This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Gillespie, C. F. Articles by Albers, H. E. Search for Related Content PubMed PubMed Citation Articles by Gillespie, C. F. Articles by Albers, H. E. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB MUSCIMOL Social Bookmarking                         What's this?

Bicuculline Increases and Muscimol Reduces the Phase-Delaying Effects of Light and VIP/PHI/GRP in the Suprachiasmatic Region

Laboratory of Neuroendocrinology and Behavior, Departments of Biology and Psychology, Georgia State University, Atlanta, GA 30303

Kim L. Huhman

Laboratory of Neuroendocrinology and Behavior, Departments of Biology and Psychology, Georgia State University, Atlanta, GA 30303

Tokunbo O. Babagbemi

Laboratory of Neuroendocrinology and Behavior, Departments of Biology and Psychology, Georgia State University, Atlanta, GA 30303

H. Elliott Albers

Laboratory of Neuroendocrinology and Behavior, Departments of Biology and Psychology, Georgia State University, Atlanta, GA 30303

The present study investigated the effects of gamma-amino butyric acid (GABA)_A-active drugs on the ability of light or coadministration of vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI), and gastrin-releasing peptide (GRP) to phase delay hamster activity rhythms. Microinjection of the GABA_A agonist, muscimol, significantly (p < .01) reduced the phase-delaying effect of light administered at circadian time (CT) 13.5. By contrast, microinjection of the GABA_A antagonist, bicuculline, significantly (p < .01) increased the phase-delaying effect of light administered at CT 13.5. Microinjection of muscimol or bicuculline into the suprachiasmatic nucleus (SCN) produced little or no effect on circadian phase when no light pulses were provided. Coadministration of muscimol with VIP/PHI/GRP significantly (p < .01) reduced the phase-delaying effect of VIP/PHI/GRP, whereas administration of bicuculline with VIP/PHI/ GRP significantly (p <.05) increased the phase-delaying effect of these peptides. These data indicate that changes in GABA_A activity within the SCN can modulate the phase-delaying effects of light and VIP/PHI/GRP during the early portion of subjective night.

Key Words: circadian • GABA • GABAA • hamster • light • phase-shift • suprachiasmatic nucleus • vasoactive intestinal peptide • peptide histidine isoleucine • gastrin-releasing peptide

Journal of Biological Rhythms, Vol. 11, No. 2, 137-144 (1996)
DOI: 10.1177/074873049601100206


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				J. C. Ehlen and K. N. Paul Regulation of light's action in the mammalian circadian clock: role of the extrasynaptic GABAA receptor Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2009; 296(5): R1606 - R1612. [Abstract] [Full Text] [PDF]

				J. C. Ehlen, C. M. Novak, M. C. Karom, K. L. Gamble, and H. E. Albers Interactions of GABAA Receptor Activation and Light on Period mRNA Expression in the Suprachiasmatic Nucleus J Biol Rhythms, February 1, 2008; 23(1): 16 - 25. [Abstract] [PDF]

				L. L. Haak Metabotropic Glutamate Receptor Modulation of Glutamate Responses in the Suprachiasmatic Nucleus J Neurophysiol, March 1, 1999; 81(3): 1308 - 1317. [Abstract] [Full Text] [PDF]

				M. Tanaka, T. Matsuda, Y. Shigeyoshi, Y. Ibata, and H. Okamura Peptide Expression in GABAergic Neurons in Rat Suprachiasmatic Nucleus in Comparison with Other Forebrain Structures: A Double Labeling In Situ Hybridization Study J. Histochem. Cytochem., September 1, 1997; 45(9): 1231 - 1238. [Abstract] [Full Text] [PDF]

				L. Melo, D. A. Golombek, and M. R. Ralph Regulation of Circadian Photic Responses by Nitric Oxide J Biol Rhythms, August 1, 1997; 12(4): 319 - 326. [Abstract] [PDF]

				K. L. Huhman, A. C. Hennessey, and H. E. Albers Rhythms of Glutamic Acid Decarboxylase mRNA in the Suprachiasmatic Nucleus J Biol Rhythms, December 1, 1996; 11(4): 311 - 316. [Abstract] [PDF]