5-Hydroxytryptamine2 receptor facilitates GABAergic neurotransmission in rat hippocampus.
5-Hydroxytryptamine (5-HT; serotonin) administration enhances GABAergic synaptic activity recorded in pyramidal neurons of the CA1 region of hippocampus. Previous studies have attributed this effect to the activation of HT-5(3) receptors located on GABAergic interneurons. During unrelated experiments, we noticed that under our recording conditions, 5-HT can still increase GABAergic synaptic activity after the complete blockade of 5-HT3 receptors. This indicated the involvement of an additional 5-HT receptor subtype. Therefore, we reinvestigated the effects of 5-HT on GABAergic synaptic activity recorded in pyramidal cells of the CA1 region. The ability of 5-HT to increase GABAergic synaptic activity in the presence of 5-HT3 receptor blockade was mimicked by the selective 5-HT2 agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane and blocked by the selective 5-HT2 antagonist ketanserin. This indicated that the additional 5-HT receptor belongs to 5-HT2 receptor family. 5-HT2 receptor activation resulted in an increase in the frequency of spontaneous inhibitory postsynaptic currents as well as a shift in their amplitude distribution toward larger sizes. These effects were absent in the presence of tetrodotoxin. We interpret these results to indicate that 5-HT2 receptors activate GABAergic interneurons in the slice, leading to an increase in GABAergic synaptic activity onto pyramidal cells of the CA1 region.
Shen
R Y
RY
Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA.
Andrade
R
R
D000818:Animals; D006624:Hippocampus / Q000378:metabolism*; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D009435:Synaptic Transmission; D013779:Tetrodotoxin / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D011985:Receptors, Serotonin; D012701:Serotonin; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; D007650:Ketanserin