Neuropeptide Y in the Adult and Fetal Human Pineal Gland

Neuropeptide Y was isolated from the porcine brain in 1982 and shown to be colocalized with noradrenaline in sympathetic nerve terminals. The peptide has been demonstrated to be present in sympathetic nerve fibers innervating the pineal gland in many mammalian species. In this investigation, we show by use of immunohistochemistry that neuropeptide Y is present in nerve fibers of the adult human pineal gland. The fibers are classical neuropeptidergic fibers endowed with largeboutons en passageand primarily located in a perifollicular position with some fibers entering the pineal parenchyma inside the follicle. The distance from the immunoreactive terminals to the pinealocytes indicates a modulatory function of neuropeptide Y for pineal physiology. Some of the immunoreactive fibers might originate from neurons located in the brain and be a part of the central innervation of the pineal gland. In a series of human fetuses, neuropeptide Y-containing nerve fibers was present and could be detected as early as in the pineal of four- to five-month-old fetuses. This early innervation of the human pineal is different from most rodents, where the innervation starts postnatally.

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Neuropeptide Y as a presynaptic modulator of norepinephrine release from the sympathetic nerve fibers in the pig pineal gland

Polish Journal of Veterinary Sciences ◽

10.1515/pjvs-2015-0007 ◽

2015 ◽

Vol 18 (1) ◽

pp. 53-61 ◽

Cited By ~ 1

Author(s):

N. Ziółkowska ◽

B. Lewczuk ◽

B. Przybylska-Gornowicz

Keyword(s):

Pineal Gland ◽

Neuropeptide Y ◽

Sympathetic Nerve ◽

Nerve Fibers ◽

Adrenergic Nerve ◽

Sympathetic Nerve Fibers ◽

Uk 14,304 ◽

Mammalian Pineal Gland ◽

Pharmacologically Active

Abstract Norepinephrine (NE) released from the sympathetic nerve endings is the main neurotransmitter controlling melatonin synthesis in the mammalian pineal gland. Although neuropeptide Y (NPY) co-exists with NE in the pineal sympathetic nerve fibers it also occurs in a population of non-adrenergic nerve fibers located in this gland. The role of NPY in pineal physiology is still enigmatic. The present study characterizes the effect of NPY on the depolarization-evoked 3H-NE release from the pig pineal explants. The explants of the pig pineal gland were loaded with 3H-NE in the presence of pargyline and superfused with Tyrode medium. They were exposed twice to the modified Tyrode medium containing 60 mM of K+ to evoke the 3H-NE release via depolarization. NPY, specific agonists of Y1- and Y2-receptors and pharmacologically active ligands of α2-adrenoceptors were added to the medium before and during the second depolarization. The radioactivity was measured in medium fractions collected every 2 minutes during the superfusion. NPY (0.1 – 10 μM) significantly decreased the depolarization-induced 3H-NE release. Similar effect was observed after the treatment with Y2-agonist: NPY13-36, but not with Y1-agonist: [Leu31, Pro34]-NPY. The tritium overflow was lower in the explants exposed to the 5 μM NPY and 1 μM rauwolscine than to rauwolscine only. The effects of 5 μM NPY and 0.05 μM UK 14,304 on the depolarization-evoked 3H-NE release were additive. The results show that NPY is involved in the regulation of NE release from the sympathetic terminals in the pig pineal gland, inhibiting this process via Y2-receptors.

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Immunohistochemical Studies on Sympathetic and Non-sympathetic Nerve Fibers and Neuronal Cell Bodies in the Pineal Gland of Cotton Rats, Sigmodon hispidus.

Archives of Histology and Cytology ◽

10.1679/aohc.57.47 ◽

1994 ◽

Vol 57 (1) ◽

pp. 47-58 ◽

Cited By ~ 17

Author(s):

Yuko SAKAI ◽

Yoshiki HIRA ◽

Yukio OOMORI ◽

Shigeo DAIKOKU ◽

Shoji MATSUSHIMA

Keyword(s):

Pineal Gland ◽

Sympathetic Nerve ◽

Neuronal Cell ◽

Nerve Fibers ◽

Sigmodon Hispidus ◽

Sympathetic Nerve Fibers ◽

Neuronal Cell Bodies ◽

Cotton Rats ◽

Immunohistochemical Studies

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Study on the projection route of the total length of the sympathetic nerve fibers innervating the rat pineal gland

Neuroscience Research Supplements ◽

10.1016/0921-8696(87)90070-3 ◽

1987 ◽

Vol 5 ◽

pp. S26 ◽

Cited By ~ 1

Author(s):

Yoshiaki Nojyo ◽

Nobuaki Tamamaki ◽

Noriyuki Honda ◽

Tadao Matsuura

Keyword(s):

Pineal Gland ◽

Sympathetic Nerve ◽

Nerve Fibers ◽

Total Length ◽

Sympathetic Nerve Fibers ◽

Rat Pineal Gland

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QUANTITATIVE MICROFLUORIMETRIC STUDIES ON FORMALDEHYDE-INDUCED FLUORESCENCE OF 5-HYDROXYTRYPTAMINE IN THE PINEAL GLAND OF THE RAT

Journal of Histochemistry & Cytochemistry ◽

10.1177/22.10.967 ◽

1974 ◽

Vol 22 (10) ◽

pp. 967-975 ◽

Cited By ~ 29

Author(s):

F. J. H. TILDERS ◽

J. S. PLOEM ◽

P. G. SMELIK

Keyword(s):

Pineal Gland ◽

Sympathetic Nerve ◽

Emission Spectra ◽

Nerve Fibers ◽

Quantitative Parameter ◽

Sympathetic Nerve Fibers ◽

Fluorescence Measurements ◽

Protein Model ◽

The Difference ◽

The Relationship

The formaldehyde-induced fluorescence (FIF) of pineal sections of the rat was measured quantitatively under instrumental conditions causing minimal photodecomposition. Fluorescence measurements on different sections of one pineal gland showed only little variation. Also the difference between animal variation was small, which enabled us to use groups of five to six animals for appropriate determinations. The similarity in emission spectra obtained from the pineal gland and a 5-hydroxytryptamine (5-HT)-containing protein model and the results of pharmacologic specificity tests indicated that pineal FIF is derived from 5-HT. Pineal 5-HT seemed to be stored in two compartments: the pinealocytes and the sympathetic nerve fibers. Reserpine, a drug depleting the neuronal 5-HT pool selectively, induced about 30% decrease in chemically detectable 5-HT content, indicating that 30% of total pineal 5-HT content was stored in the nerve fibers, and 70% was stored in the pinealocytes. FIF was not affected by reserpine, suggesting that FIF measurements were largely independent of the neuronal 5-HT store. The relationship between pineal FIF and chemically detectable 5-HT content was investigated in groups of rats treated with drugs increasing or decreasing pineal 5-HT content. From each group, five pineal glands were prepared for microfluorimetrical studies; the remaining pineal glands were used for chemical determinations of 5-HT and protein content. The linearity of this relationship demonstrated that concentration-dependent quenching did not occur in the fluorescence measured. Therefore it was concluded that FIF might be used as a quantitative parameter for 5-HT stored in the pinealocytes.

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