Differential basal proenkephalin gene expression in dorsal striatum and nucleus accumbens, and vulnerability to morphine self-administration in Fischer 344 and Lewis rats

Martı́n, Sonsoles; Manzanares, Jorge; Corchero, Javier; García-Lecumberri, Carmen; Crespo, José Antonio; Fuentes, José A.; Ambrosio, Emilio

doi:10.1016/s0006-8993(99)01122-1

Cited by 97 publications

(70 citation statements)

References 15 publications

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“…However, the discrepancies could be explained by the differences in the methodology used (the protocol of separation, the peptides measured, cerebral regions vs subregions studied, global vs extracellular levels of peptide measured). In addition, the same relationship between a decrease in PPE mRNAs, in opioid peptides, and the development of morphine dependence was described in Lewis rats (Nylander et al, 1995;Martin et al, 1999).…”

Section: Discussionsupporting

confidence: 53%

Maternal Deprivation Increases Vulnerability to Morphine Dependence and Disturbs the Enkephalinergic System in Adulthood

Vazquez

Penit-Soria²,

Durand³

et al. 2005

J. Neurosci.

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Maternal deprivation can trigger long-lasting molecular and cellular modifications in brain functions and might facilitate the appearance of pathogenic behaviors. This study focuses on the vulnerability to develop morphine dependence in adult rats that were separated from their mother and littermates for 3 h per day for 14 d after birth and examines the adaptive changes in the enkephalinergic pathways. Place-preference conditioning was observed with 2 mg/kg morphine in deprived rats, whereas 5 mg/kg morphine was necessary to induce conditioning in nondeprived animals. A prolonged morphine conditioning was shown in deprived rats. A strong increase in oral morphine self-administration behavior and preference was observed in deprived rats. Only a very slight increase in preference for sucrose solution, a more ethological reinforcer known to interact with the opioid system, was shown in deprived rats. These results indicate that this postnatal environment change leads to a hypersensitivity to the reinforcing properties of morphine and to the development of morphine dependence. A significant decrease in preproenkephalin mRNA expression was observed in the nucleus accumbens and the caudate-putamen nucleus of deprived rats. The basal extracellular levels of the Met-enkephalin-like immunoreactivity in the nucleus accumbens were significantly lower in deprived rats when compared with nondeprived animals, whereas no change in -opioid receptor binding occurred. These results strongly support that maternal deprivation leads to a basal hypoactivity of the enkephalinergic system and hypersensitivity to morphine effects.Together, our results suggest that maternal deprivation in pups likely represents a risk factor for morphine dependence in adult rats.

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Section: Discussionsupporting

confidence: 53%

Maternal Deprivation Increases Vulnerability to Morphine Dependence and Disturbs the Enkephalinergic System in Adulthood

Vazquez

Penit-Soria²,

Durand³

et al. 2005

J. Neurosci.

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“…The relationship between impulsivity and drug abuse vulnerability is known to involve genetic factors, as Lewis rats and rats that have been selectively bred for high saccharin intake (HiS) show both enhanced vulnerability to drug abuse and increased impulsive choice compared to Fischer 344 [2,44,50,83] and rats selectively bred for low saccharin intake (LoS) [14,22,63,64]. The present findings, combined with previous findings showing that IC rats are more vulnerable to drug abuse than EC rats [7,32,82], indicate that environmental factors also influence both impulsivity and drug abuse.…”

Section: Discussionmentioning

confidence: 99%

Impulsive choice and environmental enrichment: Effects of d-amphetamine and methylphenidate

Perry

Stairs

Bardo

2008

Behavioural Brain Research

123

114

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Individual differences in impulsive choice and rearing in differential environments are factors that predict vulnerability to drug abuse. The present study determined if rearing influences impulsive choice, and if d-amphetamine or methylphenidate alters impulsive choice in differentially-reared rats. Male Sprague-Dawley rats were raised from 21 days of age in either an enriched condition (EC) or an isolated condition (IC) and were tested as young adults on an adjusting delay task. In this task, two levers were available and a response on one lever yielded one 45 mg food pellet immediately, whereas a response on the other yielded three pellets after an adjusting delay. The delay was initially set at 6 sec, and it decreased or increased by 1 sec following responses on the immediate or delayed levers, respectively. A mean adjusted delay (MAD) was calculated upon completion of each daily session, and it served as the quantitative measure of impulsivity. Once MADs stabilized, rats were injected with saline, d-amphetamine (0.5, 1.0, or 2.0 mg/kg, s.c.), or methylphenidate (2.5, 5.0, or 10.0 mg/kg, s.c.) 15 min prior to adjusting delay sessions. EC rats had higher baseline MADs (were less impulsive) than IC rats. Additionally, administration of d-amphetamine, but not methylphenidate, dose-dependently increased impulsive choice (decreased MADs) in EC rats. In IC rats, d-amphetamine and methylphenidate dose-dependently decreased impulsivity (increased MADs). These results indicate that rearing environment influences impulsive choice and moderates the effect of psychostimulants on impulsive choice. Specifically, psychostimulants may decrease environment-dependent impulsive choice in individuals with high levels of impulsivity (e.g., those with ADHD), whereas they may increase impulsive choice in individuals with low levels of impulsivity.

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“…Impulsivity is related to drug addiction by studies reporting that rats that are intolerant of reward delay subsequently acquire cocaine self-administration more rapidly and at lower doses (Perry et al, 2005) and also self-administer more alcohol (Poulos et al, 1995(Poulos et al, , 1998 than do delaytolerant rats (for review, see Olmstead, 2006). In addition, Lewis rats, as compared to Fischer rats, exhibit more intolerance to reward delay (Anderson and Woolverton, 2005) and more readily self-administer drugs of abuse, including cocaine (Kosten et al, 1997;Haile and Kosten, 2001), morphine (Ambrosio et al, 1995;Martin et al, 1999), and alcohol (Suzuki et al, 1988). In humans, the trait of impulsivity has been proposed to predispose vulnerability to drug abuse (Zuckerman, 1993;Jentsch and Taylor, 1999;Svrakic et al, 1999;Volkow and Fowler, 2000;Kreek et al, 2005) and there is evidence that impulsivity, as measured by selfreports in humans, is higher in alcohol-dependent patients (Patton, et al, 1995;Chen et al, 2007), and in drug abusers (Allen et al, 1998;Fillmore and Rush, 2002), while recent evidence implicates impulsivity is an important feature of early-onset alcoholism (Dom et al, 2006a, b).…”

Section: Vulnerability To Impulsivitymentioning

confidence: 99%

Behavioral characteristics and neurobiological substrates shared by Pavlovian sign-tracking and drug abuse

Tomie

Grimes

Pohorecky

2008

Brain Research Reviews

153

134

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Drug abuse researchers have noted striking similarities between behaviors elicited by Pavlovian signtracking procedures and prominent symptoms of drug abuse. In Pavlovian sign-tracking procedures, repeated paired presentations of a small object (conditioned stimulus, CS) with a reward (unconditioned stimulus, US) elicits a conditioned response (CR) that typically consists of approaching the CS, contacting the CS, and expressing consummatory responses at the CS. Signtracking CR performance is poorly controlled and exhibits spontaneous recovery and long-term retention, effects that resemble relapse. Sign-tracking resembles psychomotor activation, a syndrome of behavioral responses evoked by addictive drugs, and the effects of sign-tracking on corticosterone levels and activation of dopamine pathways resemble the neurobiological effects of abused drugs. Finally, the neurobiological profile of individuals susceptible to sign-tracking resembles the pathophysiological profile of vulnerability to drug abuse, and vulnerability to sign-tracking predicts vulnerability to impulsive responding and alcohol self-administration. Implications of sign-tracking for models of drug addiction are considered.

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Differential basal proenkephalin gene expression in dorsal striatum and nucleus accumbens, and vulnerability to morphine self-administration in Fischer 344 and Lewis rats

Cited by 97 publications

References 15 publications

Maternal Deprivation Increases Vulnerability to Morphine Dependence and Disturbs the Enkephalinergic System in Adulthood

Maternal Deprivation Increases Vulnerability to Morphine Dependence and Disturbs the Enkephalinergic System in Adulthood

Impulsive choice and environmental enrichment: Effects of d-amphetamine and methylphenidate

Behavioral characteristics and neurobiological substrates shared by Pavlovian sign-tracking and drug abuse

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