Interaction of colocalized neuropeptides: functional significance in the circadian timing system

• Published in: The Journal of neuroscience 1991-03, Vol.11 (3), p.846-851
• Main Authors: Albers, HE, Liou, SY, Stopa, EG, Zoeller, RT
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Biological and medical sciences; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Circadian Rhythm; Fundamental and applied biological sciences. Psychology; Gastrin-Releasing Peptide; Gastrointestinal Hormones - physiology; Hypothalamus - drug effects; Hypothalamus - physiology; In Vitro Techniques; Male; Molecular Sequence Data; Neurons - drug effects; Neurons - physiology; Oligonucleotide Probes; Peptide PHI - genetics; Peptide PHI - pharmacology; Peptide PHI - physiology; Peptides - genetics; Peptides - pharmacology; Peptides - physiology; Rats; Signal Transduction - drug effects; Suprachiasmatic Nucleus - drug effects; Suprachiasmatic Nucleus - physiology; Vasoactive Intestinal Peptide - genetics; Vasoactive Intestinal Peptide - pharmacology; Vasoactive Intestinal Peptide - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/JNEUROSCI.11-03-00846.1991

The suprachiasmatic nucleus (SCN), which appears to act as a circadian clock, contains a subpopulation of local circuit neurons in which vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI), and gastrin releasing peptide (GRP) are colocalized. To determine whether VIP, PHI, and GRP interact within the SCN to produce a signal important for circadian control, the behavioral and cellular effects of coadministration of these neuropeptides were investigated. Coadministration of VIP, PHI, and GRP within the SCN mimicked the phase-delaying effects of light on circadian control following in vivo microinjection and activated SCN single units recorded in vitro. These behavioral and cellular effects of coadministration of VIP, PHI, and GRP were significantly greater than administration of VIP, PHI, or GRP alone or coadministration of any 2 of these peptides. These data illustrate a new mechanism whereby multiple, colocalized neuropeptides interact in a functionally significant manner, and indicate that the interaction of VIP, PHI, and GRP may be involved in the regulation of circadian rhythms by the SCN.