Molecular and physiological study of the artificial maturation process in European eel males: from brain to testis

European eel males can be artificially matured (1.5IU hCG/g fish), but the regulatory mechanisms of their reproductive development are practically unknown. Spermatogenic stages (S1-S6), biometric characters [eye index (EI), gonadosomatic index (GSI), hepatosomatic index (HSI)] and sperm quality parameters (motility, viability and head spermatozoa morphometry) were analysed. Moreover, the present study evaluated the expression of GnRHs (mammal and chicken II Gonadotropin Release Hormone I) and gonadotrophins (FSHbeta and LHbeta) during hormonal treatment, as well as 11-ketotestosterone (11-KT) and 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) plasma levels. One week was enough to observe the S2 of gonad development, but it was necessary to reach the 7th week of treatment to obtain animals that presented the most advanced stage of development (S6). Differential regulation of the two GnRH expressions was found, supporting the main role of mGnRH in the control of gonadotrophin release. One hCG injection was enough to dramatically decrease the FSHbeta expression, being close to zero during the rest of the treatment. LHbeta expression and 17,20beta-P registered a significant increase in the same stage of development, S3/4, confirming the role of this gonadotrophin in the last steps of maturation and 17,20beta-P in the spermatozoa maturation. The 11-KT increased with GSI, and the highest 11-KT values coincided with the advanced steps of spermatogenesis prior to spermiation. Being consistent with the known role of the steroid in these processes. Furthermore, this study supports a role for 11-KT in stimulating eye growth, presenting high values when EI increased. Sperm production was obtained from the 4th week of treatment, but it was in the 8th week when a significant increase was observed in sperm quality [viability, high motility (>75%)].

Proteomic profiles in hyperandrogenic syndromes

BACKGROUND

Polycystic ovary syndrome (PCOS) and congenital adrenal hyperplasia (CAH) represent the most common causes of hyperandrogenism. Although the etiopathogeneses of these syndromes are different, they share many clinical and biochemical signs, such as hirsutism, acne, and chronic anovulation. Experimental data have shown that peripheral T-lymphocytes function as molecular sensors, being able to record molecular signals either at staminal and mature cell levels, or hormones at systemic levels.

METHODS

Twenty PCOS women and 10 CAH with 21-hydroxylase deficiency, aged between 18-35 yr, were studied. T-cells purified from all patients and 20 healthy donors have been analyzed by 2-dimensional gel electrophoresis. Silver-stained proteomic map of each patient was compared with a control map obtained by pooling protein samples of the 20 healthy subjects.

RESULTS

Spots of interest were identified by peptide mass fingerprint. Computer analysis evidenced several peptidic spots significantly modulated in all patients examined. Some proteins were modulated in both syndromes, others only in PCOS or in CAH. These proteins are involved in many physiological processes as the functional state of immune system, the regulation of the cytoskeleton structure, the oxidative stress, the coagulation process, and the insulin resistance.

CONCLUSION

Identification of the physiological function of these proteins could help to understand ethiopathogenetic mechanisms of hyperandrogenic syndromes and its complications.

The role of the maturation-inducing steroid, 17,20beta-dihydroxypregn-4-en-3-one, in male fishes: a review

The major progestin in teleosts is not progesterone, as in tetrapods, but 17,20beta-dihydroxypregn-4-en-3-one (17,20beta-P) or, in certain species, 17,20beta,21-trihydroxy-pregn-4-en-3-one (17,20beta,21-P). Several functions for 17,20beta-P and 17,20beta,21-P have been proposed (and in some cases proved). These include induction of oocyte final maturation and spermiation (milt production), enhancement of sperm motility (by alteration of the pH and fluidity of the seminal fluid) and acting as a pheromone in male cyprinids. Another important function, initiation of meiosis (the first step in both spermatogenesis and oogenesis), has only very recently been proposed. This is a process that takes place at puberty in all fishes and once a year in repeat spawners. The present review critically examines the evidence to support the proposed functions of 17,20beta-P in males, including listing of the evidence for the presence of 17,20beta-P in the blood plasma of male fishes and discussion of why, in many species, it appears to be absent (or present at low and, in some cases, unvarying concentrations); consideration of the evidence, obtained mainly from in vitro studies, for this steroid being predominantly produced by the testis, for its production being under the control of luteinizing hormone (gonadotrophin II) and, at least in salmonids, for two cell types (Leydig cells and sperm cells) being involved in its synthesis; discussion of the factors involved in the regulation of the switch from androgen to 17,20beta-P production that seems to occur in many species just at the time of spermiation; discussion of the effects of in vivo injection and application of 17,20beta-P (and closely related compounds) in males; a listing of previously published evidence that supports the proposed new function of 17,20beta-P as an initiator of meiosis; finally, discussion of the evidence for environmental endocrine disruption by progestins in fishes.

The spectrum of phenotypes associated with mutations in steroidogenic factor 1 (SF-1, NR5A1, Ad4BP) includes severe penoscrotal hypospadias in 46,XY males without adrenal insufficiency

OBJECTIVE

Hypospadias is a frequent congenital anomaly but in most cases an underlying cause is not found. Steroidogenic factor 1 (SF-1, NR5A1, Ad4BP) is a key regulator of human sex development and an increasing number of SF-1 (NR5A1) mutations are reported in 46,XY disorders of sex development (DSD). We hypothesized that NR5A1 mutations could be identified in boys with hypospadias.

DESIGN AND METHODS

Mutational analysis of NR5A1 in 60 individuals with varying degrees of hypospadias from the German DSD network.

RESULTS

Heterozygous NR5A1 mutations were found in three out of 60 cases. These three individuals represented the most severe end of the spectrum studied as they presented with penoscrotal hypospadias, variable androgenization of the phallus and undescended testes (three out of 20 cases (15%) with this phenotype). Testosterone was low in all three patients and inhibin B/anti-Müllerian hormone (AMH) were low in two patients. Two patients had a clear male gender assignment. Gender re-assignment to male occurred in the third case. Two patients harbored heterozygous nonsense mutations (p.Q107X/WT, p.E11X/WT). One patient had a heterozygous splice site mutation in intron 2 (c.103-3A/WT) predicted to disrupt the main DNA-binding motif. Functional studies of the nonsense mutants showed impaired transcriptional activation of an SF-1-responsive promoter (Cyp11a). To date, adrenal insufficiency has not occurred in any of the patients.

CONCLUSIONS

SF-1 (NR5A1) mutations should be considered in 46,XY individuals with severe (penoscrotal) hypospadias, especially if undescended testes, low testosterone, or low inhibin B/AMH levels are present. SF-1 mutations in milder forms of idiopathic hypospadias are unlikely to be common.

Serum levels of steroid hormones in men with varicocele and oligospermia as compared to normozoospermic men

In order to assess the contribution of individual steroidogenic organs to over-all steroid biosynthesis, the basal plasma levels of six hormonal steroids, reflecting the function of gonads and adrenals, as well as both gonadotropins and prolactin, have been determined in 63 oligo- and/or asthenozoospermic men with palpable varicocele, confirmed in each case by sonography. The values obtained were compared with the results of a group of age-matched normospermic men without endocrine disorders. Insignificantly lower levels of testosterone accompanied by significantly lower levels of dihydrotestosterone, slightly decreased LH but increased FSH undistinguishable concentrations of cortisol in patients with varicocele were in agreement with previous findings. Higher levels of an exclusively adrenal androgen 11 beta-hydroxyandrostenedione in men with varicocele indicate increased activity of the adrenal cortex. Significantly higher basal levels of 17 alpha-hydroxyprogesterone in the patient group (p < 0.001), so far not unequivocally proved, evidence for suggested decreased enzyme activity of C17-20 lyase in the testis in at least some of men with varicocele.

Blood-spot 17-hydroxyprogesterone in nonclassical 21-hydroxylase deficiency

The value of blood-spot 17-hydroxyprogesterone (17-OHP) measurements in selective screening for non-classical 21-hydroxylase deficiency (NC 21-OHD) among female patients with postnatal virilization was studied. Early morning basal blood-spot and serum samples, and post-ACTH serum samples for 17-OHP measurement were collected from twenty-seven patients with precocious pubarche, hirsutism and/or menstrual abnormalities (age: 3 to 17 years). Using a two-step extraction method for blood-spot 17-OHP measurements of all the nine patients with NC 21-OHD showed higher values than the eighteen patients without 21-OHD. Blood-spot 17-OHP values of patients with NC 21-OHD showed a diurnal rhythm with pathological high levels between 0500 and 0900 h, and normal or slightly elevated levels between 1700 and 2100 h. In conclusion, early morning blood-spot 17-OHP measurement is a useful method to detect NC 21-OHD in the peripubertal period.

Changes in the immunostaining intensities of follicle-stimulating hormone and luteinizing hormone during ovarian maturation in the female Japanese flounder

The role of gonadotropin (GTH) in the reproduction of the Japanese flounder, Paralichthys olivaceus, was studied by assessing the changes in the apparent activity of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the pituitary gland during gonadal maturation by immunohistochemical analyses. Corresponding changes in plasma levels of testosterone (T), estradiol-17beta (E(2)), and 17alpha,20beta-dihydroxy-4-pregnen-3-one (DHP) were also studied. Reared fish at the early spawning to termination stages were sampled from May to August and wild fish at the previtellogenic to termination stages were caught at 3- to 4-week intervals between April and September offshore from the northern mainland of Japan by gill nets. The gonadosomatic index of the reared fish decreased from the early spawning stage to the termination stage, while that of the wild fish increased significantly from the previtellogenic stage to the early spawning stage and decreased thereafter. In the reared fish, the immunostaining intensities of FSH and LH were high during the spawning period, accompanied by high plasma levels of T, E(2), and DHP. In the wild fish, the immunostaining intensities of FSH and LH were low during the previtellogenic stage but increased during the maturing and spawning stages. These results indicate that both FSH and LH are likely associated with oocyte maturation in the Japanese flounder.

The combined effects of temperature and GnRHa treatment on the final stages of sexual maturation in Atlantic salmon (Salmo salar L.) females

Atlantic salmon (Salmo salar L.) females (2 SW), maturing for the first time, were reared under one of three temperature regimes (high: 14.3 +/- 0.5 degrees C; natural: 10.6 +/- 1.0 degrees C; and cold: 6.9 +/- 1.0 degrees C) in combination with one of two experimental treatments; an injection of GnRH analogue (GnRHa) contained in biodegradable microspheres, or a sham injection (microspheres only). The six experimental groups were then reared under simulated natural photoperiod for 4 weeks. Blood samples were drawn for analysis of plasma steroid levels and the fish were inspected for ovulation weekly. Batches of stripped eggs were incubated in triplicate incubators in raceways until the eyed stage. Treatment with GnRHa resulted in a substantial advancement and synchronization of ovulation at all temperatures, while exposure to cold water also appeared to advance ovulation slightly. While 75% (warm and cold) to 90% (natural) of GnRHa fish ovulated during the 4-week trial, only 30% of sham-treated females exposed to cold water, and none of the sham-treated fish held at higher temperatures, ovulated during this period. Survival rates of embryos to the eyed-stage were significantly higher for broodstock exposed to cold water. Plasma levels of testosterone (T), 17beta-oestradiol (E2), and 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20betaP) were all significantly affected by treatment with GnRHa and, to a lesser extent, temperature. The efficiency of GnRHa in counteracting the negative effects of high temperature on ovulation and the associated changes in circulating sex steroids suggest that temperature inhibition operates at least in part at the brain or pituitary.

Changes in brain seabream GnRH mRNA and pituitary seabream GnRH peptide levels during ovarian maturation in female barfin flounder

The pleuronectid barfin flounder Verasper moseri expresses three forms of gonadotropin-releasing hormones (GnRHs), i.e., seabream GnRH (sbGnRH), salmon GnRH, and chicken GnRH-II. Among these, sbGnRH is the dominant form in the pituitary, indicating that sbGnRH regulates gonadal maturation. In order to clarify the physiological roles of sbGnRH during ovarian maturation in reared female barfin flounder, the changes in brain sbGnRH mRNA levels and pituitary sbGnRH peptide levels were examined by real-time quantitative PCR and time-resolved fluoroimmunoassay, respectively. The fish hatched in April 2002. The gonadosomatic index remained low until August 2004 and increased thereafter until April 2005 when the fish began to ovulate. The sbGnRH mRNA levels per brain increased significantly from April 2004 to April 2005. Pituitary sbGnRH peptide levels also increased significantly during this period. These results indicate that sbGnRH is involved in ovarian maturation and ovulation in the barfin flounder.

A progestin and an estrogen regulate early stages of oogenesis in fish

Using two species of teleost fish, Japanese huchen (Hucho perryi) and common carp (Cyprinus carpio), we investigated whether sex steroids are involved in early oogenesis in vitro. Ovarian fragments were cultured to examine the effects of a progestin, 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP), and an estrogen, estradiol-17 beta (E2). DHP and E2 significantly promoted DNA synthesis in ovarian germ cells, as judged by 5-bromo-2-deoxyuridine (BrdU) incorporation into these cells. Furthermore, to detect the initiation of the first meiotic division of early oogenesis, we assessed ultrastructurally the occurrence of synaptonemal complexes (SCs) and analyzed by immunohistochemistry the expression of a meiosis-specific marker, Spo11. In huchen, a higher percentage of oocytes with SC was seen in DHP-treated ovarian fragments than in control or E2-treated ovarian fragments. Spo11 was expressed in germ cells after DHP treatment of carp ovarian explants. These data suggest that the progression of germ cells through early oogenesis involves two sex steroids: E2, which acts directly on oogonial proliferation, and DHP, which acts directly on the initiation of the first meiotic division of oogenesis.

Treatment of GnRHa-implanted Senegalese sole (Solea senegalensis) with 11-ketoandrostenedione stimulates spermatogenesis and increases sperm motility

The effect of 11-ketoandrostenedione (OA) on plasma concentrations of sexual steroids and spermatogenesis of Senegalese sole (Solea senegalensis) implanted with gonadotropin-releasing hormone agonist (GnRHa) was investigated. Males were treated with saline (control) or with GnRHa implants (50 mug kg(-1)) in the presence or absence of OA (2 or 7 mg kg(-1)) during twenty eight days. Treatment with GnRHa alone slightly stimulated spermatogenesis and milt production with respect to controls, and this was associated with a transient elevation of plasma 11-ketotestosterone (11-KT) at day seven and an increase of 5beta-reduced metabolite(s) of 17,20beta-dihydroxy-pregn-4-en-3-one (17,20betaP) at day twenty eight. However, treatment with GnRHa+OA increased plasma concentrations of 11-KT and free+sulphated 5beta-reduced metabolites of 17,20betaP at days seven, fourteen and twenty one. After twenty eight days, the testis of GnRHa+OA-treated fish showed a lower number of spermatogonia B and spermatocytes I, and a higher number of spermatids, than fish treated with GnRHa alone. In addition, the motility of spermatozoa produced by GnRHa+OA males was enhanced by 2-fold with respect to controls or GnRHa males. These results suggest that treatment of Senegalese sole with GnRHa+OA stimulates spermatogenesis resulting in more motile sperm. Such effects could be mediated by an increased synthesis of 11-KT and/or 17,20betaP in the testis but further studies will be required to elucidate the specific mechanism involved.

Effects of a pyrethroid pesticide on endocrine responses to female odours and reproductive behaviour in male parr of brown trout (Salmo trutta L.)

Reproductive behaviour of brown trout (Salmo trutta L.) from an anadromous stock was studied in a large stream water aquarium. Four adult males and two ovulated females were placed in the aquarium together with eight mature male parr. Four of the parr were exposed during the previous 4 days to two concentrations (0.1 or 1.0 microgl(-1)) of the pyrethroid pesticide cypermethrin (a disrupter of olfactory receptor function) and four of the parr to the solvent ethanol. The behaviour of all fish was followed for 24h and then blood and milt was collected. Exposure to the higher concentration of cypermethrin disturbed the reproductive behaviour of the parr. They displayed fewer courting events, spent less time near the nesting females and had lower volumes of strippable milt. They also had significantly lower amounts of 11-ketotestosterone (11-KT) in the blood plasma than the control group. The higher cypermethrin group also had significantly lower levels of all these variables than the lower cypermethrin group, apart from strippable milt that showed no significant differences between two groups. No significant differences in non-reproductive behaviours were observed between any of the groups. In the control fish, there were significant positive correlations between (a) the number of courting events and the amount of time spent near the female, (b) blood plasma levels of 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) and time spent near the female and (c) plasma levels of 17,20beta-P and the number of courting events. Further, in control fish, higher plasma levels of 17,20beta-P were observed in parr interacting with a female compared to those with no female contacts. A priming experiment confirmed a previous study that cypermethrin damages olfactory reception. Parr exposed to cypermethrin had significantly lower blood plasma levels of 17,20beta-P and 11-KT than control males after exposure to ovarian fluid and urine (known to contain reproductive priming pheromones). When ethanol-exposed males were exposed to ovarian fluid and urine they had significantly higher plasma levels of 17,20beta-P compared to those exposed to water only.

Testicular development and plasma sex steroid levels in cultured male Senegalese sole Solea senegalensis Kaup

Testicular development and plasma levels of sex steroids (11-ketotestosterone (11-KT), testosterone (T) and 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P)) were investigated for the first time in cultured male Senegalese sole Solea senegalensis. The germ cell dynamics and gonadosomatic index (IG) were monitored. Based on the relative abundance of the different types of germ cells present, the spermatogenetic cycle was divided into five stages: early (I; spermatogonia (SPG)), mid (II; SPG, spermatocytes (SPC) and spermatids (SPD)), and late spermatogenesis (III; SPC, SPD, and spermatozoa (SPZ)), functional maturation (IV; SPD and SPZ), and recovery (V; SPD, SPZ, and SPG). During summer, fish had stage I and V testes and the lowest values in plasma levels of sex steroids and IG. Testicular recrudescence seemed to begin in autumn, as denoted by the first increase in IG and in the levels of 11-KT and T, and the appearance of testes at stage II and III. During winter, the levels of 11-KT and T peaked and soon began to decrease, the IG slightly declined and the proportion of running males (RM) gradually increased. In spring, levels of 11-KT and T continued to decline, the IG slightly increased and the proportion of RM peaked concomitantly with the occurrence of stage IV testes. Plasma levels of 17,20beta-P did not change significantly throughout testicular development. Transformation of SPD into SPZ followed a group-synchronous fashion, a phenomenon which parallels asynchronous oocyte development reported in females. This mechanism would be consistent with the observed small quantity of sperm that can be manually stripped at any one time and other aspects of S. senegalensis reproductive biology.

Rapid adjustments of sperm characteristics in relation to social status

Sperm competition models predict that males typically mating in disfavoured roles should be selected to compensate for their disadvantage by investing more into sperm. We studied the effect of rapid changes in social status on ejaculate investments during experimental trials with an externally fertilizing teleost--the Arctic charr (Salvelinus alpinus). We document that males becoming dominant produce less sperm with lower velocity, but have higher sex steroid concentrations than subordinate males. These differences in sperm characteristics seem mainly to result from a decreased investment in sperm among fish that become dominant compared to pre-trial levels. Moreover, these adjustments of sperm production and sperm velocity seem not to be traded against sperm longevity. Our results support theoretical models of sperm competition, as males forced to mate in disfavoured roles seem to invest more into ejaculate quality than males in favoured roles. Additionally, we are the first to report that males, in a species with status-dependent shifts in reproductive tactics, have evolved rapid tactic specific adjustments of sperm production and sperm velocity corresponding to what could be predicted from their reproductive roles.

Large differences in testosterone excretion in Korean and Swedish men are strongly associated with a UDP-glucuronosyl transferase 2B17 polymorphism

CONTEXT

The reproductive endocrinology in Asians and Caucasians is of great interest in view of large differences in prostate cancer rate and sensitivity to pharmacological male contraception. In addition, interpretation of certain antidoping tests is confounded by interethnic variation in androgen disposition. Uridine diphosphoglucuronosyl transferases have a key role in the homeostasis and metabolism of androgens. Recently a deletion polymorphism was detected in the UGT2B17 gene.

OBJECTIVE

The objective of the study was to evaluate the contribution of the UGT2B17 deletion polymorphism to the interindividual and interethnic variation of androgen metabolism and excretion.

METHODS AND RESULTS

Urine from 122 Swedish and 74 Korean healthy men was analyzed for several androgen glucuronides including testosterone. The distribution of the natural logarithms of urinary testosterone concentrations showed a distinct bimodal pattern in both groups, suggesting a monogenic inheritance. When the UGT2B17 genotypes were compared with urinary testosterone levels, all of the individuals of the UGT2B17 homozygous deletion/deletion genotype had no or negligible amounts of urinary testosterone. The deletion/deletion genotype was seven times more common in the Korean (66.7%) than the Swedish population (9.3%). In addition, the Swedes had significantly higher levels of serum testosterone, compared with the Koreans.

CONCLUSIONS

Our results show that the UGT2B17 polymorphism is strongly associated with the bimodal distribution of the testosterone excretion and also with the large differences in testosterone excretion between Koreans and Swedes.

Detection of 17alpha-hydroxyprogesterone caproate in equine plasma by gas chromatography/tandem mass spectrometry

A method was developed for the analysis of the synthetic progestin 17alpha-hydroxyprogesterone caproate in equine plasma following its administration by intramuscular injection. The method employed a reversed-phase solid-phase extraction followed by enol-trimethylsilylation and analysis by gas chromatography/tandem mass spectrometry. The intact ester was detectable in the plasma for up to 2 weeks after a single therapeutic dose, and was found to be stable in equine whole blood for at least 2 months.

Steroidogenesis in ovarian follicles of chub mackerel, Scomber japonicus

We incubated different radiolabeled steroid precursors with intact chub mackerel ovarian follicles to clarify the synthetic pathways of steroid hormones during vitellogenesis and following final oocyte maturation (FOM). During vitellogenesis, estradiol-17beta (E2) was synthesized from pregnenolone via 17-hydroxypregnenolone, 17-hydroxyprogesterone, androstenedione, and testosterone. The physiological significance of the intermediate metabolites of E2 in the ovarian follicles was examined by comparing follicular steroidogenesis between gonochoric and hermaphroditic fish species. After vitellogenesis, the steroidogenic pathway shifted from E2 to maturation-inducing hormone (MIH) production owing to the inactivation of 17,20-lyase and the activation of 20 beta-hydroxysteroid dehydrogenase. Of the new steroids produced during FOM, 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) was most effective at inducing germinal vesicle breakdown in vitro. Circulating levels of 17,20beta-P increased specifically around the time of germinal vesicle migration, while another FOM-specific 20beta-hydroxylated progestin, 17,20beta,21-trihydroxy-4-pregnen-3-one, was present at consistently low levels during FOM. These results indicate that 17,20beta-P is the MIH of chub mackerel.

Changes in bovine luteal progesterone metabolism in response to exogenous prostaglandin F(2alpha)

An experiment was conducted to determine the effect of prostaglandin F2alpha (PGF2alpha) on luteal synthesis of progesterone (P4) and related progestins. Sixteen beef heifers were assigned in equal numbers to four groups in a 2x2 factorial arrangement of treatments. The experiment consisted of two levels of PGF2alpha analog (0 and 500 microg) and two levels of time (4 and 24 h after injection) of corpus luteum collection. All heifers were injected intravenously with saline (2 ml) or PGF2alpha (cloprostenol) on day 8 of the estrous cycle (estrus=day 0). Jugular blood was collected at 0, 1, 2, 3, 4 and 20, 21, 22, 23, and 24 h after injection. Resulting sera were analyzed for P4 by use of radioimmunoassay. Luteal tissue was analyzed by gas chromatography/mass spectrometry for P4, 20beta-hydroxyprogesterone, pregnenolone, and allopregnanolone (3beta-hydroxy-5alpha-pregnan-20-one). Treatment with PGF2alpha reduced serum concentrations of P4 as early as 1 h after injection (P<0.005) and steroid levels remained low over 24 h. Similarly, administration of PGF2alpha caused a decline in luteal P4 (P<0.005), 20beta-hydroxyprogesterone (P<0.10), and pregnenolone (P<0.05). In contrast, treatment with PGF(2alpha) caused an increase in luteal allopregnanolone over time (time x treatment interaction; P<0.05). These data are interpreted to suggest that PGF2alpha promotes conversion of P4 to the metabolite allopregnanolone.

15Alpha-hydroxyprogesterone in male sea lampreys, Petromyzon marinus L

There is growing evidence that sea lampreys, Petromyzon marinus L., produce gonadal steroids differing from those of other vertebrates by possessing an additional hydroxyl group at the C15 position. Here we demonstrate that sea lamprey testes produce 15alpha-hydroxyprogesterone (15alpha-P) in vitro when incubated with tritiated progesterone, that 15alpha-P is present in the plasma of sea lampreys, and that plasma concentrations of immunoreactive (ir) 15alpha-P rise dramatically in response to injections of gonadotropin-releasing hormone (GnRH). The identity of the tritiated 15alpha-P produced in vitro was confirmed by co-elution with standard 15alpha-P on high performance liquid chromatography, co-elution with standard and acetylated 15alpha-P on thin layer chromatography, and specific binding to antibodies raised against standard 15alpha-P. The in vitro conversion was used to produce tritiated 15alpha-P label for a radioimmunoassay (RIA), which is able to detect 15alpha-P in amounts as low as 2 pg per tube. The RIA has been used to measure the plasma concentrations of 15alpha-P in males given two serial injections, 24 h apart, of either lamprey GnRH I or GnRH III (50, 100, or 200 microg/kg) or saline control, with plasma being sampled 8 and 24 h after the second injection. Plasma concentrations of ir-15alpha-P rose from < 1 to 36 ng/ml (mean of all treatments) 8 h after injection and declined within 24 h. This is the first time that an RIA has detected such high steroid concentrations in lampreys. This finding is suggestive of a role for 15alpha-P in control of reproduction in the sea lamprey.

Serum 17,20β-dihydroxy-4-pregnen-3-one Levels in Pregnant and Non-pregnant Female Rockfish, Sebastes schlegeli, Viviparous Teleost, and its Production by Post-ovulatory Follicles

Changes in serum 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-DP) levels around the gestation time of normal pregnant and experimentally non-pregnant females were investigated in the black rockfish, Sebastes schlegeli, a viviparous teleost. The serum 17,20 beta-DP in both females showed similar changes and levels, increasing from the early to late gestation periods and declining just before parturition in pregnant females and egg-release in non-pregnant females, respectively. These results suggest that the maintenance of high serum levels of 17,20 beta-DP after oocyte maturation is not correlated with gestation or parturition, but occurs spontaneously in this species. The decline of 17,20 beta-DP levels prior to egg-release in non-pregnant females tended to occur one week earlier than those prior to parturition in pregnant females, suggesting that both a decline in 17,20 beta-DP levels in mothers and some response from embryos are needed for a smooth parturition. The post-ovulatory follicles were maintained throughout the gestation period and produced a considerable amount of 17,20 beta-DP in vitro (3.44-6.96 pg/ml/mg tissue), but little estradiol-17beta (0.92-1.66 pg/ml/mg tissue). The production of 17,20 beta-DP tended to be enhanced by the addition of a precursor steroid, pregnenolone, in the pre-, early and mid-gestation periods. These results strongly suggest that the follicle cells in black rockfish have the ability to synthesize 17,20 beta-DP during the post-ovulatory period, and high serum 17,20 beta-DP during gestation is supplied by the post-ovulatory follicles, which in Sebastes are considered to be functionally homologous to the mammalian corpus luteum.

Adrenocortical adenoma associated with inadequately treated congenital adrenal hyperplasia

We report a 6 year-old boy with the simple virilizing form of 21-hydroxylase deficiency in whom an adrenal adenoma developed following 5 years of steroid treatment. Extremely high levels of basal serum 17alpha-hydroxyprogesterone as well as an exaggerated response of 17alpha-hydroxyprogesterone to adrenocorticotropic hormone confirmed congenital adrenal hyperplasia at 7 years of age. Initially elevated serum steroid levels were restrained by high dose hydrocortisone therapy, but he chronically tended to take inadequate doses of glucocorticoid. At 12 years of age an adenoma was found in the cortex of the hyperplastic right adrenal gland. The importance of early diagnosis and compliance with medication in the simple virilizing form of 21-hydroxylase deficiency is stressed.

Endocrine correlates of intra-specific variation in the mating system of the St. Peter's fish (Sarotherodon galilaeus)

The Challenge Hypothesis postulates that androgen levels are a function of the social environment in which the individual is living. Thus, it is predicted that in polygynous males that engage in social interactions, androgen levels should be higher than in monogamous animals that engage in parental care. In this study, we tested this hypothesis at the intra-specific level using a teleost species, Sarotherodon galilaeus, which exhibits a wide variation in its mating system. Experimental groups of individually marked fish were formed in large ponds with different operational sex-ratios (OSR) to study the effects of partner availability on blood plasma levels of sex steroids [11-ketotestosterone (11-KT), testosterone (T), and 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P)] and gonadosomatic index (GSI). Polygyny mostly occurred in the female biased OSR groups. 17,20beta-P and gonadosomatic index did not differ among OSR groups. However, 11-KT was high in male biased OSR and positively correlated with aggressive challenges, thereby supporting the central postulate of the Challenge Hypothesis. The results of T were the inverse of those of 11-KT, probably because 11-KT is metabolized from T. 11-KT levels of polygynous males did not differ neither from those of monogamous males, nor from those of males that participated in parental care. These results do not support the expected relationships between polygyny, parental care, and androgen levels. The differences from expectations for 11-KT may be related to the fact that in S. galilaeus, the mating and the parenting phase are not clearly separated and thus, males may still fight and court while they are brooding.

Year-to-year differences in plasma levels of steroid hormones in pre-spawning chum salmon

Changes in plasma levels of steroid hormones in pre-spawning chum salmon (Oncorhynchus keta) were examined for 6 years in association with sexual maturation. Fish were sampled along their homing pathway from the coastal sea to the spawning ground from 1995 to 2000. Plasma levels of testosterone (T), 11-ketotestosterone (11KT), estradiol-17beta (E2), 17alpha,20beta-dihydroxy-4-pregnen-3-one (DHP), and cortisol were determined by enzyme immunoassays. Sexual maturity was comprehensively estimated by gonadosomatic indices, histology of gonads, nuptial color, spermiation or ovulation ratio. Since the plasma levels of steroid hormones and sexual maturation differed from year to year, they were compared with year-to-year variation of sea surface temperature (SST) of coastal sea to study influence of oceanographic environment on these physiological data. The SST of the migratory route varied among the years, so that we classified the 6 years into cool, intermediate, and warm years. Concerning maturity, the males that returned to the natal hatchery in the warm years were sexually more advanced than those in the cool years. Furthermore, histological data suggested that final oocyte maturation occurred before arrival at the hatchery in one of the warm years, i.e., 1999, while it occurred at the hatchery in one of the intermediate years, i.e., 2000. In the males, T and 11KT levels increased significantly on midway of the homing route in the warm years, whereas they did not show any noticeable changes in the cool years. Furthermore, the levels of T and 11KT on midway of the homing route in the warm years, i.e., 1998 and 1999, were significantly higher than those in one of the cool years, i.e., 1995, in both sexes. In the females, the levels of E2 decreased during upstream migration. Conversely, those of DHP considerably elevated at spawning ground in all years examined. The levels of cortisol were different from year to year regardless of the SST. The present results showed that there were year-to-year differences in plasma levels of steroid hormones and maturity, and some of them may be influenced by the year-to-year variation of SST.

Short-term exposure to 17 alpha-ethynylestradiol decreases the fertility of sexually maturing male rainbow trout (Oncorhynchus mykiss)

The synthetic estrogen 17 alpha-ethynylestradiol (EE2) is a commonly used oral contraceptive that has been increasingly detected in sewage effluents. This study determined whether EE2 exposure adversely affected reproduction in sexually maturing male rainbow trout (Oncorhynchus mykiss). We exposed male trout to graded water concentrations of EE2 (10, 100, and 1,000 ng/ L) for 62 d leading up to the time of spawning. Semen and blood plasma samples were removed from each fish. Semen was used to fertilize groups of eggs from one nonexposed female. As a measure of fertility, eggs were incubated for 28 d after fertilization to determine the proportion that attained the eyed stage of embryonic development. Additional endpoints also measured included sperm motility, spermatocrit, gonadosomatic and hepatosomatic indices, testis histology, and circulating plasma levels of the sex steroids 17 alpha, 20 beta-dihydroxyprogesterone (17,20-DHP) and 11-ketotestosterone (11-KT). Exposure to 1,000 ng/L of EE2 caused complete mortality of the treatment group by day 57. Exposure to lower EE2 water concentrations (10 and 100 ng/L) caused an increase in sperm density, while a significant reduction in testis mass was observed only in the 100-ng/L exposure group. Most significantly, semen harvested from fish exposed to 10 and 100 ng/L EE2 caused an approximately 50% reduction in the number of eggs attaining the eyed stage of embryonic development. Plasma levels of 17,20-DHP in exposed fish were roughly twice the level of the controls, while levels of 11-KT were significantly reduced in fish exposed to 100 ng/L EE2. These results suggest that sexually maturing male rainbow trout are susceptible to detrimental reproductive effects of short-term exposures to environmentally relevant levels of EE2.

Changes in expression of genes encoding gonadotropin subunits and growth hormone/prolactin/somatolactin family hormones during final maturation and freshwater adaptation in prespawning chum salmon

The pituitary levels of mRNAs encoding gonadotropin (GTH) subunits (GTH alpha2 and IIbeta), prolactin (PRL), and somatolactin (SL) increased in chum salmon during the last stages of spawning migration. In the present study, changes in pituitary levels of mRNAs encoding GTH alpha2, Ibeta, and IIbeta; growth hormone (GH); PRL; and SL were examined in homing chum salmon of Sanriku stock to clarify whether the changes are associated with final maturation or freshwater (FW) adaptation. In 1993, fish were caught at four areas: off the coast of Sanriku (off-coast), the mouth of Otsuchi Bay (ocean), inside of Otsuchi Bay (bay), and the Otsuchi River (river). In addition, effects of hypoosmotic stimulation by transition from seawater (SW) to FW were examined in 1994 and 1995. The amounts of mRNAs were determined by dot-blot analyses or real-time polymerase chain reactions. The levels of GTH alpha2 and IIbeta mRNAs in the ocean, bay, and river fish were two to five times those in the off-coast fish, and the levels of SL mRNAs in the bay fish were two to four times those in the off-coast fish. The levels of GH and PRL mRNAs in the ocean and bay fish were significantly lower than those in the off-coast fish, and those in the river fish were three to five times those in the ocean and bay fish. In the SW-to-FW transition experiment in 1994, the levels of GTH alpha2, Ibeta, and IIbeta mRNAs transiently increased, whereas changes were insignificant in 1995. The levels of GH, PRL, and SL mRNAs increased in both SW and FW environments, and no apparent effects of SW-to-FW transition were observed. The present study suggests that in prespawning chum salmon, expression of genes encoding GTH alpha2, IIbeta, and SL elevates with final maturation regardless of osmotic environment. Hypoosmotic stimulation by transition from the SW-to-FW environment is not critical to modulate expression of genes for PRL. PRL gene expression can be elevated in SW fish that were sexually almost matured.