ABSTRACT
Pituitary adenylate cyclase activating polypeptide (PACAP) is a pleiotropic neuropeptide with widespread distribution. It plays pivotal role in neuronal development. PACAP-immunoreactive fibers have been found in the tooth pulp, and recently, it has been shown that PACAP may also play a role in the regeneration of the periodontium after luxation injuries. However, there is no data about the effect of endogenous PACAP on tooth development. Ectodermal organogenesis including tooth development is regulated by different members of bone morphogenetic protein (BMP), fibroblast growth factor (FGF), hedgehog (HH), and Wnt families. There is also a growing evidence to support the hypothesis that PACAP interacts with sonic hedgehog (SHH) receptor (PTCH1) and its downstream target (Gli1) suggesting its role in tooth development. Therefore, our aim was to study molar tooth development in mice lacking endogenous PACAP. In this study morphometric, immunohistochemical and structural comparison of molar teeth in pre-eruptive developmental stage was performed on histological sections of 7-day-old wild-type and PACAP-deficient mice. Further structural analysis was carried out with Raman microscope. The morphometric comparison of the 7-day-old samples revealed that the dentin was significantly thinner in the molars of PACAP-deficient mice compared to wild-type animals. Raman spectra of the enamel in wild-type mice demonstrated higher diversity in secondary structure of enamel proteins. In the dentin of PACAP-deficient mice higher intracrystalline disordering in the hydroxyapatite molecular structure was found. We also obtained altered SHH, PTCH1 and Gli1 expression level in secretory ameloblasts of PACAP-deficient mice compared to wild-type littermates suggesting that PACAP might play an important role in molar tooth development and matrix mineralization involving influence on SHH signaling cascade.
Subject(s)
Molar/metabolism , Pituitary Adenylate Cyclase-Activating Polypeptide/deficiency , Ameloblasts/metabolism , Animals , Dental Enamel/growth & development , Dental Enamel/metabolism , Dentin/growth & development , Dentin/metabolism , Durapatite/metabolism , Hedgehog Proteins/genetics , Hedgehog Proteins/metabolism , Kruppel-Like Transcription Factors/genetics , Kruppel-Like Transcription Factors/metabolism , Mice , Molar/anatomy & histology , Molar/growth & development , Patched Receptors , Patched-1 Receptor , Pituitary Adenylate Cyclase-Activating Polypeptide/genetics , Pituitary Adenylate Cyclase-Activating Polypeptide/metabolism , Receptors, Cell Surface/genetics , Receptors, Cell Surface/metabolism , Zinc Finger Protein GLI1ABSTRACT
The effects of different environmental factors on the circadian rhythm of melatonin release by chicken pineal glands were analyzed in 5-day experiments in vitro. Periodic, brief 4-h illumination at around midnight resulted in phase inversion in 2 days. Exposure to repeated 41 degrees C temperature elevation at around midnight caused no phase shift in the basic melatonin rhythm. Repeated inversion of the polarity of the magnetic field also affected rhythmic melatonin release. Additionally, expressions of Per1, Per2, Per3, Bmal1, Bmal2, Clock, Cry1, and Cry2 clock genes were simultaneously detected in single chicken pineal glands.
