Neuroscience 2000 Abstract
| Presentation Number: | 835.4 |
|---|---|
| Abstract Title: | The inhibitory effect of high extracellular glucose on neurons in the ventromedial hypothalamic nucleus (VMN) is mediated by GABA. |
| Authors: |
Song, Z.*1
; Levin, B. E.2,3
; Tkacs, N. C.4
; Routh, V. H.1
1Pharm. & Physiol., NJ Med. Sch., Newark, NJ 2Neurosci., NJ Med. Sch., Newark, NJ 3Neurol. Serv., VAMC, E. Orange, NJ 4Sch. of Nursing, U. Penn., Philadelphia, PA |
| Primary Theme and Topics | I. Neural Basis of Behavior |
| Secondary Theme and Topics | E. Endocrine and Autonomic Regulation |
| Session: |
835. Limbic system and hypothalamus V Poster |
| Presentation Time: | Thursday, November 9, 2000 11:00 AM-12:00 PM |
| Location: | Hall G-J |
| Keywords: | glucose sensing, electrophysiology, KATP channel, brain slices |
We found previously that VMN glucosensing neurons are inhibited when extracellular glucose is either increased or decreased (Routh et al., SFN Abst. 25:416,99). The inhibitory effect of decreasing glucose was reversed by tolbutamide, suggesting the involvement of the ATP sensitive K+ (KATP) channel. This study was performed to determine the mechanism responsible for the inhibitory effect of high extracellular glucose. Slices 350 microns thick were sectioned through the VMN of brains of 14-21 d inbred diet-resistant (DR) Sprague-Dawley rats. Slices were then perfused with artificial CSF + 2.5 mM glucose. Current clamp recordings were made using conventional whole cell patch clamp with ATP (2 mM) in the patch pipette. Six of 42 VMN neurons hyperpolarized and decreased their action potential frequency when extracellular glucose was raised from 2.5 to 5 or 10 mM. Similarly, 8 of 52 VMN neurons hyperpolarized and decreased their action potential frequency when extracellular glucose was decreased from 2.5 to 0.1 mM. However, only 3 of 13 neurons were inhibited by both increasing and decreasing extracellular glucose. The inhibitory effect of high extracellular glucose was reversed by 10 μM bicuculline (n = 3). Interestingly, neurons which were inhibited by high glucose were also inhibited by 200 μM tolbutamide (n = 2). These data suggest that the inhibitory effect of high glucose is mediated by KATP channels on presynaptic GABAergic neurons.
Supported by ADA Career Dev. Award; RO1DK53181
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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