Serotonin-induced population primary afferent depolarisation in vitro: the effects of neonatal capsaicin treatment.
The effect of 5-hydroxytryptamine (5-HT) on population primary afferent depolarisation (PAD) has been studied using in vitro spinal cord preparations from normal and capsaicin pre-treated (neonatal subcutaneous injection; 75 mg kg-1) rats aged 10-14 days. In preparations from untreated rats, the concentration-response curve for PAD in response to 0.1-100 microM 5-HT was bell-shaped but in the capsaicin pre-treated group, a non-saturating 5-HT-induced PAD concentration-response curve was generated. Quantitatively, the mean PAD responses to 0.1-10 microM 5-HT were of a greater amplitude in the control group compared to the capsaicin pre-treated group (p</=0. 05). For the highest 5-HT concentration of 100 microM, PAD values were significantly greater in the capsaicin pre-treated group (p</=0. 05). These data indicate that control of sensory afferent polarity may involve two 5-HT receptor types and that nociceptive and non-nociceptive afferents may be targets for released 5-HT.
Khasabov
S G
SG
Dept. of Physiology, University of Leeds, Leeds LS2 9NQ, UK.
Lopez-Garcia
J A
JA
King
A E
AE
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D002211:Capsaicin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology*; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D009994:Osmolar Concentration; D051381:Rats; D012701:Serotonin / Q000494:pharmacology*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
D012701:Serotonin; D005680:gamma-Aminobutyric Acid; D002211:Capsaicin