RESUMEN

Cholinergic projections from the brainstem serve as important modulators of activity in visual thalamic nuclei such as the dorsal lateral geniculate nucleus (dLGN). While these projections have been studied in several mammals, a comprehensive examination of their organization in the mouse is lacking. We used the retrograde transport of viruses or cholera toxin subunit B (CTB) injected in the dLGN, immunocytochemical labeling with antibodies against choline acetyltransferase (ChAT), brain nitric oxide synthase (BNOS), and vesicular acetylcholine transporter (VAChT), ChAT-Cre mice crossed with a reporter line (Ai9), as well as brainstem virus injections in ChAT-Cre mice to examine the pattern of thalamic innervation from cholinergic neurons in the pedunculopontine tegmental nucleus (PPTg), laterodorsal tegmental nucleus (LDTg), and the parabigeminal nucleus (PBG). Retrograde tracing demonstrated that the dLGN receives input from the PPTg, LDTg, and PBG. Viral tracing in ChAT-Cre mice and retrograde tracing combined with immunocytochemistry revealed that many of these inputs originate from cholinergic neurons in the PBG and PPTg. Most notable was an extensive cholinergic projection from the PBG which innervated most of the contralateral dLGN, with an especially dense concentration in the dorsolateral shell, as well as a small region in the dorsomedial pole of the ipsilateral dLGN. The PPTg was found to provide a sparse somewhat diffuse innervation of the ipsilateral dLGN. Neurons in the PPTg co-expressed ChAT, BNOS, and VAChT, whereas PBG neurons expressed ChAT, but not BNOS or VAChT. These results highlight the presence of distinct cholinergic populations that innervate the mouse dLGN.

Asunto(s)

Cuerpos Geniculados , Tálamo , Animales , Colina O-Acetiltransferasa/metabolismo , Colinérgicos , Fibras Colinérgicas/metabolismo , Neuronas Colinérgicas/metabolismo , Mamíferos , Ratones , Tálamo/metabolismo , Proteínas de Transporte Vesicular de Acetilcolina

RESUMEN

BACKGROUND: Ascorbate and neuronal-derived nitric oxide (NO) play regulatory roles in the brain that tare dependent on their compartmentalization and diffusion. Glutamatergic activation triggers both ascorbate fluxes toward extracellular medium and NO production. The information on the profiles of change in time and space upon glutamatergic activation is scarce and yet this knowledge is important for the understanding of ascorbate and NO functions in vivo, in particular in the case of a coupled interaction between both dynamics. HYPOTHESIS: NO produced upon NMDA receptor activation is a modulator of ascorbate release to the extracellular space. METHODS: In this work, carbon fiber microelectrodes for simultaneous measurements of these substances in the hippocampus were used to collect information about ascorbate and NO dynamic profiles in real time. RESULTS: Glutamate stimulation evoked transient ascorbate and NO signals with high degree of spatial and temporal correlation between them. Combined experiments encompassing direct stimulus with NO and inhibitors of glutamate uptake and nNOS provided additional evidence supporting the modulator role of NO in the release of ascorbate to the extracellular space. CONCLUSIONS: The coupling between NO and ascorbate upon glutamatergic activation points to a functional impact on the activities of both compounds and, although the precise molecular mechanism needs to be clarified, such a coupling lays the foundations for new regulatory mechanisms in the brain.

Asunto(s)

Ácido Ascórbico/metabolismo , Ácido Glutámico/metabolismo , Hipocampo/metabolismo , Neuronas/metabolismo , Óxido Nítrico/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Animales , Ascorbato Oxidasa/metabolismo , Carbono , Fibra de Carbono , Inhibidores Enzimáticos/farmacología , Espacio Extracelular/efectos de los fármacos , Espacio Extracelular/metabolismo , Hipocampo/efectos de los fármacos , Indazoles/farmacología , Masculino , Microelectrodos , N-Metilaspartato/metabolismo , Neuronas/efectos de los fármacos , Óxido Nítrico Sintasa de Tipo I/antagonistas & inhibidores , Óxido Nítrico Sintasa de Tipo I/metabolismo , Ratas Wistar

RESUMEN

Objective:To investigate effects of propofol on nitric oxide synthase (NOS) activity and nitric oxide (NO)output of rat brain. Method: Sixteen SD rats were divided randomly into two groups. The animals were administered introperitoneally(ip) normal saline 10 ml?kg~(-1)(control group)or propofol 100mg?kg~(-1)(propofolgroup),respectively. These rats were decapitated immediately after having disappeared righting reflex. After rapid removal of cerebellum, brain stem,hippocampus and cerebral cortex,tissues were homogenized and centrifuged. NOS activity and NO output were assayed with spectrophotometric analysis. Result: In propofol group,NOS activity was significantly inhibited, NO outpul was significantly reduced in cerebellum, brain stem,hippoeampus and cerebral cortex as compared with those of control group(P