Neurons synthesizing both thyrotropin-releasing hormone and urocortin 3 in the perifornical area innervate alpha-melanocyte-stimulating hormone-synthesizing neurons of the arcuate nucleus in rats
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1
Institute of Experimental Medicine, Hungarian Academy of Sciences, Laboratory of Endocrine Neurobiology, Hungary
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2
TUFTS-Medical Center, Tupper Research Institute and Department of Medicine, United States
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3
Tufts University School of Medicine, Department of Neuroscience, United States
Our laboratory has recently demonstrated that a group of neurons in the perifornical area of the hypothalamus co-synthesizes two anorexigenic peptides: TRH and UCN3. One of the main projection fields of these neurons is the ventromedial hypothalamus including the hypothalamic ventromedial and arcuate nuclei. Injection of TRH or UCN3 into this area inhibits food intake. Therefore, we hypothesized that the feeding related neurons of the arcuate nucleus may mediate the anorexigenic effect of TRH and UCN3 synthesized in the perifornical neurons. To determine the potential interaction of this perifornical neuronal group with the orexigenic NPY and anorexigenic α-MSH neurons of the arcuate nucleus, double- and triple-labeling immunocytochemistry were performed using antisera against TRH, UCN3, NPY and α-MSH.
Dense network of UCN3/TRH axons was found in the lateral part of the arcuate nucleus, where the α-MSH-synthesizing neurons reside, moreover triple-labeling immunocytochemistry demonstrated that the UCN3/TRH axons preferentially contacted with the α-MSH neurons. Only scattered NPY neurons were juxtaposed by double-labeled axons. The quantative analysis revealed that the UCN3/TRH axons contacted with the majority of the α-MSH neurons (~60 %), while UCN3/TRH boutons were in close apposition to no more than 7% of NPY synthesizing neurons. Moreover, approximately four times more double-labeled boutons were juxtaposed to the innervated α-MSH neurons than to the NPY cells (6,0 vs.1,7 boutons/innervated cell, respectively).
These results demonstrate that the perifornical UCN3/TRH neurons send projection to the anorexigenic α-MSH neurons of the arcuate nucleus. Since stress upregulates the UCN3 synthesis in the perifornical neurons and the α-MSH neurons of the arcuate nucleus are known to play role in the development of stress induced anorexia, we suggest that the stress induced anorexia is mediated, at least partly, through the perifornical region-arcuate nucleus pathway.
Conference:
IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010.
Presentation Type:
Poster Presentation
Topic:
Cellular neuroscience
Citation:
Nagyunyomi-Sényi
K,
Füzesi
T,
Zalai
D,
Kádár
A,
Liposits
Z,
Lechan
RM,
Wittmann
G and
Fekete
C
(2010). Neurons synthesizing both thyrotropin-releasing hormone and urocortin 3 in the perifornical area innervate alpha-melanocyte-stimulating hormone-synthesizing neurons of the arcuate nucleus in rats.
Front. Neurosci.
Conference Abstract:
IBRO International Workshop 2010.
doi: 10.3389/conf.fnins.2010.10.00097
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Received:
22 Apr 2010;
Published Online:
22 Apr 2010.
*
Correspondence:
Kata Nagyunyomi-Sényi, Institute of Experimental Medicine, Hungarian Academy of Sciences, Laboratory of Endocrine Neurobiology, Budapest, Hungary, katasenyi@yahoo.co.uk