title: Levels of immunoreactive dynorphin A1-13 during development of morphine dependence in rats.
abstract: OBJECTIVE
  To study the relationship between the levels of immunoreactive dynorphin A1-13 (ir-dynorphin A1-13) and the degree of morphine dependence.
  
  
  METHODS
  The levels of ir-dynorphin A1-13 in discrete brain regions, spinal cord, and plasma in rats were determined by radioimmunoassay, and the degree of morphine dependence was assessed by scoring withdrawal signs on d 3, d 6, and d 12.
  
  
  RESULTS
  Morphine injection s.c. decreased the levels of ir-dynorphin A1-13 in spinal cord, pituitary, and plasma. The levels of ir-dynorphin A1-13 in hippocampus and hypothalamus were increased. No changes in cortex, midbrain, cerebellum, pons, and medulla were observed. With continuous injection of morphine, withdrawal signs scores were increased on d 6, but there was no difference between the scores of d 6 and d 12.
  
  
  CONCLUSIONS
  The changes of the levels of endogenous ir-dynorphin A1-13 in pituitary, spinal cord, and plasma were compatible with the degree of morphine dependence.
authors.affiliation: Research Laboratory of Natural and Synthetic Drugs, College of Pharmacy, Second Military Medical University, Shanghai, China.
authors.forename: X W
authors.initials: XW
authors.lastname: Wan
authors.forename: W H
authors.initials: WH
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Huang
authors.forename: Z D
authors.initials: ZD
authors.lastname: You
authors.forename: Y X
authors.initials: YX
authors.lastname: Tan
authors.forename: C L
authors.initials: CL
authors.lastname: Lu
authors.forename: Z H
authors.initials: ZH
authors.lastname: Gong
mesh_terms: D000818:Animals; D004399:Dynorphins / Q000097:blood / Q000378:metabolism*; D008297:Male; D009021:Morphine Dependence / Q000378:metabolism*; D010446:Peptide Fragments / Q000097:blood / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000378:metabolism*; D013375:Substance Withdrawal Syndrome / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; C026843:dynorphin (1-13); D004399:Dynorphins