| Abstrakt: |
During experiments on isolated slices slices of rat hippocampus the inhibitory action of ?-aminobutyric acid (GABA) was investigated on the excitation of field CA, pyramidal neurons, together with the effects of bicuculline, penicillin and thiopentone on this process. It was found that GABA effectively and reversibly reduced the amplitude of the antrodomic population spike in the area of both the somata and the dendrites of these cells. The sensitivity of apical dendrites to GABA exceeded that of the somata by one order, increasing in a proximal-distal direction. The somata of pyramidal neurons were marked by pronounced desensitization to GABA. Bicuculline and penicillin acted as GABA antagonists at all the levels of CA, pyramidal cells investigated. Bicuculline blocked the effects of GABA on somata and dendrites in almost equal measure. The antagonistic effects of penicillin were 10 times greater in the pyramidal layer than in the dendritic region. Thiopentone reinforced the inhibitory effects of GABA. The potentiating effects of thiopentone were exerted most strongly on the dendrites. It is postulated that the membrane of field CA, neurons contain two types of bicuculline-sensitive GABA receptors, differing in their location (mainly on the cell body or dendrite), their pharmacology, and degree of desensitization to GABA. |
Full text from SpringerLink