We have previously reported that tumor necrosis factor-alpha (TNF-alpha) suppressed pulsatile secretion of luteinizing hormone (LH) in adrenalectomized (ADX) rats, which was restored by replacement of glucocorticoid. In the present study, we examined the role of glucocorticoid in inducing the preovulatory LH surge under conditions of infectious stress. Intravenous injection of TNF-alpha (1 microg) into the proestrous rats at 1300 h attenuated the LH surge and decreased the number of oocytes ovulated. The inhibitory effect of TNF-alpha on the LH surge was blocked by pretreatment with indomethacin, suggesting that the effects of TNF-alpha were mediated by prostaglandins (PGs). On the other hand, ADX markedly enhanced the inhibitory effect of TNF-alpha on the LH surge and subsequent ovulation, which was almost completely restored by pretreatment with a subcutaneous injection of corticosterone (10 mg). These results suggest that glucocorticoid counteracts the inhibitory effect of the cytokines on the preovulatory LH surge by suppressing PG synthesis, and thereby helps to maintain reproductive function under infectious stress conditions.
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T Matsuwaki, M Suzuki, K Yamanouchi, and M Nishihara
H. Sugimoto, M. Suzuki, T. Takeuchi, and K. Ishikawa
To investigate the effect of cell density on rat somatotrophs, dispersed adult rat anterior pituitary cells were plated at several densities (0·6, 1·2, 2·4 and 6·0 × 105 cells/cm2) or at two densities (6·07 × 105 and 1·21 × 105 cells/cm2) as high and low densities respectively. A static incubation system was used to study the release of GH and peptidyl glycine α-amidating enzyme (PAM; a component of secretory granules) and the cellular concentration of cyclic AMP (cAMP) in basal and stimulated cells. In addition, a perifusion system was used to characterize the sensitivity to GH-releasing factor (GRF) at both high and low densities. The high density of cells in both the static incubation and perifusion systems caused a low basal secretion rate of GH and PAM. When the cultured cells were stimulated with human GRF (hGRF) in perifusion, GH secretion from cells at high density was markedly higher than that from cells at low density. The cAMP content in the static incubation system showed a similar tendency to that observed for basal and stimulated GH secretion; that is, the basal cAMP content was increased as the cell density decreased. The cellular concentration of cAMP was increased by about threefold by 1 nmol hGFR/1 and by more than tenfold by 10 nmol hGRF/1. When the medium from cells cultured at low density was replaced by that from the cells at high density, there was no change in the basal cellular cAMP content of the cells at low density. These data suggest that cell-to-cell contact in dispersed pituitary cells seems to be important in the maintenance of their cellular integrity to secrete GH.
Journal of Endocrinology (1991) 131, 237–244
H. Takeda, M. Suzuki, I. Lasnitzki, and T. Mizuno
The testicular feminization (Tfm) locus, which produces a deficiency in androgen receptors, is located on the X-chromosome. Steroid autoradiographic techniques were used to demonstrate the mosaicism of the X-chromosome inactivation in two androgen target tissues of X Tfm /X+ heterozygous female mice.
In the mesenchyme of urogenital sinuses of wild-type female fetuses (X+/X+), more than 95% of the cells were androgen-receptor positive (labelled with [3H]testosterone) while in that of heterozygous fetuses (X Tfm /X+), about half of the cells were receptor positive (Tfm gene inactive). Statistical analysis of coherent clone size was applied to the heterozygous mesenchyme of the urogenital sinus and the coherent clone size of receptor-positive cells was estimated to be two or three cells per clone. This small clone size suggests that considerable cell mixing occurred in the tissue during embryonic development.
Androgen binding in the mammary gland rudiments was restricted to the mesenchymal cells only in close vicinity to the epithelial mammary bud. In the wild-type rudiments most of the mesenchymal cells beneath the epithelium were receptor positive, while in heterozygous rudiments, receptor-positive and -negative cells intermingled. This observation suggests that in the wild-type mammary gland rudiments the epithelial bud may induce the formation of androgen receptors in adjacent mesenchymal cells rather than attract pre-existing receptor-rich mesenchymal cells.
J. Endocr. (1987) 114, 125–129
T Okamoto, K Matsuo, R Niu, M Osawa, and H Suzuki
The present study was undertaken to investigate whether human chorionic gonadotropin (hCG) beta-core fragment (hCG beta cf) was directly produced by gestational trophoblastic tumors. Immunoreactivity of hCG beta cf was demonstrated in the extracts as well as in the culture media of hydatidiform mole tissues. It was also present in the extracts of choriocarcinoma tissues, and its molar concentration exceeded that of intact hCG. The presence of hCG beta cf was then confirmed by gel chromatography and Western blot analysis. Immunohistochemistry showed localization of hCG beta cf immunoreactivity to the syncytiotrophoblasts and scattered cells in the stroma of mole tissue, and to syncytiotrophoblastic cells in choriocarcinoma. Immunoreactivity of hCG beta cf was also detected in the sera of the patients with gestational trophoblastic disease, although the hCG beta cf/hCG ratio was less than one hundredth of that in the tissue extracts. Serial measurement of serum hCG beta cf levels after mole evacuation showed that they declined much more rapidly than those of hCG and became undetectable in the patients with subsequent spontaneous resolution, while hCG beta cf remained or became detectable before the rise of hCG was observed in the patients with subsequent persistent trophoblastic disease. Taken together, these results suggest that hCG beta cf is directly produced by gestational trophoblastic tumors, and monitoring of hCG beta cf in the serum after mole evacuation may be useful for early prediction of subsequent development of postmolar persistent trophoblastic disease.
T Adachi, M Inoue, H Hara, E Maehata, and S Suzuki
Extracellular-superoxide dismutase (EC-SOD) is a secretory glycoprotein located in blood vessel walls at high levels and may be important in the antioxidant capability of vascular walls. The aim of this study was to assess plasma levels of EC-SOD and to evaluate the relationship of the EC-SOD level with insulin resistance in type 2 diabetic patients. We determined plasma EC-SOD in 122 patients and found for the first time that the EC-SOD level was strongly and positively related to adiponectin (r=0.503, P < 0.001), and significantly and inversely related to fasting plasma glucose (FPG) (r=-0.209, P=0.022), body-mass index (BMI) (r=-0.187, P=0.040) and homeostasis model assessment-insulin resistance index (HOMA-R) (r=-0.190, P=0.039). Stepwise-multiple regression analysis also showed a significant influence of adiponectin (F=33.27) on the EC-SOD level. Administration of pioglitazone to 19 diabetic patients significantly increased the plasma levels of EC-SOD (69.9+/-19.3 ng/ml to 97.4+/-25.9 ng/ml; P < 0.0001) and adiponectin, while it decreased tumor necrosis factor-alpha (TNF-alpha). The present observations suggest that factors related to the pathogenesis of insulin resistance play an important role in the regulation of the plasma EC-SOD concentration. It is possible that the increase in the EC-SOD level by pioglitazone administration in diabetic patients is due to a decline of TNF-alpha, which is known to suppress EC-SOD expression.
GW Sun, H Kobayashi, M Suzuki, N Kanayama, and T Terao
Link protein (LP), an extracellular matrix protein in cartilage, stabilizes aggregates of hyaluronic acid (HA) and proteoglycans, including aggrecan and inter-alpha-trypsin inhibitor (ITI). We have shown previously that cartilage LP is present in the maturing rat and mouse ovary. In the present study, we have employed immunohistochemistry to examine the anatomical distribution of cartilage LP in the human ovary. The expression of cartilage LP was selectively detected in the cells within the granulosa compartment of the preovulatory dominant follicle. The HA-positive granulosa-lutein cells were found to be a cartilage LP-positive subpopulation. We subsequently studied the in vitro expression of cartilage LP in cultured human granulosa-lutein cells obtained at oocyte retrieval for in vitro fertilization. Analysis of cultured cells by enzyme-linked immunoaffinity assay, Western blotting and immunofluorescence microscopy revealed that gonadotropin stimulates cartilage LP production. Time-course studies indicated that the cartilage LP production was induced as early as with gonadotropin stimulation for 2 h, and the effect was sustained up to 8 h. Western blot analysis further revealed the presence of the macroaggregates composed of HA, ITI and cartilage LP in the gonadotropin-stimulated granulosa-lutein cell extracts. Collectively, the present results raise the possibility that cartilage LP forms extracellular structures that may have a regulatory function in the developing follicle in the human ovary.
M. A. Ghatei, K. Takahashi, Y. Suzuki, J. Gardiner, P. M. Jones, and S. R. Bloom
The distribution of a novel neuropeptide, pituitary adenylate cyclase-activating polypeptide (PACAP), was studied in the brain of the rat and man and a variety of other rat tissues using Northern blot hybridization and two radioimmunoassays for PACAP 1–38 and PACAP 1–27. The assay, using PACAP 1–38 as standard and an antibody to PACAP 21–38 and radiolabelled tracer, revealed immunoreactive PACAP in all brain regions examined, with the highest concentrations in the rat being in the hypothalamus, nucleus accumbens and substantia nigra (380 ± 34, 310 ± 37 and 346 ± 30 pmol/g wet tissue, means±s.e.m., n = 5 respectively), whilst in man the highest concentrations were found in the pituitary gland (15·8 ± 4·7 pmol/g). Immunoreactive PACAP 1–38 was also detected in the rat gastrointestinal tract, adrenal gland and testis. The assay using PACAP 1–27 as standard and label and an antibody to PACAP 1–27 detected immunoreactive PACAP only in the rat hypothalamus (12·6 ± 1·8 pmol/g wet tissue, n = 5). PACAP mRNA of approximately 2·7 kb in size was detectable in all brain regions of both rat and man, and its distribution paralleled that of the immunoreactive peptide.
Gel permeation chromatography of different regions of human and rat hypothalamus, and also rat spinal cord and small intestine, showed a broad immunoreactive peak corresponding to PACAP 1–38. Fast protein liquid chromatography (FPLC) resolved this peak into two immunoreactive peaks, the majority eluting in the position of synthetic PACAP 1–38. Presence of immunoreactivity corresponding to PACAP 1–27 was also confirmed in rat hypothalamic extracts using FPLC. The presence of immunoreactive PACAP and its precursor encoding mRNA in various neural and other tissues is in accord with a role for PACAP as a neurotransmitter, neuromodulator or neurohormone.
Journal of Endocrinology (1993) 136, 159–166
K Ichikawa, T Miyamoto, T Kakizawa, S Suzuki, A Kaneko, J Mori, M Hara, M Kumagai, T Takeda, and K Hashizume
The thyromimetic compound SK&F L-94901 shows more potent thyromimetic activity in the liver than in the pituitary gland or heart when administered to rats. The mechanisms of liver-selectivity of SK&F L-94901 were examined using cultured rat hepatoma cells (dRLH-84) and rat pituitary tumor cells (GH3), both of which showed saturable cellular uptake of tri-iodothyronine (T(3)). When isolated nuclei with partial disruption of the outer nuclear membrane were used, SK L-94901 competed for [(125)I]T(3) binding to nuclear receptors almost equally in dRLH-84 and GH3 cells. SK L-94901 also did not discriminate thyroid hormone receptors (TR) alpha1 and beta1 in terms of binding affinity and activation of the thyroid hormone responsive element. In intact cells, however, SK L-94901 was a more potent inhibitor of nuclear [(125)I]T(3) binding in dRLH-84 cells than in GH3 cells at an early phase of the nuclear uptake process and after binding equilibrium. These data suggest that SK L-94901 is more effectively transported to nuclear TRs in hepatic cells than in pituitary cells and therefore shows liver-selective thyromimetic activity. In conclusion, SK L-94901 discriminates hepatic cells and pituitary cells at the nuclear transport process. The cellular transporters responsible for this discrimination were not evident.
T Takeda, K Ichikawa, M Kobayashi, T Miyamoto, S Suzuki, Y Nishii, A Sakurai, T Nagasawa, M Katai, K Nakajima, and K Hashizume
In order to study whether peripheral action of thyroid hormones is altered in insulin deficiency and to elucidate the biological consequences of alteration of the cytosolic 3,5,3′-tri-iodo-l-thyronine (T3) binding protein (CTBP), we measured malic enzyme, T3-responsive nuclear n protein, CTBP and nuclear thyroid hormone receptor in the liver and kidney of streptozotocin (STZ)-induced diabetic rats that were treated with or without insulin and/or a receptor-saturating dose of T3. The following results were obtained. 1. Induction of malic enzyme by T3 was apparently diminished in diabetic rats. However, supplementary injection of insulin enabled previously given T3 to take effect in diabetic rats. 2. T3-responsiveness of other hepatic proteins (n protein and CTBP) was not altered by insulin in diabetic rats. 3. The level of n protein was increased by insulin in diabetic rats in vivo and in perfused rat liver, indicating that the hepatic n protein is a novel insulin-responsive protein. T3 and insulin increased the level of n protein non-synergistically in diabetic rat liver. 4. Hepatic nuclear receptor levels were not altered in diabetic rats. 5. Hepatic CTBP levels were decreased in diabetic rats. This was not due to the toxic effect of STZ. Low CTBP level was only partially increased by insulin after 30 days of diabetic period. Renal CTBP levels were not altered in diabetic rats with or without insulin treatment. These results indicate that reduction of CTBP did not influence the hepatic response to a receptor-saturating dose of T3, although CTBP may regulate the nuclear T3 transport, and that fundamental action of a receptor-saturating dose of T3 was not attenuated in diabetic rat liver.
Journal of Endocrinology (1994) 143, 55–63
H. Suzuki, A. S. Tischler, N. D. Christofides, M. Chretien, N. G. Seidah, J. M. Polak, and S. R. Bloom
High concentrations of a novel pituitary protein (7B2) have been shown to be present in the PC12 rat phaeochromocytoma cell line by radioimmunoassay. 7B2-like immunoreactivity (IR-7B2) was released from PC12 cells into the incubation medium in response to stimulation by a depolarizing concentration of K+, and this K+-evoked release was inhibited by Co2+, The major IR-7B2 in PC12 cell and medium appeared to be identical to that in porcine pituitary gland as judged by both gel permeation chromatography and by reverse-phase high performance liquid chromatography (HPLC). Gel permeation chromatography of extracts of cell and medium revealed two IR-7B2 peaks, the earlier eluting at a elution coefficient (K av) of 0·30 and the later at a K av of 0·54. In medium, over 90% of the IR-7B2 eluted as the earlier peak. Fractionation of extracts of cell and medium on reverse-phase HPLC showed three main IR-7B2 peaks eluting at 43, 44·5 and 46% acetonitrile/water with 0·1% trifluoroacetic acid. The findings suggest that IR-7B2 might be released by calcium-mediated exocytosis.
J. Endocr. (1986) 108, 151–155