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Altered architecture and functional consequences of the mesolimbic dopamine system in cannabis dependence

Spiga, Saturnino and Lintas, Alessandra and Migliore, Michele and Diana, Marco (2010) Altered architecture and functional consequences of the mesolimbic dopamine system in cannabis dependence. Addiction Biology, Vol. 15 (3), p. 266-276. eISSN 1369-1600. Article.

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DOI: 10.1111/j.1369-1600.2010.00218.x

Abstract

Cannabinoid withdrawal produces a hypofunction of mesencephalic dopamine neurons that impinge upon medium spiny neurons (MSN) of the forebrain. After chronic treatment with two structurally different cannabinoid agonists, Δ9-tetrahydrocannabinol and CP55 940 (CP) rats were withdrawn spontaneously and pharmacologically with the CB1 antagonist SR141716A (SR). In these two conditions, evaluation of tyrosine hydroxylase (TH)-positive neurons revealed significant morphometrical reductions in the ventrotegmental area but not substantia nigra pars compacta of withdrawn rats. Similarly, confocal analysis of Golgi–Cox-stained sections of the nucleus accumbens revealed a decrease in the shell, but not the core, of the spines' density of withdrawn rats. Administration of the CB1 antagonist SR to control rats, provoked structural abnormalities reminiscent of those observed in withdrawal conditions and support the regulatory role of cannabinoids in neurogenesis, axonal growth and synaptogenesis by acting as eu-proliferative signals through the CB1 receptors. Further, these measures were incorporated into a realistic computational model that predicts a strong reduction in the excitability of morphologically altered MSN, yielding a significant reduction in action potential output. These pieces of evidence support the tenet that withdrawal from addictive compounds alters functioning of the mesolimbic system and provide direct morphological evidence for functional abnormalities associated with cannabinoid dependence at the level of dopaminergic neurons and their postsynaptic counterpart and are coherent with recent hypothesis underscoring a hypodopaminergic state as a distinctive feature of the ‘addicted brain’.

Item Type:Article
ID Code:5968
Status:Published
Refereed:Yes
Uncontrolled Keywords:Cannabinoids, dopamine, nucleus accumbens, THC, VTA, withdrawal
Subjects:Area 05 - Scienze biologiche > BIO/14 Farmacologia
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze del farmaco
Publisher:Blackwell / Wiley
eISSN:1369-1600
Copyright Holders:© 2010 The Authors, Journal compilation © 2010 Society for the Study of Addiction
Deposited On:19 Apr 2011 12:45

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