Poster
# 22
Poster |
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6th Internet World Congress for Biomedical Sciences |
José Manuel Martínez-Martos(1), María Jesús Ramírez-Expósito(2), María Dolores Mayas-Torres(3), Isabel Prieto-Gómez(4), Manuel Ramírez-Sánchez(5)
(1)(3)(4)(5)Unit of Physiology. University of Jaén - Jaén. Spain
(2)Unit of Physiology. University of Jaen - Jaén. Spain
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[Neuroscience] |
[Physiology] |
Synaptosomes have been widely used to understand the neurochemical mechanisms which underlie to the brain function, including uptake/release of neurotransmitters (Sheng, Westenbroek & Catteral, 1998; Langley & Grant, 1997; Erecinska, Zaleska, Chiv & Nelson, 1991; Szutowicz, Tomaszewicz & Bielarczyk, 1997), intracellular free calcium homeostasis (Sheng et al. 1998; Huang, Toral-Barza & Gibson, 1991), second messenger or protein studies (Hertz & Peng, 1992) and energy metabolism (Curti, Izzo, Brambilla, Faccheti, Sangiovanni & Brambilla, 1995; Erecinska, Nelson & Silver, 1996). These studies include the variations on the functional status of this subcellular fraction depending of its depolarization by K+ and/or its activation with different substances (including ATP). Furthermore, several reports describe the metabolic status of rodent synaptosomal mitochondria as a key factor of dysfunctions in different brain diseases such as traumatic spinal cord injury (Azbill, Mu, Bruce-Keller, Mattson & Springer, 1997), ischemia (Santos, Moreno & Carvalho, 1996), reactive oxygen species formation and membrane lipid peroxidation (Keller et al. 1997), aging (Gabbita, Butterfield, Hensley, Shaw & Carney, 1997), chronic lead intoxication (Struzynska, Dabrowska-Bouta & Rafalowska, 1997) or drug-induced neurotoxicity (Callahan, Yuan, Strover, Hatzidimitrion & Ricaurte, 1998). Our results describe the physiological changes in the energetic status of rodent cortical brain synaptosomes under three conditions:1) in a resting (basal) state; 2) after depolarization with high K+, where the respiration is accelerated by increased Na+-permeability through the plasma membrane, which stimulates the function of Na+/K+ ATPase, and thus increases the energy demand (Erecinska, Nelson, Deas & Silver, 1996; Raatikainen, Kauppinen, Komulainen, Taipale, Pirttila & Tuomisto, 1991); 3) after stimulation with ATP, acting through its ionotropic and metabotropic receptors (Zimmermann, 1994). Our results showed a similar MTT formazan production in rat and mouse synaptosomes, which is in agreement with previous reports that demonstrated an essentially identical behaviour between synaptosomes prepared from mouse, rat, dog and chicken cerebra in several energy metabolism parameters (Kyriazy & Basford, 1986), other than the use of MTT assay.
Although it is widely assumed that MTT is reduced by active mitochondria in living cells, and MTT assay is near to be exclusively used for measuring cell proliferation and cytotoxicity, we report that MTT assay could be useful as an index of the functional status and energetic behaviour of rodent brain cortex synaptosomes, which could be interesting to relate with several other biochemical and physiological parameters in different types of studies under resting and/or stimulating conditions.
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[Neuroscience] |
[Physiology] |
