The 5-HT syndrome and the drug discrimination paradigm in rats: application in behavioral studies on the central 5-HT...

The use of two behavioral tests, the 5-HT motor syndrome in rats and the drug discrimination paradigm for behavioral analysis of the central 5-HT system are discussed. The motor syndrome induced by L-5-HTP in rats is a simple test, allowing the identification of inhibitors of the 5-HT reuptake system and MAO-A. 5-HT-antagonists and 5HT-agonists can also be detected. The degree of selectivity of 5-HT agonists for the 5-HT system can be determined by the use of specific 5-HT-antagonists, or by testing drugs in MAO-inhibited or 5,7-DHT-lesioned animals. The advantages of the drug discrimination paradigm are mainly the low doses of training drugs needed, the objectivity of the test (no observer involved) and the possibility to test for both agonistic and antagonistic activity in the same animals. The drug discrimination paradigm may also contribute to the behavioral differentiation between drugs interacting with 5-HT1, 5-HT2 and possibly tryptamine receptors.