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Cullity ER, Guérin AA, Madsen HB, Perry CJ, Kim JH. Insular cortex dopamine 1 and 2 receptors in methamphetamine conditioned place preference and aversion: Age and sex differences. NEUROANATOMY AND BEHAVIOUR 2021. [DOI: 10.35430/nab.2021.e24] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Rodent studies have proposed that adolescent susceptibility to substance use is at least partly due to adolescents experiencing reduced aversive effects of drugs compared to adults. We thus investigated methamphetamine (meth) conditioned place preference/aversion (CPP/CPA) in adolescent and adult mice in both sexes using a high dose of meth (3 mg/kg) or saline as controls. Mice tagged with green-fluorescent protein (GFP) at Drd1a or Drd2 were used so that dopamine receptor 1 (D1) and 2 (D2) expression within the insular cortex (insula) could be quantified. There are sex differences in how the density of D1+ and D2+ cells in the insula changes across adolescence that may be related to drug-seeking behaviors. Immunohistochemistry followed by stereology were used to quantify the density of cells with c-Fos and/or GFP in the insula. Unexpectedly, mice showed huge variability in behaviors including CPA, CPP, or no preference or aversion. Females were less likely to show CPP compared to males, but no age differences in behavior were observed. Conditioning with meth increased the number of D2 + cells co-labelled with c-Fos in adults but not in adolescents. D1:D2 ratio also sex- and age-dependently changed due to meth compared to saline. These findings suggest that reduced aversion to meth is unlikely an explanation for adolescent vulnerability to meth use. Sex- and age-specific expressions of insula D1 and D2 are changed by meth injections, which has implications for subsequent meth use.
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Affiliation(s)
- Ellen Rose Cullity
- Mental Health Theme, Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia
- The Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Australia
| | - Alexandre Arthur Guérin
- Mental Health Theme, Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia
- The Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Australia
| | - Heather Bronwyn Madsen
- Mental Health Theme, Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia
| | - Christina Jennifer Perry
- Mental Health Theme, Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia
- The Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Australia
| | - Jee Hyun Kim
- Mental Health Theme, Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia
- The Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Australia
- IMPACT – the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Deakin University, Geelong, VIC, Australia
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2
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Linton SR, Levita L. Potentiated perceptual neural responses to learned threat during Pavlovian fear acquisition and extinction in adolescents. Dev Sci 2021; 24:e13107. [PMID: 33817917 DOI: 10.1111/desc.13107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 01/31/2021] [Accepted: 02/24/2021] [Indexed: 11/30/2022]
Abstract
Adolescents' experience of heightened anxiety and increased vulnerability to develop anxiety disorders is believed to partly result from blunted fear extinction processes. However, whether this anxiety is mediated by adolescent-specific differences in perceptual responses to learned threat is not known. To investigate this, we used EEG to examine reinforcement-dependent changes in early visual event-related potentials in adolescents (N = 28, 13-14 years) and adults (N = 23, 25-26 years old) during a differential Pavlovian fear conditioning task, with one conditioned stimulus (CS+) paired with an aversive sound (unconditioned stimulus [US]) on 50% of trials, and another (CS-) never paired with the US. An immediate extinction phase followed, where both CSs were presented alone. We found age-dependent dissociations between explicit and implicit measures of fear learning. Specifically, both adolescents and adults demonstrated successful fear conditioning and extinction according to their explicit awareness of changes in CS contingencies and their evaluative CS ratings, and their differential skin conductance responses. However, for the first time we show age differences at the neural level in perceptual areas. Only adolescents showed greater visual P1 and N1 responses to the CS+ compared to the CS- during acquisition, a dissociation that for the N1 was maintained during extinction. We suggest that the adolescent perceptual hyper-responsivity to learned threat and blunted extinction reported here could be an adaptive mechanism to protect adolescents from harm. However, this hyper-responsivity may also confer greater vulnerability to experience pathological levels of anxiety at this developmental stage.
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Affiliation(s)
| | - Liat Levita
- Department of Psychology, University of Sheffield, Sheffield, UK
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3
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Kantak KM. Adolescent-onset vs. adult-onset cocaine use: Impact on cognitive functioning in animal models and opportunities for translation. Pharmacol Biochem Behav 2020; 196:172994. [PMID: 32659242 DOI: 10.1016/j.pbb.2020.172994] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/25/2020] [Accepted: 07/02/2020] [Indexed: 01/03/2023]
Abstract
Animal models are poised to make key contributions to the study of cognitive deficits associated with chronic cocaine use in people. Advantages of animal models include use of a longitudinal experimental design that can control for drug use history and onset-age, sex, drug consumption, and abstinence duration. Twenty-two studies were reviewed (13 in adult male rats, 5 in adolescent vs. adult male rats, 3 in adult male monkeys, and 1 in adult female monkeys), and it was demonstrated repeatedly that male animals with adult-onset cocaine self-administration exposure had impairments in sustained attention, decision making, stimulus-reward learning, working memory, and cognitive flexibility, but not habit learning and spatial learning and memory. These findings have translational relevance because adult cocaine users exhibit a similar range of cognitive deficits. In the limited number of studies available, male rats self-administering cocaine during adolescence were less susceptible than adults to impairment in cognitive flexibility, stimulus-reward learning, and decision making, but were more susceptible than adults to impairment in working memory, a finding also reported in the few studies performed in early-onset cocaine users. These findings suggest that animal models can help fill an unmet need for investigating important but yet-to-be-fully-addressed research questions in people. Research priorities include further investigation of differences between adolescents and adults as well as between males and females following chronic cocaine self-administration. A comprehensive understanding of the broad range of cognitive consequences of chronic cocaine use and the role of developmental plasticity can be of value for improving neuropsychological recovery efforts.
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Affiliation(s)
- Kathleen M Kantak
- Department of Psychological and Brain Sciences, Boston University, Boston, MA 02215, United States of America.
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Riley AL, Nelson KH, To P, López-Arnau R, Xu P, Wang D, Wang Y, Shen HW, Kuhn DM, Angoa-Perez M, Anneken JH, Muskiewicz D, Hall FS. Abuse potential and toxicity of the synthetic cathinones (i.e., “Bath salts”). Neurosci Biobehav Rev 2020; 110:150-173. [DOI: 10.1016/j.neubiorev.2018.07.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/14/2018] [Accepted: 07/24/2018] [Indexed: 01/22/2023]
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Corongiu S, Dessì C, Cadoni C. Adolescence versus adulthood: Differences in basal mesolimbic and nigrostriatal dopamine transmission and response to drugs of abuse. Addict Biol 2020; 25:e12721. [PMID: 30779271 DOI: 10.1111/adb.12721] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/06/2018] [Accepted: 01/08/2019] [Indexed: 12/21/2022]
Abstract
Epidemiological studies have shown that people who begin experimenting drugs of abuse during adolescence are more likely to develop substance use disorders, and the earliest is the beginning of their use, the greatest is the likelihood to become dependent. Understanding the neurobiological changes increasing adolescent vulnerability to drug use is becoming imperative. Although all neurotransmitter systems undergo relevant developmental changes, dopamine system is of particular interest, given its role in a variety of functions related to reward, motivation, and decision making. Thus, in the present study, we investigated differences in mesolimbic and nigrostriatal dopamine transmission between adolescent (5, 6, 7 weeks of age) and adult rats (10-12 weeks of age), in basal conditions and following drug challenge, by using in vivo brain microdialysis. Although no significant difference between adolescents and adults was observed in dopamine basal levels in the nucleus accumbens (NAc)shell and core, reduced DA levels were found in the dorsolateral striatum (DLS) of early and mid-adolescent rats. Adolescent rats showed greater increase of dopamine in the NAc shell following nicotine (0.4 mg/kg), THC (1.0 mg/kg), and morphine (1.0 mg/kg), in the NAc core following nicotine and morphine, and in the DLS following THC, morphine, and cocaine (10 mg/kg). These results, while adding new insight in the development and functionality of the dopamine system during different stages of adolescence, might provide a neurochemical basis for the greater vulnerability of adolescents to drugs of abuse and for the postulated gateway effect of nicotine and THC toward abuse of other illicit substances.
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Affiliation(s)
- Silvia Corongiu
- Department of Biomedical Sciences, Neuropsychopharmacology SectionUniversity of Cagliari Italy
| | - Christian Dessì
- National Research Council of ItalyInstitute of Neuroscience Italy
| | - Cristina Cadoni
- National Research Council of ItalyInstitute of Neuroscience Italy
- Centre of Excellence “Neurobiology of Dependence”University of Cagliari Italy
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Moazen P, Azizi H, Salmanzadeh H, Semnanian S. Adolescent morphine exposure induces immediate and long-term increases in impulsive behavior. Psychopharmacology (Berl) 2018; 235:3423-3434. [PMID: 30350222 DOI: 10.1007/s00213-018-5051-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 09/24/2018] [Indexed: 02/04/2023]
Abstract
RATIONALE Adolescence in humans represents a unique and critical developmental time point associated with increased risk-taking behavior. Converging clinical and epidemiological studies report a peak of drug use during adolescence, leading to the hypothesis that the developing adolescents brain is at risk to lose control over drug intake. Both adolescence and drug abuse are associated with significant cognitive and psychological changes such as lack of impulse control. A simple definition for impulsive behavior is the tendency to act prematurely without foresight. Increase in impulsivity is evident in acute morphine consumption, but to date, little is known with respect to subchronic morphine administration in impulsive behavior, particularly comparing time-dependent effects in adults, young adults, and adolescents. METHODS To evaluate this, adult, young adult, and adolescent rats were treated with a subchronic regimen of morphine or saline during 5 days (s.c.). Thereafter, we examined impulsive behavioral effects of morphine administration, 24 h and 25 days after administration in rats, while responding under a five-choice serial reaction time task (5-CSRTT). RESULTS Subchronic morphine administration increased premature responding 24 h after the last injection of morphine in adult, young adult, and adolescent rats without increasing motor activity but a significant change in motivation in adult and young adult rats only. After 25 days of abstinence, premature responses were significantly increased in comparison with baseline in adolescent rats but not in adults and young adults. CONCLUSION The main conclusion of this study is that morphine exposure in adolescents has a long-term profound effect on motor impulsive behavior later in adulthood. An implication of our findings might be that we should be especially careful about consuming and prescribing opioid drugs in adolescents.
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Affiliation(s)
- Parisa Moazen
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Hossein Azizi
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Hamed Salmanzadeh
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Saeed Semnanian
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
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Adolescent rats fail to demonstrate a LiCl-induced pre-exposure effect: Implications for the balance of drug reward and aversion in adolescence. Learn Behav 2018; 44:356-365. [PMID: 27129788 DOI: 10.3758/s13420-016-0227-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Adolescents display weaker taste avoidance induced by both abused and non-abused drugs than adults. Drug history attenuates avoidance learning in adults (the drug pre-exposure effect), but little is known about this phenomenon in adolescents. Given that the weaker taste avoidance in adolescence is thought to be a function of their relative insensitivity to the drug's aversive effects, it might be expected that the drug pre-exposure effect would be weaker in adolescents given that for some drugs this effect is mediated by associative blocking that depends on the association of environmental cues with the drug's aversive effects. To address this, in the present studies male adolescent (Experiment 1) and adult (Experiment 2) rats were given five spaced injections of LiCl prior to subsequent taste avoidance conditioning with LiCl. Consistent with past reports, adolescents displayed weaker taste avoidance than adults. While adults displayed attenuated LiCl-induced taste avoidance following LiCl pre-exposure, adolescents showed no evidence of this pre-exposure. This work is consistent with the view that adolescents are relatively insensitive to the aversive effects of drugs, an insensitivity potentially important in subsequent intake of drugs of abuse given that such intake is a function of the balance of their rewarding and aversive effects.
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Chambers KC. Conditioned taste aversions. World J Otorhinolaryngol Head Neck Surg 2018; 4:92-100. [PMID: 30035267 PMCID: PMC6051479 DOI: 10.1016/j.wjorl.2018.02.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 02/26/2018] [Indexed: 11/21/2022] Open
Abstract
When one becomes ill after consuming a meal, there is a propensity to target a particular taste as the cause of the illness. The qualities of the taste most likely targeted include more novel, less preferred, and higher protein content. This association between a particular taste and illness is a form of learning that is termed conditioned taste aversion (CTA). A consequence of the learned association is that the taste will become aversive. When experiencing the taste again, individuals will show aversive reactions such as expressions of loathing, will experience mimicked illness sensations such as nausea, and subsequently, will avoid further exposure to the taste. The ability to acquire CTA occurs across species and across ages within a species. In the rat animal model, however, age differences exist in the capability of acquiring CTAs when increasingly longer intervals are imposed between consumption of a novel sweet solution and onset of illness. Pups have a decreased ability compared to young adults while aged rats have an increased ability. Evidence suggests that the failure of pups to acquire CTA at longer intervals is due to an immature retrieval mechanism and the facilitated ability of aged rats is due to a compromised clock mechanism that tracks the passage of time. Learned taste-illness association serves the critical function of informing individuals of the toxic nature of certain foods, thus preventing further illness and potentially death. Additionally, it contributes to the hypophagia observed during cancer chemotherapy and may contribute to the hypophagia found while suffering from bacterial infection, chronic medical conditions such as cancer, and restrictive food intake disorders such as anorexia nervosa.
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The GHR-R antagonist JMV 2959 neither induces malaise nor alters the malaise property of LiCl in the adult male rat. Physiol Behav 2017; 183:46-48. [PMID: 29056353 DOI: 10.1016/j.physbeh.2017.10.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 10/16/2017] [Accepted: 10/16/2017] [Indexed: 10/18/2022]
Abstract
The orexigenic peptide ghrelin (GHR) interacts with ghrelin receptors (GHR-Rs) to modulate brain reinforcement and feeding circuits. Pharmacological inactivation of GHR-Rs via administration of the drug JMV 2959 attenuates the rewarding/reinforcing effects of several drugs of abuse including alcohol, morphine, amphetamine and nicotine. One view of these results is that inactivation of GHR-Rs taps into brain reinforcement/feeding circuits acted upon by drugs of abuse. An alternate explanation is that JMV 2959 may induce malaise, which in turn may limit reinforcement as well as food ingestion. This is a variable of interest given that nicotine alone can induce malaise which may be enhanced by JMV 2959. In the present study, we assessed the capacity of JMV 2959 to produce malaise using a conditioned taste aversion (CTA) task. Adult male rats were allowed to consume a 0.1% sodium saccharin solution and then injected IP with either vehicle, 0.4mg/kg nicotine, 3mg/kg JMV 2959, a combination of 0.4mg/kg nicotine and 3mg/kg JMV 2959, or 32mg/kg lithium chloride (a positive control known to support induction of CTA). Lithium chloride produced a robust avoidance of the saccharin solution in subsequent 2 bottle (water and saccharin) tests, whereas JMV 2959 alone did not induce CTA. The combination of JMV 2959 and nicotine induced a moderate degree of CTA that was similar to that produced by nicotine alone. These results suggest that JMV 2959 is unlikely to limit either reinforcement or food ingestion via induction of malaise.
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10
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Meyer HC, Bucci DJ. Age differences in appetitive Pavlovian conditioning and extinction in rats. Physiol Behav 2016; 167:354-362. [PMID: 27737779 PMCID: PMC5159263 DOI: 10.1016/j.physbeh.2016.10.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/07/2016] [Accepted: 10/07/2016] [Indexed: 01/10/2023]
Abstract
Mounting evidence indicates that adolescents exhibit heightened sensitivity to rewards and reward-related cues compared to adults, and that adolescents are often unable to exert behavioral control in the face of such cues. Moreover, differences in reward processing during adolescence have been linked to heightened risk taking and impulsivity. However, little is known about the processes by which adolescents learn about the appetitive properties of environmental stimuli that signal reward. To address this, Pavlovian conditioning procedures were used to test for differences in excitatory conditioning between adult and adolescent rats using various schedules of reinforcement. Specifically, separate cohorts of adult and adolescent rats were trained under conditions of consistent (continuous) or intermittent (partial) reinforcement. We found that the acquisition of anticipatory responding to a continuously-reinforced cue proceeded similarly in adolescents and adults. In contrast, responding increased at a greater rate in adolescents compared to adults during presentations of a partially-reinforced cue. We subsequently compared the ability of adolescent and adult rats to dynamically adjust the representation of a reward-predictive cue during extinction trials, in which a secondary inhibitory representation is acquired for the previously-reinforced stimulus. We observed significant age differences in the ability to flexibly update cue representations during extinction, in that the appetitive properties of cues with a history of either continuous or partial reinforcement persisted to a greater extent in adolescents relative to adults.
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Affiliation(s)
- Heidi C Meyer
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755, United States.
| | - David J Bucci
- Department of Psychological and Brain Sciences, Dartmouth College, Hanover, NH 03755, United States
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11
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Doremus-Fitzwater TL, Spear LP. Reward-centricity and attenuated aversions: An adolescent phenotype emerging from studies in laboratory animals. Neurosci Biobehav Rev 2016; 70:121-134. [PMID: 27524639 PMCID: PMC5612441 DOI: 10.1016/j.neubiorev.2016.08.015] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 08/10/2016] [Accepted: 08/10/2016] [Indexed: 12/21/2022]
Abstract
Adolescence is an evolutionarily conserved developmental period, with neural circuits and behaviors contributing to the detection, procurement, and receipt of rewards bearing similarity across species. Studies with laboratory animals suggest that adolescence is typified by a "reward-centric" phenotype-an increased sensitivity to rewards relative to adults. In contrast, adolescent rodents are reportedly less sensitive to the aversive properties of many drugs and naturally aversive stimuli. Alterations within the mesocorticolimbic dopamine and endocannabinoid systems likely contribute to an adolescent reward-sensitive, yet aversion-resistant, phenotype. Although early hypotheses postulated that developmental changes in dopaminergic circuitry would result in a "reward deficiency" syndrome, evidence now suggests the opposite: that adolescents are uniquely poised to seek out hedonic stimuli, experience greater "pleasure" from rewards, and consume rewarding stimuli in excess. Future studies that more clearly define the role of specific brain regions and neurotransmitter systems in the expression of behaviors toward reward- and aversive-related cues and stimuli are necessary to more fully understand an adolescent-proclivity for and vulnerability to rewards and drugs of potential abuse.
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Affiliation(s)
- Tamara L Doremus-Fitzwater
- Developmental Alcohol Exposure Research Center, Center for Development and Behavioral Neuroscience, Department of Psychology, Binghamton University, Binghamton, New York 13902-6000, USA.
| | - Linda P Spear
- Developmental Alcohol Exposure Research Center, Center for Development and Behavioral Neuroscience, Department of Psychology, Binghamton University, Binghamton, New York 13902-6000, USA
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12
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Camarini R, Pautassi RM. Behavioral sensitization to ethanol: Neural basis and factors that influence its acquisition and expression. Brain Res Bull 2016; 125:53-78. [PMID: 27093941 DOI: 10.1016/j.brainresbull.2016.04.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 04/07/2016] [Accepted: 04/08/2016] [Indexed: 12/29/2022]
Abstract
Ethanol-induced behavioral sensitization (EBS) was first described in 1980, approximately 10 years after the phenomenon was described for psychostimulants. Ethanol acts on γ-aminobutyric acid (GABA) and glutamate receptors as an allosteric agonist and antagonist, respectively, but it also affects many other molecular targets. The multiplicity of factors involved in the behavioral and neurochemical effects of ethanol and the ensuing complexity may explain much of the apparent disparate results, found across different labs, regarding ethanol-induced behavioral sensitization. Although the mesocorticolimbic dopamine system plays an important role in EBS, we provide evidence of the involvement of other neurotransmitter systems, mainly the glutamatergic, GABAergic, and opioidergic systems. This review also analyses the neural underpinnings (e.g., induction of cellular transcription factors such as cyclic adenosine monophosphate response element binding protein and growth factors, such as the brain-derived neurotrophic factor) and other factors that influence the phenomenon, including age, sex, dose, and protocols of drug administration. One of the reasons that make EBS an attractive phenomenon is the assumption, firmly based on empirical evidence, that EBS and addiction-related processes have common molecular and neural basis. Therefore, EBS has been used as a model of addiction processes. We discuss the association between different measures of ethanol-induced reward and EBS. Parallels between the pharmacological basis of EBS and acute motor effects of ethanol are also discussed.
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Affiliation(s)
- Rosana Camarini
- Departamento de Farmacologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, SP, Brazil.
| | - Ricardo Marcos Pautassi
- Instituto de Investigaciones Médicas M. y M. Ferreyra, Córdoba (IMMF-CONICET-Universidad Nacional de Córdoba), Universidad Nacional de Córdoba, Argentina
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13
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Cocaine self-administration punished by intravenous histamine in adolescent and adult rats. Behav Pharmacol 2016; 26:393-7. [PMID: 25769092 DOI: 10.1097/fbp.0000000000000136] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Adolescence is a transitional phase marked by a heightened vulnerability to substances of abuse. It has been hypothesized that both increased sensitivity to reward and decreased sensitivity to aversive events may drive drug-use liability during this phase. To investigate possible age-related differences in sensitivity to the aversive consequences of drug use, adolescent and adult rats were compared on self-administration of cocaine before, during, and after a 10-day period in which an aversive agent, histamine, was added to the cocaine solution. Adult and adolescent female rats were trained to self-administer intravenous cocaine (0.4 mg/kg/infusion) over 10 sessions (2 h/session; 2 sessions/day). Histamine (4 mg/kg/infusion) was then added directly into the cocaine solution for the next 10 sessions. Finally, the cocaine/histamine solution was replaced with a cocaine-only solution, and rats continued to self-administer cocaine (0.4 mg/kg) for 20 sessions. Compared with adolescent rats, adult rats showed a greater decrease in cocaine self-administration when it was punished with intravenous histamine compared with their baseline cocaine self-administration rates. These results suggest that differences in the sensitivity to negative consequences of drug use may partially explain developmental differences in drug use vulnerability.
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Saalfield J, Spear L. The ontogeny of ethanol aversion. Physiol Behav 2016; 156:164-70. [PMID: 26774181 DOI: 10.1016/j.physbeh.2016.01.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 01/11/2016] [Accepted: 01/12/2016] [Indexed: 01/29/2023]
Abstract
Recent work has suggested separate developmental periods within the broader framework of adolescence, with data suggesting distinct alterations and vulnerabilities within these intervals. While previous research has suggested reduced sensitivity to the aversive effects of alcohol in adolescence relative to adults, a more detailed ontogeny of this effect has yet to be conducted. The adolescent brain undergoes significant transitions throughout adolescence, including in regions linked with drug reward and aversion. The current study aimed to determine the ontogeny of ethanol aversion by utilizing a conditioned taste aversion procedure at six different ages to test the hypothesis that the transitions into, through, and out of adolescence are associated with ontogenetic alterations in sensitivity to the aversive properties of ethanol. Non-deprived animals given Boost® as the conditioned stimulus (CS) were used in Experiment 1, whereas Experiment 2 used water-restricted animals provided with a saccharin/sucrose solution as the CS. In both experiments, an attenuated sensitivity to the aversive properties of ethanol was evident in adolescents compared to adults, although more age differences were apparent in water deprived animals than when a highly palatable CS was given to ad libitum animals. Overall, the data suggest an attenuated sensitivity to the aversive properties of ethanol that is most pronounced during pre- and early adolescence, declining thereafter to reach the enhanced aversive sensitivity of adults.
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Affiliation(s)
- Jessica Saalfield
- Binghamton University, PO Box 6000, Binghamton, NY 13902, United States.
| | - Linda Spear
- Binghamton University, PO Box 6000, Binghamton, NY 13902, United States
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15
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Kuhn C. Emergence of sex differences in the development of substance use and abuse during adolescence. Pharmacol Ther 2015; 153:55-78. [PMID: 26049025 DOI: 10.1016/j.pharmthera.2015.06.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 04/29/2015] [Indexed: 12/24/2022]
Abstract
Substance use and abuse begin during adolescence. Male and female adolescent humans initiate use at comparable rates, but males increase use faster. In adulthood, more men than women use and abuse addictive drugs. However, some women progress more rapidly from initiation of use to entry into treatment. In animal models, adolescent males and females consume addictive drugs similarly. However, reproductively mature females acquire self-administration faster, and in some models, escalate use more. Sex/gender differences exist in neurobiologic factors mediating both reinforcement (dopamine, opioids) and aversiveness (CRF, dynorphin), as well as intrinsic factors (personality, psychiatric co-morbidities) and extrinsic factors (history of abuse, environment especially peers and family) which influence the progression from initial use to abuse. Many of these important differences emerge during adolescence, and are moderated by sexual differentiation of the brain. Estradiol effects which enhance both dopaminergic and CRF-mediated processes contribute to the female vulnerability to substance use and abuse. Testosterone enhances impulsivity and sensation seeking in both males and females. Several protective factors in females also influence initiation and progression of substance use including hormonal changes of pregnancy as well as greater capacity for self-regulation and lower peak levels of impulsivity/sensation seeking. Same sex peers represent a risk factor more for males than females during adolescence, while romantic partners increase risk for women during this developmental epoch. In summary, biologic factors, psychiatric co-morbidities as well as personality and environment present sex/gender-specific risks as adolescents begin to initiate substance use.
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Affiliation(s)
- Cynthia Kuhn
- Department of Pharmacology and Cancer Biology, Box 3813, Duke University Medical Center, Durham, NC 27710, United States.
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Saalfield J, Spear L. Consequences of repeated ethanol exposure during early or late adolescence on conditioned taste aversions in rats. Dev Cogn Neurosci 2015; 16:174-182. [PMID: 25698309 PMCID: PMC4512940 DOI: 10.1016/j.dcn.2015.01.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 01/05/2015] [Accepted: 01/17/2015] [Indexed: 12/24/2022] Open
Abstract
Adolescent Intermittent Ethanol (AIE) resulted in attenuated CTA in adulthood. AIE in late adolescence resulted in greater CTA attenuation 2 days post-exposure. All AIE animals were equally insensitive when tested 3 weeks post-exposure. No metabolic tolerance was noted following AIE. AIE results in a decreased sensitivity to aversive effects of ethanol in adulthood.
Alcohol use is prevalent during adolescence, yet little is known about possible long-lasting consequences. Recent evidence suggests that adolescents are less sensitive than adults to ethanol's aversive effects, an insensitivity that may be retained into adulthood after repeated adolescent ethanol exposure. This study assessed whether intermittent ethanol exposure during early or late adolescence (early-AIE or late-AIE, respectively) would affect ethanol conditioned taste aversions 2 days (CTA1) and >3 weeks (CTA2) post-exposure using supersaccharin and saline as conditioning stimuli (CS), respectively. Pair-housed male Sprague-Dawley rats received 4 g/kg i.g. ethanol (25%) or water every 48 h from postnatal day (P) 25–45 (early AIE) or P45-65 (late AIE), or were left non-manipulated (NM). During conditioning, 30 min home cage access to the CS was followed by 0, 1, 1.5, 2 or 2.5 g/kg ethanol i.p., with testing 2 days later. Attenuated CTA relative to controls was seen among early and late AIE animals at both CTA1 and CTA2, an effect particularly pronounced at CTA1 after late AIE. Thus, adolescent exposure to ethanol was found to induce an insensitivity to ethanol CTA seen soon after exposure and lasting into adulthood, and evident with ethanol exposures not only early but also later in adolescence.
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Affiliation(s)
- Jessica Saalfield
- Binghamton University, Psychology Department, P.O. Box 6000, Binghamton, NY 13902, United States.
| | - Linda Spear
- Binghamton University, Psychology Department, P.O. Box 6000, Binghamton, NY 13902, United States
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Lydon DM, Wilson SJ, Child A, Geier CF. Adolescent brain maturation and smoking: what we know and where we're headed. Neurosci Biobehav Rev 2014; 45:323-42. [PMID: 25025658 PMCID: PMC4451244 DOI: 10.1016/j.neubiorev.2014.07.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 05/30/2014] [Accepted: 07/03/2014] [Indexed: 11/22/2022]
Abstract
Smoking is a leading cause of mortality and morbidity worldwide. Smoking initiation often occurs during adolescence. This paper reviews and synthesizes adolescent development and nicotine dependence literatures to provide an account of adolescent smoking from onset to compulsive use. We extend neurobiological models of adolescent risk-taking, that focus on the interplay between incentive processing and cognitive control brain systems, through incorporating psychosocial and contextual factors specific to smoking, to suggest that adolescents are more vulnerable than adults to cigarette use generally, but that individual differences exist placing some adolescents at increased risk for smoking. Upon smoking, adolescents are more likely to continue smoking due to the increased positive effects induced by nicotine during this period. Continued use during adolescence, may be best understood as reflecting drug-related changes to neural systems underlying incentive processing and cognitive control, resulting in decision-making that is biased towards continued smoking. Persistent changes following nicotine exposure that may underlie continued dependence are described. We highlight ways that interventions may benefit from a consideration of cognitive-neuroscience findings.
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Affiliation(s)
- David M Lydon
- Department of Human Development and Family Studies, College of Health and Human Development, The Pennsylvania State University, 315 Health and Human Development - East, University Park, PA 16802, United States.
| | - Stephen J Wilson
- Department of Psychology, The College of the Liberal Arts, The Pennsylvania State University, 311 Moore Building, University Park, PA 16802, United States
| | - Amanda Child
- Department of Human Development and Family Studies, College of Health and Human Development, The Pennsylvania State University, 315 Health and Human Development - East, University Park, PA 16802, United States
| | - Charles F Geier
- Department of Human Development and Family Studies, College of Health and Human Development, The Pennsylvania State University, 315 Health and Human Development - East, University Park, PA 16802, United States
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Viral over-expression of D1 dopamine receptors in the prefrontal cortex increase high-risk behaviors in adults: comparison with adolescents. Psychopharmacology (Berl) 2014; 231:1615-26. [PMID: 24408208 PMCID: PMC3969417 DOI: 10.1007/s00213-013-3399-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 12/06/2013] [Indexed: 02/06/2023]
Abstract
RATIONALE Adolescents are often described as "lacking brakes" resulting in an increase in several behaviors associated with risk for addiction. Prefrontal cortex dopamine and cortico-limbic interaction play an important role in addiction, and we have previously shown that the dopamine D1 receptor is elevated on prelimbic prefrontal output neurons in adolescent rats. We hypothesized that a constellation of risk-related behaviors is mediated by prefrontal output neuron expression of D1. OBJECTIVES We aimed to determine the role of the dopamine D1 receptor in behavioral and neural correlates of risk for addiction that are often observed in adolescents. Therefore, high-risk behaviors as well as subcortical D2 receptor expression were investigated in adult animals with experimentally elevated D1 on prefrontal glutamatergic neurons. METHODS A lentiviral vector that selectively expressed the D1 receptor within glutamate neurons was injected in the prelimbic prefrontal cortex of adult male rats. Place conditioning to cocaine, alcohol, and nicotine, as well as delay discounting, novelty preferences, anxiety, cocaine self-administration, and sucrose preferences were assessed. RESULTS Virally mediated D1 over-expression in adults leads to stronger drug-cue associations and greater consumption of sweet solutions, elevates bias towards immediate satisfaction rather than delaying gratification, decreases anxiety, and causes rats to work harder for and take more cocaine. Furthermore, elevated cortical D1 reduces D2 receptors in the accumbens (a putative risk marker). CONCLUSIONS Together, these data suggest a common mechanism for increased motivational drive to seek and consume substances with hedonic value, consistent with adolescent addictive processes.
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Effect of sex on ethanol consumption and conditioned taste aversion in adolescent and adult rats. Psychopharmacology (Berl) 2014; 231:1831-9. [PMID: 24158502 PMCID: PMC4058910 DOI: 10.1007/s00213-013-3319-y] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 10/05/2013] [Indexed: 12/14/2022]
Abstract
RATIONALE Vulnerability to alcoholism is determined by many factors, including the balance of pleasurable vs. aversive alcohol-induced sensations: pleasurable sensations increase intake, while aversive sensations decrease it. Female sex and adolescent age are associated with lower sensitivity to intake-reducing effects and more rapid development of alcohol abuse. OBJECTIVES This study assessed voluntary drinking and the aversive effects of alcohol to determine whether these measures are inversely related across the sexes and development. METHODS Voluntary drinking of 20 % ethanol in an every-other-day (EOD) availability pattern and the dose-response relationship of ethanol conditioned taste aversion (CTA) were assessed in male and female adolescent and adult rats. RESULTS CTA was sex specific in adult but not adolescent rats, with adult females exhibiting less aversion. Voluntary ethanol consumption varied according to age and individual differences but was not sex specific. Adolescents initially drank more than adults, exhibited greater day-to-day variation in consumption, were more susceptible to the alcohol deprivation effect, and took longer to establish individual differences in consumption patterns. CONCLUSIONS These results show that the emergence of intake patterns differs between adolescents and adults. Adolescents as a group initiate drinking at high levels but decrease intake as they mature. A subset of adolescents maintained high drinking levels into adulthood. In contrast, most adults consumed at steady, low levels, but a small subset quickly established and maintained high-consumption patterns. Adolescents also showed marked deprivation-induced increases. Sex differences were not observed in EOD drinking during either adolescence or adulthood.
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Wetzell BB, Muller MM, Cobuzzi JL, Hurwitz ZE, DeCicco-Skinner K, Riley AL. Effect of age on methylphenidate-induced conditioned taste avoidance and related BDNF/TrkB signaling in the insular cortex of the rat. Psychopharmacology (Berl) 2014; 231:1493-501. [PMID: 24563186 DOI: 10.1007/s00213-014-3500-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 02/07/2014] [Indexed: 12/29/2022]
Abstract
RATIONALE Drug use and abuse is thought to be a function of the balance between its rewarding and aversive effects, such that the rewarding effects increase the likelihood of use while the drug's dissociable aversive effects limit it. Adolescents exhibit a shift in this balance toward reward, which may ultimately lead to increased use. Importantly, recent work shows that adolescents are also protected from the aversive effects of many abusable drugs as measured by conditioned taste avoidance (CTA). However, such effects of methylphenidate (MPH, widely prescribed to adolescents with ADHD) have not been characterized. OBJECTIVES The effect of age on MPH-induced CTA was assessed. In addition, MPH-induced changes in brain-derived neurotrophic factor (BDNF) activity in the insular cortex (IC) and central nucleus of the amygdala (CeA), known to be important to CTA, were examined and related to CTAs in adolescents and adults. METHODS CTAs induced by MPH (0, 10, 18, and 32 mg/kg) were assessed in adolescent (n = 34) and adult (n = 33) male Sprague Dawley rats. Following MPH CTA, IC and CeA tissue was probed for differences in BDNF and tropomyosin-related kinase receptor-B (TrkB) using Western blots. RESULTS Blunted expression of MPH CTA was observed in the adolescents versus adults, which correlated with generally attenuated adolescent BDNF/TrkB activity in the IC, but the drug effects ran contrary to the expression of CTA. CONCLUSIONS Adolescents are protected from the aversive effects of MPH versus adults, but further work is needed to characterize the possible involvement of BDNF/TrkB.
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Affiliation(s)
- B Bradley Wetzell
- Psychopharmacology Laboratory, Department of Psychology, American University, 4400 Massachusetts Avenue NW, Washington, DC, 20016, USA,
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21
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Effects of repeated exposure to morphine in adolescent and adult male C57BL/6J mice: age-dependent differences in locomotor stimulation, sensitization, and body weight loss. Psychopharmacology (Berl) 2014; 231:1517-29. [PMID: 24096538 PMCID: PMC3969384 DOI: 10.1007/s00213-013-3298-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/11/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Given evidence for age-related differences in the effects of drugs of abuse, surprisingly few preclinical studies have explored effects of opioids in adolescents (versus adults). OBJECTIVES This study compared the motor stimulating and ataxic effects of repeatedly administered morphine in adolescent, late adolescent, and adult mice. METHODS Mice were treated with saline or morphine (10-100 mg/kg, i.p.) once per day for 4 days, and morphine (3.2-56 mg/kg)-induced locomotion was assessed 3 days or 5 weeks later. Different mice were treated repeatedly with morphine and ataxia was measured. RESULTS Acute administration of morphine increased locomotion more in adolescents than in adults. Repeated morphine enhanced morphine-induced locomotion, assessed 3 days later, to a similar extent in each age group (minimum effective dose 17.8 mg/kg). This sensitization was still evident 5 weeks later when the adolescents had become adult, but was smaller and occurred at a higher dose (56 mg/kg). In animals treated repeatedly with morphine as adults, sensitization was no longer apparent 5 weeks later. Intermittent morphine was at least 10-fold less potent to produce body weight loss in adolescents than in adults. Repeated morphine did not alter morphine-induced ataxia at any age. CONCLUSIONS Compared with adults, adolescents were more sensitive to the acute locomotor stimulating effects of morphine and to its long-lasting locomotor sensitizing effects, consistent with overactivity of dopamine systems during adolescence. In contrast, adolescents were less sensitive than adults to body weight loss induced by intermittent morphine, an effect indicative of morphine withdrawal in adult rodents.
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Anderson RI, Morales M, Spear LP, Varlinskaya EI. Pharmacological activation of kappa opioid receptors: aversive effects in adolescent and adult male rats. Psychopharmacology (Berl) 2014; 231:1687-93. [PMID: 23604334 PMCID: PMC3760984 DOI: 10.1007/s00213-013-3095-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 03/28/2013] [Indexed: 12/20/2022]
Abstract
RATIONALE The dynorphin (DYN)/kappa opioid receptor (KOR) system is involved in the dysphoric properties of drugs of abuse. Given that adolescents show reduced sensitivity to aversive effects of many drugs, alterations in the DYN/KOR system may contribute to the prevalence of drug use during adolescence. OBJECTIVES The present study was designed to assess dysphoric properties of a selective kappa agonist, U62,066, in adolescent and adult rats using both conditioned taste aversion (CTA) and conditioned place aversion (CPA) paradigms. METHODS For CTA, water-restricted rats were administered U62,066 following 30 min access to a saccharin solution, with subsequent saccharin consumption used to index aversion. For CPA, animals were allowed access to both compartments of a two-compartment chamber for a 15-min pre- and post-conditioning test. For conditioning, subjects were administered U62,066 prior to confinement to one side of the chamber and saline prior to confinement to the other side for a total of four pairings. RESULTS Overall, adolescents displayed reduced sensitivity to the kappa agonist relative to adults. Adults demonstrated taste aversions to the 0.2 and 0.3 mg/kg doses of U62,066, whereas adolescents did not display aversions to any tested doses. Adults demonstrated a place aversion to the 0.1 and 0.2 mg/kg dose of U62,066 when paired with the preferred side of the conditioning chamber. Adolescents did not display aversions to any of the doses tested. CONCLUSIONS Reduced sensitivity to DYN/KOR system activation during adolescence may be a contributing factor to the age-typical insensitivity to aversive properties of drugs commonly abused by adolescents.
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Affiliation(s)
- Rachel I Anderson
- Center for Development and Behavioral Neuroscience, Department of Psychology, Binghamton University, 4400 Vestal Parkway East, Binghamton, NY, 13902-6000, USA,
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Bernheim A, Halfon O, Boutrel B. Controversies about the enhanced vulnerability of the adolescent brain to develop addiction. Front Pharmacol 2013; 4:118. [PMID: 24348419 PMCID: PMC3842532 DOI: 10.3389/fphar.2013.00118] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Accepted: 08/29/2013] [Indexed: 12/14/2022] Open
Abstract
Adolescence, defined as a transition phase toward autonomy and independence, is a natural time of learning and adjustment, particularly in the setting of long-term goals and personal aspirations. It also is a period of heightened sensation seeking, including risk taking and reckless behaviors, which is a major cause of morbidity and mortality among teenagers. Recent observations suggest that a relative immaturity in frontal cortical neural systems may underlie the adolescent propensity for uninhibited risk taking and hazardous behaviors. However, converging preclinical and clinical studies do not support a simple model of frontal cortical immaturity, and there is substantial evidence that adolescents engage in dangerous activities, including drug abuse, despite knowing and understanding the risks involved. Therefore, a current consensus considers that much brain development during adolescence occurs in brain regions and systems that are critically involved in the perception and evaluation of risk and reward, leading to important changes in social and affective processing. Hence, rather than naive, immature and vulnerable, the adolescent brain, particularly the prefrontal cortex, should be considered as prewired for expecting novel experiences. In this perspective, thrill seeking may not represent a danger but rather a window of opportunities permitting the development of cognitive control through multiple experiences. However, if the maturation of brain systems implicated in self-regulation is contextually dependent, it is important to understand which experiences matter most. In particular, it is essential to unveil the underpinning mechanisms by which recurrent adverse episodes of stress or unrestricted access to drugs can shape the adolescent brain and potentially trigger life-long maladaptive responses.
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Affiliation(s)
- Aurélien Bernheim
- Center for Psychiatric Neuroscience, Division of Child and Adolescent Psychiatry, Lausanne University Hospital Lausanne, Switzerland
| | - Olivier Halfon
- Division of Child and Adolescent Psychiatry, Lausanne University Hospital Lausanne, Switzerland
| | - Benjamin Boutrel
- Center for Psychiatric Neuroscience, Division of Child and Adolescent Psychiatry, Lausanne University Hospital Lausanne, Switzerland ; Division of Child and Adolescent Psychiatry, Lausanne University Hospital Lausanne, Switzerland
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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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25
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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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26
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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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27
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Arrant AE, Coburn E, Jacobsen J, Kuhn CM. Lower anxiogenic effects of serotonin agonists are associated with lower activation of amygdala and lateral orbital cortex in adolescent male rats. Neuropharmacology 2013; 73:359-67. [PMID: 23774134 DOI: 10.1016/j.neuropharm.2013.05.030] [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: 02/05/2013] [Revised: 04/22/2013] [Accepted: 05/14/2013] [Indexed: 01/30/2023]
Abstract
There has been controversy over use of selective serotonin reuptake inhibitors (SSRIs) to treat affective disorders in children and adolescents due to clinical reports of increased risk for suicidal ideation and behavior during treatment, and animal studies showing changes in adult anxiety- and depressive-like behaviors after repeated treatment during adolescence. However, the acute effect of serotonergic drugs on affective behavior during adolescence is poorly understood. We investigated serotonergic modulation of anxiety-like behavior in adolescent (PN28-32) and adult (PN67-73) male rats using the SSRI fluoxetine, the 5-HT(1A) agonist 8-OH DPAT, and the 5-HT₂ agonist mCPP. Acute treatment with fluoxetine (10 mg/kg, i.p.) produced greater anxiogenic effects in adults than adolescents in the light/dark (LD) test for anxiety-like behavior, but fluoxetine (2.5, 5, and 10 mg/kg, i.p.) increased extracellular serotonin in the medial prefrontal cortex similarly in both ages. Adults were also more sensitive to the anxiogenic effects of 8-OH DPAT (0.25 and 0.5 mg/kg, i.p.), but not mCPP (0.5 and 1 mg/kg, i.p.), in the LD test. Fluoxetine (10 mg/kg) stimulated greater increases in c-Fos expression across the extended amygdala in adults than in adolescents, and 8-OH DPAT (0.5 mg/kg) produced greater increases in c-Fos in the lateral orbital cortex and central nucleus of the amygdala in adults. These data show that lower anxiogenic effects of acute SSRIs in adolescents are associated with lesser activation of cortical and amygdala brain regions. This immaturity could contribute to the different profile of behavioral effects observed in adolescents and adults treated with SSRIs.
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Affiliation(s)
- Andrew E Arrant
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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28
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Arrant AE, Schramm-Sapyta NL, Kuhn CM. Use of the light/dark test for anxiety in adult and adolescent male rats. Behav Brain Res 2013; 256:119-27. [PMID: 23721963 DOI: 10.1016/j.bbr.2013.05.035] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 04/20/2013] [Accepted: 05/20/2013] [Indexed: 12/19/2022]
Abstract
The light/dark (LD) test is a commonly used rodent test of unconditioned anxiety-like behavior that is based on an approach/avoidance conflict between the drive to explore novel areas and an aversion to brightly lit, open spaces. We used the LD test to investigate developmental differences in behavior between adolescent (postnatal day (PN) 28-34) and adult (PN67-74) male rats. We investigated whether LD behavioral measures reflect anxiety-like behavior similarly in each age group using factor analysis and multiple regression. These analyses showed that time in the light compartment, percent distance in the light, rearing, and latency to emerge into the light compartment were measures of anxiety-like behavior in each age group, while total distance traveled and distance in the dark compartment provided indices of locomotor activity. We then used these measures to assess developmental differences in baseline LD behavior and the response to anxiogenic drugs. Adolescent rats emerged into the light compartment more quickly than adults and made fewer pokes into the light compartment. These age differences could reflect greater risk taking and less risk assessment in adolescent rats than adults. Adolescent rats were less sensitive than adults to the anxiogenic effects of the benzodiazepine inverse agonist N-methyl-β-carboline-3-carboxamide (FG-7142) and the α₂ adrenergic antagonist yohimbine on anxiety-like behaviors validated by factor analysis, but locomotor variables were similarly affected. These data support the results of the factor analysis and indicate that GABAergic and noradrenergic modulation of LD anxiety-like behavior may be immature during adolescence.
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Affiliation(s)
- Andrew E Arrant
- Department of Pharmacology & Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA
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29
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Radke AK, Holtz NA, Gewirtz JC, Carroll ME. Reduced emotional signs of opiate withdrawal in rats selectively bred for low (LoS) versus high (HiS) saccharin intake. Psychopharmacology (Berl) 2013; 227:117-26. [PMID: 23254375 PMCID: PMC3624049 DOI: 10.1007/s00213-012-2945-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 12/01/2012] [Indexed: 02/01/2023]
Abstract
RATIONALE Rats bred for high (HiS) and low (LoS) saccharin intake exhibit divergent behavioral responses to multiple drugs of abuse, with HiS rats displaying greater vulnerability to drug taking. Previous research indicates that this effect may be due to increased sensitivity to reward in HiS rats and to the aversive effects of acute drug administration in LoS rats. OBJECTIVE The current study investigated whether HiS and LoS rats also exhibit different behavioral signs of withdrawal following one or repeated opiate exposures. METHODS Emotional signs of opiate withdrawal were assessed with potentiation of the acoustic startle reflex and conditioned place aversion (CPA) in male and female HiS and LoS rats. Startle was measured before and 4 h after a 10-mg/kg injection of morphine on days 1, 2, and 7 of opiate exposure. CPA was induced with a 2-day, naloxone-precipitated conditioning paradigm. Somatic signs of withdrawal and weight loss were also measured. RESULTS Male and female LoS rats exhibited lower startle potentiation than HiS rats on the seventh day of morphine exposure. LoS male rats also failed to develop a CPA to morphine withdrawal. No differences in physical withdrawal signs were observed between HiS and LoS rats, but males of both lines had more physical signs of withdrawal than females. CONCLUSIONS These results suggest that LoS rats are less vulnerable to the negative emotional effects of morphine withdrawal than HiS rats. A less severe withdrawal syndrome may contribute to decreased levels of drug taking in the LoS line.
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Affiliation(s)
- Anna K. Radke
- Department of Psychiatry, University of Minnesota, Minneapolis, MN 55455, USA
,National Institute of Alcohol Abuse and Alcoholism National Institutes of Health 5625 Fishers Lane Rockville, MD 20852 Phone: 301-443-4052 Fax: 301-480-1952
| | - Nathan A. Holtz
- Department of Psychiatry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jonathan C. Gewirtz
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
,Department of Psychology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Marilyn E. Carroll
- Department of Psychiatry, University of Minnesota, Minneapolis, MN 55455, USA
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Drescher C, Foscue EP, Kuhn CM, Schramm-Sapyta NL. Individual differences in cocaine conditioned taste aversion are developmentally stable and independent of locomotor effects of cocaine. Dev Cogn Neurosci 2013; 1:600-5. [PMID: 21927632 DOI: 10.1016/j.dcn.2011.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Drugs of abuse induce complex motivational states in their users which have been shown to vary developmentally. In addition to developmental variation, interindividual variation in the rewarding and aversive effects of drugs of abuse is an important consideration. A rat model was used to assess whether the conditioned rewarding/aversive effects of cocaine were maintained as individuals matured from adolescence into adulthood. We tested rats in the cocaine conditioned taste aversion task as adolescents and again in adulthood. We observed a wide range of approach/avoidance behaviors in this task, and also observed that the relative interindividual differences in approach/avoidance are remarkably stable across the two developmental stages. Furthermore, we observed that these interindividual differences are not attributable to individual differences in cocaine-induced locomotor effects or individual differences in blood or brain cocaine levels. Taken together, these findings indicate that sensitivity to cocaine’s motivational effects is stable across development and part of a unique neurological process.
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Affiliation(s)
- Caitlin Drescher
- Department of Psychiatry, Duke University Medical Center, Durham, NC 27710, United States
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Rewards, aversions and affect in adolescence: emerging convergences across laboratory animal and human data. Dev Cogn Neurosci 2013; 1:392-400. [PMID: 21918675 DOI: 10.1016/j.dcn.2011.08.001] [Citation(s) in RCA: 195] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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Abstract
Adolescence is a critical transition period, during which fundamental changes prepare the adolescent for becoming an adult. Heuristic models of the neurobiology of adolescent behavior have emerged, promoting the central role of reward and motivation, coupled with cognitive immaturities. Here, we bring focus to two basic sets of processes, attention and conditioning, which are essential for adaptive behavior. Using the dual-attention model developed by Corbetta and Shulman (2002), which identifies a stimulus-driven and a goal-driven attention network, we propose a balance that favors stimulus-driven attention over goal-driven attention in youth. Regarding conditioning, we hypothesize that stronger associations tend to be made between environmental cues and appetitive stimuli, and weaker associations with aversive stimuli, in youth relative to adults. An attention system geared to prioritize stimulus-driven attention, together with more powerful associative learning with appetitive incentives, contribute to shape patterns of adolescent motivated behavior. This proposed bias in attention and conditioning function could facilitate the impulsive, novelty-seeking and risk-taking behavior that is typical of many adolescents.
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Abstract
PURPOSE The purpose of this article is to outline notable alterations occurring in the adolescent brain, and to consider potential ramifications of these developmental transformations for public policy and programs involving adolescents. METHODS Developmental changes in the adolescent brain obtained from human imaging work are reviewed, along with results of basic science studies. RESULTS Adolescent brain transformations include both progressive and regressive changes that are regionally specific and serve to refine brain functional connectivity. Along with still-maturing inhibitory control systems that can be overcome under emotional circumstances, the adolescent brain is associated with sometimes elevated activation of reward-relevant brain regions, whereas sensitivity to aversive stimuli may be attenuated. At this time, the developmental shift from greater brain plasticity early in life to the relative stability of the mature brain is still tilted more toward plasticity than seen in adulthood, perhaps providing an opportunity for some experience-influenced sculpting of the adolescent brain. CONCLUSIONS Normal developmental transformations in brain reward/aversive systems, areas critical for inhibitory control, and regions activated by emotional, exciting, and stressful stimuli may promote some normative degree of adolescent risk taking. These findings have a number of potential implications for public policies and programs focused on adolescent health and well-being.
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Affiliation(s)
- Linda Patia Spear
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, New York.
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Moore EM, Forrest RD, Boehm SL. Genotype modulates age-related alterations in sensitivity to the aversive effects of ethanol: an eight inbred strain analysis of conditioned taste aversion. GENES, BRAIN, AND BEHAVIOR 2013; 12:70-7. [PMID: 23171343 PMCID: PMC3553292 DOI: 10.1111/gbb.12004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 10/18/2012] [Accepted: 11/15/2012] [Indexed: 02/04/2023]
Abstract
Adolescent individuals display altered behavioral sensitivity to ethanol, which may contribute to the increased ethanol consumption seen in this age-group. However, genetics also exert considerable influence on both ethanol intake and sensitivity. Currently there is little research assessing the combined influence of developmental and genetic alcohol sensitivities. Sensitivity to the aversive effects of ethanol using a conditioned taste aversion (CTA) procedure was measured during both adolescence (P30) and adulthood (P75) in eight inbred mouse strains (C57BL/6J, DBA/2J, 129S1/SvImJ, A/J, BALB/cByJ, BTBR T(+) tf/J, C3H/HeJ and FVB/NJ). Adolescent and adult mice were water deprived, and subsequently provided with access to 0.9% (v/v) NaCl solution for 1 h. Immediately following access mice were administered ethanol (0, 1.5, 2.25 and 3 g/kg, ip). This procedure was repeated in 72 h intervals for a total of five CTA trials. Sensitivity to the aversive effects of ethanol was highly dependent upon both strain and age. Within an inbred strain, adolescent animals were consistently less sensitive to the aversive effects of ethanol than their adult counterparts. However, the dose of ethanol required to produce an aversion response differed as a function of both age and strain.
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Affiliation(s)
- Eileen M. Moore
- Center for Development and Behavioral Neuroscience, Department of Psychology, Binghamton University – SUNY Binghamton, 4400 Vestal Parkway East, Binghamton, NY 13902, USA
- Indiana Alcohol Research Center, Psychobiology of Addictions, Department of Psychology, Purdue School of Science, IUPUI, 402 N. Blackford Street, LD 124, Indianapolis, IN 46202, USA
| | - Robert D. Forrest
- Indiana Alcohol Research Center, Psychobiology of Addictions, Department of Psychology, Purdue School of Science, IUPUI, 402 N. Blackford Street, LD 124, Indianapolis, IN 46202, USA
| | - Stephen L. Boehm
- Indiana Alcohol Research Center, Psychobiology of Addictions, Department of Psychology, Purdue School of Science, IUPUI, 402 N. Blackford Street, LD 124, Indianapolis, IN 46202, USA
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Conditioned taste aversion and drugs of abuse: History and interpretation. Neurosci Biobehav Rev 2012; 36:2193-205. [DOI: 10.1016/j.neubiorev.2012.08.004] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 08/03/2012] [Accepted: 08/09/2012] [Indexed: 12/16/2022]
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Arrant AE, Jemal H, Kuhn CM. Adolescent male rats are less sensitive than adults to the anxiogenic and serotonin-releasing effects of fenfluramine. Neuropharmacology 2012; 65:213-22. [PMID: 23103347 DOI: 10.1016/j.neuropharm.2012.10.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 10/14/2012] [Accepted: 10/18/2012] [Indexed: 11/30/2022]
Abstract
Risk taking behavior increases during adolescence, which is also a critical period for the onset of drug abuse. The central serotonergic system matures during the adolescent period, and its immaturity during early adolescence may contribute to adolescent risk taking, as deficits in central serotonergic function have been associated with impulsivity, aggression, and risk taking. We investigated serotonergic modulation of behavior and presynaptic serotonergic function in adult (67-74 days old) and adolescent (28-34 days old) male rats. Fenfluramine (2 mg/kg, i.p.) produced greater anxiogenic effects in adult rats in both the light/dark and elevated plus maze tests for anxiety-like behavior, and stimulated greater increases in extracellular serotonin in the adult medial prefrontal cortex (mPFC) (1, 2.5, and 10 mg/kg, i.p.). Local infusion of 100 mM potassium chloride into the mPFC also stimulated greater serotonin efflux in adult rats. Adult rats had higher tissue serotonin content than adolescents in the prefrontal cortex, amygdala, and hippocampus, but the rate of serotonin synthesis was similar between age groups. Serotonin transporter (SERT) immunoreactivity and SERT radioligand binding were comparable between age groups in all three brain regions. These data suggest that lower tissue serotonin stores in adolescents limit fenfluramine-stimulated serotonin release and so contribute to the lesser anxiogenic effects of fenfluramine.
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Affiliation(s)
- Andrew E Arrant
- Department of Pharmacology & Cancer Biology, Duke University, Room 100B Research Park Building 2, Box 3813, Duke University Medical Center, Durham, NC 27710, USA
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Anker JJ, Baron TR, Zlebnik NE, Carroll ME. Escalation of methamphetamine self-administration in adolescent and adult rats. Drug Alcohol Depend 2012; 124:149-53. [PMID: 22305912 PMCID: PMC3767129 DOI: 10.1016/j.drugalcdep.2012.01.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 12/16/2011] [Accepted: 01/06/2012] [Indexed: 11/29/2022]
Abstract
BACKGROUND Methamphetamine (METH) use has increased substantially in the last 10 years and poses a serious health concern, especially for young populations. Drug abuse primarily begins during adolescence, when uninhibited and excessive and drug intake is a common occurrence; thus, understanding the developmental patterns of addiction during this critical period is an essential step in its prevention. In the present study, the effect of age on the vulnerability to METH abuse was examined using a rat model of bingeing (i.e., escalation). METHODS Adolescent and adult rats were compared during short (ShA, 2-h) and long-access (LgA, 6-h) to METH self-administration. On postnatal (PN) days 23 (adolescents) and 90 (adults), rats were implanted with i.v. catheters and trained to lever press for infusions of METH (0.05mg/kg) during 2-h sessions. Once the rats reached a steady rate of METH self-administration, they were divided into ShA or LgA groups and allowed to self-administer METH for 15 additional days. RESULTS Results indicated that adolescent rats earned significantly more infusions than adults under the LgA condition, but the age groups did not differ during ShA. Adolescents, but not adults, also significantly increased (i.e., escalated) METH self-administration across the 15 days of testing under the LgA condition. Further analysis indicated excessive responding during infusions in the LgA METH-exposed adolescents compared to the other groups, suggesting elevated impulsivity or motivation for drug. CONCLUSION These results demonstrate that adolescents are more vulnerable to the escalation of METH than adults during LgA.
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Affiliation(s)
- Justin J. Anker
- Corresponding author. Tel.: +1 612 626 6301; fax: +1 612 624 8935
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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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Wiley JL, Evans RL, Grainger DB, Nicholson KL. Locomotor activity changes in female adolescent and adult rats during repeated treatment with a cannabinoid or club drug. Pharmacol Rep 2012; 63:1085-92. [PMID: 22180350 DOI: 10.1016/s1734-1140(11)70627-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 06/21/2011] [Indexed: 01/21/2023]
Abstract
Adolescents and young adults of both sexes are the primary consumers of "club" drugs; yet, most of the mechanistic preclinical research in this area has been performed in adult male rodents. The purpose of this study was to evaluate the acute and repeated effects of drugs that are commonly abused by adolescents in female adolescent and adult rats in a rodent model of behavioral sensitization. During two five-day periods separated by a two-day break, rats were injected daily with saline or with one of the following drugs: cocaine (7 or 15 mg/kg), ketamine (3 or 10 mg/kg), 3,4-methylenedioxymethamphetamine (MDMA) (3, 10, or 30 mg/kg), or Δ(9)-tetrahydrocannabinol (THC) (0.03, 0.1, 0.3 or 1 mg/kg) and their locomotor activity was measured. Cocaine increased activity across days in both age groups. Whereas ketamine produced progressive increases in activity with repeated administration in rats of both ages, MDMA increased, and then decreased, activity in the chronic dosing regimen in female adolescents only. Tolerance to the initial stimulatory effects of low doses of THC was observed at both ages. The results with THC are similar to those obtained for male rats tested under identical conditions in a previous study; however, in contrast with the present results in females, male adolescent rats in the previous study failed to develop behavioral sensitization to ketamine. Together, these results suggest that age and sex strongly influence the progressive adaptive changes that occur with repeated administration of some, but not all, of these commonly abused substances.
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Affiliation(s)
- Jenny L Wiley
- RTI International, 3040 Cornwallis Road, Research Triangle Park, North Carolina 27709-2194, USA.
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Nasif FJ, Hu XT, Ramirez OA, Perez MF. Inhibition of neuronal nitric oxide synthase prevents alterations in medial prefrontal cortex excitability induced by repeated cocaine administration. Psychopharmacology (Berl) 2011; 218:323-30. [PMID: 21125397 DOI: 10.1007/s00213-010-2105-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 11/18/2010] [Indexed: 01/06/2023]
Abstract
RATIONALE The medial prefrontal cortex (mPFC), a forebrain region that regulates cognitive function and reward-motivated behaviors, has been implicated in the neuropathological mechanisms of drug addiction and withdrawal. In cocaine-abstinent human addicts, neuronal activity of the mPFC is increased in response to cocaine re-exposure or drug-associated cues. Additionally, repeated cocaine exposure alters the membrane properties and ion channel function of mPFC pyramidal neurons in drug-withdrawn rats, leading to an increased firing in response to excitatory stimuli. Nitric oxide (NO), a diffusible neuromodulator of neuronal excitability, may play a role in initiating and maintaining behavioral effects of psychostimulants. However, the role of NO in the mechanisms by which cocaine affects membrane excitability is not well clarified. OBJECTIVES In this study, we attempted to determine whether inhibition of neuronal nitric oxide synthase (nNOS) altered the changes induced by repeated cocaine exposure and withdrawal. METHODS Visualized whole-cell current clamp recordings in brain slices containing the mPFC of rats administered (once per day for 5 days) with either vehicle (10% Cremophor EL in saline 0.9%), cocaine (15 mg/kg, i.p.), or cocaine and the nNOS inhibitor 7-NI (50 mg/kg, i.p.) were employed. RESULTS We found that nNOS inhibition prevented cocaine sensitization and the increased membrane excitability of pyramidal cells, evidenced by an increased number of evoked spikes and reductions in inward rectification observed after short-term withdrawal from cocaine. CONCLUSIONS These findings suggest that NO plays an important role in chronic cocaine-induced deregulation of the mPFC activity that may contribute to the development of behavioral sensitization and cocaine withdrawal.
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Affiliation(s)
- Fernando J Nasif
- Departamento de Farmacología, Facultad de Ciencias Químicas, UNC, IFEC, CONICET, Haya de la Torre y Medina Allende s/n, 5000 Córdoba, Argentina
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Spear LP. Rewards, aversions and affect in adolescence: emerging convergences across laboratory animal and human data. Dev Cogn Neurosci 2011; 1:392-400. [PMID: 21918675 DOI: 10.1016/j.dcn.2011.08.001.rewards] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
The adolescent transition is associated with increases in reward- and sensation-seeking, peer-directed social interactions, and risk-taking, with exploratory use of alcohol and other drugs often beginning at this time. These age-related behaviors may have biological roots embedded in the evolutionary past, with similar adolescent-typical characteristics evident across a variety of mammalian species. Drawing across human behavioral and fMRI data and studies conducting in laboratory animals, this review examines processing of rewards, aversions, and affect in adolescence. Evidence for both hyper- and hypo-reactivity during adolescence in the processing of rewards is reviewed, along with possible contributors to these differences. Indications of sometimes heightened reward reactivity during adolescence are contrasted with frequent attenuations in adolescent sensitivity to aversive stimuli. At the same time, adolescents appear particularly prone to becoming emotionally aroused, especially in social contexts. Emerging evidence hints that exaggerated adolescent reactivity in reward and affective systems may be promoted in part by unusual strong cross-reactivity between these systems during adolescence. Such age-related propensities may promote adolescent risk taking, especially in social and exciting contexts, and contribute to adolescent-typical propensities to attach greater benefit and less cost to risky behaviors such as alcohol and drug use than individuals at other ages.
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Affiliation(s)
- Linda Patia Spear
- Department of Psychology and Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, NY 12902-6000, USA.
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Fairchild G. The developmental psychopathology of motivation in adolescence. Dev Cogn Neurosci 2011; 1:414-29. [PMID: 22436564 DOI: 10.1016/j.dcn.2011.07.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 07/15/2011] [Accepted: 07/18/2011] [Indexed: 01/12/2023] Open
Abstract
Adolescence is a key period for the emergence of psychopathology, with many psychiatric disorders having their modal age-of-onset during this period. Relative to other periods of the lifespan, susceptibility to a number of psychiatric disorders is greatest during adolescence, particularly in females. In addition, disorders which emerge during adolescence appear to be more enduring and serious than those with a later onset. Although these psychiatric conditions may appear different from each other in terms of their associated behavioral signs or symptoms, this review will argue that they involve common alterations in motivational processes or disturbances in reward processing, although the direction of such changes (hypersensitivity vs. hyposensitivity to reward) and the stage of processing affected (reward anticipation vs. receipt) may differ across broader groupings of disorder. Recent behavioral, neuropsychological and neuroimaging research on reward processing in children, adolescents, and adults with these conditions will be described and evaluated. In addition, this article will consider what these studies tell us about their etiology and highlight gaps in our knowledge base. The review will also attempt to explain why adolescence is a period of elevated risk for the development of psychopathology, by discussing normative changes in reward processing in humans and animals.
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Affiliation(s)
- Graeme Fairchild
- School of Psychology, University of Southampton, Highfield, Southampton, United Kingdom.
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Holstein SE, Spanos M, Hodge CW. Adolescent C57BL/6J mice show elevated alcohol intake, but reduced taste aversion, as compared to adult mice: a potential behavioral mechanism for binge drinking. Alcohol Clin Exp Res 2011; 35:1842-51. [PMID: 21575017 DOI: 10.1111/j.1530-0277.2011.01528.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Binge alcohol drinking during adolescence is a serious health problem that may increase future risk of an alcohol use disorder. Although there are several different procedures by which to preclinically model binge-like alcohol intake, limited-access procedures offer the advantage of achieving high voluntary alcohol intake and pharmacologically relevant blood alcohol concentrations (BACs). Therefore, in the current study, developmental differences in binge-like alcohol drinking using a limited-access cycling procedure were examined. In addition, as alcohol drinking has been negatively correlated with sensitivity to the aversive properties of alcohol, we examined developmental differences in sensitivity to an alcohol-induced conditioned taste aversion (CTA). METHODS Binge-like alcohol consumption was investigated in adolescent (4 weeks) and adult (10 weeks) male C57BL/6J mice for 2 to 4 h/d for 16 days. Developmental differences in sensitivity to an alcohol-induced CTA were examined in adolescent and adult mice, with saline or alcohol (3 or 4 g/kg) repeatedly paired with the intake of a novel tastant (NaCl). RESULTS Adolescent mice showed a significant increase in alcohol intake as compared to adults, with adolescents achieving higher BACs and increasing alcohol consumption over successive cycles of the binge procedure. Conversely, adolescent mice exhibited a dose-dependent reduction in sensitivity to the aversive properties of alcohol, as compared to adult mice, with adolescent mice failing to develop a CTA to 3 g/kg alcohol. Finally, extinction of an alcohol CTA was observed following conditioning with a higher dose of alcohol in adolescent, versus adult, mice. CONCLUSIONS These results indicate that adolescent mice consume more alcohol, per kilogram body weight, than adults in a binge-like model of alcohol drinking and demonstrate a blunted sensitivity to the conditioned aversive effects of alcohol. Overall, this supports a behavioral framework by which heightened binge alcohol intake during adolescence occurs, in part, via a reduced sensitivity to the aversive properties of alcohol.
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Affiliation(s)
- Sarah E Holstein
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7178, USA
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Perez MF, Ford KA, Goussakov I, Stutzmann GE, Hu XT. Repeated cocaine exposure decreases dopamine D₂-like receptor modulation of Ca(2+) homeostasis in rat nucleus accumbens neurons. Synapse 2011; 65:168-80. [PMID: 20665696 DOI: 10.1002/syn.20831] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The nucleus accumbens (NAc) is a limbic structure in the forebrain that plays a critical role in cognitive function and addiction. Dopamine modulates activity of medium spiny neurons (MSNs) in the NAc. Both dopamine D₁-like and D₂-like receptors (including D1R or D(1,5)R and D2R or D(2,3,4)R, respectively) are thought to play critical roles in cocaine addiction. Our previous studies demonstrated that repeated cocaine exposure (which alters dopamine transmission) decreases excitability of NAc MSNs in cocaine-sensitized, withdrawn rats. This decrease is characterized by a reduction in voltage-sensitive Na(+) currents and high voltage-activated Ca(2+) currents, along with increased voltage-gated K(+) currents. These changes are associated with enhanced activity in the D1R/cAMP/PKA/protein phosphatase 1 pathway and diminished calcineurin function. Although D1R-mediated signaling is enhanced by repeated cocaine exposure, little is known whether and how the D2R is implicated in the cocaine-induced NAc dysfunction. Here, we performed a combined electrophysiological, biochemical, and neuroimaging study that reveals the cocaine-induced dysregulation of Ca(2+) homeostasis with involvement of D2R. Our novel findings reveal that D2R stimulation reduced Ca(2+) influx preferentially via the L-type Ca(2+) channels and evoked intracellular Ca(2+) release, likely via inhibiting the cAMP/PKA cascade, in the NAc MSNs of drug-free rats. However, repeated cocaine exposure abolished the D₂R effects on modulating Ca(2+) homeostasis with enhanced PKA activity and led to a decrease in whole-cell Ca(2+) influx. These adaptations, which persisted for 21 days during cocaine abstinence, may contribute to the mechanism of cocaine withdrawal.
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Affiliation(s)
- Mariela F Perez
- IFEC, CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende s/n, Ciudad Universitaria, 5000 Córdoba, Argentina
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Pautassi RM, Myers M, Spear LP, Molina JC, Spear NE. Ethanol induces second-order aversive conditioning in adolescent and adult rats. Alcohol 2011; 45:45-55. [PMID: 21187242 DOI: 10.1016/j.alcohol.2010.10.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 09/15/2010] [Accepted: 10/12/2010] [Indexed: 12/16/2022]
Abstract
Alcohol abuse and dependence are considered public health problems, with an etiological onset often occurring during late childhood and adolescence, and understanding age-related differences in ethanol sensitivity is important. Low to moderate ethanol doses (0.5 and 2.0 g/kg, intragastrically [i.g.]) induce single-trial, appetitive second-order place conditioning (SOC) in adolescent, but not adult, rats. Recent studies have demonstrated that adolescents may be less sensitive than adults to the aversive properties of ethanol, reflected by conditioned taste aversion. The present study assessed the aversive motivational effects of high-dose ethanol (3.0 and 3.25 g/kg, i.g., for adolescents and adults, respectively) using SOC. Experiment 1 revealed similar blood and brain ethanol levels in adolescent and adult rats given 3.0 and 3.25 g/kg ethanol, respectively. In Experiment 2, animals received ethanol or vehicle paired with intraoral pulses of sucrose (conditioned stimulus 1 [CS1]). After one, two, or three conditioning trials, the rats were presented with the CS1 while in a distinctive chamber (CS2). When tested for CS2 preference, ethanol-treated animals exhibited reduced preference for the CS2 compared with controls. This result, indicative of ethanol-mediated aversive place conditioning, was similar for adolescents and adults; for females and males; and after one, two, or three training trials. In conjunction with previous results, the present study showed that, in adolescent rats subjected to SOC, ethanol's hedonic effects vary from appetitive to aversive as the ethanol dose increases. Adolescent and adult animals appear to perceive the postingestive effects of high-dose ethanol as similarly aversive when assessed by SOC.
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Perez MF, Gabach LA, Almiron RS, Carlini VP, De Barioglio SR, Ramirez OA. Different chronic cocaine administration protocols induce changes on dentate gyrus plasticity and hippocampal dependent behavior. Synapse 2010; 64:742-53. [PMID: 20698030 DOI: 10.1002/syn.20788] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Hippocampus is a limbic structure that participates in learning and memory formation. Specifically the dentate gyrus has been described as a hippocampal subregion with high rates of plasticity and it is targeted by different psychoactive drugs modulating synaptic plasticity. Repeated cocaine administration induces sensitization to the locomotor effects and it is believed that sensitization involves the same mechanisms of drug seeking and relapse. Although, the mechanisms underlying sensitization is not fully understood. In this work we investigated the impact of repeated intraperitoneal administration of cocaine (15 or 20 mg/kg/day along 5 or 15 days respectively; and 15 mg/kg/day along 5 day followed by a challenge dose after three days of withdrawal) on the dentate gyrus synaptic plasticity, differentiating between sensitized and nonsensitized rats. Furthermore, we correlated changes on the hippocampal synaptic plasticity to memory retention. Our results revealed that the prevalence of cocaine sensitization (around 50%) was identical in all protocols used. The results found in the threshold to generate LTP were similar for all protocols used, being the threshold values cocaine-treated groups (sensitized and nonsensitized) significantly reduced compared to controls, observing the highest reduction in the sensitized group. Moreover, we observed a facilitated retention of recent memory formation only in sensitized animals the nonsensitized subjects remained at the control levels. In conclusion, sensitization to cocaine generates a high efficiency of hippocampal synaptic plasticity that may underlie the aberrant engagement of learning processes occurred during drug addiction.
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Affiliation(s)
- M F Perez
- IFEC, Conicet, Departamento de Farmacologia, Facultad de Ciencias Quimicas, Unc, Haya de la Torre Y Medina Allende, 5000, Cordoba, Argentina.
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Riley AL. The paradox of drug taking: the role of the aversive effects of drugs. Physiol Behav 2010; 103:69-78. [PMID: 21118698 DOI: 10.1016/j.physbeh.2010.11.021] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 10/25/2010] [Accepted: 11/17/2010] [Indexed: 10/18/2022]
Abstract
In 1991, Woods described the paradoxical nature of eating, specifically, that it produced aversive and negative effects. He noted in this analysis the multiple physiological and behavior adaptations, both learned and unlearned, that were aimed at regulating food intake and reducing its aversive, disruptive effects. From this position, he argued that consumption reflected a balance of the positive and aversive effects of eating. The present review extends this analysis to drug use and abuse, i.e., that drug taking itself also is a balance of reward and aversion. Although traditionally the analysis of drug use and abuse has focused on a drug's positive and negative rewarding effects, the present review highlights the aversive effects of these same drugs, e.g., cocaine, morphine, alcohol, and describes such effects as protective in nature. This balance and the manner by which it can be impacted by subject and experiential factors are described with a focus on genetic models of drug abuse using the Lewis and Fischer inbred rat strains.
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Affiliation(s)
- Anthony L Riley
- Psychopharmacology Laboratory, Department of Psychology, American University, Washington, DC 20016, USA.
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Acevedo MB, Molina JC, Nizhnikov ME, Spear NE, Pautassi RM. High ethanol dose during early adolescence induces locomotor activation and increases subsequent ethanol intake during late adolescence. Dev Psychobiol 2010; 52:424-40. [PMID: 20373327 DOI: 10.1002/dev.20444] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adolescent initiation of ethanol consumption is associated with subsequent heightened probability of ethanol use disorders. The present study examined the relationship between motivational sensitivity to ethanol initiation in adolescent rats and later ethanol intake. Experiment 1 determined that ethanol induces locomotor activation shortly after administration but not if tested at a later post-administration interval. In Experiment 2, adolescent rats were assessed for ethanol-induced locomotor activation on postnatal Day 28. These animals were then evaluated for ethanol-mediated conditioned taste aversion and underwent a 16-day-long ethanol intake protocol. Ethanol-mediated aversive effects were unrelated to ethanol locomotor stimulation or subsequent ethanol consumption patterns. Ethanol intake during late adolescence was greatest in animals initiated to ethanol earliest at postnatal Day 28. Females that were more sensitive to ethanol's locomotor-activating effects showed a transient increase in ethanol self-administration. Blood ethanol concentrations during initiation were not related to ethanol-induced locomotor activation. Adolescent rats appeared sensitive to the locomotor-stimulatory effects of ethanol. Even brief ethanol exposure during adolescence may promote later ethanol intake.
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Affiliation(s)
- María Belén Acevedo
- Instituto de Investigación Médica M. y M., Ferreyra (INIMEC-CONICET), Córdoba C.P 5000, Argentina
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Anderson RI, Varlinskaya EI, Spear LP. Ethanol-induced conditioned taste aversion in male sprague-dawley rats: impact of age and stress. Alcohol Clin Exp Res 2010; 34:2106-15. [PMID: 20860618 DOI: 10.1111/j.1530-0277.2010.01307.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Age-specific characteristics may contribute to the elevation in ethanol intake commonly reported among adolescents compared to adults. This study was designed to examine age-related differences in sensitivity to ethanol's aversive properties using a conditioned taste aversion (CTA) procedure with sucrose serving as the conditioned stimulus (CS). Given that ontogenetic differences in responsiveness to stressors have been previously reported, the role of stressor exposure on the development of CTA was also assessed. METHODS Experiment 1 examined the influence of 5 days of prior restraint stress exposure on the expression of CTA in a 2-bottle test following 1 pairing of a sucrose solution with ethanol. In Experiment 2, the effects of 7 days of social isolation on the development of CTA were observed using a 1-bottle test following multiple sucrose-ethanol pairings. RESULTS This study revealed age-related differences in the development of ethanol-induced CTA. In Experiment 1, adolescents required a higher dose of ethanol than adults to demonstrate an aversion. In Experiment 2, adolescents required not only a higher ethanol dose but also more pairings of ethanol with the sucrose CS. No effects of prior stressor exposure were observed in either experiment. CONCLUSIONS Together, these experiments demonstrate an adolescent-specific insensitivity to the aversive properties of ethanol that elicit CTA, a pattern not influenced by repeated restraint stress or housing in social isolation. This age-related insensitivity to the dysphoric effects of ethanol is consistent with other work from our laboratory, adding further to the evidence that adolescent rats are less susceptible to negative consequences of ethanol that may serve as cues to curb consumption.
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Affiliation(s)
- Rachel I Anderson
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, New York 13902-6000, USA
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Schramm-Sapyta NL, DiFeliceantonio AG, Foscue E, Glowacz S, Haseeb N, Wang N, Zhou C, Kuhn CM. Aversive effects of ethanol in adolescent versus adult rats: potential causes and implication for future drinking. Alcohol Clin Exp Res 2010; 34:2061-9. [PMID: 20860614 DOI: 10.1111/j.1530-0277.2010.01302.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Many people experiment with alcohol and other drugs of abuse during their teenage years. Epidemiological evidence suggests that younger initiates into drug taking are more likely to develop problematic drug seeking behavior, including binge and other high-intake behaviors. The level of drug intake for any individual depends on the balance of rewarding and aversive effects of the drug in that individual. Multiple rodent studies have demonstrated that aversive effects of drugs of abuse are reduced in adolescent compared to adult animals. In this study, we addressed 2 key questions: First, do reduced aversive effects of ethanol in younger rats correlate with increased ethanol consumption? Second, are the reduced aversive effects in adolescents attributable to reduced sensitivity to ethanol's physiologic effects? METHODS Adolescent and adult rats were tested for ethanol conditioned taste aversion (CTA) followed by a voluntary drinking period, including postdeprivation consumption. Multivariate regression was used to assess correlations. In separate experiments, adolescent and adult rats were tested for their sensitivity to the hypothermic and sedative effects of ethanol, and for blood ethanol concentrations (BECs). RESULTS We observed that in adolescent rats but not adults, taste aversion was inversely correlated with postdeprivation consumption. Adolescents also exhibited a greater increase in consumption after deprivation than adults. Furthermore, the age difference in ethanol CTA was not attributable to differences in hypothermia, sedation, or BECs. CONCLUSIONS These results suggest that during adolescence, individuals that are insensitive to aversive effects are most likely to develop problem drinking behaviors. These results underscore the importance of the interaction between developmental stage and individual variation in sensitivity to alcohol.
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