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Poulos AM, Reger M, Mehta N, Zhuravka I, Sterlace SS, Gannam C, Hovda DA, Giza CC, Fanselow M. Amnesia for early life stress does not preclude the adult development of posttraumatic stress disorder symptoms in rats. Biol Psychiatry 2014; 76:306-14. [PMID: 24231200 PMCID: PMC3984614 DOI: 10.1016/j.biopsych.2013.10.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/11/2013] [Accepted: 10/03/2013] [Indexed: 01/28/2023]
Abstract
BACKGROUND Traumatic experience can result in life-long changes in the ability to cope with future stressors and emotionally salient events. These experiences, particularly during early development, are a significant risk factor for later life anxiety disorders such as posttraumatic stress disorder (PTSD). However, because traumatic experience typically results in strong episodic memories, it is not known whether such long-term memories are necessary for particular features of PTSD, such as enhanced fear and anxiety. Here, we used a fear conditioning procedure in juvenile rats before maturation of the neural systems supporting declarative memory to assess the necessity of early memory to the later life development of PTSD-related symptoms. METHODS Nineteen-day old rats were exposed to unpredictable and inescapable footshocks, and fear memory for the shock context was assessed during adulthood. Thereafter, adult animals were either exposed to single-trial fear conditioning or elevated plus maze or sacrificed for basal diurnal corticosterone and quantification of neuronal glucocorticoid and neuropeptide Y receptors. RESULTS Early trauma exposed rats displayed stereotypic footshock reactivity, yet by adulthood, hippocampus-dependent contextual fear-related memory was absent. However, adult rats showed sensitized fear learning, aberrant basal circadian fluctuations of corticosterone, increased amygdalar glucocorticoid receptors, decreased time spent in the open arm of an elevated plus maze, and an odor aversion associated with early-life footshocks. CONCLUSIONS These results suggest that traumatic experience during developmental periods of hippocampal immaturity can promote lifelong changes in symptoms and neuropathology associated with human PTSD, even if there is no explicit memory of the early trauma.
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Affiliation(s)
- Andrew M. Poulos
- University of California, Los Angeles, Los Angeles, California, United States of America,Department of Psychology,UCLA Behavioral Testing Core, Brain Research Institute
| | - Maxine Reger
- University of California, Los Angeles, Los Angeles, California, United States of America,Department of Psychology,UCLA Brain Injury Research Center, Department of Neurosurgery, David Geffen School of Medicine
| | - Nehali Mehta
- University of California, Los Angeles, Los Angeles, California, United States of America,Department of Psychology
| | - Irina Zhuravka
- University of California, Los Angeles, Los Angeles, California, United States of America,Department of Psychology,UCLA Behavioral Testing Core, Brain Research Institute
| | - Sarah S. Sterlace
- University of California, Los Angeles, Los Angeles, California, United States of America,Department of Psychology
| | - Camille Gannam
- University of California, Los Angeles, Los Angeles, California, United States of America,Department of Psychology
| | - David A. Hovda
- University of California, Los Angeles, Los Angeles, California, United States of America,UCLA Brain Injury Research Center, Department of Neurosurgery, David Geffen School of Medicine
| | - Christopher C. Giza
- University of California, Los Angeles, Los Angeles, California, United States of America,UCLA Brain Injury Research Center, Department of Neurosurgery, David Geffen School of Medicine,Department of Pediatrics, Division of Pediatric Neurology, Mattel Children’s Hospital; and Department of Medical and Molecular Pharmacology
| | - Michael Fanselow
- University of California, Los Angeles, Los Angeles, California, United States of America,Department of Psychology,UCLA Behavioral Testing Core, Brain Research Institute,Department of Psychiatry and Biobehavioral Sciences, UCLA Integrative Center for Learning and Memory
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Hurwitz ZE, Cobuzzi JL, Merluzzi AP, Wetzell B, Riley AL. Prepubertal Fischer 344 rats display stronger morphine-induced taste avoidance than prepubertal Lewis rats. Dev Psychobiol 2013; 56:979-88. [PMID: 24166592 DOI: 10.1002/dev.21176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 09/30/2013] [Indexed: 12/15/2022]
Abstract
The present report asked if the previously reported differences in morphine-induced conditioned taste avoidance between adult F344 and LEW rats (F344 > LEW) are also evident in prepubescence (early adolescence). To assess this possibility, adult (Experiment 1) and prepubertal (Experiment 2) F344 and LEW rats were assessed for their ability to acquire morphine-induced taste avoidance (0, 3.2, 10, or 18 mg/kg) in a modified taste avoidance procedure. In each experiment, rats of both strains were given repeated pairings of saccharin and morphine followed by a final two-bottle avoidance test. Adult and prepubertal F344 subjects displayed a more rapid acquisition of the avoidance response as well as stronger suppression of consumption than their LEW counterparts. These data suggest the strains differ in their sensitivity to the aversive effects of morphine and that this differential sensitivity is evident early in development and is developmentally stable. The basis for these strain differences in morphine-induced avoidance was discussed.
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Affiliation(s)
- Zachary E Hurwitz
- Psychopharmacology Laboratory, Department of Psychology, American University, 4400 Mass. Ave., NW, Washington, DC, 20016.
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Merluzzi AP, Hurwitz ZE, Briscione MA, Cobuzzi JL, Wetzell B, Rice KC, Riley AL. Age-dependent MDPV-induced taste aversions and thermoregulation in adolescent and adult rats. Dev Psychobiol 2013; 56:943-54. [PMID: 24122728 DOI: 10.1002/dev.21171] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 08/30/2013] [Indexed: 12/17/2022]
Abstract
Adolescent rats are more sensitive to the rewarding and less sensitive to the aversive properties of various drugs of abuse than their adult counterparts. Given a nationwide increase in use of "bath salts," the present experiment employed the conditioned taste aversion procedure to assess the aversive effects of 3,4-methylenedioxypyrovalerone (MDPV; 0, 1.0, 1.8, or 3.2 mg/kg), a common constituent in "bath salts," in adult and adolescent rats. As similar drugs induce thermoregulatory changes in rats, temperature was recorded following MDPV administration to assess if thermoregulatory changes were related to taste aversion conditioning. Both age groups acquired taste aversions, although these aversions were weaker and developed at a slower rate in the adolescent subjects. Adolescents increased and adults decreased body temperature following MDPV administration with no correlation to aversions. The relative insensitivity of adolescents to the aversive effects of MDPV suggests that MDPV may confer an increased risk in this population.
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Affiliation(s)
- Andrew P Merluzzi
- Psychopharmacology Laboratory, Department of Psychology, American University, 4400 Mass. Ave., NW, Washington, DC, 20016.
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Cobuzzi JL, Siletti KA, Hurwitz ZE, Wetzell B, Baumann MH, Riley AL. Age differences in (±) 3,4-methylenedioxymethamphetamine (MDMA)-induced conditioned taste aversions and monoaminergic levels. Dev Psychobiol 2013; 56:635-46. [PMID: 23775255 DOI: 10.1002/dev.21132] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 04/12/2013] [Indexed: 11/07/2022]
Abstract
Preclinical work indicates that adolescent rats appear more sensitive to the rewarding effects and less sensitive to the aversive effects of abused drugs. The present investigation utilized the conditioned taste aversion (CTA) design to measure the relative aversive effects of (±)3,4-methylenedioxymethamphetamine (MDMA; 0, 1.0, 1.8, or 3.2 mg/kg) in adolescent and adult Sprague-Dawley rats. After behavioral testing was complete, monoamine and associated metabolite levels in discrete brain regions were quantified using high-performance liquid chromatography coupled to electrochemical detection (HPLC-ECD) to determine if adolescent animals displayed a different neurochemical profile than did adult animals after being exposed to subcutaneous low doses of MDMA. Adolescent rats displayed less robust MDMA-induced taste aversions than adults during acquisition and on a final two-bottle aversion test. MDMA at these doses had no consistent effect on monoamine levels in either age group, although levels did vary with age. The relative insensitivity of adolescents to MDMA's aversive effects may engender an increased vulnerability to MDMA abuse in this specific population.
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Affiliation(s)
- Jennifer L Cobuzzi
- Psychopharmacology Laboratory, Department of Psychology, American University, 4400 Massachusetts Ave NW, Washington, DC, 20016
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Hurwitz ZE, Merluzzi AP, Riley AL. Age-dependent differences in morphine-induced taste aversions. Dev Psychobiol 2012; 55:415-28. [DOI: 10.1002/dev.21046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 04/17/2012] [Indexed: 11/08/2022]
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Grakalic I, Riley AL. Asymmetric serial interactions between ethanol and cocaine in taste aversion learning. Pharmacol Biochem Behav 2002; 73:787-95. [PMID: 12213523 DOI: 10.1016/s0091-3057(02)00905-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Although the interaction between ethanol and cocaine is well documented, it has generally been limited to situations in which the two drugs are given concurrently. Little exists on the interaction between ethanol and cocaine when one drug is given prior to the other. In Experiment 1, female Long-Evans rats were given five exposures to ethanol (2 g/kg ip) or vehicle prior to taste aversion conditioning with cocaine (32 mg/kg sc) for a total of five conditioning trials. In Experiment 2, rats were given five exposures to cocaine (32 mg/kg sc) or vehicle prior to taste aversion conditioning with ethanol (2 g/kg ip) for a total of five conditioning trials. Ethanol-preexposed, cocaine-conditioned animals (Experiment 1) displayed attenuated aversions to the cocaine-associated solution, drinking significantly greater amounts of saccharin than vehicle-preexposed, conditioned subjects. Conversely, cocaine-preexposed, ethanol-conditioned animals (Experiment 2) displayed robust aversions to the ethanol-associated solution, drinking levels comparable to those consumed by vehicle-preexposed, conditioned subjects and drinking significantly less than controls. Although the basis for these asymmetric effects is not known, they may have implications for abuse vulnerability in that drug history may impact subsequent drug toxicity that, in turn, may alter drug acceptability.
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Affiliation(s)
- Ivana Grakalic
- Psychopharmacology Laboratory, Department of Psychology, American University, Washington, DC 20016, USA.
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Kunin D, Gaskin S, Borjas MB, Smith BR, Amit Z. Differences in locomotor response to an inescapable novel environment predict sensitivity to aversive effects of amphetamine. Behav Pharmacol 2001; 12:61-7. [PMID: 11270513 DOI: 10.1097/00008877-200102000-00007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Differences in locomotor response to an inescapable novel environment have previously been shown to predict sensitivity to amphetamine reward, where high responders (HR), compared to low responders (LR), showed greater initial sensitivity to amphetamine self-administration. The present experiments sought to extend these findings and assessed the relationship between locomotor response to an inescapable novel environment and conditioned taste aversion (CTA) with amphetamine and lithium chloride (LiCl). Male Sprague-Dawley rats were tested for their locomotor response to an inescapable novel environment and divided into high (HR) or low (LR) responders, based on whether their locomotor scores were above or below the median activity level of the subject sample. After several days, the animals were tested in a CTA procedure and conditioned with either amphetamine or lithium chloride. Compared to HR rats, LR rats showed greater sensitivity to amphetamine CTA at the doses tested. In contrast, the results with LiCl showed no relationship between locomotor response to an inescapable novel environment and CTA. Taken together, the present results suggest that LR, compared to HR, rats show less sensitivity to the rewarding effects of amphetamine because they are more sensitive to aversive effects of amphetamine, as reflected in CTA. In contrast, HR rats display less sensitivity to aversive effects of amphetamine, which may explain their greater propensity to self-administer amphetamine.
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Affiliation(s)
- D Kunin
- Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, Montreal, Quebec, Canada.
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Gomez F, Leo NA, Grigson PS. Morphine-induced suppression of saccharin intake is correlated with elevated corticosterone levels. Brain Res 2000; 863:52-8. [PMID: 10773192 DOI: 10.1016/s0006-8993(00)02093-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Rats suppress intake of a saccharin conditioned stimulus (CS) when paired with a drug of abuse. This phenomenon, however, is not uniform across all subjects and is greater following exposure to stress and in animals that more readily self-administer drugs of abuse. The present study was designed to examine these individual differences in intake suppression following seven saccharin-morphine pairings. Plasma corticosterone also was evaluated both before and after conditioning in order to determine whether the magnitude of CS suppression is, or is not, related to circulating corticosterone levels. The findings indicated that, while all rats were exposed to the same number of saccharin-morphine pairings, only half of these animals actually suppressed intake of the saccharin CS. Moreover, the results showed that greater suppression of CS intake was associated with higher corticosterone levels at test (r=-0.84, P<0.0001). Taken together, the results demonstrate that individual differences affect not only the reduction in CS intake following taste-drug pairings, but also the associated cue-induced elevation in circulating corticosterone.
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Affiliation(s)
- F Gomez
- Department of Behavioral Science, Penn State College of Medicine, Hershey, PA, USA.
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Bowers WJ, Attiast E, Amit Z. Stress enhances the response to reward reduction but not food-motivated responding. Physiol Behav 1999; 67:777-82. [PMID: 10604850 DOI: 10.1016/s0031-9384(99)00129-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effect of a single exposure to foot shock stress on runway responding for food reinforcement was assessed in animals trained and tested with the same or changed reinforcement magnitude. Foot shock (30 1-s shocks, 1.0 mA) exerted no impact on runway responding in animals trained and tested with the same level of reinforcement magnitude regardless of the absolute level of reinforcement magnitude (i.e., either 15 pellets or 1 pellet). Similarly, foot shock exerted no impact on runway responding in animals trained with a small magnitude of reinforcement but tested with an increased magnitude of reinforcement. In contrast, foot shock enhanced the increase in runway latencies produced by a reduction in reinforcement magnitude. Because reductions in reinforcement magnitude are known to be aversive for animals, these data indicate that foot shock stress can alter the behavioral response to an aversive stimulus without disrupting behavioral responding for an appetitive reinforcer. They also suggest that stressor-induced alterations in appetitively motivated behaviors may be secondary to alterations in sensitivity to subtle aversive stimuli rather than by directly altering appetitive motivation.
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Affiliation(s)
- W J Bowers
- Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Quebec, Canada
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Riley AL, Simpson GR. Cocaine preexposure fails to sensitize the acquisition of cocaine-induced taste aversions. Pharmacol Biochem Behav 1999; 63:193-9. [PMID: 10371647 DOI: 10.1016/s0091-3057(98)00265-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In two separate experiments, rats were given either an intraperitoneal (IP) injection of 10 mg/kg cocaine once a day for 10 consecutive days (Experiment 1) or a single IP injection of 40 mg/kg of cocaine (Experiment 2) prior to receiving repeated pairings of a novel saccharin solution with cocaine (32 mg/ kg; subcutaneous; SC). Although vehicle-preexposed subjects given saccharin-cocaine pairings readily acquired an aversion to the cocaine-associated saccharin solution, subjects preexposed to cocaine (whether 10 times or only once) displayed a retarded acquisition of the aversion. That is, cocaine preexposure attenuated the acquisition of cocaine-induced taste aversions. There was no difference in the degree of attenuation between the two preexposure conditions. Thus, under conditions that are effective in inducing sensitization within other behavioral preparations there was no evidence of sensitized cocaine-induced taste aversions. The results from the present investigation are similar to reports from this laboratory and others demonstrating that preexposure to cocaine, as with a range of other psychoactive drugs, results in weaker taste aversions. The basis for the attenuating effects of cocaine preexposure was discussed in terms of an adaptation to the aversive effects of cocaine.
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Affiliation(s)
- A L Riley
- Department of Psychology, American University, Washington, DC 20016, USA
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