My research is directed toward developing behavioral and pharmacological methods of reducing and preventing drug abuse. Animals are trained to self-administer drugs that humans abuse, and several phases of the addiction process are modeled, such as acquisition, maintenance, withdrawal, craving, and relapse. Our laboratory tests a number of therapeutic drugs, such as antidepressants and opioid and dopamine agonists and antagonists; they have shown considerable efficacy in reducing drug self-administration. Behavioral methods that are proving effective are enriching the environment with alternative nondrug reinforcers; for example, food and sweet-tasting drinking solutions. Behavioral economic analyses quantify the reinforcing efficacy of the drug under varied environmental and pharmacological treatments. Recent work shows that the greatest reduction in drug self-administration is achieved when behavioral and pharmacological treatments are combined. We are also interested in the interrelationships of feeding and drug abuse, and in testing the notion of common reward mechanisms for drugs, food, and other nondrug substances and events.
Another topic of study in our laboratory is the dependence producing effect of drugs. We have found that sensitive behavioral performance measures reveal subtle behavioral deficits due to drug withdrawal when no physical signs are present. Further, these behavioral deficits last for long periods of time, and may be a factor contributing to relapse to drug abuse in humans. Behavioral disturbances have been measured after low drug doses and short or intermittent periods of access with drugs such as caffeine, nicotine, cocaine, and phencyclidine (PCP), dispelling the common notion that excessive or long term drug abuse is necessary to produce withdrawal effects. We are using this model to find pharmacological and behavioral strategies to relieve withdrawal distress.
(For a comprehensive list of recent publications, refer to PubMed, a service provided by the National Library of Medicine.)
Smethells JR, Carroll ME. Discrepant effects of acute cocaine on impulsive choice (delay discounting) in female rats during an increasing- and adjusting-delay procedure. Psychopharmacology (Berl). 2015 Feb 28;.
Holtz NA, Radke AK, Zlebnik NE, Harris AC, Carroll ME (2015) Intracranial self-stimulation reward thresholds during morphine withdrawal in rats bred for high (HiS) and low (LoS) saccharin intake. Brain Res. 2015 Jan 9. pii: S0006-8993(15)00007-4. doi: 10.1016/j.brainres.2015.01.004.
Zlebnik NE, Hedges VL, Carroll ME, Meisel RL. (2014) Chronic wheel running affects cocaine-induced c-Fos expression in brain reward areas in rats. Behav Brain Res. 261:71-8
Regier PS, Claxton AB, Zlebnik NE, Carroll ME. Cocaine-, caffeine-, and stress-evoked cocaine reinstatement in high vs. low impulsive rats: treatment with allopregnanolone. Drug Alcohol Depend. 2014 Oct 1;143:58-64.
Zlebnik NE, Saykao AT, Carroll ME. Effects of combined exercise and progesterone treatments on cocaine seeking in male and female rats. Psychopharmacology (Berl). 2014 Sep;231(18):3787-98.
Zlebnik NE, Carroll ME. Effects of the combination of wheel running and atomoxetine on cue- and cocaine-primed reinstatement in rats selected for high or low impulsivity. Psychopharmacology (Berl). 2014 Sep 26;. [Epub ahead of print]
Zlebnik NE, Brimijoin S, Gao Y, Saykao AT, Parks RJ, Carroll ME. Long-Term Reduction of Cocaine Self-Administration in Rats Treated with Adenoviral Vector-Delivered Cocaine Hydrolase: Evidence for Enzymatic Activity. Neuropsychopharmacology. 2014 Jan 10;.
Holtz NA, Anker JJ, Regier PS, Claxton A, Carroll ME. Cocaine self-administration punished by i.v. histamine in rat models of high and low drug abuse vulnerability: effects of saccharin preference, impulsivity, and sex. Physiol Behav. 2013 Oct 2;122:32-8.
Anker JJ, Brimijoin S, Gao Y, Geng L, Zlebnik NE, Parks RJ, Carroll ME. Cocaine Hydrolase Encoded in Viral Vector Blocks the Reinstatement of Cocaine Seeking in Rats for 6 Months. Biol Psychiatry. 2011 Dec 29.
Holtz NA, Carroll ME. Baclofen has opposite effects on escalation of cocaine self-administration: increased intake in rats selectively bred for high (HiS) saccharin intake and decreased intake in those selected for low (LoS) saccharin intake. Pharmacol Biochem Behav. 2011 Dec;100(2):275-83.
Holtz NA, Lozama A, Prisinzano TE, Carroll ME. Reinstatement of methamphetamine seeking in male and female rats treated with modafinil and allopregnanolone. Drug Alcohol Depend. 2012 Jan 1;120(1-3):233-7.
Anker JJ, Carroll ME. Females are more vulnerable to drug abuse than males: evidence from preclinical studies and the role of ovarian hormones. Curr Top Behav Neurosci. 2011;8:73-96.
Anker JJ, Carroll ME. Adolescent nicotine exposure sensitizes cue-induced reinstatement of cocaine seeking in rats bred for high and low saccharin intake. Drug Alcohol Depend. 2011 Oct 1;118(1):68-72.
Anker JJ, Zlebnik NE, Navin SF, Carroll ME. Responding during signaled availability and nonavailability of iv cocaine and food in rats: age and sex differences. Psychopharmacology (Berl). 2011 Jun;215(4):785-99.
Carroll ME, Gao Y, Brimijoin S, Anker JJ. Effects of cocaine hydrolase on cocaine self-administration under a PR schedule and during extended access (escalation) in rats. Psychopharmacology (Berl). 2011 Feb;213(4):817-29.
Anker JJ, Zlebnik NE, Carroll ME. Differential effects of allopregnanolone on the escalation of cocaine self-administration and sucrose intake in female rats.Psychopharmacology (Berl). 2010 Oct;212(3):419-29.
Anker JJ, Carroll ME. The role of progestins in the behavioral effects of cocaine and other drugs of abuse: human and animal research. Neurosci Biobehav Rev. 2010 Nov;35(2):315-33.
Zlebnik NE, Anker JJ, Gliddon LA, Carroll ME. Reduction of extinction and reinstatement of cocaine seeking by wheel running in female rats. Psychopharmacology (Berl). 2010 Mar;209(1):113-25.
Anker JJ, Carroll ME. Sex differences in the effects of allopregnanolone on yohimbine-induced reinstatement of cocaine seeking in rats. Drug Alcohol Depend. 2010 Mar 1;107(2-3):264-7.
Anker JJ, Carroll ME. Reinstatement of cocaine seeking induced by drugs, cues, and stress in adolescent and adult rats. Psychopharmacology (Berl). 2010 Feb;208(2):211-22.
Carroll ME, Anker JJ. Sex differences and ovarian hormones in animal models of drug dependence. Horm Behav. 2010 Jun;58(1):44-56.
Current Graduate Students:
Natalie Zlebnik (Neuroscience, University of Minnesota).
Former Graduate Students:
Erin Larson (Ph.D. 2006, Neuroscience, University of Minnesota).