Abstract
As melanin-concentrating hormone (MCH) neurons express the neurokinin 3 receptor (NK3) in the rat diencephalon, their innervation by tachykininergic fibers, the origin of this innervation and the effect of a NK3 agonist on MCH mRNA expression were researched. The obtained results show that the tachykininergic system develops complex relationships with MCH neurons. Overall, MCH cell bodies appeared targeted by both NKB- and SP-inputs. These afferents have multiple hypothalamic and extra-hypothalamic origins, but a local (intra-lateral hypothalamic area) origin from small interneurons was suspected as well. MCH cell bodies do not express NK1, but around 2.7% of the MCH neurons contained SP after colchicine injection. Senktide, a NK3 agonist, produced an increase of the MCH mRNA expression in cultured hypothalamic slices. This effect was reversed by two NK3 antagonists. Tachykinins enhance MCH mRNA expression, and, thus, may modulate the effect of MCH in functions such as feeding and reproductive behaviors in which this peptide has been experimentally involved.
MeSH terms
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Animals
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Brain / cytology
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Brain / metabolism
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Colchicine / metabolism
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Feeding Behavior / physiology
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Hypothalamic Hormones / metabolism*
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Hypothalamus / cytology
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Hypothalamus / metabolism*
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Interneurons / cytology
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Interneurons / metabolism
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Male
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Melanins / metabolism*
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Neural Pathways / cytology
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Neural Pathways / metabolism*
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Neurokinin B / agonists
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Neurokinin B / antagonists & inhibitors
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Neurokinin B / metabolism
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Neurokinin-1 Receptor Antagonists
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Neurons / cytology
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Neurons / metabolism*
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Organ Culture Techniques
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Peptide Fragments / pharmacology
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Piperidines / pharmacology
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Pituitary Hormones / metabolism*
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RNA, Messenger / drug effects
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RNA, Messenger / metabolism
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Rats
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Rats, Sprague-Dawley
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Receptors, Neurokinin-1 / agonists
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Receptors, Neurokinin-1 / genetics
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Receptors, Neurokinin-3 / agonists
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Receptors, Neurokinin-3 / antagonists & inhibitors
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Receptors, Neurokinin-3 / genetics*
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Sexual Behavior / physiology
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Substance P / analogs & derivatives*
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Substance P / metabolism
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Substance P / pharmacology
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Tachykinins / metabolism*
Substances
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Hypothalamic Hormones
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Melanins
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Neurokinin-1 Receptor Antagonists
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Peptide Fragments
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Piperidines
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Pituitary Hormones
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RNA, Messenger
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Receptors, Neurokinin-1
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Receptors, Neurokinin-3
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Tachykinins
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senktide
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Substance P
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melanin-concentrating hormone
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Neurokinin B
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SR 142801
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Colchicine