Levels of immunoreactive dynorphin A1-13 during development of morphine dependence in rats.
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.
Wan
X W
XW
Research Laboratory of Natural and Synthetic Drugs, College of Pharmacy, Second Military Medical University, Shanghai, China.
Li
W H
WH
Huang
M
M
You
Z D
ZD
Tan
Y X
YX
Lu
C L
CL
Gong
Z H
ZH
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
D010446:Peptide Fragments; C026843:dynorphin (1-13); D004399:Dynorphins