scholarly journals Hormonal and Nutritional Stretegies to Optimize Reproductive Function and Improve Fertility of Dairy Cattle during Heat Stress in Summer

1994 ◽  
Author(s):  
David Wolfenson ◽  
William W. Thatcher ◽  
Rina Meidan ◽  
Charles R. Staples ◽  
Israel Flamenbaum
Keyword(s):  
Heat Stress ◽  
Pregnancy Rate ◽  
Granulosa Cells ◽  
Gnrh Agonist ◽  
Follicular Development ◽  
Low Fertility ◽  
Small Scale ◽  
Plasma Progesterone ◽  
Theca Cells ◽  
Days Open

The BARD program includes two main parts. In the first, experiments were conducted to complete our understanding of the mechanisms responsible for the impairment of reproductive functions under heat stress. Experiments focused on follicular development and function, since results obtained in our previous BARD project indicate that the preovulatory follicle is susceptible to heat stress. The theca cells, sensitive to thermal stress, produced less androgen during the summer, as well as during the autumn. Similarly, luteinized theca cells obtained from cows in summer produced much less progesterone than in winter. Granulosa cells and luteinized granulosa cells were less susceptible to heat stress. A delayed effect of heat stress on follicular development, on suppression of dominance and on steroid production by theca and granulosa cells was noted. This may be related to the low fertility of cows during the cool months of autumn. In the second part, experiments were conducted aiming to improve fertility in summer. The timed AI program was developed using two injections of GnRH coupled with PGF2a. It was found effective in improving reproductive performance in lactating cows. Limitations induced by heat stress on estrus detection were eliminated with the timed AI management program. Replacing the second injection of GnRH with hCG instead of GnRH agonist increased plasma progesterone levels post ovulation but did not improve fertility. Use of the timed AI program in summer, shortened days open and increased the net revenue per cow, however, it did not protect the embryo fiom temperature-induced embryonic mortality. Incorporation of a GnRH-agonist implant into the timed AJ program was examined. The implant increased plasma progesterone and LH concentrations and altered follicular dynamics. The use of a GnRH-implant enhanced pregnancy rate in cows with low body conditions. In a timed embryo transfer experiment, the use of fresh or frozen in vitro produced embryos was compared in the summer to improve fertility. The use of flesh embryos (but not frozen ones) improved pregnancy rate, however, substantial embryonic death occurred between 21 and 45 days. The timed AI program, which is now being used commercially, shortened days open, and increased pregnancy rate during summer. Other approaches which were found to improve fertility in small-scale studies, need to be tested again in large-scale field trials.

scholarly journals Heat stress diminishes gonadotropin receptor expression and enhances susceptibility to apoptosis of rat granulosa cells

Reproduction ◽  
2005 ◽  
Vol 129 (4) ◽  
pp. 463-472 ◽  
Author(s):  
Takashi Shimizu ◽  
Izumi Ohshima ◽  
Manabu Ozawa ◽  
Satoko Takahashi ◽  
Atsushi Tajima ◽  
...  
Keyword(s):  
Heat Stress ◽  
Granulosa Cells ◽  
Follicular Fluid ◽  
Follicular Development ◽  
Receptor Expression ◽  
Female Rats ◽  
Aromatase Activity ◽  
Mrna Levels ◽  
Gonadotropin Receptor ◽  
Estradiol Levels

Heat stress inhibits ovarian follicular development in mammalian species. We hypothesized that heat stress inhibits the function of follicular granulosa cells and suppresses follicular development. To test this, immature female rats were injected with pregnant mare serum gonadotropin (PMSG) at 48 h after the start of temperature treatment (control: 25 °C, 50% RH; heat stress: 35 °C, 70% Relative Humidity). The ovaries and granulosa cells of follicles at different developmental stages were analyzed for gonadotropin receptor levels and aromatase activity; estradiol levels were measured in follicular fluid. Before injection, heat stress diminished only the amount of FSH receptor on granulosa cells of antral follicles. During PMSG-stimulated follicular development, heat stress strongly inhibited gonadotropin receptor levels and aromatase activity in granulosa cells, and estradiol levels in the follicular fluid of early antral, antral and preovulatory follicles. To examine apoptosis and mRNA levels of bcl-2 and bax in granulosa cells, follicles harvested 48 h after PMSG injection were cultured in serum-free conditions. Heat-stressed granulosa cells showed a time-dependent increase in apoptosis. The bcl-2 mRNA levels were similar in control and heat-stressed granulosa cells; bax mRNA levels were increased in heat-stressed granulosa cells. According to these results, heat stress inhibits expression of gonadotropin receptors in granulosa cells and attenuates estrogenic activity of growing follicles, granulosa cells of heat-stressed follicles are susceptible to apoptosis, and the bcl2/bax system is not associated with heat-stress-induced apoptosis of granulosa cells. Our study suggests that decreased numbers and function of granulosa cells may cause ovarian dysfunction in domestic animals in summer.

scholarly journals Delayed effect of heat stress on steroid production in medium-sized and preovulatory bovine follicles

Reproduction ◽  
2001 ◽  
pp. 745-751 ◽  
Author(s):  
Z Roth ◽  
R Meidan ◽  
A Shaham-Albalancy ◽  
R Braw-Tal ◽  
D Wolfenson
Keyword(s):  
Heat Stress ◽  
Granulosa Cells ◽  
Follicular Fluid ◽  
Heat Exposure ◽  
Low Fertility ◽  
Delayed Effect ◽  
Steroid Production ◽  
Thecal Cells ◽  
Preovulatory Follicles ◽  
Subsequent Cycle

During the autumn, the 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 of heat stress on cattle fertility. Two experiments were conducted to examine possible delayed effects of heat stress on follicular characteristics and steroid production at two distinct stages of follicular growth: medium-sized and preovulatory follicles, 20 and 26 days after heat exposure, respectively. Lactating cows were subjected to heat stress for 12 h a day in an environmental chamber, during days 2-6 of a synchronized oestrous cycle. In Expt 1, ovaries were collected on day 3 of the subsequent cycle, before selection of the dominant follicle, and medium-sized follicles were classified as atretic or healthy. In Expt 2, on day 7 of the subsequent cycle, PGF(2a) was administered and preovulatory follicles were collected 40 h later. In both experiments, follicular fluid was aspirated, granulosa and thecal cells were incubated, and steroid production was determined. In healthy medium-sized follicles (Expt 1), oestradiol production by granulosa cells and androstenedione production by thecal cells were lower (P < 0.05) and the concentration of progesterone in the follicular fluid was higher in cows that had been previously heat-stressed than in control cows (P < 0.05). In preovulatory follicles (Expt 2), the viability of granulosa cells was lower (P < 0.05) and the concentration of androstenedione in the follicular fluid and its production by thecal cells were lower (P < 0.05) in cows that had been previously heat-stressed than in control cows. In both experiments, the oestradiol concentrations in the follicular fluids were not altered by heat stress. These results demonstrate a delayed effect of heat stress on steroid production and follicular characteristics in both medium-sized and preovulatory follicles; this effect could be related to the low fertility of cattle in the autumn.

scholarly journals Localization of gonadotrophin-releasing hormone I, bradykinin and their receptors in the ovaries of non-mammalian vertebrates

Reproduction ◽  
2007 ◽  
Vol 133 (5) ◽  
pp. 969-981 ◽  
Author(s):  
Padmasana Singh ◽  
Amitabh Krishna ◽  
Rajagopala Sridaran
Keyword(s):  
Granulosa Cells ◽  
Follicular Development ◽  
Cell Types ◽  
Physiological Significance ◽  
Rt Pcr ◽  
Releasing Hormone ◽  
Theca Cells ◽  
Gonadotrophin Releasing Hormone

GnRH I and its receptors have been demonstrated in the ovaries of various vertebrates, but their physiological significance in reproductive cascade is fragmentary. Bradykinin is a potent GnRH stimulator in the hypothalamus. In the present study, the presence of GnRH I and its receptor, and bradykinin and its receptor in the ovaries of non-mammalian vertebrates were investigated to understand their physiological significance. GnRH I immunoreactivity in the ovaries of fish, frog, reptile and bird were mainly found in the oocyte of early growing follicles and granulosa cells and theca cells of previtellogenic follicles. Vitellogenic follicles showed mild GnRH immunoreactivity. GnRH I-receptor and bradykinin were localized in the same cell types of the ovaries of these vertebrates. The presence of GnRH I, GnRH I-receptor and bradykinin in the ovaries of these vertebrates was confirmed by immunoblotting. The presence of GnRH I mRNA was demonstrated in the ovary of vertebrates using RT-PCR. The ovaries of reptiles and birds showed significantly higher intensity of immunoreactivity for GnRH I-receptor as compared with the fish and amphibian. This may have a correlation with the higher yolk content in the ovary of reptile and bird. These results suggest the possibility of GnRH I and bradykinin as important regulators of follicular development and vitellogenesis in the vertebrate ovary.

scholarly journals Expression and effect of NAMPT (visfatin) on progesterone secretion in hen granulosa cells

Reproduction ◽  
2015 ◽  
Vol 150 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Mélodie Diot ◽  
Maxime Reverchon ◽  
Christelle Ramé ◽  
Yannick Baumard ◽  
Joëlle Dupont
Keyword(s):  
Granulosa Cells ◽  
Specific Inhibitor ◽  
Follicular Development ◽  
Rt Pcr ◽  
Nicotinamide Phosphoribosyltransferase ◽  
Theca Cells ◽  
Protein Levels ◽  
Progesterone Secretion ◽  
Ovulatory Follicles

In mammals, nicotinamide phosphoribosyltransferase (NAMPT) is an adipokine produced by adipose tissue that is found in intracellular and extracellular compartments. The intracellular form of NAMPT is a nicotinamide phosphoribosyltransferase, whereas the extracellular form is considered an adipokine. In humans, NAMPT regulates energy metabolism and reproductive functions, such as ovarian steroidogenesis. To date, no study has investigated the role of NAMPT in hen ovaries. We investigated whether NAMPT is present in hen ovarian follicles and its role in granulosa cells. Using RT-PCR, western blotting and immunocytochemistry, we detected mRNA transcripts and proteins related to NAMPT in theca and granulosa cells from pre-ovulatory follicles. Using RT-PCR, we demonstrated that mRNA NAMPT levels were higher in granulosa cells than they were in theca cells and that during follicle development, theca cell levels decreased, whereas levels remained unchanged in granulosa cells. NAMPT protein quantities were significantly higher in theca cells than they were in granulosa cells, but they were unchanged during follicular development. Plasma NAMPT levels, as determined by ELISA and immunoblotting, were significantly lower in adult hens than they were in juveniles. In vitro, treatment with human recombinant NAMPT (100 ng/ml, 48 h) halved basal and IGF1-induced progesterone secretion, and this was associated with a reduction in STAR and HSD3B protein levels and MAPK3/1 phosphorylation levels in granulosa cells. These effects were abolished by the addition of FK866, a specific inhibitor of NAMPT enzymatic activity. Moreover, NAMPT had no effect on granulosa cell proliferation. In conclusion, NAMPT is present in hen ovarian cells and inhibits progesterone production in granulosa cells.

Immunohistochemical localization of steroidogenic enzymes and comparison with hormone production during follicle development in the pig

1999 ◽  
Vol 11 (6) ◽  
pp. 337 ◽  
Author(s):  
Ellen M. Shores ◽  
Morag G. Hunter
Keyword(s):  
Granulosa Cells ◽  
Follicular Development ◽  
Staining Intensity ◽  
Immunohistochemical Localization ◽  
Vital Role ◽  
Steroidogenic Enzymes ◽  
Hormone Production ◽  
Theca Cells ◽  
Enzyme Distribution ◽  
Follicle Size

The steroidogenic enzymes, P450 aromatase (P450 arom ) and P450 17a-hydroxylase (P450 17a ), were precisely located within the healthy porcine follicle by immunohistochemistry. Enzyme distribution was examined throughout follicular development during natural oestrous cycles (n = 14 gilts) and was compared with steroid production by healthy whole and theca-only follicles. All follicles 2 mm or more in diameter were either fixed for immunohistochemistry (n = 380 of which 197 were assessed as healthy) or incubated as whole (n = 110) or theca-only (n = 110) follicles to measure steroidogenesis. P450 17a was confined to the theca layer. The number of positive cells and staining intensity increased with follicle size. P450 arom was consistently detected in the granulosa layer of follicles measuring 6 mm or more in diameter and those cells furthest from the antrum were most strongly stained. P450arom was also detected in the theca layer of these large follicles. Whole and theca-only follicles produced oestradiol and androstenedione, and the levels of both hormones increased with follicle size (P<0.001). Whole follicles produced more oestradiol (P<0.001), but less androstenedione (P = 0.01) than theca-only follicles of the same size. Although granulosa cells contained P450 arom and synthesized oestradiol, only theca cells contained P450 17a. Theca cells therefore provided granulosa cells with androgen substrate. In addition, theca cells possessed P450 arom , making them capable of independent oestradiol production, which may be required to trigger the LH surge. This study confirms the vital role of theca cells in follicular steroidogenesis in the pig.

Immediate and delayed effects of heat stress on follicular development and its association with plasma FSH and inhibin concentration in cows

Reproduction ◽  
2000 ◽  
pp. 83-90 ◽  
Author(s):  
Z Roth ◽  
R Meidan ◽  
R Braw-Tal ◽  
D Wolfenson
Keyword(s):  
Heat Stress ◽  
Follicular Development ◽  
Oestrous Cycle ◽  
Low Fertility ◽  
Delayed Effect ◽  
Delayed Effects ◽  
Treatment Groups ◽  
Follicular Wave ◽  
Subsequent Cycle ◽  
Follicular Dynamics

The aim of this study was to characterize the immediate effects of heat stress on plasma FSH and inhibin concentrations, and its involvement in follicular dynamics during a complete oestrous cycle, and to examine a possible delayed effect of heat stress on follicular development. Holstein dairy cows were oestrous synchronized and randomly assigned to either cooled (n = 7) or heat-stressed (n = 6) treatment groups. During a complete oestrous cycle, control cows, which were cooled, maintained normothermia, whereas heat-stressed cows, which were exposed to direct solar radiation, developed hyperthermia. At the end of this oestrous cycle (treated cycle), both groups were cooled and maintained normothermia for the first 10 days of the subsequent oestrous cycle. Throughout this period, follicular development was examined by ultrasonography, and plasma samples were collected. During the second follicular wave of the treated oestrous cycle, a significantly larger cohort of medium sized follicles (6-9 mm) was found in heat-stressed cows than in cooled cows (P < 0.05). The enhanced growth of follicles in this wave in heat-stressed cows was associated with a higher plasma FSH increase which lasted 4 more days (days 8-13 of the oestrous cycle; P < 0.05), and coincided with a decrease in the plasma concentration of immunoreactive inhibin (days 5-18 of the oestrous cycle; P < 0.05). During the follicular phase (days 17-20 of the treated cycle), heat-stressed cows showed an increase in the number of large follicles (>/= 10 mm), and the preovulatory plasma FSH surge was significantly higher in heat-stressed cows than in cooled cows (P < 0.01). The effect of heat stress was also observed during the first follicular wave of the subsequent cycle: the postovulatory plasma FSH concentration was higher (P < 0.01), but fewer medium follicles developed, and the first follicular wave decreased at a slower rate in previously heat-stressed cows than in cooled cows (0.40 and 0.71 follicles per day, respectively). This study shows both immediate and delayed effects of heat stress on follicular dynamics, which were associated with high FSH and low inhibin concentrations in plasma. These alterations may have physiological significance that could be associated with low fertility of cattle during the summer and autumn.

scholarly journals Regulation of expression of ovarian mRNA encoding steroidogenic enzymes and gonadotrophin receptors by FSH and GH in hypogonadotrophic cattle

Reproduction ◽  
2002 ◽  
pp. 651-661 ◽  
Author(s):  
HA Garverick ◽  
G Baxter ◽  
J Gong ◽  
DG Armstrong ◽  
BK Campbell ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Granulosa Cells ◽  
Gnrh Agonist ◽  
Follicular Growth ◽  
Steroidogenic Enzymes ◽  
Lh Receptor ◽  
Theca Cells ◽  
Follicular Wave ◽  
Follicle Size ◽  
Bovine Somatotrophin

A study was conducted to determine the effects of FSH and bovine somatotrophin on the expression of mRNA encoding the gonadotrophin receptors and steroidogenic enzymes in ovarian follicles of cattle rendered hypogonadotrophic by treatment with a GnRH agonist. Hereford x Friesian heifers were allotted into two pretreatment groups: controls (n = 10) and GnRH agonist-treated (n = 20). Ovaries of control cows were removed on day 2 of the first follicular wave after synchronized oestrus. GnRH agonist-treated heifers were given either FSH or no FSH. FSH was infused at 50 microg h(-1) for 48 h. Ovaries in GnRH agonist-treated heifers were removed at the end of exogenous hormone treatment. The control, GnRH agonist and GnRH agonist plus FSH treatment groups were divided further into bovine somatotrophin or no bovine somatotrophin treatments (n = 5 per treatment). Bovine somatotrophin (25 mg day(-1) by s.c. injection) was administered for 3 days. Ovaries were scanned once a day by ultrasonography. Blood samples for hormone measurements were collected three times a day from oestrus until the time of removal of ovaries. Expression of mRNAs for the FSH and LH receptors and cytochrome P450 side-chain cleavage (P450scc), cytochrome P450 17alpha-hydroxylase (P450c17) and cytochrome P450 aromatase (P450arom) enzymes was localized by in situ hybridization and quantified by image analysis. Ovarian follicular growth was arrested at < or = 4.5 mm in diameter in GnRH agonist-treated heifers. There was no effect of bovine somatotrophin on follicular dynamics, gonadotrophin secretion or expression of mRNA for either the gonadotrophin receptors or steroidogenic enzymes. Infusion of FSH to GnRH agonist-treated heifers increased FSH concentrations in serum to the physiological concentrations observed in controls and stimulated growth of follicles to a size similar (5.5-8.0 mm in diameter) to recruited follicles in control cows. FSH induced mRNA expression of P450scc and P450arom in granulosa cells of follicles at a smaller size (< or = 4.5 mm in diameter) than in controls and increased (P < 0.001) expression in larger (> 4.5 mm in diameter) follicles. Expression of mRNAs for P450scc and P450c17 increased (P < 0.001) with increasing follicle size and was higher (P < 0.01) in theca cells of GnRH agonist plus FSH-treated heifers than in the other groups. There were no treatment differences in expression of FSH receptor in granulosa cells or LH receptor in theca cells, but expression of both receptors increased with follicle size. There was no expression of LH receptor in the granulosa cells of cows from any treatment group. In conclusion, FSH treatment in GnRH agonist-treated heifers induced similar changes in follicular growth to those observed during the first follicular wave, but despite similar peak concentrations, prolonged exposure to high FSH induced precocious expression of mRNAs for P450scc and P450arom in granulosa cells from small follicles and markedly upregulated expression of these enzymes in granulosa cells from recruited follicles. The results of this study demonstrate the key role that FSH plays in the induction of follicular growth and differentiation.

scholarly journals The hedgehog-patched signaling pathway and function in the mammalian ovary: a novel role for hedgehog proteins in stimulating proliferation and steroidogenesis of theca cells

Reproduction ◽  
2009 ◽  
Vol 138 (2) ◽  
pp. 329-339 ◽  
Author(s):  
Leon J Spicer ◽  
Satoko Sudo ◽  
Pauline Y Aad ◽  
Lora Shuo Wang ◽  
Sang-Young Chun ◽  
...  
Keyword(s):  
Granulosa Cells ◽  
Follicular Development ◽  
Mrna Abundance ◽  
Rt Pcr ◽  
Theca Cells ◽  
Qrt Pcr ◽  
Hedgehog Proteins ◽  
Patched 1 ◽  
And Function ◽  
First Time

The expression of hedgehog (Hh) genes, their receptor, and the co-receptor in mice, rat, and bovine ovaries were investigated. RT-PCR of ovarian transcripts in mice showed amplification of transcripts for Indian (Ihh) and desert (Dhh) Hh, patched 1 (Ptch1), and smoothened (Smo) genes. Semi-quantitative RT-PCR and northern blot analyses showed that whole ovarianIhhandDhhtranscripts decreased 4–24 h after hCG versus 0–48 h after pregnant mares serum gonadotrophin treatment in mice, whereas mousePtch1andSmotranscripts were expressed throughout the gonadotropin treatments. Quantitative real-time RT-PCR (qRT-PCR) revealed that the expression of the Hh-patched signaling system withIhhmRNA abundance in granulosa cells was greater, whereasSmoandPtch1mRNA abundance was less in theca cells of small versus large follicles of cattle. In cultured rat and bovine theca-interstitial cells, qRT-PCR analyses revealed that the abundance ofGli1andPtch1mRNAs were increased (P<0.05) with sonic hedgehog (SHH) treatment. Additional studies using cultured bovine theca cells indicated that SHH induces proliferation and androstenedione production. IGF1 decreasedIhhmRNA abundance in bovine granulosa cells. The expression and regulation ofIhhtranscripts in granulosa cells andPtch1mRNA in theca cells suggest a potential paracrine role of this system in bovine follicular development. This study illustrates for the first time Hh activation of Gli1 transcriptional factor in theca cells and its stimulation of theca cell proliferation and androgen biosynthesis.

scholarly journals Early Follicular Development and Atretic Changes in the Ovary of the Lamb? Fine Structure and Histochemistry

1980 ◽  
Vol 33 (6) ◽  
pp. 675 ◽  
Author(s):  
Robin Tassell ◽  
JP Kennedy
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Protein Secretion ◽  
Granulosa Cells ◽  
Zona Pellucida ◽  
Smooth Endoplasmic Reticulum ◽  
Follicular Development ◽  
Primordial Follicles ◽  
Theca Cells ◽  
Pregnant Mare Serum Gonadotrophin

The fine structure of follicles was studied in ovaries from lambs up to 32 days old. Some animals received pregnant mare serum gonadotrophin prior to sampling. Follicles examined were in the primordial to early antral stages. The oocyte is described and changes associated with its development and the formation of the zona pellucida are recorded. Characteristics in which the lamb oocyte differed from those of other mammals included a greater prominence of smooth endoplasmic reticulum, the presence of microtubules, fine filaments in the peripheral parts and a large number of almost empty vacuoles. The latter were more numerous in oocytes which appeared to be degenerating, including some of those in primordial follicles. Granulosa cells had characteristics usually associated with protein secretion while some theca cells had large amounts of endoplasmic reticulum bearing few ribosomes. In early atresia changes were evident successively in the oocyte, granulosa and theca.

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