Neuroscience 2000 Abstract
| Presentation Number: | 136.1 |
|---|---|
| Abstract Title: | Voltage-gated sodium channels and glutamate release underlie bold functional MRI response to forepaw stimulation in the rat. |
| Authors: |
Kida, I.*1
; Hyder, F.2
; Novotny, E. J.1,3
; Abi-Saab, W.4
; Behar, K. L.1
1Neurology, Yale University, New Haven, CT 2Diagnostic Radiology, Yale University, New Haven, CT 3Pediatrics, Yale University, New Haven, CT 4Psychiatry, Yale University, New Haven, CT |
| Primary Theme and Topics |
D. Neurotransmitters, Modulators, Transporters, and Receptors - 42. Excitatory amino acids |
| Secondary Theme and Topics | C. Excitable Membranes and Synaptic Transmission<br />- 35. Sodium channels |
| Session: |
136. Excitatory amino acids III Poster |
| Presentation Time: | Sunday, November 5, 2000 1:00 PM-2:00 PM |
| Location: | Hall G-J |
| Keywords: | MAGNETIC RESONANCE IMAGING, SOMATOSENSORY CORTEX, NEUROMODULATION, PHARMACODYNAMICS |
We tested the hypothesis that activation of voltage-gated Na+ channels and glutamate (GLU) release underlies functional magnetic resonance imaging (fMRI) signal based on the blood oxygenation level dependent (BOLD) during somatosensory activation. The BOLD fMRI experiments were performed at 7 Tesla on α-chloralose anesthetized rats undergoing forepaw stimulation before and for successive times after the application of lamotrigine (LTG), which is a neuronal voltage-gated Na+ channel blocker and GLU release inhibitor. LTG led to a time-dependent attenuation of the BOLD fMRI signal increase in somatosensory cortex during forepaw stimulation of 72% between 60-90 min after administration. BOLD signal during forepaw stimulation declined significantly from 7.2±1.0% before LTG to 2.0±2.3% (P<0.0016), while the volume of the activated region declined from 5.9±0.9 mm3 to 0.9±1.0 mm3 (P<0.0001). These results strongly suggest that voltage-gated Na+ channels and GLU release are involved in the BOLD fMRI response during somatosensory activation of the rat cortex. These results also support recent NMR studies (Sibson et al, PNAS 95:316,1998; Rothman et al, Phil. Trans R Soc Lond 354:1165,1999) showing that the glutamate/glutamine (GLU/GLN) cycle between neurons and astrocytes constitutes a major metabolic flux and is linearly related to cortical oxidative metabolism over a wide activity range. Together these findings support the hypothesis that the GLU/GLN cycle underlies the functional imaging signal during cortical activation.
Supported by NIH grants, HD-32573 & NS-34813 (KLB), NS-37203 (FH), and NSF grant, DBI-9730892 (FH).
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2000 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2000. Online.
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