Tachykinin receptor (NK 1, NK 2, NK 3) binding sites in the rat caudal brainstem following neonatal capsaicin administration

Abstract

Binding of [ 125I]-Bolton–Hunter substance P ([ 125I]-BHSP), [ 125I]-neurokinin A and [ 3H]-senktide to tachykinin NK 1, NK 2 and NK 3 receptors, respectively, was examined in caudal brainstem sections of 10-week-old rats pretreated as neonates (P2) with capsaicin (50 mg/kg, s.c.) or vehicle. [ 125I]-BHSP binding was localised to the nucleus of the solitary tract (NTS), hypoglossal nucleus and inferior olivary complex, whereas [ 125I]-neurokinin A and [ 3H]-senktide binding were confined to the NTS. The distribution and density of binding sites were similar in vehicle- and capsaicin-pretreated rats, suggesting that sensory neuron ablation by neonatal capsaicin does not affect tachykinin receptor numbers in the rat caudal brainstem.