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- Title
Columnar distribution of activity dependent gabaergic depolarization in sensorimotor cortical neurons.
- Authors
Jaekwang Lee; Junsung Woo; Favorov, Oleg V.; Tommerdahl, Mark; Justin Lee, C.; Whitsel, Barry L.
- Abstract
Background: GABA, the major inhibitory neurotransmitter in CNS, has been demonstrated to paradoxically produce excitation even in mature brain. However activity-dependent form of GABA excitation in cortical neurons has not been observed. Here we report that after an intense electrical stimulation adult cortical neurons displayed a transient GABA excitation that lasted for about 30s.Results: Whole-cell patch recordings were performed to evaluate the effects of briefly applied GABA on pyramidal neurons in adult rodent sensorimotor cortical slice before and after 1 s, 20 Hz suprathreshold electrical stimulation of the junction between layer 6 and the underlying white matter (L6/WM stimulation). Immediately after L6/WM stimulation, GABA puffs produced neuronal depolarization in the center of the column-shaped region. However, both prior to or 30s after stimulation GABA puffs produced hyperpolarization of neurons. 2-photon imaging in neurons infected with adenovirus carrying a chloride sensor Clomeleon revealed that GABA induced depolarization is due to an increase in [Cl-]i after stimulation. To reveal the spatial extent of excitatory action of GABA, isoguvacine, a GABAA receptors agonist, was applied right after stimulation while monitoring the intracellular Ca2+ concentration in pyramidal neurons. Isoguvacine induced an increase in [Ca2+]i in pyramidal neurons especially in the center of the column but not in the peripheral regions of the column. The global pattern of the Ca2+ signal showed a column-shaped distribution along the stimulation site. Conclusion: These results demonstrate that the well-known inhibitory transmitter GABA rapidly switches from hyperpolarization to depolarization upon synaptic activity in adult somatosensory cortical neurons.
- Subjects
GABA; NEUROTRANSMITTERS; EXCITATION (Physiology); NEURONS; NEUROMUSCULAR depolarizing agents; ELECTRIC stimulation
- Publication
Molecular Brain, 2012, Vol 5, Issue 1, p33
- ISSN
1756-6606
- Publication type
Article
- DOI
10.1186/1756-6606-5-33