The α3β4 nAChR tissue distribution identified by fluorescent α-conotoxin [D11A]LvIA

α 3 β 4, a vital subtype of neuronal nicotinic acetylcholine receptors (nAChRs), is widely distributed in the brain, ganglia, and adrenal glands, associated with addiction and neurological diseases. However, the lack of specific imaging tools for α 3 β 4 nAChRs has hindered the investigation of their tissue distribution and functions. [D11A]LvIA, a peptide derived from marine cone snails, demonstrates high affinity and potency for α 3 β 4 nAChRs, making it a valuable pharmacological tool for studying this receptor subtype. In this study, three fluorescent conjugates of [D11A]LvIA were synthesized using 6-TAMRA-SE (R), Cy3-NHS-ester (Cy3), and BODIPY-FL NHS ester (BDP) dyes. The electrophysiological activities were assessed in Xenopus laevis oocytes by two-electrodes voltage clamp (TEVC). [D11A]LvIA-Cy3 and [D11A]LvIA-BDP show improved selectivity and affinity, with IC 50 values of 512.70 nM and 343.50 nM, respectively, and [D11A]LvIA-Cy3 exhibits better stability in cerebrospinal fluid. Utilizing [D11A]LvIA-Cy3, we successfully visualized the distribution of α 3 β 4 nAChRs in rat trigeminal ganglia, retina, adrenal glands, and various brain regions. This novel fluorescent peptide provides a significant pharmacological tool for the exploration and visualization in-situ distribution of α 3 β 4 nAChRs in different tissues and also assists in clarifying the function.