RESUMEN
The intergeniculate leaflet (IGL) is a flat thalamic nucleus implicated in the modulation of circadian rhythmicity. In rat, two main GABAergic subpopulations can be distinguished in the IGL: neurons synthesizing neuropeptide Y (NPY), which directly innervates the suprachiasmatic nuclei, and enkephalinergic cells, which connect contralaterally located leaflets. The aim of this study was to evaluate possible effects of inner IGL neurotransmitters on the spontaneous and synaptic activity of IGL neurons. The data presented in this article provide evidence that enkephalin, and not NPY, could act upon the majority of IGL neurons. Moreover, we investigated the type of opioid receptor activated by enkephalin and showed that the µ-receptor is functionally predominant in the IGL. The application of met-enkephalin not only robustly hyperpolarized IGL neurons (both putatively NPY-synthesizing and putatively enkephalinergic neurons), but it also was able to inhibit GABAergic and glutamatergic synaptic transmission. Based on this and previous studies, we hypothesize that IGL enkephalinergic neurons may act as powerful interneurons that inhibit themselves and NPY-synthesizing neurons, also in the contralaterally located IGL.
Asunto(s)
Relojes Biológicos/fisiología , Encefalinas/metabolismo , Neuronas/metabolismo , Neuropéptido Y/metabolismo , Núcleos Talámicos/metabolismo , Animales , Relojes Biológicos/efectos de los fármacos , Encefalinas/administración & dosificación , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Potenciales Postsinápticos Excitadores/fisiología , Ácido Glutámico/metabolismo , Inmunohistoquímica , Potenciales Postsinápticos Inhibidores/efectos de los fármacos , Potenciales Postsinápticos Inhibidores/fisiología , Masculino , Potenciales Postsinápticos Miniatura/efectos de los fármacos , Potenciales Postsinápticos Miniatura/fisiología , Neuronas/citología , Neuronas/efectos de los fármacos , Neurotransmisores/administración & dosificación , Técnicas de Placa-Clamp , Ratas Wistar , Transmisión Sináptica/efectos de los fármacos , Transmisión Sináptica/fisiología , Núcleos Talámicos/citología , Núcleos Talámicos/efectos de los fármacos , Técnicas de Cultivo de Tejidos , Ácido gamma-Aminobutírico/metabolismoRESUMEN
A novel and promising method of microcystin-LR (mcyst-LR) degradation is reported. The decomposition of this cyanobacterial toxin using Fenton reagent has been observed with very low initial concentrations of H2O2 and Fe2+ (Fe3+) in the reaction mixture. Mcyst-LR was isolated from a laboratory culture of Microcystis aeruginosa PCC 7813. The initial concentration of the toxin used exceeded by several orders of magnitude those occurring naturally in lakes and drinking water. Even so, the decomposition of the toxin was complete after 30 min.
