Benzyloxycarbonyl-Methionyl-2(S)-Cyanopyrrolidine, a Prolyl Endopeptidase Inhibitor, Modulates Depression-Like Behavior of Rats in Forced Swimming Test and Activities of Proline-Specific Peptidases in the Brain Structures

High activities of prolyl endopeptidase and dipeptidylpeptidase IV in the striatum and of prolyl endopeptidase in the frontal cortex were recorded in rats with stress-induced depressionlike state (behavioral despair) developed in the Porsolt forced swimming test. Acute injection of benzyloxycarbonyl-methionyl-2(S)-cyanopyrrolidine (prolyl endopeptidase noncompetitive synthetic inhibitor) in a dose of 1 mg/kg prevented the development of behavioral despair and the increase of prolyl endopeptidase and dipeptidylpeptidase IV activities in the brain structures. In a dose of 2 mg/kg prolyl endopeptidase inhibitor did not modify the development of behavioral despair, but prevented the increase of prolyl endopeptidase and dipeptidylpeptidase IV activities in the striatum.