title: [The responses of pain-related neurons in habenula to nociceptive stimuli and morphine].
abstract: OBJECTIVE
  To observe the responses of pain-related neurons in habenula to the nociceptive stimuli and classic analgesic morphine for inquiring into its characteristics of pain.
  
  
  METHODS
  The experiment was proceeded with adult rats under light anesthetized. Through the cannula inserted by operation or the multielectrode injecting the morphine, naloxone, CCK-8 and etc into lateral cerebro-ventricule or habenula, the unit firings from the neurons of habenula were recorded.
  
  
  RESULTS
  The unit firings were recorded from pain-related neurons distributed in MHb or LHb. The pain-related neurons could be differentiated into pain excitatory or pain inhibitory neurons. After the morphine iontophoresed, the main response of the pain excitatory neurons was inhibited, the pain inhibitory neurons were excited. The naloxone iontophoresed could antagonize the analgesic effect of morphine on neurons of habenula. After the morphine injected (10 mg/kg, i. p) into morphine-tolerated rats, the analgesic efficacy of pain-related neurons in LHb was more stronger than in MHb. It showed that the neurons in LHb were suffered from morphine was higher than MHb. After injection of antagonist of CCK-8 into lateral cerebro-ventricle, morphine injected peritoneally could weaken the tolerance level of morphine. Conversely, after injection of morphine (10 mg/kg, i. p.) 10 min, second time injection of CCK-8 (15 ng/10 microl) into lateral cerebro-ventricle could antagonize the analgesic action of morphine on the neurons in LHb, but in MHb the antagonized action was not obviously.
  
  
  CONCLUSIONS
  The excitatory and inhibitory neurons in Hb were sensitive to the nociceptive stimuli and not easy to adapt to it. The sensitivity of the neurons in LHb to morphine was more higher than the neurons in MHb.
authors.affiliation: Department of Physiology, School of Medical Sciences, Jilin University, Changchun 130021, China.
authors.forename: Sui-Sheng
authors.initials: SS
authors.lastname: Wu
authors.forename: Min
authors.initials: M
authors.lastname: Huang
authors.forename: Xiao-Jie
authors.initials: XJ
authors.lastname: Cao
authors.forename: Chun-Xiao
authors.initials: CX
authors.lastname: Zhang
authors.forename: Shao
authors.initials: S
authors.lastname: Wang
mesh_terms: D000818:Animals; D019262:Habenula / Q000166:cytology / Q000187:drug effects*; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D017288:Pain Threshold / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012844:Sincalide / Q000494:pharmacology
chemical_list: D009270:Naloxone; D009020:Morphine; D012844:Sincalide