Plasma Steroid Concentrations Research Articles

Endogenous Steroids Measured by High-Specificity Liquid Chromatography-Tandem Mass Spectrometry and Prevalent Cardiovascular Disease in 70-Year-Old Men and Women

There is a need for increased knowledge about endogenous sex hormone levels and clinical outcomes of risk/benefit. Immunoassays have poor specificity to reliably measure low steroid concentrations in elderly. The objective of the study was to evaluate plasma steroid concentrations with regard to prevalent cardiovascular disease (CVD) in elderly, using mass spectrometry. The study was conducted at a university hospital research unit. Plasma samples were analyzed from 202 70-yr-olds as part of a large population-based study, Prospective Investigation of the Vasculature in Uppsala Seniors. Twenty-eight of these had prevalent CVD. Eleven steroids were quantified, using liquid chromatography-tandem mass spectrometry. Women with current/previous menopausal hormone therapy (n = 35) were excluded. Men without prevalent CVD had higher plasma 17beta-estradiol (E2), compared with women. Men with prevalent CVD, compared with those without, had lower 17-hydroxypregnenolone (17OHPregn), 17-hydroxyprogesterone, and higher estrone/androstenedione and E2/testosterone (T) (aromatase activity). Women with prevalent CVD had lower pregnenolone, 17OHPregn, and dehydroepiandrosterone (DHEA) but higher DHEA/17OHPregn, androstenedione/DHEA, E2/T, E2/estrone, and E2/SHBG. The aromatase index, E2/T, was higher for prevalent CVD in both sexes. Adjustment for statin use, smoking, and body mass index yielded additional significant differences in men, whereas some were lost in women. Logistic regression indicated strong associations between prevalent CVD and low 17OHPregn, adjusted odds ratio of 0.18, 95% confidence interval (0.06-0.61); P = 0.006, in women and low 17-hydroxyprogesterone, 0.45 (0.25-0.80); P = 0.007 in men, most likely caused by increased throughput (consumption) toward estrogen synthesis. Prevalent CVD was associated with indications of lower androgen precursors, increased aromatase activity, and higher estrogen levels in both sexes. Results might represent an endogenous response to a condition of developing atherosclerosis, rather than a causative relationship. Furthermore studies are needed.

Aluminum as an endocrine disruptor in female Nile tilapia ( Oreochromis niloticus)

The effects of aluminum on plasma ion, lipid, protein and steroid hormone concentration were evaluated in Oreochromis niloticus broodstock females. Lipid and protein concentrations from the gonads and liver were also measured. Experiments were performed at neutral and acidic water pH. Four groups of fish were tested for 96 h: 1) control conditions at neutral water pH; 2) control conditions at acidic water pH (CTR-Ac); 3) aluminum at neutral water pH (Al-N); and 4) aluminum at acidic water pH (Al-Ac). Aluminum and acidic water pH exposure caused no ionoregulatory disturbances. Total lipid concentration increased in the mature gonads and decreased in the liver, suggesting an acceleration of lipid mobilization to the ovaries in animals exposed to aluminum. However, a decreased protein concentration in ovaries was also observed. Exposure of control fish to acidic water pH caused an increased concentration of plasma 17α-hydroxyprogesterone. However, females exposed to aluminum at acidic water pH showed a decreased of plasma 17α-hydroxyprogesterone and cortisol. No differences in plasma 17β-estradiol were observed. The physiological mechanisms underlying the disturbances observed are discussed focusing on reproduction. We suggest that aluminum can be considered an endocrine disrupting compound in mature O. niloticus females.

The relationship between plasma steroid hormone concentrations and the reproductive cycle in the Northern Pacific rattlesnake, Crotalus oreganus

We describe the reproductive cycle of Northern Pacific rattlesnakes ( Crotalus oreganus) by quantifying steroid hormone concentrations and observing reproductive behaviors in free-ranging individuals. Additionally, we examined reproductive tissues from museum specimens. Plasma steroid hormone concentrations were quantified for both male and female snakes throughout the active season (March–October). We measured testosterone (T), 5α-dihydrotestosterone (DHT), and corticosterone (B) concentrations in both sexes and 17β-estradiol (E2) and progesterone (P) in females only. We observed reproductive behaviors (e.g., consortship, courtship, and copulation) in the field and measured testis and follicle size in male and female snakes from museum collections to relate steroid hormone concentrations to the timing of reproductive events. Our study revealed that C. oreganus in central California exhibits a bimodal pattern of breeding, with most mating behavior occurring in the spring and some incidences of mating behavior observed in late summer/fall. Each breeding period corresponded with elevated androgen (T or DHT) levels in males. Testes were regressed in the spring when the majority of reproductive behavior was observed in this population, and they reached peak volume in August and September during spermatogenesis. Although we did not detect seasonal variation in female hormone concentrations, some females had high E2 in the spring and fall, coincident with mating and with increased follicle size (indicating vitellogenesis) in museum specimens. Females with high E2 concentrations also had high T and DHT concentrations. Corticosterone concentrations in males and females were not related either to time of year or to concentrations of any other hormones quantified. Progesterone concentrations in females also did not vary seasonally, but this likely reflected sampling bias as females tended to be underground, and thus unobtainable, in summer months when P would be expected to be elevated during gestation. In females, P was positively correlated with T and DHT, and E2 was positively correlated with T.

Plasma steroid concentrations in relation to reproductive performance in Thoroughbred stallions

Plasma steroid concentrations in relation to reproductive performance in Thoroughbred stallions

57 RELATIONSHIP BETWEEN FETAL ABNORMALITIES AND PERIPHERAL STEROID CONCENTRATIONS DURING GESTATION IN COWS TRANSFERRED WITH EMBRYOS PRODUCED BY SOMATIC CELL NUCLEAR TRANSFER

Cloning of mammals by nuclear transfer frequently results in gestational or neonatal failure with a variety of abnormalities that are likely caused by inappropriate epigenetic reprogramming. Early diagnosis of fetal abnormality is important for efficient production of cloned animals. Sex steroids are produced in the bovine placenta and their levels in the blood might be useful as a measure of fetal well-being, as in humans. The objective of this study was to investigate whether changes in peripheral levels of progesterone and estrogens reflect fetal abnormalities. Donor cells for nuclear transfer were obtained from subculture of cumulus cells retrieved from ovarian follicles of a Japanese Black cow. Recipient oocytes were derived from ovaries obtained at an abattoir and matured in vitro. Metaphase II oocytes were enucleated and each fused with a donor cell by DC pulses. Nuclear transferred oocytes were activated and cultured for 7 days. Embryos developed to the blastocyst stage were transferred into the uterine horn ipsilateral to the ovary bearing the CL of 32 multiparous Japanese Black and Holstein crossbred cows at 7 to 8 days after the day of standing estrus (Day 0). Blood was collected from Day 40 until parturition. Progesterone and estrogens in the blood plasma of 6 recipient cows with full-term delivery were measured by RIA. These profiles were compared with each other and with the changes in a cow made pregnant by MOET. Statistical differences were analyzed with repeated measures ANOVA. Parturition was induced on Day 290. Stillborn, dead, or euthanized calves were subjected to necropsy and histopathological analysis. Pregnant cows were 14, 13, and 9 on Days 30, 60, and 90, respectively. Thereafter, 3 aborted around Days 110, 120, and 190. Six cows delivered calves weighing 45.8 ± 2.1 kg (mean ± SEM) on Days 291 to 293. Their birth weights were greater than those of female calves (31.2 ± 0.4 kg, n = 6) produced by MOET in the same breed. Three calves grew normally until weaning. One was stillborn due to dystocia, but no abnormalities were observed except for large offspring syndrome. One was euthanized 2 days after natural delivery due to ananastasia. Thymic and thyroid hypoplasia, left ventricular dysplasia, and pulmonary fibrosis were found by necropsy. Another calf delivered by Caesarean section died of infirmity 2 days later and had thymic and thyroid hypoplasia. Changes in plasma steroid concentrations were consistent with each other and with those in a MOET cow except the last one, in which progesterone levels tended to be higher during the first trimester and estrogens were lower during the last half of gestation. Progesterone levels tended to be lower in cows bearing a healthy calf than in cows bearing a weak calf before parturition. These results imply that peripheral steroid levels may reflect fetal normality, although large offspring syndrome does not affect their concentrations.

Endocrine effects of the tapewormLigula intestinalisin its teleost host, the roach (Rutilus rutilus)

The effects of parasite infection by the cestode Ligula intestinalis on the reproductive function and endocrine system of wild roach Rutilus rutilus were evaluated. Gonad maturation, plasma vitellogenin, plasma steroid concentrations (i.e. progesterone, 11-keto-testosterone and 17-beta-estradiol) and brain aromatase activity were investigated in relation with parasitization. A low prevalence (8%) of ligulosed roach and a moderate impact of parasitization (mean parasitization index of 8.8%) were found in the studied population. Inhibition of gonad maturation generally resulted from infestation but 5% of the ligulosed roach nevertheless reached maturity. Main sex steroid plasma content was depleted in both genders. Male 11-keto-testosterone, female 17-beta-estradiol and progesterone plasma concentrations of both genders were, respectively, 27, 5 and 3 times lower in ligulosed fish when compared to their non-infected counterparts. Progesterone levels were negatively correlated with the parasitization index in females. Brain aromatase activity of infected roach was reduced to 50% of that of the non-infected fish. These results demonstrate significant negative effects on the reproductive function of wild roach infected by the tapeworm L. intestinalis collected from a site with low contamination.

Seasonal variations and alterations of sex steroid levels during the reproductive cycle of male roach ( Rutilus rutilus)

Seasonal variations of plasma steroid concentrations i.e. progesterone (P), 11-ketotestosterone (11-KT) and 17-β-estradiol (E2) were determined immunoenzymatically during a whole reproductive cycle in male roach ( Rutilus rutilus) caught in a reference site. Plasma 11-KT concentrations were significantly correlated with gonad growth, expressed as the gonado-somatic index ( R 2 = 0.60; p < 0.05) and highest concentrations (757 ± 99 pg ml −1) coincided with the final testis maturation in March. E2 and P concentrations peaked once during the reproductive cycle. E2 synthesis was significantly induced during the spawning period while P concentration peaked at the very start of the gametogenesis (June) thus suggesting specific roles of these steroids in the reproductive cycle. Comparison of reference levels were then made with plasma steroid concentrations from male roach sampled in polluted areas in the North of France. A significant decrease of E2 (50–60%) and 11-KT (76–84%) was measured, indicating that endocrine disrupting compounds may have interfered with the normal sex steroid synthesis. Contrary to the E2 and 11-KT sex steroids, plasma P concentration was not significantly affected in fish inhabiting impacted areas.

Consumption of animal products, their nutrient components and postmenopausal circulating steroid hormone concentrations

Little is known about nutritional factors that influence circulating concentrations of steroid hormones, which are consistently associated with risk of breast cancer for postmenopausal women. We aimed to investigate the association between consumption of animal products and the plasma concentrations of steroid hormones and sex hormone-binding globulin (SHBG). Cross-sectional analysis was conducted on plasma from 766 naturally postmenopausal women. We measured plasma concentrations of steroid hormones and SHBG, and estimated dietary intakes using a 121-item food frequency questionnaire. Log-transformed values of hormone concentrations were regressed on quartiles of intake of meat and dairy products among food items, and fats, proteins and cholesterol among nutrient intake. Total red and fresh red meat consumption was negatively associated with SHBG levels (P for trend=0.04 and <0.01, respectively). Mean SHBG concentrations were approximately 8% and 13% lower for women in the highest quartile compared with the lowest quartile of total red and fresh red meat consumption, respectively. Positive associations were observed between dairy product consumption and total and free estradiol concentrations (P for trend=0.02 and 0.03, respectively). Mean concentrations of total and free estradiol were 15 and 14% higher for women in the highest quartile of dairy product consumption than for those in the lowest quartile, respectively. No associations were observed with consumption of processed meat, chicken, fish, eggs, cholesterol, fats or protein. Our study suggests that greater consumption of total red and fresh red meat and dairy products might influence circulating concentrations of SHBG and estradiol, respectively. Confirmation and further investigation is required.

Plasma sex hormone concentrations and breast cancer risk in an ethnically diverse population of postmenopausal women: the Multiethnic Cohort Study

To add to the existing evidence that comes mostly from White populations, we conducted a nested case-control study to examine the association between sex hormones and breast cancer risk within the Multiethnic Cohort that includes Japanese American, White, Native Hawaiian, African American, and Latina women. Of the postmenopausal women for whom we had a plasma sample, 132 developed breast cancer during follow-up. Two controls per case, matched on study area (Hawaii, Los Angeles), ethnicity/race, birth year, date and time of blood draw and time fasting, were randomly selected from the women who had not developed breast cancer. Levels of estradiol (E(2)), estrone (E(1)), androstenedione, dehydroepiandrosterone (DHEA), and testosterone were quantified by RIA after organic extraction and Celite column partition chromatography. E(1) sulfate, DHEA sulfate (DHEAS), and sex hormone-binding globulin (SHBG) were quantified by direct immunoassays. Based on conditional logistic regression, the sex hormones were positively associated and SHBG was negatively associated with breast cancer risk. All associations, except those with DHEAS and testosterone showed a significant linear trend. The odds ratio (OR) associated with a doubling of E(2) levels was 2.26 (95% confidence interval (CI) 1.58-3.25), and the OR associated with a doubling of testosterone levels was 1.34 (95% CI 0.98-1.82). The associations in Japanese American women, who constituted 54% of our sample, were similar to or nonsignificantly stronger than in the overall group. This study provides the best evidence to date that the association between sex hormones and breast cancer risk is generalizable to an ethnically diverse population.

Controlled Steroid Delivery via Bioabsorbable Stent: Safety and Performance in a Rabbit Model

Middle turbinate lateralization, adhesions, and inflammation are causes of suboptimal sinus patency following surgery. A bioabsorbable drug-eluting stent has been developed to maintain sinus patency while providing controlled steroid delivery to the sinus mucosa. The aim of this study was to characterize the in vivo drug delivery efficacy and tolerance of this stent in a rabbit model. Bioabsorbable stents coated with mometasone furoate were placed bilaterally in the maxillary sinuses of 31 rabbits via dorsal maxillary sinusotomy. Animals were sacrificed between 5 days and 18 weeks postoperatively. Efficacy was assessed by measuring tissue concentrations of steroid in maxillary sinus and nasal mucosa and by measurement of plasma steroid concentrations. Tolerance was assessed by histological evaluation of the sinus mucosa at different time points. Therapeutic mucosal drug concentrations were attained in a time-dependent fashion (range 175-28,189 ng/g). Plasma drug concentrations were generally near or below the lower limit of quantification (15 pg/mL). Histopathological examination of the mucosa showed no differences in the reaction to steroid-coated stents versus nondrug-coated control stents, with inflammation, epithelial ulceration, and bony reaction ranging from none to mild at all time points. Microscopic fungal hyphae were noted in a small proportion of both treatment and control sinuses, without evidence of associated adverse tissue reaction. In a rabbit model, mometasone-coated bioabsorbable stents are able to provide local steroid delivery with negligible systemic absorption. Corticosteroid-eluting stents may prove useful following endoscopic sinus surgery in maintaining sinus patency and reducing inflammation.

I. Effects of a dopamine receptor antagonist on fathead minnow, Pimephales promelas, reproduction

Neurotransmitters such as dopamine play an important role in regulating fish reproduction. However, the potential for neuroendocrine active chemicals to disrupt fish reproduction has not been well studied, despite emerging evidence of their discharge into aquatic environments. This study is the first to apply the fathead minnow 21 d reproduction assay developed for the US Endocrine Disruptor Screening Program to evaluate the reproductive toxicity of a model neuroendocrine active chemical, the dopamine 2 receptor antagonist, haloperidol. Continuous exposure to up to 20 μg haloperidol/L had no significant effects on fathead minnow fecundity, secondary sex characteristics, gonad histology, or plasma steroid and vitellogenin concentrations. The only significant effect observed was an increase in gonadotropin-releasing hormone (cGnRH) transcripts in the male brain. Results suggest that non-lethal concentrations of haloperidol do not directly impair fish reproduction. Potential effects of haloperidol on reproductive behaviors and gene expression were examined in a companion study.

Relationship between caffeine intake and plasma sex hormone concentrations in premenopausal and postmenopausal women

Circulating estrogens and androgens are important factors in the development of various female cancers. Caffeine intake may decrease risk of breast and ovarian cancer, although the data are not entirely consistent. Whether or not caffeine affects cancer risk by altering sex hormone levels is currently unknown. We examined the relationship of caffeine, coffee, decaffeinated coffee, and tea with plasma concentrations of estrogens, androgens, progesterone, prolactin, and sex hormone-binding globulin (SHBG) in 524 premenopausal and 713 postmenopausal women from the Nurses' Health Study (NHS) and NHSII. In premenopausal women, caffeine intake was inversely associated with luteal total and free estradiol, and positively associated with luteal progesterone levels (P-trend = .02, .01, .03, respectively). Coffee intake was significantly associated with lower luteal total and free estradiol levels, but not luteal progesterone levels (P-trend = .007, .004, .20, respectively). Among the postmenopausal women, there was a positive association between caffeine and coffee intake and SHBG levels (P-trend = .03 and .06, respectively). No significant associations were detected with the other hormones. Data from this cross-sectional study suggest that caffeine may alter circulating levels of luteal estrogens and SHBG, representing possible mechanisms by which coffee or caffeine may be associated with pre- and postmenopausal malignancies, respectively. Future studies evaluating how caffeine-mediated alterations in sex hormones and binding protein levels affect the risk of female cancers are warranted.

Human sex hormone-binding globulin gene expression- multiple promoters and complex alternative splicing.

BackgroundHuman sex hormone-binding globulin (SHBG) regulates free sex steroid concentrations in plasma and modulates rapid, membrane based steroid signaling. SHBG is encoded by an eight exon-long transcript whose expression is regulated by a downstream promoter (PL). The SHBG gene was previously shown to express a second major transcript of unknown function, derived from an upstream promoter (PT), and two minor transcripts.ResultsWe report that transcriptional expression of the human SHBG gene is far more complex than previously described. PL and PT direct the expression of at least six independent transcripts each, resulting from alternative splicing of exons 4, 5, 6, and/or 7. We mapped two transcriptional start sites downstream of PL and PT, and present evidence for a third SHBG gene promoter (PN) within the neighboring FXR2 gene; PN regulates the expression of at least seven independent SHBG gene transcripts, each possessing a novel, 164-nt first exon (1N). Transcriptional expression patterns were generated for human prostate, breast, testis, liver, and brain, and the LNCaP, MCF-7, and HepG2 cell lines. Each expresses the SHBG transcript, albeit in varying abundance. Alternative splicing was more pronounced in the cancer cell lines. PL- PT- and PN-derived transcripts were most abundant in liver, testis, and prostate, respectively. Initial findings reveal the existence of a smaller immunoreactive SHBG species in LNCaP, MCF-7, and HepG2 cells.ConclusionThese results extend our understanding of human SHBG gene transcription, and raise new and important questions regarding the role of novel alternatively spliced transcripts, their function in hormonally responsive tissues including the breast and prostate, and the role that aberrant SHBG gene expression may play in cancer.

A Computational Model of the Hypothalamic-Pituitary-Gonadal Axis in Male Fathead Minnows Exposed to 17α-Ethinylestradiol and 17β-Estradiol

Estrogenic chemicals in the aquatic environment have been shown to cause a variety of reproductive anomalies in fish including full sex reversal, intersex, and altered population sex ratios. Two estrogens found in the aquatic environment, 17alpha-ethinylestradiol (EE(2)) and 17beta-estradiol (E(2)), have been measured in wastewater treatment effluents and have been shown to cause adverse effects in fish. To further our understanding of how estrogen exposure affects reproductive endpoints in the male fathead minnow (FHM, Pimephales promelas), a physiologically based computational model was developed of the hypothalamic-pituitary-gonadal (HPG) axis. Apical reproductive endpoints in the model include plasma steroid hormone and vitellogenin concentrations. Using Markov chain Monte Carlo simulation, the model was calibrated with data from unexposed FHM, and FHM exposed to EE(2) and E(2). Independent experimental data sets were used to evaluate model predictions. We found good agreement between our model predictions and a variety of measured reproductive endpoints, although the model underpredicts unexposed FHM reproductive endpoint variances, and overpredicts variances in estrogen-exposed FHM. We conclude that this model provides a robust representation of the HPG axis in male FHM.

The Treatment of Adrenal Cortical Disease in Ferrets with 4.7-mg Deslorelin Acetate Implants

Thirty pet ferrets with adrenocortical disease (ACD) of varying severity and duration were evaluated for response to a single administration of a slow release 4.7 mg deslorelin acetate implant. Clinical response to deslorelin was monitored via a physical examination performed every 3 to 4 months. Adrenal ultrasound measurements were taken every 3-4 months until clinical relapse. At clinical relapse, duration of symptom suppression and adrenal size and growth were determined. Administration of a single 4.7 mg implant of deslorelin acetate resulted in significant decreases in the clinical signs and hormonal concentrations associated with ACD. Within 14 days post-implant, vulvar swelling, pruritus, sexual behaviors and aggression decreased or disappeared. Hair re-growth was evident by 4-6 weeks post implant. Within two months post deslorelin implant, plasma concentrations of steroid hormones decreased: mean estradiol concentration decreased 28%; 17-hydroxyprogesterone levels decreased 89% and androstenedione levels decreased 88%. The response to a single 4.7 mg implant of deslorelin acetate was transitory. The mean ± SD time to recurrence of clinical signs was 17.6 ± 5.0 months (range, 8.0-30.0 months). Repeated ultrasound measurements revealed no statistical difference in size of the adrenals (right or left) before, during the months of deslorelin implant and at clinical relapse. Slow release 4.7 mg deslorelin implants can effectively be used to temporarily eliminate the clinical signs and reduce steroid hormone concentrations in ferrets with ACD. This dose of deslorelin does appear to influence adrenal tumor growth causing a decrease in adrenal size in some ferrets, and mild enlargement of adrenal glands in most ferrets with 2 of 30 implanted animals developing large tumors before clinical relapse. The long-term effect of treatment with deslorelin on adrenal tumor pathology requires additional investigation. At this time, surgical removal of the adrenal tumor remains the only curative treatment; however, 4.7 mg deslorelin implants are useful in the long-term management of ACD hormone-induced sequelae and may be as effective assurgical management.

Transgenerational marking of marine fish larvae: stable‐isotope retention, physiological effects and health issues

This study examined the toxicological and physiological responses of a commercially important coral-reef grouper, Plectropomus leopardus (Serranidae), to injection of enriched stable-isotope barium chloride (BaCl(2)) solution. Thirty adult P. leopardus were subject to one of two (138)BaCl(2) injection treatment groups (corresponding to dosage rates of 2 and 4 mg (138)Ba kg(-1) body mass), and a control group in which fish were injected with 0.9% sodium chloride (NaCl) solution. Fish from each group were sampled at post-injection intervals of 48 h and 1, 3, 5 and 8 weeks, at which time blood and tissue samples were removed from each fish. Residual concentrations of Ba and (138)Ba:(137)Ba ratios were measured in muscle, gonad, liver and bone tissues of each experimental fish. Elevated Ba concentrations were detected in all treatment fish tissue samples within 48 h post injection. Residual Ba concentrations decreased throughout the remainder of the 8 week experimental period in all tissues except bone. The BaCl(2) injection had no significant effects on measured whole blood variables or on the plasma concentrations of steroid hormones. Enriched Ba stable isotopes can therefore be used at low dosages to mark larvae of commercially important marine fishes, without adverse effects on the health of the fishes or on humans who may consume them.

Exposure to pheromones increases plasma corticosterone concentrations in a terrestrial salamander

Sensory cues involved in social interactions can influence plasma steroid hormone concentrations. Although pheromonal communication is common in amphibians, it is unknown whether pheromones can alter hormone levels in amphibians as they do in mammals. We tested whether courtship pheromones would alter steroid hormone concentrations in male and female terrestrial salamanders ( Plethodon shermani). Plasma corticosterone concentrations were elevated in male salamanders exposed to mental gland courtship pheromones, as compared to males exposed to female skin secretions or a saline control. Chemosensory cues had no effect on testosterone levels in males or on corticosterone or estradiol levels in females. These results provide the first evidence that pheromones have priming effects on the endocrine system in amphibians.

Ovarian follicular dynamics and plasma steroid concentrations are not significantly different in ewes given intravaginal sponges containing either 20 or 40 mg of fluorogestone acetate

Although various progestagens are often used to induce and synchronize estrus and ovulation in ruminants, concerns regarding residues are the impetus to develop alternative approaches, including reduced doses of progestagens. Therefore, the objective was to determine whether ovarian function was affected by halving the dose of fluorogestone acetate in intravaginal sponges for synchronizing ovulation in sheep during the physiologic breeding season. Twenty Manchega ewes, 4–6-year-old, were randomly allocated to receive an intravaginal sponge containing either 20 mg (P20, n = 10) or 40 mg of fluorogestone acetate (P40, n = 10). Cloprostenol (125 μg) was given at sponge insertion, and all sponges were removed after 6 d. Ovarian follicular dynamics (monitored by daily ultrasonography) and other aspects of ovarian function did not differ significantly between the two groups. Ovulatory follicles (OF) grew at a similar growth rate ( r = 0.62; P < 0.001), with comparable initial and maximum diameters (4.2 ± 0.4 to 6.0 ± 0.3 mm in P20 vs. 4.6 ± 0.6 to 5.7 ± 0.2 mm in P40, mean ± S.E.M.). Plasma estradiol concentrations (determined once daily) increased linearly during the 72 h interval after sponge removal (1.3 ± 0.1 to 3.3 ± 0.1 pg/mL for P20, P < 0.005 and 1.4 ± 0.1 to 3.1 ± 0.2 pg/mL for P40, P < 0.005). Ten days after sponge removal, ovulation rates (1.2 ± 0.2 for P20 and 1.4 ± 0.3 for P40), and plasma progesterone concentrations (3.8 ± 0.35 ng/mL for P20 and 3.9 ± 0.38 ng/mL for P40) were similar. In conclusion, reducing the dose of fluorogestone acetate from 40 to 20 mg did not affect significantly ovarian follicular dynamics or other aspects of ovarian function.

Pattern of Sex Steroid Concentrations in Relation to the Annual Reproductive Cycle of Wild and Captive Black Rockfish

AbstractGonadal development and plasma steroid hormone concentrations of wild (N = 73) and captive (N = 65) black rockfish Sebastes melanops were examined over 1 year. Seasonal variation was observed in the concentrations of testosterone and estradiol in the plasma of wild female black rockfish, the highest concentrations of each occurring in October. Male black rockfish exhibited the highest testosterone concentrations during the summer (July 29–August 9). Gonadosomatic index (GSI) and estradiol concentration were highly correlated for wild female black rockfish sampled in the fall, demonstrating the utility of this nonlethal approach for evaluating gonadal status during this species' vitellogenic period. No relationship between testosterone concentrations and GSI was observed in male fish. Hormone concentrations in captive female black rockfish were depressed throughout the year, illustrating that maintenance conditions were not conducive to the normal progression of reproductive events for this species.

Non-lethal assessment of reproductive characteristics for management and conservation of sharks

Chondrichthyans are one of the most vulnerable groups of marine species, with increasing numbers being listed as endangered or threatened. Fundamental to the conservation and management of any animal is an understanding of their reproduction and particularly, the size at which individuals enter the reproductive population. Size at maturity in sharks is typically obtained by macroscopic examination of the gonads after sacrificing the fish. Using the draughtboard shark Cephaloscyllium laticeps as a case study, we found that equivalent information can be obtained nondestructively using steroid hormone levels measured from a blood sample. This technique allowed us to release the shark after only 1 to 2 min of handling. A combination of plasma steroid hormone concentrations and an external measurement (total length for females and clasper length for males) was used to determine that over 90% of female and 95% of male sharks were either juveniles or adults. The estimates of size at maturity from the hormone analysis were within 3% of equivalent values of dissected sharks. Once validated, hormone levels can also be used to determine seasonal reproductive patterns for the adult population. Our results demonstrated how measurement of plasma levels of steroid hormones can provide a non-destructive method for obtaining reproductive data necessary for managing vulnerable and endangered shark species. The development of a non-destructive sampling tool also allows for improved ethical investigation into this vulnerable group of marine fishes.