Intimate associations between the neuropeptide Y system and the galanin-immunoreactive neurons in the human diencephalon

Abstract Galanin and neuropeptide Y (NPY) are among the most abundant neuropeptides in the hypothalamus. The role of NPY and galanin in the regulation of the secretory activity of the anterior pituitary has been well established. In addition, the two peptides interact with a number of neurons synthe...

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Bibliographic Details
Published in:Neuroscience 2010-10, Vol.170 (3), p.839-845
Main Authors: Merchenthaler, I, Rotoli, G, Grignol, G, Dudas, B
Format: Article
Language:English
Subjects:
Aged
Arcuate nucleus
diencephalon
Diencephalon - anatomy & histology
Diencephalon - metabolism
Female
galanin
Galanin - metabolism
Humans
hypothalamo-hypophyseal axis
hypothalamus
immunohistochemistry
Male
Middle Aged
Neurology
Neurons - cytology
Neurons - metabolism
Neuropeptide Y - metabolism
NPY
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Summary:Abstract Galanin and neuropeptide Y (NPY) are among the most abundant neuropeptides in the hypothalamus. The role of NPY and galanin in the regulation of the secretory activity of the anterior pituitary has been well established. In addition, the two peptides interact with a number of neurons synthesizing the releasing and inhibiting hormones and a large number of other neuropeptides. The aim of the present studies was to explore if, as in rodents, NPY innervates galanin-immunoreactive (IR) neurons in the human diencephalon. Due to the long post mortem period and subsequent lack of optimal preservation of the cell membranes in the brain, electron microscopy could not be employed to show the presence of NPY-IR synapses on galanin-IR neurons. Therefore, we used light microscopic double label immunocytochemistry and high magnification microscopy with oil immersion to identify putative juxtapositions between NPY and galanin. Our studies show that similarly to rats, numerous NPY-IR nerve terminals surrounded galanin-IR neurons in the human hypothalamus. Among the hypothalamic regions, the infundibulum (infundibular or arcuate nucleus) contained the largest number of galanin-IR neurons heavily surrounded with NPY-IR nerve terminals. These en passant -type intimate associations between NPY-IR and galanin-IR neuronal elements may be functional synapses and may provide the morphological basis for the NPY-mediated galanin release. Consequently, NPY–galanin communication may mediate effects of NPY on neuronal systems innervated by galanin, and therefore may play a pivotal role in the regulation of reproduction, growth, energy and metabolism.
ISSN:0306-4522
1873-7544
DOI:10.1016/j.neuroscience.2010.07.003