title: Single- and double-label immunocytochemical study of the ovine suprachiasmatic nucleus (SCN): GABAergic and peptidergic relationships.
abstract: This study evaluated the neuropeptide and neurotransmitter content of the ovine suprachiasmatic nucleus (SCN) using both single- and double-label immunocytochemical methods. Single-label immunocytochemistry identified a few lightly labeled gamma aminobutyric acid (GABA) cells within the SCN as well as a dense plexus of fibers staining positive for the GABA biosynthetic enzyme, glutamic acid decarboxylase (GAD). Vasoactive intestinal polypeptide (VIP) fibers exhibited a similar distribution to GAD fibers; VIP cells were found throughout the SCN, as well as in the paraventricular (PVN) and supraoptic nuclei. Both GAD and VIP fibers exited dorsally from the SCN towards the PVN. Neurophysin (NP) and neuropeptide-Y (NPY) fibers were sparsely distributed throughout the SCN. Double-label immunocytochemistry revealed that GAD varicosities were often in close apposition to VIP cells. These results confirm the presence of GABAergic elements within the sheep SCN. Furthermore, they raise the possibility of a GABAergic modulation of VIP neuronal activity within the ovine SCN.
authors.affiliation: Department of Anatomy and Cell Biology, University of Cincinnati College of Medicine, OH 45267-0521.
authors.forename: H T
authors.initials: HT
authors.lastname: Jansen
authors.forename: Q
authors.initials: Q
authors.lastname: Gong
authors.forename: R B
authors.initials: RB
authors.lastname: Norgren
authors.forename: M N
authors.initials: MN
authors.lastname: Lehman
mesh_terms: D000818:Animals; D005260:Female; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D009412:Nerve Fibers / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D009478:Neuropeptide Y / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism*; D009481:Neurophysins / Q000378:metabolism; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D009478:Neuropeptide Y; D009479:Neuropeptides; D009481:Neurophysins; D014660:Vasoactive Intestinal Peptide; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase