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Melatonin stimulates dendrite formation and complexity in the hilar zone of the rat hippocampus: participation of the Ca++/Calmodulin complex.

Domínguez-Alonso A, Valdés-Tovar M, Solís-Chagoyán H, Benítez-King G - Int J Mol Sci (2015)

Bottom Line: 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.Our results indicate that MEL stimulates dendrite formation through CaMKII and the translocation of CaM to the soluble fraction.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.

View Article: PubMed Central - PubMed

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.

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.

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Related in: MedlinePlus

Schematic drawing of the modified Sholl method to determine the number and length of primary and secondary dendrites. A grid of concentric circles equidistantly drawn five micrometers apart was superimposed at the center of the neuronal soma (blue arrow). Dendrite formation was determined by counting the number of emerging dendrites from the soma. Primary dendrite length was measured from the soma up to the first intersection (green line). Complexity of dendrites was determined by counting the number of secondary dendrites as well as by measuring their length (red line).
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ijms-16-01907-f008: Schematic drawing of the modified Sholl method to determine the number and length of primary and secondary dendrites. A grid of concentric circles equidistantly drawn five micrometers apart was superimposed at the center of the neuronal soma (blue arrow). Dendrite formation was determined by counting the number of emerging dendrites from the soma. Primary dendrite length was measured from the soma up to the first intersection (green line). Complexity of dendrites was determined by counting the number of secondary dendrites as well as by measuring their length (red line).

Mentions: Dendrite parameters were evaluated in MAP2-stained hippocampal slices visualized with an optic microscope, and analyzed with the Sholl modified method [18,66]. Briefly, after neuron identification in the hilar zone of the dentate gyrus, concentric and equidistant circles (step size of 5 µm) were used as a template and drawn superimposed around the soma (Figure 8). Hilar neurons with a soma diameter of 10 µm were selected for analysis. A neuronal projection of at least 5 µm-length that was immunostained for MAP2 was considered as a primary dendrite. Total dendrite length was determined by measuring the distance between the soma and the more distant tip. Primary dendrite length was determined by measuring the distance between the soma and the first intersection. Secondary and tertiary dendrite length was determined by subtraction of the primary or secondary dendrite length from the total dendrite length. The number and length of primary, secondary and tertiary dendrites were determined from 5 neurons per field by quadruplicate (20 hilar neurons per group).


Melatonin stimulates dendrite formation and complexity in the hilar zone of the rat hippocampus: participation of the Ca++/Calmodulin complex.

Domínguez-Alonso A, Valdés-Tovar M, Solís-Chagoyán H, Benítez-King G - Int J Mol Sci (2015)

Schematic drawing of the modified Sholl method to determine the number and length of primary and secondary dendrites. A grid of concentric circles equidistantly drawn five micrometers apart was superimposed at the center of the neuronal soma (blue arrow). Dendrite formation was determined by counting the number of emerging dendrites from the soma. Primary dendrite length was measured from the soma up to the first intersection (green line). Complexity of dendrites was determined by counting the number of secondary dendrites as well as by measuring their length (red line).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4307341&req=5

ijms-16-01907-f008: Schematic drawing of the modified Sholl method to determine the number and length of primary and secondary dendrites. A grid of concentric circles equidistantly drawn five micrometers apart was superimposed at the center of the neuronal soma (blue arrow). Dendrite formation was determined by counting the number of emerging dendrites from the soma. Primary dendrite length was measured from the soma up to the first intersection (green line). Complexity of dendrites was determined by counting the number of secondary dendrites as well as by measuring their length (red line).
Mentions: Dendrite parameters were evaluated in MAP2-stained hippocampal slices visualized with an optic microscope, and analyzed with the Sholl modified method [18,66]. Briefly, after neuron identification in the hilar zone of the dentate gyrus, concentric and equidistant circles (step size of 5 µm) were used as a template and drawn superimposed around the soma (Figure 8). Hilar neurons with a soma diameter of 10 µm were selected for analysis. A neuronal projection of at least 5 µm-length that was immunostained for MAP2 was considered as a primary dendrite. Total dendrite length was determined by measuring the distance between the soma and the more distant tip. Primary dendrite length was determined by measuring the distance between the soma and the first intersection. Secondary and tertiary dendrite length was determined by subtraction of the primary or secondary dendrite length from the total dendrite length. The number and length of primary, secondary and tertiary dendrites were determined from 5 neurons per field by quadruplicate (20 hilar neurons per group).

Bottom Line: 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.Our results indicate that MEL stimulates dendrite formation through CaMKII and the translocation of CaM to the soluble fraction.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.

View Article: PubMed Central - PubMed

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.

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.

Show MeSH
Related in: MedlinePlus