TABLE 4

Summary of preclinical studies on the telescoping effect

SourceDrug (dose/inf)RatsSA conditionsAddiction feature measured (procedure)Vulnerability to developing addiction-like features
Kerstetter et al. (2012)Cocaine
(0.4, 1.0 mg/kg)
39M/29FShA (FR1, up to 20 inf or food pellets, 5 days each)Preference for drug over other rewards (choice procedure): cocaine (0.4 or 1.0 mg/kg) vs. food (45 mg pellet). Sessions began after acquisition and were run for 5 days.F>M. Females were more likely than males to choose cocaine (low and high dose) over food (low dose, 59% vs. 33%; high dose, 76% vs. 68%)
Perry et al. (2013)Cocaine (0.4 mg/kg)12M/12FShA (30-min each: pellet only, cocaine only, cocaine vs. pellet choice; FR1, first 3 days then FR5 for 21 days)Preference for drug over other rewards (choice procedure): Cocaine vs. banana-flavored food pellet (45 mg pellet). Choice testing occurred daily after the pellet and cocaine only sessions.F>M. Females were likelihood than males to develop a preference for cocaine over food (50% vs. 17%)
Perry et al. (2015)Cocaine (0.4 mg/kg)50M/50FShA (30-min each: pellet only, cocaine only, cocaine vs. pellet choice; FR1, first 3 days then FR5 for 21 days)Preference for drug over other rewards (choice procedure): cocaine vs. banana-flavored food pellet (45 mg pellet). Choice testing occurred daily after the pellet and cocaine only sessions.F>M. Females were more likely than males to develop a preference for cocaine over food (42% vs. 26%)
Kawa and Robinson (2019)Cocaine (0.4 mg/kg)28M/24FShA (intermittent-access: 2, 5-min trials/h, 5-h/d, 5 days/week, 30 days)Enhanced motivation for the drug (threshold procedure): threshold tests (FR1, progressively decreasing doses of cocaine 1.28 to 0.004 mg/kg) were run following the 10th and 30th day of SA and again after 14 days of abstinence.F>M: Females developed an enhanced motivation for cocaine after less abstinence than males (i.e., following ten days of SA vs. following 30 days of SA and 14 days of abstinence)
Lynch and Taylor (2004)Cocaine (1.5 mg/kg)18M/20FExA (four 10-min trials/h, 24-h/d, 7 days)Enhanced motivation for the drug (PR schedule): PR testing with cocaine (0.5 mg/kg) was conducted prior to ExA SA and then again after ExA SA and 7 days of abstinence (3 sessions each)F>M: Females, but not males, developed an enhanced motivation for cocaine under these threshold conditions.
Towers et al. (2021)Cocaine (1.5 mg/kg)39M/38FExA (four 10-min trials/h, 24-h/d, 10 days)Enhanced motivation for the drug (PR schedule): PR testing with cocaine (0.5 mg/kg) was conducted prior to ExA SA and then again after ExA SA and 7, 14, or 60 days of abstinence (3 sessions each).
Compulsive use (histamine-punishment): Following the third PR session, histamine (0.4 mg/kg) was added to the cocaine solutions and three additional PR sessions were run.
F>M: Females develop an enhanced motivation for cocaine sooner during abstinence than males (7 vs. 14 days)
F>M: Females tested following 7 days of abstinence displayed greater compulsive use than males; males required more abstinence to reach the-female level of compulsivity (14 days).
Townsend et al. (2021)Fentanyl (0.32, 1.0 3.2, 10.0 ug/kg)18M/17FExA (FR5, 12-h/d, 5-day/wk, 3 weeks)Preference for drug over other rewards (choice procedure). Fentanyl vs. Ensure. Tested at the end of each week of ExA SA 8 h after last ExA sessionF>M: Males, but not females, showed withdrawal-induced increases in preference for fentanyl (at low doses), and methadone attenuated this effect.
  • ExA, extended-access; F, female; FR, fixed-ratio; M, male; PR, progressive-ratio; SA, self-administration; ShA, short-access.