FUNCTIONAL INTERACTION BETWEEN 5-HT1B AND 5-HT1A OR 5-HT2 RECEPTORS IN MICE

To investigate a possible functional interaction between 5-HT1B and 5-HT1A or 5-HT2 receptors we studied the effects of 5-HT1A selective agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and gepirone, of a 5-HT1A/5-HT2 agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) and of a putative 5-HT2 agonist (+/-)1-(2,5-dimethoxy-4-iodophenyl)-2-amino-propane (+/- DOI) on the 5-HT1B receptor-mediated hypothermia induced by m-trifluoromethylphenylpiperazine (TFMPP) (25 mg/kg) or m-chlorophenylpiperazine (m-CPP) (20 mg/kg) in mice. 8-OH-DPAT (1.25-5 mg/kg), gepirone (1.25-5 mg/kg), 5-MeODMT (2-8 mg/kg) and (+/-)DOI (0.5-2 mg/kg) reduced dose-dependently the TFMPP- or m-CPP-induced hypothermia. At the same time 8-OH-DPAT (2.5 and 5 mg/kg, but not 1.25 mg/kg) and gepirone (1.25-5 mg/kg) themselves decreased the body temperature in mice, while 5-MeODMT (2-8 mg/kg) and (+/-)DOI (0.5-2 mg/kg) did not affect it. The present results suggest that a functional interaction exists between 5-HT1B and 5-HT1A or 5-HT2 receptors.