In vivo evidence for possible up-regulating roles of lysophosphatidic acid around fertilization in rats

Altered ovarian tissue level of lysophosphatidic acid and mRNA expressions of its metabolic enzymes and receptors in rats received gonadotropin-hyperstimulation

Lysophosphatidic acid (LPA), a well-studied member of the lysophospholipid family, is known to exert an important bio-effect on oocyte maturation and ovulation in mammals. We attempted to determine how follicle maturation in the rat ovary affects the levels of LPA and its precursor lysophospholipids, as well as mRNA levels of LPA-producing and -degrading enzymes and LPA receptors in rats that received gonadotropin-hyper-stimulation. Tissue levels of lysophospholipids were quantified by LC-MS/MS, and relative mRNA expression levels of LPA-producing and -degrading enzymes, and LPA receptors were measured by RT-PCR. Tissue levels of n-6 polyunsaturated LPAs and LPCs were higher in the ovaries of rats after receiving human chorionic gonadotropin, unlike the distinct profiles of n-3 polyunsaturated LPAs, which had lower levels, and LPCs which had higher levels, after the gonadotropin treatment. The effects of different levels of other polyunsaturated lysophospholipids were variable: decreased levels of lysophosphatidylglycerol, and unaltered levels of lysophosphatidylethanolamine, lysophosphatidylinositol, and lysophosphatidylserine. The results indicate that expression of mRNA levels of autotaxin and acylglycerol kinase were reduced and expression of lipid phosphate phosphatase 3 was elevated, whereas expressions of two membrane phosphatidic acid phosphatases (A1α and A1β) and lipid phosphate phosphatase 1 were essentially unaltered in rat ovary at several stages after ovary hyperstimulation. After the gonadotropin treatment, the expression levels of all LPA receptors except LPA3 were decreased at various times. These results are discussed with respect to the physiological processes of the ovarian environment and development in rats.

Expression of lysophosphatidic acid receptors in the rat uterus: cellular distribution of protein and gestation-associated changes in gene expression

Though lysophosphatidic acid (LPA) shows a variety of regulatory roles in reproduction, its action mechanisms in the gestational organs are still largely unknown. We here characterized cellular distribution of its six kinds of specific receptors (LPA1-6) in rat uteri by immunohistochemistry and quantitatively analyzed changes in Lpar1-6 mRNAs expression throughout pregnancy. Among LPA1-6, evident expression of LPA3, LPA4, and LPA6 was immunologically detected and less expression of immunoreactive LPA1 and LPA2 was also found. Luminal and glandular epithelial cells, stromal cells, and myometrial cells are sites of positive immunoreactions, and they are all likely to express three or more subtypes. All of Lpar1-6 mRNAs were expressed, and their alterations were variable depending on subtypes and gestational age. The present information suggests that diverse actions of LPA in the uterus involve varied expression of LPA receptors dependent on tissue/cell types, receptor subtype(s), and organ reproductive states and helps to understand uterine biology of LPA.

Pathophysiological changes in experimental polycystic ovary syndrome in female albino rats: Using either hemin or L-arginine

Polycystic ovary syndrome (PCOS), one of the important endocrine disorders affecting females in the reproductive age, is caused mainly by an abnormal oxidation status that subsequently causes inflammatory conditions. Thus, this study aims to examine the possible individual prophylactic effects of gasotransmitters, hemin, or L-arginine in letrozole-induced PCOS. Fifty adult female albino rats were used and separated into a control group, which received the vehicle; a letrozole-induced PCOS group (L), which received letrozole orally at a dose level of 1 mg/kg for 21 days; a letrozole+hemin (L+H) group, which received letrozole plus hemin at a dose level of 25 mg/kg injected IP twice per week for 21 days; and a letrozole+L-arginine (L+A) group, which received letrozole plus L-arginine at a dose level of 200 mg/kg orally for 21 days. During PCO induction, the body weight and Lee index were measured. Serum glucose, insulin, lipid profile, gonadotrophic hormones, testosterone, estrogen, and tumor necrosis factor alpha were assayed, while ovarian tissues were analyzed to measure the oxidative state and histopathological changes. Our results proved that either hemin or L-arginine administration could improve the oxidative state, the inflammatory reaction, the hormonal imbalance, and the metabolic disturbances in PCO rats, which was confirmed by a histopathological examination of the rats' ovaries. In conclusion, either hemin or L-arginine had protective effects against PCOS with better pathophysiological changes with hemin.