Neurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons.
We have previously described a population of 5-hydroxytryptamine neurons which repetitively fires bursts of usually two (but occasionally three or four) action potentials, with a short (<20 ms) interspike interval within a regular low-frequency firing pattern. Here we used a paradigm of elect...
| Main Authors: | , , , , , |
|---|---|
| Format: | Journal article |
| Language: | English |
| Published: |
2000
|
| _version_ | 1826259671221010432 |
|---|---|
| author | Gartside, SE Hajós-Korcsok, E Bagdy, E Hársing, L Sharp, T Hajós, M |
| author_facet | Gartside, SE Hajós-Korcsok, E Bagdy, E Hársing, L Sharp, T Hajós, M |
| author_sort | Gartside, SE |
| collection | OXFORD |
| description | We have previously described a population of 5-hydroxytryptamine neurons which repetitively fires bursts of usually two (but occasionally three or four) action potentials, with a short (<20 ms) interspike interval within a regular low-frequency firing pattern. Here we used a paradigm of electrical stimulation comprising twin pulses (with 7- or 10-ms inter-pulse intervals) to mimic this burst firing pattern, and compared the effects of single- and twin-pulse electrical stimulations in models of pre- and postsynaptic 5-hydroxytryptamine function. Firstly, we measured the effect of direct electrical stimulation (2 Hz for 2 min) of rat brain slices on efflux of preloaded [3H]5-hydroxytryptamine. In this in vitro model, twin-pulse stimulation increased the efflux of tritium by about twice as much as did single-pulse stimulation. This effect was evident in the medial prefrontal cortex (area under the curve: 2. 59+/-0.34 vs 1.28+/-0.22% relative fractional release), as well as in the caudate-putamen (3.93+/-0.65 vs 2.17+/-0.51%) and midbrain raphe nuclei (5.42+/-1.05 vs 2.51+/-0.75%). Secondly, we used in vivo microdialysis to monitor changes in endogenous extracellular 5-hydroxytryptamine in rat medial prefrontal cortex in response to electrical stimulation (3 Hz for 10 min) of the dorsal raphe nucleus. In this model, twin-pulse stimulation of the dorsal raphe nucleus increased 5-hydroxytryptamine by approximately twice as much as did single-pulse stimulation at the same frequency (area under the curve: 50.4+/-9.0 vs 24.2+/-4.4 fmol). Finally, we used in vivo extracellular recording to follow the response of postsynaptic neurons in the rat medial prefrontal cortex to 5-hydroxytryptamine released by dorsal raphe stimulation. Electrical stimulation of the dorsal raphe nucleus (1 Hz) induced a clear-cut poststimulus inhibition in the majority of cortical neurons tested. In these experiments, the duration of poststimulus inhibition following twin-pulse stimulation was markedly longer than that induced by single-pulse stimulation (200+/-21 vs 77+/-18.5 ms). Taken together, the present in vitro and in vivo data suggest that in 5-hydroxytryptamine neurons, short bursts of action potentials will propagate along the axon to the nerve terminal and will enhance both the release of 5-hydroxytryptamine and its postsynaptic effect. |
| first_indexed | 2024-03-06T18:53:30Z |
| format | Journal article |
| id | oxford-uuid:110a7689-4a6a-43ce-bd45-b341dab6add8 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T18:53:30Z |
| publishDate | 2000 |
| record_format | dspace |
| spelling | oxford-uuid:110a7689-4a6a-43ce-bd45-b341dab6add82022-03-26T09:59:57ZNeurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:110a7689-4a6a-43ce-bd45-b341dab6add8EnglishSymplectic Elements at Oxford2000Gartside, SEHajós-Korcsok, EBagdy, EHársing, LSharp, THajós, MWe have previously described a population of 5-hydroxytryptamine neurons which repetitively fires bursts of usually two (but occasionally three or four) action potentials, with a short (<20 ms) interspike interval within a regular low-frequency firing pattern. Here we used a paradigm of electrical stimulation comprising twin pulses (with 7- or 10-ms inter-pulse intervals) to mimic this burst firing pattern, and compared the effects of single- and twin-pulse electrical stimulations in models of pre- and postsynaptic 5-hydroxytryptamine function. Firstly, we measured the effect of direct electrical stimulation (2 Hz for 2 min) of rat brain slices on efflux of preloaded [3H]5-hydroxytryptamine. In this in vitro model, twin-pulse stimulation increased the efflux of tritium by about twice as much as did single-pulse stimulation. This effect was evident in the medial prefrontal cortex (area under the curve: 2. 59+/-0.34 vs 1.28+/-0.22% relative fractional release), as well as in the caudate-putamen (3.93+/-0.65 vs 2.17+/-0.51%) and midbrain raphe nuclei (5.42+/-1.05 vs 2.51+/-0.75%). Secondly, we used in vivo microdialysis to monitor changes in endogenous extracellular 5-hydroxytryptamine in rat medial prefrontal cortex in response to electrical stimulation (3 Hz for 10 min) of the dorsal raphe nucleus. In this model, twin-pulse stimulation of the dorsal raphe nucleus increased 5-hydroxytryptamine by approximately twice as much as did single-pulse stimulation at the same frequency (area under the curve: 50.4+/-9.0 vs 24.2+/-4.4 fmol). Finally, we used in vivo extracellular recording to follow the response of postsynaptic neurons in the rat medial prefrontal cortex to 5-hydroxytryptamine released by dorsal raphe stimulation. Electrical stimulation of the dorsal raphe nucleus (1 Hz) induced a clear-cut poststimulus inhibition in the majority of cortical neurons tested. In these experiments, the duration of poststimulus inhibition following twin-pulse stimulation was markedly longer than that induced by single-pulse stimulation (200+/-21 vs 77+/-18.5 ms). Taken together, the present in vitro and in vivo data suggest that in 5-hydroxytryptamine neurons, short bursts of action potentials will propagate along the axon to the nerve terminal and will enhance both the release of 5-hydroxytryptamine and its postsynaptic effect. |
| spellingShingle | Gartside, SE Hajós-Korcsok, E Bagdy, E Hársing, L Sharp, T Hajós, M Neurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons. |
| title | Neurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons. |
| title_full | Neurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons. |
| title_fullStr | Neurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons. |
| title_full_unstemmed | Neurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons. |
| title_short | Neurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons. |
| title_sort | neurochemical and electrophysiological studies on the functional significance of burst firing in serotonergic neurons |
| work_keys_str_mv | AT gartsidese neurochemicalandelectrophysiologicalstudiesonthefunctionalsignificanceofburstfiringinserotonergicneurons AT hajoskorcsoke neurochemicalandelectrophysiologicalstudiesonthefunctionalsignificanceofburstfiringinserotonergicneurons AT bagdye neurochemicalandelectrophysiologicalstudiesonthefunctionalsignificanceofburstfiringinserotonergicneurons AT harsingl neurochemicalandelectrophysiologicalstudiesonthefunctionalsignificanceofburstfiringinserotonergicneurons AT sharpt neurochemicalandelectrophysiologicalstudiesonthefunctionalsignificanceofburstfiringinserotonergicneurons AT hajosm neurochemicalandelectrophysiologicalstudiesonthefunctionalsignificanceofburstfiringinserotonergicneurons |