Circadian changes in PACAP type 1 (PAC1) receptor mRNA in the rat suprachiasmatic and supraoptic nuclei.
A receptor for pituitary adenylate cyclase activating polypeptide (PACAP), denoted as PAC1, is expressed in the suprachiasmatic nuclei (SCN). Since the circadian clock demonstrates phase-dependent sensitivity to PACAP, we have used in situ hybridization histochemistry to examine whether PAC1 mRNA is differentially expressed in the rat SCN across the 24-h cycle. There was a significant variation in PAC1 mRNA within the SCN and supraoptic nuclei during the light-dark cycle and in constant darkness, with peaks at the middle of both the real and subjective day and night; no significant variation was observed in the cingulate cortex. The results suggest that the phase-dependent actions of PACAP on the clock may involve phase-specific changes in the availability of PAC1 receptors within the SCN.
Cagampang
F R
FR
Anatomy and Human Biology, Division of Biomedical Sciences, King's College London, London WC2R 2LS, UK.
Piggins
H D
HD
Sheward
W J
WJ
Harmar
A J
AJ
Coen
C W
CW
D000704:Analysis of Variance; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D006651:Histocytochemistry; D017403:In Situ Hybridization; D008297:Male; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone / Q000235:genetics*; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*; D013495:Supraoptic Nucleus / Q000378:metabolism*
C495505:Adcyap1r1 protein, rat; D012333:RNA, Messenger; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone