title: Effects of Fatty Acids on Intracellular [Ca2+], Mitochondrial Uncoupling and Apoptosis in Rat Pachytene Spermatocytes and Round Spermatids.
abstract: The aim of this work was to explore the ability of free arachidonic acid, palmitic acid and the unsaturated fatty acids oleic acid and docosahexaenoic acid to modify calcium homeostasis and mitochondrial function in rat pachytene spermatocytes and round spermatids. In contrast to palmitic acid, unsaturated fatty acids produced significant increases in intracellular calcium concentrations ([Ca2+]i) in both cell types. Increases were fatty acid specific, dose-dependent and different for each cell type. The arachidonic acid effects on [Ca2+]i were higher in spermatids than in spermatocytes and persisted when residual extracellular Ca2+ was chelated by EGTA, indicating that the increase in [Ca2+]i originated from release of intracellular calcium stores. At the concentrations required for these increases, unsaturated fatty acids produced no significant changes in the plasma membrane potential of or non-specific permeability in spermatogenic cells. For the case of arachidonic acid, the [Ca2+]i increases were not caused by its metabolic conversion to eicosanoids or anandamide; thus we attribute this effect to the fatty acid itself. As estimated with fluorescent probes, unsaturated fatty acids did not affect the intracellular pH but were able to induce a progressive decrease in the mitochondrial membrane potential. The association of this decrease with reduced reactive oxygen species (ROS) production strongly suggests that unsaturated fatty acids induced mitochondrial uncoupling. This effect was stronger in spermatids than in spermatocytes. As a late event, arachidonic acid induced caspase 3 activation in a dose-dependent manner both in the absence and presence of external Ca2+. The concurrent but differential effects of unsaturated fatty acids on [Ca2+]i and mitochondrial functions are additional manifestations of the metabolic changes that germ cells undergo during their differentiation.
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Paillamanque
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: Cristian
authors.initials: C
authors.lastname: Madrid
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: Emerson M
authors.initials: EM
authors.lastname: Carmona
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: Nelson
authors.initials: N
authors.lastname: Osses
authors.affiliation: Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Ricardo D
authors.initials: RD
authors.lastname: Moreno
authors.affiliation: Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB), Bahia Blanca, Argentina.
authors.forename: Gerardo M
authors.initials: GM
authors.lastname: Oresti
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: José A
authors.initials: JA
authors.lastname: Pino
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
authors.forename: Juan G
authors.identifier: http://orcid.org/0000-0002-3274-3605
authors.initials: JG
authors.lastname: Reyes
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D016718:Arachidonic Acid / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D004281:Docosahexaenoic Acids / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D013087:Spermatids / Q000166:cytology* / Q000378:metabolism; D013090:Spermatocytes / Q000166:cytology* / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D017382:Reactive Oxygen Species; D004281:Docosahexaenoic Acids; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D002118:Calcium