Effects of cysteamine on nociception in mice.
OBJECTIVE
The present study was carried to study the effects of cysteamine on nociception in mice.


METHODS
The pain assays were the hot plate and the tail flick test.


RESULTS
When cysteamine, a drug well known as a somatostatin depletor, was administered 1 and 4 but not 24 h before the tests (hot plate, tail flick), the nociceptive threshold was elevated when the drug was administered at high doses (50 and 100 mg/kg) while at a lower dose (10 mg/kg), it was able to elevate the nociceptive threshold in the hot plate test only. In the hot plate as well the tail flick test cysteamine effects are reversed by naloxone administration and potentiated by morphine administration, whereas neither somatostatin nor cyclo-(7-aminoheptanoyl-Phe-D-Trp-Lys-Thr[Bzl], a reported somatostatin antagonist, changes cysteamine effects.


CONCLUSIONS
These results suggest that cysteamine effects on the nociceptive threshold in the hot plate and tail flick test may be mediated by cysteamine interference with the opioid system.
Capasso
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Department of Pharmaceutical Sciences, University of Salerno, Via Ponte Don Melillo 84084 Fisciano, Salerno, Italy. annacap@unisa.it
Loizzo
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D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D000818:Animals; D003543:Cysteamine / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects*; D017288:Pain Threshold / Q000187:drug effects; D013004:Somatostatin / Q000037:antagonists & inhibitors
D018712:Analgesics, Non-Narcotic; D009270:Naloxone; D013004:Somatostatin; D003543:Cysteamine