9-(tetrahydro-2-furyl)-adenine and thiazolyl-blue

Retaining or improving periodontal ligament (PDL) function is crucial for restoring periodontal defects. The aim of this study was to evaluate the physiological effects of low-power laser irradiation (LPLI) on the proliferation and osteogenic differentiation of human PDL (hPDL) cells. Cultured hPDL cells were irradiated (660 nm) daily with doses of 0, 1, 2 or 4 J⋅cm(-2). Cell proliferation was evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and the effect of LPLI on osteogenic differentiation was assessed by Alizarin Red S staining and alkaline phosphatase (ALP) activity. Additionally, osteogenic marker gene expression was confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR). Our data showed that LPLI at a dose of 2 J⋅cm(-2) significantly promoted hPDL cell proliferation at days 3 and 5. In addition, LPLI at energy doses of 2 and 4 J⋅cm(-2) showed potential osteogenic capacity, as it stimulated ALP activity, calcium deposition, and osteogenic gene expression. We also showed that cyclic adenosine monophosphate (cAMP) is a critical regulator of the LPLI-mediated effects on hPDL cells. This study shows that LPLI can promote the proliferation and osteogenic differentiation of hPDL cells. These results suggest the potential use of LPLI in clinical applications for periodontal tissue regeneration.

Topics: Adenine; Adenylyl Cyclase Inhibitors; Alkaline Phosphatase; Anthraquinones; Bone Morphogenetic Protein 2; Calcium; Cell Culture Techniques; Cell Differentiation; Cell Line; Cell Proliferation; Coloring Agents; Core Binding Factor Alpha 1 Subunit; Cyclic AMP; Gene Expression; Humans; L-Lactate Dehydrogenase; Lasers, Semiconductor; Low-Level Light Therapy; Osteocalcin; Osteogenesis; Periodontal Ligament; Radiation Dosage; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Tetrazolium Salts; Thiazoles

It is well established that cAMP counteracts myelin inhibition to permit axon regeneration in the central nervous system. On the other hand, the role of cAMP in axonal growth on permissive substrates remains controversial because the evidence available is contradictory. In view that elevation of cAMP represents an attractive therapeutic target to promote nerve regeneration in vivo, we investigated the effect of cAMP on neurite outgrowth and extension in motoneurons. We manipulated cAMP levels pharmacologically in cultured motoneurons and investigated targets downstream of cAMP of neurite outgrowth and extension on a permissive substrate. Reduction of cAMP by the adenylyl cyclase inhibitor SQ22536 inhibited, and elevation of cAMP by forskolin, dibutyryl cAMP, IBMX and rolipram increased outgrowth and extension of neurites. The cAMP-mediated effects occur via activation of protein kinase A (PKA) and were reduced by the inhibitors, H89 and Rp-cAMP. However, cAMP elevation did not lead to Erk activation that is an essential downstream component of neurotrophin signaling. These findings provide evidence for a key role of cAMP in promoting peripheral nerve regeneration after nerve injuries and indicate that this effect is unusual in not being mediated via Erk phosphorylation.

Topics: Adenine; Animals; Cell Survival; Cells, Cultured; Colforsin; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic CMP; Dose-Response Relationship, Drug; Embryo, Mammalian; Enzyme Activation; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Female; Motor Neurons; Neurites; Pregnancy; Rats; Rats, Sprague-Dawley; Spinal Cord; Tetrazolium Salts; Thiazoles