Total and regional bone mineral content in normal premenopausal women

In the present, cross-section study, a total of 185 normal premenopausal females--aged 15 through 19 years (n = 40), 20 to 29 years (n = 60), 30 through 39 years (n = 40) and 40 to 49 years (n = 45)--were assessed in order to observe and evaluate the total body bone mineral content and the regional body mineral content of different anatomical regions (head, trunk, arms and legs), when the bone mass peak is established in women and its course during premenopause. All subjects underwent bone densitometry with dual energy X-ray absorptiometry with a Norland XR-26 bone densitometer. No differences between groups were found in total body bone mineral and regional bone mineral content values. Total body bone mineral values (mean +/- SD) were 2546 +/- 461 g and 2691 +/- 499 g in the 15-19 year-old group and 40-49 year-old group respectively. The regional bone mineral content values for the same age group were 495 +/- 75 g and 499 +/- 89 g for the head, 1007 +/- 254 g and 1043 +/- 212 g for the trunk, 327 +/- 74 g and 336 +/- 81 for the arms, and 860 +/- 167 g and 811 +/- 146 g for the legs. The results of this study indicate that the peak bone mass is reached at the age of 20 years and that it remains stable in the premenopausal eugonadal females.

Endocrine- and autocrine-mediated regulation of rat ovarian (theca-interstitial) interleukin-1 beta gene expression: gonadotropin-dependent preovulatory acquisition

We, and others have recently demonstrated the ovary to be a site of interleukin-1 (IL-1) reception and action. Since IL-1 is an established mediator of inflammation and since ovulation may constitute an inflammatory-like reaction, consideration was given to the possibility that IL-1 may play an intermediary role in the ovulatory process. To begin to evaluate the above hypothesis, we have set out to evaluate rat ovarian IL-1 beta gene expression, to determine its cellular localization, and to study its modulation by key endocrine and autocrine regulatory signals. To this end, use was made of a solution hybridization/RNase protection assay in which rat ovarian total RNA (20 micrograms) was hybridized with a [32P]-labeled 272 base rat IL-1 beta antisense riboprobe. To assess rat ovarian IL-1 beta gene expression under in vivo circumstances, use was made of an established experimental model capable of simulating naturally-occurring follicular maturation, ovulation, and corpus luteum formation. Specifically, a single subcutaneous injection of PMSG (15IU/rat) was followed (48h) later by an ovulatory dose (15IU) of human chorionic gonadotropin (hCG). A faint protected fragment 222 bases long corresponding to the IL-1 beta message was detectable in whole ovarian material prior to gonadotropic stimulation. Treatment with PMSG for 48h resulted in a modest, albeit measurable increase in the densitometrically-quantified steady state levels of the ovarian IL-1 beta message. Most striking, however, were the increments noted in the relative abundance of ovarian IL-1 beta transcripts following a 6h exposure to hCG producing a 4 to 5-fold increase (P less than 0.05) over the untreated state at a time point approximately 6h prior to projected follicular rupture. Subsequent evaluation of ovarian IL-1 beta transcripts, 24 and 48h following hCG administration, revealed significant (P less than 0.05) decrements (relative to the 6h peak) to a level comparable to that seen at the conclusion of 48h of treatment with PMSG. Cellular localization studies revealed the gonadotropin-dependent IL-1 beta mRNA to be theca-interstitial cell-exclusive. To assess rat ovarian IL-1 beta gene expression under in vitro circumstances, we have set out to determine whether IL-1 itself may influence the relative level of its own message. Treatment of whole ovarian dispersates with rhIL-1 beta (10ng/ml) for 4 and 24h resulted in a marked (P less than 0.05) time-dependent increase (up to 12-fold) in the relative abundance of IL-1 beta transcripts when compared with untreated controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Insulin-like growth factor receptor gene expression in the rat ovary: divergent regulation of distinct receptor species

The intraovarian insulin-like growth factor (IGF) system constitutes a triad composed of ligands, receptors, and binding proteins. Although conventional radioligand receptor assays have documented the presence of specific receptors for insulin and insulin-like peptides in some rat somatic ovarian cell types, the exact cellular localization and hormonal regulation of the receptors in question remain matters of inquiry. To reevaluate the very presence, cellular localization, and hormonal regulation of the IGF receptor gene family in the rat ovary, solution hybridization/RNase protection assays were used wherein ovarian total RNA (20 micrograms) from immature (21-23 days old) rats was hybridized with 32P-labeled type I IGF receptor, type II IGF/mannose-6-phosphate receptor, and insulin receptor riboprobes. Single protected fragments 261 (type I IGF receptor), 500 (type II IGF/mannose-6-phosphate receptor), and 478 (insulin receptor) bases long were evident in whole ovary, granulosa, and theca-interstitial cells. Hypophysectomy of immature rats led to significant (P less than 0.05) albeit variable decrements in the relative (densitometrically quantified) ovarian abundance of transcripts corresponding to the type I IGF (but not insulin or type II IGF/mannose-6-phosphate) receptor. Treatment of immature hypophysectomized rats with FSH (10 micrograms/rat.day x 2.5 days) resulted in a significant (P less than 0.05) increase (4-fold) in transcripts corresponding to the type I IGF receptor in both whole ovarian material and freshly isolated granulosa cells. Similar (3.7-fold) increments (P less than 0.05) were noted after treatment with a diethylstilbestrol-containing sc silastic implant applied for a total of 5 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-like growth factors: the ovarian connection

A large body of information now supports the existence of a complete intraovarian insulin-like growth factor (IGF) system replete with ligands, receptors, and binding proteins. Although much remains to be learned, the emerging consensus would suggest that the intraovarian IGF system is concerned largely with the amplification of gonadotrophin hormonal action for the facilitation of follicular growth and development. Future studies are likely to address the central issue of indispensability and the documentation of a meaningful in vivo role for this and related putative intraovarian regulators.

The ovarian expression of the antigonadotropic insulin-like growth factor binding protein-2 is theca-interstitial cell-selective: evidence for hormonal regulation

To begin the process of identification and charactization of rat ovarian insulin-like growth factor binding proteins, we have undertaken to explore the ovarian expression, cellular localization, and hormonal regulation of the insulin-like growth factor binding protein-2 (IGFBP-2) gene for which an antigonadotropic potential has recently been demonstrated. To this end, a solution hybridization/RNase protection assay was employed wherein total ovarian RNA (20 micrograms) from immature (21-23 days old) female rats was hybridized with a [32P]-labeled IGFBP-2 riboprobe. As in liver, a single protected fragment (550 bases long) corresponding to IGFBP-2 transcripts was identified in whole ovarian material. Cellular localization studies revealed the IGFBP-2 gene to be exclusively expressed in the theca-interstitial rather than the granulosa cell compartment. To confirm the cellular distribution of the IGFBP-2 protein, media conditioned by cultured granulosa or theca-interstitial cells were subjected to immunoprecipitation using two IGFBP-2-directed polyclonal antisera. Expectedly, both antibodies (but not non-immune rabbit serum) readily immunoprecipitated the 28 kDa rat IGFBP-2 species generated by hepatic BRL-3A cells. Similarly, both antibodies effectively immunoprecipitated an IGFBP the size of rat IGFBP-2 elaborated by theca-interstitial cells. In contrast, neither antibody immunoprecipitated the 28-29 kDa IGFBP species elaborated by granulosa cells otherwise readily apparent in conventional Western ligand blots. Hypophysectomy resulted in a 3-fold decrease (P less than 0.05) in the relative (densitometrically-quantified) abundance of ovarian IGFBP-2 transcripts, a diametrically opposed effect (P less than 0.05) being noted at the level of the liver. In contrast, treatment of immature hypophysectomized rats with a diethylstilbestrol-containing subcutaneous silastic implant for a total of 5 days resulted in a concordant 3-fold increase (P less than 0.05) in the relative abundance of IGFBP-2 transcripts in both ovary and liver when compared with untreated hypophysectomized controls. Taken together, these findings document rat ovarian IGFPB-2 gene expression to be theca-interstitial (rather than granulosa) cell-selective, and subject to upregulatory control by pituitary principle(s) and/or by estrogens. Although equally estrogen-dependent, hepatic IGFBP-2 gene expression proved constitutive in nature and subject to (diametrically opposed) inhibitory control by (potentially distinct) pituitary principle(s).

Cytokine-mediated regulation of ovarian function: interleukin-1 inhibits gonadotropin-induced androgen biosynthesis

Resident ovarian macrophages have long been recognized as potential in situ regulators of ovarian function, presumably through local paracrine secretion of regulatory molecules (i.e. cytokines). One such macrophage product, interleukin-1 (IL-1) has recently been shown to exert profound regulatory effects at the level of the ovarian granulosa cell. In this report, we examine the possibility that the adjacent theca-interstitial (androgen-producing) cell may also be a site of IL-1 reception and action. The basal accumulation of androsterone, the major androgenic steroid synthesized by whole ovarian dispersates from immature rats, in the presence of insulin (1 microgram/ml), increased 8- to 9-fold after treatment with human CG (1 ng/ml). Although IL-1 alpha or IL-1 beta (10 ng/ml) by themselves were without effect on basal androsterone accumulation, both cytokines (IL-1 beta greater than IL-1 alpha) inhibited human CG hormonal action (in the presence of insulin) in a dose-dependent manner, the maximal inhibitory effect being 75%. Similar results were obtained when using highly purified theca-interstitial cells derived from the same animal model suggesting that IL-1-attenuated androgen biosynthesis is due, at least in part, to IL-1 acting directly at the level of the theca-interstitial cells. The IL-1 effect proved relatively specific since all other known interleukins (IL-1, IL-3, IL-4, IL-5, and IL-6) were without effect. Moreover, IL-1 beta action was effectively immunoneutralized when concurrently applied with anti-IL-1 beta (but not nonimmune) sera. Significantly, the antigonadotropic action of IL-1 could not be accounted for by a decrease in the viable cell mass. Tracer studies with radiolabeled steroid substrates suggested that IL-1-attenuated ovarian androsterone accumulation is due, if only in part, to inhibition of transformations catalyzed by (theca-interstitial) 17 alpha-hydroxylase/17:20 lyase, stimulation of theca-interstitial (or granulosa 20 alpha-hydroxysteroid dehydrogenase-mediated conversions, or both. Taken together, these findings indicate that relatively low concentrations of IL-1, possibly originating from somatic ovarian cells or resident ovarian macrophages, are capable of exerting an inhibitory effect upon gonadotropin-supported androgen production. As such, these and previous observations suggest that intraovarian IL-1 may play a dual regulatory role in the developing ovarian follicle by targeting both the granulosa and theca-interstitial cells as its sites of action.

The measurement of osteoporosis in clinical practice

It has been reported that metacarpal morphometry does not correlate with iliac crest histomorphometry in patients with hip fractures. Such disagreement led us to study the correlation between both types of measurements on 35 patients who had suffered hip fracture. We observed a significant correlation between metacarpal morphometry and iliac crest cortical width (p less than 0.001), and to a lesser degree with the trabecular bone volume (p less than 0.01). The same was also true if we assessed separately the patients with cervical or trochanteric hip fractures.

Insulin-like growth factor I as an intraovarian regulator: basic and clinical implications

Although much remains to be learned with respect to the possible relevance of IGF-I to ovarian physiology, it may be possible at this time to tentatively formulate possible functions of IGF-I in this connection: 1. Amplification of gonadotropin hormonal action--a key requirement given the exponential nature of follicular development. 2. Integration of follicular development--an essential facet concerned with the coordination of granulosa-theca cooperation. 3. Selection of dominant follicle(s)--a speculative proposition assuming timely and selective activation of the IGF-I system in "chosen" follicles. Aside from its possible role(s) in the course of established follicular cycles, IGF-I (and/or IGF-II) may also participate in the very formation of the follicular apparatus during the late fetal/early neonatal period. Although the ovary is gonadotropin-independent at that time, we previously showed that IGF-I may well interact with VIPergic input now implicated in the morphodifferentiation of the follicular apparatus. Similarly, IGF-I may be concerned with the promotion of juvenile and early pubertal follicular gonadotropin (FSH) levels; ovarian IGF-I may have a bearing on the puberty-promoting effect of growth hormone. Indeed, an association appears to exist between isolated growth hormone deficiency and delayed puberty in both rodents and human subjects, a process reversed by systemic growth hormone replacement therapy. Given that ovarian IGF-I and its receptor may be growth hormone-dependent, it is tempting to speculate that the ability of growth hormone to accelerate pubertal maturation may be due, at least in part, to the promotion of ovarian IGF-I production and reception with the consequent local potentiation of gonadotropin action.

In vivo regulation of granulosa cell type I insulin-like growth factor receptors: evidence for an inhibitory role for the putative endogenous ligand(s) of the ovarian gonadotropin-releasing hormone receptor

The putative endogenous occupant(s) of the ovarian GnRH receptor may play a role as an intraovarian regulator. In this communication we explore the possibility that in vivo activation of the ovarian GnRH receptor may prove heteroregulatory to the murine granulosa type I insulin-like growth factor (IGF) receptor complement. To eliminate potentially confounding pituitary involvement, exclusive use was made of hypophysectomized rats, thereby allowing study of the direct ovarian effect(s) of GnRH receptor ligands. Treatment of immature hypophysectomized rats, thereby allowing study of the direct ovarian effect(s) of GnRH receptor ligands. Treatment of immature hypophysectomized diethylstilbestrol-primed rats with a GnRH agonist (25 micrograms/rat, twice daily) for 2.5 days resulted in a 2.1-fold decrease in FSH (10 micrograms/rat, twice daily)-inducible (but not basal) specific [125I]IGF-I binding to isolated granulosa cells. Scatchard analysis of the binding data revealed this effect to be due in large measure to decreased binding capacity (46% inhibition) rather than affinity (2.5 x 10(-9) M). Although in vivo treatment with a GnRH antagonist (25 micrograms/rat, twice daily) by itself proved without significant effect on the specific binding of IGF-I to isolated granulosa cells, the concurrent provision of a minimally effective dose of FSH (1 microgram/rat, twice daily) resulted in a 2.8-fold amplification of the FSH effect consequent to enhanced binding capacity (110%), but not affinity (2.2 x 10(-9) M). Significantly, this level of binding proved comparable to that induced by a maximally effective dose of FSH when used by itself. Combined pretreatment with identical doses of both peptide analogs had little or no effect on granulosa cell IGF-I binding, suggesting stereospecificity of action and mutual neutralization by the opposing actions of the GnRH receptor ligands employed. The ability of ligands of the GnRH receptor to alter the granulosa cell type I IGF receptor complement proved functionally significant, as assessed by corresponding alterations in IGF-I hormonal action. Indeed, pretreatment with a GnRH antagonist resulted in a 2.1-fold enhancement of IGF-I (50 ng/ml)-supported proteoglycan biosynthesis, with the agonistic analog producing a diametrically opposite effect. Moreover, the ovarian effects of GnRH receptor ligands were not limited to type I IGF receptor binding; comparable effects were noted on basal and hCG-stimulated accumulation of progesterone by cultured granulosa cells, ovarian weight, ovarian protein content, as well as size and number of antral follicles.(ABSTRACT TRUNCATED AT 400 WORDS)

Reversion of the steroid-induced decrease of serum osteocalcin with sodium fluoride

Osteopenia observed in corticotherapy is due, among other causes, to a decrease in bone formation as can be shown by a steroid-induced osteocalcin decrease. Although various treatments have been proposed there is no agreement as to which one is the best. Two such treatments, sodium fluoride and vitamin D administration increase osteocalcin levels. We treated a group of 12 patients under corticoid therapy (mean dose 16 mg per day) with 50 mg/day p.o. sodium fluoride, and determined osteocalcin levels before and two weeks after sodium fluoride treatment. Similarly, another group of 9 patients with a similar mean steroid dose was treated with 0.5 micrograms/day of 1 alpha (OH)2D3 in order to assess the effect of this vitamin on osteocalcin and to determine which was the best treatment. Both groups were compared with respective control groups. A significant osteocalcin increase was observed in the control groups (p less than 0.001); similar significance was observed in the sodium fluoride group, whereas a lower significance (p less than 0.01) was observed in the vitamin D group. These results suggest that sodium fluoride could be more effective than vitamin D in the treatment of steroid-induced osteopenia.

Ovarian granulosa cell-derived insulin-like growth factor binding proteins: modulatory role of follicle-stimulating hormone

Recent observations disclosed the multiplicity of granulosa cell-derived high affinity insulin-like growth factor binding proteins (IGFBPs) and revealed the striking ability of high doses of FSH to suppress their constitutive release under both in vitro and in vivo circumstances. It is the objective of this communication to characterize in greater detail the modulatory effect(s) exerted by FSH on the elaboration of IGFBPs by granulosa cells from immature, estrogen-primed rats. The ability of FSH to regulate the elaboration of granulosa cell-derived IGFBPs proved dose-dependent but biphasic in nature. Specifically, FSH concentrations in the range of 1-3 ng/ml applied for 72 h produced a significant (P less than 0.05) increase in polyethylene glycol-precipitable [125I]IGF-I binding activity corresponding to all IGFBP species detectable by ligand blotting. In contrast, treatment with higher concentrations (greater than or equal to 10 ng/ml) of FSH resulted in progressive dose-dependent inhibition of the constitutive release of IGF-I binding activity (80% inhibition at the 100 ng/ml dose level) and the virtual elimination of all detectable IGFBP species. Time-course studies disclosed a significant (P less than 0.05) initial (apparent at the 24-h time point) stimulatory effect of a high dose of FSH (100 ng/ml) corresponding mostly (but not solely) to the single minor (23K) IGFBP band. In contrast, more prolonged exposure to FSH (greater than or equal to 48 h) produced progressive time-dependent decrements in IGF-I binding activity, an effect associated with a decrease in the relative representation of the major band doublet (28-29K), the 23K species being all but eliminated under these experimental circumstances. Hypophysectomy produced significant (P less than 0.05) inhibition of the subsequent in vitro release of granulosa cell-derived precipitable IGF-I binding activity strongly suggesting that (presumptively stimulatory) pituitary principles other than FSH are likely involved in the regulation of granulosa cell IGFBP release and that the trophic influence of these putative agents appears to outweight the potential disinhibition of FSH hormonal action. Taken together, these findings indicate that the pituitary regulation of granulosa cell-derived IGFBPs is complex and is not FSH-exclusive. Our findings further indicate that the ability of FSH to regulate granulosa cell-derived IGFBPs is dose- and time-dependent but biphasic in nature, an effect characterized by an early low-dose stimulatory effect and a late high-dose inhibitory effect.(ABSTRACT TRUNCATED AT 400 WORDS)

Ovarian granulosa cell-derived insulin-like growth factor (IGF) binding proteins: release of low molecular weight, high-affinity IGF-selective species

The ovarian granulosa cell has previously been shown to be a site of insulin-like growth factor (IGF) I production, reception, and action. It is the objective of this study to characterize in greater detail the soluble IGF binding activity released by this cell type. To this end, use was made of granulosa cells from immature diethylstilbestrol-treated rats. Serum-free media conditioned for 72 h by cultured untreated cells acquired polyethylene glycol (PEG)-precipitable [125I]IGF-I binding activity. The latter proved cell density-dependent, displaying a minimal inoculum requirement of less than or equal to 3 x 10(5) cells/culture. The daily elaboration of IGF-I binding activity appeared constant throughout the 72 h experimental period, the overall time-dependent accumulation of binding activity (over the same time period) proving virtually additive. Scatchard analysis of detailed competition studies with IGF-I suggests that the latter ligand binds to granulosa cell-derived IGF binding protein(s) (IGFBPs) with an apparent affinity of 3 x 10(-10) M. Qualitatively similar results were obtained when using [125I]IGF-II suggesting that the IGFBPs in question are not IGF-I-selective. In fact, specificity studies using either [125I]IGF-I or [125I]IGF-II revealed a rank order of competitive potencies compatible with that observed in other tissues so studied (IGF-II greater than IGF-I much greater than insulin). The proteinacious nature of the acid-stable IGF binding activity under study was indicated by its sensitivity to relatively low concentrations of cycloheximide, its apparent deactivation following repeated cycles of freezing and thawing, and its virtual elimination when subjected to boiling or trypsin treatment. Cycloheximide-induced blockade of protein biosynthesis also revealed that the IGF binding activity is subject to measurable turnover thereby suggesting that its accumulation represents the balance struck between synthetic and degradative processes. Western ligand blotting of sodium dodecyl sulfate-polyacrylamide gel electrophoresis-fractionated media revealed a non-glycosylated major band doublet of 28-29 kDa. A single minor IGFBP species represented by a 23 kDa band was also appreciated in some but not all experiments. Taken together, these findings document the ability of ovarian granulosa cells to secrete a heterogenous mix of low molecular weight, high-affinity IGF-selective binding species. As such, these observations are in keeping with the concept of a complete intraovarian IGF system replete with ligands, receptors, and soluble binding activity.

Transforming growth factor-beta 1 inhibits ovarian androgen production: gene expression, cellular localization, mechanisms(s), and site(s) of action

It is the aim of this study to establish ovarian transforming growth factor-beta 1 (TGF beta 1) gene expression, to reevaluate its cellular localization, and to explore potential interactions of this regulatory peptide on ovarian androgen biosynthesis. Northern analysis of whole ovarian polyadenylated RNA revealed a single 2.5-kilobase transcript corresponding to the TGF beta 1 precursor. Immunohistochemical staining localized the protein to the thecal-interstitial (interfollicular) compartment. To explore potential autocrine effects of TGF beta 1, use was made of whole ovarian dispersates from immature rats the differentiation of which was monitored by the acquisition of androgen biosynthetic capacity. The accumulation of androsterone, the major androgenic steroid detectable in this culture system, increased 5.4-fold over baseline in response to treatment with hCG (1 ng/ml). This effect was further optimized (2- to 4-fold) by supplementation with insulin (1 microgram/ml) and insulin-like growth factor-I (50 ng/ml). In the absence of these optimizing supplements, TGF beta 1 (10 ng/ml) was without effect on basal androsterone accumulation, producing distinct, albeit relatively limited (25%), inhibition of hCG hormonal action. In contrast, supplement-mediated optimization of ovarian androgen biosynthesis revealed TGF beta 1 to be a highly potent inhibitor (greater than 80%) of hCG hormonal action. This reversible TGF beta 1 action proved time and dose dependent, with a minimal time requirement of 72 h and a median inhibitory dose of 2.6 ng/ml. TGF beta 1 action was not due to diminution in the viable cell mass or altered cAMP generation and, therefore, most likely involved a site(s) of action distal to or independent of cAMP generation. Cellular radiolabeling studies of TGF beta 1-treated ovarian cells disclosed the accumulation of steroid intermediates proximal to the 17 alpha-hydroxylation step, suggesting TGF beta 1-mediated blockade at the level of the steroidogenic enzyme 17 alpha-hydroxylase/17-20-lyase. Taken together, these observations are in keeping with the view that TGF beta 1, possibly of thecal-interstitial origin, may not only play a positive paracrine role at the level of the adjacent granulosa cell (as previously reported), but may also constitute one of several autocrine signals concerned with the regulation of ovarian androgen economy. As such, these findings reaffirm the polyfunctional nature of TGF beta 1 action, as manifested by its diametrically opposed effects in different ovarian compartments.

Rat ovarian insulin-like growth factor II gene expression is theca-interstitial cell-exclusive: hormonal regulation and receptor distribution

While the potential role of insulin-like growth factor (IGF)-I in ovarian physiology has been extensively studied, relatively limited attention has been paid to IGF-II the very presence of which in the mature rat ovary has been questioned. In the present study, we have reevaluated rat ovarian IGF-II gene expression, its cellular localization, hormonal regulation, and site(s) of receptor interaction. IGF-II mRNA was detected in whole ovaries from immature as well as mature intact rats. Cellular localization studies revealed IGF-II transcripts in theca-interstitial but not granulosa cells (a site of IGF-I gene expression). In contrast, no cellular selectivity was noted for Type I and Type II IGF receptor gene expression, both of which were clearly detectable in both granulosa and theca-interstitial cells. In vivo treatment of immature hypophysectomized rats with diethylstilbestrol reduced ovarian IGF-II mRNA levels while increasing IGF-I mRNA levels. Taken together, these and previous observations reveal fundamental differences in the cellular localization and hormonal regulation of ovarian IGF gene expression in that IGF-II gene expression (unlike IGF-I) is theca-interstitial (rather than granulosa) cell-specific, and is subject to down (as opposed to up) regulation in response to estrogenic stimulation. In contrast, Type I and Type II IGF receptors exist on both somatic cell types of the rat ovary. These observations are consistent with the view that IGF-II of theca-interstitial cell origin may not only play an autocrine role but may also serve as one of several signals through which this androgen-producing cell may communicate in a paracrine fashion with the adjacent granulosa cell compartment.

Basic fibroblast growth factor inhibits gonadotropin-supported ovarian androgen biosynthesis: mechanism(s) and site(s) of action

Current evidence favors the hypothesis that granulosa cell-derived basic fibroblast growth factor (bFGF) may be the centerpiece of an intraovarian autocrine loop. In this report we examine the possibility that bFGF may also be involved in paracrine interactions at the level of the ovarian theca-interstitial cell. To this end, whole ovarian dispersates obtained from immature rats were cultured for 96 h under serum-free conditions. The accumulation of androsterone, the major androgenic steroid detected, increased 3- to 5-fold over baseline in response to treatment with hCG (1 ng/ml), an effect further optimized (2- to 4-fold) by supplementation with insulin-like growth factor-I (10 ng/ml), insulin (1 microgram/ml), terbutaline (10(-6) M), or high density lipoprotein (100 micrograms/ml). In the absence of these optimizing supplements, bFGF was without effect on basal androsterone accumulation, but produced a relatively modest (20%) inhibition of hCG hormonal action. In contrast, bFGF proved a highly potent inhibitor (80%) of hCG-stimulated androgen biosynthesis in supplement-enriched cultures. This reversible bFGF action proved to be time and dose dependent, with a minimal time requirement of 48 h and a median inhibitory dose of 2 ng/ml. Unaccounted for by altered (hCG-stimulated) cAMP generation or a diminution in the viable cell mass, the antigonadotropic effect of bFGF may by inference be assumed to involve a site(s) of action distal to or independent of cAMP generation. In this connection, cellular radiolabeling with [3H] pregnanolone (3 alpha-hydroxy-5 alpha-pregnane-20-one) revealed bFGF to be a potent inhibitor of the steroidogenic enzyme 17 alpha-hydroxylase/17-20-lyase. As such, these findings are in keeping with the possibility that locally derived bFGF may exert a dual inhibitory action on (mature) ovarian estrogen production by reducing androgen substrate provision as well as by exercising its now established ability to attenuate granulosa cell aromatase activity.

Effect of calcium pidolate on biochemical and hormonal parameters in involutional osteoporosis

The purpose of this study was to determine the value of calcium pidolate in the treatment of involutional osteoporosis. This compound has been reported to be better absorbed than other calcium salts, to lower the levels of parathyroid hormone (PTH) and to raise those of growth hormone (GH). We accordingly treated one group of 10 women suffering from involutional osteoporosis with the equivalent of 1 g elemental calcium and administered a placebo to a second group of 10 osteoporotic women whose mean age and body surface area were comparable. Basal sequential multiple analysis (SMA-12) was performed in all subjects to determine calcium, phosphorus, alkaline phosphatase (ALP) and total protein levels, the same blood samples being used for the evaluation of mean PTH, GH and osteocalcin (BGP). Urinary 24-h calcium excretion was determined and the calcium/creatinine (Ca/Cr) and hydroxyproline/Cr (HP/Cr) ratios were measured in 12-h fasting urine samples, the results being corrected for glomerular filtrate. The same parameters were measured again following a month of uninterrupted treatment. After 30 days, we observed no differences in either group as regards calcaemia, phosphataemia, ALP, total proteins, PTH, GH, BGP or 24-hour calciuria. The only noteworthy changes seen were significant decreases (P less than 0.001) in the Ca/Cr and HP/Cr ratios in the group treated with calcium pidolate. These results show that calcium pidolate at the dose administered inhibits bone resorption but does not affect the levels of PTH, GH, BGP or ALP in the medium term. Our findings indicate that it has no influence on bone formation.

Osteopenia in rheumatoid arthritis: a biochemical, hormonal and histomorphometric study

To determine whether the osteopenia of rheumatoid arthritis (RA) is due to reduction of trabecular bone mass (TBV) and/or cortical width (CW), we evaluated these parameters by bone histomorphometry; we also measured the calciotropic hormones parathormone(PTH) and calcitonin (CT), vitamin D [25(OH)D] and the biological markers of bone remodeling in a group of patients with RA. Study subjects were divided into Group C - premenopausal patients, and Group A - menopausal patients and men of the same ages. These groups were compared to two age-matched control groups, B and D. In both A vs. B and C vs. D, TBV and CW were significantly lower in patients. There were no differences in PTH or CT, but 25(OH)D was significantly reduced, and BGP, OHP/Cr and AP were raised in patients. Patients also exhibited TBV loss in more than 55% and CW loss in more than 98%. These changes suggest that the decline in bone mass, mainly cortical, but also trabecular, is due to increased bone turnover and enhanced resorption and seem to reflect intrinsic alterations of RA.

Treatment of multiple myeloma with nasal spray calcitonin: a histomorphometric and biochemical study

To evaluate the effect of calcitonin on the bone lesions of multiple myeloma, we studied 11 patients treated for 3 months with salmon calcitonin in nasal spray (200 IU) and 500 mg of elemental calcium/day. Pre- and post-treatment biochemical and histomorphometric parameters were compared to those of 12 patients treated for the same time with 500 mg elemental calcium alone. Both groups received the same hematological treatment. In the group treated with calcitonin there was a significant increase (P less than 0.01) in trabecular bone volume, cortical thickness, osteoid volume and osteoid seam thickness index and the osteoclast resorption surface fell significantly (P less than 0.01). There was also a decline (P less than 0.001) in corrected serum calcium and OHP/Cr, which accounts for the diminished bone resorption. The group not treated with calcitonin showed only significant changes in OHP/Cr which increase (P less than 0.05). Calcitonin was perfectly tolerated by all patients and our results show it to be useful in the treatment of bone lesions of multiple myeloma.

Follicle-stimulating hormone inhibits the constitutive release of insulin-like growth factor binding proteins by cultured rat ovarian granulosa cells

The ovarian granulosa cell has previously been shown to be a site of insulin-like growth factor (IGF)-I production, reception, and action. It is the purpose of this communication to explore the possibility that this cell type is also capable of hormonally-regulatable elaboration of IGF binding proteins (BPs). To this end, granulosa cells from immature, diethylstilbestrol-primed rats were cultured for up to 72 h under serum-free conditions in the absence or presence of FSH (100 ng/ml). Media conditioned by untreated granulosa cells revealed constitutively released polyethylene glycol (PEG)-precipitable [125I] IGF-I binding activity the daily elaboration of which proved constant throughout the 72 h experimental period. However, treatment of granulosa cells, with FSH resulted in dramatic inhibition of the accumulation of IGF-I binding activity (89% at the 100 ng/ml dose level). Systemic provision of FSH (10 micrograms/rat/day for 2 days) revealed that this gonadotropic action is not strictly an in vitro phenomenon but that it can be fully reproduced under in vivo circumstances. Western ligand blotting of SDS-PAGE-fractionated media conditioned by untreated granulosa cells revealed three IGF-BP species comprising a major band doublet (28-29 kDa) as well as a single minor band (23 kDa). Treatment with FSH virtually eliminated the 23 kDa species and substantially reduced the relative representation of the 28 and 29 kDa IGF-BP species (82 and 74% inhibition, respectively). Taken together, these observations disclose the multiplicity of granulosa cell-derived IGF-BPs and reveal the striking ability of FSH to suppress their constitutive release under both in vitro and in vivo circumstances. This FSH action is all the more noteworthy in light of the generally stimulatory effect exerted by FSH at the level of the granulosa cell. Inasmuch as FSH may be concerned with the promotion of granulosa cell development, its ability to attenuate the release of (presumptively inhibitory) IGF-BPs may enhance the access of endogenously-produced IGF-1 to its cognate cell surface receptors and hence its cellular hormonal action.

Hyperparathyroidism in metastases of prostatic carcinoma: a biochemical, hormonal and histomorphometric study

Secondary hyperparathyroidism can develop as a result of bone metastases from prostatic cancer, but this has not been studied from the multiple aspects of biochemistry, hormonal status and histomorphometry. In 20 patients with stage-D prostatic cancer, a transiliac bone biopsy was performed for histomorphometric study. In all of them, molecular parathormone (PTH-M) and osteocalcin were determined by radioimmunoassay together with other parameters considered to be biological markers of bone remodelling. Of these 20 patients, only 2 (10%) had elevated PTH-M (240 +/- 20.6 pmol/l), differing significantly from the other 18 (58.6 +/- 11.7 pmol/l) and from controls (60.4 +/- 7.2 pmol/l). In the high PTH-M patients, corrected calcium was low (7.8 +/- 0.4 mg/dl) as compared to normal PTH-M patients (9.2 +/- 0.5 mg/dl, p less than 0.001), and this was also the case for serum phosphorus (2.2 +/- 0.6 vs. 3.2 +/- 0.3 and 3.4 +/- 0.4 mg/dl, respectively p less than 0.001). Alkaline phosphatase was raised in the patient groups as compared to controls (p less than 0.001) and was higher in the high PTH-M group (362 +/- 58 vs. 224 +/- 62 U/l, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Bone radiogrametry: caliper versus magnifying glass

Radiogrametry was done on 100 hands by two observers using two methods: (1) caliper and (2) magnifying glass measurement. At the mid-point of the second metacarpal, the total width (D) and medullary width (d) were measured and cortical thickness (C) was calculated from the difference (D-d). Statistical analysis disclosed that the intra-observer CV is smaller for both observers using the magnifying glass than with the caliper (1.9 and 2.1% vs. 2.8 and 4.3%, respectively). The inter-observer CV is also less with the magnifying glass (4.2 and 5.7% vs. 6.2 and 6.9%, respectively). Although measurements made with each method correlate significantly, the values (mean +/- SD) obtained in isolated measurements using each method differ significantly, with C for both observers, as well as the intra-observer coefficient of variation (CV), being smaller. These results, which demonstrated different bone mass values as quantitated using a caliper or magnifying glass, indicate the greater reliability and precision of the latter method.

Suggestion of a deficient osteoblastic function in diabetes mellitus: the possible cause of osteopenia in diabetics

The mechanism underlying diabetic osteopenia is still unclear and may involve osteoblastic activity and/or the deficit of insulin's anabolic action. Bone gla protein (BGP) is synthesized by the osteoblast and its synthesis increases with 1,25(OH)2D3 and fluoride. Because 1,25(OH)2D3 also stimulates insulin secretion, sodium fluoride administration can be used to investigate deficient osteoblastic activity in diabetics, as reflected by BGP levels. BGP was determined before and after administering sodium fluoride at a dosage of 50 mg/day/15 days to three groups: 14 patients with insulin-dependent diabetes, 16 diabetics on oral antidiabetic treatment, and 25 controls, all of similar age, sex, and characteristics. Basal BGP values (mean +/- SD) were low in diabetics on insulin treatment (4.3 +/- 1.1 ng/ml) and in diabetics on oral antidiabetics (5.8 +/- 1.2 ng/ml) as compared with controls (6.5 +/- 0.7 ng/ml) (P less than 0.001 and less than 0.05, respectively). After giving fluoride, BGP values did not change in the two diabetic groups but did vary in controls (8.1 +/- 0.6 ng/ml, P less than 0.001). These results suggest that deficient osteoblast function could be responsible for osteopenia in diabetics.

Rat ovarian insulin-like growth factor I (IGF-I) gene expression is granulosa cell-selective: 5'-untranslated mRNA variant representation and hormonal regulation

We, and others, have recently reported that the ovary is a site of insulin-like growth factor (IGF)I gene expression. It was the objective of the present studies to assess the relative ovarian abundance of IGF-I transcripts with alternative 5'-untranslated (UT) regions, their cellular localization, and hormonal regulation. To this end, a solution hybridization/RNase protection assay was employed wherein total rat ovarian RNA was hybridized with a 404-base 32P-labelled rat IGF-I riboprobe corresponding to the Class A 5'UT variant. As in liver, three protected bands [322 (Class A), 297 (Class B), and 242 (Class C) bases long] were noted, in keeping with established alternative 5' UT transcripts. The ovarian (as the hepatic) Class C variant proved the most abundant. The ovarian Class B variant was barely detectable. Cellular localization studies revealed these ovarian IGF-I transcripts to be primarily, if not exclusively, of granulosa but not theca-interstitial cell origin. Treatment of immature (21-23 days old) hypophysectomized rats with a diethylstilbestrol (DES)-containing subcutaneous silastic implant for a total of 5 days resulted in a 2-fold increase in the (densitometrically quantified) abundance of ovarian IGF-I transcripts, a diametrically-opposed effect (2.6-fold decrease) being noted at the level of the liver. Whereas treatment of hypophysectomized rats with oGH by itself (150 micrograms, qd, sc x5 days) resulted in a 5-fold increase in hepatic IGF-I gene expression, a limited, albeit distinct inhibitory effect was observed on the steady-state levels of ovarian IGF-I mRNA. In contrast, combined treatment with oGH and DES yielded a 3-fold increase in the abundance of ovarian IGF-I transcripts, there being no net alteration in hepatic IGF-I gene expression. Taken together, these findings reveal ovarian expression of the 3 known 5'-UT IGF-I mRNA variants, document the granulosa cell as the main somatic ovarian cell of IGF-I mRNA generation, and indicate that hepatic and ovarian IGF-I gene expression are differentially regulated in diametrically opposed directions.

Ovarian transforming growth factor-beta (TGF beta): cellular site(s), and mechanism(s) of action

It is the objective of the experiments reported herein to examine the possible relevance of transforming growth factor-beta (TGF beta) to theca-interstitial cell function, and to further characterize the established interaction of TGF beta with the granulosa cell. In examining the interaction of TGF beta (10 ng/ml) with murine theca-interstitial cells, no significant effect was observed on either basal or human chorionic gonadotropin (hCG)-stimulated androsterone accumulation. In contrast, given murine granulosa cells, TGF beta (10 ng/ml) produced dose- and time-dependent augmentation of follicle-stimulating hormone (FSH)-supported aromatase activity with a minimal and median effective doses of 20 +/- 3 and 123 +/- 24 pg/ml, respectively and a minimal time requirement of less than or equal to 48 h. The ability of TGF beta to augment FSH hormonal action could not be accounted for by alteration(s) of specific FSH binding (13965 +/- 298 and 12614 +/- 694 cpm/4 X 10(5) cells for FSH and FSH + TGF beta). However, TGF beta proved capable of exerting a direct upregulatory effect on stimulatable adenylate cyclase activity, further enhancement occurring at site(s) distal to cAMP generation (dibutyryl cyclic AMP (Bt2cAMP) = 1.4 +/- 0.2 ng/culture; Bt2cAMP + TGF beta = 4.1 +/- 0.6 ng/culture). Taken together, our findings are in keeping with the notion that TGF beta, possibly of intraovarian origin, comprises the central signal of autocrine or paracrine loop(s) capable of amplifying gonadotropin action at the level of the granulosa, but not theca-interstitial cell.

Insulin as a regulator of androgen biosynthesis by cultured rat ovarian cells: cellular mechanism(s) underlying physiological and pharmacological hormonal actions

It is the objective of the in vitro studies reported herein to further evaluate the role of insulin in the regulation of ovarian androgen biosynthesis, to assess its dose requirements, and to elucidate the cellular mechanism(s) underlying its high dose action. To this end, use was made of recently developed primary culture systems of ovarian androgen-producing cells, the differentiation of which is subject to regulation by gonadotropic and insulinotropic signaling. Treatment of collagenase-processed whole ovarian dispersates or highly enriched (greater than 90%) thecal-interstitial cells from immature rats with insulin (1 microgram/ml) or hCG (1 ng/ml), resulted in 1.5- and 2.6-fold increments in the accumulation of androsterone (3 alpha-hydroxy-5 alpha-androstan-17-one), the main androgenic steroid identified in culture medium by HPLC. However, combined treatment with both agents unmasked a synergistic interaction resulting in 5.7-fold amplification of hCG action, the increase in androsterone accumulation representing enhanced biosynthesis rather than diminished degradation. Unaccounted for by cellular growth and independent of the cellular density of plating (1 X 10(4)-1 X 10(6) viable cells/culture) or the hCG dose (0.1-10 ng/ml) employed, the insulin effect proved time and dose dependent with a minimal time requirement of 72 h. [125I-TyrA14]Iodoinsulin binding to untreated highly enriched thecal-interstitial cells proved highly specific, saturable, and reversible, displaying a single class (Hill coefficient = 0.93 +/- 0.07) of high affinity (Kd = 1.7 X 10(-10) M), low capacity (4746 +/- 283 sites/cell) binding sites. Treatment with physiological concentrations (10 ng/ml) of insulin produced limited, albeit measureable, down-regulation of the insulin receptor. In contrast, provision of relatively high concentrations (1 microgram/ml) of insulin resulted (despite marked adsorption/degradation) in substantial (greater than 60%) down-regulation of the insulin receptor, but not the type I insulin-like growth factor receptor, the ligand of which has also been shown to amplify hCG-supported androgen biosynthesis. These findings suggest that the thecal-interstitial cell is a site of insulin reception and action, that physiological concentrations of insulin are capable of participating in the regulation of ovarian androgen biosynthesis, and that this effect is probably mediated via high affinity insulin receptors.(ABSTRACT TRUNCATED AT 400 WORDS)