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Adenosine blocks hormone‐induced meiotic maturation by suppressing purine de novo synthesis
Author(s) -
Downs Stephen M.
Publication year - 2000
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/(sici)1098-2795(200006)56:2<172::aid-mrd8>3.0.co;2-2
Subject(s) - biology , inosine , adenosine , medicine , endocrinology , hypoxanthine , de novo synthesis , purine metabolism , germinal vesicle , azaserine , purine , pentose phosphate pathway , follicle stimulating hormone , inosine monophosphate , glycolysis , oocyte , hormone , metabolism , biochemistry , nucleotide , luteinizing hormone , microbiology and biotechnology , amino acid , enzyme , embryo , glutamine , gene
We have examined adenosine (Ado) suppression of FSH‐induced germinal vesicle breakdown (GVB) and its relationship to purine de novo synthesis. Oocyte‐cumulus cell complexes (OCC) from PMSG‐primed, immature mice were cultured 17–18 hr in medium containing 4 mM hypoxanthine (HX) or 300 μM dibutyryl cAMP (dbcAMP) to maintain meiotic arrest, and FSH was added to stimulate meiotic maturation. In the absence of FSH, Ado (1–250 μM) had no effect in dbcAMP‐arrested oocytes but dose‐dependently suppressed maturation in HX‐treated oocytes. FSH‐induced maturation was prevented by Ado, though more effectively in dbcAMP‐supplemented cultures. Ado affected the magnitude, but not the kinetics pattern, of the response to FSH. Inosine also blocked meiotic induction, but only in dbcAMP‐arrested oocytes. Purine de novo synthesis was nearly doubled in OCC by FSH treatment, and this response was completely prevented by Ado. FSH had no effect on HX salvage, although Ado reduced this activity by 98%. Inosine effects on metabolism were intermediate between the control and Ado groups. Experiments with radiolabeled energy substrates showed that Ado suppressed FSH activation of the pentose phosphate pathway but did not prevent significant activation of glycolysis or oxidation of pyruvate. Finally, in cultured follicles from primed mice, hCG‐induced maturation was blocked by Ado as effectively as by the purine de novo synthesis inhibitor, azaserine. It is concluded that Ado has an inhibitory action on hormone‐induced maturation that is due, at least in part, to suppression of glucose metabolism, leading to compromised purine de novo synthesis. Mol. Reprod. Dev. 56:172–179, 2000. © 2000 Wiley‐Liss, Inc.