Cellular and Molecular Neurobiology
Author: Sara Gonzalez | Email: saragonzalez@uca.edu.ar
Sara Gonzalez-Rodulfo1°3°, Ana Uceda2°,Héctor Ramiro Quintá2°3°, Alejandro Omar Sodero1°3°
1° Instituto de Investigaciones Biomédicas (BIOMED), Pontificia Universidad Católica Argentina (UCA), Buenos Aires, Argentina.
2° Laboratorio de Medicina Experimental “Dr. Jorge E. Toblli”, Hospital Alemán, Buenos Aires, Argentina.
3° Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
The decline of cognitive function with aging has been associated to synaptic dysfunction. In addition, alterations in the expression of neurotransmitter receptors have been postulated to significantly contribute to synaptic dysfunction.
We investigated the expression of the alpha4-containing nicotinic acetylcholine receptor (CHRNA4) in cortical inhibitory neurons, in a mouse model of physiological/normative aging, using 3-dimensional imaging of solvent cleared organs (3DISCO). Shortly, the brains of middle-aged and elderly mice were obtained after p-formaldehyde fixation and subjected to double immunofluorescence (IF). Once the IF was completed, the brain tissue was dehydrated with increasing concentrations of tetrahydrofuran and di-chloro-methane. Finally, the tissue was made transparent by immersion and gentle shaking in benzyl alcohol/benzyl benzoate. Using a confocal microscope, we captured 100-150 images in the z-plane to reconstruct the volumes. For the digital processing of volumes, we optimized and filtered the images of the z-stack, designed masks to segment the signals, and performed the quantifications by channel.
We detected a significant decrease in the number of inhibitory neurons (GAD67+) expressing the CHRNA4 in elderly mice, compared to middle-aged mice. This reduction was evident in the prefrontal and occipital cortices. Our results have relevance to understand a reduction in the inhibitory control over the glutamatergic neurons in the context of aging.