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Andermann, Mark

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Andermann

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Andermann, Mark

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2015 - 20172

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Author's Publications: search.filters.isAuthorOfPublication.7d98c09d-eff5-4282-a9bd-d0ccb7177648

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    Arcuate hypothalamic AgRP and putative POMC neurons show opposite changes in spiking across multiple timescales
    (eLife Sciences Publications, Ltd, 2015) Mandelblat-Cerf, Yael; Ramesh, Rohan; Burgess, Christian R; Patella, Paola; Yang, Zongfang; Lowell, Bradford; Andermann, Mark
    Agouti-related-peptide (AgRP) neurons—interoceptive neurons in the arcuate nucleus of the hypothalamus (ARC)—are both necessary and sufficient for driving feeding behavior. To better understand the functional roles of AgRP neurons, we performed optetrode electrophysiological recordings from AgRP neurons in awake, behaving AgRP-IRES-Cre mice. In free-feeding mice, we observed a fivefold increase in AgRP neuron firing with mounting caloric deficit in afternoon vs morning recordings. In food-restricted mice, as food became available, AgRP neuron firing dropped, yet remained elevated as compared to firing in sated mice. The rapid drop in spiking activity of AgRP neurons at meal onset may reflect a termination of the drive to find food, while residual, persistent spiking may reflect a sustained drive to consume food. Moreover, nearby neurons inhibited by AgRP neuron photostimulation, likely including satiety-promoting pro-opiomelanocortin (POMC) neurons, demonstrated opposite changes in spiking. Finally, firing of ARC neurons was also rapidly modulated within seconds of individual licks for liquid food. These findings suggest novel roles for antagonistic AgRP and POMC neurons in the regulation of feeding behaviors across multiple timescales. DOI: http://dx.doi.org/10.7554/eLife.07122.001
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    Dynamic GABAergic afferent modulation of AgRP neurons
    (2017) Garfield, Alastair S; Shah, Bhavik P; Burgess, Christian R; Li, Monica; Li, Chia; Steger, Jennifer S; Madara, Joseph; Campbell, John; Kroeger, Daniel; Scammell, Thomas; Tannous, Bakhos; Myers, Martin G; Andermann, Mark; Krashes, Michael J; Lowell, Bradford
    Agouti-related peptide (AgRP) neurons of the arcuate nucleus of the hypothalamus (ARC) promote homeostatic feeding at times of caloric insufficiency, yet they are rapidly suppressed by food-related sensory cues prior to ingestion. Here we identify a highly selective inhibitory afferent to AgRP neurons that serves as a neural determinant of this rapid modulation. Specifically, GABAergic projections arising from the ventral compartment of the dorsomedial nucleus of the hypothalamus (vDMH) contribute to the pre-consummatory modulation of ARCAgRP neurons. In a manner reciprocal to ARCAgRP neurons, ARC-projecting leptin receptor (LepR)-expressing GABAergic DMH neurons exhibit rapid activation upon availability of food that additionally reflects the relative value of the food. Thus, DMHLepR neurons form part of the sensory network that relays real-time information about the nature and availability of food to dynamically modulate ARCAgRP neuron activity and feeding behavior.