Region specific increase of dopamine receptor D1/D2 mRNA expression in the brain of μ-opioid receptor knockout mice

Park, Younjoo; Ho, Ing K.; Fan, Lir Wan; Loh, Horace H.; Ko, Kwang Ho

doi:10.1016/s0006-8993(01)02001-7

Cited by 31 publications

(19 citation statements)

References 24 publications

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“…Thus, it might actually be changes in both the D2 receptor and the CB 1 receptor that reduce alcohol rewarding effects and alcohol self-administration in the CB 1 À/À mice. Similar results have been found in the m-opioid receptor knockout mice that also exhibited increased D2 receptor expression and decreased ethanol-CPP (Roberts et al, 2000; Park et al, 2001;Tien et al, 2003). There is strong evidence of involvement of the D2 receptor in the behavioral effects of ethanol.…”

Section: Discussionsupporting

confidence: 73%

CB1 Receptor Knockout Mice Display Reduced Ethanol-Induced Conditioned Place Preference and Increased Striatal Dopamine D2 Receptors

Houchi

Babovic

Pierrefiche

et al. 2004

Neuropsychopharmacol

173

145

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Cannabinoids and ethanol activate the same reward pathways, and recent advances in the understanding of the neurobiological basis of alcoholism suggest that the CB 1 receptor system may play a key role in the reinforcing effects of ethanol and in modulating ethanol intake. In the present study, male CB 1 receptors knockout mice generated on a CD1 background displayed decreased ethanol-induced conditioned place preference (CPP) compared to wild-type (CB 1 þ / þ ) mice. Ethanol (0.5, 1.0, 1.5, and 2.0 g/kg) induced significant CPP in CB 1 þ / þ mice at all doses tested, whereas it induced significant CPP only at the highest dose of ethanol (2.0 g/kg) in CB 1 À/À mice.However, there was no genotypic difference in cocaine (20 mg/kg)-induced CPP. There was also no genotypic difference, neither in cocaine (10-50 mg/kg) nor in D-amphetamine (1.2-5 mg/kg)-induced locomotor effects. In addition, mutant and wild-type mice did not differ in sensitivity to the anxiolytic effects of ethanol (1.5 g/kg) when tested using the elevated plus maze. Interestingly, this decrease in ethanol efficacy to induce CPP in CB 1 À/À mice was correlated with an increase in D2/D3 receptors, as determined by [ 3 H]raclopride binding, whereas there was no difference in D1-like receptors, as determined by [ 3 H]SCH23390 binding, measured in the striatum from drug-naïve mice. This increase in D2/D3 binding sites observed in CB 1 knockout mice was associated with an altered locomotor response to the D2/D3 agonist quinpirole (low doses 0.02-0.1 mg/kg) but not to an alteration of quinpirole (0.1-1.0 mg/kg)-induced CPP compared to wild-type mice. Altogether, the present results indicate that lifelong deletion of CB 1 receptors reduced ethanol-induced CPP and that these reduced rewarding effects of ethanol are correlated to an overexpression of striatal dopamine D2 receptors.

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Section: Discussionsupporting

confidence: 73%

CB1 Receptor Knockout Mice Display Reduced Ethanol-Induced Conditioned Place Preference and Increased Striatal Dopamine D2 Receptors

Houchi

Babovic

Pierrefiche

et al. 2004

Neuropsychopharmacol

173

145

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“…These genetically manipulated mice provide a powerful means of revealing the function of opioid receptors in vivo. However, functionally compensatory alterations in other neurotransmitter systems found in gene knockout mice [14,36,37] may sometimes complicate the outcome or even mislead the interpretation. Therefore, it is more important and necessary to determine the effects of pharmacological manipulation on genetically normal subjects in terms of potential clinical relevance.…”

Section: Discussionmentioning

confidence: 99%

Attenuation of methamphetamine-induced behavioral sensitization in mice by systemic administration of naltrexone

Chiu

2005

Brain Research Bulletin

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Repeated intermittent exposure to psychostimulants was found to produce behavioral sensitization. The present study was designed to establish a mouse model and by which to investigate whether opioidergic system plays a role in methamphetamine-induced behavioral sensitization. Mice injected with 2.5 mg/kg of methamphetamine once a day for 7 consecutive days showed behavioral sensitization after challenge with 0.3125 mg/kg of the drug on day 11, whereas mice injected with a lower daily dose (1.25 mg/kg) did not. Mice received daily injections with either 1.25 or 2.5 mg/kg of methamphetamine showed behavioral sensitization after challenge with 1.25 mg/kg of the drug on days 11, 21, and 28. To investigate the role of opioidergic system in the induction and expression of behavioral sensitization, long-acting but non-selective opioid antagonist naltrexone was administrated prior to the daily injections of and challenge with methamphetamine, respectively. Our results show that the expressions of behavioral sensitization were attenuated by pretreatment with 10 or 20 mg/kg of naltrexone either during the induction period or before methamphetamine challenge when they were tested on days 11 and 21. These results indicate that repeated injection with methamphetamine dose-dependently induced behavioral sensitization in mice, and suggest the involvement of opioid receptors in the induction and expression of methamphetamine-induced behavioral sensitization.

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“…Regulation in the other direction has also been described: chronic morphine exposure and spontaneous withdrawal produce reductions in striatal D1 and D2 dopamine receptor mRNA (Georges et al, 1999). In m-opioid receptor knockout mice, dopamine receptor D1/D2 mRNA expression is increased in the striatum (Park et al, 2001). This two-way regulation of dopaminergic D1/D2 and m-opioid receptors, and the responsiveness of RGS-R4 and RGS-R7 mRNA levels to dopaminergic and opioidergic substances (see Introduction and present work), suggests the possibility of dopaminergic control of the facilitatory action of RGS-R7/Gb5 complexes on m-opioid tachyphylaxis and acute tolerance.…”

Section: Rgs-r7 Proteins and Chronic Morphinementioning

confidence: 98%

Expression of Neural RGS-R7 and Gβ5 Proteins in Response to Acute and Chronic Morphine

López-Fando

Rodríguez-Muñoz

Sánchez‐Blázquez

et al. 2004

Neuropsychopharmacol

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The R7 subfamily of regulators of G-protein signaling (RGS) proteins (RGS6, RGS7, RGS9-2, and RGS11), and its binding protein Gb5, are found in neural structures of mouse brain. A single intracerebroventricular priming dose of 10 nmol morphine gave rise to acute tolerance to the analgesic effects of successive identical test doses of the opioid. At 2 h after administering the acute opioid, RGS7 mRNA levels in the striatum plus those of RGS9-2 in the striatum and thalamus were increased, whereas RGS9-2 and RGS11 mRNA were reduced in the cortex. Similar but attenuated RGS-R7 mRNA changes persisted 24 h after acute morphine administration. No changes in Gb5 mRNA levels were observed. At 2 days after commencing sustained morphine treatment, the levels of mRNA for RGS7, RGS9-2, RGS11, and Gb5 increased in most of the brain structures studied (striatum, thalamus, periaqueductal gray matter (PAG), and cortex). In these morphine tolerant-dependent mice, the greater changes were found for RGS9-2 in the thalamus (4500%) and PAG (4200%). In post-dependent mice, the increases in RGS-R7 and Gb5 mRNA still persisted in the PAG and striatum at 8 and 16 days after starting the chronic opioid treatment. The raised mRNA levels promoted by chronic, but not by acute, morphine, were accompanied by increases in the encoded proteins. This is probably a result of the costabilization of the RGS-R7 and Gb5 proteins forming heterodimers. Opioidinduced adaptations of RGS-R7 and Gb5 genes may regulate the severity of morphine-induced tolerance/dependence and the duration of the post-dependent period, helping to recover the normal response.

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Region specific increase of dopamine receptor D1/D2 mRNA expression in the brain of μ-opioid receptor knockout mice

Cited by 31 publications

References 24 publications

CB1 Receptor Knockout Mice Display Reduced Ethanol-Induced Conditioned Place Preference and Increased Striatal Dopamine D2 Receptors

CB1 Receptor Knockout Mice Display Reduced Ethanol-Induced Conditioned Place Preference and Increased Striatal Dopamine D2 Receptors

Attenuation of methamphetamine-induced behavioral sensitization in mice by systemic administration of naltrexone

Expression of Neural RGS-R7 and Gβ5 Proteins in Response to Acute and Chronic Morphine

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