Role of P2-purinergic receptors in rat Leydig cell steroidogenesis.
The present study investigated the effects of extracellular ATP on the intracellular calcium ion concentration ([Ca2+]i) and testosterone production in isolated adult rat Leydig cells. This nucleotide caused an increase in [Ca2+]i, with a maximal effect at a concentration of 100 microM ATP, comprising a rapid initial spike followed by a long-lasting plateau. The first rapid spike was dependent on the release of Ca2+ from internal stores, since it also occurred in Ca(2+)-free medium and was abolished after depletion of internal stores with thapsigargin. The second, long-lasting, phase was dependent on the influx of Ca2+ from the extracellular medium. After 3 h of incubation, extracellular ATP stimulated testosterone secretion in a dose-dependent manner, with a maximal effect at 100 microM. Activation of steroidogenesis by ATP was fully dependent on the presence of Ca2+ in the external medium. Among different nucleotides, only ATP, adenosine 5'-[gamma-thio]triphosphate, UTP, benzoylbenzoic-ATP and 2-methylthio-ATP were effective in inducing both the rise in [Ca2+]i and testosterone secretion. These effects were blocked by preincubation of Leydig cells with oxidized ATP, an inhibitor of the P2Z-purinergic receptor subtype. These results show that rat Leydig cells possess P2-purinergic receptors whose activation triggers an increase in [Ca2+]i due to the release of Ca2+ from internal stores and Ca2+ influx from the external medium. The stimulatory effect of extracellular ATP on testosterone secretion seems to be coupled to the influx of Ca2+ from the external medium.
Foresta
C
C
Università di Padova, Italy.
Rossato
M
M
Nogara
A
A
Gottardello
F
F
Bordon
P
P
Di Virgilio
F
F
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007700:Kinetics; D007985:Leydig Cells / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008345:Manganese / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology*; D012265:Ribonucleotides / Q000494:pharmacology; D013739:Testosterone / Q000096:biosynthesis* / Q000378:metabolism
D018048:Receptors, Purinergic P2; D012265:Ribonucleotides; D013739:Testosterone; D008345:Manganese; C017199:2',3'-dialdehyde ATP; D000255:Adenosine Triphosphate; D002118:Calcium