Browsing by Author "Onate-Ponce, Alejandro"

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    Applying the area fraction fractionator (AFF) probe for total volume estimations of somatic, dendritic and axonal domains of the nigrostriatal dopaminergic system in a murine model
    (2024) Onate-Ponce, Alejandro; Munoz-Munoz, Catalina; Catenaccio, Alejandra; Court, Felipe A.; Henny, Pablo
    Background: The Cavalieri estimator is used for volume measurement of brain and brain regions. Derived from this estimator is the Area Fraction Fractionator (AFF), used for efficient area and number estimations of small 2D elements, such as axons in cross-sectioned nerves. However, to our knowledge, the AFF has not been combined with serial sectioning analysis to measure the volume of small-size nervous structures. New method: Using the nigrostriatal dopaminergic system as an illustrative case, we describe a protocol based on Cavalieri's principle and AFF to estimate the volume of its somatic, nuclear, dendritic, axonal and axon terminal cellular compartments in the adult mouse. The protocol consists of (1) systematic random sampling of sites within and across sections in regions of interest (substantia nigra, the nigrostriatal tract, caudate-putamen), (2) confocal image acquisition of sites, (3) marking of cellular domains using Cavalieri's 2D point-counting grids, and 4) determination of compartments' total volume using the estimated area of each compartment, and between-sections distance. Results: The volume of the nigrostriatal system per hemisphere is 0.38 mm3, with 5 % corresponding to perikarya and cell nuclei, 10 % to neuropil/dendrites, and 85 % to axons and varicosities. Comparison with existing methods: In contrast to other methods to measure volume of discrete objects, such as the optical nucleator or 3D reconstructions, it stands out for its versatility and ease of use. Conclusions: The use of a simple quantitative, unbiased approach to assess the global state of a system may allow quantification of compartment-specific changes that may accompany neurodegenerative processes.
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    Organization of the Catecholaminergic System in the Short-Lived Fish Nothobranchius furzeri
    (2021) Borgonovo, Janina; Ahumada-Galleguillos, Patricio; Onate-Ponce, Alejandro; Allende-Castro, Camilo; Henny, Pablo; Concha, Miguel L.
    The catecholaminergic system has received much attention based on its regulatory role in a wide range of brain functions and its relevance in aging and neurodegenerative diseases. In the present study, we analyzed the neuroanatomical distribution of catecholaminergic neurons based on tyrosine hydroxylase (TH) immunoreactivity in the brain of adult Nothobranchius furzeri. In the telencephalon, numerous TH+ neurons were observed in the olfactory bulbs and the ventral telencephalic area, arranged as strips extending through the rostrocaudal axis. We found the largest TH+ groups in the diencephalon at the preoptic region level, the ventral thalamus, the pretectal region, the posterior tuberculum, and the caudal hypothalamus. In the dorsal mesencephalic tegmentum, we identified a particular catecholaminergic group. The rostral rhombencephalon housed TH+ cells in the locus coeruleus and the medulla oblongata, distributing in a region dorsal to the inferior reticular formation, the vagal lobe, and the area postrema. Finally, scattered TH+ neurons were present in the ventral spinal cord and the retina. From a comparative perspective, the overall organization of catecholaminergic neurons is consistent with the general pattern reported for other teleosts. However, N. furzeri shows some particular features, including the presence of catecholaminergic cells in the midbrain. This work provides a detailed neuroanatomical map of the catecholaminergic system of N. furzeri, a powerful aging model, also contributing to the phylogenetic understanding of one of the most ancient neurochemical systems.