The Pineal Gland

The Pineal Gland: "elevating melatonin synthesis in the pinealocytes (Ganguly et al., 2001; Schomerus and Korf 2005). Recent studies have also shown that the removal of the SCN results in a daytime increase in Aa-nat mRNA levels, suggesting that the presence of an inhibitory SCN output contributs to the control of pineal melatonin rhythm (Kalsbeek et al., 2000). It has also been suggested that the GABA-ergic output of the SCN terminals on to the pre-autonomic PVN neurons may be the daytime inhibitory signal contributing to the morning decline of melatonin synthesis (Kalsbeek et al., 2000).

Another important factor in the regulation of the melatonin level is represented by light. Light is the dominant environmental factor that regulates melatonin biosynthesis in vertebrates, and regardless of whether a species is diurnal/nocturnal or exhibits crepuscular activity, pineal melatonin levels are high during the dark phase of a natural or imposed illumination cycle (Reiter, 1991; Arendt, 1999)."

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The Pineal Gland

The Pineal Gland: "Light signals perceived by the retina are conveyed via the retinohypothalamic tract to the SCN, and then to the mammalian pineal gland via the previously mentioned pathway (Korf et al., 1998; Korf, 1999). Light exerts a distinct suppressive effect on melatonin production irrespective of whether it is full spectrum white light, monochromatic light or UV-A light. The amount of light required to suppress melatonin production at night varies with species, previous light exposures, and the particular time of the night (Bojkowski et al., 1987; Brainard et al., 1988, 2001). Blue light (446-477 nm) is the most effective light to suppress melatonin (Brainard et al., 2001), thus suggesting that the intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in this phenomenon (Paul et al., 2009). Another important factor involved in the regulation of melatonin synthesis and levels is age."

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The Pineal Gland

The Pineal Gland: "
The suprachiasmatic nuclei (SCN) of the hypothalamus via a sympathetic multisynaptic pathway regulates rhythmic melatonin synthesis by acting on Aa-nat transcription (Klein et al., 1983; Tessonneaud et al., 1995; Garidou et al., 2002; Perreau-Lenz et al., 2005). The SCN uses a combination of daytime inhibitory and nighttime stimulatory signals to control the daily rhythm of pineal melatonin synthesis (Perreau-Lenz et al., 2003, 2004). At night the sympathetic neurotransmitter, Norepinephrine (NE), is released from the postganglionic nerve terminals innervating the pineal, thus stimulating (ß1 and 1 adrenoreceptors on the pinealocytes, leading to an increase in intracellular calcium levels."

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The Pineal Gland

The Pineal Gland: "Finally, it has also been suggested that melanopsin may mediate the photosensitivity observed in the neonatal pineal (Saafir et al., 2006). The reason why the mammalian pineal has lost the capability to directly respond to light is unknown, but it is believed to be a consequence of the evolutionary history of mammals (Menaker et al., 1997).


Melatonin Synthesis in the Pineal Gland
The pineal hormone melatonin is primarily synthesized in the pineal gland at night regardless of the diurnal or nocturnal activity of the animals. "

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The Pineal Gland

The Pineal Gland: "Introduction
The Pineal Gland (epiphysis cerebri in mammals), conferred as "the seat of Human soul" by Rene Descartes in 17th century,

was considered as an epithalamic appendage of the vertebrate brain, and a vestigial evolutionary element until the 19th century.

http://www.photobiology.info/Tosini.html


 The endocrine aspect of the pineal gland reported in the early 20th century was confirmed through isolation of the hormone melatonin by Aaron B. Lerner in 1958.

The pineal thus attracted scientific attention in the late 20th century due to its crucial role of transducing photoperiodic information through the rhythmic secretion of the daily and annual timekeeping hormone melatonin."

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The Pineal Gland

The Pineal Gland: "Melatonin Synthesis in the Pineal Gland
The pineal hormone melatonin is primarily synthesized in the pineal gland at night regardless of the diurnal or nocturnal activity of the animals. The initial step of the biosynthesis of this indoleamine involves the uptake of its precursor L-tryptophan from the circulation into the pinealocytes, "

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Israeli Minister Agrees Ahmadinejad Never Said Israel 'Must Be Wiped Off the Map' - NYTimes.com

Israeli Minister Agrees Ahmadinejad Never Said Israel 'Must Be Wiped Off the Map' - NYTimes.com: "Those words were attributed to Mr. Ahmadinejad in 2005, in English translations of his speech to a “World Without Zionism” conference that October. As my colleague Ethan Bronner reported the next year, one problem was translating a metaphorical turn of phrase in Persian that has no exact English equivalent — there was, for instance, no mention of a map — and there was a heated debate about whether the original statement was a threat or a prediction."

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