1. GABA B receptor positive allosteric modulators with different efficacies affect neuroadaptation to and self-administration of alcohol and cocaine.
- Author
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de Miguel E, Vekovischeva O, Kuokkanen K, Vesajoki M, Paasikoski N, Kaskinoro J, Myllymäki M, Lainiola M, Janhunen SK, Hyytiä P, Linden AM, and Korpi ER
- Subjects
- Allosteric Regulation, Animals, Baclofen pharmacology, Behavior, Animal drug effects, Benzofurans pharmacology, CHO Cells, Cricetulus, GABA-B Receptor Agonists pharmacology, Humans, Mice, Quinazolinones pharmacology, Rats, Receptors, Glutamate drug effects, Receptors, Glutamate metabolism, Reward, Self Administration, Ventral Tegmental Area cytology, Ventral Tegmental Area drug effects, Central Nervous System Depressants pharmacology, Cocaine pharmacology, Dopamine Uptake Inhibitors pharmacology, Dopaminergic Neurons drug effects, Ethanol pharmacology, GABA Modulators pharmacology, Neuronal Plasticity drug effects, Receptors, GABA-B drug effects
- Abstract
Drugs of abuse induce widespread synaptic adaptations in the mesolimbic dopamine (DA) neurons. Such drug-induced neuroadaptations may constitute an initial cellular mechanism eventually leading to compulsive drug-seeking behavior. To evaluate the impact of GABA
B receptors on addiction-related persistent neuroplasticity, we tested the ability of orthosteric agonist baclofen and two positive allosteric modulators (PAMs) of GABAB receptors to suppress neuroadaptations in the ventral tegmental area (VTA) and reward-related behaviors induced by ethanol and cocaine. A novel compound (S)-1-(5-fluoro-2,3-dihydro-1H-inden-2-yl)-4-methyl-6,7,8,9-tetrahydro-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one (ORM-27669) was found to be a GABAB PAM of low efficacy as agonist, whereas the reference compound (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (rac-BHFF) had a different allosteric profile being a more potent PAM in the calcium-based assay and an agonist, coupled with potent PAM activity, in the [35 S] GTPγS binding assay in rat and human recombinant receptors. Using autoradiography, the high-efficacy rac-BHFF and the low-efficacy ORM-27669 potentiated the effects of baclofen on [35 S] GTPγS binding with identical brain regional distribution. Treatment of mice with baclofen, rac-BHFF, or ORM-27669 failed to induce glutamate receptor neuroplasticity in the VTA DA neurons. Pretreatment with rac-BHFF at non-sedative doses effectively reversed both ethanol- and cocaine-induced plasticity and attenuated cocaine i.v. self-administration and ethanol drinking. Pretreatment with ORM-27669 only reversed ethanol-induced neuroplasticity and attenuated ethanol drinking but had no effects on cocaine-induced neuroplasticity or self-administration. These findings encourage further investigation of GABAB receptor PAMs with different efficacies in addiction models to develop novel treatment strategies for drug addiction., (© 2018 Society for the Study of Addiction.)- Published
- 2019
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