title: Melatonin stimulates dendrite formation and complexity in the hilar zone of the rat hippocampus: participation of the Ca++/Calmodulin complex.
abstract: Melatonin (MEL), the main product synthesized by the pineal gland, stimulates early and late stages of neurodevelopment in the adult brain. MEL increases dendrite length, thickness and complexity in the hilar and mossy neurons of hippocampus. Dendrite formation involves activation of Ca2+/Calmodulin (CaM)-dependent kinase II (CaMKII) by CaM. Previous work showed that MEL increased the synthesis and translocation of CaM, suggesting that MEL activates CaM-dependent enzymes by this pathway. In this work we investigated whether MEL stimulates dendrite formation by CaMKII activation in organotypic cultures from adult rat hippocampus. We found that the CaMKII inhibitor, KN-62, abolished the MEL stimulatory effects on dendritogenesis and that MEL increased the relative amount of CaM in the soluble fraction of hippocampal slices. Also, PKC inhibition abolished dendritogenesis, while luzindole, an antagonist of MEL receptors (MT1/2), partially blocked the effects of MEL. Moreover, autophosphorylation of CaMKII and PKC was increased in presence of MEL, as well as phosphorylation of ERK1/2. Our results indicate that MEL stimulates dendrite formation through CaMKII and the translocation of CaM to the soluble fraction. Dendritogenesis elicited by MEL also required PKC activation, and signaling through MT1/2 receptors was partially involved. Data strongly suggest that MEL could repair the loss of hippocampal dendrites that occur in neuropsychiatric disorders by increasing CaM levels and activation of CaMKII.
authors.affiliation: Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco No. 101, Col. San Lorenzo-Huipulco, CP 14370 Tlalpan, DF, Mexico. aline.dmgzalonso@gmail.com.
authors.forename: Aline
authors.initials: A
authors.lastname: Domínguez-Alonso
authors.affiliation: Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco No. 101, Col. San Lorenzo-Huipulco, CP 14370 Tlalpan, DF, Mexico. mvaldes@imp.edu.mx.
authors.forename: Marcela
authors.initials: M
authors.lastname: Valdés-Tovar
authors.affiliation: Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco No. 101, Col. San Lorenzo-Huipulco, CP 14370 Tlalpan, DF, Mexico. hecsolch@imp.edu.mx.
authors.forename: Héctor
authors.initials: H
authors.lastname: Solís-Chagoyán
authors.affiliation: Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calzada México-Xochimilco No. 101, Col. San Lorenzo-Huipulco, CP 14370 Tlalpan, DF, Mexico. bekin@imp.edu.mx.
authors.forename: Gloria
authors.initials: G
authors.lastname: Benítez-King
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D055495:Neurogenesis / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D017208:Rats, Wistar; D044094:Receptors, Melatonin / Q000378:metabolism; D014363:Tryptamines / Q000494:pharmacology
chemical_list: D002147:Calmodulin; D044094:Receptors, Melatonin; D014363:Tryptamines; C057154:luzindole; D011493:Protein Kinase C; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D008550:Melatonin; D002118:Calcium