TY - JOUR
T1 - Expression of orexin-A and orexin receptors in the kidney and the presence of orexin-A-like immunoreactivity in human urine
AU - Takahashi, Kazuhiro
AU - Arihara, Zenei
AU - Suzuki, Takashi
AU - Sone, Masahiko
AU - Kikuchi, Kumi
AU - Sasano, Hironobu
AU - Murakami, Osamu
AU - Totsune, Kazuhito
N1 - Funding Information:
This work was supported in part by a Grant-in-Aid for Scientific Research (C) from the Ministry of Education, Science, Sports and Culture of Japan, by a Research Grant from the HIROMI Medical Research Foundation (2001) and by a Research Grant from the Intelligent Cosmos (2002, 2003).
PY - 2006/4
Y1 - 2006/4
N2 - Orexin-A (hypocretin-1), a neuropeptide with stimulatory actions on arousal and appetite, was originally shown to be specifically expressed in the hypothalamus. We studied expression of orexin-A and orexin receptors in the kidney and the presence of orexin-A-like immunoreactivity in human urine. Immunocytochemistry showed that orexin-A-like immunoreactivity and two types of orexin receptors (types 1 and 2) were localized in the tubules of the human kidney obtained at autopsy. Orexin-A-like immunoreactivity was detected in human kidneys (21.3 ± 6.2 fmol/g wet weight, mean ± S.E.M., n = 4) and rat kidneys (16.2 ± 1.6 fmol/g wet weight, n = 5) by radioimmunoassay, although the levels were much lower than the levels in the brain. Orexin-A-like immunoreactivity was present in the urine obtained from male healthy volunteers (67.8 ± 4.5 pmol/l, n = 5). Reverse phase high-performance liquid chromatography showed that most of orexin-A-like immunoreactivity of the urine extract was eluted earlier than authentic orexin-A, suggesting that orexin-A-like immunoreactivity in urine was modified to hydrophilic forms. Reverse transcriptase polymerase chain reaction showed expression of orexin receptors 1 and 2 mRNAs in the human kidney. These findings suggest that orexin-A is produced by the renal tubular cells and secreted into urine. Orexin-A may act on the kidney in the autocrine or paracrine fashion, or via the urine (urocrine fashion).
AB - Orexin-A (hypocretin-1), a neuropeptide with stimulatory actions on arousal and appetite, was originally shown to be specifically expressed in the hypothalamus. We studied expression of orexin-A and orexin receptors in the kidney and the presence of orexin-A-like immunoreactivity in human urine. Immunocytochemistry showed that orexin-A-like immunoreactivity and two types of orexin receptors (types 1 and 2) were localized in the tubules of the human kidney obtained at autopsy. Orexin-A-like immunoreactivity was detected in human kidneys (21.3 ± 6.2 fmol/g wet weight, mean ± S.E.M., n = 4) and rat kidneys (16.2 ± 1.6 fmol/g wet weight, n = 5) by radioimmunoassay, although the levels were much lower than the levels in the brain. Orexin-A-like immunoreactivity was present in the urine obtained from male healthy volunteers (67.8 ± 4.5 pmol/l, n = 5). Reverse phase high-performance liquid chromatography showed that most of orexin-A-like immunoreactivity of the urine extract was eluted earlier than authentic orexin-A, suggesting that orexin-A-like immunoreactivity in urine was modified to hydrophilic forms. Reverse transcriptase polymerase chain reaction showed expression of orexin receptors 1 and 2 mRNAs in the human kidney. These findings suggest that orexin-A is produced by the renal tubular cells and secreted into urine. Orexin-A may act on the kidney in the autocrine or paracrine fashion, or via the urine (urocrine fashion).
KW - Hypocretin
KW - Kidney
KW - Orexin
KW - Urine
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U2 - 10.1016/j.peptides.2005.08.008
DO - 10.1016/j.peptides.2005.08.008
M3 - Article
C2 - 16202475
AN - SCOPUS:33645391991
VL - 27
SP - 871
EP - 877
JO - Peptides
JF - Peptides
SN - 0196-9781
IS - 4
ER -