Context-drug-associations and reinstatement of drug-seeking behavior in male rats: Adolescent and adult time-dependent effects

Influence of reconsolidation in maintenance of cocaine-associated contextual memories formed during adolescence or adulthood

“…In this study, investigators combined a Coc-SA paradigm with passive presentation of a cocaine-associated cue to mimic human CET and observed that adult and adolescent rats displayed similar levels of EXT training behavior, as observed in our study, but were resistant to passive cue extinction compared to adults 29 . We have also noted a potential resistance to extinguish lever responses in adolescent rats within the original cocaine-paired context, but not within the EXT context 28 . Similar to our previous reports, adolescent rats had higher total inactive lever presses during reinstatement tests; however both age groups displayed increased inactive presses during the first 20 min bin of the reinstatement test.…”

“…Therefore, future directions should investigate the brain region specific mechanisms that strengthen cocaine-context memories in adult and adolescent rats. We recently demonstrated that adolescent cocaine-exposed rats display a time-dependent increase in context-induced cocaine-seeking behavior after 15 days of abstinence from cocaine intake, whereas adult cocaine-exposed counterparts do not 28 . Future studies could aim to use similar procedures of memory reactivation in a cocaine-paired context after extinction training and then examine whether reduced context-induced incubation of craving is observed in adolescent cocaine-exposed rats.…”

“…Previous reports did not find behavioral differences associated with single- vs pair-housed conditions using ABRV Coc-SA, therefore after a surgery and recovery period (2 days before behavioral start) all rats were single housed with adolescents maintained on 15 g and adults on 18 g of chow, which allowed for weight gain throughout the experiment 27 , 28 . All protocols were approved by the Institutional Animal Care and Use Committee (IACUC) at Michigan State University (MSU) and followed the National Research Council’s Guide for the Care and Use of Laboratory Rats.…”

Cocaine reward and reinstatement in adolescent versus adult rodents

“…A smaller set of studies used intermittent training schedules that alternate between cocaine available vs. non-available (45 vs. 15 min) periods (Anker et al, 2011;Schramm-Sapyta et al, 2011). A last set of studies conduced cocaine-SA (2h ShA) in an an environmental context in the absence of explicit-paired cue (Cho et al, 2020;Guerin et al, 2021;Olekanma et al, 2023)…”

“…At higher doses of 0.8 mg/kg cocaine, adolescents also had higher infusions than adults on training days 1-3, but similar infusions on training days 4-20, with equal responses during available and non-available periods throughout the 20 training days (Schramm-Sapyta et al, 2011). A final set of studies trained rats to self-administer cocaine at 0.3 or 0.6 mg/kg in a distinct environmental context and found that both age groups had similar responses and cocaine intake in the absence of explicit cocaine-paired cues (Cho et al, 2020;Guerin et al, 2021;Olekanma et al, 2023).…”