Studies on long-term potentiation of the population spike component of hippocampal field potential by the tetanic stimulation of the perforant path rats: effects of a dopamine agonist, SKF-38393.
Long-term potentiation of the field potentials recorded in the dentate gyrus of the hippocampus was observed in freely-moving rats by delivering a brief tetanic stimulation to the perforant path, and the effects of the D1 agonist, SKF-38393, on it was investigated. The field potential was divided into two components; excitatory postsynaptic potential (EPSP) and population spike. In Expt. I, synaptic stimulus-response (S-R) relationship, spike S-R relationship, and EPSP-spike (E-S) relationship were plotted. The estimated slope of the regression line in the spike S-R relationship was enhanced after delivery of the tetanic stimulation (10 pulse at 400 Hz), where that in synaptic S-R relationship was not enhanced. The estimated slope of the regression line in the E-S relationship was also enhanced by the tetanic stimulation. In Expt. II, time-dependent change of the field potential after tetanic stimulation was investigated. The population spike was enhanced significantly for about 2 h following tetanic stimulation, while pEPSP did not change significantly. These changes following tetanic stimulation in Expt. I and II were significantly inhibited by previous administration of SKF-38393 (10 mg/kg, i.p.), and the effect of this drug was dose-dependently antagonized by the D1 antagonist, SCH-23390 (0.1, 0.2 and 0.5 mg/kg, i.p.). These results suggest that a brief tetanic stimulation of the perforant path induces long-term potentiation of the population spike without potentiating the synaptic input in the perforant path-dentate synapses, and that potentiation of the population spike is inhibited by the dopaminergic D1 mechanism.
Yanagihashi
R
R
Department of Physiology and Biochemistry, School of Nursing, Chiba University, Japan.
Ishikawa
T
T
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology*; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D003712:Dendrites / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains
D001552:Benzazepines; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine