In this study we examined, in two experiments, patterns of follicular development and dominance under conditions heat stress. Estrous cycles were programmed to include waves (wave 1 2). On Day the estrous cycle (Day 0 = estrus), cows assigned randomly cooled (C; n 6) or heat-stressed (H; groups. experiment 1, on 12 prostaglandin (PG) F2α, was injected a controlled intravaginal drug release device (1.9 g progesterone) inserted (this removed 17). 2, PGF2α, 14. Ovarian structures examined daily...

The aim of this study was to characterize the immediate effects heat stress on plasma FSH and inhibin concentrations, its involvement in follicular dynamics during a complete oestrous cycle, examine possible delayed effect development. Holstein dairy cows were synchronized randomly assigned either cooled (n = 7) or heat-stressed 6) treatment groups. During control cows, which cooled, maintained normothermia, whereas exposed direct solar radiation, developed hyperthermia. At end cycle...

During the autumn, conception rate of dairy cattle in warm countries is low although ambient temperatures have decreased and cows are no longer exposed to summer thermal stress, indicating that there may be a delayed effect heat stress on fertility. Two experiments were conducted examine possible effects follicular characteristics steroid production at two distinct stages growth: medium-sized preovulatory follicles, 20 26 days after exposure, respectively. Lactating subjected for 12 h day an...

Effects of acute and seasonal heat stress on tonic GnRH-induced LH FSH secretion were examined during the early follicular phase oestrous cycle cows (n = 40). Prostaglandin F2α was injected day 11 ± 1 next blood samples collected at intervals 15–20 min for 14 h, i.m. injection GnRH given after 7 h. Treatments compared control versus sampling in winter, cooled chronic summer. Before injection, summer did not affect basal concentrations plasma LH, but lower pulse amplitude. However, with low...

This study was undertaken to investigate whether bovine granulosa and theca interna cells could be luteinized in vitro into luteal-like cells. Granulosa were cultured for 9 days the presence of forskolin (10 μM), insulin (2 μg/ml), insulin-like growth factor I (100 ng/ml), or a combination these agents. During first day culture, secreted estradiol androstenedione, respectively; progesterone rose only after 3–5 culture reached maximum on ninth culture. Cells incubated plus exhibited...

Endothelin-1 (ET-1) a vasoactive peptide, is synthesized and secreted by endothelial cells. In the bovine corpus luteum (CL), cells constitute major proportion (53.5%) of total CL This study was designed to examine effects ET-1 on luteal cell functions its involvement in action PGF2alpha. To better define implicated this process, we used slices, whole CL-derived cells, steroidogenic large (LLC) small (SLC) luteal-like High affinity binding sites for (K(d), approximately 0.3 x 10(-9)) were...

Prostaglandin F2alpha (PGF2alpha) has been recognized as the physiological luteolysin in ruminants and other species for more than three decades; however, mechanisms involved its action are poorly understood. We previously have shown that endothelin-1 (ET-1) mediates, at least part, of PGF2alpha, current study examines effect PGF2alpha on expression ET-1 bovine corpus luteum (CL). Endothelins (ETs) were extracted from CL, collected various times estrous cycle, highest levels found during...

Werecently compared prostaglandin F2alpha (PG)-induced global gene expression profiles in PG-refractory, bovine corpus luteum (CL) collected on Day 4 of the estrous cycle, versus PG-responsive, 11 CL. Transcriptome analyses led us to study regulation angiogenesis-related genes by PG and their functions luteal endothelial cells (ECs). We found that regulated angiogenesis-modulating factors a stage-dependent way. A robust increase FGF2 (mRNA protein) occurred PG-refractory CL promoting...

The role of tumor necrosis factor alpha (TNF alpha) and its type I receptor (TNFRI) in structural luteolysis was investigated. A semiquatitative reverse-transcription polymerase chain reaction (RT-PCR) used to characterize the pattern TNFRI mRNA expression within corpus luteum (CL) throughout estrous cycle cellular distribution. Increase levels recorded both regressed luteal tissue CL cows injected with prostaglandin F(2 alpha). All three major cell types composing CL, steroidogenic (large...

The aim of this study was to characterize the immediate effects heat stress on plasma FSH and inhibin concentrations, its involvement in follicular dynamics during a complete oestrous cycle, examine possible delayed effect development. Holstein dairy cows were synchronized randomly assigned either cooled (n = 7) or heat-stressed 6) treatment groups. During control cows, which cooled, maintained normothermia, whereas exposed direct solar radiation, developed hyperthermia. At end cycle...

Luteal regression is initiated by prostaglandin F2α (PGF2α). In domestic species and primates, demise of the corpus luteum (CL) enables development a new preovulatory follicle. However, during early stages cycle, which are characterized massive neovascularization, CL refractory to PGF2α. Our previous studies showed that endothelin-1 (ET-1), produced endothelial cells lining these blood vessels, plays crucial role PGF2α-induced luteolysis. Therefore, in this study, we compared effects PGF2α...

We have previously shown that arginine vasopressin (AVP) directly inhibits testicular steroidogenesis in vitro. In the present study, binding of neurohypophysial peptides to interstitial cells rat testis was studied using [3H]AVP as ligand. Interstitial were obtained from adult after collagenase dispersion and incubated with presence or absence unlabeled AVP. Binding equilibrium reached by 60 min at 4 C, while incubation higher temperatures (23 37 C) resulted an apparent decrease binding....

The objective of this study was to identify prostaglandin F(2α) (PG)-induced changes in the transcriptome bovine corpora lutea (CL) that are specific mature, PG-responsive (day 11) CL vs. developing 4) CL, which do not undergo luteolysis response PG administration. were collected at 0, 4, and 24 h after injection on days 4 11 estrous cycle (n = 5 per day time point), microarray analysis performed with GeneChip Bovine Genome Arrays. Data normalization affy package significance testing maanova...

Contents The bovine corpus luteum ( CL ) is a transient gland with life span of only 18 days in the cyclic cow. Mechanisms controlling development and secretory function may involve factors produced both within outside this gland. Although luteinizing hormone LH surge main trigger ovulation granulosa cells luteinization, many locally agents such as arachidonic acid AA metabolites, growth cytokines were shown to complement gonadotropins action process development. Bovine highly vascular...

LH and prostaglandin F2α (PGF2α) control the life span function of corpus luteum (CL). Nevertheless, identification various cell types (steroidogenic nonsteroidogenic) expressing receptors for these hormones remains controversial. In this study we characterized PGF2α receptor (r) expression in luteal using quantitative reverse transcription-polymerase chain reaction. We found, agreement with previously described functions PGF2α, that two steroidogenic types, as well endothelial cells,...

To examine hormonal regulation of genes pertinent to luteal steroidogenesis, bovine theca and granulosa cells derived from preovulatory follicles were cultured with various combinations forskolin insulin. On Day 8 culture, progesterone production was measured, mRNA levels steroidogenic factor-1 (SF-1), cytochrome P450 side-chain cleavage enzyme (P450scc), acute regulatory protein (StAR) determined by means semiquantitative reverse transcription-polymerase chain reaction. Notably, the...

Endothelin-converting enzyme (ECE) is a membrane metalloprotease that generates endothelin from its direct precursor big endothelin. Four isoforms of ECE-1 are produced single gene through the use alternate promoters. These share same extracellular catalytic domain and contain unique cytosolic tails, which results in their specific subcellular targeting. We investigated distribution transfected AtT-20 neuroendocrine cells. Whereas ECE-1a 1c were present at plasma membrane, ECE-1b ECE-1d...

Ovarian granulosa cells from small follicles have generally been considered to comprise a homogeneous cell population; however, stratified arrangements of hormone receptors found in antral and mural Graafian follicles. Using cultured derived immature, hypophysectomized, estrogen-treated rats, we previously shown that vasoactive intestinal peptide (VIP) as well FSH stimulates steroid production by these cells. Dose-response analysis indicated the actions hormones were additive, suggesting...

The pattern and regulation of endothlin-2 (EDN2) expression its putative roles in bovine ovaries were investigated. EDN2 mRNA was determined corpus luteum (CL) during folliculoluteal transition induced by GnRH vivo. elevated only the early CL not present older CL. In young CL, identified mainly luteal cells but endothelial that expressed EDN1 gene. Similarly, preovulatory follicles, granulosa (GCs) vascular theca interna. LH hypoxia are two major stimulants formation. Therefore, GCs cultured...