Neuroscience 2002 Abstract
| Presentation Number: | 806.2 |
|---|---|
| Abstract Title: | behavioral effects of cocaine and dopamine receptor autoradiography in MOR knockout mice and chronic naltrexone treated mice. |
| Authors: |
Lesscher, H. M. B.*1
; Bossong, M.1
; van der Linden, A. J. A.1
; Spruijt, B. M.2
; Kitchen, I.3
; Bailey, A.3
; Burbach, J. P. H.1
; van Ree, J. M.1
; M.A.F.M. Gerrits1
1Div. Pharm. Anat., RMI, UMC Utrecht, The Netherlands 2Veterinary Fac., Utrecht Univ., The Netherlands 3SBLS, Univ. of Surrey, United Kingdom |
| Primary Theme and Topics |
Neurological and Psychiatric Conditions - Addiction and Drugs of Abuse -- Cocaine |
| Session: |
806. Addiction and drugs of abuse: cocaine VII Poster |
| Presentation Time: | Wednesday, November 6, 2002 2:00 PM-3:00 PM |
| Location: | Hall A2-B3 Z-32 |
| Keywords: | OPIOID, ADDICTION |
Endogenous opioids are thought to mediate reinforcing effects of drugs of abuse like cocaine and ethanol. Opioid antagonists reduce cocaine and ethanol self-administration (SA), whereas chronic treatment with naltrexone (NTX) enhances initiation of cocaine SA. μ-Opioid receptor knockout mice are less sensitive to morphine, ethanol and Δ-THC in SA or CPP. In the present study we investigated interactions between μ-opioid receptors and the mesolimbic dopamine system and the role of μ-opioid receptors in behavioral effects of cocaine. We used MOR knockout mice and chronic NTX mice, a model for opioid receptor upregulation.
Dopamine D1-like, D2-like and D3 receptor number and TH mRNA levels were determined in mesolimbic areas. D1-like receptors were upregulated in striatum of MOR knockout mice. There were no further changes in dopamine parameters in MOR deficient or chronic NTX treated mice. Basal activity and acute effects of cocaine were assessed in MOR knockout mice in an open field. Basal activity of MOR deficient mice was lower compared to wild-type mice. After injection of 10 mg/kg cocaine there was no difference in activity between genotypes. Basal activity in a climbing test was also lower for MOR knockout mice compared to controls.
In conclusion, locomotor activating effects of cocaine are retained in MOR knockout mice, although these mice are hypoactive. The present findings suggest, that mesolimbic dopamine regulation may be altered in MOR deficient mice, but not in chronic NTX mice.
Dopamine D1-like, D2-like and D3 receptor number and TH mRNA levels were determined in mesolimbic areas. D1-like receptors were upregulated in striatum of MOR knockout mice. There were no further changes in dopamine parameters in MOR deficient or chronic NTX treated mice. Basal activity and acute effects of cocaine were assessed in MOR knockout mice in an open field. Basal activity of MOR deficient mice was lower compared to wild-type mice. After injection of 10 mg/kg cocaine there was no difference in activity between genotypes. Basal activity in a climbing test was also lower for MOR knockout mice compared to controls.
In conclusion, locomotor activating effects of cocaine are retained in MOR knockout mice, although these mice are hypoactive. The present findings suggest, that mesolimbic dopamine regulation may be altered in MOR deficient mice, but not in chronic NTX mice.
Supported by NWO/ZON 98510004
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2002 Neuroscience Meeting Planner. Orlando, FL: Society for Neuroscience, 2002. Online.
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