Format

Send to

Choose Destination
J Neurosci Methods. 2012 Jul 15;208(2):146-54. doi: 10.1016/j.jneumeth.2012.05.013. Epub 2012 May 22.

Cutaneous and electrically evoked glutamate signaling in the adult rat somatosensory system.

Author information

1
Spinal Cord and Brain Injury Research Center, College of Medicine, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA. smonif2@email.uky.edu

Abstract

Glutamate neurotransmission plays critical roles in normal central nervous system (CNS) function, neurodegenerative diseases, and neurotrauma. We determined whether glutamate signaling could be evoked within the anesthetized normal adult rat CNS with clinically relevant peripheral stimulation and recorded (at >1Hz) with glutamate-sensitive, ceramic microelectrode arrays (MEAs). Basal glutamate levels and both forelimb cutaneous and electrical stimulation-evoked glutamate release were measured within the cuneate nucleus, a relay of the mammalian dorsal columns somatosensory system. The MEAs with triangular, sharp-point tips were more effective at tissue penetration than the flat, blunt tips. Basal glutamate levels of 2.1±4.4μM (mean±SD, n=10 animals) were detected from 150μm to 1200μm below the brainstem dorsal surface. Cutaneous evoked glutamate signals showed an amplitude of 1.1±1.1μM and a duration of 7.3±6.5s (26 signals, n=6). Electrically evoked signals, like cutaneous ones, were both rapid and slowly rising. Electrically evoked signals, especially those evoked by stimulation trains, were more reproducible and had an amplitude of 1.2±1.4μM, duration of 19.4±17.3s, and latency from stimulus onset of 21.3±21.5s (25 signals, n=4). In contrast to cutaneous stimulation, glutamate signals evoked by electrical stimulation had longer durations and were recorded primarily in the middle and ventral cuneate nuclei. Importantly, both cutaneous and electrical stimulation of the contralateral forelimb and hindlimbs did not evoke glutamate signaling. With the use of MEAs, these results show, for the first time, somatosensory-pathway specific changes in glutamate levels during peripheral cutaneous and electrical stimulation.

PMID:
22627377
DOI:
10.1016/j.jneumeth.2012.05.013
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center