title: Influence of pinealectomy on levels of PACAP and cAMP in the chicken brain.
abstract: One of the recently found functions of pituitary adenylate cyclase activating polypeptide (PACAP) is the modulation of circadian rhythms. Widespread distribution of PACAP-containing neurons and receptors has been shown in the chicken. Recently, we have demonstrated that PACAP levels oscillate in a circadian manner in the chicken brain. Daily variation in PACAP levels might be influenced by several regulatory mechanisms. Among the structures that may regulate PACAP levels, one candidate is the pineal gland. Therefore, in the present study, we investigated the effect of pinealectomy on the levels of PACAP in the chicken brain. Animals were kept under 12:12-h light-dark schedule. Pinealectomy was performed at 3 weeks of age; sham-operated animals were used as controls. The animals were sacrificed at 15 and 24 h 1 week after pinealectomy. The brainstem and diencephalon were removed, and tissue samples were processed for PACAP and cAMP radioimmunoassay (RIA).PACAP and cAMP levels showed nighttime elevations in both the sham-operated and pinealectomized animals, except for the PACAP content in the diencephalon of pinealectomized chicken. PACAP levels of pinealectomized animals were significantly higher in the diencephalon and brainstem as compared to the control animals at both time-points. Levels of cAMP correlated well with levels of PACAP. The present results provide evidence that the pineal gland has an inhibitory impact on PACAP-neurons in the chicken brainstem and diencephalon.
authors.affiliation: Department of Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA. avigh@tulane.edu
authors.forename: Anikó
authors.initials: A
authors.lastname: Somogyvári-Vigh
authors.forename: Rita
authors.initials: R
authors.lastname: Józsa
authors.forename: Dóra
authors.initials: D
authors.lastname: Reglodi
authors.forename: Tibor
authors.initials: T
authors.lastname: Hollósy
authors.forename: Róbert
authors.initials: R
authors.lastname: Meggyesi
authors.forename: Istvan
authors.initials: I
authors.lastname: Lengvari
authors.forename: Akira
authors.initials: A
authors.lastname: Arimura
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002645:Chickens / Q000378:metabolism*; D002940:Circadian Rhythm; D000242:Cyclic AMP / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D010870:Pineal Gland / Q000601:surgery*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011863:Radioimmunoassay; D013997:Time Factors
chemical_list: D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D000242:Cyclic AMP