Dissociation of hypothalamic npy from bat uncoupling protein mrna
in rats exposed to 24 hour thermoneutrality.
Bing, Chen, Helen Frankish, Qiong Wang, David Hopkins, Jacqueline
Keith, Paul Trayhurn, and Gareth Williams.
Department of Medicine, University of Liverpool, Liverpool, UK; and
Division of Biochemical Sciences, Rowett Research Institute,
Aberdeen, UK.
APStracts 2:0221R, 1995.
Neuropeptide Y (NPY) is increasingly considered to be involved in the
central regulation of energy balance. Our previous studies suggest
that hypothalamic NPY neurons of the arcuato-paraventricular (ARC
-PVN) projection are inhibited in association with the marked
increases in brown adipose tissue (BAT) thermogenesis and uncoupling
protein (UCP) gene expression in rats exposed to cold. We therefore
hypothesized that the NPYergic ARC-PVN system would be activated in a
thermoneutral environment, when energy expenditure falls to a
minimum, and that this activation could mediate the fall in BAT
activity. We measured regional hypothalamic NPY concentrations,
hypothalamic NPY receptor binding and NPY mRNA together with UCP mRNA
levels in rats exposed to thermoneutrality (290C) for 24 hours. At
thermoneutrality, UCP mRNA levels fell to 42% of those in controls
maintained at 220C, but there were no significant changes in
hypothalamic NPY or NPY mRNA levels, or in NPY receptor binding. We
conclude that the fall in UCP mRNA expression occurring under short
-term thermoneutral condition is mediated by neuroendocrine mechanisms
other than increased activity of hypothalamic NPY neurons.
Received 14 February 1995; accepted in final form 27 July 1995.
APS Manuscript Number R108-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.