Effects of calcitonin injected into various brain areas on pain threshold and Ca2+ in rats.
OBJECTIVE
To study the effects of calcitonin (Cal) injected into different brain areas on pain threshold.


METHODS
The analgesic effects of Cal were investigated in rats by the tail-flick test.


RESULTS
Cal injected into lateral cerebral ventricle (LCV) or periaqueductal gray (PAG) increased obviously the pain threshold to 49 +/- 22% or to 68 +/- 12% (P < 0.01), respectively. When PAG was blocked with lidocaine, the analgesic effect of Cal injected into LCV was lowered 41 +/- 9%. Cal injected into habenula (Hab) decreased the pain threshold to -30 +/- 5% (P < 0.01).


CONCLUSIONS
Cal in different rat brain areas induced different effects on pain responses: analgesia or hyperalgesia, and showed that PAG played an important role in the analgesic effect induced by Cal, and the changing of pain threshold was mediated by the Ca2+ in brain.
Zhao
X P
XP
Department of Physiology, Norman Bethune University of Medical Sciences, Changchun, China.
Wang
S
S
Xia
Y H
YH
D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D000818:Animals; D001693:Biological Transport, Active; D002116:Calcitonin / Q000494:pharmacology*; D002118:Calcium / Q000502:physiology*; D002122:Calcium Chloride / Q000494:pharmacology; D002552:Cerebral Ventricles / Q000502:physiology; D005260:Female; D019262:Habenula / Q000502:physiology; D007267:Injections; D008297:Male; D017288:Pain Threshold / Q000187:drug effects*; D010487:Periaqueductal Gray / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D018712:Analgesics, Non-Narcotic; D002116:Calcitonin; D002122:Calcium Chloride; D002118:Calcium