Summary
We have studied the effect of serotonin on synaptic transmission in rat hippocampal subiculum slices. Electrical stimulation of the alveus induced a field potential in the subiculum. The non-NMDA glutamate receptor antagonist, NBQX (3 × 10−6 mol/l) suppressed the response by 78%, indicating that the signal involves glutamatergic neurons. Application of serotonin suppressed (EC50 = 3.6 × 10−6 mol/l) the amplitude of he evoked potentials in a reversible, concentration-dependent manner. The responses to 5-HT were not altered after pretreatment with the 5-HT uptake blocker, fluvoxamine (10−5 mol/l) or a combination of the MAO inhibitor pargyline (10−5 mol/l) and ascorbic acid (10−4 mol/l). The responses to 5-HT were also unaffected by pretreatment with the 5-HT1A selective antagonist NAN-190 (10−6 mol/l), the 5-HT2A antagonist ketanserin (10−6 mol/l) or the 5-HT3/5-HT4 antagonist ICS 205–930 (10−6 mol/l).
The 5-HT1B selective agonist CP 93,129 mimicked the effects of serotonin, but was more potent (EC50 4.1 × 10−7 mol/l). The 5-HT1B receptor antagonist, (±)21-009 (3 × 10−7 mol/l), antagonized the response to 5-HT and CP 93,129 with a pKB value of 7.1 and 7.2, respectively. These results suggest that the effect of 5-HT in the rat subiculum is mediated by 5-HT1B receptors.
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Correspondence to: H.W.G.M. Boddeke at the above address
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Boeijinga, P.H., Boddeke, H.W.G.M. Serotonergic modulation of neurotransmission in the rat subicular cortex in vitro: a role for 5-HT1B receptors. Naunyn-Schmiedeberg's Arch Pharmacol 348, 553–557 (1993). https://doi.org/10.1007/BF00167229
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DOI: https://doi.org/10.1007/BF00167229