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Presynaptic modulation by somatostatin in the neostriatum
Violeta Gisselle Lopez-Huerta1, Fatuel Tecuapetla, Jaime N Guzman
1Departamento de Biofísica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, PO Box 70-253, Mexico City, DF, 04510, Mexico.
Neurochemical Research
|February 14, 2008
Summary
Somatostatin (SST) presynaptically regulates GABA release between medium spiny projection neurons (MSNs) in the neostriatum. This action, mediated by somatostatin receptors, fine-tunes motor control by modulating lateral inhibition within MSN networks.
Area of Science:
- Neuroscience
- Cellular Neuroscience
- Synaptic Plasticity
Background:
- Medium spiny projection neurons (MSNs) are the primary inhibitory, GABAergic neurons in the neostriatum.
- MSNs mediate lateral inhibition through local axon collaterals, crucial for selecting motor action circuits.
- MSNs also receive inhibitory input from local interneurons.
Purpose of the Study:
- To investigate the presynaptic role of somatostatin (SST) in regulating GABA release between MSNs.
- To determine if SST modulates inhibition originating from interneurons.
- To elucidate the mechanism and specificity of SST's action on MSN-MSN communication.
Main Methods:
- Paired pulse protocol to assess presynaptic release probability.
- Application of somatostatin (SST) and its antagonist, ciclosomatostatin (cicloSST).
- Electrophysiological recordings of MSN-MSN and MSN-interneuron synapses.
Main Results:
- Somatostatin (SST) was found to presynaptically inhibit GABA release from terminals connecting MSNs.
- This SST effect was reversible and not dependent on dopamine release.
- SST did not affect inhibitory transmission from local interneurons to MSNs.
- The SST action was specifically blocked by the somatostatin receptor antagonist, cicloSST.
Conclusions:
- A specific class of local interneuron releases SST to modulate MSN-MSN synaptic transmission.
- SST plays a critical role in regulating the strength of lateral inhibition within the neostriatum.
- This regulation by SST contributes to the precise selection of neuronal assemblies underlying motor actions.
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