Serotonin-induced population primary afferent depolarisation in vitro: the effects of neonatal capsaicin treatment

• Published in: Brain research 1998-04, Vol.789 (2), p.339-342
• Main Authors: Khasabov, S.G, Lopez-Garcia, J.A, King, A.E
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn - physiology; Biological and medical sciences; Capsaicin; Capsaicin - pharmacology; Dose-Response Relationship, Drug; Electrophysiology; Fundamental and applied biological sciences. Psychology; GABA; gamma-Aminobutyric Acid - pharmacology; Neurons, Afferent - drug effects; Neurons, Afferent - physiology; Nociceptive afferent; Nociceptors - drug effects; Nociceptors - physiology; Osmolar Concentration; Primary afferent depolarization; Rats; Serotonin (5-HT); Serotonin - pharmacology; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Spinal Cord - cytology; Spinal Cord - physiology; Spinal dorsal horn; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(98)00136-X

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 μM 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 μM 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 μM, 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.