The VMH and Molecular Control of Energy Balance The ventral medial hypothalamus (VMH), in concert with other brain regions, regulates energy balance. A group of neurons within the VMH, marked by the expression of the transcription factor, SF1 (Nr5a1), resists the development of obesity. The adipocyte-derived, """"""""catabolic"""""""" hormone leptin excites these SF1 neurons, and deletion of leptin receptors (LEPRs) on SF1 neurons results in obesity, and also marked sensitivity to diet-induced obesity. Thus, SF1 neurons in the VMH, like POMC neurons in the actuate nucleus, are direct targets of leptin and promote negative energy balance. While much is known about how POMC neurons cause weight loss, comparatively less is known about how SF1 neurons achieve this effect. This presents the unique opportunity to identify novel mechanisms controlling energy homeostasis. In this grant, we propose to determine the following: 1) the """"""""catabolic"""""""" factor released by SF1 neurons (we propose an important role for the neuropeptide, PACAP) (Aim 1), 2) the receptor and neuron immediately downstream of SF1 neurons (we propose that the PAC1-receptor - the high affinity PACAP receptor - on POMC neurons is important) (Aim 2), and 3) on the afferent side of SF1 neurons, we propose that glutamatergic excitatory inputs, which synapse on dendritic spines of SF1 neurons, play a key role in controlling the activity of SF1 neurons, and that glutamate NMDA receptor-mediated plasticity of these inputs, and, importantly, leptin regulation of this plasticity, contributes prominently to the control of energy homeostasis. To accomplish these Aims, we will utilize the following state-of-the-art technologies: 1) neuron- specific gene manipulation to test molecular mechanisms in an in vivo context (in all three Aims), 2) optogenetics to identify functionally relevant, monosynaptic, downstream targets of SF1 neurons (in Aim 2), and 3) functional and morphologic assessments of excitatory synaptic plasticity (in Aim 3).

Public Health Relevance

Complex neurocircuits in the brain work in concert to control body fat stores. In order to intelligently develop anti-obesity therapies, it is first necessary to decipher the """"""""wiring-diagrams"""""""" that underpin these circuits. To accomplish this, our group is using the following state-of-the-art technologies: 1) neuron-specific gene manipulations, 2) optogenetics (light-activated neuron stimulation), and 3) functional-morphologic assessments of synaptic organization and plasticity.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK071051-09
Application #
8417750
Study Section
Integrative Physiology of Obesity and Diabetes Study Section (IPOD)
Program Officer
Hyde, James F
Project Start
2005-04-01
Project End
2015-02-28
Budget Start
2013-03-01
Budget End
2014-02-28
Support Year
9
Fiscal Year
2013
Total Cost
$348,670
Indirect Cost
$148,285
Name
Beth Israel Deaconess Medical Center
Department
Type
DUNS #
071723621
City
Boston
State
MA
Country
United States
Zip Code
02215
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