1-aminocyclopropanecarboxylates exhibit antidepressant and anxiolytic actions in animal models

1-Aminocyclopropanecarboxylic acid (ACPC) is a high affinity ligand at strychnine-insensitive glycine receptors that exhibits partial agonist properties in both biochemical and electrophysiological measures. While ACPC was reported active in animal models commonly used to evaluate potential antidepressants (forced swim) and anxiolytics (plus-maze), the zwitterionic character of this compound could limit both penetration into the central nervous system and oral availability. The present experiments were designed to determine the duration of action of ACPC, its efficacy following oral administration, and to compare these effects with the more lipophilic ACPC methyl ester. Parenterally and orally administered ACPC were equipotent in reducing immobility in the forced swim test, an action manifested for at least 6 h. Both orally and parenterally administered ACPC methyl ester were approximately 3.3-fold more potent than ACPC in the forced swim test. In the elevated plus-maze, both ACPC and ACPC methyl ester were active for 1-2 h after parenteral administration. These findings suggest that 1-aminocyclopropanecarboxylates may constitute a novel class of antidepressant/anxiolytic agents.