Suppression in the secretion of follicle-stimulating hormone and luteinizing hormone, and ovarian follicle development in heifers continuously infused with a gonadotropin-releasing hormone agonist

A novel experimental model was developed in cattle to investigate the requirement for FSH and LH during ovarian follicle growth and development. On Day 5 of the estrous cycle, 7 heifers were each implanted with an osmotic minipump containing a GnRH agonist (GnRHa), Buserelin (release rate, 2.5 micrograms/h). Another 7 heifers served as controls. Each minipump was replaced 28 days later with a second pump, which was left in place for a further 20 days. Blood samples were collected daily throughout the experimental period, and frequent samples were also collected on both days of minipump insertion and at 10 days after insertion of the second pump. The ovaries of all heifers were scanned daily by real-time ultrasonography to monitor follicular dynamics. All controls displayed 2 or 3 waves of FSH and follicular development per estrous cycle during the experiment. Insertion of the first minipump produced a large LH and FSH surge and induced ovulation in all 7 animals. Within 8 days of the start of treatment, serum LH concentrations fell to basal levels; they then remained constant at this level throughout the infusion period, only beginning to recover 4-5 days after the termination of infusion. After the initial increase, FSH returned to basal levels before showing a normal wave that was coincident with the emergence, growth, and regression of a dominant follicle. However, despite the peak levels of FSH, dominant follicles from the next wave failed to grow beyond 7-9 mm; they remained at this size for 3 wk until 3-4 days after insertion of the second minipump, when FSH fell precipitously to reach low levels that were maintained throughout the remainder of the infusion. After this fall in FSH concentrations, these follicles regressed rapidly, and no antral follicles > 4 mm were detected until after the termination of treatment. Thereafter, FSH concentrations increased significantly; the increase was accompanied by the emergence of a follicular wave and development of a dominant follicle, with estrus observed 8-11 days later. In conclusion, this study has demonstrated clearly that in cattle the early stages of follicle development (< or = 4 mm) are not dependent on acute support by gonadotropins. However, FSH is required for further growth of follicles up to 9 mm, while LH pulses are indispensable for follicle development beyond 9 mm in diameter. The model developed in this study should be valuable for studying the control of ovarian follicle development and atresia in vivo.

Oligodeoxynucleotides inhibit retinal neovascularization in a murine model of proliferative retinopathy

Diseases characterized by retinal neovascularization are among the principal causes of visual loss worldwide. The hypoxia-stimulated expression of vascular endothelial growth factor (VEGF) has been implicated in the proliferation of new blood vessels. We have investigated the use of antisense phosphorothioate oligodeoxynucleotides against murine VEGF to inhibit retinal neovascularization and VEGF synthesis in a murine model of proliferative retinopathy. Intravitreal injections of two different antisense phosphorothioate oligodeoxynucleotides prior to the onset of proliferative retinopathy reduced new blood vessel growth a mean of 25 and 31% compared with controls. This inhibition was dependent on the concentration of antisense phosphorothioate oligodeoxynucleotides and resulted in a 40-66% reduction in the level of VEGF protein, as determined by Western blot analysis. Control (sense, nonspecific) phosphorothioate oligodeoxynucleotides did not cause a significant reduction in retinal neovascularization or VEGF protein levels. These data further establish a fundamental role for VEGF expression in ischemia-induced proliferative retinopathies and a potential therapeutic use for antisense phosphorothioate oligodeoxynucleotides.

Exercise responses to running and in-line skating at self-selected paces

Exercise responses to running and in-line skating at self-selected paces. Med. Sci. Sports Exerc., Vol. 28, No. 2, pp. 247-250, 1996. The purpose of this investigation was to compare physiological responses to in-line skating and running at preferred levels of exertion. Ten males and ten females performed 15 min of in-line skating or running on two separate days. Subjects were instructed to exercise at an intensity that represented an effective cardiovascular workout. Heart rate (HR) and oxygen consumption (VO2) were monitored continuously using a portable, telemetric, open-circuit spirometry system. Subjects maintained steady rate VO2 over minutes 11-15 of in-line skating and running at speeds (mean +/- SD) of 21.7 +/- 2.4 and 12.2 +/- 2.3 km.h-1, respectively. A significantly higher (P = 0.03) VO2 (mean +/- SEM, 44.0 +/- 1.7 ml.kg-1.min-1) was observed during running compared with in-line skating (42.0 +/- 2.0 ml.kg-1.min-1), but there were no differences in ventilation, HR, or rating of perceived exertion. Consistent with the results of previous investigations, we conclude that in-line skating is an appropriate form of exercise for improving cardiorespiratory fitness. Future studies should compare the cardiovascular training effects of in-line skating and running in individuals of varying levels of fitness and skating ability.

Pretreatment with recombinant bovine somatotropin enhances the superovulatory response to FSH in heifers

One of the primary limiting factors to superovulation and embryo transfer in cattle has been the large variability in response, both between and within animals. It appears that the primary source of this problem is the variability in the population of gonadotropin-responsive follicles present in ovaries at the time of stimulation. We have shown that treatment of heifers with recombinant bovine somatotropin (rbGH) increases the number of small antral follicles (2 to 5 mm) and, therefore, enhances the subsequent superovulatory response to eCG. To investigate further the potential of using this approach to improve superovulatory regimens in cattle, the effect of rbGH pretreatment on the response to pituitary FSH was studied. The estrous cycles of 16 heifers were synchronized using PGF2alpha. On Day 7 of the synchronized cycle, half of the animals were injected with 320 mg sustained-release formulated rbGH, while the other half received 10 ml saline. Five days later, all heifers were given a decreasing-dose regimen of twice daily injections of oFSH for 4 d, incorporating an injection of PGF2alpha with the fifth FSH treatment, to induce superovulation. All animals were artificially inseminated twice with semen from the same bull during estrus. Ova/embryos were recovered nonsurgically on Days 6 to 8 of the following estrous cycle, and the ovulation rate assessed on Day 9 by laparoscopy. Using the same animals as described above, the experiment was repeated twice, 3 and 6 mo later, with no laparoscopy in the third experiment. The animals were randomized both between experiments and for the day of ova/embryo collection. Pretreatment of heifers with rbGH significantly (P < 0.01) increased the number of ovulations, total number of ova/embryos recovered and the number of transferable embryos. The percentage of transferable embryos was significantly (P < 0.05) increased by rbGH pretreatment. In addition, the incidence (2/16) of follicular cysts with a poor ovulatory response (< 6 ovulations) for the rbGH-pretreated heifers was significantly lower (P < 0.05) when compared with the incidence (7/16) in the control animals. It is concluded that pretreatment with rbGH may provide a useful approach for improving superovulatory response in cattle.

Breast and pelvic examinations: easing women's discomfort

OBJECTIVES

To determine whether women prefer male or female physicians for gynecologic examinations, whether they want a third person present during examinations, and what behaviour physicians and third persons should exhibit. We also sought to determine whether women had experienced any unprofessional behaviour from doctors.

DESIGN

Cross-sectional, 17-item questionnaire.

SETTING

Two Saskatchewan family practices: one rural (Melfort), one urban (Saskatoon).

PARTICIPANTS

All women 18 years old and older who visited their family physicians' offices between February and April 1993.

MAIN OUTCOME MEASURES

Patient preferences regarding physician behaviour and any perceived unprofessional behaviour.

RESULTS

Of 350 questionnaires, 336 were completed correctly. Responses indicated that 51% did not mind whether the physician was male or female, but 43% preferred female doctors. When being examined by a male physician, 62% wanted a third person present; only 30% wanted that if the physician was female. Of all women, 42% wanted the opportunity to choose whether a third person was present every time and another 19% only for the first examination by a new doctor. Supportive behaviours were indicated. "Unprofessional" conduct had been experienced by 8% of respondents.

CONCLUSIONS

Many women do not mind whether they are examined by male or female doctors. Many prefer having a third person present when the examining physician is a man. Some want the opportunity to choose whether a chaperone is present.

Induction and maintenance of oestradiol and immunoreactive inhibin production with FSH by ovine granulosa cells cultured in serum-free media

A serum-free ovine granulosa cell culture system is described that allows the induction of FSH-responsive oestradiol production by undifferentiated cells from small (< 3.5 mm) follicles (P < 0.001) and the maintenance of oestradiol production by differentiated cells from large (> or = 3.5 mm) follicles. Physiological doses of FSH stimulated (P < 0.01) proliferation of cultured granulosa cells from both small and large follicles. The synthesis of immunoreactive inhibin and progesterone by granulosa cells from small and large follicles increased (P < 0.01) with time of culture, and was not dependent on FSH. Inhibin secretion expressed on a per cell basis was not FSH responsive. Insulin and insulin-like growth factor I (IGF-I), in the presence of FSH, stimulated (P < 0.001) cell proliferation and oestradiol and inhibin production by granulosa cells from small and large follicles. There was a significant (P < 0.001) interaction between insulin and IGF-I in the stimulation of granulosa cell proliferation and differentiation. Both epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) in the presence of FSH stimulated cellular proliferation (P < 0.001) in a dose-responsive manner and concomitantly inhibited (P < 0.001) oestradiol and inhibin secretion. The development of this granulosa cell culture system will make it possible to study, in vitro, the cascade of events that controls granulosa cell differentiation and ultimately follicle selection in sheep.

Effects of chronic treatment with a gonadotrophin-releasing hormone agonist on peripheral concentrations of FSH and LH, and ovarian function in heifers

The effect of chronic treatment with a gonadotrophin-releasing hormone agonist (GnRHa) on ovarian function in cattle was investigated by injecting heifers i.m. twice a day with saline, 5 micrograms GnRHa (Buserelin) or 10 micrograms GnRHa (n = 7) for 21 days. Blood samples were taken twice a day during the treatment period, and then three times a day for 7 days and once daily for a further 4 days. Frequent samples were also collected on day 1, day 10 and day 21 of treatment. The ovaries of all heifers were examined daily using real-time ultrasonography throughout the experimental period. No significant differences in the response were observed between two doses of GnRHa. The first GnRHa injection produced a large LH and FSH surge and this acute response was still present by day 21 of treatment, but both the magnitude and duration of response were significantly attenuated (P < 0.01). After an initial increase, LH returned to the basal concentration, which was maintained until the termination of treatment, when concentrations increased significantly, with a preovulatory surge occurring approximately 6 days later. Peripheral FSH concentrations during the oestrous cycle in control animals displayed a pattern of three waves, each of which closely preceded a wave of follicular development. Concentrations of FSH in GnRHa-treated heifers showed a normal pattern for the first wave after the start of treatment. During the next wave, concentrations increased and remained at the peak values until about 4 days after the end of treatment. An additional ovulation was induced in 11 of 14 GnRHa-treated heifers within 2-3 days of the start of treatment, and a significant (P < 0.05) increase in serum progesterone concentrations was detected 2 days later. All GnRHa-treated heifers then showed a normal follicular wave, with the development and regression of a dominant follicle. The dominant follicles from the next wave grew to only 7-9 mm in diameter and remained at this size until the end of treatment, when they resumed growth, ovulated approximately 7 days later and formed corpora lutea. We conclude that chronic treatment of heifers with GnRHa for 3 weeks suppresses pulsatile secretion of LH and blocks the development of dominant follicles beyond 9 mm in diameter, preventing the preovulatory LH surge and ovulation. However, GnRHa did not suppress the secretion of FSH within the 3 week treatment period. The maintenance of the dominant follicles for an extended period should provide an ideal model to study the control of follicular atresia in cattle in vivo.

Effects of indirect selection for pituitary responsiveness to gonadotropin-releasing hormone on the storage and release of luteinizing hormone and follicle-stimulating hormone in prepubertal male lambs

Divergent selection based on the LH response to a 5-micrograms dose of GnRH in 10-wk-old Finn Dorset ram lambs has created two lines of sheep that differ significantly in their response to both physiological and pharmacological dosages of GnRH. The aims of this study were to investigate whether there are between-line differences in endogenous LH and FSH secretion in ram lambs, as in the adult ewes, and to determine whether these differences are related to differences in storage of gonadotropins within the pituitary glands of the two lines. To address the first aim, endogenous LH and FSH secretion was monitored in 20 ram lambs from each line for a 6-h period at 2, 6, and 10 wk of age. To investigate potential between-line differences in gonadotropin storage, the LH responses to two acute challenges with either 0.5, 5.0, or 50.0 micrograms of GnRH were examined in 10-wk-old ram lambs from each line. The results demonstrated that the between-line difference in the LH response to a 5-micrograms GnRH challenge in ram lambs is accompanied by significant between-line differences in the regulation of endogenous gonadotropin secretion. Specifically, lambs from the High line secreted LH pulses of significantly greater amplitude than did lambs from the low line at 2 and 10 wk of age.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of the Booroola (FecB) gene on peripheral FSH concentrations and ovulation rates during oestrus, seasonal anoestrus and on FSH concentrations following ovariectomy in Scottish Blackface ewes

The aim of this study was to investigate the role of FSH in the control of ovulation rate by the Booroola gene. Three Booroola genotypes (FecBFecB, FecBFec+ and Fec+Fec+) of the F2 population, from a cross between Booroola Merino and Scottish Blackface, and two Booroola genotypes (FecBFec+ and Fec+Fec+; 25% Booroola Merino and 75% Scottish Blackface), from the backcross of FecBFec+ sires to Scottish Blackface ewes, were compared. During seasonal anoestrus significant differences (P < 0.05) in hCG-stimulated ovulation rates were obtained between FecBFecB and Fec+Fec+ ewes from the F2 population, and FecBFec+ ewes were intermediate. No significant difference in hCG-stimulated ovulation rate was observed in the backcross population between FecBFec+ ewes and Fec+Fec+ ewes. There were no significant differences between genotypes in mean serum FSH concentrations during seasonal anoestrus in either backcross of F2 population. During the breeding season, two separate experiments confirmed the expected ovulation rate differences between genotypes (FecBFecB > FecBFec+ > Fec+Fec+). In both experiments, mean peripheral FSH concentrations in the F2 population were similar in FecBFec+ and Fec+Fec+ ewes, but were significantly higher (P < 0.05) in FecBFecB ewes. In the backcross population, mean peripheral FSH concentrations during the oestrous cycle were not significantly different between FecBFec+ and Fec+Fec+ ewes, despite significant differences in ovulation rate. Ovariectomy during the breeding season resulted in significantly higher (P < 0.001) mean peripheral FSH concentrations in all three genotypes. After ovariectomy, mean FSH concentrations between FecBFec+ and Fec+Fec+ ewes, form both backcross and F2 populations, were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

Photoaffinity labelling of the ATP-binding sites of two Ca2+,Mg-ATPase isoforms in pancreatic endoplasmic reticulum

Pancreatic rough ER ATP-binding proteins, including two isoforms of SERCA-2b Ca2+,Mg-ATPase, were identified using specific photoaffinity labelling with 8-azido-ATP. 8-Azido-ATP irreversibly inhibited Ca2+,Mg-ATPase activity only after UV irradiation and the inhibition was prevented by inclusion of 5 mM ATP in the labelling reaction. Rough ER proteins of apparent molecular masses 141, 111, 100, 84, 69, 55 and 47 kDa were detected following photoaffinity-labelling with 8-azido-[alpha-32P]ATP. The two bands at 111 kDa and 100 kDa corresponded in molecular mass to the two SERCA-2b Ca2+,Mg-ATPase isoforms previously demonstrated immunologically [1]. Immunoprecipitation of rough ER proteins by a SERCA-2b-specific antibody showed that the two ATPase bands were photoaffinity-labelled. Photoaffinity labelling of the 111 and 100 kDa proteins was: (a) abolished when Ca2+,Mg-ATPase activity was inactivated by EDTA-treatment of rough ER membranes; (b) inhibited by the Ca2+,Mg-ATPase inhibitor vanadate; (c) not affected by thapsigargin. The data demonstrate that pancreatic rough ER contains two isoforms of the SERCA-2b Ca2+,Mg-ATPase whose ATP-binding properties are susceptible to inhibition by vanadate but not thapsigargin.

Alterations in endogenous gonadotropin secretion and pituitary responsiveness to gonadotropin-releasing hormone in adult ewes, following indirect selection in prepubertal male lambs

Indirect selection to improve reproductive performance in the female, through use of a physiologically related trait in prepubertal males, the LH response to a GnRH challenge, has created two lines of sheep with altered pituitary gland sensitivity to both physiological and pharmacological doses of GnRH. These lines also exhibit correlated between-line differences in female reproductive performance during the first, and at the beginning of the second, breeding season. This study was designed to determine whether the observed between-line differences in female reproductive performance were related to between-line differences in endogenous gonadotropin secretion during the luteal and follicular phases of the estrous cycle and whether the between-line difference in the LH response to a GnRH challenge was maintained in adult females. The results indicated that, despite similar mean gonadotropin and steroid concentrations during the luteal and follicular phases of the estrous cycle, significant between-line differences in LH pulse amplitude were present during the follicular phase (high line > low line). In addition, the results indicated that the between-line difference in the LH response to a GnRH challenge was maintained in adult ewes, being most apparent during the follicular phase, when the magnitude of the difference was similar to that in prepubertal female lambs. Therefore, in addition to showing maintenance of the between-line difference in the selected characteristic in postpubertal females, the results demonstrate that adult ewes from the two lines differ in additional, unselected but physiologically related traits and provide a model system with which to study steroidal regulation of gonadotropin secretion in the ewe.

Effects of recombinant bovine somatotrophin, insulin-like growth factor-I and insulin on bovine granulosa cell steroidogenesis in vitro

Our previous studies have demonstrated that physiological concentrations of metabolic hormones, including recombinant bovine somatotrophin (BST), insulin-like growth factor-I (IGF-I) and insulin, can significantly stimulate the proliferation of bovine granulosa cells cultured under serum-free conditions. In this study we investigated the effects of these factors on bovine granulosa cell steroidogenesis using the same culture system. Bovine granulosa cells were obtained from antral follicles classified into three size classes: small, < 5 mm; medium-sized, 5-10 mm and large, > 10 mm in diameter. Whilst not affecting steroidogenesis by granulosa cells from small and medium-sized follicles, BST (10-1000 ng/ml) stimulated the secretion of both oestradiol and progesterone by granulosa cells from large follicles in a dose-dependent manner. Insulin (1-1000 ng/ml) and IGF-I (10-1000 ng/ml) stimulated the secretion of oestradiol and progesterone by granulosa cells from all three size categories of follicles in a dose-dependent manner. FSH (200 ng/ml) alone increased progesterone secretion by granulosa cells from all three size classes of follicles, but had no effect on oestradiol secretion by granulosa cells. Both IGF-I (200 ng/ml) and insulin (30 ng/ml) acted in synergy with FSH (200 ng/ml) to stimulate steroidogenesis by granulosa cells from all three size categories of follicles, but no such interaction was observed between BST (50 ng/ml) and FSH (200 ng/ml). In conclusion, BST, IGF-I and insulin significantly influence the steroidogenic activity of bovine granulosa cells cultured under serum-free conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Follicular development from ovarian xenografts in SCID mice

Cortical slices of either cat or sheep ovaries were grafted under the renal capsules of ovariectomized SCID mice. The grafts became vascularized and were still surviving with large follicles present at autopsy up to nine months later. As developing follicles undergo atresia during the period of ischaemia after ovarian grafting, those found in long-term grafts at autopsy had presumably started to grow from the primordial stage after transplantation. Some follicles had reached a diameter of 3 mm with a normal antrum and appeared to be cytologically normal, but the latent period for the emergence of antral follicles was shorter in cat compared with sheep grafts. Oestradiol production from grafts, as indicated by vaginal cornification and plasma measurements collected at autopsy, was not constant and circulating concentrations varied among animals, and were sometimes far in excess of the normal physiological range of the host. The vaginal smears never presented cytological patterns like those of the normal mouse oestrous cycle, and ovulation had not occurred in any of the grafts. These results demonstrate that ovarian xenografts in SCID mice can serve as experimental models for investigating follicle development in species in which follicle growth in vitro and studies of the parent animal are impracticable.

MapA, an iron-regulated, cytoplasmic membrane protein in the cyanobacterium Synechococcus sp. strain PCC7942

Growth of Synechococcus sp. strain PCC 7942 in iron-deficient media leads to the accumulation of an approximately 34-kDa protein. The gene encoding this protein, mapA (membrane-associated protein A), has been cloned and sequenced (GenBank accession number, L01621). The mapA transcript is not detectable in normally grown cultures but is stably accumulated by cells grown in iron-deficient media. However, the promoter sequence for this gene does not resemble other bacterial iron-regulated promoters described to date. The carboxyl-terminal region of the derived amino acid sequence of MapA resembles bacterial proteins involved in iron acquisition, whereas the amino-terminal end of MapA has a high degree of amino acid identity with the abundant, chloroplast envelope protein E37. An approach employing improved cellular fractionation techniques as well as electron microscopy and immunocytochemistry was essential in localizing MapA protein to the cytoplasmic membrane of Synechococcus sp. strain PCC 7942. When these cells were grown under iron-deficient conditions, a significant fraction of MapA could also be localized to the thylakoid membranes.

Restoration of fertility to oophorectomized sheep by ovarian autografts stored at -196 degrees C

Cortical slices were prepared from the right ovaries of six lambs and either grafted directly to the ovarian pedicles of origin or cooled slowly to liquid nitrogen temperatures in medium containing dimethylsulphoxide. Three weeks later, the contra-lateral ovary was removed and replaced with frozen-thawed slices from the same animal. Two of the animals mated during their second oestrous cycle 3-4 months later and the remainder had at least one ovulatory cycle. The pregnancies reached full-term development, one lamb being derived from an ovulation in a fresh graft and the other from a frozen-thawed graft. None of the sheep had peripheral plasma concentrations of follicle stimulating hormone or luteinizing hormone consistently in the castrate range, and only one graft was devoid of follicles when the animals were slaughtered 9 months after the operations. Grafts with primordial follicles always contained developing follicles, which occasionally attained pre-ovulatory sizes of 7 mm in diameter. A corpus albicans was present in five grafts. Since all developing follicles had degenerated 1 week after grafting in an additional ewe, the large follicles in long-term grafts had presumably commenced growing after the operation. There were no obvious differences between fresh and frozen-thawed grafts in either appearance or weight, and all had apparently grown since implantation. Despite substantial depletion of primordial follicle numbers, the results indicated that frozen storage and replacement of a patient's own ovarian tissue might be practicable when fertility potential is threatened by chemotherapy/radiotherapy.

Superovulation in red deer (Cervus elaphus) and Père David's deer (Elaphurus davidianus), and fertilization rates following artificial insemination with Père David's deer semen

Two comparative studies were undertaken using adult, female red and Père David's deer to examine the ovulatory response of these animals to a superovulation regimen and fertilization rates following inter- and intraspecific laparoscopic insemination. In Expt 1 six Père David's deer and 12 red deer hinds were treated during the breeding season with an intravaginal progesterone-impregnated controlled internal drug release device (CIDR) for 14 days, with 200 iu pregnant mares' serum gonadotrophin (PMSG) administered 72 h before the device was withdrawn and eight injections of ovine FSH given at 12 h intervals starting at the time of PMSG administration. Oestrous behaviour began one day after CIDR device withdrawal (Père David's deer: 24.00 +/- 2.32 h; red deer: 24.60 +/- 2.23 h). The duration of oestrus was greater in Père David's deer than in red deer (17.50 +/- 1.43 h and 8.25 +/- 3.25 h, respectively, P < 0.001). The peak LH surge of Père David's deer was 68.65 +/- 4.74 ng ml-1 occurring 29.00 +/- 2.41 h after removal of the CIDR devices. In comparison, the peak LH surge in red deer was 17.09 +/- 3.64 ng ml-1 (P < 0.001), occurring 24.00 +/- 0.00 h after CIDR device withdrawal. Pre-surge concentrations of LH were also greater (P < 0.001) in Père David's deer (1.37 +/- 0.11 ng ml-1) than in red deer hinds (0.41 +/- 0.02 ng ml-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Demonstration of two isoforms of the SERCA-2b type Ca2+,Mg(2+)-ATPase in pancreatic endoplasmic reticulum

An antibody raised against a 12 amino acid peptide corresponding to the C-terminal sequence of the SERCA-2b Ca2+,Mg(2+)-ATPase precipitated Ca2+,Mg(2+)-ATPase activity from pancreatic rough ER. Thapsigargin and vanadate inhibited the activity with the same concentration-dependence as for native ER membranes. Partial purification of Ca2+,Mg(2+)-ATPase using Reactive Dye-agarose affinity chromatography resulted in activation of the enzyme, suggesting the presence of an endogenous inhibitor which was detached by binding to the Reactive Dye. Immunoblots and analysis of immunoprecipitated protein revealed two bands of molecular masses approx. 111 kDa and 97 kDa. It is concluded that pancreatic ER Ca2+,Mg(2+)-ATPase is of the SERCA-2b type and consists of two isoforms.

Effects of recombinant bovine somatotrophin, insulin-like growth factor-I and insulin on the proliferation of bovine granulosa cells in vitro

Treatment of heifers with recombinant bovine somatotrophin (BST) significantly increases the population of small ovarian follicles and peripheral concentrations of somatotrophin, insulin-like growth factor-I (IGF-I) and insulin. To investigate the possible mechanism(s) involved in the action of BST on ovarian follicles, the effects of BST, IGF-I and insulin, given alone or in combination with either FSH or LH, on the proliferation of bovine granulosa cells in vitro were examined using a serum-free culture system. Bovine granulosa cells were obtained from antral follicles classified into three size categories according to diameter: small < 5 mm; medium-sized 5-10 mm and large > 10 mm. The proliferation of granulosa cells was assessed by the incorporation of [3H]thymidine into the cultured cells. Both FSH and LH (1-1000 ng/ml) inhibited the proliferation of bovine granulosa cells obtained from all three size classes of follicles in a dose-dependent manner. BST, at doses ranging from 1 to 1000 ng/ml, had no effect on the proliferation of granulosa cells from small and medium-sized follicles, but inhibited the division of granulosa cells from large follicles in a dose-dependent manner. Treatment with either IGF-I (10-3000 ng/ml) or insulin (0.5-1000 ng/ml) stimulated, in a dose-dependent manner, the proliferation of granulosa cells obtained from all three size categories of follicles. No synergistic interaction between BST (30 ng/ml) and either FSH (50 ng/ml) or LH (5 ng/ml) was observed in granulosa cells from all three size classes of follicles.(ABSTRACT TRUNCATED AT 250 WORDS)