Pituitary adenylate cyclase-activating polypeptide induces period1 and period2 gene expression in the rat suprachiasmatic nucleus during late night.
The suprachiasmatic nucleus generates circadian rhythms which are synchronized to the environmental light-dark cycle via the retinohypothalamic tract. Pituitary adenylate cyclase-activating polypeptide and glutamate, two neurotransmitters co-stored in the retinohypothalamic tract of the rat, are able to phase shift the endogenous rhythm similar to light. The "clock genes" period1 (per1) and per2, which show circadian oscillation within the suprachiasmatic nucleus, have been attributed a role in light-induced resetting of the mammalian circadian clock due to rapid induction of the period (per) genes after light stimulation at night. Using a rat in vitro brain slice model, we demonstrate by quantitative in situ hybridization histochemistry that the diurnal alteration in expression of both per genes in the suprachiasmatic nucleus was retained in vitro. In the model, we examined the effects of pituitary adenylate cyclase-activating polypeptide and glutamate alone and in combination on per1 and per2 gene expression at late subjective night (circadian time 19). Glutamate administration (10(-3)M) induced both per1 and per2 gene expression in the suprachiasmatic nucleus of the brain slice within 1h. The per gene responses were similar to the induction of gene expression observed after light stimulation in vivo at late night. Pituitary adenylate cyclase-activating polypeptide (10(-6)M) administered alone had no effect on the per gene expression, but when pituitary adenylate cyclase-activating polypeptide in micromolar concentration was applied before glutamate, the neuropeptide blocked the glutamate-induced per1 and per2 gene expression in the suprachiasmatic nucleus. In contrast to the lack of effect of pituitary adenylate cyclase-activating polypeptide itself in micromolar concentration, pituitary adenylate cyclase-activating polypeptide (10(-9)M) induced both per1 and per2 gene expression, an effect which was not augmented by co-application of glutamate. Our results provide the molecular substrate for the previous electrophysiological findings that pituitary adenylate cyclase-activating polypeptide in high concentration is able to block glutamate-induced phase advance at late night, and that the peptide in low concentration can induce a phase advance similar to light and glutamate.
Department of Clinical Biochemistry, Bispebjerg Hospital, University of Copenhagen, DK-2400 NV, Copenhagen, Denmark. hsn@biobase.dk
H S
HS
Nielsen
J
J
Hannibal
S M
SM
Knudsen
J
J
Fahrenkrug
D000818:Animals; D018797:Cell Cycle Proteins; D002940:Circadian Rhythm / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D018698:Glutamic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D009687:Nuclear Proteins / Q000235:genetics*; D056950:Period Circadian Proteins; D010775:Photic Stimulation; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000502:physiology*; D014157:Transcription Factors; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology
C495403:Adcyap1 protein, rat; D018797:Cell Cycle Proteins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009687:Nuclear Proteins; C539023:Per1 protein, mouse; C539024:Per1 protein, rat; C513312:Per2 protein, mouse; C513311:Per2 protein, rat; D056950:Period Circadian Proteins; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D012333:RNA, Messenger; D014157:Transcription Factors; D018698:Glutamic Acid