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Speaker Detail

Professor Andrea Falqui

King Abdullah University of Science & Technology, Saudi Arabia

Biography

‚ÄčProfessor Falqui's research interests lie in the frontier between  material science and bioscience. His main expertise is in electron  microscopy both in scanning and transmission mode and related  spectroscopies applied to nano-shaped inorganic materials and  biomaterials. In addition, his studies also concern the magnetic  behavior of nanoparticles by superconducting quantum interference device  (SQUID) magnetometry.

Abstract

Impairing long-term memory by inhibiting brain glycogenolysis: a 3D-ulstrastructure study


Serial block-face scanning electron microscopy (SBF-SEM) has incessantly become popular for 3D tissues 3D-reconstruction in neuroscience. It consists in a semi-automated process of ultramicrotomy sectioning, blocks of tissue SEM imaging and following 3D reconstruction. This technique provides enough resolution to resolve ultrastructural details such as synapses, mitochondria, synaptic vesicles and post-synaptic features, with a field of view that could allow dense reconstruction of the neuronal network.
Here we applied SBF-SEM to perform accurate 3D analysis of morphology, structure and distribution of excitatory hippocampal synapses, mitochondria and glycogen clusters on brains of adult mice 24 hours after a novel-object recognition (NOR) behavioural training. We then impaired long-term memory formation by an intra-hippocampal injection of a potent inhibitor of glycogenolysis, 1,4-Dideoxy-1,4-imino-D-arabinitol hydrochloride (DAB), which is known to be able to decrease the lactate gradient between the extracellular space and the neurons, and again studied the hippocampal neuropil 3D ultrastructure.This study basically aimed at revealing the morphological changes induced by the DAB administration related to the long-term memory impairment.
We discovered that 24 hours after NOR training density and size of spines increased significantly if compared to those of naive animals, together with the appearance of glycogen clusters. Conversely, the DAB treatment impaired the formation of new spines. Besides, in order to rescue both behavioural and related morphological features impaired by the sole DAB administration, we injected L-Lactate together with DAB, and we observed that both memory and spine density were recovered, however with no spine size growth, nor the formation of glycogen clusters. These findings suggest that the basis of such structural impairments might result from an energetic deficit. Furthermore, 3D analyses of dendritic mitochondria revealed indeed their impaired fission, which was again rescued by L-Lactate administration. Altogether, these evidences indicate that impairing upstream lactate source glycogen results in a related energetic deficit, thus leading the network to lose its structural plasticity features.
 

All sessions by Professor Andrea Falqui

  • MondayApril 9
11:25 AM

"Impairing long-term memory by inhibiting brain glycogenolysis: a 3D-ulstrastructure study"