scholarly journals Histomorphometric and immunohistochemical changes in interstitial cells and ovarian follicles of rats treated with metformin during and after induction of permanent estrus

2021 ◽  
Vol 10 (6) ◽  
pp. e5110615536
Author(s):  
Leonardo Augusto Lombardi ◽  
Leandro Sabará Mattos ◽  
Marcio Luis Alves Moura ◽  
Ana Paula Espindula ◽  
Ricardo Santos Simões ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Granulosa Cells ◽  
Caspase 3 ◽  
Ovarian Follicles ◽  
Interstitial Cells ◽  
Nuclear Volume ◽  
Female Rats ◽  
Continuous Illumination ◽  
Ovarian Cysts ◽  
Significant Difference

Objective: To evaluate the histomorphometric and immunohistochemical changes in interstitial cells and ovarian follicles of rats treated with metformin during and after induction of permanent estrus. Methods: Thirty-two adult-female rats with regular estrous cycle were equally divided into four groups: 1) GCtrl - at estrous phase. 2) GPCOS - at permanent-estrous phase. 3) GMet1 - rats and daily treated with metformin (12.5 mg/Kg) during 60 consecutive days, as preventive form and 4) GMet2 - PCOS rats, which remained exposed to 60 days of continuous illumination and treated with metformin. After that, the animals were euthanized, and the ovaries were removed and processed for paraffin embedding. Sections were stained with H.E. for histomorphometry or subjected to immunohistochemistry for Ki-67 and cleaved caspase-3 (Casp-3) detections. Results: The GPCOS showed lack of corpus luteum and several ovarian cysts, as well as interstitial-like cells. The presence of corpus luteum and a significant increase in primary and antral follicles were observed in Mel-treated groups, which also showed a decrease in the number of ovarian cysts and in the area occupied by interstitial-like cells. The presence of corpus luteum along with an increase in the number of primary follicles in the Met2 group were noticed (p<0,01). A significant reduction in number of cysts and in the area occupied by interstitial cells, as well as a decrease in nuclear volume of interstitial cells, were noticed in the Met-treated groups, mainly in the Met2 group. The percentage of cell proliferation was significantly higher in granulosa cells of the Met-treated groups than PCOS group, mainly in the GMet2 (p<0,01), which was similar to the GCtrl group. On the other hand, the percentage of apoptosis (cleaved-caspase-3- positive cells) was significantly higher in the granulosa cells of GPCOS and Met-treated groups than the GCtrl group, but without significant difference, which showed weak cleaved caspase-3 immunoreactivity in those cells. Conclusion: The ovaries of rats treated with metformin showed a decrease in nuclear volume and in the area occupied by interstitial cells, presence of corpus luteum, in addition to a decrease in the number of cysts.

scholarly journals Immunohistochemical evaluation of proliferation, apoptosis and steroidogenic enzymes in the ovary of rats with polycystic ovary

2014 ◽  
Vol 60 (4) ◽  
pp. 349-356 ◽  
Author(s):  
Leonardo Augusto Lombardi ◽  
Ricardo Santos Simões ◽  
Carla Cristina Maganhin ◽  
Maria Cândida Pinheiro Baracat ◽  
Gisela Rodrigues Silva-Sasso ◽  
...  
Keyword(s):  
Granulosa Cells ◽  
Caspase 3 ◽  
Polycystic Ovary ◽  
Interstitial Cells ◽  
Ovarian Cysts ◽  
Polycystic Ovaries ◽  
Ki 67 ◽  
Pcos Group ◽  
Theca Interna ◽  
Enzyme Markers

Objective: to evaluate the immunohistochemical expression of proliferative, apoptotic and steroidogenic enzyme markers in the ovaries of rats with polycystic ovary syndrome (PCOS). Methods: twenty rats were divided into two groups: GCtrl - estrous phase, and PCOS - with polycystic ovaries. The GCtrl animals were subjected to a lighting period from 7 am to 7 pm, while the animals with PCOS group remained with continuous lighting for 60 days. Subsequently, the animals were anesthetized, the ovaries were removed and fixed in 10% formaldehyde, prior to paraffin embedding. Sections were stained using H.E. or subjected to immunohistochemical methods for the detection of Ki-67, cleaved caspase-3, CYP11A1, CYP17A1 and CYP19A1. The results were analyzed using Student's t-test (p < 0,05). Results: morphological results showed evidence of interstitial cells originating from the inner theca cells of degenerating ovarian cysts in PCOS. Immunoexpression of Ki-67 was higher in the granulosa cells in GCtrl, and the theca interna cells in PCOS, while cleaved caspase-3 was higher in granulosa cells of ovarian cysts from PCOS and in the theca interna cells of GCtrl. Immunoreactivity of CYP11A1 in the theca interna, granulosa and interstitial cells was similar between the two groups, while CYP17A1 and CYP19A1 were higher in the granulosa and interstitial cells in the PCOS group. Conclusion: the results indicate that the interstitial cells are derived from the theca interna and that enzymatic changes occur in the theca interna and interstitial cells in ovaries of rats with PCOS, responsible for the high levels of androgens and estradiol.

Indomethacin treatment prevents prolactin-induced luteolysis in the rat

1987 ◽  
Vol 112 (2) ◽  
pp. 317-322 ◽  
Author(s):  
J. E. Sánchez-Criado ◽  
K. Ochiai ◽  
I. Rothchild
Keyword(s):  
Corpus Luteum ◽  
Left Kidney ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Silicone Elastomer ◽  
Serum Prolactin ◽  
Corpora Lutea ◽  
Synthesis Inhibitor ◽  
Significant Difference ◽  
Indomethacin Treatment

ABSTRACT Adult female rats were hypophysectomized and their pituitary glands autotransplanted beneath the left kidney capsule on day 2 (day 1 was the day of ovulation). In such rats the pituitary secretes prolactin fairly constantly and the corpora lutea secrete progesterone for several months. To induce the luteolytic effect of prolactin the rats were first injected s.c. with 2-bromo-α-ergocryptine (CB-154) on cycle days 12, 13 and 14 (i.e. 10, 11 and 12 days after operation) to depress prolactin secretion, and then with CB-154 vehicle (70% ethanol) daily until cycle day 21, to allow prolactin secretion to resume. One ovary was removed from each rat on day 15 and the remaining one on day 22. The mean (± s.e.m.) weight of the corpora lutea on day 15 was 1·46±0·06 mg and 0·98±0·07 mg on day 22 (n = 17). In contrast, rats in which the CB-154 treatment was maintained to day 21 had corpora lutea which weighed 1·31 ±0·09 on day 15 and 1·47 ±0·08 mg on day 22 (n = 15). To investigate whether indomethacin, a prostaglandin synthesis inhibitor, affected the luteolytic action of prolactin, the experiment was repeated, but on day 15 (after the removal of one ovary) the groups in which CB-154 treatment was stopped, as well as the group in which CB-154 treatment was maintained, were each divided into two groups. In one, indomethacin-containing silicone elastomer wafers and, in the other, blank silicone elastomer wafers, were placed within the bursa of the remaining ovary. There were no differences in corpus luteum weight on day 15 among any of these groups and the two groups of the first experiment. There was no significant difference in corpus luteum weight between day 15 and day 22 in any of the six groups except for the two groups treated with the CB-154 vehicle and not with indomethacin. Thus, treatment with indomethacin prevented the fall in corpus luteum weight associated with the discontinuation of CB-154 treatment. Serum prolactin levels fell until day 15 in all rats and remained low in those in which the CB-154 treatment was maintained to day 21, but returned to control values in those treated with vehicle after day 14. Serum progesterone levels fell and remained low in all groups. Indomethacin treatment had no effect on the levels of either serum prolactin or progesterone. We conclude that some of the pharmacological effects of indomethacin are to prevent prolactin-induced luteolysis, and we suggest that prolactin induces rapid regression of the corpus luteum by stimulating intraluteal prostaglandin production or by being necessary for the effect of luteolytic prostaglandins. J. Endocr. (1987) 112, 317–322

scholarly journals Targeted disruption of the aromatase P450 gene (Cyp19) in mice and their ovarian and uterine responses to 17beta-oestradiol

2001 ◽  
Vol 170 (1) ◽  
pp. 99-111 ◽  
Author(s):  
K Toda ◽  
K Takeda ◽  
T Okada ◽  
S Akira ◽  
T Saibara ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Corpus Luteum ◽  
Lipid Droplets ◽  
Smooth Endoplasmic Reticulum ◽  
Ovarian Follicles ◽  
Interstitial Cells ◽  
Aromatase Activity ◽  
Tubular Structures ◽  
Wild Type ◽  
Targeted Disruption

Aromatase P450 (CYP19) is an enzyme catalysing the conversion of androgens into oestrogens. We generated mice lacking aromatase activity (ArKO) by targeted disruption of Cyp19 and report the characteristic features of the ArKO ovaries and uteri as revealed by histological and biochemical analyses. ArKO females were totally infertile but there were as many developing follicles in their ovaries at 8 weeks of age as in wild-type ovaries. Nevertheless, no typical corpus luteum was observed in the ArKO ovaries. Electron microscopy revealed the presence of well-developed smooth endoplasmic reticulum, few lipid droplets and mitochondria with less organized tubular structures in the ArKO luteinized interstitial cells. These ultrastructural features were different from those of the wild-type interstitial cells, where there are many lipid droplets and mitochondria with well-developed tubular structures, characteristic of steroid-producing cells. When ArKO mice were supplemented with 17beta-oestradiol (E(2); 15 microg/mouse) every fourth day from 4 weeks of age for 1 month, increased numbers of follicles were observed in the ovaries as compared with those of untreated ArKO mice, although no typical corpus luteum was detectable. Ultrastructural analysis revealed the disappearance of the accumulated smooth endoplasmic reticulum in the luteinized interstitial cells after E(2 )supplementation. Transcripts of pro-apoptotic genes such as p53 and Bax genes were markedly elevated in the ArKO ovaries as compared with those of wild-type mice. Although E(2) supplementation did not cause suppression of the elevated expression of p53 and Bax mRNAs, it caused marked enhancement of expression levels of lactoferrin and progesterone receptor mRNAs in the uteri as well as increases in uterine wet weight. At 8 months of age, ArKO mice developed haemorrhages in the ovaries, in which follicles were nearly depleted, while age-matched wild-type females still had many ovarian follicles. Furthermore, macrophage-like cells were occasionally observed in the ArKO ovarian follicles. These results suggested that targeted disruption of Cyp19 caused anovulation and precocious depletion of ovarian follicles. Additionally, analysis of mice supplemented with E(2) demonstrated that E(2) apparently supports development of ovarian follicles, although it did not restore the defect in ovulation.

scholarly journals Implication of cortisol and 11β-hydroxysteroid dehydrogenase enzymes in the development of porcine (Sus scrofa domestica) ovarian follicles and cysts

Reproduction ◽  
2007 ◽  
Vol 133 (6) ◽  
pp. 1149-1158 ◽  
Author(s):  
Neera Sunak ◽  
Daphne F Green ◽  
Lalantha R Abeydeera ◽  
Lisa M Thurston ◽  
Anthony E Michael
Keyword(s):  
Granulosa Cells ◽  
Hydroxysteroid Dehydrogenase ◽  
Ovarian Follicles ◽  
Cyst Fluid ◽  
Ovarian Cysts ◽  
Follicle Growth ◽  
Antral Follicles ◽  
Cortisol Metabolism ◽  
Porcine Granulosa Cells ◽  
Follicle Diameter

This study investigated cortisol inactivation by 11β-hydroxysteroid dehydrogenase (11β HSD) enzymes in porcine granulosa cells from antral follicles at different developmental stages and in ovarian cysts. In granulosa cells, cortisol oxidation increased threefold with antral follicle diameter (P < 0.001). This trend was paralleled by a threefold increase in NADP+-dependent 11β-dehydrogenase activity in granulosa cell homogenates with follicle diameter. Intact granulosa cells from ovarian cysts exhibited significantly lower enzyme activities than cells from large antral follicles. Neither intact cells norcell homogenates displayed net 11-ketosteroid reductase activities. Since porcine follicular fluid (FF) from large antral follicles and ovarian cysts contains hydrophobic inhibitors of glucocorticoid metabolism by type 1 11β HSD, this studyalso investigated whether levels of 11β HSD inhibitors changed during follicle growth and could affect cortisol metabolism in granulosa cells. The extent of inhibition of 11β HSD1 activity in rat kidney homogenates decreased progressively from 50 ± 8% inhibition by FF from small antral follicles (P < 0.001) to 23 ± 6% by large antral FF (P < 0.05). Cyst fluid inhibited 11β HSD1 activity by 59 ± 4% (P < 0.001). Likewise, net cortisol oxidation in granulosa cells was significantly decreased by large antral FF (35–48% inhibition, P < 0.05) and cyst fluid (45–75% inhibition, P < 0.01). We conclude that inactivation of cortisol by 11β HSD enzymes in porcine granulosa cells increases with follicle development but is significantly decreased in ovarian cysts. Moreover, changes in ovarian cortisol metabolism are accompanied by corresponding changes in the levels of paracrine inhibitors of 11β HSD1 within growing ovarian follicles and cysts, implicating cortisol in follicle growth and cyst development.

scholarly journals ACTIVITY AND CONTENT OF SUPEROXIDEDISMUTASE IZOZYMES IN GRANULOSE CELLS FROM COW OVARY FOLLICLES

2020 ◽  
Vol 21 (2) ◽  
pp. 33-39
Author(s):  
Yu. V. Bodnar ◽  
N. V. Kuzmina ◽  
D. D. Ostapiv ◽  
S. W. Kawa ◽  
O. I. Chajkovska ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Corpus Luteum ◽  
Granulosa Cells ◽  
Follicular Fluid ◽  
Physiological State ◽  
Ovarian Follicles ◽  
Extracellular Proteins ◽  
Cytotoxic Action ◽  
Follicular Growth ◽  
Sod Activity

The activity and content of superoxide dismutase isoforms (SOD) in granulosa cells from cow ovarian follicles were studied for research after slaughter of cows ovaries were selected, which according to the physiological state were divided into groups: with "fresh" ovulation, at the site of the ovulated follicle there is a hole, no corpus luteum or diameter up to 5 mm, red color (n = 14); with "early corpus luteum", diameter 10-20 mm, color red or brown (n = 41); with “late corpus luteum", diameter 5–15 mm, color yellow (n = 32); "follicular growth", without the corpus luteum (n = 84). The ovaries of cows with small (<4 mm), medium (4 - 7 mm) and large (> 7 mm) follicles were used. Antral fluid was obtained from the follicles, from which granulosa cells were isolated. Cells were suspended according to the volume of follicular fluid in the medium Dulbeccos modified Eagle medium (DME) with the addition of estrus serum of cows, follicular fluid, insulin and heparin. In cell culture, protein concentration, activity, and superoxide dismutase isozymes were determined. It was found that granulosa cells are characterized by SOD activity - 12.4 ± 0.74 IU / mg protein (6.8 ± 1.72 - 19.8 ± 3.75 IU / mg protein). The activity of SOD in the culture of granulosa cells had 5–6 isoforms of the enzyme. It was found that isoforms at the site of localization are divided into cytosolic, mitochondrial and extracellular proteins of SOD. The cytosolic isoform were represented by 3 - 4, and mitochondrial and extracellular have one active protein of the enzyme. he activity of the enzyme and the content of isoforms depended on the size of the follicles from which the cells are removed and the physiological state of the ovaries. The studied indicators characterize the intensity of oxidative metabolism as a whole in cells and in their individual parts and organelles. For cultivation, it is advisable to select granulosa cells from ovarian follicles of "follicular growth" and "late corpus luteum" because they are characterized by consistently high activity of SOD, which protects intracellular components from the cytotoxic action of superoxide anion.

Immunohistochemical localization of inhibin α- and βA-subunits in the ovary of immature female rats

1995 ◽  
Vol 132 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Mitsuko Kobayashi ◽  
Mareo Yamoto ◽  
Sawako Minami ◽  
Miyako Imai ◽  
Ryosuke Nakano
Keyword(s):  
Granulosa Cells ◽  
Ovarian Follicles ◽  
Immunohistochemical Localization ◽  
Female Rats ◽  
Positive Staining ◽  
Immature Female ◽  
Immature Rat ◽  
Medical College ◽  
Thecal Cells ◽  
Rat Ovary

Kobayashi M, Yamoto M, Minami S, Imai M, Nakano R. Immunohistochemical localization of inhibin α- and βA-subunits in the ovary of immature female rats. Eur J Endocrinol 1995;132:97–102. ISSN 0804–4643. Immunohistochemical localization of inhibin α- and βA-subunits was examined in the ovaries of immature female rats. The granulosa cells in various sized ovarian follicles obtained from rats that were 10–24 days old exhibited positive staining for inhibin α- and βA-subunits. The relative intensities of immunostaining for α- and βA-subunits increased during follicular growth and maturation. Ova and internal thecal cells did not show any immunostaining for inhibin α- and/or βA-subunits. These results suggest that granulosa cells of immature rat ovaries may produce inhibin from the 10th day after birth, and that an increase in the number of mature ovarian follicles results in an increase in inhibin production in the immature rat ovary during prepubertal development. Mitsuko Kobayashi, Department of Obstetrics and Gynaecology, Wakayama Medical College, 1 shichibancho, Wakayama 640, Japan

scholarly journals Effect of Melatonin and Calmodulin in an Idiopathic Scoliosis Model

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Jun-Zhe Wu ◽  
Wen-Hua Wu ◽  
Li-Jiang He ◽  
Qing-Feng Ke ◽  
Long Huang ◽  
...  
Keyword(s):  
Intraperitoneal Injection ◽  
Early Period ◽  
Natural Process ◽  
Female Rats ◽  
Continuous Illumination ◽  
Significant Difference ◽  
Group A ◽  
Group B ◽  
The Sacrifice ◽  
Group D

Background. To explore influence of continuous illumination, luzindole, and Tamoxifen on incidence of scoliosis model of rats.Methods. Thirty-two one-month-old female rats were rendered into bipedal rats. The bipedal rats were divided into 4 groups: group A by intraperitoneal injection of luzindole and continuous illumination; group B by intraperitoneal injection of luzindole only; group C by intraperitoneal injection of luzindole and oral administration of Tamoxifen; and group D by intraperitoneal injection of equivalent saline. Radiographs were taken at 8th week and 16th week, and incidence and the Cobb angles of scoliosis were calculated. At 16th week, all rats were sacrificed. Before the sacrifice, the levels of calmodulin were measured in each group.Results. At 8th week, scoliosis occurred in groups A and B, with an incidence of 75% and 12.5%, respectively, while rats in group C or D had no scoliosis. At 16th week, scoliosis incidences in groups A and B were 57% and 62.5%, respectively. No scoliosis occurred in group C or D. Calmodulin in platelets in group B was significantly different, compared with groups A and D. There was no significant difference in calmodulin in platelets in groups B and C.Conclusion. By intraperitoneal injection of luzindole in bipedal rats, scoliosis rat models could be successfully made. Under light, incidence of scoliosis may be increased at an early period but it is reversible. Tamoxifen can suppress natural process of scoliosis.

scholarly journals Mycotoxin Binders Effect on Ovaries of Pregnant Mice Exposed to Zearalenone

2019 ◽  
Vol 37 (1) ◽  
pp. 127
Author(s):  
Ragil Angga Prastiya ◽  
Abdul Samik ◽  
Amung Logam Saputro
Keyword(s):  
Corpus Luteum ◽  
Cytotoxic Effect ◽  
Caspase 3 ◽  
Treatment Time ◽  
Negative Control ◽  
Gradual Decline ◽  
Cytotoxic Effects ◽  
Reproduction System ◽  
Significant Difference ◽  
Pregnant Mice

Mycotoxin, a secondary metabolite produced by mushroom, has proven to cause various cytotoxic effects to animals. Zearalenone is one type of mycotoxin which is produced by Fusarium graminearum mushroom and has a cytotoxic effect to the reproduction system and cattle productivity by inducing apoptosis in the animal's ovaries, uterus, and placenta. This research tested the potentials of mycotoxin binders in eliminating the effect of zearalenone which can be seen from the expression of caspase 3, the content of malondialdehyde (MDA), and the quantity of corpus luteum in the ovaries of pregnant mice (Mus musculus). Twenty mice were grouped into five different treatments, namely K+ (not exposed to zearalenone and mycotoxin binders), K- (0.1 mg/mouse/day of zearalenone dosage), P1 (0.1 mg/mouse/day of zearalenone dosage and 0.5 mg/mouse/day of mycotoxin binder dosage), P2 (0.1 mg/mouse/day of zearalenone dosage and 1 mg/mouse/day of mycotoxin binders), and P3 (0.1 mg/mouse/day of zearalenone and 2 mg/mouse/day of mycotoxin binders), with 10-days treatment time. The results showed that the potentials of mycotoxin binders could be found on the gradual decline in the expression of caspase 3 in P1, P2 and P3 compared to that in K- (negative control). The results also showed a significant difference in the content of malondialdehyde (MDA) in K- compared to that in K+, P1, P2, and P3. Meanwhile, the quantity of corpus luteum in K- was also starkly different to that in K+, P1, P2, and P3. It can then be concluded that mycotoxin binders are very effective in eliminating the exposure of zearalenone. 

scholarly journals Melatonin may prevent or reverse polycystic ovary syndrome in rats

2019 ◽  
Vol 65 (7) ◽  
pp. 1008-1014
Author(s):  
Leonardo Augusto Lombardi ◽  
Leandro Sabará de Mattos ◽  
Ricardo Santos Simões ◽  
Rinaldo Florencio-Silva ◽  
Gisela Rodrigues da Silva Sasso ◽  
...  
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Corpus Luteum ◽  
Rat Model ◽  
Polycystic Ovary ◽  
Female Rats ◽  
Ovarian Cysts ◽  
Ovary Syndrome ◽  
Ki 67 ◽  
Melatonin Administration ◽  
Before And After

SUMMARY OBJECTIVE To evaluate the ovarian effects of melatonin (Mel) in a rat model of polycystic-ovary-syndrome (PCOS) before and after permanent estrus induction. METHODS Thirty-two adult-female rats with regular estrous cycle were equally divided into four groups: 1) GCtrl – at estrous phase. 2) GPCOS - at permanent-estrous phase. 3) GMel1 – treated for 60 days with Mel (0.4 mg/Kg) during permanent estrus induction and 4) GMel2 – rats with PCOS and treated for 60 days with Mel. After that, the animals were euthanized, and the ovaries were removed and processed for paraffin embedding. Sections were stained with H.E. for histomorphometry or subjected to immunohistochemistry for Ki-67 and cleaved caspase-3 (Casp-3) detections. RESULTS The GPCOS showed lack of corpus luteum and several ovarian cysts, as well as interstitial-like cells. The presence of corpus luteum and a significant increase in primary and antral follicles were observed in Mel-treated groups, which also showed a decrease in the number of ovarian cysts and in the area occupied by interstitial-like cells. These results were more evident in GMel1. The percentage of Ki-67-positive cells was significantly higher in the Mel-treated groups, mainly in the GMel2, as compared to GPCOS. On the other hand, the percentage of Casp-3-positive cells was significantly lower in granulosa cells of GMel1, whereas it was significantly higher in the interstitial-like cells of GMel2, in comparison to GPCOS. CONCLUSION Melatonin administration prevents the permanent estrus state in the PCOS rat model. This effect is more efficient when melatonin is administered before permanent estrus induction.

Effect of blocking oestrogen synthesis with a new generation aromatase inhibitor CGS 16949A on follicular maturation induced by pregnant mare serum gonadotrophin in the immature rat

1994 ◽  
Vol 142 (3) ◽  
pp. 563-570 ◽  
Author(s):  
N Selvaraj ◽  
G Shetty ◽  
K Vijayalakshmi ◽  
A S Bhatnagar ◽  
N R Moudgal
Keyword(s):  
Aromatase Inhibitor ◽  
Granulosa Cells ◽  
Follicular Development ◽  
Treated Group ◽  
Female Rats ◽  
Percentage Increase ◽  
Follicular Maturation ◽  
Significant Difference ◽  
New Generation ◽  
Pregnant Mare Serum Gonadotrophin

Abstract While the endocrine role of oestrogen is well established, its function in follicular maturation as an autocrine or paracrine regulator is less well understood. This study was designed to delineate the requirement of oestrogen for follicular development in immature rats. Exogenous gonadotrophin (25 IU pregnant mare serum gonadotrophin (PMSG) per rat) was administered to 21- to 23-day old female rats to induce follicular growth and development. In the experimental animals, synthesis of oestrogen was blocked by implanting an Alzet pump containing the aromatase inhibitor (AI) CGS 16949A (fadrozole hydrochloride; 50 μg/rat per day). The treatment resulted in blockade of the PMSG induced increase in both serum and intrafollicular oestrogen (>95%), thus leading to an inhibition in uterine weight increment. Compared with the controls, ovarian weight increased markedly in both the PMSG (295%)- and PMSG+AI (216%)-primed animals. There was no significant difference in either the proliferative capabilities of the ovarian granulosa cells or their responsiveness to human chorionic gonadotrophin (hCG; 200 pg/ml) and ovine FSH (20 ng/ml) between the PMSG- and PMSG+AI-treated groups. Histological examination of the ovary, however, indicated a decrease in the number of healthy antral follicles in the AI-treated group compared with the PMSG-primed animals but both the groups showed a percentage increase over the controls (PMSG, 225; PMSG+AI, 158). The responsiveness of the animals to an ovulatory dose of hCG was drastically reduced (>80% inhibition of ovulation) in the oestrogen-deprived animals; this could be overriden by exogenous administration of oestrogen. In conclusion, although blocking oestrogen synthesis in the PMSG-primed rat does not seem to alter the functional properties of the isolated granulosa cells in vitro there appears to be an effect on the number of follicles which complete maturation and are able to ovulate in vivo. Journal of Endocrinology (1994) 142, 563–570

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