Tsuneko Onouchi

Effect of soy protein on bone metabolism in postmenopausal Japanese women.

Abstract: We conducted a cross-sectional study of the effects of soybean protein intake on bone mineral density and biochemical markers in 85 postmenopausal Japanese women. Nutrients in the diet of postmenopausal Japanese women visiting the osteoporosis unit, including subjects with normal lumbar spine bone mineral density (L2–4 BMD), were investigated by questionnaire, and the calculated daily energy, protein, soy protein and calcium intake were obtained. L2–4 BMD was measured with dual-energy X-ray absorptiometry, and assays done of serum alkaline phosphatase (ALP) and serum intact osteocalcin (IOC) as bone formation markers and urinary pyridinoline (UPYR) and urinary deoxypyridinoline (UDPYR) as bone resorption markers. Soy protein intake was significantly associated with the Z-score for L2–4 BMD (r= 0.23, p = 0.038) and UDPYR (r =−0.23, p = 0.034). Stepwise multiple regression analyses showed that soy protein intake is significantly associated with the Z-score for L2–4 BMD (β= 0.225, p = 0.04) and UDPYR (β=−0.08, p = 0.03) among four nutritional factors. These results suggest that high soy protein intake is associated with a higher bone mineral density and a lower level of bone resorption, but further studies are needed to confirm the causal dynamic mechanisms.

Hypothalamic and hypophysial progesterone receptors: Estrogen-priming effect, differential localization, 5α-dihydroprogesterone binding, and nuclear receptors

Abstract Specific progesterone receptor of 7 S which can be isolated from rat female hypothalamic and hypophysial cytosols was further investigated in terms of its induction effects by estrogen-priming, intracerebral localization, 5α-dihydroprogesterone (DHP) binding, and nuclear receptors. Estrogen-priming was necessary for the appearance of the cytosol receptors. The 7 S hypothalamic and hypophysial receptors were increased in a dose dependent fashion by estradiol injections. The maximal effective doses of estradiol benzoate for both tissues were 1 and 10 μg, respectively. The receptors were mostly localized in the median eminence, preoptic-anterior hypothalamus and anterior hypophysis of estrogen-primed immature and mature rats, but little or no 7 S binding was detected in the cerebral cortex, reticular formation, amygdaloid complex and posterior hypophysis. This differential localization of progesterone receptors resembles that of estrogen receptors, suggesting possible induction of progesterone receptors in these specific brain regions by estrogen. Progesterone receptor complexes of 5 S were isolated from “purified” nuclei of anterior pituitaries from estrogen-primed adult female rats. These results on the cytosol and nuclear receptors suggest that progesterone can directly act on the brain through its interaction with specific progesterone receptors in the hypothalamus and hypophysis. It is noteworthy that 5α-DHP can bind the progesterone receptors in both tissues, suggesting its direct feedback action on the brain through the receptors.

Urocortin 1 reduces food intake and ghrelin secretion via CRF2 receptors

Although it is known that urocortin 1 (UCN) acts on both corticotropin-releasing factor receptors (CRF(1) and CRF(2)), the mechanisms underlying UCN-induced anorexia remain unclear. In contrast, ghrelin, the endogenous ligand for the growth hormone secretagogue receptor, stimulates food intake. In the present study, we examined the effects of CRF(1) and CRF(2) receptor antagonists (CRF(1)a and CRF(2)a) on ghrelin secretion and synthesis, c-fos mRNA expression in the caudal brain stem, and food intake following intracerebroventricular administration of UCN. Eight-week-old, male Sprague-Dawley rats were used after 24-h food deprivation. Acylated and des-acylated ghrelin levels were measured by enzyme-linked immunosorbent assay. The mRNA expressions of preproghrelin and c-fos were measured by real-time RT-PCR. The present study provided the following important insights into the mechanisms underlying the anorectic effects of UCN: 1) UCN increased acylated and des-acylated ghrelin levels in the gastric body and decreased their levels in the plasma; 2) UCN decreased preproghrelin mRNA levels in the gastric body; 3) UCN-induced reduction of plasma ghrelin and food intake were restored by CRF(2)a but not CRF(1)a; 4) UCN-induced increase of c-fos mRNA levels in the caudal brain stem containing the nucleus of the solitary tract (NTS) was inhibited by CRF(2)a; and 5) UCN-induced reduction of food intake was restored by exogenous ghrelin and rikkunshito, an endogenous ghrelin secretion regulator. Thus, UCN increases neuronal activation in the caudal brain stem containing NTS via CRF(2) receptors, which may be related to UCN-induced inhibition of both ghrelin secretion and food intake.

A Strategy for the Management of Elderly Women with Primary Hyperparathyroidism: A Comparison of Etidronate Therapy with Parathyroidectomy

Objective: To evaluate the efficacy of etidronate (EHDP) on lumbar spine bone mineral density (LSBMD) and total bone mineral density (TBMD) in elderly women with primary hyperparathyroidism (PHPT), we compared changes in LSBMD and TBMD between patients treated by EHDP therapy and parathyroidectomy (PTX). Subjects and Methods: Twenty-two PHPT patients were enrolled and randomized into two groups; 9 received EHDP and 13 underwent PTX. All patients were followed up for 1 year by measuring LSBMD, TBMD, serum calcium, inorganic phosphate, parathyroid hormone, 1,25-dihydroxyvitamin D, serum alkaline phosphatase, intact osteocalcin, urinary pyridinoline (Upyd) and urinary deoxypyridinoline (Udpd). The presence of spinal fractures was evaluated by X-ray photography before and after treatment. Results: EHDP treatment produced a significant increase in LSBMD of 10% compared with pretreatment levels after 1 year (p < 0.03, compared to baseline), while PTX produced a significant increase in LSBMD of 20% compared to pretreatment levels (p < 0.01). However, TBMD remained unchanged for 1 year after both EHDP administration and PTX. Among biochemical bone turnover markers, EHDP administration resulted in significant decreases in alkaline phosphatase by 78%, Upyd by 64% and Udpd by 37% after 12 months compared with the pretreatment levels (p < 0.05) and intact osteocalcin by 67% after 6 months (p < 0.05). There were no differences in the fracture rate between the EHDP and PTX groups during 1 year. Conclusion: EHDP administration results in a somewhat lower increase in LSBMD than that following PTX and suppresses bone formation and resorption in elderly PHPT patients for 1 year. We conclude that PTX is preferable to EHDP therapy for the management of elderly PHPT patients; however, EHDP administration should also be considered for elderly patients with many complications or who are unfit for surgery.

Impaired gamma carboxylation of osteocalcin in elderly women with type II diabetes mellitus: relationship between increase in undercarboxylated osteocalcin levels and low bone mineral density

We conducted a cross-sectional examination of the role of serum vitamin K levels as they relate to bone metabolism in elderly women with type II diabetes mellitus (DM). Eighty-five elderly women with type II DM were enrolled. Three fractions of vitamin K, phylloquinone (PK), menaquinone 4 (menatetrenone; MK 4), and menaquinone 7 (MK 7), along with undercarboxylated osteocalcin (UcOC), intact osteocalcin (IOC), urinary deoxypyridinoline (udpd), urinary type I collagen N-telopeptide (NTx), and intact parathyroid hormone (IPTH) were measured. Bone mineral density was measured in the lumbar spine (LSBMD) by dual-energy X-ray absorptiometry (DXA), and T scores or Z scores were calculated. The patients were divided into two groups by T score, under −2.5 (osteoporotic group) and over −2.5 (non-osteoporotic group). UcOC levels in osteoporotics patients were significantly higher than those in the non-osteoporotic group (3.09 ± 3.94 vs 1.82 ± 1.76 ng/ml, P = 0.02). The correlation between Z score and logarithmic UcOC/IOC levels in type II DM showed a negative trend (P = 0.07) and a significantly and negatively association with logarithmic NTx (r = −0.38; P = 0.001). In osteoporotic DM, the UcOC/IOC ratio was significantly correlated with the Z score (r = −0.61; P ≪ 0.05). Furthermore, logarithmic UcOC/IOC showed a negative correlation with logarithmic MK 7 (r = −0.50; P = 0.001). In conclusion, the reduction in LSBMD in elderly women with type II DM may be associated, in part, with a defect in Γ-glutamylcarboxylation by vitamin K.

Progesterone Receptors in the Cerebral Cortex of Neonatal Female Rats

Progestin-binding components were detected in cerebral cortical cytosols from female rats at 7 days of age. These components labeled in vitro with a tritiated synthetic progestin. R5020, sediment in the 7S region in sucrose density gradients containing 10% glycerol. The dissociation constants and the number of binding sites of the components were 3.9 X 10(-10)M and 47.5 fmol/mg cytosol protein, respectively, indicating high affinity and low capacity binding. The 7S-binding components were specific for progestational compounds. Estradiol competed weakly. Incubation with pronase abolished the 7S progestin binding. Heat experiments suggested a thermolabile nature of the components. These results suggest that the cytosols from the cerebral cortex of 7-day-old female rats contain progesterone receptors.

Implications of Measuring Soluble Receptor Activators of Nuclear Factor-κB Ligand and Osteoprotegerin in Bone Metabolism of Elderly Women

Background/Aim: The discovery of a signaling system consisting of a soluble receptor activator of the NF-κB ligand (sRANKL) and its decoy receptor osteoprotegerin (OPG) has provided a valuable key to understanding the pathophysiology of the bone microenvironment. We conducted a cross-sectional study of the role of sRANKL and OPG levels as they relate to bone metabolism in elderly postmenopausal women with and without osteoporosis. Subjects and Methods: Fifty-one elderly women with or without osteoporosis were enrolled in the study. Bone alkaline phosphatase, osteocalcin, urinary deoxypyridinoline and urinary type I collagen N-terminal telopeptide (NTx) were measured as bone metabolic markers. Serum levels of OPG and sRANKL were measured by sandwich enzyme-linked immunosorbent assay and the lumbar spine bone mineral density (LSBMD) with dual-energy X-ray absorptiometry. Furthermore, we compared the sRANKL and OPG levels in elderly women with and without vertebral fractures (VFs). Results: In elderly postmenopausal women, there was a significant positive association between OPG levels and the T score and Z score of LSBMD (r = 0.345 and p = 0.014 for T score; r = 0.438 and p = 0.001 for Z score). sRANKL levels were not significantly correlated with T score, Z score of LSBMD, or any of the four bone metabolic markers. There were no significant differences in the sRANKL levels among the three groups (normal bone mineral density, osteopenia, and osteoporosis), but a trend toward a higher value in the osteoporosis group. The sRANKL/OPG ratio was negatively correlated with the T score and Z score of LSBMD (r = –0.336, p = 0.017; r = –0.384, p = 0.006, respectively), but not with any of the four bone metabolic markers. OPG levels in elderly women with VFs were lower than in those without VFs (p = 0.05). Multiple regression analysis showed that OPG and NTx are contributing factors to bone loss in elderly women (p = 0.014 and 0.012, respectively). Conclusion: The OPG level provides a good predictor of osteoporosis as well as NTx in elderly women; additionally, the findings suggest that OPG might protect elderly women from bone loss or fractures.

Apelin-12 stimulates acid secretion through an increase of histamine release in rat stomachs

BACKGROUND Apelin is a peptide that was originally isolated from bovine stomach extract and has been demonstrated to be an endogenous ligand for orphan receptor APJ. Both apelin and the APJ receptor are widely distributed in the whole body. Apelin is supposed to have important regulatory roles in the function of many organs such as in the cardiovascular system; however, the mechanism of apelin function has not been elucidated. In this study, we studied the action of apelin in acid secretion and demonstrated its mechanism of action. METHODS Gastric lumen-perfused rats were prepared and their stomachs were perfused with a saline solution using a peristaltic pump. Apelin-12, 36 or Pyr(1)-apelin-13, were intravenously injected to examine their effects on acid secretion in rats. In some experiments, rats were pretreated with famotidine (0.33 mg/kg) or atropine sulfate (0.1mg/kg) intravenously injected 5 or 15 min before apelin injection. Furthermore, isolated vascularly perfused rat stomachs were prepared to examine the effect of apelin on histamine release, which was assayed in the effluent by radioimmunoassay. Messenger RNA of histidine decarboxylase (HDC) in gastric mucosa of isolated stomach was measured by real-time RT-PCR. RESULTS Apelin-12 (20-100 μg/kg) dose-dependently increased gastric acid secretion, with a maximum of 203% at 100 μg/kg (n=5). Neither Pyr(1)-apelin-13 nor apelin-36 caused a significant increase in acid secretion. Famotidine completely blocked the stimulatory action of apelin on acid secretion. Apelin-12 (100 μg/20 ml/10 min) markedly increased histamine release from isolated vascularly perfused rat stomachs by 278%, and also increased the mRNA of HDC by 480% of the control. Atropine sulfate did not abolish the effect of apelin on the secretion of gastric acid. Apelin-12 amplified an increase of acid secretion stimulated by gastrin injection. CONCLUSION These results indicate that apelin-12 stimulates gastric acid secretion through an increase in histamine release and synthesis from gastric mucosa, suggesting that apelin might play a role in the secretion of gastric acid or serve as a regulating factor of the secretion of gastric acid.

The presence of progesterone receptors in the sexual skin of the monkey

R5020(17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione)-binding components with sedimentation coefficient of 8S were detected in sexual skin cytosols from estrogen-primed ovariectomized Japanese monkey (Macaca fuscata fuscata). In contrast, little 8S binding was found in similar preparations from the abdominal skin. The dissociation constants and the number of binding sites of the components were 1.6 x 10(-10)M and 36 fmoles/mg cytosol protein, respectively. The 8S binding components were specific for progestational compounds. Incubation with pronase abolished the 8S binding. Thermal experiments revealed the thermolabile nature of the components. Moreover, the concentration of the R5020-binding components was markedly increased by estradiol-17 beta 3-benzoate injections. We conclude from these results that the cytosols from the sexual skin of estrogen-primed female monkeys contain progesterone receptors.

Effects of Ovarian Steroid Hormones on the Brain and Hypophysis Receptor Modulation and Chromatin Binding

Progesterone plays a role in the central nervous system as a facilitator and inhibitor of sexual behavior and gonadotropin release in rodents. Estrogen-induced gonadotropin surges in female rats can be facilitated or inhibited by progesterone in the cycling rats (Everett, 1948; Zeilmaker, 1966; Brown-Grant et al., 1972; Brown-Grant and Naftolin, 1972), and also be mimicked in the estrogen-treated ovariectomized rats by administration of progesterone (Caligaris et al., 1971; Freeman et al., 1976; Goodman, 1978), and in estrogen-treated prepubertal female rats of 28 days of age (Attardi, 1981). The effects of progesterone on sexual behavior in estrogen-primed female rats are also well-demonstrated (Meyerson, 1972; Feder and Marrone, 1977).