Frequency-dependent noradrenergic modulation of long-term potentiation in the hippocampus.
Norepinephrine, briefly superfused during high-frequency stimulation of the mossy fibers in the rat hippocampal slice in vitro, produced a reversible increase in the magnitude, duration, and probability of induction of long-term synaptic potentiation in the CA3 subfield. Similar results were obtained with isoproterenol, whereas propranolol or timolol reversibly blocked long-term potentiation. Norepinephrine had little apparent effect on responses obtained during low-frequency stimulation of the mossy fibers. These data suggest that norepinephrine can mediate long-lasting, frequency-dependent modulation of synaptic transmission in the mammalian brain. Furthermore, the results suggest a plausible mechanism for some of the known associative interactions between synaptic inputs to hippocampal neurons.
D000320:Adrenergic Fibers / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects; D013999:Timolol / Q000494:pharmacology
D013999:Timolol; D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine