Mann E ; Enna SJ ;

Brain Res vol. 184 (2)   pp. 367-73, 24 Fev 1980

Bicuculline-sensitive [3H]GABA receptor binding was studied in membrane fractions prepared from vertebrate whole brain or invertebrate cephalic ganglia. In tissue not treated with Triton X-100, a significant amount of bicuculline-displaceable [3H]GABA binding was detected in the brains of all vertebrates studied, with the hagfish brain binding over twice as much [3H]GABA as the spiny dogfish, the next oldest species. All other vertebrates bound similar amounts of [3H]GABA, being one-third to one-fourth that observed in the hagfish. In contrast, after Triton treatment, the hagfish displayed the least amount of bicuculline- sensitive [3H]GABA binding and, under those conditions, the amount of binding observed increased in an evolutionary fashion. No measurable bicuculline-sensitive GABA receptor binding was noted in any invertebrate studied. These results suggest that bicuculline-sensitive GABA receptors are present in the brains of all vertebrates and that during the course of evolution there developed a Triton-sensitive substance(s) whose presence modifies the kinetic properties of this receptor site.

Animal ;  Bicuculline: pharmacology ;  Birds ;  Brain: metabolism ;  Cell Membrane: metabolism ;  Comparative Study ;  Fishes ;  GABA: metabolism ;  Ganglia: metabolism ;  Invertebrates ;  Kinetics ;  Mice ;  Phylogeny ;  Rats ;  Receptors,Drug: drug effects: metabolism ;  Species Specificity ;  Support,U.S.Gov't,P.H.S. ;  Vertebrates ;  66670 ;