(ORX/HCRT) system consists of a population of neurons located exclusively in the hypothalamus that produces the peptides ORX-A (HCRT-1) and ORX-B (HCRT-2), from the prepro-orexin/hypocretin peptide (de Lecea et al., 1998; Sakurai et al., 1998). Since the first publications related to this system in 1998, it has been widely appreciated that the ORX system participates in a number of behaviors critical for the survival of an organism (de Lecea Sutcliffe, 1999; Sakurai, 2007; Tsujino Sakurai, 2013; Gao Horvath, 2014; Mahler et al., 2014). The ORX system plays an important role in regulating sleep/wake activity, and dysregulation of the ORX system is associated with narcolepsy with cataplexy (Sakurai, 2007; de Lecea Huerta, 2014). In addition, we and others have demonstrated a strong association between the ORX system and multiple types of motivated behavior (Harris et al., 2005; Aston-Jones et al., 2009; Borgland et al., 2009; Thompson Borgland, 2011; Tsujino Sakurai, 2013; Mahler et al., 2014; Merlo Pich Melotto, 2014; Yeoh et al., 2014). The ORX system is involved in feeding behaviors (Sakurai et al., 1998), and also has a profound influence on motivation for drugs of abuse (Mahler et al., 2012), including alcohol (Lawrence, 2010; Mahler et al., 2012; Brown Lawrence, 2013). Lawrence and colleagues first reported an association between the ORX system and alcohol seeking, demonstrating that ethanol (EtOH) consumption increased ORX mRNA, and that pharmacological blockade of the ORX-1 receptor (OX1R) decreased EtOH seeking behaviors (Lawrence et al., 2006). The effect of OX1R antagonism on alcohol seeking and drinking has been demonstrated by a number of groups (Lawrence, 2010; Mahler et al., 2012; Khoo Brown, 2014). We and others showed that blocking OX1R activity decreases alcohol seeking preferentially in highly-motivated animals (Moorman Aston-Jones, 2009; Anderson et al., 2014; Olney et al., 2015). This relationship between motivation for reward and ORX Oxaliplatin web signaling led us to propose that the ORX system plays a major role in motivational activation, in which ORX neuron activation scales with intensity of motivational drive (Mahler et al., 2014). Further work is AMN107 supplier needed to refine our understanding of the relationship between ORX neuron activation and motivational state, particularly with respect to alcohol seeking. Although several reports have documented that ORX receptor antagonism decreases motivation for alcohol (Richards et al., 2008; Moorman Aston-Jones, 2009; Jupp et al., 2011; Anderson et al., 2014; Olney et al., 2015), few studies have shown an effect of blocking OX1Rs or OX2Rs on alcohol seeking (Dhaher et al., 2010) or alcohol preference (Moorman AstonJones, 2009; Voorhees Cunningham, 2011; Brown et al., 2013; Anderson et al., 2014; Barson et al., 2015). Moreover, this evidence is limited by findings that certain ORX receptor antagonists may exhibit reduced selectivity in certain conditions (Hollander et al., 2012; McElhinny et al., 2012; Merlo Pich Melotto, 2014; Winrow Renger, 2014). The above findings indicate the need to measure activity of ORX neurons to better understand their roles in alcohol-related behaviors. An important and additional factor that supports this conclusion is that ORX neuron populations play multiple, diverse roles in motivated behaviors (Tsujino Sakurai, 2013; Mahler et al., 2014). In particular, ORX neurons located in the lateral region of the orexin cell field function i.(ORX/HCRT) system consists of a population of neurons located exclusively in the hypothalamus that produces the peptides ORX-A (HCRT-1) and ORX-B (HCRT-2), from the prepro-orexin/hypocretin peptide (de Lecea et al., 1998; Sakurai et al., 1998). Since the first publications related to this system in 1998, it has been widely appreciated that the ORX system participates in a number of behaviors critical for the survival of an organism (de Lecea Sutcliffe, 1999; Sakurai, 2007; Tsujino Sakurai, 2013; Gao Horvath, 2014; Mahler et al., 2014). The ORX system plays an important role in regulating sleep/wake activity, and dysregulation of the ORX system is associated with narcolepsy with cataplexy (Sakurai, 2007; de Lecea Huerta, 2014). In addition, we and others have demonstrated a strong association between the ORX system and multiple types of motivated behavior (Harris et al., 2005; Aston-Jones et al., 2009; Borgland et al., 2009; Thompson Borgland, 2011; Tsujino Sakurai, 2013; Mahler et al., 2014; Merlo Pich Melotto, 2014; Yeoh et al., 2014). The ORX system is involved in feeding behaviors (Sakurai et al., 1998), and also has a profound influence on motivation for drugs of abuse (Mahler et al., 2012), including alcohol (Lawrence, 2010; Mahler et al., 2012; Brown Lawrence, 2013). Lawrence and colleagues first reported an association between the ORX system and alcohol seeking, demonstrating that ethanol (EtOH) consumption increased ORX mRNA, and that pharmacological blockade of the ORX-1 receptor (OX1R) decreased EtOH seeking behaviors (Lawrence et al., 2006). The effect of OX1R antagonism on alcohol seeking and drinking has been demonstrated by a number of groups (Lawrence, 2010; Mahler et al., 2012; Khoo Brown, 2014). We and others showed that blocking OX1R activity decreases alcohol seeking preferentially in highly-motivated animals (Moorman Aston-Jones, 2009; Anderson et al., 2014; Olney et al., 2015). This relationship between motivation for reward and ORX signaling led us to propose that the ORX system plays a major role in motivational activation, in which ORX neuron activation scales with intensity of motivational drive (Mahler et al., 2014). Further work is needed to refine our understanding of the relationship between ORX neuron activation and motivational state, particularly with respect to alcohol seeking. Although several reports have documented that ORX receptor antagonism decreases motivation for alcohol (Richards et al., 2008; Moorman Aston-Jones, 2009; Jupp et al., 2011; Anderson et al., 2014; Olney et al., 2015), few studies have shown an effect of blocking OX1Rs or OX2Rs on alcohol seeking (Dhaher et al., 2010) or alcohol preference (Moorman AstonJones, 2009; Voorhees Cunningham, 2011; Brown et al., 2013; Anderson et al., 2014; Barson et al., 2015). Moreover, this evidence is limited by findings that certain ORX receptor antagonists may exhibit reduced selectivity in certain conditions (Hollander et al., 2012; McElhinny et al., 2012; Merlo Pich Melotto, 2014; Winrow Renger, 2014). The above findings indicate the need to measure activity of ORX neurons to better understand their roles in alcohol-related behaviors. An important and additional factor that supports this conclusion is that ORX neuron populations play multiple, diverse roles in motivated behaviors (Tsujino Sakurai, 2013; Mahler et al., 2014). In particular, ORX neurons located in the lateral region of the orexin cell field function i.
