[Orexin A and neuropeptide Y levels in plasma and hypothalamus of rats with chronic renal failure].
OBJECTIVE
To explore the changes of orexin A and neuropeptide (NPY) in plasma and hypothalamus of rats with chronic renal failure (CRF).


METHODS
41 male Wister rats weighing 200 approximately 250 g were randomly divided into three groups: normal group, sham operation group, and CRF group (with the right kidney and 2/3 of the left kidney resected). A certain number of rats were decapitated 4, 8,and 12 weeks after respectively. Their hypothalami were removed and blood collected. Radioimmunoassay was used to measure the levels of orexin A and NPY in hypothalamus and plasma. Automatic biochemical analyzer was used to measure the serum creatinine.


RESULTS
The serum creatinine level of CRF rats was both significantly higher than those of the sham operation rats at week 8 and week 12, respectively. The plasma orexin A level of CRF rats at week 12 was 264 pg/ml +/- 62 pg/ml, significantly higher than that of sham operation group (183 pg/ml +/- 56pg/ml, P = 0.039). The hypothalamus orexin A level of CRF rats were 10.5 fmol/mg +/- 2.7 fmol/mg wet weight at week 12, significantly lower than that of sham operation rats (17.4 fmol/mg +/- 3.9 fmol/mg wet weight, P = 0.023). The plasma NPY levels of CRF rats at week 8 and week 12 were significantly higher than those of the sham operation rats (7.1 pmol/ml +/- 1.7 pmol/ml vs 5.0 pmol/ml +/- 0.5 pmol/ml, P = 0.01; and 7.9 pmol/ml +/- 1.1 pmol/ml vs 4.8 pmol/ml +/- 1.1 pmol/ml, P = 0.0008). The hypothalamus NPY level of CRF rats at week 12 were 70 fmol/mg +/- 23 fmol/mg wet weight, significantly lower than that of the sham operation rats (113 fmol/mg +/- 31 fmol/mg wet weight, P = 0.03).


CONCLUSIONS
Loss of renal function may diminish the excretion of orexin A and neuropeptide. The lowering of hypothalamus orexin A and neuropeptide Y levels may be one of the causes inducing anorexia in CRF.
Li
Jun-ling
JL
Department of Nephrology, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing 100730, China.
Zheng
Fa-lei
FL
Tan
Hui-bing
HB
Yin
Su-yan
SY
Yang
Ji-hong
JH
Li
Yan
Y
Bu
Yu-fen
YF
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis* / Q000097:blood; D007031:Hypothalamus / Q000737:chemistry*; D047908:Intracellular Signaling Peptides and Proteins; D007676:Kidney Failure, Chronic / Q000378:metabolism*; D008297:Male; D009478:Neuropeptide Y / Q000032:analysis* / Q000097:blood; D009479:Neuropeptides / Q000032:analysis* / Q000097:blood; D000068797:Orexins; D051381:Rats; D017208:Rats, Wistar
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009478:Neuropeptide Y; D009479:Neuropeptides; D000068797:Orexins