Description
Conditioning stimulation of afferent fibers in hippocampal area CA1 produced heterosynaptic, posttetanic depression (PTD) of responses evoked by stimulation of an independent set of afferent fibers. PTD was present within 5 s of conditioning stimulation, amounted to a 60-80% reduction of excitatory postsynaptic potentials (EPSPs), and required a period of 3-5 min for recovery. Antagonists of A1 adenosine receptors substantially reduced PTD. Adenosine released into, or formed in, the extracellular space during conditioning stimulation may diffuse within the slice to depress evoked release of glutamate.
Subject
Adenosine/*physiology; Afferent/drug effects/physiology; Animals; Dendrites/drug effects/physiology; Electric Stimulation; Evoked Potentials/drug effects/physiology; Hippocampus/cytology/drug effects/*physiology; In Vitro Techniques; Neuronal Plasticity/drug effects/physiology; Neurons; Purinergic Antagonists; Rats; Synapses/drug effects/*physiology; Synaptic Transmission/drug effects/physiology; Theophylline/analogs & derivatives/pharmacology; Xanthines/pharmacology