Voltage-gated calcium channels play crucial roles in the glutamate-induced phase shifts of the rat suprachiasmatic circadian clock
- Authors
- Kim, DY; Choi, HJ; Kim, JS; Kim, YS; Jeong, DU; Shin, HC; Kim, MJ; Han, HC; Hong, SK; Kim, YI
- Issue Date
- Mar-2005
- Publisher
- WILEY
- Keywords
- electrophysiology; photic resetting; retinohypothalamic tract; SCN
- Citation
- EUROPEAN JOURNAL OF NEUROSCIENCE, v.21, no.5, pp.1215 - 1222
- Indexed
- SCIE
SCOPUS
- Journal Title
- EUROPEAN JOURNAL OF NEUROSCIENCE
- Volume
- 21
- Number
- 5
- Start Page
- 1215
- End Page
- 1222
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/123252
- DOI
- 10.1111/j.1460-9568.2005.03950.x
- ISSN
- 0953-816X
- Abstract
- The resetting of the circadian clock based on photic cues delivered by the glutamatergic retinohypothalamic tract is an important process helping mammals to function adaptively to the daily light-dark cycle. To see if the photic resetting relies on voltage-gated Ca2+ channels (VGCCs), we examined the effects of VGCC blockers on the glutamate-induced phase shifts of circadian firing activity rhythms of suprachiasmatic nucleus (SCN) neurons in hypothalamic slices. First, we found that a cocktail of amiloride, nimodipine and omega-conotoxin MVIIC (T-, L- and NPQ-type VGCC antagonists, respectively) completely blocked both phase delays and advances, which were, respectively, induced by glutamate application in early and late night. Next, we discovered that: (i) amiloride and another T-type VGCC antagonist, mibefradil, completely obstructed the delays without affecting the advances; (ii) nimodipine completely blocked the advances while having less impact on delays; and (iii) omega-conotoxin MVIIC blocked largely, if not entirely, both delays and advances. Subsequent whole-cell recordings revealed that T-type Ca2+ currents in neurons in the ventrolateral, not dorsomedial, region of the SCN were larger during early than late night, whereas L-type Ca2+ currents did not differ from early to late night in both regions. These results indicate that VGCCs play important roles in glutamate-induced phase shifts, T-type being more important for phase delays and L-type being so for phase advances. Moreover, the results point to the possibility that a nocturnal modulation of T-type Ca2+ current in retinorecipient neurons is related to the differential involvement of T-type VGCC in phase delays and advances.
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Collections - Graduate School > Department of Biomedical Sciences > 1. Journal Articles
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