Reduction of [H]muscimol binding sites in rat dorsal spinal cord after neonatal capsaicin treatment

Two-day-old rats were pretreated with 50 mg/kg of capsaicin. After 3–4 months, specific binding of [³H]muscimol and [³H]strychnine was measured in membrane preparations from dorsal spinal cord. A 20–30% decrease of the number of [³H]muscimol binding sites was observed after capsaicin treatment. In contrast, [³H]strychnine binding was unchanged. The results provide indirect evidence for a presynaptic location of GABA receptors on capsaicin-sensitive primary afferent neurons.