Since the pharmacological screening of several lupinyl- and lu lupinyldene derivatives of three-ring systems showed several interesting activities on the C.N.S., new investigations have been undertaken in order to understand the neurochemical mechanisms underlying such activities (influence on the uptake of choline, norepinephrine and serotonin by isolated rat brain synaptosomes). Thus the series of lupinyl derivatives has been completed with N-lupinyl-2-chloroiminodibenzyl and N-lupinyl-2,3-hexamethyleneindole; moreover, for all the three-ring systems so far considered, the corresponding epi-lupinyl- and epi-lupinylidenderivatives have been prepared in order to check the significance of the steric relationships between the quinolizidine ring and the tricyclic systems. The latter compounds differ from those formerly described for the equatorial position (rather than axial) of the methylene or methine group joining the quinolizidine nucleus to the three-ring systems.