The effect of morphine tolerance dependence and abstinence on immunoreactive dynorphin (1-13) levels in discrete brain regions, spinal cord, pituitary gland and peripheral tissues of the rat.
The effect of morphine tolerance dependence and protracted abstinence on the levels of dynorphin (1-13) in discrete brain regions, spinal cord, pituitary gland and peripheral tissues was determined in male Sprague-Dawley rats. Of all the tissues examined, the highest level of dynorphin (1-13) was found to be in the pituitary gland. Among the brain regions and spinal cord examined, the levels of dynorphin (1-13) in descending order were: hypothalamus, spinal cord, midbrain, pons and medulla, hippocampus, cortex, amygdala and striatum. The descending order for the levels of dynorphin (1-13) in peripheral tissues was: adrenals, heart and kidneys. In morphine tolerant rats, the levels of dynorphin (1-13) increased in amygdala but were decreased in pons and medulla. In morphine abstinent rats, the levels of dynorphin (1-13) were increased in amygdala, hypothalamus and hippocampus. The levels of dynorphin (1-13) were increased in pituitary but decreased in spinal cord and remained so even during protracted abstinence. The levels of dynorphin (1-13) in the peripheral tissues of morphine tolerant rats were unaffected. However, in the heart and kidneys of morphine abstinent rats, the levels of dynorphin (1-13) were increased significantly. It is concluded that both morphine tolerance and abstinence modify the levels of dynorphin (1-13) in pituitary, central and peripheral tissues. Morphine abstinence differed from non-abstinence process in that there were additional changes (increases) in the levels of dynorphin (1-13) in brain regions (hypothalamus and hippocampus) and peripheral tissues (heart and kidneys) and may contribute to the symptoms of the morphine abstinence syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Pharmacology, College of Medicine, Ohio State University, Columbus 43210.
A K
AK
Rattan
K L
KL
Koo
G A
GA
Tejwani
H N
HN
Bhargava
D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism; D000700:Analgesics / Q000378:metabolism*; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D004361:Drug Tolerance; D004399:Dynorphins / Q000276:immunology / Q000378:metabolism*; D006321:Heart / Q000187:drug effects; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009021:Morphine Dependence / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism; D013375:Substance Withdrawal Syndrome / Q000378:metabolism*
D000700:Analgesics; D010446:Peptide Fragments; C026843:dynorphin (1-13); D004399:Dynorphins; D009020:Morphine