With the aim of obtaining selective ligands of the low affinity binding sites of [3H]-1-[1-(2- thienyl) cyclohexyl] piperidine ([3H] TCP) in the rat cerebellum, oxygen and sulfur atoms were introduced in the TCP structure and derivatives to obtain analogues with a lowered lipophilicity. These compounds, and others already obtained, were assayed comparatively to determine their affinities for three sites labeled with [3H] TCP: one in the forebrain, the ...