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Ventromedial arcuate nucleus communicates peripheral metabolic information to the suprachiasmatic nucleus.

Yi, C.-X. and Vliet, J. van der and Dai, J. and Yin, G. and Ru, L. and Buijs, R.M. (2006) Ventromedial arcuate nucleus communicates peripheral metabolic information to the suprachiasmatic nucleus. Endocrinology, 147(1), 283-294. ISSN 00137227. doi: 10.1210/en.2005-1051.

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Abstract

The arcuate nucleus (ARC) is crucial for the maintenance of energy homeostasis as an integrator of long- and short-term hunger and satiety signals. The expression of receptors for metabolic hormones, such as insulin, leptin, and ghrelin, allows ARC to sense information from the periphery and signal it to the central nervous system. The ventromedial ARC (vmARC) mainly comprises orexigenic neuropeptide agouti-related peptide and neuropeptide Y neurons, which are sensitive to circulating signals. To investigate neural connections of vmARC within the central nervous system, we injected the neuronal tracer cholera toxin B into vmARC. Due to variation of injection sites, tracer was also injected into the subependymal layer of the median eminence (seME), which showed similar projection patterns as the vmARC. We propose that the vmARC forms a complex with the seME, their reciprocal connections with viscerosensory areas in brain stem, and other circumventricular organs, suggesting the exchange of metabolic and circulating information. For the first time, the vmARC-seME was shown to have reciprocal interaction with the suprachiasmatic nucleus (SCN). Activation of vmARC neurons by systemic administration of the ghrelin mimetic GH-releasing peptide-6 combined with SCN tracing showed vmARC neurons to transmit feeding related signals to the SCN. The functionality of this pathway was demonstrated by systemic injection of GH-releasing peptide-6, which induced Fos in the vmARC and resulted in a reduction of about 40% of early daytime Fos immunoreactivity in the SCN. This observation suggests an anatomical and functional pathway for peripheral hormonal feedback to the hypothalamus, which may serve to modulate the activity of the SCN.

Item Type:Article
Additional Information:doi: 10.1210/en.2005-1051
Institutes:Netherlands Institute for Neuroscience (NIN)
ID Code:3649
Deposited On:13 Feb 2009 17:14
Last Modified:10 Dec 2009 13:14

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