5-HT and GABA Modulate Intrinsic Excitability of Type I Interneurons in Hermissenda
| Autor: | Terry Crow, Nan Ge Jin, Lian-Ming Tian |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
Serotonin
Patch-Clamp Techniques genetic structures Physiology Biophysics Sensory system Inhibitory postsynaptic potential gamma-Aminobutyric acid Membrane Potentials Interneurons medicine Animals Patch clamp 5-HT receptor gamma-Aminobutyric Acid Membrane potential Chemistry General Neuroscience musculoskeletal neural and ocular physiology Hermissenda Excitatory Postsynaptic Potentials Articles Electric Stimulation Statocyst nervous system Inhibitory Postsynaptic Potentials Excitatory postsynaptic potential Neuroscience Photic Stimulation medicine.drug |
| Popis: | The sensory neurons (photoreceptors) in the visual system of Hermissenda are one site of plasticity produced by Pavlovian conditioning. A second site of plasticity produced by conditioning is the type I interneurons in the cerebropleural ganglia. Both photoreceptors and statocyst hair cells of the graviceptive system form monosynaptic connections with identified type I interneurons. Two proposed neurotransmitters in the graviceptive system, serotonin (5-HT) and γ-aminobutyric acid (GABA), have been shown to modify synaptic strength and intrinsic neuronal excitability in identified photoreceptors. However, the potential role of 5-HT and GABA in plasticity of type I interneurons has not been investigated. Here we show that 5-HT increased the peak amplitude of light-evoked complex excitatory postsynaptic potentials (EPSPs), enhanced intrinsic excitability, and increased spike activity of identified type Ie(A) interneurons. In contrast, 5-HT decreased spike activity and intrinsic excitability of type Ie(B) interneurons. The classification of two categories of type Ie interneurons was also supported by the observation that 5-HT produced opposite effects on whole cell steady-state outward currents in type Ie interneurons. Serotonin produced a reduction in the amplitude of light-evoked complex inhibitory PSPs (IPSPs), increased spontaneous spike activity, decreased intrinsic excitability, and depolarized the resting membrane potential of identified type Ii interneurons. In contrast to the effects of 5-HT, GABA produced inhibition in both types of Ie interneurons and type Ii interneurons. These results show that 5-HT and GABA can modulate the intrinsic excitability of type I interneurons independent of the presynaptic effects of the same transmitters on excitability and synaptic efficacy of photoreceptors. |
| Databáze: | OpenAIRE |
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