Activation of 5-HT1B receptors suppresses low but not high frequency synaptic transmission in the rat subicular cortex in vitro.
We have shown previously that activation of 5-HT1B serotonin receptors mediates suppression of the amplitude of evoked potentials in the subiculum [2]. Here we show that after application of 5-HT (10 microM), excitatory postsynaptic potentials of subicular neurons have reduced amplitudes with no change in membrane potential, input resistance and presynaptic fiber volleys. These results suggest that activation of 5-HT1B receptors reduces the release of glutamate from incoming fibers originating from CA1 pyramidal cells. In presence of 5-HT (10 microM), theta patterned stimulation still induced LTP, similar to that observed in control slices. Application of similar concentrations of 5-HT during double pulse stimulation (interval 10-15 ms) reduced the response to the first pulse (repetition interval 30 s), but the response to the second pulse of the pair was unaffected. We propose that 5-HT1B receptor activity suppresses subicular transmission at low but not at high frequencies.
Boeijinga
P H
PH
CNS Department, Preclinical Research, Sandoz Pharma Ltd., Basle, Switzerland.
Boddeke
H W
HW
D000161:Acoustic Stimulation; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000502:physiology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects*
D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D018698:Glutamic Acid