Intrathecal and epidural somatostatin in rats: can antinociception, motor effects and neurotoxicity be separated?

In the present investigation, the antinociceptive, motor blocking and neurotoxic effects of intrathecal and epidural somatostatin (SST) were assessed in rats implanted with lumbar intrathecal and epidural catheters. The doses studied were 5, 7.5, 10, 12.5 and 15 micrograms intrathecally and 100, 250, 400 and 500 micrograms epidurally. It appears that if the intrathecal doses of SST are kept below 15 micrograms and the epidural doses below 250 micrograms, the prolonged tail-flick latency can be separated from the transient motor blockade. The antinociception appears not to be attributable to neurotoxicity by the histological evidence available.