Nitric oxide synthase expression and nitric oxide/cyclic GMP pathway in swine granulosa cells

The present investigation was undertaken to verify if the two nitric oxide synthase isoforms, eNOS and iNOS, are present in swine granulosa cells and whether the enzyme soluble guanylate cyclase is functionally active in the same cells and can account for NO effects. Using western blotting, the presence of endothelial NO synthase was demonstrated in freshly collected cells; on the contrary, iNOS expression was not observed in the same cells either before or after culture with the inflammatory cytokine hTNF-alpha. The treatment with a strong NO donor (S-Nitroso-L-acetyl penicillamine, SNAP) determined an increase of cGMP levels in culture media, which was attenuated by the combined treatment with an inhibitor of NO-sensitive soluble guanylate cyclase, 1H-[1,2,3]oxadiaziolo [4,3a]quinoxaline -1-one (ODQ). The cGMP analog, 8 bromo-cGMP, mimicked the strong inhibitory effect exerted by SNAP on estradiol 17 beta and progesterone production, while ODQ did not modify steroids concentrations in culture media. These observations demonstrate the presence of a follicular NO-generating system, which in swine granulosa cells seems to include only the endothelial NOS isoform. Furthermore, the nitric oxide/cyclic GMP system seems to be functionally active in these cells, since cGMP appears to mediate NO action, even if it cannot account completely for NO inhibitory effect on steroidogenesis.

IGF-I, IGFBP-2 and -3 but not GH concentrations are different in normal and poor growing piglets

In this study we investigated the somatotropic axis in piglets with evident growth delay. Female Suffolk crossbred piglets (30 days old; N = 12) were divided into normal weight (10 +/- 0.9 kg) and poor growing subjects (7 +/- 0.5 kg) and bled for growth hormone (GH), Insulin-like growth factor-I (IGF-I), Insulin-like growth factor binding protein 2 and 3 (IGFBP-2 and -3) determination. Basal and induced-GH levels were not different in the groups. Plasma IGF-I concentrations were significantly different (p < 0.001): 101.8 +/- 9.8 ng x mL(-1) (normal weight group) and 39.5 +/- 4.0 ng x mL(-1) (poor growing group). IGFBP-2 and -3 concentrations were significantly (p < 0.001) lower in poor growing than in normal piglets. Piglet weight was positively correlated (r = 0.98, p < 0.001) with IGF-I and IGFBP-2 or -3 concentrations. Our data indicate that growth rate was not correlated to basal or secretagogue-induced GH secretion.

Role of androgens in proliferation and differentiation of mouse mammary epithelial cell line HC11

Androgens have been found in mammary epithelium and in milk throughout the cycle of the mammary gland in vivo. The aim of this study was to investigate the possible role of these substances in mammary epithelial growth and differentiation in the mouse HC11 cell line. Cells were stimulated with testosterone, dihydrotestosterone, androstenedione and 5alpha-androstane-3alpha,17beta-diol at concentrations ranging between 0.3 nM and 30 nM. Cyproterone acetate or flutamide, androgen receptor antagonists, (3 microM) were used to block specific androgen effects. Proliferative effects were measured by an MTT (tetrazolium blue) conversion test and [(3)H]thymidine uptake. HC11 cells were transfected with pbetacCAT, a chimeric rat beta-casein gene promoter-chloramphenicol acetyl transferase (CAT) gene construct and CAT ELISA was used to determine gene expression. RT-PCR was performed to detect androgen receptor expression. After 24, 48 and 72 h androgens significantly (P<0.05) increased proliferation. Androgen antagonists significantly (P<0.05) reduced the proliferative effects. Furthermore androgens potentiated the lactogenic effect of prolactin, insulin and dexamethasone (P<0.05). Finally, the androgen receptor gene was expressed in both proliferating and differentiated HC11 cells. These observations lead us to hypothesize an activity of this class of steroids in mammary physiology. In particular, androgens stimulate cell proliferation and beta-casein gene expression; this influence appears to be mediated by androgen receptors.

Selenium stimulates estradiol production in bovine granulosa cells: possible involvement of nitric oxide

Reduction in fertility is well known to be possibly related to selenium deficiencies, even if target organ for selenium action is, at present, unclear. The present study was aimed to examine whether selenium directly influences granulosa cells. Bovine granulosa cells from different size follicles were used to investigate the effect of selenium (5 ng/ml), with or without bovine follicle-stimulating hormone (bFSH) (100 ng/ml), on proliferation and steroidogenesis. In addition, we sought to determine if selenium modulates the production of nitric oxide, which is known to play an important role in ovarian activity. Our data demonstrate that selenium significantly (P < 0.001) stimulates the proliferation of the cells from small follicles; moreover, it further potentiates the stimulatory effect of the gonadotropin in the same cells. Furthermore, selenium significantly (P < 0.01) augments E2 output by cells from both kinds of follicles. bFSH increases E2 production (P < 0.01) by cells from large follicles, whereas it exerts a stimulatory (P < 0.01) effect only in the presence of selenium in the cells from the small ones. The production of nitric oxide is significantly increased (P < 0.001) by bFSH, but only in cells from small follicles. Selenium inhibits (P < 0.001) nitric oxide production in cells from both kinds of follicles and significantly decreases (P < 0.001) bFSH-induced nitric oxide production in cells from the small ones. We conclude that selenium acts on granulosa cells by modulating their proliferation and E2 synthesis; moreover, its effect could be mediated, at least in part, through an inhibition of nitric oxide.

Is nitric oxide an autocrine modulator of bovine granulosa cell function?

Nitric oxide (NO) is an important intra- and intercellular messenger controlling many biological processes. It is synthesized by NO synthases, which have been found also in granulosa cells. The present study examined whether NO is present in bovine follicular fluid and is produced by granulosa cells in culture. Secondly, it aimed to determine if NO affects the main parameters of granulosa cell function. The NO donor S-nitroso-L-acetyl-penicillamine (10(-3), 10(-4), 10(-5) M) was used to evaluate whether NO might influence steroidogenesis, proliferation and apoptosis in bovine granulosa cells collected from follicles divided according to their size in small (<5 mm) and large (>8 mm). The data demonstrate the presence of NO in follicular fluid and its production by granulosa cells in culture: the most active cells in producing NO are those from the small follicles, as confirmed by the NO levels in follicular fluid. This study also shows that NO donor significantly (P<0.001) inhibits progesterone (P4) and oestradiol 17beta (E2) production by the granulosa cells from both kinds of follicle; moreover, the highest concentration of NO donor significantly (P<0.001) inhibits DNA fragmentation in all the cells whereas the lowest concentration stimulates (P<0.001) cellular apoptosis only in granulosa cells from large follicles. NO donor does not seem to modify cell proliferation. Taken together these data lead point to NO as a local modulator of granulosa cell function.

Interleukin-1 beta fragment (163-171) modulates bovine granulosa cell proliferation in vitro: dependence on size of follicle

The biological effects of IL-1 on ovarian function have been considered as an inflammatory-like reaction. The peptide fragment of IL-1 (163-171 aa), which belongs to the active site of the whole protein, has been shown to exert an immunostimulatory activity without inducing inflammatory effects. The aim of this study was to investigate whether IL 163-171, alone or associated with bFSH, modulates granulosa cell proliferation; in addition, we wanted to assess if IL 163-171 interferes with FSH binding to receptors. Bovine follicles were divided according to their size. Cell proliferation, assessed by [3H]-thymidine uptake and [125I]-FSH binding, were studied in cells treated with IL 163-171(0, 0.5, 5 and 20 ng/ml) with or without bFSH (100 ng/ml) for 24, 48 or 72 h. Basal incorporation of [3H]-thymidine into granulosa cells from small follicles was always 3-fold higher (P < 0.01) than that by cells from large follicles. IL 163-171 did not show any effect in granulosa cells from large follicles but stimulated (P < 0.01) [3H]-thymidine uptake into granulosa cells from small follicles; furthermore IL 163-171 interacted positively with bFSH (P < 0.01) after 48 and 72 h. IL 163-171 significantly reduced (P < 0.05) FSH binding in cells from small follicles after 24 h, but not after 48 and 72 h. This data demonstrates that: (1) Follicular size and cell proliferation are inversely related; (2) IL 163-171 modulates granulosa cell proliferation only in cells from small follicles; and (3) the interaction between IL 163-171 and FSH does not mainly occur at receptor level.

Modulation by galanin of growth hormone and gonadotropin secretion from perifused pituitary and median eminence of prepubertal male calves

Galanin is widely distributed in the peripheral and central nervous system and has been indicated as a putative hypothalamic-hypophysiotropic hormone. This study was performed to investigate the effects of galanin on both growth (GH) and luteinizing hormones (LH) from pituitaries of young male calves. Pituitary slices (P, 500 microm in thickness) were perfused alone or coincubated with median eminence terminals (ME) in DMEM-F12 plus BSA 0.1% and antibiotics. The perifusion chambers were kept in equilibrium for 150 min, and medium samples were collected every 10 min for 240 min and stored at -20 degrees C until the measurement of LH and GH levels. Basal GH release increased up to 60% after galanin infusion (p < 0.01 vs. baseline levels) for 60 min in P alone; in P + ME coincubation, galanin-stimulated GH secretion was further increased by up to 200%. Basal LH release in chambers with P was significantly increased (up to 25%; p < 0.05) for 70 min after galanin infusion; P + ME coincubation showed a galanin-mediated increase in LH release of up to 50%. GH and LH responsiveness to exogenous GH-releasing hormone and gonadotropin-releasing hormone was not significantly modulated by galanin in our experimental model. In conclusion, galanin is demonstrated to have a significant stimulatory role in the secretion of GH and LH, with a combined action at both the hypothalamic and pituitary levels. ......................

Effects of interleukin-1 beta fragment (163-171) on progesterone and estradiol-17 beta release by bovine granulosa cells from different size follicles

Recent studies indicate that interleukin-1 beta may play a role in ovarian function. To explore this possibility, we examined the effects of a fragment of interleukin-1 beta (163-171 aa) on progesterone and estradiol-17 beta production by bovine granulosa cells from small (< 5 mm) and large (> 8 mm) follicles; in addition we investigated the distribution of monocytes/macrophages, a possible source of interleukin-1 beta in the follicles, to determine a possible relationship between production of the cytokine and its activity. Bovine follicles were divided according to the size, granulosa cells were obtained by aspiration and plated at a density of 10(5) cells/well; then different concentrations of interleukin-1 beta fragment (0, 0.5, 5, 20 ng/ml) with or without bFSH were added for 24 h. Progesterone (P4) and estradiol-17 beta (E2) concentrations in media were evaluated by validated RIAs. Interleukin-1 beta (0.5 and 5 ng/ml) stimulated (P < 0.05) P4 output in both small and large follicles, while FSH-induced P4 output was reduced (P < 0.05) in large but not in small follicles by all the concentrations of peptide. FSH-induced E2 output was reduced (P < 0.05) in large, but not in small follicles. Immunohisto- and cytochemistry revealed a higher number of monocytes/macrophages in large follicles. It appears from our data that: (1) interleukin-1 beta fragment may modulate steroidogenesis in bovine granulosa cells depending on the stage of development of the follicle, and (2) the presence of monocytes/macrophages is related to this modulation.

Follicle-stimulating hormone-testosterone interaction in modulating steroidogenesis in bovine granulosa cells. I. Effect on progesterone production

The aim of this study was to investigate the effects of testosterone on basal and follicle-stimulating hormone (FSH)-induced progesterone production by cultured bovine granulosa cells. Granulosa cells were isolated from small (< 5 mm) and large (> 8 mm) follicles and cultured for 48 h in 1 ml of Medium-199 with different concentrations of FSH (0.1, 1, 10 and 35 mg/l). In addition, the combined effects of different amounts of testosterone (1 nmol-10 mumol) and 1 mg/l FSH for 48 h on progesterone production by granulosa cells of both groups of follicles were studied; progesterone production during the subsequent 24-h incubation period was evaluated in the absence of hormones. In a third experiment, granulosa cells were treated with 500 micrograms of dibutyryl-cAMP and 10 mumol of testosterone for 48 h. At the end of each incubation period, the progesterone content in the culture media was determined by a validated radioimmunoassay. Basal progesterone release during the 48-h incubation period was higher in granulosa cells from small as compared to cells from large follicles; in both groups of cells, progesterone production was stimulated maximally by 1 mg/l FSH. The treatment with 10 mumol of testosterone induced a decrease of progesterone production in both groups of cells, while lower amounts exerted an inhibitory effect only in cells from large follicles. Furthermore, 10 mumol of testosterone inhibited FSH-induced progesterone release, while lower dosages were ineffective. Dibutyryl-cAMP stimulated significantly the progesterone output by granulosa cells of both groups and testosterone was effective in suppressing this increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of gonadal steroids on tonic luteinizing hormone (LH) release and luteinizing hormone-releasing hormone-induced LH release from bovine pituitary cells cultured in vitro

The objective of this study was to investigate the direct effect of estradiol-17 beta (E2) and progesterone (P4) on LH release by pituitary cells of midluteal phase cows in vitro. Pituitaries were collected at the slaughterhouse; cells were dissociated with collagenase and hyaluronidase and maintained in a static culture system in Medium 199 (M199). Various concentrations of E2 (0.1-100 nM) and P4 (0.1 and 10 nM) were used to stimulate the cells for 2, 4, 6, 15, 24, 48, or 72 h. In addition, the synergistic action of E2 and P4 was investigated by exposure of the cells to a combination of the two hormones. At the end of each incubation, the cells were challenged with LHRH (1 nM) for 2 h. The medium was collected for LH analysis at the end of each incubation period and after the LHRH challenge; furthermore, intracellular LH content was quantified at the end of each experiment. The results indicate a positive action of E2 on basal release of LH beginning after 15 h of exposure (p < 0.01). LHRH-induced LH release was modulated by E2 in a time-dependent manner with an effect at first inhibitory, then stimulatory, and finally inhibitory again (p < 0.04). P4 alone did not affect LH release, but it negatively influenced LHRH-induced LH release. P4 also exerted a positive action on intracellular LH after 6 h of incubation. A substantial inhibitory effect (p < 0.001) on both tonic LH release and LHRH-induced LH release was observed in cells exposed for 16 h to P4 after a priming with E2 for 4 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of melatonin on the in vitro secretion of progesterone and estradiol 17 beta by ovine granulosa cells

This study was undertaken to determine the effect of melatonin on steroid hormone production by ovine granulosa and luteal cells in vitro. Granulosa and luteal cells from ovine ovaries were cultured for nine days either in D-MEM only or in the presence of melatonin (0.86, 8.6, 86 nmol/l), ovine luteinizing hormone (oLH, 2 micrograms/l) or a combination of both these hormones. Progesterone (P4) and estradiol 17 beta (E2) were determined by validated RIAs. Melatonin stimulation began at either day 1 or day 5 of culture. Melatonin (0.86 nmol/l) significantly increased (p < 0.001) progesterone secretion by granulosa cells both when administered alone and when administered in combination with oLH; the more marked response was observed in the latter case. When the stimulation began at day 5, at a more advanced degree of differentiation of the cells, higher levels of P4 were observed. Higher concentrations of melatonin did not further increase progesterone production. Melatonin alone did not have a significant effect on the production of estradiol 17 beta; neither did melatonin stimulate progesterone production in either long-term cultured luteal cells or in short-term (1-2 h) cultured luteal and granulosa cells. The results of this study document a direct effect of melatonin in stimulating granulosa cells to produce progesterone, a synergistic activity between melatonin and luteinizing hormone and a different ability of granulosa cells to secrete P4 depending on the degree of differentiation.

Seasonal variation in the reproductive hormones of male goats

The aim of this work was to study the circannual plasma profiles of LH, PRL, testosterone (T) and estrone sulfate (E1S) in different periods of the year and to characterize the possible variations in LH and PRL release patterns. We also tried to verify a possible relationship between plasma PRL fluctuations and ambient temperature, as well as the influence of an acute stress condition on levels of plasma PRL. Six adult male goats of the Ionica and Alpine breed reared in Southern Italy (40 degrees N lat.) were subjected to frequent samplings (every 15 min for 6 h) once a month for a whole year. The blood samples were assayed for plasma concentrations of E1S, LH and PRL by radioimmunoassay, and for T by enzymeimmunoassay. The ambient temperature was recorded on each day of bleeding. Sex steroids and PRL showed marked circannual variations, with the highest levels during the summer (July) and the lowest during the winter-early spring (March). The concentrations of plasma LH did not indicate significant seasonal variations. A positive relationship was observed between plasma levels of PRL and E1S and ambient temperature. The patterns of LH release seemed to change depending on season, but this was not an obvious and common feature in all bucks. The hormone concentrations for plasma PRL profiles seemed to be influenced by an acute stress condition (associated with cannula insertion and handling procedures), with the variations more marked when the plasma levels of PRL were low.

Progesterone does not inhibit the increase in pituitary content of luteinizing hormone after removal of estradiol in the ewe

During late gestation in the ewe, the pituitary content of LH is reduced by about 95%, presumably due to the presence of high concentrations of ovarian steroids. The aim of this study was to determine whether the pituitary content of LH in the ewe can increase after long-term administration of ovarian steroids, when only estradiol (E) is removed or if both E and progesterone (P) must be withdrawn to allow synthesis of LH to occur. Ten ovariectomized ewes were treated with implants containing E and P. After 3 weeks of treatment, the E implants were removed from 5 ewes (-E+P) and both steroid implants were removed from the remaining 5 ewes (-E-P). Five ovariectomized ewes received P implants at the beginning of the experiment and these implants were left in place for the duration of the study; 5 ovariectomized ewes served as controls (C). All animals were injected with 100 micrograms GnRH iv 3, 6 and 9 weeks after the initiation of treatment. The area under the LH-response curve was used as an indication of the pituitary content of LH. All steroid treatments markedly reduced basal levels of LH. LH levels increased only in -E-P ewes, beginning 6 weeks after initiation of the study. After 3 weeks, -E+P and -E-P ewes released less LH (P less than 0.05) in response to GnRH than did C ewes, whereas P animals did not differ from controls. LH release in response to GnRH in -E+P and -E-P groups had increased by 6 and 9 weeks and was not different from that of C ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Reproductive performance of female goats given progestagen associated with PMSG and/or HMG in deep anestrus

During deep anestrus and after a 21-day fluorogestone acetate (FGA) treatment, 200 pluriparous lactating Alpine goats were given randomly one of four treatments: (A) 500 IU of pregnant mare serum gonadotropin (PMSG) 48 h before sponge removal; (B) 500 IU of PMSG 48 h before sponge removal and an ampoule of human menopausal gonadotropin (HMG) at sponge removal; (C) two ampoules of HMG at sponge removal; (D) four ampoules of HMG at sponge removal. All the goats were mated naturally during estrus. The percentage of goats kidding (fertility rate) was 6, 34, 40 and 36% for groups A, B, C, and D, respectively; the number of kids/pregnant female (prolificacy) averaged between 1.33 and 1.72. The accuracy of pregnancy diagnosis on the basis of plasma progesterone concentration 20 to 22 days after mating was not particularly satisfactory, mainly because many pregnant goats, and especially group A goats, showed abnormally prolonged luteal activity. The determination of total estrone 60 days after mating gave almost 100% overall accuracy.

Effects of oestradiol and progesterone on pulsatile secretion of luteinizing hormone in ovariectomized ewes

The effect of treatment with oestradiol, progesterone, a combination of the two steroids or no steroids on pulsatile release of luteinizing hormone (LH) was examined in ovariectomized ewes. Beginning 3 days after ovariectomy, 5 ewes were assigned to each of the following treatment groups: 0.7 mg oestradiol, 16 mg progesterone, 0.7 mg oestradiol plus 16 mg progesterone or no steroid. All treatments were administered twice daily for 3 weeks in a 0.5 ml injection of ethanol given sc. After 2 weeks of treatment and 1, 4, 8, 16 and 32 days after the treatment period ended, blood samples were obtained from all ewes at 10-min intervals for a 6-h period. At the end of the 6-h period, 100 micrograms gonadotrophin-releasing hormone (GnRH) was injected iv and blood samples were collected at 15 min intervals for an additional 5 h to estimate the relative pituitary content of LH. Ovariectomized ewes receiving no steroid presented regular pulses of LH at frequency of four to five pulses during a 6-h sampling period. Treatment with progesterone alone decreased the frequency of pulsatile release of LH to approximately 1 pulse/6 h, but did not affect the amplitudes of the pulses of LH. Recovery of pulsatile release of LH to a frequency of four or five pulses of LH in a 6-h period was complete between 16 ewes. Oestradiol, administered alone or with progesterone, resulted in a decrease in both the frequency and the amplitude of pulses of LH compared to control ewes and a decrease in GnRH-induced release of LH.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma cortisol variations induced in the stallion by mating

Plasma cortisol variations have been determined by radioimmunoassay in 5 stallions during mating and in 2 teasers during oestrous female exposure. In all the animals, cortisol plasma levels consistently increase (71.1 ng/ml vs 44.0 and 63.0 ng/ml vs 35.1, in the stallions and in the teasers, respectively) 7-30 min after female exposure; 120 min after exposure, cortisol concentrations are again low.

Progesterone, estrogen, LH, FSH and PRL concentrations in plasma during the estrous cycle in goat

Progesterone, estrogen, LH, FSH and PRL variations in plasma were measured in 7 goats by RIA. Mean progesterone level was 0.0-0.8 ng/ml in estrus and 1-4 ng/ml in diestrus. Estrogen levels ranged from 10 to 20 pg/ml in diestrus; around estrus, a peak of 26.9 +/- 3.18 pg/ml was observed. LH values were 0.5-3.0 ng/ml with a preovulatory peak (40.7 +/- 10.12 ng/ml) 8 to 24 h after the onset of estrus. Except for a peak (14.0 +/- 3.09 ng/ml) coincident with LH surge, plasma FSH level ranged between 2 and 4 ng/ml. PRL level averaged 2-5 ng/ml in diestrus but high concentrations of this hormone were seen around estrus.

Concentrations of progesterone, 17 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone in the plasma of mares during pregnancy and at parturition

Plasma concentrations of progesterone and 17 alpha-hydroxyprogesterone were high in the 2nd and 3rd months of gestation, but 20 alpha-dihydroprogesterone increased from a level of 2 ng/ml, during the first 3 months, to 10-15 ng/ml during months 5-10, to reach 80-120 ng/ml during the last 30 days before foaling.