POLYAMINE DEPRIVATION PROVOKES AN ANTALGIC EFFECT

It is well established that inhibition of putrescine formation using D ,L-2-(difluoromethyl)omithine and feeding a polyamine-deficient diet t ogether with non-absorbable antibiotics (neomycin and metronidazole), prevent almost completely the growth of tumors in rats. A similar regi men given to patients with prostate cancer not only reduced the titer of prostate specific antigen in serum, but surprisingly provoked at th e same time an antalgic effect. This observation led us to study the p otentiation effect of polyamine deprivation on pain threshold in healt hy rats. Animals were fed for 2 weeks with an artificial diet of known polyamine content, in combination with antibiotics and 2-(difluoromet hyl)omithine, and were then submitted to pain stimuli using two models , the Randall-Selitto test and the Tail-Flick test. Polyamine deprivat ion produced in these models an increase in the latency of the respons e, even under conditions which did not produce significant changes of the polyamine concentrations in blood and brain. From these observatio ns, we may conclude that the polyamines play a role in the perception of nociceptive stimuli under physiological conditions.