Rapid, reversible activation of AgRP neurons drives feeding behavior in mice
Michael J. Krashes ... Bryan L. Roth, Bradford B. Lowell
Michael J. Krashes ... Bryan L. Roth, Bradford B. Lowell
Published April 1, 2011
Citation Information: J Clin Invest. 2011;121(4):1424-1428. doi:10.1172/JCI46229.
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Categories: Brief Report Neuroscience

Rapid, reversible activation of AgRP neurons drives feeding behavior in mice

Abstract

Several different neuronal populations are involved in regulating energy homeostasis. Among these, agouti-related protein (AgRP) neurons are thought to promote feeding and weight gain; however, the evidence supporting this view is incomplete. Using designer receptors exclusively activated by designer drugs (DREADD) technology to provide specific and reversible regulation of neuronal activity in mice, we have demonstrated that acute activation of AgRP neurons rapidly and dramatically induces feeding, reduces energy expenditure, and ultimately increases fat stores. All these effects returned to baseline after stimulation was withdrawn. In contrast, inhibiting AgRP neuronal activity in hungry mice reduced food intake. Together, these findings demonstrate that AgRP neuron activity is both necessary and sufficient for feeding. Of interest, activating AgRP neurons potently increased motivation for feeding and also drove intense food-seeking behavior, demonstrating that AgRP neurons engage brain sites controlling multiple levels of feeding behavior. Due to its ease of use and suitability for both acute and chronic regulation, DREADD technology is ideally suited for investigating the neural circuits hypothesized to regulate energy balance.

Authors

Michael J. Krashes, Shuichi Koda, ChianPing Ye, Sarah C. Rogan, Andrew C. Adams, Daniel S. Cusher, Eleftheria Maratos-Flier, Bryan L. Roth, Bradford B. Lowell

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Cre-dependent AAV-hM3Dq-mCherry is specifically expressed in the ARC of ...

Figure 1

Cre-dependent AAV-hM3Dq-mCherry is specifically expressed in the ARC of AgRP-Ires-cre mice and confers activation by CNO.

(A) Design of hM3Dq-mCherry AAV employing the FLEX Switch strategy, which uses 2 pairs of heterotypic, antiparallel loxP-type recombination sites to achieve Cre-mediated transgene inversion and expression (12). L-ITR, left-inverted terminal repeat; R-ITR, right-inverted terminal repeat; WPRE, woodchuck hepatitis posttranscriptional regulatory element. (B) Top: Schematic indicating the site of the imaged area in the ARC of the hypothalamus. Bottom: mCherry fluorescence exclusively in the ARC after bilateral injections of AAV-hM3Dq-mCherry into the hypothalamus of AgRP-Ires-cre mice crossed with Z/EG Cre-dependent reporter mice. Z/EG mice expressed GFP protein following Cre-mediated excision of an intervening sequence (Scale bar: 100 μm). (C) Colocalization of mCherry (anti-dsRed) and anti-GFP fluorescence in the ARC. Note that GFP is cytoplasmic and DREADD is expressed on the plasma membrane (scale bar: 10 μm). (D) Whole cell, current clamp recording from an AgRP neuron marked by mCherry fluorescence from an AgRP-Ires-cre mouse injected with AAV-hM3Dq-mCherry. CNO (5 μM) elicited rapid depolarization of the membrane potential and greatly increased the firing rate. This example trace is representative of 4 similar recordings. (E) Injection of CNO in vivo induces c-fos immunoreactivity in the ARC. Brains were obtained for c-fos analysis 90 minutes following injection of saline or CNO (0.3 mg/kg of body weight, i.p.) (scale bars: 120 μm).