Effects of Selective Serotonin Reuptake Inhibitors on the Shock-Induced Ultrasonic Vocalization of Rats in Different Experimental Designs

Abstract Selective serotonin reuptake inhibitors (SSRIs) are widely used for the treatment of depression and anxiety disorders. The major drawback of these compounds is that they ameliorate the symptoms only weeks after the start of the treatment. Contrary to clinical findings, in many cases SSRIs display anxiolytic-like properties in animal models even after a single administration. Anxiety tests based on the foot shock-induced 22-kHz ultrasonic vocalizations in adult rats can be designed with different shocking regimes. SSRIs were ineffective in reducing the emission of aversive ultrasonic vocalizations after acute drug administration in the protocol where animals were shocked soon after the drug treatment. In contrast, SSRIs were efficacious in context-conditioned protocols where shocking occurred on previous days but not on the day of treatment. Intermediate effects were observed in those protocols, where both preshocking and test-day shocking were applied. In the view of these findings, the three experimental protocols can be regarded as different models of anxiety.