title: Posttetanic enhancement of striato-pallidal synaptic transmission.
abstract: The striato (Str)-globus pallidus external segment (GPe) projection plays major roles in the control of neuronal activity in the basal ganglia under both normal and pathological conditions. The present study used rat brain slice preparations to characterize the enhancement of Str-GPe synapses observed after repetitive conditioning stimuli (CS) of Str with the whole cell patch-clamp recording technique. The results show that 1) the Str-GPe synapses have a posttetanic enhancement (PTE) mechanism, which is considered to be a combination of an augmentation and a posttetanic potentiation; 2) the degree of PTE observed in GPe neurons had a wide range and was positively correlated with a wide range of paired-pulse ratios assessed before application of CS; 3) a wide range of CS, from frequencies as low as 2 Hz with as few as 5 pulses to as high as 100 Hz with 100 pulses, could induce PTE; 4) the decay time constant of PTE was dependent on the strength of CS and was prolonged greatly, up to 120 s, when strong CS were applied; and 5) the level of postsynaptic Cl(-) became a limiting factor for the degree of PTE when strong CS were applied. These results imply that Str-GPe synapses transmit inhibitions in a nonlinear activity-weighted manner, which may be suited for scaling timing and force of repeated or sequential body movements. Other possible factors controlling the induction of PTE and functional implications are also discussed.
authors.affiliation: Department of Anatomy and Neurobiology, College of Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Juhyon
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Anatomy and Neurobiology, College of Medicine, The University of Tennessee Health Science Center, Memphis, Tennessee hkita@uthsc.edu.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kita
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D046509:Tissue Culture Techniques
chemical_list: D002121:Calcium Channel Blockers; D002712:Chlorides; D002118:Calcium
keywords: globus pallidus; inhibitory postsynaptic currents; short-term plasticity; striatum