clozapine-n-oxide and Cocaine-Related-Disorders

Cocaine-associated environmental cues elicit craving and relapse to cocaine use by recalling the rewarding memory of cocaine. However, the neuronal mechanisms underlying the expression of cocaine-associated memory are not fully understood. Here, we investigated the possible contribution of γ-aminobutyrate (GABA)ergic neurons in the nucleus accumbens (NAc), a key brain region associated with the rewarding and reinforcing effects of cocaine, to the expression of cocaine-associated memory using the conditioned place preference (CPP) paradigm combined with designer receptors exclusively activated by designer drugs (DREADD) technology. The inhibitory DREADD hM4Di was selectively expressed in NAc GABAergic neurons of vesicular GABA transporter-Cre (vGAT-Cre) mice by infusing adeno-associated virus (AAV) vectors. Ex vivo electrophysiological recordings revealed that bath application of clozapine-N-oxide (CNO) significantly hyperpolarized membrane potentials and reduced the number of spikes induced by depolarizing current injections in hM4Di-positive NAc neurons. Additionally, systemic CNO injections into cocaine-conditioned mice 30 min before posttest session significantly reduced CPP scores compared to saline-injected mice. These results indicate that chemogenetic inhibition of NAc GABAergic neurons attenuated the expression of cocaine CPP, suggesting that NAc GABAergic neuronal activation is required for the environmental context-induced expression of cocaine-associated memory.

Topics: Animals; Clozapine; Cocaine; Cocaine-Related Disorders; GABAergic Neurons; Humans; Male; Mice; Mice, Transgenic; Nucleus Accumbens; Patch-Clamp Techniques; Reinforcement, Psychology; Reward; Synaptic Potentials

Glial cells of the central nervous system directly influence neuronal activity by releasing neuroactive small molecules, including glutamate. Long-lasting cocaine-induced reductions in extracellular glutamate in the nucleus accumbens core (NAcore) affect synaptic plasticity responsible for relapse vulnerability.. We transduced NAcore astrocytes with an adeno-associated virus vector expressing hM3D designer receptor exclusively activated by a designer drug (DREADD) under control of the glial fibrillary acidic protein promoter in 62 male Sprague Dawley rats, 4 dominant-negative soluble N-ethylmaleimide-sensitive factor attachment protein receptor mice, and 4 wild-type littermates. Using glutamate biosensors, we measured NAcore glutamate levels following intracranial or systemic administration of clozapine N-oxide (CNO) and tested the ability of systemic CNO to inhibit reinstated cocaine or sucrose seeking following self-administration and extinction training.. Administration of CNO in glial fibrillary acidic protein-hM3D-DREADD transfected animals increased NAcore extracellular glutamate levels in vivo. The glial origin of released glutamate was validated by an absence of CNO-mediated release in mice expressing a dominant-negative soluble N-ethylmaleimide-sensitive factor attachment protein receptor variant in glia. Also, CNO-mediated release was relatively insensitive to N-type calcium channel blockade. Systemic administration of CNO inhibited cue-induced reinstatement of cocaine seeking in rats extinguished from cocaine but not sucrose self-administration. The capacity to inhibit reinstated cocaine seeking was prevented by systemic administration of the group II metabotropic glutamate receptor antagonist LY341495.. DREADD-mediated glutamate gliotransmission inhibited cue-induced reinstatement of cocaine seeking by stimulating release-regulating group II metabotropic glutamate receptor autoreceptors to inhibit cue-induced synaptic glutamate spillover.

Topics: Animals; Astrocytes; Calcium Channels, N-Type; Central Nervous System Agents; Clozapine; Cocaine; Cocaine-Related Disorders; Cues; Dietary Sucrose; Disease Models, Animal; Dopamine Uptake Inhibitors; Drug-Seeking Behavior; Extinction, Psychological; Genetic Therapy; Glutamic Acid; Male; Mice, Transgenic; Nucleus Accumbens; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Receptors, Metabotropic Glutamate; Self Administration; SNARE Proteins

The factors causing the transition from recreational drug consumption to addiction remain largely unknown. It has not been tested whether dopamine (DA) is sufficient to trigger this process. Here we use optogenetic self-stimulation of DA neurons of the ventral tegmental area (VTA) to selectively mimic the defining commonality of addictive drugs. All mice readily acquired self-stimulation. After weeks of abstinence, cue-induced relapse was observed in parallel with a potentiation of excitatory afferents onto D1 receptor-expressing neurons of the nucleus accumbens (NAc). When the mice had to endure a mild electric foot shock to obtain a stimulation, some stopped while others persevered. The resistance to punishment was associated with enhanced neural activity in the orbitofrontal cortex (OFC) while chemogenetic inhibition of the OFC reduced compulsivity. Together, these results show that stimulating VTA DA neurons induces behavioral and cellular hallmarks of addiction, indicating sufficiency for the induction and progression of the disease.

Topics: Animals; Channelrhodopsins; Clozapine; Cocaine; Cocaine-Related Disorders; Conditioning, Operant; Disease Models, Animal; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Dopaminergic Neurons; Food Deprivation; GABA Antagonists; Glutamate Decarboxylase; Limbic System; Mice; Mice, Inbred C57BL; Mice, Transgenic; Receptors, Dopamine D1; Self Administration; Sucrose; Synaptic Transmission; Time Factors