Comparison of the effects of ethylenediamine analogues and gamma-aminobutyric acid on cortical and pallidal neurones.
1 The actions of ethylenediamine (EDA) and structurally related compounds were investigated by microiontophoresis in Wistar rats. 2 EDA inhibited, via a bicuculline-sensitive mechanism, the spontaneous firing rate of all cortical and pallidal cells tested. 3 The results with the analogues suggest that two amine groups are required for this neuronal depressant action whereas a carboxyl grouping is not. N-substitution reduces the depressant effect. The length of the molecule is also critical, more than 3 methylene components seriously reducing its effectiveness. A rigid analogue of EDA, piperazine, was also active. In addition the apparent transport numbers of EDA and gamma-aminobutyric acid (GABA) were calculated, showing a close similarity between the two. 4 The results are discussed wih respect to the possibility that EDA may represent a new class of GABA-mimetics, or may indicate the existence of a novel diamine receptor mediating bicuculline-sensitive inhibition in the rat CNS.
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects*; D005029:Ethylenediamines / Q000494:pharmacology*; D018756:GABA Antagonists; D005917:Globus Pallidus / Q000187:drug effects*; D007478:Iontophoresis; D008297:Male; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D005029:Ethylenediamines; D018756:GABA Antagonists; D005680:gamma-Aminobutyric Acid; D001640:Bicuculline