The Effects of the Naltrexone Implant on Rodent Social Interactions and Cocaine-Induced Conditioned Place Preference

Mitchem, Leanne D.; Kruschel, Catherine K; Dallman, Elizabeth; Anders, Katie; Czapiga, Megan; Panos, J; Steinpreis, Rhea E.

doi:10.1016/s0091-3057(98)00150-6

Cited by 20 publications

(13 citation statements)

References 29 publications

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“…Work from other laboratories as well as the behavioral effects found in NAL-treated rats in the present study, i.e., a decrease in two motor signs (rearing and grooming episodes) and an increase in numbers of eye-twitches, are in agreement with this hypothesis. Indeed, a similar decrease in bouts of grooming has been reported in rodents with a naltrexone implant (Mitchem et al, 1999), and this behavior was altered together with various social behaviors, such as the latency to initiate contact. A decrease in locomotor activity has also been demonstrated after intravenous injection of NAL in rabbits (Hernandez and Powell, 1983).…”

Section: Possible Significance Of C-fos Expression In the Ce And Sum supporting

confidence: 69%

Is there tonic activity in the endogenous opioid systems? A c-Fos study in the rat central nervous system after intravenous injection of naloxone or naloxone-methiodide

2000

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This study examined the possibility that a tonic activity in the endogenous opioid systems (EO systems) exists in animals under normal conditions. In a first set of experiments, concurrent changes in behavioral responses and in the numbers of c-Fos-like immunoreactive (Fos-LI) neurons in 58 structures of the brain and lumbosacral spinal cord were analyzed in rats after systemic administration of the opioid antagonist naloxone (NAL; 2 mg/kg). Possible roles of the EO systems were inferred from changes in the numbers of Fos-LI neurons between normal rats that received either NAL or the same volume of saline. Free-floating sections were processed immunohistochemically for c-Fos protein using standard avidin-biotin complex methods. After NAL, the numbers of Fos-LI neurons were significantly increased in the area postrema; in the caudal, intermediate, and rostral parts of the nucleus tractus solitarii; in the rostral ventrolateral medulla; in the Kölliker-Fuse nucleus; in the supramammillary nucleus; and in the central nucleus of the amygdala. In a second set of experiments examining changes in c-Fos expression in the latter structures, similar increases were found after NAL but not after an equimolar dose of NAL-methiodide, a preferential, peripherally acting opioid receptor antagonist. Therefore, Fos-LI was likely triggered after blockade of central opioid receptors, but not peripheral opioid receptors, releasing neurons from EO system-mediated inhibition. The results of this study suggest the existence of a tonic activity of the EO systems exerted on a restricted number of brain regions in normal rats. This tonic activity of the EO systems may control part of the neural networks involved in cardiorespiratory functions and in emotional and learning processes.

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Section: Possible Significance Of C-fos Expression In the Ce And Sum supporting

confidence: 69%

Is there tonic activity in the endogenous opioid systems? A c-Fos study in the rat central nervous system after intravenous injection of naloxone or naloxone-methiodide

2000

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“…Despite these conflicting findings, the observation that naloxone significantly attenuated the effects of cocaine in the present study suggests a possible role for endogenous opioid peptides in cocaine's behavioral effects. In support of this possibility, several studies have reported that the opioid antagonist naltrexone reduces cocaine-maintained responding in the self-administration procedure (Ramsey and Van Ree 1991;Ramsey et al 1999), and attenuates cocaine's rewarding effects in the conditioned place preference paradigm (Bilsky et al 1992;Suzuki et al 1992;Mitchem et al 1999).…”

Section: Discussionmentioning

confidence: 94%

Interactions between opioids and cocaine on locomotor activity in rats: influence of an opioid's relative efficacy at the mu receptor

et al. 2003

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“…Beside an involvement of the µ opioid receptor in cocaine-induced sensitisation to toxic effects (Braida et al 1997) there is also evidence that locomotor activity, conditioned motivational, discriminatory, and reinforcing effects of the substance are mediated by opioid systems (Gerrits et al 1995;Houdi et al 1989;Kuzmin et al 1997;Mitchem et al 1999;Rowlett and Spealman 1998;Suzuki et al 1992). However, some studies failed to demonstrate these interactions (Broadbent et al 1995;Schad et al 1995).…”

Section: Discussionmentioning

confidence: 99%

Rewarding effects of ethanol and cocaine in µ opioid receptor-deficient mice

Becker

Grecksch

Kraus

et al. 2002

Naunyn-Schmiedeberg's Archives of Pharmacology

117

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To investigate the role of mu opioid receptors in the reinforcing effects of psychotropic drugs, the voluntary ethanol intake and ethanol- and cocaine-induced conditioned place preference in mu opioid receptor-deficient mice and their wild-type counterpartners was tested. Moreover, dopamine D1 and D2 receptor binding was measured. It was found that ethanol intake was significantly lower in deficient mice. Conditioned place preference in wild-type animals was induced with 5.0 mg/kg cocaine and this dose was ineffective in the knockouts. In this group conditioned place preference occurred after injection of 10.0 mg/kg cocaine. Cocaine induced a similar increase in locomotor activity in both groups of mice. There was no difference in dopamine D1 receptor binding, whereas dopamine D2 receptor binding was significantly lower in the hippocampus of deficient animals. This suggests that interaction between opioid systems and dopaminergic systems may account for the differences in responding to the drugs.

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The Effects of the Naltrexone Implant on Rodent Social Interactions and Cocaine-Induced Conditioned Place Preference

Cited by 20 publications

References 29 publications

Is there tonic activity in the endogenous opioid systems? A c-Fos study in the rat central nervous system after intravenous injection of naloxone or naloxone-methiodide

Is there tonic activity in the endogenous opioid systems? A c-Fos study in the rat central nervous system after intravenous injection of naloxone or naloxone-methiodide

Interactions between opioids and cocaine on locomotor activity in rats: influence of an opioid's relative efficacy at the mu receptor

Rewarding effects of ethanol and cocaine in µ opioid receptor-deficient mice

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