Role of vasopressin in the blockade of the development of morphine tolerance by footshock and psychological stress.
To elucidate the underlying mechanism for the blockade of the development of morphine analgesic tolerance by footshock and psychological stress, we examined the role of arginine vasopressin in this process. Daily pretreatment with intracerebroventricular anti-arginine vasopressin antiserum suppressed the development of tolerance to morphine. The radioimmunoassayable arginine vasopressin content was decreased in the hypothalamus but not in other regions of mouse brain after exposure to an acute footshock or psychological stress. However, this change disappeared after 5 daily repeated treatments. Neither the development of morphine tolerance nor the brain levels of arginine vasopressin were affected by exposure to forced swimming stress. Neither a single nor 5 daily treatments with morphine induced any appreciable changes in arginine vasopressin content. However, morphine in combination with footshock, lowered this content as did, be it insignificantly, the combination of morphine and psychological stress after chronic treatment. Blockade by footshock and psychological stress of the tolerance development was dose-dependently abolished by daily pretreatment with intracerebroventricular arginine vasopressin. These findings suggest that arginine vasopressin plays a critical role in the blockade, by footshock and psychological stress, of the development of analgesic tolerance to morphine.
Yamashiro
O
O
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Nagasaki University, Japan.
Takahashi
M
M
Kaneto
H
H
D000698:Analgesia; D000818:Animals; D001127:Arginine Vasopressin / Q000502:physiology*; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D004361:Drug Tolerance; D004597:Electroshock; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009020:Morphine / Q000494:pharmacology*; D010121:Oxytocin / Q000494:pharmacology; D013315:Stress, Psychological / Q000503:physiopathology*; D013550:Swimming
D001127:Arginine Vasopressin; D010121:Oxytocin; D009020:Morphine