Effects of iontophoretic 5-hydroxytryptamine on the unitary discharge frequency of caudate nucleus neurons in the rat

AbstractSummaryMicroiontophoretic application of 5-hydroxytryptamine (5-HT) on rat caudate nucleus neurons has both facilitatory and inhibitory effects on the discharge frequency of the neurons; in many cases 5-HT has a two-phase action. An analysis was made of the behaviour of facilitatory and inhibitory responses in time considering the mean firing rate variations during and after 5-HT iontophoretic release. Six types of responses have been described : A : short lasting excitation, B : long lasting excitation, C : short lasting inhibition, D : delayed-onset inhibition, E : inhibition followed by excitation, F : excitation followed by inhibition. Also no topographic localization could be m…