Biomedical subjects

K Taya

Publications and source records attributed to K Taya.

At least 91 records · Page 5Linked to original sources

PubMed1997

Inhibin is involved in the suppression of FSH secretion in the growth phase of the dominant follicle during the early luteal phase in cows.

This study was carried out to examine the involvement of inhibin in the regulation of FSH secretion during the growth phase of the dominant follicle in the early luteal phase of cows. Six cows were given a single i.v. bolus injection of 100 ml inhibin antiserum raised against bovine 32-kDa inhibin in a castrated male goat, and five animals received the same amount of castrated male goat serum (control serum) on Day 5 of the estrous cycle (Day 0 = estrus). All animals in each group experienced a wave of follicular development after ovulation, and the dominant follicle was over 8.5 mm in diameter on Day 5. The corpus luteum was identified for each group on Day 5. Plasma concentrations of estradiol and progesterone gradually increased after ovulation and reached around 3.7 pg/ml and 3.0 ng/ml on Day 5, respectively, suggesting that the dominant follicle and corpus luteum were functional. Administration of inhibin antiserum produced a clear increase (P < 0.001) in plasma FSH within 8 hr compared with that in control animals. Plasma levels of luteizing hormone showed a moderate increase during 40 hr after the injection of antiserum (P = 0.08). A large number of antral follicles (4 mm in diameter) developed after the hypersecretion of FSH, coupled with the rise in plasma estradiol levels. These results clearly demonstrated that inhibin neutralization during the early luteal phase produces hypersecretion of FSH with a coincident stimulation of follicular development, indicating that inhibin is an important factor for the negative regulation of FSH secretion during the early luteal phase when secretion of estradiol and progesterone are normally high.

Analysis of Variance↗

PubMed1997

Effects of passive immunization against oestradiol-17beta and inhibin on the secretion of gonadotrophin in the cyclic golden hamster (Mesocricetus auratus).

To investigate the physiological importance of oestradiol-17beta and inhibin in the regulation of gonadotrophin secretion in the cyclic golden hamster, females were passively immunized against two hormones. When 200 microL antiserum against oestradiol-17beta (oestradiol-AS) was given on Day 3 (Day 1 = day of ovulation), the preovulatory gonadotrophin surge was completely blocked for 24 h and the length of the oestrous cycle was also prolonged for one day. In the group given 200 microL oestradiol-AS on Day 3, basal levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) increased slightly and superovulation (19.6+/-0.8, mean+/-s.e.m.) occurred. When 200 microL antiserum against inhibin (inhibin-AS) was given at 1100 hours on Day 3, a dramatic increase in plasma FSH and a slight increase in LH were noted, resulting in superovulation (38.2+/-2.6) on the expected Day 1. The present study indicates clearly that inhibin plays a major role in regulating the specific ovulation rate in the hamster through the control of FSH secretion. Present results also indicate that oestradiol-17beta suppresses basal LH secretion. Oestradiol-17beta may act as an indicator of the follicular maturation, and the high plasma concentration of oestradiol-17beta noted from Day 3 to Day 4 may play an important role in determining the timing of initiation of the preovulatory gonadotrophin surge.

Animals↗

PubMed1997

Temporal changes in inhibin, steroid hormones, and steroidogenic enzymes during induced follicular atresia in the hypophysectomized cyclic hamster.

The time course for loss of ability of Graafian follicles to secrete inhibin and estradiol was investigated during induced follicular atresia. Cyclic hamsters were hypophysectomized on Day 1 (estrus) and injected s.c. with 30 IU eCG. Thereafter, these animals were given a single i.p. injection of antiserum to eCG on the morning of Day 4 to induce follicular atresia in a rapid and predictable manner. A drastic fall in plasma levels of estradiol and testosterone was noted within 1 h, whereas relatively high levels of plasma inhibin were maintained until 12 h, followed by an abrupt decline by 24 h. The first histological signs of pyknosis in granulosa cells appeared by 4 h, and breakdown of the mural granulosa layer was observed in most follicles by 8-12 h after immunoneutralization of circulating eCG. According to immunohistochemical analysis, inhibin activity was unchanged in granulosa cells at 12 h followed by a slight decline by 24 h, whereas positive reaction for aromatase in these cells rapidly declined by 8 h. Immunoreactivity of 17alpha-hydroxylase/C17,20-lyase (CYP 17) was also reduced in theca cells by 8 h. These results indicate that granulosa cells continue to secrete inhibin during the process of follicular atresia, although these cells quickly shut off the secretion of estradiol, and theca cells shut off the secretion of testosterone. The present results indicate as well that a rapid decline of estradiol and testosterone in plasma is an early sign of atresia in antral follicles. These results, therefore, suggest that the loss of enzymatic activity of aromatase in granulosa cells and CYP 17 in theca cells is a part of the process of follicular atresia.

Animals↗

PubMed1997

Contributions of endogenous inhibin and estradiol to the regulation of follicle-stimulating hormone and luteinizing hormone secretion in the pregnant rat.

To examine the contributions of endogenous inhibin and estradiol to the regulation of FSH and LH secretion in the pregnant rat, some rats were passively immunized against inhibin and/or estradiol, and others were ovariectomized, on Days 5, 10, 15, and 20 of pregnancy. Ovarian and uterine venous blood was collected separately to confirm the sources of inhibin and steroid hormones during pregnancy. Immunoreactivity of inhibin in the placenta was also examined by RIA. Levels of inhibin in ovarian venous plasma were significantly higher than those in peripheral plasma during pregnancy. No difference was observed between the levels of inhibin in uterine venous plasma and peripheral plasma. No immunoreactivity of inhibin was detected in placental homogenate from rats at Days 10, 15, and 20. FSH secretion significantly increased after immunoneutralization of inhibin during pregnancy. A marked increase in FSH secretion was noted on Days 5 and 20, and the smallest increase was observed on Day 15. Administration of estradiol antiserum (AS) alone did not induce a significant increase in FSH secretion on any day of pregnancy. However, a synergistic effect of estradiol AS and inhibin AS was observed on Day 20. On Days 5, 10, and 20, administration of inhibin AS or estradiol AS induced a significant increase in LH secretion. A synergistic effect of inhibin AS and estradiol AS on LH secretion was observed on Day 5. On Days 5 and 10, significantly high LH secretion was noted in ovariectomized rats as compared with that in rats treated with both inhibin AS and estradiol AS, indicating that other ovarian hormones such as progesterone may be involved in the suppression of LH secretion in these stages of pregnancy. These data indicate that both inhibin and estradiol, predominantly secreted from the ovary, are involved in the regulation of gonadotropin secretion during pregnancy as during the estrous cycle in the rat.

Animals↗

PubMed1997

Alterations to the pituitary-gonadal axis in the peripubertal female rat exposed in utero and through lactation to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The environmental pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin) is a potent disrupter of vertebrate endocrine systems. It was shown previously that in utero and lactational (IUL) exposure to TCDD resulted in a reduction in serum estradiol concentrations; however, the mechanism for this remains unknown. In the current study, the effects of perinatal exposure to TCDD on the pituitary-ovarian axis were examined. Pregnant rats were given a single oral dose of 1 microg TCDD/kg or vehicle as control on gestation Day 15, and female pups were killed on postnatal Day 21. Pituitaries were assayed for gonadotropin beta-subunit mRNA; additional pituitaries were cultured for 4 h and the media were assayed for FSH. Gonadotropin receptor mRNAs from vehicle- and TCDD-exposed animals were compared, with some ovaries cultured and the media assayed for estrogen secretion. LH, FSH, progesterone, and androstenedione concentrations were determined in serum. IUL exposure to TCDD resulted in a significant reduction of pituitary FSHbeta mRNA. Although estrogen output was shown to be reduced, neither serum FSH nor LH concentration was increased significantly, and FSH secretion in vitro was not altered. Similarly, serum progesterone and androstenedione were not altered by TCDD exposure, while in vitro estrogen secretion was significantly reduced. These data suggest that TCDD did not act on serum gonadotropin concentrations. The reduction in the concentration of serum estrogen appears to result from direct or indirect actions on the ovary at some point following androstenedione production.

Animals↗

PubMed1997

Ovarian response and FSH profile in cows following injection of various doses of inhibin antiserum.

Dose effect of inhibin antiserum on ovarian response and hormonal profiles were investigated. On day 12 of the estrous cycle (day 0 = estrus), 14 of 19 cows were given a single i.v. injection of 25 ml (n = 4), 37.5 ml (n = 5) or 50 ml (n = 5) antiserum against inhibin produced in a castrated male goat. The other 5 animals were given 50 ml castrated male goat serum (control serum). The animals in each group received a single i.m. injection of 0.5 mg prostaglandin F2 alpha analogue (PG) 48 hr following the serum injection. The population of follicles and ovulation rate (estimated by the number of corpora lutea) were examined by ultrasonography. Administration of inhibin antiserum consistently resulted in a significant (p < 0.01) increase in plasma concentrations of follicle-stimulating hormone (FSH) in inhibin-neutralized groups, although the increased FSH levels were sustained longer in 50-ml group than in the 25- and 37.5- ml groups. Levels in the circulating inhibin antibody titer were positively correlated with dosage of inhibin antiserum. A large number of antral follicles (> or = 4 mm in diameter) developed similarly after hypersecretion of FSH in all neutralized groups, coupled with a rise in plasma estradiol levels, while the number of large follicles (> or = 10 mm in diameter) on estrus showed a dose-dependent increase. Multiple ovulation (2 to 4) was recorded in all animals after injection of 50 ml inhibin antiserum, however all cows in the 25-ml group experienced only one ovulation and injection of 37.5 ml resulted in a variable number of ovulations (1 to 5). These results demonstrated that administration of inhibin antiserum on day 12, followed by injection of PG, was able to induce hypersecretion of FSH and subsequently multiple ovulations. The number of large follicles on estrus day and ovulations were affected by dosage of inhibin antiserum and were correlated with persistence of increased FSH levels or circulating antibody levels.

Animals↗

PubMed1997

Effects of repeated ether stress on the hypothalamic-pituitary-testes axis in adult rats with special reference to inhibin secretion.

Effects of ether stress on the hypothalamo-hypophysial-gonadal axis in adult male rats were examined. To clarify the role of adrenal glucocorticoids in gonadal function, the effects of adrenalectomy and Dexamethasone treatment were also investigated. Ether stress increased the plasma concentrations of ACTH and corticosterone, but decreased the plasma concentrations of LH, FSH, inhibin and testosterone. The pituitary responsiveness to LH-RH for LH release and testicular responsiveness to the endogenous LH for testosterone release were maintained in stressed rats. Adrenalectomy caused an increase in the plasma concentrations of ACTH, but decreased the plasma concentrations of LH, FSH and testosterone. Dexamethasone treatment in adrenalectomized rats recovered the levels of plasma gonadotropins to control levels. The concentration of plasma inhibin did not change in adrenalectomized rats, but it was decreased compared to control rats by Dexamethasone treatment. Treatments of Dexamethasone in intact male rats resulted in a decline in plasma levels of testosterone and inhibin without a decrease in the levels of LH and FSH, indicating the direct effect of Dexamethasone on the testes. These results indicate that increased ACTH secretion in stressed rats is probably due to hypersecretion of CRH from the hypothalamus, which suppresses gonadotropin secretion via the inhibition of LH-RH. The decreased levels of testosterone may be caused by a stress-induced decrease in plasma LH concentrations and increased secretion of corticosterone in the ether stressed rats. The low levels of plasma inhibin in stressed rats was also probably due to the direct effect of corticosterone on the Sertoli cells.

Adrenalectomy↗

PubMed1997

Adrenal and gonadal function in hypothyroid adult male rats.

The functional relationship between thyroid, adrenal and gonadal hormones was investigated using adult male rats. Hypothyroidism was produced by the administration of 4-methyl-2-thiouracil (thiouracil) in the drinking water for 2 weeks. Plasma concentrations of TSH dramatically increased, whereas plasma concentrations of tri-iodothyronine and thyroxine decreased in thiouraciltreated rats as compared with euthyroid rats. Hypothyroidism increased basal levels of plasma ACTH and pituitary content of ACTH. The pituitary responsiveness to CRH for ACTH release markedly increased, whereas the adrenal responsiveness to ACTH for corticosterone release decreased. These results indicated that hypothyroidism causes adrenal dysfunction in adult male rats. Pituitary contents of LH and prolactin decreased in hypothyroid rats as compared with euthyroid rats. In addition, hypothyroidism lowered pituitary LH responsiveness to LHRH. Testicular responsiveness to human chorionic gonadotrophin for testosterone release, however, was not different between euthyroid and hypothyroid animals. These results indicated that hypothyroidism causes adrenal dysfunction and results in hypersecretion of ACTH from the pituitary gland. Adrenal dysfunction may contribute to the inhibition of LHRH secretion from the hypothalamus, possibly mediated by excess CRH.

Adrenal Glands↗

PubMed1997

Ontogeny of inhibin secretion in the rat testis: secretion of inhibin-related proteins from fetal Leydig cells and of bioactive inhibin from Sertoli cells.

The ontogeny of inhibin secretion in the testis of rats was investigated. Testicular localization, content of immunoactive and bioactive inhibin and its molecular size in fetal and neonatal rats (from 16 days of gestation to 5 days of age) were determined. Strong immunostaining with an antiserum against a polypeptide of porcine inhibin alpha-subunit was noted in testicular interstitial cells from 16 days of gestation. Co-localization of inhibin alpha-subunit and 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) was observed in the interstitial cells until 2 days of age. Immunoreactive inhibin alpha-subunit in the interstitial tissue had disappeared by 5 days of age, although 3 beta HSD-positive cells were still detected. Weak immunostaining for the inhibin alpha-subunit was detected in the seminiferous tubules, probably in the cytoplasm of Sertoli cells, from 20 days of gestation onward. No inhibin alpha-subunit immunostaining was observed in germ cells throughout the experimental period. Testicular inhibin was detected at 16 days of gestation (49.5 +/- 6.7 pg per testis) by RIA. Testicular immunoreactive inhibin showed a tendency to increase during fetal life and levels were maintained at a similar value after birth (697.0 +/- 46.9 pg per testis at 5 days of age). Inhibin bioactivity and its molecular size in testicular homogenate was examined at 17 days of gestation and 0 and 5 days of age. Although no bioactivity was detected at 17 days of gestation, bioactivity was noted at 0 and 5 days of age (177.7 and 1303.9 pg per testis respectively). Immunoblot analysis with antiserum against inhibin alpha-subunit revealed only approximately 40 kDa molecular masses in the testis at 17 days of gestation, probably inhibin-related proteins, but not inhibin. At 0 and 5 days of age, a protein of 30 kDa molecular mass, possibly inhibin, was detected as well as material of approximately 40 kDa molecular mass. FSH in the plasma was first detected at 19 days of gestation (1197.0 ng/l), increased towards birth, and thereafter decreased (4588.5 +/- 572.3 ng/l at 21 days of gestation and 2400.0 +/- 179.6 ng/l at 5 days of age). These results indicate that Leydig cells in fetal and neonatal rats produce inhibin-related substances with no inhibin bioactivity, whereas Sertoli cells begin to produce inhibin during the perinatal period as a possible regulator of FSH secretion.

3-Hydroxysteroid Dehydrogenases↗

PubMed1996

High concentrations of immunoreactive inhibin in the plasma of mares and fetal gonads during the second half of pregnancy.

Plasma concentrations of immunoreactive (ir)-inhibin were measured in seven pregnant mares from around Day 140 of gestation to Day 2 after parturition using a heterologous bovine-based radioimmunoassay (RIA). Concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), oestradiol-17 beta, progesterone and relaxin were also measured in the same samples. A marked increase in plasma concentrations of ir-inhibin, FSH and LH occurred between Day 220 and Day 300 of gestation but the concentrations of all three hormones returned to baseline by about Day 320 (three weeks before parturition). In contrast, circulating concentrations of the three placental hormones, oestradiol-17 beta, progesterone and relaxin, increased during the final weeks of pregnancy and then decreased markedly to basal values within two days of parturition. There was a positive correlation between circulating concentrations of ir-inhibin and FSH (r = 0.75, P < 0.01) rather than the expected negative correlation. ir-inhibin was not detected in homogenates obtained at Day 190 of pregnancy and form term placenta, but high concentrations of ir-inhibin were present in homogenates of fetal and newborn gonads. Despite the high concentrations of ir-inhibin in these homogenates, they failed to exert any suppressive bioactivity on FSH secretion by rat pituitary cells cultured in vitro. Furthermore, immunohistochemical staining revealed the presence of inhibin in the interstitial cells of equine fetal gonads at Day 190 of gestation. These findings demonstrate for the first time that high concentrations of ir-inhibin, LH and FSH are secreted into the peripheral circulation of the mare during the second half of pregnancy. However, ir-inhibin present in the plasma of pregnant mares appears to be biologically inactive. This hormone is not presumed to be of placental origin but it is proposed that either the enlarged fetal gonads or the maternal ovaries, or both of these organs, may be a source of inhibin in response to the coincident increase in circulating concentrations of LH and FSH.

Animals↗

PubMed1996

Roles of inhibin and estradiol in the regulation of follicle-stimulating hormone and luteinizing hormone secretion during the estrous cycle of the rat.

The relative contributions of inhibin and estradiol in the regulation of FSH and LH secretion were examined at various stages of the estrous cycle in the rat. At 1100 h on metestrus, diestrus, or estrus or at 0500 h on proestrus, rats were ovariectomized or given an injection of normal goat serum, antiserum to inhibin (inhibin-AS), antiserum to estradiol (estradiol-AS), or both antisera to examine the role of gonadal hormones in the regulation of tonic gonadotropin secretion. Plasma samples were collected before and at 6, 12, and 24 h after the treatments. Further, to examine the effects of the treatments on preovulatory gonadotropin surges, the five treatments described were carried out at 0500 h on proestrus and blood samples were collected from 1100 h to 2000 h on the same day at 1.5-h intervals. There was a significant rise in the concentration of plasma FSH after injection of inhibin-AS as well as after ovariectomy on each day of the estrous cycle. These treatments, however, had less effect on estrous FSH secretion. The rise in FSH was greater with immunoneutralization against both inhibin and estradiol than with immunoneutralization against inhibin alone on diestrus and proestrus. Basal levels of LH were increased at all stages of the cycle through immunoneutralization against inhibin and were also increased through immunoneutralization against estradiol except at estrus. Especially on diestrus, a remarkable increase in LH secretion was induced at 6 h after immunoneutralization against both inhibin and estradiol (1449.3 +/- 100.3% vs. control). The magnitude of the LH surge increased in inhibin-immunized rats, decreased in estradiol-immunized or ovariectomized rats, and remained at normal levels after injections of both antisera. The magnitude of the primary FSH surge increased very markedly in the inhibin-immunized group and decreased in the estradiol-immunized group. These results suggest that both estradiol and inhibin play a role in the regulation of LH secretion and that inhibin is a major regulator of FSH secretion during the estrous cycle of the rat. Furthermore, it is suggested that one or more extragonadal factors suppress estrous FSH secretion.

Animals↗

PubMed1996

Induction of superovulation by immunoneutralization of endogenous inhibin through the increase in the secretion of follicle-stimulating hormone in the cyclic golden hamster.

The present study was conducted to study the effect of immunoneutralization against endogenous inhibin on FSH, LH, oestradiol-17 beta and progesterone secretion and to investigate the effect of removal of endogenous inhibin on subsequent follicular development in the hamster. After treatment with anti-inhibin serum (inhibin-AS) at 1100 h on day 2 of the oestrous cycle (day 1 = day of ovulation), a marked increase in plasma levels of FSH and a slight increase in plasma levels of LH were noted and pituitary contents of FSH, but not LH, were also increased. In the group treated with inhibin-AS, superovulation occurred on day 1 of the following cycle. Plasma levels of oestradiol-17 beta markedly increased with the increase in the number of ovulations induced by human chorionic gonadotrophin (hCG) as compared with those in control animals. In the second cycle, plasma concentrations and pituitary contents of FSH in the animals given 200 microliters inhibin-AS still showed high values as compared with those in the animals treated with control serum, although superovulation did not occur on day 1 of the third cycle. Plasma concentrations and pituitary contents of LH in the hamster given 200 microliters inhibin-AS tended to decrease as compared with those in control animals during the second cycle. Plasma concentrations of oestradiol-17 beta in the animals treated with 200 microliters inhibin-AS changed in a similar way to controls. A marked increase in plasma concentrations of progesterone was noted on days 1 and 2 of the second cycle in the group receiving inhibin-AS. The twice daily injection of 1 IU hCG during the second cycle to the animals given 200 microliters inhibin-AS induced superovulation on day 1 of the third cycle. These results indicate that circulating inhibin may be an important indicator of the number of developing follicles and may maintain the species-specific number of developing follicles through suppression of FSH secretion in the cyclic hamster. They also suggest that high levels of inhibin slightly suppress plasma levels of LH, indicating that plasma LH may also regulate follicular development in the cyclic hamster.

Animals↗

PubMed1995

Age-related increase in peptidylarginine deiminase in the male rat pituitary.

We have measured the activity of peptidylarginine deiminase (EC 3.5.3.15) in male Wistar rat pituitaries at various ages. Pituitaries obtained from 3- and 9-month-old rats showed negligible activities. The mean enzyme activity increased appreciably by 18 months and markedly by 24 months accompanied with actual increases in the enzyme content. The peptidylarginine deiminase mRNA content showed a similar but more gradual increase appreciable from 9 months. Many enzyme-positive cells were present in the pars distalis of 24-month-old male pituitaries. Most of the enzyme-positive cells coincided with lactotrophs. The pituitary prolactin content showed a gradually increasing profile resembling that of the enzyme mRNA, but the serum prolactin concentration did not increase significantly. Neither the serum 17 beta-estradiol content nor the pituitary estrogen receptor content showed significant variation that could account for the marked increase in the pituitary enzyme content between 18 and 24 months of age. These data suggest possible presence of other factors regulating the enzyme content in old male pituitaries.

Aging↗

PubMed1995

Superovulation of Holstein heifers by a single subcutaneous injection of FSH dissolved in polyvinylpyrrolidone.

This study was undertaken to determine whether a single injection of porcine FSH (pFSH) would induce a superovulatory response in cattle. Holstein heifers were given a single injection of pFSH (30 mg, s.c.) dissolved in saline (Group 1, n = 5); 50% polyvinylpyrrolidone (PVP; Group 2, n = 5); or 25% PVP (Group 3, n = 4). Group-4 heifers (n = 5) were given multiple intramuscular injections of pFSH every 12 h for 3 d at decreasing doses, for a total of 30 mg. All animals received a single injection of 750 microg PGF2 alpha 48 h after the initiation of pFSH treatment. Animals exhibiting estrus were artificially inseminated twice throughout estrus. Ova and embryos were recovered nonsurgically. Ovaries were examined by transrectal ultrasonography or by palpation per rectum on Day 7 or 8 of estrus. Plasma concentrations of pFSH, bovine FSH progesterone, estradiol-17 beta and inhibin were determined by specific radioimmunoassays. The number of corpora lutea (CL) and the numbers of total and transferable embryos which were detected and recovered in Groups 2 and 3 were equivalent to the numbers detected and recovered in Group 4. In Group 1, however, only 1 of 5 animals ovulated even a single oocyte. The present study demonstrated that only a single injection of pFSH dissolved in PVP was capable of inducing a superovulatory response by maintaining a high plasma FSH concentration to allow for the recovery of a sufficient number of embryos for transplantation.

Journal Article↗

PubMed1995

Effects of aluminum adjuvant on systemic reactions of lipopolysaccharides in swine.

In vivo effects of aluminum adjuvant on systemic reaction of bacterial lipopolysaccharide (LPS) in piglets were investigated. Intramuscular injection of 0.1 mg kg-1 of LPS added to aluminum hydroxide gel (LPS(+)AL) mitigated the leukopenia, trembling and serum levels of TNF-alpha and cortisol compared with the injection of LPS suspended in LPS-free saline (LPS(+)SALINE). The serum endotoxin levels were reduced remarkably but relatively long-lasting in the LPS(+)AL. The lethality in mice injected with LPS added to aluminum hydroxide gel was significantly reduced. Likewise, the Limulus activity of a test LPS was reduced by the addition of aluminum hydroxide gel or aluminum chloride.

Adjuvants, Immunologic↗

PubMed1995

Immunoneutralization of inhibin and estradiol during the follicular phase of the estrous cycle in cows.

To investigate the physiological importance of inhibin and estradiol in the regulation of FSH secretion during the follicular phase of the estrous-cycle in cows, animals were passively immunized against the two hormones. Sixteen cows were divided into four equal groups and given injections of prostaglandin F2 alpha (PG) i.m. twice at 8-h intervals on Day 10 of the estrous cycle (Day 0 = day of estrus) to induce luteal regression. At 48 h after the first PG injection, each group of four cows received injections of one of the following: 100 ml castrated goat serum (control serum), 100 ml antiserum against inhibin, 100 ml antiserum against estradiol, or a combination of 100 ml inhibin antiserum and 100 ml estradiol antiserum. The LH surge occurred within 2 days after injection of the control serum or inhibin antiserum, whereas it was not detected in either of the groups passively immunized against estradiol, indicating that passive immunization against estradiol blocks a positive feedback effect of estradiol on LH secretion. There was no clear difference in basal concentrations of LH among the four groups. Injection of the inhibin antiserum resulted in a marked increase (p < 0.01) in plasma concentrations of FSH compared with values in the control group, while there were no significant changes in concentrations of plasma FSH after injection of the estradiol antiserum. Combined administration of the inhibin and estradiol antisera also produced a marked increase (p < 0.01) in plasma concentrations of FSH. The FSH response to the combined immunization was longer in duration than the FSH response to immunization with inhibin alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Lipopolysaccharide-induced apoptosis in swine lymphocytes in vivo.

The in vivo effects of bacterial lipopolysaccharide (LPS) on the immune systems of piglets were investigated. Intravenous injection of 0.5 mg of LPS per kilogram of body weight induced apoptosis, which was characterized by nuclear chromatin condensation and fragmentation and a ladder formation of nucleosomal DNA in lymphocytes both in the cortex of the thymus and in the germinal centers and paracortical areas of mesenteric lymph nodes at 24 h postinjection. The levels of endotoxin, tumor necrosis factor alpha, and cortisol in serum increased, generally according to the dose of LPS. These findings suggest that LPS can induce in vivo apoptosis of lymphocytes in piglets and support the notion that cytokine and endocrine responses may play an important role in LPS-induced apoptosis in the immune system.

Animals↗

PubMed1995

Clinical manifestations associated with human herpesvirus 7 infection.

Twenty two cases of human herpesvirus 7 (HHV-7) infection are described. HHV-7 infection occurred later than human herpesvirus 6 (HHV-6) infection and induced exanthem subitum in 47.1% of the children. HHV-7 infection was associated with exanthem subitum and the other symptoms that were observed in HHV-6 infection.

Acute Disease↗