believed to contain a circadian clock that acts much like the SCN of the hypothalamus does in [[mammal]]s (Natesan et al. 2002). Their pinealocytes are photosensitive and contain melanopsin as well as a unique pigment called pinopsin (Okano et al. 2002).
 
   
 
   
 +
In lower vertebrates, the pineal gland is located on the surface of the brain, directly under the skull, and contains photoreceptor-like structures that may regulate their biological clock (Moore et al. 1967). These structures bear a strong resemblance to the photoreceptor cells of the [[eye]]. Some evolutionary biologists believe that the vertebrate pineal gland can be traced to a proto-eye structure in early vertebrate organisms (Klein 2004).
 +
 +
The pineal gland may offer protection against the actions of drugs of abuse, such as [[cocaine]] (Uz et al. 2003) and antidepressants, such as Prozac (Uz et al. 2004), and contribute to the regulation of neuronal vulnerability (Manev et al. 1996).
  
Reports in rodents suggest that the pineal gland may offer protection against the actions of drugs of abuse such as cocaine [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12865893&query_hl=49] and antidepressants such as fluoxetine (Prozac)[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15094477&query_hl=49]; and contribute to regulation of neuronal vulnerability[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8940301&query_hl=55].
+
A tremendous amount of research has been done on the pineal organ. Most of the research has centered on the role of the pineal organ in maintaining circadian rhythms. However, much of it has yielded inconsistent results. The importance of the pineal body and its functional role(s) in vertebrates is not yet understood clearly (Macchi 2004).
  
 
==Metaphysics and the pineal==
 
==Metaphysics and the pineal==
The pineal gland was the last endocrine gland to have its function discovered. This combination led to its being a "mystery" gland with myth, superstition and even metaphysical theories surrounding its perceived function.
+
The pineal gland was the last endocrine gland to have its function discovered. This combination led to its being a "mystery" gland with myth, superstition, and even metaphysical theories surrounding its perceived function.
  
[[Rene Descartes]],in the seventeenth century, called the pineal gland the "seat of the soul" .
+
[[Rene Descartes]], in the seventeenth century, called the pineal gland the "seat of the soul." The pineal gland is occasionally associated with the sixth chakra (also called Ajna or the third eye chakra in [[yoga]]). It is believed by some to be a dormant organ that can be awakened to enable "telepathic" communication. Madame Blavatsky (1888) called the pineal body the "eye of Shiva" and said that in modern man it is a vestigial "organ of spiritual vision." Believers in Discordianism feel that the pineal body is involved in intuition.
The pineal gland is occasionally associated with the sixth chakra (also called Ajna or the third eye chakra in yoga). It is believed by some to be a dormant organ that can be awakened to enable "telepathic" communication. Madame Blavatsky called the pineal body the "eye of Shiva" and said that in modern man it is a vestigial "organ of spiritual vision". Believers in Discordianism feel that the pineal body is involved in intuition.
 
  
 
==References==
 
==References==
 
+
* Blavatsky, H. P. 1888. ''The Secret Doctrine'', vol. II. Theosophical University Press Online Edition, pp. 289-306.[[http://www.theosociety.org/pasadena/sd/sd2-1-17.htm]]
*Baconnier,S.,S.B.Lang,M.Polomska,B.Hilczer,G.Berkovic,G.Meshulam.2002.Calcite microcrystals in the pineal gland of the human brain:first physical and chemical studies.''Bioelectromagnetics''(7):488-495.[[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12224052&query_hl=1&itool=pubmed_docsum]]
+
* Bocchi, G., and G. Valdre. 1993. Physical, chemical, and mineralogical characterization of carbonate-hydroxyapatite concretions of the human pineal gland. ''Journal Inorganic Biochemistry'' 49 (3): 209-220.[[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8381851&query_hl=1&itool=pubmed_docsum]]
 
+
* Descartes, Rene. ''Treatise of Man''. New York: Prometheus Books, 2003. ISBN 1591020905
*Blavatsky,H.P. 1888. ''The Secret Doctrine'',vol. II,pp.289-306.[[http://www.theosociety.org/pasadena/sd/sd2-1-17.htm]]
+
* Klein, D. C. 2004. “The 2004 Aschoff/Pittendrigh Lecture: Theory of the origin of the pineal gland—a tale of conflict and resolution.''Journal of Biological Rhythms'' 19 (4): 264-279. [[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15245646&query_hl=7&itool=pubmed_docsum]]
 
+
* Lerner, A. B. and Y. Takahashi. 1960. “Isolation of melatonin and 5-methoxyindole-3-acetic acid from bovine pineal glands.” ''Journal of Biological Chemistry'' 235: 1992-1997.
*Bocchi,G.,and G.Valdre. 1993.Physical,chemical,and mineralogical characterization of carbonate-hydroxyapatite concretions of the human pineal gland.''Journal Inorganic Biochemistry''49(3):209-220.[[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8381851&query_hl=1&itool=pubmed_docsum]]
+
* Macchi, M. M. and J. N Bruce. 2004. “Human pineal physiology and the functional significance of melatonin.''Neuroendocrinology'' 25 (3-4):177-195.
 
+
* Manev, H., T. Uz , A. Kharlamov, and J.Y. Joo. 1996. “Increased brain damage after stroke or excitotoxic seizures in melatonin-deficient rats.” ''FASEB Journal'' 10 (13): 1546-1551.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8940301&query_hl=55]
*Descartes,R. 2003 .''Treatise of Man''. New York: Prometheus Books; ISBN 1-59102-090-5
+
* Moore, R. Y., A. Heller, R. J. Wurtman, and J. Axelrod. 1967. “Visual pathway mediating pineal response to environmental light.''Science'' 155 (759): 220–223. PMID 6015532
 
+
* Natesan, A., L.Geetha, and M. Zatz. 2002. “Rhythm and soul in the avian pineal.''Cell Tissue Research'' 309 (1): 35-45.[[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12111535&query_hl=12&itool=pubmed_docsum]]
*Klein,D.C. 2004.The 2004 Aschoff/Pittendrigh lecture:Theory of the origin of the pineal gland - a tale of conflict and resolution. ''Journal of Biological Rhythms'' 19(4):264-279.[[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15245646&query_hl=7&itool=pubmed_docsum]]
+
* Okano, T., T.Yoshizawa, and Y. Fukada. 2002. “Pinopsin is a chicken pineal photoreceptive molecule.” ''Nature'' 372: 94-97.
 
+
* Reiter, R. J. 1973. “Pineal control of a seasonal reproductive rhythm in male golden hamsters exposed to natural daylight and temperature.''Endocrinology'' 92: 423-430.
*Macchi,M.M.,and J.N Bruce. 2004. Human pineal physiology and the functional significance of melatonin. ''Neuroendocrinology'' 25(3-4):177-195.
+
* Uz T., M. Akhisaroglu, R. Ahmed, and H. Manev. 2003. “The pineal gland is critical for circadian period expression in the striatum and for circadian cocaine sensitization in mice.''Neuropsychopharmacology'' 12: 2117-2123.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12865893&query_hl=49]
 
+
* Uz T., N. Dimitrijevic, M. Akhisaroglu, M. Imbesi, M. Kurtuncu, and H. Manev. 2004. “The pineal gland and anxiogenic-like action of fluoxetine in mice.” ''Neuroreport.'' 15 (4): 691-694. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15094477&query_hl=49]
*Moore,R.Y.,A. Heller ,R.J. Wurtman ,J. Axelrod. 1967. Visual pathway mediating pineal response to environmental light. ''Science'' 155(759):220–223. PMID 6015532.
+
* Wurtman, R. J., M. D. Altschule, and U. Holmgren. 1959. “Effects of pinealectomy and of a pineal extract in rats.” ''American Journal of Physiology'' 197: 108-110.
 
 
*Natesan,A.,L.Geetha,and M.Zatz. 2002.Rhythm and soul in the avian pineal. ''Cell Tissue Research'' 309(1):35-45.[[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12111535&query_hl=12&itool=pubmed_docsum]].
 
 
 
*Reiter,R.J. 1973.Pineal control of a seasonal reproductive rhythm in male golden hamsters exposed to natural daylight and temperature. ''Endocrinology'' 92:423-430.
 
 
 
*Wurtman,R.J.,M.D. Altschule, and U.Holmgren. 1959. Effects of Pinealectomy and of a pineal extract in rats.''American Journal of Physiology'' 197:108-110.
 
 
 
==External links==
 
* [http://brainmaps.org High-Resolution Cytoarchitectural Primate Brain Atlases]
 
* [http://braininfo.rprc.washington.edu/Scripts/hiercentraldirectory.aspx?ID=280&toback=0 See more images and get more information from BrainInfo]
 
{{Diencephalon}}
 
 
 
  
 
{{credit|76304411}}
 
{{credit|76304411}}
  
[[Category: Life sciences]]
+
[[Category:Life sciences]]
 +
[[Category:Anatomy and physiology]]

Latest revision as of 00:06, 4 April 2008

Diagram of pituitary and pineal glands.
Gray's Anatomy FIG. 719—Hind- and mid-brains; postero-lateral view. (Pineal gland near top.)

The pineal gland (also called the pineal body, epiphysis cerebri, or epiphysis) is a small pine cone-shaped endocrine organ found in the skull of vertebrates. It produces and secretes melatonin in a circadian rhythm with higher levels in the dark phase and lower levels in the light phase.

The pineal gland appears to be sensitive to small amounts of light that penetrate the skin and skull in some vertebrates or via the retina in mammals. It seems to play a role with respect to circadian rhythms and in some aspect of regulating sexual reproduction or sexual development. However, the importance and role of the pineal gland is not clearly understood, and this mystery has historically led to various metaphysical theories. Rene Descartes called it the "seat of the soul," and others have attributed importance to it in terms of "spiritual vision" or "intuition."

Location

The pineal gland is a small body about the size of a pea in adult human beings, located just rostro-dorsal to the superior colliculus and behind and beneath the stria medullaris, between the laterally positioned thalamic bodies. It is attached to the roof of the third ventricle and is part of the epithalamus.

In human beings, it lies deep within the brain, but in most vertebrates it lies just beneath the skull.

The pineal gland is a midline structure, and is often seen in plain skull X-rays, since it is often calcified.

Structure and composition

The pineal gland consists mainly of pinealocytes, but four other cell types have been identified: interstitial cells, perivascular phagocytes, pineal neurons, and peptidergic neuron-like cells.

The pineal gland in humans consists of a lobular parenchyma of pinealocytes surrounded by connective tissue. The gland's surface is covered by a pial capsule. The pinealocyte consists of a cell body with four to six processes emerging. Insterstitial cells are located between the pinealocytes. Many capillaries are present in the gland and perivascular phagocytes are located close to these blood vessels. The perivascular phagocytes are antigen-presenting cells. In higher vertebrates, neurons are located in the pineal gland, but are absent in rodents. In some species, neuronal-like peptidergic cells are present, which might have a paracrine regulatory function.

Human pineal glands contain a variable quantity of gritty material, called brain sand. Chemical analysis of this sand shows that it is composed of calcium phosphate, calcium carbonate, magnesium phosphate, and ammonium phosphate (Bocchi et al. 1993).

Function

The pineal gland was originally believed to be a "vestigial remnant" of a larger organ. In 1960 Lerner and Takahashi reported that the pineal gland contained a unique compound, known as melatonin. It was later found to be synthesized in a circadian rhythm, with larger amounts being produced in the dark phase.

In cyclostomes, fish, amphibians, reptiles, and birds, the pineal body appears to be directly sensitive to small amounts of light that penetrate the skin and skull. In mammals, with increased development of the cerebral hemispheres, the pineal body came to lie deeper within the brain and indirect stimulation of the pineal gland by light via the retina came to be more important. When the retina detects light, it sends a signal through the optic nerve to the the suprachiasmatic nucleus (SCN) within the hypothalamus. Fibers travel from the SCN to the paraventricular nuclei (PVN), which relay the signal to the spinal cord and then out via the preganglionic fibers of the sympathetic nervous system. The preganglionic cells extend to the superior cervical ganglia where they synapse upon postganglionic fibers, which in turn terminate on the pineal gland.

The pineal gland may play a role in human sexual development. The higher melatonin levels in children may inhibit sexual development. Pineal tumors have in some cases been linked to precocious puberty. With increasing age, melatonin production is reduced and calcification is increased. However, the absence of a pineal gland in human beings does not have a consistent effect on sexual development.

Removal of the pineal gland in rats results in hypertrophy of the anterior pituitary, the ovaries, and the adrenals (Wurtman et al. 1959). The pineal gland is often referred to as antigonadotrophic and appears to inhibit the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary.

The pineal gland appears to play a role in seasonal breeders, like hamsters. The testes normally become smaller and less active in the winter, when the nights are longer, and become larger and more active in the spring, when the nights are shorter. When the pineal organ is removed, these organs do not atrophy in the winter (Reiter 1973). Thus, the pineal gland seems to be important in providing information not only as a circadian clock but also as a seasonal clock to regulate sexual reproduction.

Avian pineal glands are believed to contain a circadian clock that acts much like the SCN of the hypothalamus does in mammals (Natesan et al. 2002). Their pinealocytes are photosensitive and contain melanopsin as well as a unique pigment called pinopsin (Okano et al. 2002).

In lower vertebrates, the pineal gland is located on the surface of the brain, directly under the skull, and contains photoreceptor-like structures that may regulate their biological clock (Moore et al. 1967). These structures bear a strong resemblance to the photoreceptor cells of the eye. Some evolutionary biologists believe that the vertebrate pineal gland can be traced to a proto-eye structure in early vertebrate organisms (Klein 2004).

The pineal gland may offer protection against the actions of drugs of abuse, such as cocaine (Uz et al. 2003) and antidepressants, such as Prozac (Uz et al. 2004), and contribute to the regulation of neuronal vulnerability (Manev et al. 1996).

A tremendous amount of research has been done on the pineal organ. Most of the research has centered on the role of the pineal organ in maintaining circadian rhythms. However, much of it has yielded inconsistent results. The importance of the pineal body and its functional role(s) in vertebrates is not yet understood clearly (Macchi 2004).

Metaphysics and the pineal

The pineal gland was the last endocrine gland to have its function discovered. This combination led to its being a "mystery" gland with myth, superstition, and even metaphysical theories surrounding its perceived function.

Rene Descartes, in the seventeenth century, called the pineal gland the "seat of the soul." The pineal gland is occasionally associated with the sixth chakra (also called Ajna or the third eye chakra in yoga). It is believed by some to be a dormant organ that can be awakened to enable "telepathic" communication. Madame Blavatsky (1888) called the pineal body the "eye of Shiva" and said that in modern man it is a vestigial "organ of spiritual vision." Believers in Discordianism feel that the pineal body is involved in intuition.

References
ISBN links support NWE through referral fees

  • Blavatsky, H. P. 1888. The Secret Doctrine, vol. II. Theosophical University Press Online Edition, pp. 289-306.[[1]]
  • Bocchi, G., and G. Valdre. 1993. Physical, chemical, and mineralogical characterization of carbonate-hydroxyapatite concretions of the human pineal gland. Journal Inorganic Biochemistry 49 (3): 209-220.[[2]]
  • Descartes, Rene. Treatise of Man. New York: Prometheus Books, 2003. ISBN 1591020905
  • Klein, D. C. 2004. “The 2004 Aschoff/Pittendrigh Lecture: Theory of the origin of the pineal gland—a tale of conflict and resolution.” Journal of Biological Rhythms 19 (4): 264-279. [[3]]
  • Lerner, A. B. and Y. Takahashi. 1960. “Isolation of melatonin and 5-methoxyindole-3-acetic acid from bovine pineal glands.” Journal of Biological Chemistry 235: 1992-1997.
  • Macchi, M. M. and J. N Bruce. 2004. “Human pineal physiology and the functional significance of melatonin.” Neuroendocrinology 25 (3-4):177-195.
  • Manev, H., T. Uz , A. Kharlamov, and J.Y. Joo. 1996. “Increased brain damage after stroke or excitotoxic seizures in melatonin-deficient rats.” FASEB Journal 10 (13): 1546-1551.[4]
  • Moore, R. Y., A. Heller, R. J. Wurtman, and J. Axelrod. 1967. “Visual pathway mediating pineal response to environmental light.” Science 155 (759): 220–223. PMID 6015532
  • Natesan, A., L.Geetha, and M. Zatz. 2002. “Rhythm and soul in the avian pineal.” Cell Tissue Research 309 (1): 35-45.[[5]]
  • Okano, T., T.Yoshizawa, and Y. Fukada. 2002. “Pinopsin is a chicken pineal photoreceptive molecule.” Nature 372: 94-97.
  • Reiter, R. J. 1973. “Pineal control of a seasonal reproductive rhythm in male golden hamsters exposed to natural daylight and temperature.” Endocrinology 92: 423-430.
  • Uz T., M. Akhisaroglu, R. Ahmed, and H. Manev. 2003. “The pineal gland is critical for circadian period expression in the striatum and for circadian cocaine sensitization in mice.” Neuropsychopharmacology 12: 2117-2123.[6]
  • Uz T., N. Dimitrijevic, M. Akhisaroglu, M. Imbesi, M. Kurtuncu, and H. Manev. 2004. “The pineal gland and anxiogenic-like action of fluoxetine in mice.” Neuroreport. 15 (4): 691-694. [7]
  • Wurtman, R. J., M. D. Altschule, and U. Holmgren. 1959. “Effects of pinealectomy and of a pineal extract in rats.” American Journal of Physiology 197: 108-110.

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