Modulation of the 5-HT1C receptor-mediated behavior by 5-HT2, but not 5-HT1A, receptor activation.

The effects of 5-HT1A-receptor agonists 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) and gepirone, a 5-HT1A/5-HT2-receptor agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) and a 5-HT2-receptor agonist (+-)1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane ((+/)DOI) on the 5-HT1C-receptor-mediated exploratory hypoactivity in rats, induced by m-trifluoromethylphenylpiperazine (TFMPP) or m-chlorophenylpiperazine (m-CPP), were studied in the open field test. (+/-)DOI attenuated the effects of TFMPP and abolished those of m-CPP (not dose-dependently). 5-MeODMT showed a weak antagonistic action only at one, intermediate dose. The effects of TFMPP or m-CPP were not changed by 8-OH-DPAT or gepirone. At the same time, 8-OH-DPAT, gepirone, 5-MeODMT and (+/-)DOI themselves practically did not change the exploratory activity of rats. The obtained results permit an assumption that a functional interaction exists between 5-HT1C- and 5-HT2-receptors, but not between 5-HT1C- and 5-HT1A-ones.