TABLE 4.
Summary of preclinical studies on the telescoping effect
| Source | Drug (dose/inf) | Rats | SA conditions | Addiction feature measured (procedure) | Vulnerability to developing addiction-like features |
|---|---|---|---|---|---|
| Kerstetter et al. (2012) | Cocaine (0.4, 1.0 mg/kg) |
39M/29F | ShA (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/12F | ShA (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/50F | ShA (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/24F | ShA (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/20F | ExA (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/38F | ExA (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/17F | ExA (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 session | F>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.