Hypothalamic growth hormone-releasing hormone mRNA varies across the day in rats.
Experiments were performed to determine whether growth hormone-releasing hormone (GHRH) mRNA displays diurnal variations in the hypothalamus and cortex of the rat. Levels of GHRH and beta-actin mRNA were measured from hypothalamic and cortical extracts using the reverse transcriptase polymerase chain reaction method in rats sacrificed at 4 h intervals across a 12:12 h light:dark cycle. Hypothalamic GHRH mRNA peaked around the light onset, declined during the light period, and stayed low in the dark. Variations in hypothalamic beta-actin and cortical GHRH mRNA levels were not observed. beta-Actin mRNA expression in the cortex was higher in the dark than in the light period. The results demonstrate that hypothalamic GHRH mRNA displays diurnal variations.
Bredow
S
S
Department of Physiology and Biophysics, University of Tennessee, Memphis 38163, USA.
Taishi
P
P
Obél
F
F
Guha-Thakurta
N
N
Krueger
J M
JM
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology*; D013007:Growth Hormone-Releasing Hormone / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley
D013007:Growth Hormone-Releasing Hormone