In cattle and other species, the corpus luteum plays a central role in the regulation of cyclicity and maintenance of pregnancy. In the absence of fertilization and implantation, the corpus luteum undergoes functional and morphological regression or luteolysis. Luteal regression is initiated in domestic ruminants by surges of prostaglandin F2alpha (PGF2alpha) from the uterus. Despite intensive ...

background:   objective: this study was designed to evaluate effects of lithium chloride on the release of steroid hormones and steroidogenic enzymes in gonadotropin-stimulated rats.   materials and methods: immature 23 days old wistar rats were divided into 10 groups; each group comprised of 8 rats, and induced with single injection of pregnant mare’s serum gonadotrophin (pmsg) and followed by...

We investigated the potential direct effects of Tokishakuyakusan (TS) on progestin [progesterone and 20alpha-hydroxyprogesterone (20alpha-OH-P)] and cyclic adenosine-3',5'-monophosphate (cAMP) production in cultured rat luteal cells. In addition, we examined whether TS regulates the inhibitory effects of pituitary adenylate cyclase-activating polypeptide (PACAP), a newly found peptide, on lutei...

Ovarian, endometrial and myometrial cells and strips of longitudinal myometrium from cows on defined days of estrous cycle were treated for 24-72 h with different doses (1-100 ng/ml) of PCBs mixture (Aroclor 1248) or with one of PCB congeners (126, 77, 153). The administered doses of PCBs neither affected the viability of cells nor influenced the ovarian steroidogenesis as measured by progester...

OBJECTIVE To study the mechanism of thyroid hormone action on the activity of 3beta-hydroxysteroid dehydrogenase in the porcine corpus luteum. METHODS Pig ovaries were obtained from slaughterhouse animals. Luteal cells were isolated from mid-developing (5-7 days after ovulation) corpora lutea and incubated for 24 h with or without triiodothyronine. Trilostane, an inhibitor od 3beta-HSD that b...

Macrophages are prominent in the uterus and ovary at conception. Here we utilize the Cd11b-Dtr mouse model of acute macrophage depletion to define the essential role of macrophages in early pregnancy. Macrophage depletion after conception caused embryo implantation arrest associated with diminished plasma progesterone and poor uterine receptivity. Implantation failure was alleviated by administ...

In several species including the buffalo cow, prostaglandin (PG) F2α is the key molecule responsible for regression of corpus luteum (CL). Experiments were carried out to characterize gene expression changes in the CL tissue at various time points after administration of luteolytic dose of PGF2α in buffalo cows. Circulating progesterone levels decreased within 1 h of PGF2α treatment and evidenc...

OBJECTIVE: To investigate the influence of thyroid hormone on steroid production and cAMP accumulation in porcine theca (Tc) and granulosa cells (Gc) isolated from preovulatory follicles as well as in luteal cells isolated during the mid-developing luteal phase. METHODS: Granulosa and theca cells separated from pig ovarian follicles and pieces of corpora lutea were cultured in the incubation me...

Rat luteal cells utilize high-density lipoproteins (HDL) as a source of cholesterol for steroid synthesis. Both the free and esterified cholesterol of HDL are utilized by these cells. In this report, we have examined the relative uptake of free and esterified cholesterol of HDL by cultured rat luteal cells. Incubation of the cells with HDL labeled with [3H]cholesterol or [3H]cholesteryl linolea...