On the existence and separation of the follicle stimulating hormone releasing hormone from the luteinizing hormone releasing hormone

Hormonal treatment for prostate cancer

For nearly six decades the preferred primary treatment for advanced prostate cancer has been continuous suppression of testicular androgen production by medical or surgical castration. While androgen deprivation is effective in inducing tumour regression in the large majority of cases, essentially all patients will develop progressive disease. In addition androgen deprivation may be associated with a variety of side effects. Thus, strategies that minimise the use of these agents could potentially lower the morbidity and cost associated with the treatment of advanced prostate cancer. In the era of prostate-specific antigen (PSA) testing, hormonal therapy is being used earlier in the course of the disease when the only evidence of recurrent disease is an elevated PSA. These men may survive for many years and thus have the potential for long periods of exposure to hormonal therapy and its side effects. It has been hoped that the development of alternative hormonal interventions might lead to both enhanced antitumour efficacy as well as improvements in side effect profile.

Luteinizing hormone and follicle stimulating hormone secretion patterns in girls throughout puberty measured using highly sensitive immunoradiometric assays

Pulsatile gonadotrophin secretion patterns were studied in 36 healthy girls by measuring every 10 min and applying immunoradiometric assays (IRMA). Different stages of puberty were associated with significant changes in the plasma LH and FSH levels, pulse numbers (Pno) and pulse amplitudes (pA). Plasma LH was not detectable by day or night in young prepubertal girls (B1), neither was plasma oestradiol (E2); however, plasma FSH was detectable in a pulsatile pattern. In the older prepubertal girls (B1-onset) a discrete pulsatile LH pattern became detectable only during the night; plasma FSH tended to rise, while E2 became just detectable. In the early pubertal girls (B2) most daytime LH values were above the detection limit, in some with low-amplitude pulses. At night, pulses with a wide range of pulse amplitudes were detected. Plasma FSH increased further, plasma E2 only slightly. With the progression of puberty the plasma LH and FSH levels, Pno and pA increased significantly from stage B2 to B3 during the day (P less than or equal to 0.05) and close to significance during the night (0.05 less than or equal to P less than or equal to 0.1). However, in stage B4 the secretory characteristics tended to decline, while from stage B3 onwards plasma E2 started to rise rapidly (P less than or equal to 0.05, during the night from stage B2 to B3, during the day from B3 to B4m-). Simultaneous LH and FSH pulses were observed throughout puberty, usually during the night. Using these IRMA methods nocturnal LH in older prepubertal girls and both diurnal and nocturnal FSH pulsatility could be demonstrated in young prepubertal girls. From this study we conclude that (1) puberty in girls, as in boys, may be brought about by an increasing GnRH secretion both in frequency and amplitude, first appearing during the night. This increased GnRH stimulation results in LH secretion only during the night; (2) a cyclical pulsatile LH pattern including an LH surge can be established before the menarche; the capacity for positive feedback activity is not the final maturation characteristic to achieve an ovulatory menstrual cycle.

Inhibin and related proteins: localization, regulation, and effects

Inhibin has originally been defined as a gonadal hormone that exerts a specific negative feedback action on the secretion of FSH from the gonadotropic cells of the pituitary gland. The existence of inhibin was postulated by Mottram and Cramer (15) as early as 1923. However, only after reliable and sensitive bioassay systems had been developed for detection and estimation of inhibin and an ample source of inhibin was found in the form of ovarian follicular fluid, was progress made on the isolation and characterization of the hormone. It is apparent now that inhibin, which itself consists of a dimer of two different subunits, alpha and beta, is a member of a much larger family of (glyco)protein hormones and growth factors that includes Müllerian inhibiting substance, transforming growth factor-beta, activin/erythroid differentiation factor, bone morphogenetic proteins, and an insect and a Xenopus protein. All play important roles in cell differentiation. Gonadal inhibin is produced in the Sertoli cells in the testis and in the granulosa cells in the ovary. The production of inhibin is stimulated by FSH, but controversy exists about other factors that might play a role in the regulation of the production of inhibin. It appears likely that inhibin plays an important role in the feedback regulation of peripheral concentrations of FSH during the period in which Sertoli cells and granulosa cells--the target cells for FSH--divide, i.e., during puberty in male animals and during the development of ovarian follicles in female animals. In this way, inhibin may be an important regulator of the number of developing Sertoli cells and of the length of the seminiferous tubuli in the testis and of the number of developing follicles in the ovary. Apart from its function in the pituitary-gonadal axis, inhibin and activin may be produced and act in a number of other organs such as the placenta, hypothalamus, adrenal, and bone marrow. Investigation of the role of the members of the inhibin family in these systems has only begun, but will certainly be a field of major interest in the near future.

Luteinizing hormone and follicle stimulating hormone secretion patterns in boys throughout puberty measured using highly sensitive immunoradiometric assays

Pulsatile gonadotrophin secretion patterns were studied in 32 normal boys (chronological age, CA 7.2-14.6 years) at different stages of pubertal development (5 in stage G1, 11 in G2, 5 in G3, 4 in G4, 7 in G5). Plasma LH and FSH concentrations were measured at 10 min intervals from 1200 to 1800 h and from 2400 to 0600 h using an immunoradiometric assay with a lower limit of detection of 0.15 IU/l for both LH and FSH. Plasma testosterone (T) was measured hourly. In the young prepubertal boys plasma LH was not detectable during day or night. In contrast, plasma FSH ranged from 0.7 to 1.4 IU/l. Plasma T was not detectable either (less than 0.25 nmol/l). In the older prepubertal boys a discrete pulsatile LH pattern (2 per 6 h) became discernible only during the night (range 0.1-0.4 IU/l). Plasma FSH also revealed a pulsatile pattern only during the night (2 per 6 h), while plasma T still remained undetectable. In the early pubertal boys (G2) a median daytime LH value of 0.37 IU/l was determined with 1 pulse per 6 h and at night definite LH pulses (4 per 6 h) were found in all boys (range 0.4-4.7 IU/l). Plasma FSH increased considerably to a median level of 2.50 IU/l during the day; most boys had a pulsatile FSH pattern (one per 6 h). Plasma T became detectable during the day (median 0.54 nmol/l) and night (median 1.16 nmol/l). With the progression of puberty the mean plasma level of LH and FSH, the LH/FSH pulse number and the LH/FSH pulse amplitude increased; plasma T rose as well, more obviously during the night. In G5, however, the LH pulse number decreased, while the LH level and pulse amplitude still increased, presumably as a result of the increased negative feedback action of sex steroids. Simultaneous LH/FSH pulses developed during the night at onset of puberty but during the day only towards the end of pubertal development. The use of these novel highly sensitive IRMA methods demonstrated nocturnal LH and both diurnal and nocturnal FSH pulsatility to be present in older prepubertal boys. The early detectable FSH level plus the existence of solitary FSH pulses throughout puberty as well as in adult men support the hypothesis of the existence of a GnRH-independent FSH secretion in men. Our results are in accordance with the following hypotheses: (1) puberty is brought about by GnRH secretion increasing with time, both in frequency and amplitude, and first appearing during the night.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification of a bioactive FSH-releasing factor (FSHRF)

Before the advent of radioimmunoassay (RIA), FSH-releasing factor (FSHRF) appeared to be separable from LH-releasing hormone (LHRH) by chromatography followed by bioassay for FSH. In this study, we re-examined hypothalamic extracts for the existence of an FSHRF distinct from LHRH, utilizing the Steelman-Pohley bioassay as well as RIA for identification of FSH. Acid extracts of rat hypothalamic fragments were chromatographed on Sephadex G-25. LH- and FSH-releasing activities of each fraction were assessed by bio- and immunoassay of FSH and immunoassay of LH released after incubation with hemipituitaries from adult male rats. The immunoreactive LHRH(IR-LHRH) concentration of each fraction was also measured by RIA. In order to evaluate the FSH-releasing activity of LHRH, three doses of synthetic LHRH were tested and FSH-releasing activity determined by bio- and immunoassay. By RIA, the FSH-releasing activity of each column fraction could be accounted for by IR-LHRH contamination. However, greater FSH-releasing activity than could be predicted by IR-LRH contamination was detected by Steelman-Pohley assay in fractions eluted prior to the LHRH peak in 2 separate fractionations. These fractions from the second fractionation were pooled and eluted from a CMC column with ammonium acetate buffers. Again greater FSH-releasing activity than could be accounted for by IR-LHRH was detected prior to the IR-LHRH peak by Steelman-Pohley assay. These results agree with early work from our laboratory and suggest the presence of a bioactive FSHRF in hypothalamic extracts.