Dendritic Localization and Exocytosis of NAAG in the Rat Hippocampus

While a lot is known about classical, anterograde neurotransmission, less is known about the mechanisms and molecules involved in retrograde neurotransmission. Our hypothesis is that N-acetylaspartylglutamate (NAAG), the most abundant dipeptide in the brain, may act as a retrograde transmitter in the brain. NAAG was predominantly localized in dendritic compartments of glutamatergic synapses in the intact hippocampus, where it was present in close proximity to synaptic-like vesicles. In acute hippocampal slices, NAAG was depleted from postsynaptic dendritic elements during neuronal stimulation induced by depolarizing concentrations of potassium or by exposure to glutamate receptor (GluR) agonists. The depletion was completely blocked by botulinum toxin B and strictly dependent on extracellular calcium, indicating exocytotic release. In contrast, there were low levels of NAAG and no effect by depolarization or GluR agonists in presynaptic glutamatergic terminals or GABAergic pre- and postsynaptic elements. Together these data suggest a possible role for NAAG as a retrograde signaling molecule at glutamatergic synapses via exocytotic release.

Very Long Persistence of Botulinum Toxin B in a Patient’s Serum

Background: Botulinum toxins (BoNT) type A, B, E, F may induce a serious neuroparalytic illness in humans. Botulism can be transmitted via three routes: foodborne, wound and intestinal (in situ toxemia generally observed in infants and/or in immunocompromised adults) botulism. Case Report: A case of human botulism type B due to the consumption of an imported dried ham is reported. Laboratory results confirmed the diagnosis using the mouse bioassay and the qPCR method. Botulinum toxin was still detected in the serum up to 29 days after food consumption while it was not detected anymore in the faeces. Conclusion: The described case highlights i) prolonged presence of BoNT B in the serum and ii) the risks related to the preparation of artisanal products as well as the importance of an efficient communication to citizens regarding preservation methods of household products.