title: Dopamine affects the change of pain-related electrical activity induced by morphine dependence.
abstract: Morphine is among the most effective analgesics. However, many evidences suggest that, besides the well-know analgesic activity, repeated opioids treatment can induce some side effects such as dependence, hyperalgesia and tolerance. The mechanism of noxious information transmission in the central nervous system after dependence is not clear. An important neurotransmitter, dopamine (DA) participates not only in the process of opioid dependence but also in pain modulation in the central nervous system. In the present study we observed changes of electrical activities of pain-excitation neurons (PENs) and pain-inhibition neurons (PINs) in the caudate nucleus (Cd) following the development of morphine dependence. We also observed the role of DA on these changes. Our results revealed that both the latency of PEN discharges and the inhibitory duration of PIN discharges decreased, and the net increased values of PEN and PIN discharges increased in the Cd of morphine dependent rats. Those demonstrated that electrical activities of both PENs and PINs increased in morphine dependent rats. DA inhibited the electrical activities of PENs and enhanced those of PINs in morphine dependent rats.
authors.affiliation: Department of Physiology, Harbin Medical University, Xuefu Road, No.194, Harbin 150081, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Fengmin
authors.initials: F
authors.lastname: Zhang
authors.forename: Chunxiao
authors.initials: C
authors.lastname: Yang
authors.forename: Hongbo
authors.initials: H
authors.lastname: Jin
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Yang
authors.forename: Manying
authors.initials: M
authors.lastname: Xu
mesh_terms: D000818:Animals; D002421:Caudate Nucleus / Q000473:pathology / Q000503:physiopathology*; D004298:Dopamine / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D008297:Male; D009021:Morphine Dependence / Q000503:physiopathology*; D009474:Neurons / Q000502:physiology; D010146:Pain / Q000503:physiopathology*; D051381:Rats
chemical_list: D004298:Dopamine