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Vassoler FM, Toorie AM, Byrnes EM. Increased cocaine reward in offspring of females exposed to morphine during adolescence. Psychopharmacology (Berl) 2019; 236:1261-1272. [PMID: 30506236 DOI: 10.1007/s00213-018-5132-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 11/22/2018] [Indexed: 10/27/2022]
Abstract
RATIONALE A growing body of evidence demonstrates that environmental exposures can impact the physiology and behavior of subsequent generations. We have previously demonstrated reduced morphine self-administration in the F1 and F2 offspring of female rats exposed to morphine during adolescence. OBJECTIVES The current study was designed to determine whether attenuated self-administration for a substance not in the opioid class is also observed in the F1 progeny of adolescent morphine exposed females. METHODS Female adolescent rats were administered morphine at increasing doses for 10 days (P30-39). Females then remained drug free for at least 3 weeks prior to mating with drug-naïve males. As adults, male and female offspring (F1 animals) were tested for cocaine self-administration acquisition, progressive ratio, extinction, and reinstatement. In addition, β-endorphin peptide levels were measured in the nucleus accumbens (NAc) of behaviorally experienced animals following reinstatement and in behaviorally naïve littermates after acute cocaine (0 or 10 mg/kg, i.p.). Proopiomelanocortin, the polypeptide that is cleaved to produce β-endorphin, as well as β-endorphin, was examined in the arcuate nucleus of the hypothalamus and the nucleus accumbens, respectively. Finally, corticosterone was measured following acute cocaine. RESULTS While no differences were observed during the cocaine acquisition phase (FR-1 and FR-5 schedules), under a PR schedule, Mor-F1 animals (both males and females) had increased motivated responding for cocaine. In addition, Mor-F1 males demonstrated enhanced reinstatement compared to Sal-F1 males. In Mor-F1 males, an acute injection of cocaine (10 mg/kg, i.p.) decreased β-endorphin levels in the NAc compared to a saline injection while acute cocaine increased β-endorphin in the NAc in Sal-F1 males compared to saline injection. Following acute cocaine, Mor-F1 males had significantly lower levels of β-endorphin in the Nac compared to Sal-F1 males. Additionally, β-endorphin levels in the nucleus accumbens were negatively correlated with reinstatement behavior only in Mor-F1 males. Levels of POMC in the arcuate nucleus were elevated in Mor-F1 males compared to Sal-F1 males, a main effect driven primarily by POMC levels in the acute cocaine condition. These changes were not observed in Mor-F1 females. Finally, plasma corticosterone was increased in Mor-F1 males regardless of acute injection while Mor-F1 females displayed increased corticosterone in response to acute cocaine. CONCLUSIONS These data indicate that morphine prior to conception increases the rewarding effects of cocaine in male and female offspring. In addition, sex-specific alterations in endogenous opioids and hypothalamic physiology were observed.
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Affiliation(s)
- Fair M Vassoler
- Tufts University Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA, 01536, USA.
| | - Anika M Toorie
- Tufts University Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA, 01536, USA
| | - Elizabeth M Byrnes
- Tufts University Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA, 01536, USA
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Yadid G, Ahdoot-Levi H, Bareli T, Maayan R, Weizman A. Dehydroepiandrosterone and Addiction. VITAMINS AND HORMONES 2018; 108:385-412. [PMID: 30029736 DOI: 10.1016/bs.vh.2018.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Drug addiction has a great negative influence on society, both social and economic burden. It was widely thought that addicts could choose to stop using drugs if only they had some self-control and principles. Nowadays, science has changed this view, defining drug addiction as a complex brain disease that affects behavior in many ways, both biological and psychological. Currently there is no ground-breaking reliable treatment for drug addiction. For more than a decade we are researching an alternative approach for intervention with drug craving and relapse to its usage, using DHEA, a well-being and antiaging food supplement. In this chapter we navigate through the significant therapeutic effect of DHEA on the brain circuits that control addiction and on behavioral performance both in animal models and addicts. We suggest that an integrative program of add-on DHEA treatment may further enable to dynamically evaluate the progress of rehabilitation of an individual patient, in a comprehensive assessment. Such a program may boost and support the detoxification and rehabilitation process, and help patients regain a normal life in a shorter amount of time.
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Affiliation(s)
- Gal Yadid
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel; The Leslie and Susan Gonda (Goldschmied) Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat Gan, Israel.
| | - Hadas Ahdoot-Levi
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Tzofnat Bareli
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Rachel Maayan
- Laboratory of Biological Psychiatry, Felsenstein Medical Research Center, Research Unit, Petah Tikva, Israel
| | - Abraham Weizman
- Laboratory of Biological Psychiatry, Felsenstein Medical Research Center, Research Unit, Petah Tikva, Israel; Geha Mental Health Center, Tel-Aviv University, Tel Aviv, Israel
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3
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Simola N, Paci E, Serra M, Costa G, Morelli M. Modulation of Rat 50-kHz Ultrasonic Vocalizations by Glucocorticoid Signaling: Possible Relevance to Reward and Motivation. Int J Neuropsychopharmacol 2017; 21:73-83. [PMID: 29182715 PMCID: PMC5795343 DOI: 10.1093/ijnp/pyx106] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 11/13/2017] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Rats emit 50-kHz ultrasonic vocalizations (USVs) to communicate positive emotional states, and these USVs are increasingly being investigated in preclinical studies on reward and motivation. Although it is the activation of dopamine receptors that initiates the emission of 50-kHz USVs, non-dopaminergic mechanisms may modulate calling in the 50 kHz frequency band. To further elucidate these mechanisms, the present study investigated whether the pharmacological manipulation of glucocorticoid signaling influenced calling. METHODS Rats were administered corticosterone (1-5 mg/kg, s.c.), the glucocorticoid receptor antagonist mifepristone (40 or 100 mg/kg, s.c.), or the corticosterone synthesis inhibitor metyrapone (50 or 100 mg/kg, i.p.). The effects of these drugs on calling initiation and on calling recorded during nonaggressive social contacts or after the administration of amphetamine (0.25 or 1 mg/kg, i.p.) were then evaluated. RESULTS Corticosterone failed to initiate the emission of 50-kHz USVs and did not influence pro-social and amphetamine-stimulated calling. Similarly, mifepristone and metyrapone did not initiate calling. However, metyrapone suppressed pro-social calling and calling stimulated by a moderate dose (1 mg/kg, i.p.) of amphetamine. Conversely, mifepristone attenuated calling stimulated by a low (0.25 mg/kg, i.p.), but not moderate (1 mg/kg, i.p.), dose of amphetamine and had no influence on pro-social calling. CONCLUSIONS The present results demonstrate that glucocorticoid signaling modulates calling in the 50 kHz frequency band only in certain conditions and suggest that mechanisms different from the inhibition of corticosterone synthesis may participate in the suppression of calling by metyrapone.
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Affiliation(s)
- Nicola Simola
- Department of Biomedical Sciences, Section of Neuropsychopharmacology, University of Cagliari, Cagliari, Italy,National Institute of Neuroscience, University of Cagliari, Cagliari, Italy,Correspondence: Nicola Simola, PhD, Department of Biomedical Sciences, Section of Neuropsychopharmacology, University of Cagliari, Via Ospedale, 72, 09124, Cagliari, Italy ()
| | - Elena Paci
- Department of Physiology, University of Bristol, Bristol, United Kingdom,Department of Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Marcello Serra
- Department of Biomedical Sciences, Section of Neuropsychopharmacology, University of Cagliari, Cagliari, Italy
| | - Giulia Costa
- Department of Biomedical Sciences, Section of Neuropsychopharmacology, University of Cagliari, Cagliari, Italy
| | - Micaela Morelli
- Department of Biomedical Sciences, Section of Neuropsychopharmacology, University of Cagliari, Cagliari, Italy,National Institute of Neuroscience, University of Cagliari, Cagliari, Italy,NCR, National Research Council of Italy, Neuroscience Institute, Cagliari, Italy
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4
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Keller CM, Breaux KN, Goeders NE. Effects of the combination of metyrapone and oxazepam on cocaine-induced increases in corticosterone in the medial prefrontal cortex and nucleus accumbens. Psychoneuroendocrinology 2017; 77:75-83. [PMID: 28024272 DOI: 10.1016/j.psyneuen.2016.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 12/05/2016] [Accepted: 12/05/2016] [Indexed: 10/20/2022]
Abstract
We have previously demonstrated that a combination of drugs (i.e., metyrapone and oxazepam) known to attenuate HPA-axis activity effectively decreases cocaine self-administration and cue reactivity in rats. However, we did not find changes in plasma corticosterone that matched the behavioral effects we observed, indicating that a different mechanism of action must be involved. Therefore, we hypothesized that the combination of metyrapone and oxazepam attenuates cocaine taking and seeking by decreasing cocaine-induced increases in corticosterone in the brain. Male rats were implanted with guide cannulae targeting the medial prefrontal cortex or nucleus accumbens. After the rats recovered from surgery, the microdialysis session was conducted. Rats were housed in the experimental chamber and the dialysis probes inserted into the guide cannulae the night before the session. The following day, dialysate samples were collected over a five-hour session. Baseline samples were collected for the first two hours, every 20min. Samples were then collected following administration of cocaine (15mg/kg, ip). Before injections of cocaine, rats were pretreated with either vehicle or the combination of metyrapone (50mg/kg, ip) and oxazepam (10mg/kg, ip). The administration of cocaine resulted in an increase in corticosterone in the medial prefrontal cortex following vehicle pretreatment, which was not observed in the nucleus accumbens. This cocaine-induced increase in corticosterone was attenuated by metyrapone/oxazepam. Reducing cocaine-induced increases in corticosterone in the medial prefrontal cortex might represent a novel mechanism through which the combination of metyrapone/oxazepam produces its behavioral effects.
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Affiliation(s)
- Courtney M Keller
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, LA 71130, United States.
| | - Kelly N Breaux
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, LA 71130, United States
| | - Nicholas E Goeders
- Department of Pharmacology, Toxicology & Neuroscience, LSU Health Sciences Center, Shreveport, LA 71130, United States
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Schmidt HD, Mietlicki-Baase EG, Ige KY, Maurer JJ, Reiner DJ, Zimmer DJ, Van Nest DS, Guercio LA, Wimmer ME, Olivos DR, De Jonghe BC, Hayes MR. Glucagon-Like Peptide-1 Receptor Activation in the Ventral Tegmental Area Decreases the Reinforcing Efficacy of Cocaine. Neuropsychopharmacology 2016; 41:1917-28. [PMID: 26675243 PMCID: PMC4869061 DOI: 10.1038/npp.2015.362] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 12/11/2015] [Accepted: 12/11/2015] [Indexed: 01/26/2023]
Abstract
Cocaine addiction continues to be a significant public health problem for which there are currently no effective FDA-approved treatments. Thus, there is a clear need to identify and develop novel pharmacotherapies for cocaine addiction. Recent evidence indicates that activation of glucagon-like peptide-1 (GLP-1) receptors in the ventral tegmental area (VTA) reduces intake of highly palatable food. As the neural circuits and neurobiological mechanisms underlying drug taking overlap to some degree with those regulating food intake, these findings suggest that activation of central GLP-1 receptors may also attenuate cocaine taking. Here, we show that intra-VTA administration of the GLP-1 receptor agonist exendin-4 (0.05 μg) significantly reduced cocaine, but not sucrose, self-administration in rats. We also demonstrate that cocaine taking is associated with elevated plasma corticosterone levels and that systemic infusion of cocaine activates GLP-1-expressing neurons in the nucleus tractus solitarius (NTS), a hindbrain nucleus that projects monosynaptically to the VTA. To determine the potential mechanisms by which cocaine activates NTS GLP-1-expressing neurons, we microinjected corticosterone (0.5 μg) directly into the hindbrain fourth ventricle. Intraventricular corticosterone attenuated cocaine self-administration and this effect was blocked in animals pretreated with the GLP-1 receptor antagonist exendin-(9-39) (10 μg) in the VTA. Finally, AAV-shRNA-mediated knockdown of VTA GLP-1 receptors was sufficient to augment cocaine self-administration. Taken together, these findings indicate that increased activation of NTS GLP-1-expressing neurons by corticosterone may represent a homeostatic response to cocaine taking, thereby reducing the reinforcing efficacy of cocaine. Therefore, central GLP-1 receptors may represent a novel target for cocaine addiction pharmacotherapies.
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Affiliation(s)
- Heath D Schmidt
- Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA,Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, USA,Department of Biobehavioral Health Sciences, School of Nursing, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, 125 South 31st Street, Philadelphia, PA 19104, USA, Tel: +1 215 573 8291, Fax: +1 215 573 7605, E-mail:
| | - Elizabeth G Mietlicki-Baase
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kelsey Y Ige
- Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - John J Maurer
- Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David J Reiner
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Derek J Zimmer
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Duncan S Van Nest
- Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Leonardo A Guercio
- Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mathieu E Wimmer
- Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Diana R Olivos
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Bart C De Jonghe
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, USA
| | - Matthew R Hayes
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, PA, USA,Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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6
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Howland RH. Oxazepam for the Treatment of Substance Abuse and Depression: Is it Appropriate? J Psychosoc Nurs Ment Health Serv 2016; 54:21-4. [DOI: 10.3928/02793695-20160420-03] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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7
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Maayan R, Hirsh L, Yadid G, Weizman A. Dehydroepiandrosterone Attenuates Cocaine-Seeking Behaviour Independently of Corticosterone Fluctuations. J Neuroendocrinol 2015; 27:819-26. [PMID: 26309224 DOI: 10.1111/jne.12322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 08/20/2015] [Accepted: 08/22/2015] [Indexed: 11/26/2022]
Abstract
The neurosteroid dehydroepiandrosterone (DHEA) is involved in the pathophysiology of several psychiatric disorders, including cocaine addiction. We have previously shown that DHEA attenuates cocaine-seeking behaviour, and also that DHEA decreases corticosterone (CORT) levels in plasma and the prefrontal cortex. Previous studies have found that rats demonstrate cocaine-seeking behaviour only when the level of CORT reaches a minimum threshold. In the present study, we investigated whether the attenuating effect of DHEA on cocaine seeking is a result of it reducing CORT levels rather than a result of any unique neurosteroid properties. Rats received either daily DHEA injections (2 mg/kg, i.p.) alone, daily DHEA (2 mg/kg, i.p.) with CORT infusion (to maintain stable basal levels of CORT; 15 mg/kg, s.c.) or vehicle (i.p.) as control, throughout self-administration training and extinction sessions. We found that both DHEA-treated and DHEA + CORT-treated groups showed a significantly lower number of active lever presses compared to controls throughout training and extinction sessions, as well as at cocaine-primed reinstatement. DHEA-treated rats showed lower CORT levels throughout the experimental phases compared to DHEA + CORT-treated and control rats. Additionally, we show that DHEA administered to cocaine-trained rats throughout extinction sessions, or immediately before reinstatement, attenuated cocaine seeking. These findings indicate that DHEA attenuates cocaine-seeking behaviour independently of fluctuations in CORT levels.
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Affiliation(s)
- R Maayan
- The Laboratory of Biological Psychiatry, Felsenstein Medical Research Center and Sackler Faculty of Medicine, Tel Aviv University, Petah Tikva, Israel
| | - L Hirsh
- Leslie and Gonda (Goldschmied) Multidisciplinary Brain Research Center, Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - G Yadid
- Leslie and Gonda (Goldschmied) Multidisciplinary Brain Research Center, Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - A Weizman
- The Laboratory of Biological Psychiatry, Felsenstein Medical Research Center and Sackler Faculty of Medicine, Tel Aviv University, Petah Tikva, Israel
- Geha Mental Health Center, Petah Tikva, Israel
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Schmoutz CD, Guerin GF, Runyon SP, Dhungana S, Goeders NE. A therapeutic combination of metyrapone and oxazepam increases brain levels of GABA-active neurosteroids and decreases cocaine self-administration in male rats. Behav Brain Res 2015; 291:108-111. [DOI: 10.1016/j.bbr.2015.05.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/12/2015] [Indexed: 10/23/2022]
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Hofford RS, Prendergast MA, Bardo MT. Pharmacological manipulation of glucocorticoid receptors differentially affects cocaine self-administration in environmentally enriched and isolated rats. Behav Brain Res 2015; 283:196-202. [PMID: 25655510 PMCID: PMC4351170 DOI: 10.1016/j.bbr.2015.01.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 01/20/2015] [Accepted: 01/23/2015] [Indexed: 02/01/2023]
Abstract
Social isolation rearing (isolated condition, IC) is used as a model of early life stress in rodents. Rats raised in this condition are often compared to rats raised in an environmentally enriched condition (EC). However, EC rats are repeatedly exposed to forced novelty, another classic stressor in rodents. These studies explored the relationship between cocaine self-administration and glucocorticoid receptor (GR) activation and measured total levels of GR protein in reward-related brain regions (medial prefrontal cortex, orbitofrontal cortex, nucleus accumbens, amygdala) in rats chronically exposed to these conditions. For experiment 1, rats were housed in EC or IC and were then trained to self-administer cocaine. Rats raised in these housing conditions were tested for their cocaine responding after pretreatment with the GR antagonist, RU486, or the GR agonist, corticosterone (CORT). For experiment 2, levels of GR from EC and IC rats were measured in brain regions implicated in drug abuse using Western blot analysis. Pretreatment with RU486 (20 mg/kg) decreased responding for a low unit dose of cocaine (0.03 mg/kg/infusion) in EC rats only. IC rats were unaffected by RU486 pretreatment, but earned significantly more cocaine than EC rats after pretreatment with CORT (10 mg/kg). No difference in GR expression was found between EC and IC rats in any brain area examined. These results, along with previous literature, suggest that enrichment enhances responsivity of the HPA axis related to cocaine reinforcement, but this effect is unlikely due simply to differential baseline GR expression in areas implicated in drug abuse.
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Affiliation(s)
- Rebecca S Hofford
- Department of Psychology, University of Kentucky, Lexington, KY, USA.
| | | | - Michael T Bardo
- Department of Psychology, University of Kentucky, Lexington, KY, USA; Center for Drug Abuse Research Translation, University of Kentucky, Lexington, KY, USA
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Role of GABA-active neurosteroids in the efficacy of metyrapone against cocaine addiction. Behav Brain Res 2014; 271:269-76. [PMID: 24959859 DOI: 10.1016/j.bbr.2014.06.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/09/2014] [Accepted: 06/16/2014] [Indexed: 01/29/2023]
Abstract
Previous research has demonstrated a complicated role for stress and HPA axis activation in potentiating various cocaine-related behaviors in preclinical models of drug dependence. However, the investigation of several antiglucocorticoid therapies has yielded equivocal results in reducing cocaine-related behaviors, possibly because of varying mechanisms of actions. Specifically, research suggests that metyrapone (a corticosterone synthesis inhibitor) may reduce cocaine self-administration in rats via a nongenomic, extra-adrenal mechanism without altering plasma corticosterone. In the current experiments, male rats were trained to self-administer cocaine infusions and food pellets in a multiple, alternating schedule of reinforcement. Metyrapone pretreatment dose-dependently decreased cocaine self-administration as demonstrated previously. Pharmacological inhibition of neurosteroid production by finasteride had significant effects on cocaine self-administration, regardless of metyrapone pretreatment. However, metyrapone's effects on cocaine self-administration were significantly attenuated with bicuculline pretreatment, suggesting a role for GABA-active neurosteroids in cocaine-reinforced behaviors. In vitro binding data also confirmed that metyrapone does not selectively bind to GABA-related proteins. The results of these experiments support the hypothesis that metyrapone may increase neurosteroidogenesis to produce effects on cocaine-related behaviors.
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