Distinct localization of prokineticin 2 and prokineticin receptor 2 mRNAs in the rat suprachiasmatic nucleus.
The suprachiasmatic nucleus (SCN) is the master circadian clock that regulates physiological and behavioral circadian rhythms in mammals. Prokineticin 2 (PK2) is highly expressed in the SCN, and its involvement in the generation of circadian locomotor activity has been reported previously. In the present study, using in situ hybridization methods, we investigated the localization of PK2 and prokineticin receptor 2 (PKR2), a specific receptor for PK2, in the rat SCN. In steady light : dark (L : D = 12 : 12 h) and constant dark conditions, rPK2 mRNA displayed a robust circadian oscillation with a peak occurring during the day. Moreover, during peak expression, the rPK2 mRNA-positive neurons were scattered in both the dorsomedial and ventrolateral SCN, which are two functionally and morphologically distinct subregions. Furthermore, double-labeling in situ hybridization experiments revealed that greater than 50% of the rPK2 mRNA-containing neurons co-expressed either vasoactive intestinal peptide (VIP), gastrin-releasing peptide (GRP) or arginine vasopressin (AVP) in the SCN. In contrast, the rPKR2 mRNA levels did not show significant diurnal alterations. rPKR2 mRNA-containing neurons were also clustered in the dorsolateral part of the SCN, which shows negligible labeling of either rAVP, rVIP, rGRP or rPK2 transcripts. In addition, this region exhibited a delayed cycling of the rPer1 gene. These results suggest an intrinsic PK2 neurotransmission and functionally distinct roles for PKR2-expressing neurons in the SCN.
Masumoto
Koh-hei
KH
Department of Physics, Informatics and Biology, Yamaguchi University, Yoshida, Yamaguchi 753-8512, Japan.
Nagano
Mamoru
M
Takashima
Naoyuki
N
Hayasaka
Naoto
N
Hiyama
Hideki
H
Matsumoto
Shun-ichiro
S
Inouye
Shin-Ichi T
ST
Shigeyoshi
Yasufumi
Y
D000818:Animals; D001127:Arginine Vasopressin / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology; D019886:Gastrin-Releasing Peptide / Q000235:genetics / Q000378:metabolism; D005768:Gastrointestinal Hormones / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D017403:In Situ Hybridization / Q000379:methods; D008297:Male; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D018000:Receptors, Peptide / Q000235:genetics / Q000378:metabolism*; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000235:genetics / Q000378:metabolism
D005768:Gastrointestinal Hormones; D009479:Neuropeptides; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; C513686:prokineticin 2, rat; C513688:prokineticin receptor 2, rat; D001127:Arginine Vasopressin; D014660:Vasoactive Intestinal Peptide; D019886:Gastrin-Releasing Peptide