High temporal resolution of amino acid levels in rat nucleus accumbens during operant ethanol self‐administration: involvement of elevated glycine in anticipation

Abstract

Capillary electrophoresis coupled with laser-induced fluorescence detection (CE-LIF) provides 15-s temporal resolution of amino acid levels in microdialysate, which, for the first time, allows almost real time measurement of changes during episodes of behavior. We trained Sprague-Dawley rats to self-administer either 10% ethanol-containing gelatin or non-alcoholic gelatin in a typical operant chamber. After rats reached stable daily levels of responding, microdialysis probes were inserted into nucleus accumbens and samples were collected before, during and after operant sessions with on-line analysis via CE-LIF. During the first 15 min of the operant session, there was a significant increase in taurine that correlated with the amount of ethanol consumed (R2 = 0.81) but no change in rats responding for plain gel. There were large, consistent increases in glycine in both the ethanol and plain gel groups which correlated with the amount of gel consumed. A smaller increase was observed in rats with free non-operant access to plain gel compared to the increase seen with the same amount of gel consumed under operant conditions. When rats were given a time out after each delivery of gel in the operant protocol, the greatest increase of glycine was obtained with the longest time out period. Thus, increases in glycine in nucleus accumbens appear to be related to anticipation of reinforcement.

Risk preference following adolescent alcohol use is associated with corrupted encoding of costs but not rewards by mesolimbic dopamine

“…Adolescent rats [postnatal day (PND) [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] were provided with continuous access to gelatin shots (10% EtOH or control gelatin) for 20 d (Fig. 1A).…”

“…Jars were sealed and refrigerated overnight. This procedure was designed to minimize evaporation of ethanol and has been validated to yield accurate ethanol content (29) and to lead to alterations in brain chemistry (30,31). Alcohol presentation involved allowing jars of gelatin to warm to room temperature and recording their weight.…”

Chronic Alcohol Intake During Adolescence, but not Adulthood, Promotes Persistent Deficits in Risk-Based Decision Making

“…Preparation was as previously described (Clark et al, 2012; Nasrallah et al, 2009; Nasrallah et al, 2011; Rowland et al, 2005). The ethanol-gels were designed to minimize evaporation of ethanol and have been previously validated to result in accurate ethanol content (Rowland et al, 2005) and to produce alterations in brain chemistry (Li et al, 2008; Peris et al, 2006). The gels were made available 24h/day, unless otherwise noted, in addition to ad libitum water and chow, and fresh gel-containing jars were presented every day.…”

Long-term risk preference and suboptimal decision making following adolescent alcohol use

“…Intake of these alcohol ''Jello Shots'' resulted in significant elevations of blood alcohol concentrations (6) in the range of 5 to 45 mg % with a linear relationship to amount consumed (r ϭ 0.94). Furthermore, alterations in brain chemistry in association with this administration protocol have also been documented (7)(8). Since this delivery method does not require training to promote intake, it is particularly appropriate for developmental studies, such as those focused on adolescence, since, in rodents, this period is relatively brief.…”