CART is expressed in refeeding-activated neurons of the ventral parvocellular part of the hypothalamic paraventricular nucleus
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1
Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungary
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2
Tupper Research Institute and Department of Medicine , New England Medical Center, United States
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3
Department of Neuroscience, Tufts University School of Medicine, United States
Refeeding after a period of fasting results in satiety and melanocortin-mediated activation of neurons in the ventral parvocellular subdivision of the PVN (vPVN) suggesting that the vPVN is an important component of the melanocortin signaling system. Since the anorexigenic peptide, CART is expressed in vPVN neurons, we hypothesized that CART synthesized by these neurons may contribute to the satiety effects of α-MSH. To test this hypothesis, double-labeling combined immunofluorescence for c-Fos protein, as a marker of neuronal activation, and isotopic in situ hybridization for CART mRNA detection was performed on hypothalamic sections of fasting and refed (2h) rats. The ratio of activated CART neurons was quantified in the vPVN. C-Fos-immunoreactivity was absent in the entire PVN of fasted animals. In contrast, following refeeding, c-Fos-containing neurons were observed in the PVN, including the strongly labeled vPVN. The most intense CART mRNA signal was detected in the medial part of the vPVN, but neurons with less intense CART mRNA expression were also observed throughout the vPVN. Analyses of double-labeled preparations demonstrated that 44 ± 2 % of the activated neurons in vPVN contained CART mRNA, while 58 ± 8 % of CART-synthesizing neurons in this region contained c-Fos-immunoreactivity. These data demonstrate that CART is synthesized in approximately half of the refeeding-activated neurons in the vPVN. Since the vPVN neurons are activated by the melanocortin system, CART may be involved in relaying the satiety effects of melanocortins to downstream target centers.
Conference:
12th Meeting of the Hungarian Neuroscience Society, Budapest, Hungary, 22 Jan - 24 Jan, 2009.
Presentation Type:
Poster Presentation
Topic:
Homeostatic regulatory mechanisms
Citation:
Füzesi
T,
Wittmann
G,
Liposits
Z,
Lechan
RM and
Fekete
C
(2009). CART is expressed in refeeding-activated neurons of the ventral parvocellular part of the hypothalamic paraventricular nucleus.
Front. Syst. Neurosci.
Conference Abstract:
12th Meeting of the Hungarian Neuroscience Society.
doi: 10.3389/conf.neuro.01.2009.04.231
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Received:
13 Mar 2009;
Published Online:
13 Mar 2009.
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Correspondence:
Tamás Füzesi, Department of Endocrine Neurobiology, Institute of Experimental Medicine, Budapest, Hungary, fuzesi@koki.hu