Desipramine in small doses induces antinociception in the increasing temperature hot-plate test, but not in the tail-flick test.
The data reported for the antinociceptive effect of tricyclic antidepressants are conflicting. In this investigation, the effect of acute intraperitoneal (i.p.) administration of desipramine (2 and 5 mg/kg) was studied in rats, using the tail-flick test with simultaneous measurement of tail-skin temperature, and the increasing temperature hot-plate test. A constant negative correlation between tail-flick latency and tail-skin temperature, as described earlier, was also found in this study. Different ambient temperatures influenced the results of the tail-flick test. At an ambient temperature of 24-25 degrees C, desipramine gave rise to an apparent antinociception in the tail-flick test, which was found to be caused by a relative fall in tail-skin temperature. At 21-22 degrees C, no change in tail-flick latency was found after the administration of desipramine. In the increasing temperature hot-plate test, however, a dose-dependent antinociceptive effect of desipramine was observed at both ambient temperatures. The strong influence of moderate differences in ambient temperature on the results of the tail-flick test may explain some of the conflicting results reported in the literature. Whenever this test is used, the temperature of the tail should be recorded and taken into account in the evaluation of the data.
Lund
A
A
Department of Physiology, University of Bergen, Norway.
Tjølsen
A
A
Hole
K
K
D000818:Animals; D003891:Desipramine / Q000494:pharmacology*; D008297:Male; D009619:Nociceptors / Q000187:drug effects*; D011597:Psychomotor Performance / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects*; D013696:Temperature
D003891:Desipramine