DTIC ADA219067: Neurochemical Control of Circadian Rhythms pdf

DTIC ADA219067: Neurochemical Control of Circadian Rhythms

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The suprachiasmatic nucleus (SCN), which appears to act as a circadian clock, contains a large subpopulation of local circuit neurons in which vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI) are co-localized. We are continuing to investigate the hypothesis that VIP/PHI- containing neurons are essential for the synchronization of circadian rhythms with the day-night cycle. Using in situ hybridization, we demonstrated that some, but not all SCN neurons that contain VIP/PHI mRNA also contain the mRNA encoding a third biologically active peptide, gastrin releasing peptide (GRP). Comparison of the cellular levels of VIP/PHI and GRP mRNA revealed that these MRNAs have distinctly different 24 hr patterns within the SCN. We also examined whether VIP, PHI and GRP interact within the SCN to produce a signal important for circadian control. Co-administration of VIP, PHI and GRP within the SCN in vivo mimicked the phase delaying effects of light on circadian control, and activated SCN single units recorded in vitro.

In contrast, administration of VIP, PHI or GRP alone, or co-administration of any two of these peptides did not produce the full behavioral or cellular response observed following co- administration of VIP, PHI and GRP. These data indicate that the interaction of VIP, PHI and GRP may be required for regulation of circadian rhythms by the SCN. Keywords: Peptides; Hypothalamus; Co-localization; Light; Gene expression

• Creator/s: Defense Technical Information Center
• Date: 2/20/1990
• Year: 1990
• Book Topics/Themes: DTIC Archive, Albers, H E, GEORGIA STATE UNIV ATLANTA, *NEUROCHEMISTRY, *LIGHT, *PEPTIDES, *CIRCADIAN RHYTHMS, IN VITRO ANALYSIS, PHASE, RELEASE, DELAY, DAY, NERVE CELLS, GENES, LEUCINE, BEHAVIOR, CIRCUITS, SYNCHRONISM, HYPOTHESES, RESPONSE(BIOLOGY), IN VIVO ANALYSIS, CELLS(BIOLOGY), RIBONUCLEIC ACIDS, INTESTINES, DIURNAL VARIATIONS, HISTIDINE, HYBRIDIZATION, CARDIOVASCULAR AGENTS, GASTRIN, HYPOTHALAMUS, CYCLES, POPULATION, INTERACTIONS, CONTROL, NIGHT

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