title: Nucleus accumbens hyperpolarization-activated cyclic nucleotide-gated channels modulate methamphetamine self-administration in rats.
abstract: Methamphetamine addiction is believed to primarily result from increased dopamine release and the inhibition of dopamine uptake. Some evidence suggests that hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play important roles in the functional modulation of dopaminergic neurons and the pathophysiology of related diseases. However, little is known about the effects of HCN channels on methamphetamine addiction.
  
  
  
  The present study investigated the role of brain HCN channels in methamphetamine addiction.
  
  
  
  Acute intracerebroventricular (i.c.v.) injection or bilateral intra-accumbens microinjections of non-selective HCN channel blocker ZD7288 (0.3125 and 0.625 μg) significantly reduced both methamphetamine (0.0125 or 0.05 mg/kg/infusion)-induced self-administration under fixed ratio 2 reinforcement and the breakpoint of methamphetamine (0.05 mg/kg/infusion) under progressive ratio reinforcement in rats. Moreover, compared with i.c.v. injection, bilateral intra-accumbens microinjections of ZD7288 exerted stronger inhibitory effects, suggesting that blockade of HCN channels in the nucleus accumbens reduced the reinforcing effects of and motivation for methamphetamine. We also found that ZD7288 (0.625 and 1.25 μg, i.c.v.) significantly decreased methamphetamine (1 mg/kg, intraperitoneal (i.p.))-induced hyperactivity with no effect on the spontaneous activity in rats. Finally, in vivo microdialysis experiments showed that the HCN channel blockade using ZD7288 (0.625 and 1.25 μg, i.c.v.) decreased methamphetamine (1 mg/kg, i.p.)-induced elevation of extracellular dopamine levels in the nucleus accumbens.
  
  
  
  These results indicate that HCN channels in the nucleus accumbens are involved in the reinforcing properties of methamphetamine and highlight the importance of HCN channels in the regulation of dopamine neurotransmission underlying methamphetamine addiction.
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
authors.forename: Dan-Ni
authors.initials: DN
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Song
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
authors.forename: Shu-Zhuo
authors.initials: SZ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing, 100850, China. jinli9802@163.com.
authors.forename: Jin
authors.initials: J
authors.lastname: Li
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002317:Cardiovascular Agents / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D004298:Dopamine / Q000378:metabolism*; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D008694:Methamphetamine / Q000008:administration & dosage*; D017551:Microdialysis; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012646:Self Administration
chemical_list: D002317:Cardiovascular Agents; D000697:Central Nervous System Stimulants; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D011743:Pyrimidines; C082246:ICI D2788; D008694:Methamphetamine; D004298:Dopamine
keywords: Dopamine; Hyperpolarization-activated cyclic nucleotide-gated channels; In vivo microdialysis; Methamphetamine; Nucleus accumbens; Self-administration