Involvement of cytosolic phospholipase A2 in the ovulatory process in gonadotropin-primed immature rats.
The preovulatory LH surge induces a remarkable increase in ovarian prostaglandins (PGs) which help to mediate the ovulatory process. We investigated whether cytosolic phospholipase A2 (cPLA2) has a role in this PG production in PMSG/hCG-primed immature rats. The immunoreactive signal for cPLA2 was localized in both thecal and granulosa layers of mature follicles and became evident in response to gonadotropins. The PLA2 activity in the whole ovarian cytosol rose slightly after PMSG stimulation, persisted relatively constant until 24 h after hCG injection and thereafter increased gradually. Intra-ovarian bursal injection of arachidonyl trifluoromethyl ketone, a specific inhibitor for cPLA2 ( 1.0-3.0 mg/ovary), significantly reduced ovarian PGE2 content and the ovulation rate. These results suggest that cPLA2 exists in periovulatory follicles and functions in PG production related to the ovulation process.
Kurusu
S
S
Laboratory of Veterinary Physiology, Kitasato University School of Veterinary Medicine and Animal Sciences, Towada, Aomori, Japan. kurusu@vmas.kitasato-u.ac.jp
Iwao
M
M
Kawaminami
M
M
Hashimoto
I
I
D000818:Animals; D001095:Arachidonic Acids / Q000008:administration & dosage / Q000494:pharmacology; D003338:Corpus Luteum / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology*; D015777:Eicosanoids / Q000096:biosynthesis; D005260:Female; D006062:Gonadotropins / Q000494:pharmacology*; D006107:Granulosa Cells / Q000378:metabolism; D007150:Immunohistochemistry; D010053:Ovary / Q000033:anatomy & histology / Q000378:metabolism; D010060:Ovulation / Q000502:physiology*; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000502:physiology*; D054467:Phospholipases A2; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D001095:Arachidonic Acids; D015777:Eicosanoids; D006062:Gonadotropins; C081565:arachidonyltrifluoromethane; D010741:Phospholipases A; D054467:Phospholipases A2