Intrathecal (IT) injection of 20 μg substance P (SP) induced a behavioral syndrome consisting of scratching and biting the flanks (83% and 57%, respectively, of 48 rats), and distress-like vocalization (42% of 26 rats tested) in response to a previously innocuous tactile stimulus with a von Frey fiber (allodynia). These behavioral events following SP were of short latency (1-2 min) and duration (around 10 min). Injection IT of 5 μg, but not 1 μg, of vasoactive intestinal polypeptide (VIP), concurrently with SP, significantly increased the frequency of both scratching and biting bouts over that produced by SP alone. VIP IT alone (1 or 5 μg) did not stimulate scratching-biting, but induced allodynia in a significant proportion of rats.
All Science Journal Classification (ASJC) codes
- Clinical Biochemistry
- Biological Psychiatry
- Behavioral Neuroscience
- Substance P
- Vasoactive intestinal polypeptide