title: Acetylcholine plays an antinociceptive role by modulating pain-induced discharges of pain-related neurons in the caudate putamen of rats.
abstract: The caudate putamen (CPu) has been suggested to be involved in nociceptive modulation. Some neurotransmitters, including acetylcholine (ACh), participate in pain modulation in the central nervous system. However, the active mechanism of ACh on the pain-related neurons in the CPu remains unclear. This study aimed to investigate the effects of the cholinergic agonists ACh and pilocarpine and the muscarinic ACh receptor antagonist atropine on the pain-induced response of pain-related neurons in the CPu of Wistar rats. Trains of electrical impulses applied to the sciatic nerve of rat were used as the noxious stimulus. The electrical activities of pain-excited neurons (PENs) or pain-inhibited neurons (PINs) in the CPu were recorded by a glass microelectrode. Our results showed that an intra-CPu injection of 4 μg/2 μl ACh or pilocarpine decreased and increased the pain-induced discharge frequency in the PENs and PINs, respectively. Intra-CPu administration of 1 μg/2 μl atropine produced the opposite effect on these neurons. These findings indicate that ACh may play an analgesic role by affecting the electric activities of PENs and PINs, and the muscarinic pathway may be involved in the modulation of pain perception in the CPu.
authors.affiliation: aDepartment of Neurology of Fourth Affiliated Hospital bDepartment of Neurosurgery of First Affiliated Hospital cDepartment of Neurology of Second Affiliated Hospital dLaboratory of Neural Algesia Electrophysiology, Department of Physiology, Harbin Medical University, Harbin, China.
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Li
authors.forename: Da-Ming
authors.initials: DM
authors.lastname: Zhang
authors.forename: Chun-Xiao
authors.initials: CX
authors.lastname: Yang
authors.forename: Xu
authors.initials: X
authors.lastname: Ma
authors.forename: He-Ren
authors.initials: HR
authors.lastname: Gao
authors.forename: Duo
authors.initials: D
authors.lastname: Zhang
authors.forename: Man-Ying
authors.initials: MY
authors.lastname: Xu
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000200:Action Potentials; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002421:Caudate Nucleus / Q000187:drug effects / Q000378:metabolism*; D004558:Electric Stimulation; D008839:Microelectrodes; D018721:Muscarinic Agonists / Q000494:pharmacology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D058748:Pain Perception / Q000187:drug effects; D010862:Pilocarpine / Q000494:pharmacology; D011699:Putamen / Q000187:drug effects / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000378:metabolism; D012584:Sciatic Nerve; D013997:Time Factors
chemical_list: D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D011976:Receptors, Muscarinic; D010862:Pilocarpine; D001285:Atropine; D000109:Acetylcholine