The overall goal is to characterize the role that hypothalamic neuropeptide Y mechanisms play in controlling daily torpor, an extreme form of temperature regulation that evolved to help animals contend with limited food availability. The central and peripheral neural mechanisms integrating overall energy balance and torpor will be explored. Annual rhythms of food intake and body mass, reproduction, and daily torpor are well documented in the Siberian hamster (Phodopus sungorus), the model species in all experiments.
Specific aims i nclude: 1) measuring and contrasting hypothalamic neuropeptide and neuropeptide mRNA levels, especially neuropeptide Y, in torpid and non-torpid Siberian hamsters; 2) examining whether pretreatment with a neuropeptide Y receptor antagonist can prevent spontaneous and/or 2DG-induced torpor; 3) determining whether successive NPY infusions produce prolonged hypothermia; 4) evaluating whether inhibiting thermogenesis by blocking norepinephrine receptors at brown adipose tissue produces torpor-like hypothermia. Much remains that we do not understand about the physiological mechanisms underlying the control of energy balance and thermoregulation. Delineating the interaction between specific neural pathways and neurotransmitters and daily torpor in a model system like the Siberian hamster could provide important insights into the regulation of these processes for mammals in general and humans in particular. A better understanding of the mechanisms of reversible hypothermia is of medical import. The reduced metabolism, blood flow, etc. coincident with hypothermia may be very beneficial during many types of major surgery, especially organ transplants. Little is known at this time of the mechanism that allows Siberian hamsters and several other species to undergo hypothermia which is lethal to humans and most other mammals. The proposed research addresses fundamental questions in regulatory biology and, thereby, affords the opportunity of establishing general principles applicable to all mammals.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
2R01NS030816-11A1
Application #
6774239
Study Section
Special Emphasis Panel (ZRG1-NNB (01))
Program Officer
Mitler, Merrill
Project Start
1996-09-16
Project End
2007-03-31
Budget Start
2004-04-01
Budget End
2005-03-31
Support Year
11
Fiscal Year
2004
Total Cost
$280,160
Indirect Cost
Name
University of California Berkeley
Department
Psychology
Type
Schools of Arts and Sciences
DUNS #
124726725
City
Berkeley
State
CA
Country
United States
Zip Code
94704
Dark, John; Pelz, Kimberly M (2008) NPY Y1 receptor antagonist prevents NPY-induced torpor-like hypothermia in cold-acclimated Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 294:R236-45
Pelz, Kimberly M; Routman, David; Driscoll, Joseph R et al. (2008) Monosodium glutamate-induced arcuate nucleus damage affects both natural torpor and 2DG-induced torpor-like hypothermia in Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 294:R255-65
Pelz, Kimberly M; Dark, John (2007) ICV NPY Y1 receptor agonist but not Y5 agonist induces torpor-like hypothermia in cold-acclimated Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 292:R2299-311
Park, Jin Ho; Dark, John (2007) Fos-like immunoreactivity in Siberian hamster brain during initiation of torpor-like hypothermia induced by 2DG. Brain Res 1161:38-45
Dark, John (2005) Annual lipid cycles in hibernators: integration of physiology and behavior. Annu Rev Nutr 25:469-97
Paul, Matthew J; Freeman, David A; Park, Jin Ho et al. (2005) Neuropeptide Y induces torpor-like hypothermia in Siberian hamsters. Brain Res 1055:83-92
Freeman, David A; Lewis, Daniel A; Kauffman, Alexander S et al. (2004) Reduced leptin concentrations are permissive for display of torpor in Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 287:R97-R103
Dark, J; Miller, D R; Lewis, D A et al. (2003) Noradrenaline-induced lipolysis in adipose tissue is suppressed at hibernation temperatures in ground squirrels. J Neuroendocrinol 15:451-8
Lewis, D; Freeman, D A; Dark, J et al. (2002) Photoperiodic control of oestrous cycles in Syrian hamsters: mediation by the mediobasal hypothalamus. J Neuroendocrinol 14:294-9
Bae, H H; Stamper, J L; Heydorn, E C et al. (2000) Role of area postrema in control of torpor in Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 279:R591-8

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