Biphasic time-course of capsaicin-induced substance P depletion: failure to correlate with thermal analgesia in the rat.
Capsaicin (15 or 100 mg/kg, s.c.) produced thermal analgesia in the rat hot plate test (55 degrees C). Capsaicin (100 mg/kg) also caused a reduction in spinal cord substance P levels. However, the time-course of capsaicin-induced depletion of substance P levels does not correlate with the time-course of thermal analgesia. Also, substance P depletion is biphasic, suggesting that more than one mechanism is involved in capsaicin's ability to reduce substance P levels in the spinal cord.
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D006358:Hot Temperature; D008297:Male; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D012684:Sensory Thresholds; D013116:Spinal Cord / Q000032:analysis / Q000503:physiopathology*; D013373:Substance P / Q000032:analysis / Q000502:physiology*
D013373:Substance P; D002211:Capsaicin