Per2 gene expressions in the suprachiasmatic nucleus and liver differentially respond to nutrition factors in rats.
BACKGROUND
We previously reported that parenteral nutrition (PN) altered the circadian rhythm of clock gene expression in the suprachiasmatic nucleus (SCN) and liver of rats. The present study was designed to investigate what factor(s) in the PN solution causes the alteration.


METHODS
Male Wistar rats, kept under light and dark conditions, were divided into 4 groups after cannulation. The sham operation group received saline solution from 8 am to 8 pm at the rate of 36 mL/kg/12 hours. The glucose, amino acid, and saline groups received a glucose solution (20% wt/vol glucose, 261 kcal/kg/d, Na(+) 50 meq/L and Cl(-) 50 meq/L), an amino acid solution (4.3% wt/vol 1.78 gN/kg/d, Na +50 meq/L and Cl(-) 50 meq/L) and a saline solution from 8 am to 8 pm at a rate of 240 mL/kg/12 hours, respectively. Rats were killed every 4 hours (9 am = Zeitgeber Time (ZT) 02, 1 pm = ZT06, 5 pm = ZT10, 9 pm = ZT14, 1 am = ZT18, 5 am = ZT22, n = 3 at each point), and brain and liver samples were removed. rPer2 expression in the SCN and liver was analyzed by in situ hybridization and Northern blotting, respectively.


RESULTS
Compared with the sham-operation rats, the peak time of rPer2 expression in the SCN was significantly affected by glucose, amino acid, and saline solutions. Among them, glucose-group rats showed the rPer2 expression most similar to that of diurnal PN. On the other hand, the rPer2 expression in the liver was shifted in the glucose and amino-acid-solution groups. The pattern of rPer2 expressions in the amino acid group was most similar to that of the diurnal PN group.


CONCLUSIONS
These results indicate that the most potent entrainer for the SCN clock is glucose, whereas that for the liver is amino acid.
Iwanaga
Hiroshi
H
Department of Surgery and Clinical Oncology, Osaka University Graduate School of Medicine 2-2-E2, Yamada-Oka, Suita, Osaka 565-0871, Japan.
Yano
Masahiko
M
Miki
Hirofumi
H
Okada
Kazuyuki
K
Azama
Takashi
T
Takiguchi
Syuji
S
Fujiwara
Yoshiyuki
Y
Yasuda
Takushi
T
Nakayama
Mitsuo
M
Kobayashi
Masaru
M
Oishi
Katsutaka
K
Ishida
Norio
N
Nagai
Katsuya
K
Monden
Morito
M
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D018797:Cell Cycle Proteins; D002940:Circadian Rhythm; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism; D017403:In Situ Hybridization; D008099:Liver / Q000378:metabolism* / Q000502:physiology; D008297:Male; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D010288:Parenteral Nutrition; D056950:Period Circadian Proteins; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013493:Suprachiasmatic Nucleus / Q000378:metabolism* / Q000502:physiology; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
D000596:Amino Acids; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; C513311:Per2 protein, rat; D056950:Period Circadian Proteins; D014157:Transcription Factors; D005947:Glucose