title: Rhythms of glutamic acid decarboxylase mRNA in the suprachiasmatic nucleus.
abstract: The purpose of the present study was to determine whether there is a rhythm in glutamic acid decarboxylase (GAD) message in the suprachiasmatic nucleus (SCN) of rats housed in a light:dark cycle. The mRNAs encoding two isoforms of GAD (i.e., GAD65 and GAD67) were examined using in situ hybridization histochemistry. Computerized image analysis of film autoradiographs revealed that GAD65 mRNA was significantly higher in the light than it was in the dark. GAD67 mRNA levels were lower overall and did not decrease significantly in the dark. Following emulsion autoradiography, silver grain counts over individual SCN cells indicated that GAD65 mRNA was highest in the dorsomedial hypothalamus during the light. These data suggest that GAD mRNA varies rhythmically in the SCN and that mRNA levels are regulated differently within SCN subdivisions during the light:dark cycle.
authors.affiliation: Department of Biology, Georgia State University, Atlanta 30303, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Huhman
authors.forename: A C
authors.initials: AC
authors.lastname: Hennessey
authors.forename: H E
authors.initials: HE
authors.lastname: Albers
mesh_terms: D000818:Animals; D001345:Autoradiography; D001483:Base Sequence; D002940:Circadian Rhythm; D003624:Darkness; D005968:Glutamate Decarboxylase / Q000096:biosynthesis*; D007527:Isoenzymes / Q000096:biosynthesis; D008027:Light; D008297:Male; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013462:Sulfur Radioisotopes; D013493:Suprachiasmatic Nucleus / Q000201:enzymology*; D014158:Transcription, Genetic
chemical_list: D007527:Isoenzymes; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D013462:Sulfur Radioisotopes; D005968:Glutamate Decarboxylase