The present study provides evidence that the adult mammalian retina is highly sensitive to the excitotoxic action of NMDA. In particular, we have investigated the effects of a single intravitreal injection of different doses of N-methyl-D-aspartate (NMDA) (2–200 nmoles) on the adult rat retina. Morphological evaluation of transverse sections of retinae demonstrated a dose-dependent loss of cells in the ganglion cell layer (GCL) and a reduction in the thickness of the inner plexiform layer. No obvious alterations were noted in the more distal retinal layers. Quantitative analyses of Nissl-stained whole-mounted retinae revealed that administration of 20 nmoles of NMDA resulted in a 70% loss of cells with a soma diameter greater than 8 μm (presumed retinal ganglion cells); a 20% loss of cells with a soma diameter smaller than 8 μm (presumed displaced amacrine cells) was also observed. In addition, NMDA produced a dose-dependent decrease of retinal choline acetyltransferase (ChAT) activity, suggesting that NMDA affects cholinergic amacrine cells as well. MK-801, a non-competitive NMDA antagonist, completely prevented the NMDA-induced loss of cells in the GCL and blocked, in a dose-dependent manner, the NMDA-induced decrease of ChAT activity. The excitotoxic action of NMDA observed in these experiments is thus likely mediated through the NMDA receptor subtype. This ”in vivo” model may be utilized to identify potential drugs that antagonize or limit the deleterious effects consequent to NMDA receptor overstimulation in the central nervous system.

In this study, we injected 10 mg/kg kainate i.p. into rats. This resulted in a brain injury, which we quantified in the hippocampus, the amygdala, and the pyriform cortex. Neuronal damage was preceded by a set of typical behavioral signs and by biochemical changes (noradrenaline decrease and 5-hydroxyindoleacetic acid increase) in the affected brain areas. Melatonin (2.5 mg/kg) was injected i.p. four times: 20 min before kainate, immediately after, and 1 and 2 h after the kainate. The cumulative dose of 10 mg/kg melatonin prevented kainate-induced neuronal death as well as behavioral and biochemical disturbances. A possible mechanism of melatonin-provided neuroprotection lies in its antioxidant action. Our results suggest that melatonin holds potential for the treatment of pathologies such as epilepsy-associated brain damage, stroke, and brain trauma.

Abstract. VAMP/synaptobrevin is part of the synaptic vesicle docking and fusion complex and plays a central role in neuroexocytosis. Two VAMP (vesicle-associated membrane protein) isoforms are expressed in the nervous system and are differently distributed among the specialized parts of the tissue. Here, VAMP-1 and -2 are shown to be present in all rat tissues tested, including kidney, adrenal gland, liver, pancreas, thyroid, heart, and smooth muscle. The two isoforms are differentially expressed in various tissues and their level may depend on differentiation. VAMP-1 is restricted to exocrine pancreas and to kidney tubular cells, whereas VAMP-2 is the predominant isoform present in Langerhans islets and in glomerular cells. Both isoforms show a patchy vesicular intracellular distribution in confocal microscopy. The present results provide evidence for the importance of neuronal VAMP proteins in the physiology of all cells.UKARYOTIC cells possess organized secretory pathways for the exocytosis of proteins and other molecules. These secretory routes consist of several discrete membrane compartments and of transport vesicles that shuttle between these compartments (Rothman and

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Solid pseudopapillary tumor is a rare condition that should be taken into account for the differential diagnosis of pancreatic masses in pediatric age. Due to its favourable prognosis, surgical removal should be planned and done following the intraoperative findings.