“…It should be noted that acute systemic administration of low-dose LPS (~100 μg/kg) has been reported to either decrease tissue DA content or increase extracellular DA metabolites in the NAcc (van Heesch et al, 2014;Yeh et al, 2015). However, these studies assessed DA and 'anhedonic' behavior (sucrose preference or responding for brain stimulation) at 2-4 h post LPS (van Heesch et al, 2014;van Heesch et al, 2013;Yeh et al, 2015), a time point that may be confounded due to the febrile effects of LPS and related sickness behaviors (Dinarello, 2004;Frenois et al, 2007;O'Connor et al, 2009b). These early effects of LPS may also reflect, for instance, acute activation of neuroendocrine peptides and hormones (minutes to hours), which can have stimulatory effects on turnover or release of brain catecholamines (Barrot et al, 2000;Lavicky and Dunn, 1993;Matsuzaki et al, 1989;Mekaouche et al, 1996), and which may occur ahead of the more chronic mechanisms by which inflammation is thought to contribute to decreased DA availability (see the section 'Mechanisms of inflammation effects on dopamine synthesis and release' below for detailed discussion).…”