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Diabetes induces early transient changes in the content of vesicular transporte...
Baptista, Filipa I.; Gaspar, Joana M.; Cristóvão, Armando; Santos, Paulo F.; Köfalvi, Attila; Ambrósio, António F.Diabetes induces changes in neurotransmitter release in central nervous system, which depend on the type of neurotransmitter and region studied. In this study, we evaluated the effect of diabetes (two and eight weeks duration) on basal and evoked release of [14C]glutamate and [3H]GABA in hippocampal and retinal synaptosomes. We also analyzed the effect of diabetes on the protein content of vesicular glutamate a...
Diabetes changes the levels of ionotropic glutamate receptors in the rat retina
Santiago, Ana R.; Gaspar, Joana M.; Baptista, Filipa I.; Cristóvão, Armando J.; Santos, Paulo F.; Kamphuis, Willem; Ambrósio, António F.Purpose: Diabetic retinopathy (DR) is a leading cause of vision loss and blindness among adults between the age 20 to 74. Changes in ionotropic glutamate receptor subunit composition can affect retinal glutamatergic neurotransmission and, therefore, contribute to visual impairment. The purpose of this study was to investigate whether diabetes leads to changes in ionotropic glutamate receptor subunit expression ...
NPY in rat retina is present in neurons, in endothelial cells and also in micro...
Álvaro, Ana Rita; Rosmaninho-Salgado, Joana; Santiago, Ana Raquel; Martins, João; Aveleira, Célia; Santos, Paulo F.; Pereira, Tiago; Gouveia, DenisaNPY is present in the retina of different species but its role is not elucidated yet. In this work, using different rat retina in vitro models (whole retina, retinal cells in culture, microglial cell cultures, rat Müller cell line and retina endothelial cell line), we demonstrated that NPY staining is present in the retina in different cell types: neurons, macroglial, microglial and endothelial cells. Retinal c...
3-D wave propagation in fluid-filled irregular boreholes in elastic formations
Tadeu, António J. B.; Santos, Paulo F. A.Different seismic testing techniques rely on the propagation of acoustic waves in fluid-filled boreholes from sources placed within the borehole and in the solid media. The interpretation of the signals recorded relies on understanding how waves propagate in the borehole and its immediate vicinity. It is known that very complex wave patterns can arise, depending on the distance between the source and the receiv...
Adenosine A1 receptors inhibit Ca2+ channels coupled to the release of ACh, but...
Santos, Paulo F.; Caramelo, Olga L.; Carvalho, Arsélio P.; Duarte, Carlos B.We investigated the effect of adenosine A1 receptors on the release of acetylcholine (ACh) and GABA, and on the intracellular calcium concentration ([Ca2+]i) response in cultured chick amacrine-like neurons, stimulated by KCl depolarization. The KCl-induced release of [3H]ACh, but not the release of [14C]GABA, was potentiated when adenosine A1 receptor activation was prevented by perfusing the cells with adenos...
Characterization of ATP release from cultures enriched in cholinergic amacrine-...
Santos, Paulo F.; Caramelo, Olga L.; Carvalho, Arsélio P.; Duarte, Carlos B.Adenosine triphosphate (ATP) has been proposed to play a role as a neurotransmitter in the retina, but not much attention has been given to the regulation of ATP release from retinal neurons. In this work, we investigated the release of ATP from cultures enriched in amacrine-like neurons. Depolarization of the cells with KCl, or activation of alpha-amino-3-hydroxy- 5-methyl-4-isoxazole-propionate (AMPA) recepto...
Corelease of two functionally opposite neurotransmitters by retinal amacrine ce...
Duarte, Carlos B.; Santos, Paulo F.; Carvalho, Arsélio P.The Dale's law postulates that a neuron releases the same neurotransmitter from all its branches. In the case of mulitple neurotransmitters it would require all transmitters to be released from all branches. The retinal cholinergic amacrine cells contain and release &ggr;-aminobutyric (GABA) and, therefore, if GABA and acetylcholine (ACh) are released at the same sites, this could mean that amacrine cells simul...
Metabotropic glutamate receptors modulate [3H]acetylcholine release from cultur...
Caramelo, Olga L.; Santos, Paulo F.; Carvalho, Arsélio P.; Duarte, Carlos B.Retinal amacrine cells express metabotropic glutamate receptors (mGluRs), but their physiological role is unknown. We investigated the effect of mGluR on [3H]acetylcholine release ([3H]ACh) from cultured chick amacrine-like neurons. Activation of group III mGluR with the agonist L(+)-2-amino-4-phosphonobutyric acid (L-AP4) inhibited [3H]ACh release evoked by 25 mM KCl in a dose-dependent manner, and this effect...
Glutamate in Life and Death of Retinal Amacrine Cells*
Duarte, Carlos B.; Ferreira, Ildete L.; Santos, Paulo F.; Carvalho, Ana L.; Agostinho, Paula M.; Carvalho, Arsélio P.1. Glutamate is the neurotransmitter released by bipolar cells at their synapses with amacrine cells. The amacrine cells express ionotropic (NMDA, AMPA and kainate) and metabotropic (mGluR1, mGluR2, mGluR4 and mGluR7) glutamate receptors and may take up glutamate from the synaptic cleft. ; http://www.sciencedirect.com/science/article/B6T71-3WDCGNH-6/1/585429baef39660288a51842ff1b4c33
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