Inhibin and ovarian cancer

Previous observations from our laboratory have demonstrated that the levels of immunoreactive inhibin (ir-inh) are elevated in almost all patients with granulosa cell tumours and in the majority of postmenopausal women with mucinous ovarian cancers. The present manuscript confirms these findings in a larger group of postmenopausal women. Immunohistochemistry for the inhibin alpha, betaA and betaB subunits shows predominantly epithelial staining in granulosa cell tumours and in the majority of mucinous cancers. Serous cystadenocarcinomas also frequently show positive staining. Studies seeking to identify G alpha(i-2) or FSH receptor mutations have provided negative results in contrast to other reports. Further studies of the roles of the inhibin-related family of peptides in ovarian cancer diagnosis and monitoring are clearly indicated.

Serum inhibins A and B fall differentially as FSH rises in perimenopausal women

BACKGROUND

Serum FSH levels rise with increasing age in normal women, particularly as they enter the menopausal transition and progress to the postmenopausal state. The contributions of decreasing levels of inhibin-A (INH-A) and inhibin-B (INH-B) to this rise are presently unclear, as there are no reports of dimeric INH levels in relation to menopausal status. The present study was undertaken in order to provide preliminary data on relationships amongst the dimeric inhibins, oestradiol (E2) and FSH in normal subjects of defined menopausal status.

METHODS

Single serum samples were obtained between cycle days 3 and 8 in regularly cycling women, or at random in those with irregular cycles or amenorrhoea, in 110 women, aged 48-59 years, in the third year of a prospective longitudinal study of the menopausal transition, 'The Melbourne Women's Mid-Life Health Project'. Samples were assayed for FSH, E2, INH-A, INH-B and immunoreactive inhibin (IR-INH) and results were analysed following logarithmic transformation. Undetectable values were assigned the limit of sensitivity of the respective assays. The relationships between hormones were evaluated as a function of menopausal stage. The latter was assigned as Stage 1, premenopausal (no reported change in menstrual cycle pattern), Stage 2, early peri-menopausal (reported change in menstrual cycle frequency in the preceding year with a bleed in the preceding 3 months), Stage 3, late peri-menopausal (no menses in the preceding 3-11 months) and Stage 4, postmenopausal (no menses in the preceding 12 months).

RESULTS

The hormone concentrations in premenopausal subjects (geometric means, FSH 13.5 IU/l, E2 306 pmol/l, IR-INH 217 U/l, INH-A 96 ng/l, and INH-B 48 ng/l) were used as reference points for the other stages of menopausal status. Early peri-menopausal subjects had significantly lower levels of IR-INH (147 U/l) and INH-B (13.5 ng/l) in the presence of a small, statistically nonsignificant rise in FSH (to 21.4 U/l) and no significant change in E2 or INH-A. In late peri-menopausal subjects, IR-INH fell to 76 U/l, INH-A fell to 4.2 ng/l, whilst INH-B was not significantly different at 14 ng/l. FSH had risen significantly to 72.21 U/l. Oestradiol also fell significantly to 89 pmol/l. In the postmenopausal subjects there were no further significant changes in the peptide hormones or FSH, but E2 fell further to 41 pmol/l. There was a significant (P < 0.05) inverse correlation between FSH and E2 (R = -0.78), FSH and IR-INH (R = -0.66), FSH and INH-A (R = -0.53), FSH and INH-B (R = -0.29) while IR-INH and either INH-A or INH-B were positively correlated (R = +0.57 and +0.35, respectively). The data are consistent with negative feedback roles for both dimeric inhibins and E2 as contributors to the regulation of FSH secretion as menopausal status changes.

CONCLUSIONS

The major significant endocrine event in women in the early peri-menopausal phase of the menopausal transition is a substantial fall in the circulating levels of inhibin-B with no significant change in inhibin-A or oestradiol. Progression to late peri-menopausal status is accompanied by a marked fall in inhibin-A and oestradiol and a rise in FSH without further change in inhibin-B. Inhibin-B, a marker of follicle number, is a significant factor in the endocrinology of the menopausal transition.

Loss of the expression and localization of inhibin alpha-subunit in high grade prostate cancer

Serum inhibin levels are elevated in postmenopausal women with granulosa and mucinous epithelial tumors of the ovary. In contrast, functional deletion of the inhibin alpha gene in male and female mice results in the development of primary gonadal granulosa/Sertoli cell tumors. The aim of this study was to determine whether inhibin alpha-subunit gene and protein expression are altered in prostate cancer. Messenger ribonucleic acid expression was studied by in situ hybridization, and protein localization was studied by immunohistochemistry. Inhibin alpha-subunit messenger ribonucleic acid expression and protein localization were observed in the epithelium of tissues from men with benign prostatic hyperplasia, in regions of basal cell hyperplasia, and in nonmalignant regions of tissue from men with high grade prostate cancer. In the malignant regions of tissue from men with high grade prostate cancer, the expression of the inhibin alpha-subunit gene was suppressed and was not detectable in poorly differentiated tumor cells. These results demonstrate that in contrast to ovarian granulosa cell tumors, inhibin alpha gene expression is down-regulated in poorly differentiated prostate cancer.

Effect of desialylation of highly purified isoforms of human luteinizing hormone on their bioactivity in vitro, radioreceptor activity and immunoactivity

To establish whether sialic acid content is responsible for an observed 7-8-fold variability in bioactivity in vitro of highly purified human pituitary luteinizing hormone (hLH) isoforms, the bioactivity in vitro, radioreceptor activity and immunoactivity of hLH isoforms were determined before and after enzymatic desialylation. Three immunofluorometric assays with different hLH specificities allowed characterization of 13-24 pituitary hLH isoform preparations of pI 7.03-8.98 in terms of sialic acid content (1-5 sialic acid residues per LH molecule), bioactivity in vitro (4030-30,000 I.U. mg[-1]), radioreceptor activity (6420-25,400 I.U. mg[-1]) and hLH immunoactivity (2900-4400 to 18,300-27,300 I.U. mg[-1]). Significant positive correlations between sialic acid content and either immunoactivity or in vitro bioactivity were observed, whereas radioreceptor activity showed a curvilinear response. Following more than 90% removal of sialic acid, both in vitro bioactivity and radioreceptor activity were increased, although specific activity still differed between isoforms; immunoactivities were unaffected. It is concluded that the presence of the sialic acid residue(s) on hLH isoforms does partially contribute to the in vitro bioactivity and radioreceptor activity of the isoforms, but that hLH immunoactivity is independent of sialic acid content.

Histopathologic study of eyes after iodine I 125 episcleral plaque irradiation for uveal melanoma

OBJECTIVES

To describe the histopathologic findings attributable to irradiation in eyes with uveal malignant melanoma treated with iodine I 125 brachytherapy and to compare these findings with those reviewed in a previous study that compared histopathologic findings in eyes enucleated after proton beam teletherapy with those seen in eyes in a nonirradiated control group.

METHODS

The slides from 22 eyes with uveal melanoma that had undergone enucleation after the administration of 125I brachytherapy were studied. The histopathologic features of the tumor and the retina were graded. Results were compared with findings from a previously reported group of 47 proton beam-treated eyes and its control group.

RESULTS

Patient age, time between irradiation and enucleation, and ciliary body involvement were similar for the 125I brachytherapy-treated group and the proton beam-treated group and its control group. This allows comparison of the histopathologic findings. Comparing the 125I brachytherapy- and proton beam-treated groups, most histopathologic features were similar with nominally statistically significant differences only for cell type, number of mitotic figures, and fibrous metaplasia of the retinal pigment epithelium adjacent to the tumor.

CONCLUSIONS

Irradiation of uveal melanoma induces changes in the tumor and in the surrounding retina. Brachytherapy and charged particle therapy are the 2 principal methods of irradiation. This study demonstrates that similar changes are produced by 125I plaque irradiation and proton beam irradiation.

Analysis of chorionic gonadotrophin secreted by cultured human blastocysts

Embryos produced in an in-vitro fertilization (IVF) programme, but which were unsuitable for transfer to patients because they originated from one (1PN) or three pronuclear (3PN) oocytes or because they originated from two pronuclear (2PN) oocytes but cleaved normally, were maintained in tissue culture. The embryos that progressed to blastocytes were cultured to day 14 of development in order to study their daily output of human chorionic gonadotrophin (HCG). Blastocysts that released large amounts of immunoreactive HCG, which continued to increase daily during the study period, provided the culture supernatants used in the present studies. The heterogeneity of HCG released by blastocyst tissues on days 11 and 14 of development was studied by a chromatofocusing method which separates the isoforms of the gonadotrophin based on differences in their isoelectric points. It was found that the secreted HCG was composed of several molecular forms and that this heterogeneity changed from day 11 to 14 of development. The early blastocyst tissues produced more acidic HCG isoforms than the more advanced embryonic tissues. Differences in the apparent ploidy of the blastocyst tissues studied did not affect significantly the distribution of the HCG isoforms secreted either on day 11 or day 14 of development. These results suggest that the bioactivity of the HCG secreted by blastocytes may change with time and with differentiation of the trophectoderm. In addition, the results suggest that the ploidy of early blastocytes does not influence the nature of the HCG secreted.

Intravitreal invasion of malignant cells from choroidal melanoma after brachytherapy

We report intravitreal invasion by melanoma cells from a choroidal melanoma after brachytherapy. A malignant melanoma of the choroid with collar-button configuration was treated with iodine 125 brachytherapy. Years later, the collar button developed a dark-chocolate color and began shedding pigmented debris into the vitreous. Coalescence of this debris into spheroidal aggregates suggested the presence of malignant cells; the eye was enucleated. Histologic sections demonstrated a choroidal melanoma with intraretinal and intravitreal invasion by melanoma. Clinical evidence of intraretinal invasion by melanoma cells along with pigmented debris within the vitreous cavity, especially when clustered in spheroidal aggregates, suggests the presence of intravitreal invasion by malignant cells. In this case, intravitreal invasion was verified histologically.

Androgen action on the restoration of spermatogenesis in adult rats: effects of human chorionic gonadotrophin, testosterone and flutamide administration on germ cell number

Spermatogonial proliferation is a critical but poorly understood determinant of the spermatogenic process. In rats, exogenous testosterone plus oestradiol (TE) markedly suppresses serum LH and testicular testosterone levels. In the TE-treated rat, spermatogonial number declines to approximately 65% of control levels while round to elongated spermatid maturation is interrupted. The partial restoration of testicular testosterone levels by exogenous testosterone administration restores spermatid maturation but neither testicular weight nor spermatogonial number are normalized. This study aimed to determine the role of testosterone and/or non-androgenic Leydig cell factors in the restoration of spermatogonial number in the testosterone-treated rat. Germ cell numbers were assessed using stereological methods and expressed as germ cell number per testis. Adult Sprague Dawley rats initially received 3 cm testosterone plus 0.4 cm oestradiol Silastic implants for 9 weeks to suppress spermatogenesis, followed by 10 days of either (i) exogenous testosterone using implants (T24 cm) or testosterone esters (5 or 25 mg sc every third day), or (ii) human chorionic gonadotrophin (hCG; 0.5, 1.25, 2.5 or 10 IU/kg sc daily) as an LH substitute to restore Leydig cell function. Following TE treatment, testicular weights and testicular testosterone levels were reduced to 31% and 1.3% of control levels, respectively. In response to exogenous testosterone administration, testicular weight was restored to 52-58% of controls while testicular testosterone levels increased to only 3.5-17.3% of controls despite serum testosterone levels 4.5-24-fold above control. In response to hCG treatment, a graded increase in testicular testosterone levels was achieved (2.6-20.5% of control) and testicular weights increased to 38-56% of control. TE suppression reduced (p < 0.05) type A spermatogonia and type B spermatogonia/preleptotene spermatocyte numbers per testis to 61% and 77% of control, respectively; however, neither subsequent testosterone nor hCG treatments significantly increased either germ cell number. In a second study, hCG (1.25 IU/kg) was administered alone or in combination with the androgen receptor antagonist, flutamide (100 mg/kg sc daily), to withdraw androgenic effects at all stages of spermatogenesis. The TE-induced suppression of type A spermatogonia (59% control) and type B spermatogonia/preleptotene spermatocytes (68% control) was not affected by hCG +/- flutamide. On the other hand, as expected, hCG increased the number of elongated spermatids (p < 0.05). The co-administration of flutamide reduced (p < 0.05) the numbers of all pachytene spermatocyte forms, round and elongated spermatids below those of TE-treated animals. We conclude that neither exogenous testosterone nor hCG is capable of restoring spermatogonial number in the TE-treated rat within 10 days despite the partial or full restoration of testicular testosterone levels. No evidence was found for the involvement of non-androgenic Leydig factors in the control of spermatogonial numbers. The data from flutamide-treated animals demonstrates that residual androgen effects are present in the TE model as, even in the presence of testicular testosterone levels below that needed for spermatid maturation, further inhibition of spermatocyte development and meiosis is apparent.

The biological and immunological characterization of inhibin A and B forms in human follicular fluid and plasma

In a previous study (see Ref.7), the molecular weight distribution of inhibin activity in fractionated human follicular fluid (hFF) and human male and female plasma/serum was determined by in vitro bioassay using ovine pituitary cells in culture and various specific inhibin A and inhibin alpha-subunit-directed immunoassays. It was shown, however, that the ovine in vitro bioassay detected inhibin B poorly. These findings are extended in the present study by the determination of the molecular weight profile of in vitro bioactivity using rat pituitary cells, which detects both inhibin A and B, a specific inhibin B enzyme-linked immunosorbent assay (ELISA), an RIA detecting the alpha N region of the alpha-subunit, an alpha-subunit ELISA (Pro-alpha C) directed to the inhibin forms containing the Pro sequence, and an alpha C subunit immunofluorometric assay that detects all inhibin forms. The profile in hFF of inhibin in vitro bioactivity, using rat pituitary cells in culture, significantly (P < 0.001) correlated with in vitro bioactivity using ovine pituitary cells (r = 0.85), inhibin A immunoactivity (r = 0.70), inhibin B immunoactivity (r = 0.89), and the combination of inhibin A + B immunoactivities (r = 0.93), with peaks of activity identified at 66K, 55K, 36K and 33K, consistent with presumed known mol wt forms of inhibin. Inhibin B profiles in fractionated serum from women stimulated with gonadotropins and male plasma consisted of two forms (66K and 36K), whereas inhibin A in female serum included, in addition, the 55K form. These findings indicated that higher molecular weight forms of inhibin B are present in biological samples, and their distribution differs from that of inhibin A, suggesting a differential processing of the precursor forms in the circulation. Pro-alpha C immunoactivity was identified in serum samples with prominent peaks at 36K and 29K (known Pro-alpha C subunit forms) and not with any high mol wt dimeric forms of inhibin. If this observation applies to a wider range of serum samples, the Pro-alpha C ELISA may provide an appropriate and specific assay for the measurement of free alpha-subunit. To compare immunoactivity levels between assays, the inhibins A, B, and Pro-alpha C standards were calibrated in terms of their alpha C subunit content, as determined by an alpha C subunit immunoassay, with the inhibin B standard containing 60% of the alpha C subunit content compared with either the inhibin A or Pro-alpha C standard. After adjustments of the various standards for this difference in alpha C subunit content, a comparison was undertaken of the combined levels of inhibins A, B, and Pro-alpha C immunoactivity across the hFF and serum chromatograms and compared with levels determined by the alpha-subunit-directed immunoassays. A high correlation (r = 0.59-0.96) was observed, indicating that the alpha-subunit immunoactivity in serum consists largely of a composite of presumed known molecular weight forms of inhibins A, B, and Pro-alpha C. It is concluded that: 1) inhibin in vitro bioactivity in hFF is largely attributed to the presence of 33-36K and 50-66K forms of inhibins A and B; and 2) inhibin alpha-subunit immunoactivity in hFF and serum is a composite of presumed known forms of inhibin A, inhibin B, and the alpha-subunit.

Structural and functional characterisation of hFSH and hLH isoforms

Human follicle-stimulating hormone (hFSH) and luteinizing hormone (hLH) are gonadotropins which are secreted as multiple forms by the pituitary. Evidence supporting the structural and functional heterogeneity of 15 purified hFSH isoforms and 20 purified hLH isoforms from pituitary extracts will be presented. Gonadotropin isoforms were purified by a combination of preparative isoelectric focusing and ion-exchange chromatography. The protein mass of each isoform was determined by amino acid analysis, which also correlated (data for hLH) (r = 0.999, P < 0.001, n = 15) with the UV area under the curve at 280 nm of the isoforms following gel-filtration HPLC. The alpha and beta subunits of FSH and LH were shown to be intact by SDS-PAGE under reducing condition, with no evidence of proteolytic nicking or presence of contaminating proteins. hFSH radioreceptor activity varied over a seven-fold range, and a positive correlation (r = 0.85, P < 0.001, n = 9) was observed between FSH receptor activity and the sialic acid (SA) content (1.5-13.7 mol SA/mol hFSH) of the isoforms, as determined by an HPLC-based microfluorometric assay. FSH in vitro activities varied over a similar range with a high correlation (r = 0.82, n = 15) with receptor activities, suggesting that the initial association of the hormone with the receptor is the key interaction with less differences attributed to subsequent effects in the signaling pathway. A similar result was seen with the hLH isoforms. To explore FSH/LH in vivo, the circulating half-life (LH/FSH) and the in vivo bioactivity (LH) using an acute in vivo assay was investigated. The clearance of hLH and hFSH showed a bi-exponential pattern for all isoform preparations with the proportion of the slower dissociating component (t 1/2 50-60 min) increasing three-fold with increasing sialic acid content of the isoform. The more rapidly cleared component (t 1/2 approx 10 min) is attributed to hepatically cleared gonadotropin, rather than gonadotropin equilibration between body compartments. The in vivo assay procedure for LH was based on the 24 h integrated plasma testosterone levels in rats following administration of graded doses of hLH isoform or standard. A 16-fold range in vivo activities between LH isoforms (n = 14) was observed. A comparison between hLH in vitro and in vivo activities showed a good correlation (r = 0.75) with the slope of the regression line (1.39) not significantly different from unity. These results suggest that in this acute in vivo assay method, the differences in circulating half-lives between hLH isoforms although large is not a key factor in their in vivo activity. However, in chronic in vivo assay systems the differences in clearance rates between isoforms may be important in their subsequent biological response. It is concluded that structural heterogeneity of FSH and LH contributes to functional differences, with a key interaction occurring at the receptor level. The contribution of sialic acid to these activities was also investigated.

In vivo bioactivities and clearance patterns of highly purified human luteinizing hormone isoforms

Previous studies have shown that highly purified isoforms of human pituitary LH exhibited a 20-fold range of in vitro bioactivities. The aim of this study was to determine the corresponding plasma half-lives, metabolic clearance rates (MCR), and in vivo bioactivities of these human (h) LH isoforms. Cannulated adult male rats were administered hLH isoforms as a bolus i.v. injection. For the half-life studies, blood was then serially collected over a 6-h period, and serum was assayed for hLH using a specific immunofluorometric assay. All hLH (n = 19) isoforms exhibited biexponential disappearance profiles with an initial fast half-life (t 1/2) for component A of 12.8 +/- 3.7 min, followed by a slow component B with t 1/2 of 58.9 +/- 4.4 min. The prevalence of component B in relation to component A increased significantly (r = 0.81, P < 0.001) over a 3-fold range when correlated with the sialic acid content of the isoform. Similarly, the MCR showed a significant correlation (r = 0.77, P < 0.001) with sialic acid content. The basis for the two t 1/2 components was then investigated. In the first experiment, rat plasma containing primarily component B was collected 90 min after hLH isoform administration and injected into a second animal. Only component B was observed with no evidence of component A, which indicates that the two t 1/2 components are not the product of the redistribution of the hLH isoform between body compartments. In the second experiment, component B was found to be dependent on sialic acid content, as desialylated hLH isoforms showed a rapid disappearance (t 1/2 = 8.6 +/- 3.1) with the component B proportion decreasing to < 10% of that of the nondesialylated control. This data indicates that sialic acid protects component B from rapid clearance. In addition, the proportion of the two components is dependent on sialic acid content, suggesting that the molecular location of the sialic acid on the carbohydrate moieties of hLH has a critical role in the clearance process. To determine the in vivo bioactivity of the hLH isoforms, an acute in vivo bioassay was developed in male rats. The assay was based on the hLH dose-dependent increase in total testosterone release in the same rat model as used in the plasma disappearance studies. Using the second International Standard (IS) hLH (0.3 IU-2.6 IU/kg) as standard, a linear dose-response of 24-h integrated serum testosterone levels was observed, with an index of precision of 0.11. Using this in vivo assay, a 16-fold range in in vivo bioactivities (3,200 to 51,100 IU/mg) was observed for 14 hLH isoforms. These in vivo bioactivities correlated with sialic acid content (r = 0.78, P < 0.001), MCR (r = 0.56, P < 0.05) and LH in vitro bioactivity (r = 0.75, P < 0.001) as determined using mouse Leydig cells in culture. Desialylation lead to over a 100-fold decrease in in vivo bioactivity of hLH. It is concluded that hLH isoforms are cleared in vivo by a two-component clearance mechanism, the proportion of which varies between isoforms and is dependent on sialic acid content of the isoform. These findings suggest that the molecular location of sialic acid on the hLH isoform is critical in defining the plasma disappearance of component B, whereas the mechanism of elimination of component A may well involve the hepatic GalNAc-sulphate receptor. Using an in vivo bioassay, the 16-fold difference in bioactivity between isoforms is attributed primarily to differences in their in vitro activity at the cellular level with a minor influence (< 2-fold) due to differences in in vivo clearance.

Testosterone withdrawal promotes stage-specific detachment of round spermatids from the rat seminiferous epithelium

Testosterone (T) has been shown to be essential for the completion of spermiogenesis. Our previous studies showed that when intratesticular T was suppressed for 11 wk, the conversion of round spermatids between stages VII and VIII of the spermatogenic cycle was markedly suppressed and that elongated spermatids were undetectable. The fate of the round spermatids that did not proceed through this conversion was unclear. The current study aimed to investigate this T-dependent loss of round spermatids during stages VII and VIII. Adult male Sprague-Dawley rats received 24-cm T implants for 1 wk to suppress LH while maintaining spermatogenesis. The T24 implants were removed and replaced with 3-cm T plus 0.4-cm estradiol (TE treatment) to suppress intratesticular T and spermatogenesis, and animals were killed at 0 and 4 days and 1, 2, 3, 4, and 6 wk later. The number of homogenization-resistant elongated spermatids in the testis was counted, and round spermatid populations in stages VII and VIII were quantified using stereological techniques. The hourly production rates (HPR) were calculated, and a ratio was made between the HPR of round spermatids in stages VII and VIII to assess the efficiency of their conversion through these stages. Testicular T levels were suppressed to 2-4% of control values by TE treatment. After 2 wk of TE treatment, the number of homogenization-resistant elongated spermatids was significantly suppressed, falling to < 0.5% of the control value by 6 wk. The HPR of round spermatids in stages VII and VIII was not affected by up to 2 wk of TE treatment, nor was the conversion between these stages interrupted. After 3 wk of TE treatment, the HPR of round spermatids in stages VII and VIII was significantly suppressed, as was the conversion between these stages, the ratio falling to 27% of the control value by 6 wk. In rats treated with TE, histological examination of the cauda epididymidis showed occasional round spermatids after 3 wk of treatment, and large numbers after 6 wk. We conclude that the failure of round spermatids to complete spermiogenesis following T withdrawal is due to stage-specific detachment of round spermatids between stages VII and VIII.

Hormonal dependency of neural cadherin in the binding of round spermatids to Sertoli cells in vitro

The procession of round spermatids through stages VII and VIII of the rat spermatogenic cycle is critically dependent on testosterone (T). When intratesticular T levels are reduced, round spermatids appear to slough from the seminiferous epithelium, resulting in the disappearance of elongated spermatids. We hypothesized that T-dependent cell adhesion molecules are involved in Sertoli cell-round spermatid interactions. This study examined the hormonal regulation of one candidate cell adhesion molecule, N-cadherin, in vitro and its participation in Sertoli cell-round spermatid adhesion in coculture. Sertoli cells were isolated from 20-day-old Sprague-Dawley rats; treated with FSH and T, alone or in combination; and incubated for 48 h before determination of N-cadherin concentrations in Sertoli cell extracts by RIA. Both FSH and T significantly increased the cellular content of N-cadherin (3.7-fold), whereas FSH or T alone had no effect. Round spermatids were isolated from adult rats, and their adhesion to Sertoli cells was assessed in a 48-h coculture in the presence of FSH, T, or FSH plus T. Adherent round spermatids were quantitated by histological evaluation after staining with the periodic acid-Schiff reaction. A dose-dependent increase in round spermatid density (number of round spermatids bound per 10,000-microns2 Sertoli cell culture surface area) was observed with increasing T doses (7-28 ng/ml) in the presence of FSH (1 microgram/ml), whereas FSH and T alone at these doses produced no effect. T also increased the N-cadherin content of the cocultures in a dose-dependent manner in the presence of FSH. Addition of an N-cadherin antiserum to the Sertoli cell-round spermatid coculture in the presence of FSH and T significantly (P < 0.0001) reduced round spermatid density by 65%. It is concluded that both the production of N-cadherin by Sertoli cells and the binding of round spermatids to Sertoli cells are stimulated in a synergistic manner by T and FSH. Furthermore, the immunoneutralization data suggest the active involvement of N-cadherin in round spermatid-Sertoli cell adhesion in vitro. N-Cadherin may be one of the factors that subserve the androgen-dependent process of round to elongated spermatid maturation.

Plasma follistatin concentrations increase following lipopolysaccharide administration in sheep

1. The effect of inflammation induced by lipopolysaccharide (LPS) injection on plasma follistatin (FS) concentrations was investigated. 2. Plasma FS and tumour necrosis factor-alpha concentrations increase following LPS administration in ewes. 3. The rise in FS is similar, but more sustained, to that previously observed after surgery. 4. These results indicate a possible functional link between FS, inflammation and the acute-phase response.

Inhibition of 5 alpha-reductase activity impairs the testosterone-dependent restoration of spermiogenesis in adult rats

Testosterone (T) is required for spermatogenesis, particularly in the conversion of round spermatids between stages VII and VIII of spermatogenesis. T is generally thought to be the major androgen involved in adult spermatogenesis due to the high local concentration within the testis, whereas its more potent 5alpha-reduced metabolite dihydrotestosterone (DHT) is thought to be the active androgen in peripheral tissues. The current study investigated whether 5alpha-reduction of T to DHT is involved in the restoration of spermiogenesis in vivo in a setting in which testicular T levels were markedly reduced. Adult male rats were given 3-cm T plus 0.4-cm estradiol implants for 9 weeks to suppress serum LH and testicular T levels and thereby inhibit spermatogenesis. Increasing doses of T (3-, 6-, 10-, and 24-cm implants) were then given for 4 days to restore spermatogenesis in the presence or absence of a 5alpha-reductase inhibitor (L685,273). The hourly production rates of round spermatids in stages I-III, IV-VI, VII, and VIII were assessed using stereological techniques, and the conversion of round spermatids between stages VII and VIII was then assessed as an index of androgen action on spermiogenesis. Testicular androgen levels were measured by HPLC and RIA. The 5alpha-reductase inhibitor significantly suppressed (P < 0.05) the hourly production rate of round spermatids at the 3- and 6-cm T doses, but not at the 10- and 24-cm doses. The conversion of round spermatids between stages VII and VIII was suppressed (P < 0.05) by the inhibitor only at the 3- and 6-cm doses. The 5alpha-reductase inhibitor had no effect on testicular T levels, but suppressed (P < 0.05) DHT levels at the 6-, 10-, and 24-cm doses. We conclude that the 5alpha-reduction of T is involved in the restoration of spermiogenesis at the lower administered doses of T and that these data are the first description of a role for 5alpha-reduced androgens in adult spermatogenesis.

Biological activity and metabolic clearance of recombinant human follicle stimulating hormone produced in Sp2/0 myeloma cells

Human follicle stimulating hormone is a pituitary glycoprotein that is essential for the maintenance of ovarian follicle development and testicular spermatogenesis. Like other members of the glycoprotein hormone family, it contains a common a subunit and a hormone specificβ subunit. Each subunit contains two glycosylation sites. The specific structures of the oligosaccharides of human follicle stimulating hormone have been shown to influence both thein vitro andin vivo bioactivity. Since the carbohydrate structure of a protein reflects the glycosylation apparatus of the host cells in which the protein is expressed, we examined the isoform profiles,in vitro bioactivity and metabolic clearance of a preparation of purified recombinant human follicle stimulating hormone derived from a stable, transfected Sp2/0 myeloma cell line, and pituitary human follicle stimulating hormone. Isoelectric focussing and chromatofocussing studies of human follicle stimulating hormone preparations both showed a more basic isoform profile for the recombinant human follicle stimulating hormone compared to that of pituitary human follicle stimulating hormone. The recombinant human follicle stimulating hormone had a significantly higher radioreceptor activity compared to that of pituitary human follicle stimulating hormone, consistent with a greaterin vitro potency. Pharmacokinetic studies in rats indicated a similar terminal half life (124 min) to that of the pituitary human follicle stimulating hormone (119 min). Preliminary carbohydrate analysis showed recombinant human follicle stimulating hormone to contain high mannose and/or hybrid type, in addition to complex type carbohydrate chains, terminating with bothα2,3 andα2,6 linked sialic acids. These results demonstrate that recombinant human follicle stimulating hormone made in the Sp2/0 myeloma cells is sialylated, has a more basic isoform profile, and has a greaterin vitro biological potency compared to those of the pituitary human follicle stimulating hormone.

The long-term outcome of central serous chorioretinopathy

OBJECTIVE

To assess the long-term outcome of central serous chorioretinopathy (CSR) among a group of patients who previously participated in a prospective argon laser photocoagulation study of CSR.

DESIGN

Thirty-eight of 41 surviving patients with CSR participating in an earlier study were invited to participate in a follow-up study that included history taking, ophthalmoscopy, biomicroscopy, and fundus photography.

RESULTS

Thirty-seven (38 eyes) of 38 surviving patients (97%) were available for follow-up between 11 and 15 years after participation in the earlier study. There were no clinically documented or historical recurrences of CSR among the six eyes previously treated by direct laser photocoagulation. There were 13 clinically documented recurrences and four historical recurrences among the 32 eyes not treated with direct laser photocoagulation. The difference in recurrences was statistically significant (P = .02). Pigment changes indistinguishable from age-related macular degeneration frequently occurred in eyes with CSR. The difference in the development of such pigment changes between eyes with CSR (33 of 38) and nonaffected fellow eyes (12 of 35) was significant (P = .001).

CONCLUSIONS

The decreased rate of CSR recurrence after direct laser photocoagulation reported in an earlier study was sustained with follow-up beyond 10 years. Pigmentary changes in the fundus indistinguishable from those associated with age-related macular degeneration developed in eyes affected with CSR, probably as a consequence of the presence of subretinal fluid accompanying the CSR rather than from early age-related macular degeneration.

The testis is not the major source of circulating follistatin in the ram

The aims of this study were to determine the plasma concentrations of follistatin in rams and to assess if the testis contributes to circulating follistatin and if there is uptake or production of follistatin by the head in rams. Catheters were inserted in the carotid artery, jugular vein and spermatic vein of intact rams during the non-breeding season (experiment 1; n = 5) and breeding season (experiment 2; n = 4). In experiment 1, blood samples were collected from 5 rams every 10 min for 4 h, commencing 20-60 min after surgery. After 2 h of sampling 1 microgram gonadotrophin-releasing hormone (GnRH) was injected intravenously. In experiment 2, blood samples were collected from 4 of the rams used in experiment 1 by venipuncture 30 and 15 min before surgery and every 15 min throughout surgery. Commencing 1 h after surgery, matched samples were taken from each of the vessels every 10 min for 4 h (1-4 h after surgery), then every hour for 20 h (4-24 h after surgery) and then every 10 min for 4 h (24-28 h after surgery). In both experiments, follistatin secretion was non-pulsatile and there were no significant differences between the concentrations of follistatin in any of the vessels. There was a significant (P < 0.05) increase in the concentrations of follistatin in each of the vessels throughout the 4 h of 10-min sampling in both experiments. In experiment 2 plasma concentrations of follistatin in the jugular vein were significantly (P < 0.05) lower before surgery than at other stages of the experiment. During the non-breeding season (experiment 1) the concentrations of follistatin in all vessels were about 2-fold higher (P < 0.001) than during the breeding season (experiment 2). Concentrations of follistatin were measured in the testicular tissue of the ram, bull, monkey and rat and were found to be 13.6, 2.1, 2.5, 0.8 ng/g testis respectively. In experiment 3, blood samples were collected every 15 min for 4 h from castrated rams (n = 6) in the absence of treatment with testosterone propionate (TP) and after 7 days of treatment with a physiological dose of TP during the breeding and non-breeding seasons. There was no effect of stage of breeding season or TP on the plasma concentrations of follistatin and these concentrations in the castrated rams were similar to the concentrations in the intact rams in experiment 2. In experiment 4, the function of Leydig cells was stimulated by administration of human chorionic gonadotrophin but this had no effect on plasma concentrations of follistatin. These experiments show that the concentrations of follistatin in the plasma of rams are measurable, that the testis is not the major contributor to circulating follistatin and that there is no significant uptake or production of follistatin by the head in rams. It appears that the contribution of the testis to circulating follistatin may vary with the stage of the breeding season, being greater during the non-breeding season than the breeding season. The gonadotrophins and testosterone do not appear to have a direct effect on the secretion of follistatin in rams. The increase in concentrations of circulating follistatin during surgery and more frequent blood sampling suggest a stress-related effect on the production of follistatin.

The control of ovulation in mothers of dizygotic twins

Dizygotic twinning is familial, suggesting that there may be an inherited abnormality of the control of ovulation that predisposes to double ovulation and, therefore, dizygotic twins. The present study examines 17 mothers of dizygotic twins (MODZT) and 8 control mothers of singletons by daily blood sampling throughout an entire menstrual cycle. Blood samples were assayed for LH, FSH, estradiol, progesterone, and inhibin. The process of follicular development was followed by transvaginal ultrasound. The pituitary LH response to iv GnRH was also assessed. Three of the 16 MODZT double ovulated during the study compared to none of the 8 control mothers (P < 0.05). The number of small follicles (<6 mm) declined significantly in control women at midcycle, but not in MODZT. There was no significant difference in serum FSH, LH, estradiol, or inhibin levels between the 2 groups at any stage of the menstrual cycle. During the follicular phase, serum progesterone levels were significantly higher in MODZT. The response to GnRH stimulation was not different between MODZT and controls. In conclusion, this study demonstrates an increased tendency to double ovulate in MODZT that may be due to a reduced rate of atresia in advanced follicles. Furthermore, the elevated progesterone levels in MODZT during the follicular phase suggest altered intrafollicular steroidogenesis that is independent of gonadotropins.

Measurement of activin in biological fluids by radioimmunoassay, utilizing dissociating agents to remove the interference of follistatin

Activin, a dimer of the beta-subunits of inhibin, is a member of the transforming growth factor beta (TGF-beta) superfamily of growth factors and has a widespread range of actions in a variety of tissues. The investigation of the physiology of activin action has been facilitated in recent years by the availability of immunoassays in addition to bioassays. Follistatin has been shown to bind to activin with a high affinity and therefore interferes in both radioimmunoassays and enzyme-linked immunosorbent assays (ELISAs). In this study we examined the effect of various surfactants and 1.4-dioxane on the measurement of activin in the presence of follistatin by radioimmunoassay. The addition of a combination of sodium deoxycholate. Tween 20 and sodium dodecyl sulphate removed the interference of follistatin in the radioimmunoassay. The measured content of activin in male rat serum, human male serum, human female serum and bovine follicular fluid rose from 3.29 to 4.15, < 0.48 to 2.87, 2.42 to 4.17 and 30.9 to 85.6 ng/ml, respectively, when assayed in the presence of the dissociating reagents. It was unclear whether the altered potencies were due to a dissociation of the follistatin/activin complex rather than the exposure of the epitope on activin recognized by the antiserum. Serum concentrations of activin were lower than those found in testicular cytosols, and after castration no change in serum activin levels was observed, suggesting that the testis does not contribute significantly to circulating activin levels. The use of the dissociating reagents in the radioimmunoassay will enable studies to be carried out that more accurately measure the activin content of various biological fluids, and thus lead to a greater understanding of the physiology of this growth factor.

Characterization of inhibin immunoreactivity in post-menopausal women with ovarian tumours

BACKGROUND AND OBJECTIVE

We have previously reported elevated serum immunoreactive inhibin (INH) levels in patients with ovarian malignancies, particularly granulosa cell and mucinous tumours. The present study was designed to compare INH measurements using a heterologous radioimmunoassay with cross-reactivity for inhibin alpha-subunit derived peptides with measurements obtained using a new ELISA specific for dimeric inhibin-A. It was hypothesized that granulosa cell tumours may secrete significant quantities of inhibin-A whereas mucinous tumours were unlikely to do so because of the lack of a relation between INH and FSH measurements in the latter group.

DESIGN

Serum samples obtained from women found to have ovarian cancer were assayed using the heterologous radioimmunoassay (the Monash assay) and using an ELISA specific for dimeric inhibin (the Groome assay) and the results were compared.

PATIENTS

Samples for assay were available from 69 normal post-menopausal control women, 12 patients with mucinous tumours of the ovary, 26 with serous tumours, 7 with granulosa cell tumours and 8 with various other ovarian tumours. Patients were post-menopausal or had been subjected to bilateral oophorectomy at the time these samples were collected.

MEASUREMENTS

The Monash and Groome assays were carried out as described previously. The upper limit of normal for post-menopausal women in the Monash assay was 122 U/l and for the Groome assay was calculated to be 32 ng/l.

RESULTS

Among the 69 normal subjects, 4 were found to have elevated inhibin levels using the Monash RIA (133-190 U/l) and 4 were found to have elevated levels in the Groome ELISA (45.5-55.3 ng/l). Among 12 patients with mucinous tumours, 10 (83%) had elevated inhibin levels using the Monash assay but only 3 (25%) had elevated levels with the Groome assay (P < 0.005). Among 26 with serous tumours, 15 (58%) had elevated levels in the Monash assay but only 1 (4%) in the Groome assay (P < 0.001). Among 7 samples from patients with granulosa cell tumours, 100% were elevated in the Monash assay and 71% in the Groome assay (NS, non-significant). In a miscellaneous group of tumours all 8 had elevated levels in the Monash assay and 2 in the Groome assay (P < 0.001).

CONCLUSIONS

It was concluded that in normal postmenopausal subjects, INH is generally undetectable or present at low levels, consistent with the loss of ovarian function. The majority of granulosa cell tumours appear to secrete significant amounts of dimeric inhibin-A, whereas mucinous tumours secrete predominantly other forms of INH, presumably related to the alpha-subunit. Serous tumours may also secrete inhibin-related peptides but not dimeric inhibin-A. The nature of the inhibin related peptides produced by epithelial ovarian cancers remains to be characterized.