E and fasting reinforces NO-mediated enhancement of GABAergic currents [14]. Although a recent study further identifies genes that are highly expressed in the 
DMH using microarray analysis [15], little information is available about molecular markers specific for the DMH, which would facilitate the development of mouse models with DMH-specific genetic manipulations. Central CP21 cholinergic circuits, and the consequent activation of both nicotinic and muscarinic receptor-mediated components, appear to play a role in the regulation of ingestive behavior [16]. In particular, activation of CNS nicotinic receptors leads to a reduction in energy intake via modulation of melanocortinergic neurons such as pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP) neurons in the arcuate nucleus [17,18]. In contrast, mice lacking the M3 muscarinic receptor show a significant decrease in food intake and body weight. Genetic deletion ofDMH Cholinergic Neuronsthe M3 receptors is associated with altered expression of AgRP, POMC and melanin-concentrating hormone (MCH) peptides that are expressed in the arcuate and lateral hypothalamus [19]. At least, one study prior to this showed a cluster of cholinergic neurons in the DMH, but the function of these DMH cholinergic neurons was unknown. [20]. DMH neurons send abundant projections to the paraventricular nucleus, preoptic area, arcuate nucleus, and lateral hypothalamus [21]. It is thus plausible that, at least, a subset of DMH neurons are cholinergic and that the DMH cholinergic neurons play a role in overall energy balance via interactions between the DMH and other hypothalamic nuclei, including the arcuate and lateral hypothalamic nuclei. Using a BAC transgenic mouse model where cholinergic neurons are labeled with the tauGFP fusion protein driven by the choline acetyltransferase promoter [22], we first examined whether we could detect cholinergic neurons in the DMH. We then tested whether synaptic activity of the DMH cholinergic neurons was altered by changes in the availability of nutrients. We found that a single, overnight food deprivation increased fos protein in the DMH cholinergic neurons, as compared to control. This was associated with increased baseline resting membrane potential and decreased inhibitory tone onto cholinergic neurons. Thus, our data indicate that cholinergic neurons within the DMH are a good nutrient-sensitive neuronal marker within this area and that these cholinergic neurons may play an essential role in hypothalamic synapses and circuits that regulate overall energy balance.MgATP and 10 phosphocreatine. All Z-360 recordings were conducted at 28uC. GABAergic currents were isolated with the addition of 6Cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 mM; Abcam) and D-amino-phosphovaleric acid (D-AP-5, 50 mM; Abcam) and glutamatergic currents were recorded in the presence of bicuculline (10 mM; Abcam). Membrane currents were recorded with a Multiclamp 700B or an Axopatch 200B (Molecular Devices) in whole-cell configuration. Electrophysiological signals were lowpass filtered at 2? kHz, stored on a PC and analyzed offline with pClamp 10 software (Molecular devices).Analysis of Spontaneous Miniature IPSCsSpontaneous miniature inhibitory and excitatory postsynaptic currents were recorded in the presence of tetrodotoxin (TTX) (1 mM; Sigma-aldrich). Autodetected events with a scaled template were also visually examined to correct for noise fluctuation (Clampfit 10, Molecular devices). Analy.E and fasting reinforces NO-mediated enhancement of GABAergic currents [14]. Although a recent study further identifies genes that are highly expressed in the DMH using microarray analysis [15], little information is available about molecular markers specific for the DMH, which would facilitate the development of mouse models with DMH-specific genetic manipulations. Central cholinergic circuits, and the consequent activation of both nicotinic and muscarinic receptor-mediated components, appear to play a role in the regulation of ingestive behavior [16]. In particular, activation of CNS nicotinic receptors leads to a reduction in energy intake via modulation of melanocortinergic neurons such as pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP) neurons in the arcuate nucleus [17,18]. In contrast, mice lacking the M3 muscarinic receptor show a significant decrease in food intake and body weight. Genetic deletion ofDMH Cholinergic Neuronsthe M3 receptors is associated with altered expression of AgRP, POMC and melanin-concentrating hormone (MCH) peptides that are expressed in the arcuate and lateral hypothalamus [19]. At least, one study prior to this showed a cluster of cholinergic neurons in the DMH, but the function of these DMH cholinergic neurons was unknown. [20]. DMH neurons send abundant projections to the paraventricular nucleus, preoptic area, arcuate nucleus, and lateral hypothalamus [21]. It is thus plausible that, at least, a subset of DMH neurons are cholinergic and that the DMH cholinergic neurons play a role in overall energy balance via interactions between the DMH and other hypothalamic nuclei, including the arcuate and lateral hypothalamic nuclei. Using 
a BAC transgenic mouse model where cholinergic neurons are labeled with the tauGFP fusion protein driven by the choline acetyltransferase promoter [22], we first examined whether we could detect cholinergic neurons in the DMH. We then tested whether synaptic activity of the DMH cholinergic neurons was altered by changes in the availability of nutrients. We found that a single, overnight food deprivation increased fos protein in the DMH cholinergic neurons, as compared to control. This was associated with increased baseline resting membrane potential and decreased inhibitory tone onto cholinergic neurons. Thus, our data indicate that cholinergic neurons within the DMH are a good nutrient-sensitive neuronal marker within this area and that these cholinergic neurons may play an essential role in hypothalamic synapses and circuits that regulate overall energy balance.MgATP and 10 phosphocreatine. All recordings were conducted at 28uC. GABAergic currents were isolated with the addition of 6Cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 mM; Abcam) and D-amino-phosphovaleric acid (D-AP-5, 50 mM; Abcam) and glutamatergic currents were recorded in the presence of bicuculline (10 mM; Abcam). Membrane currents were recorded with a Multiclamp 700B or an Axopatch 200B (Molecular Devices) in whole-cell configuration. Electrophysiological signals were lowpass filtered at 2? kHz, stored on a PC and analyzed offline with pClamp 10 software (Molecular devices).Analysis of Spontaneous Miniature IPSCsSpontaneous miniature inhibitory and excitatory postsynaptic currents were recorded in the presence of tetrodotoxin (TTX) (1 mM; Sigma-aldrich). Autodetected events with a scaled template were also visually examined to correct for noise fluctuation (Clampfit 10, Molecular devices). Analy.