The gut microbiota-bile acid axis mediates the beneficial associations between plasma vitamin D and metabolic syndrome in Chinese adults: A prospective study

BACKGROUND & AIMS

Previous studies have suggested that circulating 25-hydroxyvitamin D (25 [OH]D, VD) and the gut microbiota-bile acid axis play crucial roles in metabolic health. Exploring the mediating role of the gut microbiota-bile acid axis would improve our understanding of the mechanisms underlying the effects of VD on human metabolic health. This study examined the association between plasma 25(OH)D and the prevalence/incidence of metabolic syndrome (MetS) and the mediating role of the gut microbiota-bile acid axis.

METHODS

This prospective study included 3180 participants with plasma 25(OH)D data at baseline and 2966 participants with a 9-year follow-up. MetS was determined every three years. The gut microbiota was analyzed by 16S rRNA sequencing in 1752 participants, and targeted bile acid metabolites in feces were further determined in 974 participants using UPLC‒MS/MS at the middle of the study. Mediating roles of microbiota and bile acids in the VD-MetS associations were analyzed using mediation/path analyses adjusted for potential confounders.

RESULTS

Among the 2966 participants who were followed-up, 1520, 193, 647, and 606 were MetS-free (normal), recovered, had incident MetS, and had persistent MetS, respectively. The multivariable-adjusted ORs (95% CIs) of MetS prevalence were 0.65 (0.50, 0.84) for baseline MetS and 0.46 (0.33, 0.65) for 9-year persistent MetS in quartile 4 (compared to quartile 1) of plasma 25(OH)D (median: 37.7 vs. 19.6, ng/ml). The corresponding HR (95% CI) of 9-year MetS incidence was 0.71 (0.56, 0.90) (all P-trend < 0.05). Higher VD concentrations were associated with greater α-diversity of the gut microbiota, which was inversely correlated with MetS risk. The groups classified by VD and MetS status had significantly different β-diversity. Ruminiclostridium-6 and Christensenellaceae R-7 group were enriched in the high-VD group and were inversely associated with MetS. However, opposite associations were observed for Lachnoclostridium and Acidaminococcus. The overlapping differential microbial score (ODMS) developed from the four differential genera explained 12.2% of the VD-MetS associations (P_mediation = 0.015). Furthermore, the fecal bile acid score created from 11 differential bile acids related to ODMS and MetS mediated 34.2% of the association between ODMS and MetS (P_mediation = 0.029). Path analyses showed that the inverse association between plasma 25(OH)D and MetS could be mediated by the gut microbiota-bile acid axis.

CONCLUSIONS

The findings suggest that the gut microbiota-bile acid axis partially mediates the beneficial association between plasma 25(OH)D and the risk of persistent MetS and incident MetS in the Chinese population.

Higher serum vitamin A is associated with a worsened progression of non-alcoholic fatty liver disease in adults: a prospective study

Background: The association between serum vitamin A and non-alcoholic fatty liver disease (NAFLD) remains uncertain due to inconsistent results and scarce longitudinal data. We examined the prospective associations between serum vitamin A and the evolution of the NAFLD severity score as well as the potential mediating effects in middle-aged and older Chinese adults. Method: A total of 2658 adults (between 40-75 years of age) were included in the analysis. We determined the serum concentrations of vitamin A at the onset of the study (the baseline), and the degree of NAFLD after years 3 and 6. Results: Subjects were classified into stable, progressed, and improved groups according to the changes in their severity score (0-3) of NAFLD between two visits. Analyses of covariance showed that the serum VA concentrations were positively associated with NAFLD progression (all p-trend < 0.05). After adjusting for potential confounders, the mean differences in the serum vitamin A were 7.7% lower in the improved group than those in the progressed group among the total population. Path analyses showed that vitamin A was positively associated with the serum retinol-binding protein 4, triglycerides, insulin resistance, and body mass index (standardized β 0.065-0.304, all p < 0.001), and all of these factors positively correlated with the prevalence and progression of NAFLD (standardized β 0.045-0.384, all p < 0.01). Conclusions: A higher serum vitamin A concentration was associated with NAFLD progression, which might be mediated by increases in the serum retinol-binding protein 4, triglycerides, insulin resistance, and body mass index.

[Clinical and pathological features and mutational types of WT1 mutation-associated nephropathy]

Objective: To explore the clinical and pathological features and mutational types and their relations with WT1 mutation-associated nephropathy (WT1MAN). Methods: The clinical and pathological data and the results of WT1 mutation analysis of the cases from Nanfang Hospital of Southern Medical University, Sun Yat-sen Memorial Hospital and The First Affiliated Hospital of Sun Yat-sen University whom we recruited recently and reported during the last ten years were analyzed. Results: Totally, 20 cases (6 males and 14 females), included 5 newly diagnosed cases, were recruited. (1) Ten children were diagnosed with Denys-Drash syndrome (DDS): The median onset age of proteinuria was 1 year and 7 months. Diffuse mesangial sclerosis (DMS) were revealed in 3 cases, minimal lesions (MCD) in 4 cases, and focal segmental glomerulosclerosis (FSGS) in 1 case; renal pathology was not available in the other 2 cases. Glomerular basement membrane (GBM) thickening was observed in 2 cases. Calcineurin inhibitors (CNIs) were administered in 5 cases, complete remission of proteinuria was observed in 3 cases, partial remission in the other 2 cases. Genetic analysis revealed that six cases had WT1 missense mutation, 3 had nonsense mutation, and 1 had frameshift mutation. (2) Two cases were diagnosed with Frasier syndrome (FS): proteinuria was observed at 1 year and 1 month of age and 1 year and 9 months of age, respectively. FSGS with GBM layering were observed in both cases. They progressed to ESRD at 1 year and 6 months of age and 6 years and 6 months of age, respectively. CNI was tried in 1 case with partial proteinuria remission. Both patients were detected to have WT1 splice mutation. (3) Isolated nephropathy (IN) was observed in 8 cases: three had splice mutation, 5 had missense mutation. Of the 3 patients with splice mutation, one was found to have nephropathy and renal failure at the age of 5 months. The other two cases (1 was FSGS and another MCD), both had GBM layering. CNIs were tried on both of them, one got partial remission with normal renal function at the age of fourteen years, the other one had no response and entered ESRD at the age of 6 years and 9 months. Of the 5 cases with missense mutation, 3 had DMS, 2 of them entered ESRD within 6 months of age, another case had DMS entered ESRD at 9 years of age. One case with FSGS, was treated with CNIs and got complete remission. Conclusions: Slow progression (7/10) nephropathy was observed in DDS patients. Missense mutation (11/20) was the most common type of WT1 variants, followed by splice mutation (5/20) in this group of patients. Early onset nephropathy (4/5), rapid progression (4/5) and GBM layering (4/4) wereobserved in patients with splice mutation. CNI was effective in reducing or even eliminating proteinuria in WT1 MAN patients (8/9).

[Clinical features and gene mutation analysis of 13 Chinese juvenile patients with nephronophthisis]

Objective: To explore the clinical features and pathogenic gene mutation of juvenile nephronophthisis (NPHP) in Chinese patients. Method: Clinical data and blood samples of 27 juvenile NPHP patients from 25 families who were initially clinically diagnosed in six hospitals in Guangdong province were collected. NPHP1 homozygous deletions were detected in all patients. Sequencing of NPHP1 gene was performed when homozygous deletions were not found in patients without eye involvement. In patients with eye involvement, NPHP5 sequencing was carried out initially and subsequently NPHP10 gene and NPHP1 when there were no NPHP5 gene mutation found. Result: Diagnosis was confirmed in 13 patients by renal pathology and (or) gene sequencing, including four boys and nine girls with a median onset age of 8.5(0.1-12.8) years. Seven of the 13 patients had a normal routine urine test and six patients had mild to moderate proteinuria. None had persistent hematuria. The estimated glomerular filtration rate of the 13 patients was (12.7±10.7) ml/(min·1.73 m²) at the time of diagnosis. Renal cysts were found in only five patients by iconography. Decreased renal size was observed in nine cases and normal renal size in four patients. Renal pathology was available in five patients, renal cysts formation at the cortical-medullar area, thickening and laying tubular basement membrane, were observed. Two of the thirteen children had eye involvement, one had liver impairment and one had growth retardation. NPHP1 gene defects were detected in seven patients with a mutation rate of 25.9%, and large homozygous deletions were observed in three patients. Four patients had single point mutations, i. e. compound heterozygous mutations (c.13 C>T and c. 1520+ 5 G>A) in one patient; homozygous mutation in three patients, two patients were siblings from the same pedigree harbored c. 1756 C>T and the other one harbored c. 1298delA. NPHP5 gene homozygous mutation was found in one pedigree. The fourteen children without renal pathology and whose genetic tests were negative shared similar clinical features with the thirteen patients whose diagnosis were confirmed by gene mutation and (or) renal pathology. Conclusion: The onset of juvenile NPHP is insidious. Urine and renal iconography changes are mild or negative. The ratio of NPHP1 mutant patient is similar with previous reports, but the proportion of NPHP1 gene homozygous deletions is much lower and all of the NPHP1 gene single point mutations detected in this research were novel, which indicates a genetic discrepancy existed between Chinese NPHP patients and the western ones.

Divergence and polymorphism analysis of IGF1Ra and IGF1Rb from orange-spotted grouper, Epinephelus coioides (Hamilton)

Orange-spotted grouper (Epinephelus coioides) is one of the most important marine fish and has a high market value. The insulin-like growth factor type 1 receptor (IGF1R) is a component of the insulin-like growth factor signaling system, and demonstrates important roles during growth. Based on information from livestock, we used IGF1R as a candidate gene to survey single nucleotide polymorphisms. In the present study, the sequences of IGF1Ra and IGF1Rb from orange-spotted grouper were obtained from the genome sequences and their clustering in clades a and b, respectively, was confirmed by phylogenetic analysis. Fourteen critical amino acids underlying functional divergence were detected between the two clades, revealing the molecular basis of their functional differences. Nearly one-fourth (22 kbp) of the genomic sequence of IGF1Ra was sequenced in a mass cross population, and nucleotide diversity and linkage disequilibrium levels were investigated. Nucleotide diversity was 0.00328 for π and 0.00344 for θ_w. The half decay of the squared allele-frequency correlation was 10,835 base pairs. Comparatively, the relatively high level of linkage and the significant deviation from neutrality-based codons in IGR1R showed that this gene was under selection. A site (KR269824.1:g. 63762C>T), located in the sixth intron, was significantly associated with eyeball diameter (P = 1.39 x 10^-4, Q-value: 2.33 x 10^-2), which accounted for 11.1% of phenotypic variance. These results highlight the important function of IGF1R in orange-spotted grouper and may be beneficial in the breeding of this species.

Isolation and characterization of novel polymorphic microsatellite markers for Epinephelus akaara

In the present study, ten novel microsatellite markers were developed from an enriched-(CA)13 genomic library of Epinephelus akaara. The mean number of alleles per locus was 21.6, with a range of 12 to 33. Observed heterozygosity ranged from 0.767 to 0.967, and expected heterozygosity ranged from 0.831 to 0.975, with mean values of 0.877 and 0.923, respectively. Among the ten loci, three loci deviated from Hardy-Weinberg equilibrium after sequential Bonferroni's correction. These polymorphic microsatellite markers may be useful for studies on the population genetics of E. akaara.

Nineteen polymorphic microsatellite markers developed for Trachinotus ovatus

To evaluate the population genetic diversity of the ovate pompano, we isolated and characterized 19 microsatellite markers using a (CA)13-enriched genomic library. Polymorphism was assessed in 30 individuals from a single population collected from the Daya Bay Aquaculture Center, Guangdong, China. The number of alleles per locus ranged from 2 to 18 with an average of 7.8. The observed and expected heterozygosities varied from 0.2667 to 1.000 and from 0.3960 to 0.9435, respectively. Sixteen of 19 loci conformed to Hardy-Weinberg equilibrium, and no significant linkage disequilibrium was detected between any locus pairs. Our study supplies candidate microsatellite markers that can be useful for studying the population genetic structure of ovate pompano.

Soluble interleukin-1 receptor, a potential negative regulator of orange-spotted grouper Epinephelus coioides interleukin-1 system

In this study, the cDNA sequence encoding interleukin-1 (Il-1) receptor-like protein of orange-spotted grouper Epinephelus coioides was obtained. The newly identified sequence was named soluble type I Il-1 receptor (sIl-1rI) owing to its structural composition, which had two Ig-like domains, lack of transmembrane region and the Toll/interleukin-1 receptor (TIR) domain, similar to the brown rat Rattus norvegicus soluble Il-1rI. In addition, sequence comparison and phylogenetic analysis indicated that E. coioides sequence had a closer relationship with Il-1rI than Il-1rII. Real-time PCR revealed that sil-1rI mRNA expression presented a process of decrease, restoration and increase in Cryptocaryon irritans-infected E. coioides. The negative correlation between Il-1β and sil-1rI mRNA in C. irritans-infected head-kidney implied the potential negative regulatory role of sil-1rI in E. coioides Il-1 system. The leucocytes incubated with lipopolysaccharide or polyriboinosinic polyribocytidylic acid exhibited different expression profiles of sil-1rI. Recombinant Il-1β (rIl-1β) protein was capable of inducing sil-1rI mRNA under the concentration of 100 ng ml(-1) , suggesting that high dosage or excess Il-1β would stimulate the expression of sil-1rI to maintain the homoeostasis of E. coioides Il-1 system. For the first time, the role of teleost Il-1rI in parasite infection has been identified, and soluble Il-1r was found in fish.

Identification and expression analysis of major histocompatibility complex IIB gene in orange-spotted grouper Epinephelus coioides

In this study, complementary DNA (cDNA) and DNA sequences of major histocompatibility complex (MHC) class IIB genes (mhcIIB) were cloned from orange-spotted grouper Epinephelus coioides. The gene structure of E. coioides mhcIIB consists of five exons and four introns, and its deduced amino acid sequence length is 249 amino acids, including a signal peptide, a peptide-binding region, an IGC1 domain, a transmembrane region and a cytoplasmic tail. A phylogenetic study showed that E. coioides mhcIIB shared 32.0-79.1% identity with those of other teleosts and mammals. Real-time reverse transcriptase (RT)-PCR was performed to detect the class IIB gene expression in eight different tissues. To characterize the relationship between E. coioides mhcIIB gene and pathogens, in vivo and in vitro studies were performed. Challenge of Cryptocaryon irritans revealed that class IIB genes were down-regulated after 24 and 48 h of challenge, and their expression was later restored at 72 h. Stimulation of isolated E. coioides leukocytes with lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid (PolyI:C) significantly increased peripheral blood and spleen mhcIIB expression, while head kidney mhcIIB expression remained constant.

Development and characterization of 32 microsatellite loci in the giant grouper Epinephelus lanceolatus (Serranidae)

An economically important marine fish species, the giant grouper Epinephelus lanceolatus (Serranidae) is widely cultured in Taiwan and costal areas of China. We isolated and characterized 32 polymorphic microsatellite loci from a CA-enriched genomic library of giant grouper. The number of alleles per locus ranged from 3 to 7, with a mean of 4.69. Observed and expected heterozygosities per locus varied from 0.387 to 1.000 and from 0.377 to 0.843, respectively. Six loci significantly deviated from Hardy-Weinberg equilibrium. After sequential Bonferroni's correction, only two loci showed deviation from Hardy-Weinberg equilibrium, and no linkage disequilibrium was found between any pair of loci. These microsatellites can be useful tools for the study of population genetics in the giant grouper.

Effects of food deprivation on expression of growth hormone receptor and proximate composition in liver of black seabream Acanthopagrus schlegeli

The effects of food deprivation on the hepatic level growth hormone receptor (GHR) were investigated in black seabream (Acanthopagrus schlegeli) both at the protein level (by radioreceptor assay) and at the mRNA level (by ribonuclease protection assay). Serum levels of growth hormone (GH) and triiodothyronine (T(3)) were also measured. Condition factor and hepatic proximate composition of the fish were also assessed. Significant decrease in hepatic GHR binding was recorded as early as on day 2 of starvation. On day 30 this decrease was even more pronounced, with the level in the starved fish reaching less than 20% the fed control level. A concomitant decrease in the hepatic GHR mRNA content was also noted during this period, with a progressive decrease from day 2 to day 30 of starvation. The extent of decrease in the mRNA content was less pronounced than the decrease in receptor binding, with the hepatic GHR mRNA content in the day 30 starved fish representing approximately 30% of the level in the fed control. In large contrast, serum GH level increased progressively during starvation. After 30 days of starvation, serum GH levels in the starved fish were more than three times the concentration found in the fed control. Serum T(3) levels, on the other hand, decreased during starvation, with the difference reaching significance on day 15 and day 30. After 30 days of starvation, serum T(3) levels in the starved fish were only approximately 40% the concentration found in the fed control. The hepatic lipid content exhibited an increasing trend during starvation. On day 30 the hepatic lipid content of the starved fish had doubled the level found in the fed control. However, the hepatic protein content did not exhibit much change during starvation. There was also a minor decrease in the moisture content of the liver during starvation, but the condition factor of the fish as a whole registered a gradual decrease during the course of food deprivation.

Seabream growth hormone receptor: molecular cloning and functional studies of the full-length cDNA, and tissue expression of two alternatively spliced forms

A full-length clone of the growth hormone receptor (GHR) was isolated from a cDNA library constructed from the liver of black seabream (Acanthopagrus schlegeli). The seabream GHR (sbGHR) cDNA sequence encodes a transmembrane protein of 640 amino acids (aa) possessing the characteristic motifs and architectural design of GHRs of other species. When compared to the other fish GHRs, it is most homologous to another marine fish species, the turbot, where the aa identity is 79.3%. But the sbGHR sequence is more remotely related to the goldfish GHR (51.6% aa identity) and the salmonid GHRs (approximately 46-48% aa identities). Phylogenetic comparison with other known GHRs indicates that the fish GHRs constitute a distinct group among the different vertebrate classes. The aa identities between sbGHR and other GHRs are low, being around 40% with mammalian GHRs, around 45% with avian and reptilian GHRs, and less than 35% with Xenopus GHR. CHO cells transfected with the sbGHR cDNA can be stimulated to proliferate by recombinant seabream growth hormone (sbGH). In addition, the transfected cells can transactivate a co-expressed mammalian serine protease inhibitor (Spi) 2.1 promoter upon stimulation by sbGH. These functional assays indicated that the fish receptor can interact with its homologous ligand to evoke the downstream post-receptor events. Reverse transcription-polymerase chain reaction (RT-PCR) and genomic PCR using a pair of gene-specific primers revealed the expression of two alternatively spliced forms of sbGHR in various tissues of the fish. A 93-bp intron, unique to the sbGHR gene and not found in any other known GHR genes, is alternatively spliced to give rise to two forms of receptor mRNA transcripts. The two forms of the receptor are differentially expressed among the different tissues of the fish.

Beam hardening correction for computed tomography images using a postreconstruction method and equivalent tissue concept

A postreconstruction method for correcting the beam-hardening artifacts in computed tomography (CT) images is proposed. This method does not require x-ray spectrum measurement. The authors assumed that a pixel in a CT image can be decomposed into equivalent tissue percentages, depending on its CT number. A scout view of the step wedges made of these equivalent tissues was performed to obtain a beam-hardening correction curve for each tissue. Projecting through the CT image from various angles generated simulated projection data and the total thickness of each tissue along the ray. The correction term was estimated using the tissue thickness traveled by the ray, and this term was then added to its corresponding projection data. A second reconstruction using the corrected projection data yielded a beam-hardening corrected image. The preliminary results show that this method reduces beam hardening artifacts by 14% for aluminum and increased the object contrast by 18% near the aluminum-water boundary. The variation in CT numbers at different locations were reduced, and the aluminum CT number also was restored.

Pituitary adenylate cyclase activating polypeptide as a novel hypophysiotropic factor in fish

Pituitary adenylate cyclase activating polypeptide (PACAP) is a novel member of the secretin-glucagon peptide family. In mammals, this peptide has been located in a wide range of tissues and is involved in a variety of biological functions. In lower vertebrates, especially fish, increasing evidence suggests that PACAP may function as a hypophysiotropic factor regulating pituitary hormone secretion. PACAP has been identified in the brain-pituitary axis of representative fish species. The molecular structure of fish PACAP is highly homologous to mammalian PACAP. The prepro-PACAP in fish, however, is distinct from that of mammals as it also contains the sequence of fish GHRH. In teleosts, the anterior pituitary is under direct innervation of the hypothalamus and PACAP nerve fibers have been identified in the pars distalis. Using the goldfish as a fish model, mRNA transcripts of PACAP receptors, namely the PAC1 and VPACI receptors, have been identified in the pituitary as well as in various brain areas. Consistent with the pituitary expression of PACAP receptors, PACAP analogs are effective in stimulating growth hormone (GH) and gonadotropin (GTH)-II secretion in the goldfish both in vivo and in vitro. The GH-releasing action of PACAP is mediated via pituitary PAC1 receptors coupled to the adenylate cyclase-cAMP-protein kinase A and phospholipase C-IP3-protein kinase C pathways. Subsequent stimulation of Ca2+ entry through voltage-sensitive Ca2+ channels followed by activation of Ca2+-calmodulin protein kinase II is likely the downstream mechanism mediating PACAP-stimulated GH release in goldfish. Although the PACAP receptor subtype(s) and the associated post-receptor signaling events responsible for PACAP-stimulated GTH-II release have not been characterized in goldfish, these findings support the hypothesis that PACAP is produced in the hypothalamus and delivered to the anterior pituitary to regulate GH and GTH-II release in fish.

Carbopol/pluronic phase change solutions for ophthalmic drug delivery

The major purpose of this study is to develop and characterize a series of carbopol- and pluronic-based solutions as the in situ gelling vehicles for ophthalmic drug delivery. The rheological properties, in vitro release as well as in vivo pharmacological response of various polymer solutions, including carbopol, pluronic and carbopol/pluronic solution, were evaluated. It was found that the optimum concentration of carbopol solution for the in situ gel forming delivery systems was 0.3% (w/w), and that for pluronic solution was 14% (w/w). The mixture of 0.3% carbopol and 14% pluronic solutions showed a significant enhancement in gel strength in the physiological condition; this gel mixture was also found to be free flowing at pH 4.0 and 25 degrees C. The rheological behaviors of carbopol/pluronic solution were not affected by the incorporation of pilocarpine hydrochloride. Both the in vitro release and in vivo pharmacological studies indicated that the carbopol/pluronic solution had the better ability to retain drug than the carbopol or pluronic solutions alone. The results demonstrated that the carbopol/pluronic mixture can be used as an in situ gelling vehicle to enhance the ocular bioavailability.

Synergistic transcriptional activation by Sox10 and Sp1 family members

Neuronal nicotinic acetylcholine receptors (nAChR) are expressed at specific times during development and in discrete neuronal populations. Transcriptional regulation of the receptor genes clearly plays a key role in the molecular pathway underlying the expression of these critical synaptic components. In an effort to understand this regulation, we focus upon the genes encoding three receptor subunits: alpha3, alpha5 and beta4. These subunits are genomically clustered and constitute the predominant nAChR subtype expressed in the peripheral nervous system. We and others demonstrated that the general transcription factors, Sp1 and Sp3, can transactivate the promoter of each subunit gene. Further, we showed that the regulatory factor Sox10 transactivates the alpha3 and beta4 promoters and does so in a cell-type-specific manner. Interestingly, the Sp- and Sox10-binding sites on the beta4 promoter are located immediately adjacent to each other, raising the possibility that the two sets of factors functionally interact to regulate receptor gene expression. Consistent with this hypothesis, we demonstrated that the proteins can directly interact. Here, we extend these observations and show that Sox10 and the Sp factors functionally interact, leading to synergistic transcriptional activation in a cholinergic cell line. Finally, evidence for the existence of cell-type-specific co-regulators for Sp1 and Sox10 is presented.

Expression of grass carp growth hormone by baculovirus in silkworm larvae

A total of five recombinant Bombyx mori nuclear polyhedrosis viruses (BMNPV) carrying the grass carp (Ctenopharyngodon idellus) growth hormone (GH) cDNA were constructed in this study. Two of them were able to express the hormone up to a level of 12 microgram/ml medium when cultured B. mori cells were infected for 4 days. Inoculation of the viruses into silkworm (B. mori) host significantly increased the level of GH achievable. The amount of hormone produced per larva was estimated to be around 1 mg. The recombinant grass carp GH had immunological and biological activities similar to the native hormone. The N-terminal sequence of the recombinant hormone was the same as the native one, indicating that the fish signal peptide was correctly processed by the insect cells. Silkworm powder prepared from larvae infected with the recombinant virus was used as food supplement for fish. Compared with the control, this dietary supplement was effective in increasing the growth rate of juvenile carp.

Interleukin-1 beta (IL-1 beta) is increased in the follicular fluids of patients with premature luteinization

PROBLEM

Most, but not all, studies indicate that premature luteinization correlates with poor pregnancy outcome in in-vitro fertilization (IVF) programs. It remains unclear whether cytokines (IL-1 beta, TNF alpha), the established immune mediators, play a role in regulation or initiation of an abnormal follicular or embryo development in patients with premature luteinization.

METHODS

Levels of cytokines (IL-1 beta, TNF alpha), estradiol (E2) progesterone (P4), and androstenedione (A'ione) were examined in 18 preovulatory follicular fluid (FF) samples from patients with premature luteinization (group 1) and 3 FF samples from patients without premature luteinization (group 2). The number of oocytes recovered, fertilization rate, and pregnancy outcome were evaluated in these two groups.

RESULT

IL-1 beta (25.4 +/ 11.9 pg/ml, mean +/ SD) and TNF alpha (13.4 +/ 10.7 pg/ml) were present in these FF samples. The mean level of IL-1 beta in group 1 was significantly higher than that in group 2 (37.3 +/ 12.3 vs. 20.0 +/ 7.6 pg/ml; P < 0.00001) and the mean level of E2 was significantly lower in group 1 than that in group 2 (1064 +/ 686 vs. 1570 +/ 641 ng/ml; P = 0.02). The levels of TNF alpha, P4, and A'ione showed no distinction between these two groups. There was no correlation between the levels of either IL-1 beta or TNF alpha and P4, E2 or A'ione. The fertilization rate in group 1 (62/77; 80%) was similar to that in group 2 (124/160; 78%). Five of 7 patients in group 1 and seven of 20 patients in group 2 achieved pregnancy following embryo transfer. One of five pregnancies in group 1 aborted.

CONCLUSION

The exaggerated levels of IL-1 beta in patients with premature luteinization may arise from accumulation of this cytokine owing to sustained high LH stimulation, and this may be a protective response to the abnormal LH surge and function to inhibit prematurely increased secretion of P4. These data indicate the important role of LH in the induction of IL-1 beta secretion and the possible regulatory action of IL-1 beta in luteinization. According to the diminution of E2 in group 1, there may be a subtle atretic process progressing in follicles primed with prematurely elevated LH. However, the detrimental effect of premature luteinization, if it exists, may work at the stage ¿during or after implantation.

Postoperative diaphragmatic dysfunction in patients undergoing open-heart surgery

Diaphragmatic elevation after cardiac surgery may result in compromized post operative respiratory function, prolonged ventilator use, longer intensive care unit (ICU) stays, poor quality of life and even mortality. 200 patients receiving open-heart surgery during the two years from October 1990 to October 1992 were studied retrospectively. 26 patients developed postoperative diaphragmatic elevation (Group 2). On the other hand, 174 patients did not (Group 1). The mean age of Group 1 (37.3 +/- 20.0 years) was younger than that of Group 2 (57.4 +/- 9.1 years), P < 0.0001. The mean aortic cross-clamp time was 70.1 +/- 38.1 minutes in Group 1. On the other hand, Group 2 had a longer crossclamp time (84.5 +/- 31.3 Minutes), p < 0.03. Our study revealed that the patients who suffered post operative diaphragmatic dysfunction were older and had a longer aortic crossclamp time than the patients who did not.

Comparison between a two-layer discontinuous Percoll gradient and swim-up for sperm preparation on normal and abnormal semen samples

PURPOSE

This work was to compare the effects of Percoll gradient and swim-up treatments for sperm preparation on the percentage of progressive motility, recovery of motile sperm, removal of debris, percentage of normal forms according to strict criteria, and movement characteristics of sperm using computer-assisted velocity analysis.

RESULTS

In total, 50 semen samples from 50 patients were tested and divided into two groups: a normal group (n = 27) with normal parameters and an abnormal group (n = 23) with abnormal parameters. The results in both the normal and abnormal groups revealed that the sperm concentration in the Percoll samples was significantly greater than that in the swim-up samples. Although the percentage of progressive motility was greater in the swim-up samples than in the Percoll samples, the number of motile sperm, reflecting the percentage of motile sperm recovery, was till greater in the Percoll samples. The debris of semen was equally removed by both methods and the percentage of normal forms was also similar in the samples treated according to these two procedures. Both curvilinear velocity (VCL) and straight-line velocity (VSL) of sperm were significantly greater in the swim-up samples than in the Percoll samples. Sperm from the swim-up procedure also showed a greater mean amplitude of lateral head displacement than that from the Percoll gradient procedure, but the distinction was insignificant.

CONCLUSION

The Percoll gradient technique, by recovering more motile sperm, may be applied to prepare oligospermic samples. The swim-up method may become the standard choice to prepare normal semen which could obtain sufficiently motile sperm, due to its simplicity and recovered sperm with superior motility.

Correlation between sperm morphology using strict criteria in original semen and swim-up inseminate and human in vitro fertilization

To study the value of sperm morphology using strict criteria in raw semen and in swim-up inseminate of human in vitro fertilization (IVF), 135 cycles of IVF with normal sperm concentration and motility were recruited. At least two mature oocytes were recovered in each cycle. The correlation between the percentages of normal forms and fertilization rates of mature oocytes was analyzed. The results demonstrate that the percentage of normal forms in both the raw semen and swim-up sample of patients with poor fertilization was significantly lower than in those with acceptable fertilization. The percentages of normal forms both in raw semen and in swim-up sample were significantly correlated with fertilization rates in vitro, however, the former seemed to have a better correlation (r = .51 and .19, respectively). Regarding the percentages of normal forms in raw semen, the fertilization rate in patients with normal forms < 4% was 6 +/- 11%, for 4-14% it was 58 +/- 36%, and for > 14% it was 88 +/- 20%. The fertilization rates were significantly different among these three groups of patients. The evaluation of sperm morphology using strict criteria in raw semen before IVF is predictive of fertilization outcome and may also help doctors to choose an optimal method of treatment for patients.

Episodic growth hormone secretion in the grass carp, Ctenopharyngodon idellus (C. & V.)

The secretory pattern of growth hormone (GH) was studied in sexually immature grass carp (0.5-1.0 kg body wt). Serial blood samples were taken at 15-min intervals during 4- to 6-hr sampling periods via a dorsal aorta cannula. During each 4- to 6-hr sampling period plasma GH profiles demonstrated episodic secretion. Two patterns were observed, consisting either of one episodic of GH secretion (single or several pulses clustered) or two episodes of GH secretion during each sampling period. The interval between the two episodes of GH secretion was 2.6 hr. This is the first demonstration of episodic GH secretion in a teleost.

Co-culture with Vero cell monolayer maintains the motility of asthenozoospermic semen samples

The clinical effectiveness of co-culture with Vero (Green monkey kidney) cell monolayer in maintaining the motility and viability of fresh asthenozoospermic semen (18 samples) and frozen-thawed semen with poor motility (motility fraction < 50%) (15 samples) in a 24-h period was evaluated. Co-culture with Vero cell monolayer in human tubal fluid (HTF) medium for 24 h resulted in a statistically better maintenance of motility percentage (P < 0.005), mean amplitude of lateral head displacement (ALH) (P < 0.005), and mean track speed (VCL) (P < 0.05) than culture in HTF medium alone. However, these motility parameters (motility percentage, ALH, VCL) declined soon after removal of spermatozoa from the monolayer. Co-culture with Vero cell monolayer also maintained the viability percentage of these sperm samples (52% of the original value) after the 24-h period compared with culture in HTF medium alone (22% of the original) (52% versus 22%, P < 0.05). It is concluded that Vero cell monolayer is effective in the maintenance of motility and viability of asthenozoospermic semen or frozen-thawed semen with poor motility. This co-culture system may be beneficial in enhancing the in-vitro performance of asthenozoospermic semen samples in the practice of assisted reproductive technology. However, its safety needs further evaluation.

Peptides extracted from Vero cell cultures overcome the blastocyst block of mouse embryos in a serum-free medium

PURPOSE

The aim of this work was to evaluate the effect of a Vero cell coculture system on the development of mouse embryos.

METHODS

Mouse embryos were randomly divided and cultured in human tubal fluid (HTF) medium with/without Vero cell monolayers, conditioned medium (CM) obtained from Vero cell cultures, and HTF medium supplemented with peptides extracted from CM. The concentrated CM was examined by SDS/PAGE.

RESULTS

The development of mouse embryos was blocked at the blastocyst stage in pure HTF medium (1.4% hatching at day 5). This "blastocyst block" was overcome by coculture with Vero cell monolayers (48.1% hatching at day 5; 1.4 vs 48.1%; P < 0.001). CM and the addition of 5% fetal bovine serum (24.1 and 34.9% hatching, respectively, at day 5) were also able to enhance the process of hatching. In the other experiment, the addition of peptides extracted from Vero cell cultures also overcame the blastocyst block (12.5%) compared with pure HTF medium (2.1%) (P < 0.05). Electrophoretic separation revealed several classes of polypeptides consistently secreted into CM obtained from Vero cell cultures. Most peptides occurred in the M(r) range between 6.5 kd and 35.9 kd.

CONCLUSION

A developmental block (blastocyst block) of mouse embryos in a serum- and protein-free medium (HTF) was discovered in this study. This block was effectively overcome by HTF plus serum and coculture with Vero cell monolayers and also by the peptides extracted from Vero cell-conditioned medium. We speculate that certain factors secreted or converted by Vero cells may be critical in hatching of mouse embryos. Further study of these factors may be helpful in delineating its mechanism.

Seasonal variations in gonadotropin responsiveness, self-priming, and desensitization to GnRH peptides in the common carp pituitary in vitro

Seasonal variations of the GtH release response to salmon GnRH (sGnRH) and [D-Arg6,Pro9NEt]-sGnRH (sGnRH-A) were investigated in female common carp at different stages of the reproductive cycle using perifused pituitary fragments. The responsiveness to sGnRH and sGnRH-A varied seasonally in common carp pituitaries in vitro, with the greatest GtH release response in pituitaries from sexually mature (preovulatory) fish compared to pituitaries from sexually regressed fish. The magnitude of this seasonal change in the GtH release response was greater for sGnRH-A than for sGnRH, and sGnRH-A has a higher potency than sGnRH, particularly in pituitaries from sexually mature fish. Desensitization of perifused pituitary fragments to sGnRH and sGnRH-A, and a self-priming effect of sGnRH-A on the GtH release response, caused by repeated pulse administrations of the GnRH peptides, varied with the stage of reproductive cycle of the common carp. Using pituitaries from sexually regressed female common carp, desensitization occurred only when a high dose of sGnRH or sGnRH-A was given as repeated pulses at short time intervals, and no self-priming was observed by repeated administrations of sGnRH and sGnRH-A. Using pituitaries from sexually mature female common carp, desensitization occurred when a high dose of sGnRH and both high and low dosages of sGnRH-A were given as repeated pulses at short time intervals. Self-priming, largely due to the increase in basal GtH levels, occurred in response to repeated pulses of low dosages of sGnRH-A given at long intervals.

Acrosin activity of human sperm did not correlate with IVF

To evaluate the predicting value of sperm acrosin activity in human, the acrosin activity index (AAI) was measured in 95 semen samples from patients participating in an IVF program. All patients had at least two mature oocytes. Of 95 patients, 84 had successful fertilization and 11 failed to fertilize all oocytes in vitro. The numbers of mature oocytes were similar between fertilization and nonfertilization groups. The mean AAI, measured using a commercially available (Accu-Sperm) acrosin activity assay, was greater in the fertilization group than in the nonfertilization group, but the difference was not significant. There was no correlation between AAI and the in vitro fertilization rate of mature oocytes. The relation between AAI and semen parameters also showed no significant difference. It would appear that measurement of AAI inaccurately reflects in vitro fertilizability of human sperm.

Sharing of human leukocyte antigens in couples with unexplained infertility affects the success of in vitro fertilization and tubal embryo transfer

OBJECTIVE

The purpose was to test further our hypothesis that genes, or genetic defects, linked to the major histocompatibility complex affect reproduction by correlating human leukocyte antigen sharing with the success or failure of in vitro fertilization and tubal embryo transfer in couples having unexplained infertility.

STUDY DESIGN

Seventy-six couples with unexplained infertility who failed superovulation and intrauterine insemination at least three times were typed for human leukocyte antigens and treated by in vitro fertilization and tubal embryo transfer. The results were correlated with the sharing of human leukocyte antigens in the couples.

RESULTS

Thirty-four of the women had successful pregnancies, 36 did not become pregnant, and six became pregnant but aborted shortly thereafter. There was a highly significant excess of human leukocyte antigen sharing in the couples who failed treatment: three of the A, B, DR, and DQ antigens (p = 0.015) or two of the B, DR, and DQ antigens (p = 0.015). No specific human leukocyte antigen alleles were present in excess.

CONCLUSIONS

Genes, or genetic defects, linked to the major histocompatibility complex significantly affect the success of in vitro fertilization and tubal embryo transfer just as they affect the prevalence of recurrent spontaneous abortion, cancer, and congenital anomalies. It appears as if the critical genes, or genetic defects, are located in the B-DR-DQ region of the major histocompatibility complex.

The regulatory effects of thyrotropin-releasing hormone on growth hormone secretion from the pituitary of common carp in vitro

The effects of thyrotropin-releasing hormone (TRH) on growth hormone (GH) and gonadotropin (GtH) release, and the influences of somatostatin (SRIF), the dopamine agonist apomorphine (APO) and extracellular calcium on basal and TRH-induced GH release were examined using an in vitro perifusion system for pituitary fragments of common carp (Cyprinus carpio). Five minute pulses of different dosages of TRH stimulated a rapid and dose-dependent increase in GH release from the perifused pituitary fragments with an ED50 of 9.7 ± 2.3 nM. TRH was ineffective on GtH release. SRIF significantly inhibited basal and TRH-induced GH release from the perifused pituitary fragments, and the effects of SRIF were dose-dependent. APO induced a dose-dependent increase in basal and TRH-stimulated GH release from the perifused pituitary fragments. Increasing the concentrations of extracellular calcium from 0 mM to 1.25 mM resulted in an increase in basal and TRH-induced GH release. The high dose of calcium (6.25 mM) caused a slight decrease in basal and TRH-induced GH release compared with those at a concentration of 1.25 mM.

Microinjection of human sperm into perivitelline space of hamster eggs: comparison with zona-free hamster egg penetration of human sperm

Micromanipulation of human sperm and oocyte has been utilized to facilitate fertilization of those patients with male factor due to oligoasthenospermia or those patients with repeated fertilization failure in an in vitro fertilization (IVF) program. Before manipulating human gametes, one needs experience with animal models. Our objective was to perform subzonal insertion of human sperm into hamster eggs and to compare the result with that of sperm penetration assay (SPA) using zona-free hamster eggs. Semen samples were obtained from 15 fertile donors with normal semen analysis and the motile sperm were collected by swim-up procedure. Microinjection was performed by injecting a varied number of sperm into the perivitelline space of 222 hamster eggs pretreated with sucrose solution (0.1 M). The rate of damage of eggs during microinjection was 7.2% (16/222). The rates of penetration in the microinjection group were 5.1% (4/79) for 1-5 sperm injected, 10.9% (11/101) for 6-10 sperm injected, and 11.5% (3/26) for 11-15 sperm injected. The average rate of penetration per egg was 8.7% (18/206), and the polyspermic rate was 11.1% (2/18). Simultaneously SPA was performed in each sample of semen as a positive control, and the average rate of penetration of SPA was 51.4% (108/210). The rate of penetration in the microinjection group was significantly smaller (p < .05) than that in the SPA group. Whether the penetration rate and polyspermic rate in a hamster model reflect similar results in human oocyte requires further investigation. However, the hamster egg provides an ideal model to develop a micromanipulation technique for human beings.

Analysis of human in vitro fertilization failure

Fertilization failure is a serious problem in human in vitro fertilization (IVF) programs and deserves further investigation and management. Two hundred and ninety-four IVF cycles performed at the National Taiwan University Hospital from July 1989 to June 1991 were retrospectively analyzed. Thirty-seven (13%) of the 294 cycles were observed to have fertilization failure. The incidence of fertilization failure in male factor patients was significantly higher (p < 0.05) than in others. Patients with oligoasthenospermia tended to have a higher rate of fertilization failure than patients with oligospermia or asthenospermia alone. In non-male factor patients, a smaller number of oocytes and mature oocytes was found in patients with fertilization failure than in patients achieving fertilization. Sperm penetration assay (SPA) using zona-free hamster eggs was performed for 15 patients with fertilization failure; no correlation was found between SPA and the fertilizing ability of the sperm in vitro. Four patients with severe oligoasthenospermia had repeated fertilization failure in subsequent IVF cycles. The other five patients, including four non-male factor patients and one male factor patient, achieved fertilization in their second IVF trial. Our results suggest that severe oligoasthenospermic patients with repeated fertilization failure should be candidates for micromanipulation of gametes in subsequent IVF trials.

Growth hormone and gonadotropin secretion in the common carp (Cyprinus carpio L.): in vitro interactions of gonadotropin-releasing hormone, somatostatin, and the dopamine agonist apomorphine

The effects of salmon gonadotropin-releasing hormone (sGnRH) and the superactive agonist [D-Arg6, Pro9NEt]-sGnRH (sGnRH-A) on growth hormone (GH) and gonadotropin (GtH) release were examined using a perifusion system for pituitary fragments of the common carp (Cyprinus carpio). Perifusion of 2-min pulses of different concentrations of sGnRH or sGnRH-A stimulated a rapid and dose-dependent increase in GH release: ED50 values for sGnRH and sGnRH-A in stimulating GH release were 2.8 +/- 0.7 and 0.5 +/- 0.1 nM, respectively, indicating that the superactivity of sGnRH-A for stimulation of GtH release also applies in induction of GH release. Exposure of the pituitary fragments to 10 nM sGnRH or sGnRH-A alone resulted in increases in GH and GtH release on a similar temporal course. Apomorphine (10, 100, and 1000 nM) significantly inhibited basal and GnRH-induced GtH release in a dose-dependent manner and significantly stimulated basal GH release; however, APO did not enhance GnRH-induced GH release. Somatostatin (100 nM) significantly blocked basal release and 10 nM sGnRH- and sGnRH-A-induced GH release, but was ineffective on GtH release. Treatment with somatostatin (100 nM) in combination with apomorphine (100 nM) caused an increase in sGnRH-induced GH release compared to treatment with somatostatin alone; whereas, on GtH there was a significant decrease in basal and GnRH-induced levels, compared to treatment with somatostatin alone. These results indicate that GH release in common carp is regulated by somatostatin as GH release inhibitor. sGnRH and sGnRH-A act as GH-releasing factors; the mechanisms by which GnRH stimulates GH and GtH secretion are independent. The dopamine agonist apomorphine stimulates GH release and inhibits GtH release directly at the pituitary level.

Effect of the number and depth of embryos transferred and unilateral or bilateral transfer in tubal embryo transfer (TET)

PURPOSE

Our purpose was to evaluate the possible effects of the number of embryos transferred, the depth of embryos placed within the tube(s), and unilateral or bilateral tubal transfer on pregnancy initiation in tubal embryo transfer (TET).

METHODS

One hundred eight consecutive TET cycles were analyzed. Oocyte retrievals were carried out by transvaginal ultrasound-guided aspiration of follicles. Forty-eight hours after oocyte retrieval, the developing embryos at the stage of two to four cells were transferred into the fallopian tube(s) by laparoscopy. A maximum of four embryos was transferred to each patient.

RESULTS

The pregnancy rates were similar among the cycles in which two, three, or four embryos were transferred. In addition, there was no significant difference in the pregnancy rate whether the embryos were deposited > 4 cm or between 3 and 4 cm into the tube(s). Although the pregnancy rate was greater in cycles of bilateral tubal transfer, the difference from that of unilateral transfers was not significant.

CONCLUSION

Our data indicate that when two to four embryos were transferred and the embryos were placed > or = 3 cm within the tube(s), unilateral or bilateral tubal transfer had little influence on the ultimate success of TET.

Pregnancy after transfer of frozen-thawed human embryos

Cryopreservation of human embryos has been successfully applied in in vitro fertilization (IVF) and embryo transfer (ET) programs at the National Taiwan University Hospital since 1988. Our preliminary results with 120 frozen-thawed embryos in 31 transfer cycles showed that the survival rate of frozen embryos was 66%. Following transfer, the implantation rate and clinical pregnancy rate were 6.5% and 13%, respectively. Four clinical pregnancies and one preclinical pregnancy following a frozen-thawed embryo transfer were achieved. Two normal male babies have been delivered and another pregnancy is progressing without any problem.* Unfortunately, one pregnancy was terminated due to intrauterine fetal death discovered at the 10th week of gestation; chromosome abnormality (47, XX, +5) of the fetus was found. The single preclinical pregnancy showed an elevation of serum beta-human chorionic gonadotropin levels for three consecutive weeks following ET, but no definite gestational sac was visualized by transvaginal ultrasound.

The use of a long-acting gonadotropin-releasing hormone analog(D-Trp-6-LHRH) for improvement of ovarian stimulation in assisted conception programs

To assess the efficacy of gonadotropin-releasing hormone analog (GnRHa) as an adjuvant in controlled ovarian stimulation in assisted conception programs, 114 infertile patients, who were treated by in vitro fertilization and embryo transfer (n = 61) or tubal embryo transfer (n = 53), were randomized sequentially to receive ovarian stimulation according to two protocols. In protocol 1 (n = 57), long-acting GnRHa (D-Trp-6-LHRH) microcapsules were administered intramuscularly at menstruation and ovarian stimulation using follicle-stimulating hormone (FSH) and human menopausal gonadotropin (hMG) was started 2 to 3 weeks later when the pituitary was completely suppressed. In protocol 2 (n = 57), patients received FSH and hMG from day 3 of the cycle without GnRHa pre-treatment. We found that premature luteinization did not occur in patients treated with protocol 1, and the number of cycles cancelled was also decreased. The days of ovarian stimulation and the amount of hMG required to achieve adequate follicular development were significantly higher in protocol 1 than that in protocol 2. Similarly, the mean serum estradiol levels on the day of human chorionic gonadotropin administration, number of large follicles (mean diameter greater than 10 mm), number of oocytes recovered and number of embryos obtained were also significantly higher in patients treated with protocol 1. The data suggest that the use of D-Trp-6-LHRH as an adjuvant in ovarian stimulation is associated with a lower incidence of cycle cancellation and an improvement in ovarian response in assisted conception programs.

Translaparoscopic tubal embryo transfer: preliminary experience at National Taiwan University Hospital

Forty-six couples with various causes of infertility were treated by tubal embryo transfer. Oocyte retrievals were carried out under ultrasound guidance transvaginally and embryos were transferred 48 hours later by laparoscopy into fallopian tubes. Totally 52 cycles were stimulated and 45 retrievals were performed with an average of 8.1 oocytes per retrieval. The average fertilization rate was 54.8%. The implantation rate was 23.8% and the pregnancy rate was 53.5% per transfer. The pregnancy rate per transfer was comparable whether 3 or 4 embryos were transferred. Nine (39.1%) of the 23 pregnancies had multiple pregnancies. Six cases (26.1%) aborted in the first trimester and the remaining 17 were ongoing or term delivery.

Treatment of patients with unexplained infertility: gamete intrafallopian transfer (GIFT) versus tubal embryo transfer (TET)

This study compares the results of 65 cycles of gamete intrafallopian transfer (GIFT), and 19 cycles of tubal embryo transfer (TET) in couples with unexplained infertility (UI). Oocyte retrievals were carried out by laparoscopy in GIFT and transvaginally in TET, in which the embryos were transferred by laparoscopy into the fallopian tubes 48 hours later. The mean age, duration of infertility, serum estradiol levels on the day of human chorionic gonadotropin administration, number of large follicles (mean diameter greater than 10 mm) and the number of oocytes recovered were similar between these two groups. From the 65 GIFT cycles, 20 clinical pregnancies resulted (30.8%). From the 19 cycles of TET, 10 conceptions occurred (52.6%). The implantation and pregnancy rates after TET were higher than that after GIFT, but the differences were not statistically significant. The data suggest that GIFT has a similar success rate to TET in couples with UI.

Dopamine inhibits gonadotropin secretion in the Chinese loach (Paramisgurnus dabryanus)

The effects of dopamine on gonadotropin (GtH) secretion in sexually mature Chinese loach were investigated. Spontaneous secretion of GtH was inhibited within 1 h following an intramuscular injection of dopamine (100 μg/g body wt). Similarly, dopamine (50 and 100 μg/g body wt) caused a significant reduction in serum GtH in fish with elevated GtH levels as a result of pretreatment with gonadotropin-releasing hormone (GnRH) analogs either alone or in combination with the dopamine receptor antagonist domperidone. In summary, the present study provides direct evidence that dopamine functions as a gonadotropin-release inhibitory factor in the Chinese loach by blocking spontaneous and GnRH-stimulated GtH release.

Effects of [D-Arg6, Trp7, Leu8, Pro9NEt]-luteinizing hormone-releasing hormone (sGnRH-A) and [D-Ala6, Pro9NEt]-luteinizing hormone-releasing hormone (LHRH-A), in combination with pimozide or domperidone, on gonadotropin release and ovulation in the Chinese loach and common carp

The effects of LHRH-A and sGnRH-A alone and in combination with the dopamine receptor antagonists pimozide (PIM) and domperidone (DOM) on stimulation of gonadotropin (GtH) secretion and ovulation in Chinese loach (Paramisgurnus dabryanus) and common carp (Cyprinus carpio) were studied. When tested in the absence of a dopamine receptor antagonist, sGnRH-A was about 10-fold more potent than LHRH-A in stimulating GtH secretion in loach, whereas these peptides were of similar effectiveness in common carp. Both peptides were effective alone in inducing ovulation in loach, but were ineffective in common carp. PIM and DOM stimulate a small but significant increase in serum GtH, and greatly potentiate the effects of LHRH-A and sGnRH-A on GtH secretion and ovulation in both species. DOM was of equal or somewhat greater potency than PIM in potentiating the action of releasing hormone agonists in loach; however, DOM had markedly greater effectiveness in common carp. sGnRH-A in the presence of DOM was more effective than LHRH-A in stimulating GtH secretion and ovulation in common carp. The present studies suggest that there are marked differences in the relative contribution of GnRH and dopamine in the control of GtH secretion in loach and common carp, and indicate in particular that the more intense dopaminergic inhibitory control of GtH release in common carp modifies the responsiveness of the pituitary to GnRH peptides.

Primary structure of common carp prolactins

The complete amino acid sequence of common carp (Cyprinus carpio) prolactin (PRL) has been determined. One milligram of carp PRL was reduced, carboxymethylated, and then cleaved with cyanogen bromide and several enzymes. Another milligram of carp PRL was digested with lysyl endopeptidase. The resulting fragments were separated by reverse-phase high-performance liquid chromatography and subjected to sequence analysis by the automatic Edman method with a gas-liquid sequencer and the manual DNS-Edman method. The carp PRL consists of 186 amino acid residues with two disulfide linkages formed between residues 46-160 and 177-186. In addition, it lacks the linkage in the amino-terminal portion of mammalian prolactins, as do salmon and tilapia PRLs, and shows 77% sequence identity with salmon PRL and 36% identity with mammalian PRLs. The sequence comparison has been performed with 190 alignment positions. Four conserved segments of the alignment positions 1-32, 46-66, 71-94, and 155-182 that were found between salmon and mammalian PRLs are further confirmed in carp PRL. Variant residues are clustered in the region of residues 98-143 which has 48% sequence identity with salmon PRL and only 2% with mammalian PRL.

Effects of [D-Ala6, Pro9-NEt]-LHRH and catecholaminergic drugs on gonadotropin secretion and ovulation in the Chinese loach (Paramisgurnus dabryanus)

The effects of [D-Ala6,Pro9-NEt]-LHRH (LHRH-A) alone and in combination with drugs which influence the actions of dopamine or the synthesis of catecholamines on gonadotropin (GtH) secretion and ovulation in the loach (Paramisgurnus dabryanus) were investigated. LHRH-A alone stimulated an increase in serum GtH levels in the loach, but was a relatively ineffective treatment for the induction of ovulation. Injection of the dopamine receptor antagonist pimozide caused a marked potentiation of the GtH-release response to LHRH-A, and combined injections of pimozide and LHRH-A were an effective treatment for the induction of ovulation. Reserpine, a drug which causes depletion of catecholamines from presynaptic terminals, also caused a marked potentiation of the GtH-release response to LHRH-A and combined treatment induced ovulation. Similarly, administration of alpha-methyl-para-tyrosine to block conversion of tyrosine to L-dopa, or carbidopa to block conversion of L-dopa to dopamine, potentiated the GtH-release response to LHRH-A and induced ovulation. In contrast, the use of diethyldithiocarbamate, to block conversion of dopamine to norepinephrine, failed to augment the action of LHRH-A on GtH release and ovulation. The present results provide further evidence to suggest that dopamine functions as a gonadotropin release-inhibitory factor in teleosts, and demonstrate that the use of drugs which block either the synthesis or the actions of dopamine potentiates the action of LHRH-A in teleosts.

Effects of LH-RH and des-Gly10[D-Ala6]LH-RH-ethylamide on plasma gonadotropin levels and oocyte maturation in adult female coho salmon (Oncorhynchus kisutch)

Plasma gonadotropin (GtH) levels and state of oocyte development were determined in adult female coho salmon following single intraperitoneal injections of LH-RH or its superactive analog des-Gly10[D-Ala6]LH-RH-ethylamide (LH-RHA DAla6). The peptides injected at dosages of 1.0 or 0.2 mg LH-RH and 0.2 or 0.02 mg LH-RHA DAla6/kg bw elevated plasma GtH by 1.5 hr postinjection. The response to the analog was of longer duration. Plasma GtH levels returned to basal levels 24 hr following LH-RH injection while elevated plasma GtH levels were maintained for at least 96 hr in response to the analog. Only those fish injected with LH-RHA DAla6 showed an accelerated rate of germinal vesicle breakdown (GVBD). Based on their relative effects on GVBD, LH-RHA DAla6 has at least 50 times the biological potency of LH-RH in adult female coho salmon.

Studies on mechanism of action of luteinizing releasing hormone (LH-RH) in ovulation of fish--intracellular distribution of LH-RH-A in pituitary gonadotrophs as revealed by electron-microscopic autoradiography

The results of competitive bending experiment and the electron-microscopic autoradiographic studies show that the peptide hormone, LH-RH-A (a nonapeptide), could be internalized into the gonadotrophs of the pituitary gland of the mud-carp (Cirrhrinus molitorella). It is demonstrated that the labeled peptide, 125I-LH-RH-A, is internalized not only into the cytoplasm, but also into the nucleus, apparently via the nuclear pores. It is, therefore, suggested that the peptide hormone might act directly on the genome either in the form of a hormone-receptor complex or of a single molecule.