Modification of the anabaseine pyridine nucleus allows achieving binding and functional selectivity for the α3β4 nicotinic acetylcholine receptor subtype

We report the design, synthesis and pharmacological screening of a group of analogues of anabaseine 2, a naturally occurring unselective nicotinic agonist. The novel nAChR ligands 5-15 were planned following a molecular modeling analysis which suggested the replacement of the pyridine ring of 2 with a 3- substituted benzene ring as a means to gain selectivity for the a3b4 nAChR subtype. Overall, from binding experiments, the synthesized compounds showed high values of a3b4 affinity and a3b4 vs a4b2 selectivity, although they poorly discriminated the homomeric a7 subtype. The three analogues 6, 12 and 13 were also evaluated in electrophysiological assays, and 12 [6-(3-iodophenyl)-2,3,4,5- tetrahydropyridine] emerged as a rather interesting nicotinic ligand. Indeed, in addition to a noteworthy affinity (Ki ¼ 4.7 nM) for the a3b4 subtype and to an excellent a3b4 vs a4b2 subtype selectivity (806-fold), compound 12 selectively activated the a3b4 nAChR (EC50 ¼ 7.4 mM) while eliciting a negligible response at the a7 subtype and no effect at the a4b2 subtype

GM1 Oligosaccharide Crosses the Human Blood–Brain Barrier In Vitro by a Paracellular Route

International audienceGanglioside GM1 (GM1) has been reported to functionally recover degenerated nervous system in vitro and in vivo, but the possibility to translate GM1's potential in clinical settings is counteracted by its low ability to overcome the blood-brain barrier (BBB) due to its amphiphilic nature. Interestingly, the soluble and hydrophilic GM1-oligosaccharide (OligoGM1) is able to punctually replace GM1 neurotrophic functions alone, both in vitro and in vivo. In order to take advantage of OligoGM1 properties, which overcome GM1's pharmacological limitations, here we characterize the OligoGM1 brain transport by using a human in vitro BBB model. OligoGM1 showed a 20-fold higher crossing rate than GM1 and time-concentration-dependent transport. Additionally, OligoGM1 crossed the barrier at 4 °C and in inverse transport experiments, allowing consideration of the passive paracellular route. This was confirmed by the exclusion of a direct interaction with the active ATP-binding cassette (ABC) transporters using the "pump out" system. Finally, after barrier crossing, OligoGM1 remained intact and able to induce Neuro2a cell neuritogenesis by activating the TrkA pathway. Importantly, these in vitro data demonstrated that OligoGM1, lacking the hydrophobic ceramide, can advantageously cross the BBB in comparison with GM1, while maintaining its neuroproperties. This study has improved the knowledge about OligoGM1's pharmacological potential, offering a tangible therapeutic strategy