Abstract
Arachidonic acid (AA), a compound secreted by Sertoli cells (SC) in a FSH-dependent manner, is able to induce the release of Ca2+ from internal stores in round spermatids and pachytene spermatocytes. In this study, the possible site(s) of action of AA in round spermatids, the signalling pathways associated and the intracellular Ca2+ stores targeted by AA-induced signalling were pharmacologically characterized by measuring intracellular Ca2+ using fluorescent Ca2+ probes. Our results suggest that AA acts by interacting with a fatty acid G protein coupled receptor, initiating a G protein signalling cascade that may involve PLA2 and ERK activation, which in turn opens intracellular ryanodine-sensitive channels as well as NAADP-sensitive channels in acidic intracellular Ca2+ stores. The results presented here also suggest that AMPK and PKA modulate this AA-induced Ca2+ release from intracellular Ca2+ stores in round spermatids. We propose that unsaturated free fatty acid lipid signalling in the seminiferous tubule is a novel regulatory component of rat spermatogenesis.
MeSH terms
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Animals
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Arachidonic Acid / pharmacology*
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Calcium / metabolism*
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Cells, Cultured
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Dose-Response Relationship, Drug
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Endoplasmic Reticulum / drug effects*
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Endoplasmic Reticulum / metabolism
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Endosomes / drug effects
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Endosomes / metabolism
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Kinetics
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MAP Kinase Signaling System / drug effects*
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Male
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Microscopy, Confocal
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NADP / analogs & derivatives
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NADP / metabolism
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Phospholipases A2 / metabolism
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Rats, Sprague-Dawley
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Receptors, G-Protein-Coupled / agonists*
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Receptors, G-Protein-Coupled / metabolism
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Salicylates / pharmacology
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Sesterterpenes / pharmacology
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Spermatids / cytology
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Spermatids / drug effects*
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Spermatids / metabolism
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Testis / cytology
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Testis / drug effects
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Testis / metabolism
Substances
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Ffar4 protein, rat
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Receptors, G-Protein-Coupled
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Salicylates
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Sesterterpenes
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grifolic acid methyl ether
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nicotinic acid adenine dinucleotide phosphate acetoxymethyl ester
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Arachidonic Acid
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NADP
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Phospholipases A2
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Calcium
Grants and funding
This work was supported by Fondecyt grant numbers 1110267 and 1140758; and PUCV grant number 125.754/2011 125792/2014 to JGR; and Consejo Nacional de Ciencia y Tecnología (CONACyT-Mexico) (128566 to CT), Dirección General de Asuntos del Personal Académico/ Universidad Nacional Autónoma de México (DGAPA/ UNAM) (IN202212-3 to CT) and The Alexander von Humboldt Foundation (to CT). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.