Exploratory hypoactivity induced by m-trifluoromethylphenylpiperazine (TFMPP) and m-chlorophenylpiperazine (m-CPP).

The action of m-trifluoromethylphenylpiperazine (TFMPP) and m-chlorophenylpiperazine (m-CPP), inhibiting the exploratory activity (ambulation and peeping) of the rat was studied in the open field test. The effects of both these drugs were antagonized by mesulergine, metergoline and mianserin, and partly by methysergide. Spiperone showed an antagonistic action in one (mean) dose only. The effects of TFMPP and m-CPP were not antagonized by ipsapirone, gepirone, cyanopindolol, compound 21009, cyproheptadine, ritanserine, ICS 205930, idazoxan or atropine. The lesion produced by p-chloramphetamine attenuated the effects of TFMPP and abolished those of m-CPP. The obtained results permit an assumption that the TFMPP- and m-CPP-induced decrease in the exploratory activity is mediated probably by 5-HT1C receptors.