Chicken oviduct-the target tissue for growth hormone action: effect on cell proliferation and apoptosis and on the gene expression of some oviduct-specific proteins

Effects of Bacillus subtilis Natto NB205 and Its Mutant NBMK308 on Egg Quality in Aging Laying Hens

In aging laying hens, reproductive changes reduce egg quality. Bacillus subtilis natto (B. subtilis) is a versatile bacterium with high vitamin K2 content, providing health benefits for animals and humans. This study investigated the effect of B. subtilis natto NB205 and its mutant NBMK308 on egg quality in aging laying hens. Results showed that NB205 and NBMK308 supplementation significantly improved albumen height (p < 0.001), Haugh units (p < 0.05), and eggshell thickness (p < 0.001) compared to the control group. Supplementation also increased ovalbumin expression, regulated tight junction (TJ) proteins, reduced pro-inflammatory cytokine levels, and improved the health and productivity of aging laying hens by regulating key apoptosis-related genes in the magnum part of the oviduct. There were differences in the expression of vitamin K-dependent proteins (VKDPs) in the magnum between NB205 and NBMK308, but no significant differences in the improvement of egg quality. Supplementation with NB205 and NBMK308 can improve egg quality in aging laying hens.

Identification of key genes and biological pathways in different parts of yak oviduct based on transcriptome analysis

The oviduct consists of three parts: the infundibulum (In), ampulla (Am), and isthmus (Is). These have the same histological structure, but different physiological functions. In this study, transcriptomics was used to analyze mRNA in these three parts of yak oviduct. The results showed that there were 325 up-regulated genes and 282 down-regulated genes in the infundibulum and ampulla. Moreover, there were 234 up-regulated genes and 776 down-regulated genes in the isthmus and ampulla, as well as 873 up-regulated genes and 297 down-regulated genes in the infundibulum and isthmus. The expression of C3 in the infundibulum was significantly higher than that in the ampulla and isthmus. The expression of FAU in the isthmus was significantly lower than that in the ampulla and infundibulum, and the expression of EEF1A1 in the ampulla was significantly higher than that in the ampulla and infundibulum. When the infundibulum was compared with the ampulla and isthmus, it was found that the up-regulated genes were enriched in the lysosome, phagosome, staphylococcus aureus infection, and leishmaniasis pathway. When the isthmus was compared with the ampulla and infundibulum, the up-regulated genes were present in the apoptosis pathway, oxidative phosphorylation, and viral myocarditis pathway. When the isthmus was compared with the infundibulum and ampulla, the down-regulated pathways were protein processing in the endoplasmic reticulum and the endocytosis. The Epstein-Barr virus infection pathway was up-regulated according to a comparison of the isthmus and infundibulum and was down-regulated based on a comparison of the isthmus and ampulla. Transcriptional misregulation in the Middle East pathway was up-regulated based on a comparison of the isthmus and ampulla and was down-regulated based on a comparison of the isthmus and infundibulum. ERBB2, JUP, CTNND1, and KRT7 were defined as the hub genes of the yak oviduct. The results of this study provide sufficient omics data for yak fertilization, which is also of great significance to altitude medicine.

Regulation of ovarian function by growth hormone: Potential intervention of ovarian aging

Growth hormone (GH) is mainly secreted by eosinophils of anterior pituitary gland. GH plays an important role in regulating the growth and development of many tissues and cells, so it is used in the treatment of many diseases. In recent years, the regulation of GH on ovarian function has attracted much attention. GH has been applied in controlled ovarian hyperstimulation, particularly in the patients with advanced age, diminished ovarian reserve (DOR) and poor ovarian response (POR). GH can directly bind to the growth hormone receptor (GHR) on the ovary to promote the growth, maturation and ovulation of follicles, as well as to inhibit follicular atresia. GH so as to promote the occurrence of early follicles, enhance the sensitivity of follicles to gonadotropins, accelerate the maturation of oocyte nucleus, improve mitochondrial activity and the quality of oocytes through the insulin-like growth factor (IGF) system, which is an indirect regulation. The deep-seated effects of GH on human reproduction and ovarian aging need further basic research and clinical practice.

Polymorphism analysis and expression profile of the estrogen receptor 2 gene in Leizhou black duck

Our previous study on the ovarian transcriptomic analysis in Leizhou black duck revealed that the ESR2 gene was involved in hormone regulation in reproduction and the estrogen signaling pathway related to reproductive performance was enriched. This suggested that ESR2 may have a functional role in the reproductive performance of the Leizhou black duck. Thus, this study aimed at evaluating the polymorphism of the ESR2 gene and its association with egg-laying traits and the distribution pattern of ESR2 mRNA in laying and non-laying Leizhou black ducks. In this study, genomic DNA was extracted from blood samples of 101 Leizhou black ducks to identify single nucleotide polymorphisms (SNPs) of the ESR2 gene to elucidate molecular markers highly associated with egg-laying traits. Four each of laying and non-laying Leizhou black ducks were selected to collect different tissues to analyze the ESR2 gene expression. A total of 23 SNPs were identified and association analysis of the single SNP sites showed that SNPs g.56805646 T>C and exon 3-20G>A were significantly (P < 0.05) associated with egg weight. Ducks with CT and AG genotypes had significantly higher (P < 0.05) egg weights than their respective other genotypes. Haplotype association analysis of g.56805646 T>C and exon 3-20G>A showed that the haplotypes were significantly associated with egg weight. Higher egg weight was seen in individuals with H3H4 haplotypes. In the hypothalamus-pituitary-gonadal (HPG) axis, the results of qRT/PCR showed that ESR2 mRNA was significantly (P < 0.05) expressed in the ovaries of both duck groups than in the hypothalamus and pituitary. In the oviduct, ESR2 was significantly (P < 0.05) higher in the infundibulum and magnum of laying and non-laying ducks respectively. This study provides a molecular marker for selecting Leizhou black ducks for egg production. In addition, it offers theoretical knowledge for studying the related biological functions of the ESR2 gene at the cellular level.

Association of female reproductive tract microbiota with egg production in layer chickens

BACKGROUND

The microbiota of the female reproductive tract is increasingly recognized as playing fundamental roles in animal reproduction. To explore the relative contribution of reproductive tract microbiomes to egg production in chickens, we investigated the microbiota in multiple reproductive and digestive tract sites from 128 female layer (egg-producing) chickens in comparable environments.

RESULTS

We identified substantial differences between the diversity, composition, and predicted function of site-associated microbiota. Differences in reproductive tract microbiota were more strongly associated with egg production than those in the digestive tract. We identified 4 reproductive tract microbial species, Bacteroides fragilis, Bacteroides salanitronis, Bacteroides barnesiae, and Clostridium leptum, that were related to immune function and potentially contribute to enhanced egg production.

CONCLUSIONS

These findings provide insights into the diverse microbiota characteristics of reproductive and digestive tracts and may help in designing strategies for controlling and manipulating chicken reproductive tract microbiota to improve egg production.

Effect of organic and inorganic dietary selenium supplementation on gene expression in oviduct tissues and Selenoproteins gene expression in Lohman Brown-classic laying hens

Background

The oviduct of a hen provides a conducive environment for egg formation, which needs a large amount of mineral elements from the blood via trans-epithelial permeability. Eggshell is the calcified layer on the outside of an egg that provides protection and is critical for egg quality. However, little is known about the genes or proteins involved in eggshell formation, and their relationship to dietary microminerals. We hypothesized that dietary selenium supplementation in chickens will influence genes involved in eggshell biomineralization, and improve laying hen antioxidant capacity. The objective of this research was to investigate how organic and inorganic dietary selenium supplementation affected mRNA expression of shell gland genes involved in eggshell biomineralization, and selenoproteins gene expression in Lohman Brown-Classic laying hens.

Results

Shell gland (Uterus) and liver tissue samples were collected from hens during the active growth phase of calcification (15–20 h post-ovulation) for RT-PCR analysis. In the oviduct (shell gland and magnum) and liver of laying hens, the relative expression of functional eggshell and hepatic selenoproteins genes was investigated. Results of qPCR confirmed the higher (p < 0.05) mRNA expression of OC-17 and OC-116 in shell gland of organic Se hen compared to inorganic and basal diet treatments. Similarly, dietary Se treatments affected the mRNA expression of OCX-32 and OCX-36 in the shell gland of laying hens. In the magnum, mRNA expression of OC-17 was significantly (p < 0.05) higher in hens fed-bacterial organic, while OC-116 mRNA expression was down-regulated in dietary Se supplemented groups compared to non-Se supplemented hens. Moreover, when compared to sodium selenite, only ADS18 bacterial Se showed significantly (p < 0.05) higher mRNA levels in GPX1, GPX4, DIO1, DIO2 and SELW1, while Se-yeast showed significantly (p < 0.05) higher mRNA levels in TXNRD1 than the non-Se group.

Conclusions

Dietary Se supplementation especially that from a bacterial organic source, improved shell gland and hepatic selenoproteins gene expression in laying hens, indicating that it could be used as a viable alternative source of Se in laying hens. The findings could suggest that organic Se upregulation of shell gland genes and hepatic selenoproteins in laying hens is efficient.

Expression of estrogen receptor alpha in response to stress and estrogen antagonist tamoxifen in the shell gland of Gallus gallus domesticus: involvement of anti-oxidant system and estrogen

Animals are frequently exposed to various kinds of environmental stressors and estrogen is known to play important role in stress response besides its crucial role in regulation of cellular proliferation, metabolic activity and reproduction. The study investigates the estrogen antagonist, tamoxifen (TM), mediated estrogen receptor alpha (ERα) expression, to modulate stress induced parameters in chickens. The study further explores the activity of superoxide dismutase (SOD), catalase and glutathione peroxidase (GPX) and malonaldehyde (MDA) in brain, ovary and shell gland during water deprivation (WD) and tamoxifen administration in sexually mature chicken. WD and TM administration both decrease the plasma estradiol while WD increases corticosterone. WD also elevates MDA concentration in the brain, ovary and shell gland while TM lowers it. WD and TM administration lowers the specific activity of SOD in brain and shell gland. In contrast, WD increases the specific activity of catalase, GPx and GR in the brain and shell gland, while TM decreases it. It appears that endogenous estradiol plays a crucial role in expression of antioxidant enzymes and tamoxifen acts as an antioxidant by reducing the oxidative stress in chicken. Abundant expression of ERα has been observed in the shell gland of egg laying birds while stress like water deprivation and TM down-regulates its expression. Thus, it can be concluded that expression of ERα in shell gland plays a predominant role in mediating estrogen action in response to water deprivation stress and tamoxifen.

Effect of Supplementation of Fermented Yeast Culture on Hormones and Their Receptors on Exposure to Higher Temperature and on Production Performance after Exposure in Nicobari Chickens

Heat stress (HS) affects the production performance in chickens and causes economic loss to the producers. Most of the studies have been conducted on and for the welfare of broilers. We still lack information on the physiological parameters being affected during chronic heat stress in layers. To fill this gap, the present study evaluated the effect of heat stress (induced in the chamber) during the prelaying period (21-23 weeks) on plasma levels of the hormones leptin and ghrelin and GH and expression of the respective receptors and heat stress markers. Three groups were considered, one at room temperature (CR) and the other two groups (SH and CH) subjected to heat stress at 39°C for four hours for three weeks (21-23 weeks of age). The SH group (SH) feed was supplemented with fermented yeast culture (FYC, 700 mg/kg), whereas the CH group was devoid of it. After that, all the groups were shifted to shed under natural ambient conditions till 31 weeks of age. Studies were restricted to production performance only. Feed offered without yeast culture (CH group) had a smaller concentration of plasma hormones (P < 0.01) and increased expression fold of the hormone receptors (P < 0.01). Further, the group also presented higher liver AMP kinase enzyme, plasma MDA (malondialdehyde), and cholesterol concentrations. These changes likely explained the decrease in feed intake and the CH group's body weight and further reduced the production performance during the laying period. Supplementation with FYC to birds had an opposite effect on the above-mentioned parameters, reducing HS effects. In summary, supplementation with FYC (700 mg/kg) maintained physiological parameters as in the CR group under HS conditions and negated adverse effects on parameters both before and during laying periods.

Zinc, manganese and copper amino acid complexed in laying hens' diets affect performance, blood parameters and reproductive organs development

In the intestinal lumen, excess of oxides and sulfates interfere with the absorption of minerals due to competition from the same absorption site. Amino acids-mineral complexed (AACM) is intended to minimize these problems, which might be absorbed by different absorption sites. Then, a study including Zinc (Zn), Manganese (Mn) and Copper (Cu) from different sources was carried out to evaluate the performance, blood parameters and reproductive organs development of Brown Laying Hens. A total of 800 Lohmann Brown Lite were fed, from one-day-old to 182-days-old, Zn, Mn and Cu from different sources. Measurements were made from 105 to 182-days-old. The laying hens were distributed according to a completely randomized design with 20 replicates and 20 birds per experimental unit. The treatments consisted of a diet supplemented with 70, 70 and 8 mg/kg of Zn, Mn and Cu; respectively, from inorganic sources (IM). The second treatment contained 40, 40 and 2.75 mg/kg of Zn, Mn and Cu, respectively from IM plus 30, 30 and 5.25 mg/kg of Zn, Mn and Cu; respectively, from AACM sources. Performance and reproductive organs development (oviduct and ovary weight), tibia weight, liver weight, egg output and body weight, and blood variables were evaluated. Data were compared by Student's t-test (P < 0.05). Laying hens fed AACM reached 35% of egg output two days earlier and presented heavier tibia bone than the IM group. Those hens also presented greater oviduct weight, greater hematocrit and greater serum concentration of total leukocytes, erythrocytes, eosinophils, monocytes and the hormones T4 and FSH, than the hens fed IM. The supplementation of AACM in laying hens' diets since one-day-old improves the productive performance from the beginning of egg output to peak production, which is justified by better development of bones and oviduct, hormone production and immune system support.

Transcriptome analyses to reveal the dynamic change mechanism of pigeon magnum during one egg-laying cycle

We analyzed the transcriptome of pigeon magnum in three stages (C1: pre-ovulation, C2: post-ovulation, C3: 5-6 days after ovulation) to elucidate the molecular and cellular events associated with morphological changes during the laying cycle. We observed that C1 was highly developed, apoptosis rate was highest in C2, and C3 attained the smallest size. Through RNA-sequencing, we obtained 54,764,938 (97.2%) high-quality clean reads that aligned to 20,767 genes. Gene expression profile analysis showed the greatest difference between C1 and C3; 3966 differentially expressed genes (DEGs) were identified, of which 2250 genes were upregulated and 1716 genes were downregulated in C1. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that protein processing and transport activities were prominent in C1, and upregulated genes included those related to signal recognition particle (SRP), signal recognition particle receptor (SRPR), translocon, GRP78, RRBP1, TRAP, TRAM1, and OST. Egg white protein-related gene expression was highest, with OVALY being the most highly expressed. In C2, apoptosis-related gene expression was higher than in C1, and fatty acid metabolism was active, which may be correlated with magnum tissue regression. Collagen- and laminin-related gene expression was prominent in C1 and C3, indicating roles in egg white protein generation and magnum reconstruction. PR gene expression was highest and exhibited drastic change in the three groups, indicating that PR and its regulation may be involved in changes in magnum morphology and function. Through the identification and functional analysis of DEGs and other crucial genes, this may contribute to understand the egg white protein production, magnum tissue regression, and magnum regeneration mechanisms.

Transcriptome analysis of the uterus of hens laying eggs differing in cuticle deposition

Background

Avian eggs have a proteinaceous cuticle. The quantity of cuticle varies and the deposition of a good cuticle in the uterus (Shell-gland) prevents transmission of bacteria to the egg contents.

Results

To understand cuticle deposition, uterus transcriptomes were compared between hens with i) naturally good and poor cuticle and, ii) where manipulation of the hypothalamo-pituitary-gonadal-oviduct axis produced eggs with or without cuticle. The highest expressed genes encoded eggshell matrix and cuticle proteins, e.g. MEPE (OC-116), BPIFB3 (OVX-36), RARRES1 (OVX-32), WAP (OVX-25), and genes for mitochondrial oxidative phosphorylation, active transport and energy metabolism. Expression of a number of these genes differed between hens laying eggs with or without cuticle. There was also a high expression of clock genes. PER2, CRY2, CRY1, CLOCK and BMAL1 were differentially expressed when cuticle deposition was prevented, and they also changed throughout the egg formation cycle. This suggests an endogenous clock in the uterus may be a component of cuticle deposition control. Cuticle proteins are glycosylated and glycosaminoglycan binding genes had a lower expression when cuticle proteins were deposited on the egg. The immediate early genes, JUN and FOS, were expressed less when the cuticle had not been deposited and changed over the egg formation cycle, suggesting they are important in oviposition and cuticle deposition. The uterus transcriptome of hens with good and poor cuticle deposition did not differ.

Conclusions

We have gained insights into the factors that can affect the production of the cuticle especially clock genes and immediate early genes. We have demonstrated that these genes change their expression over the period of eggshell formation supporting their importance. The lack of differences in expression between the uterus of hens laying eggs with the best and worse cuticle suggest the genetic basis of the trait may lie outside the oviduct.

Response of the chicken ovary to GH treatment during a pause in laying induced by fasting

This study was undertaken to examine the effect of GH treatment during a pause in laying on (1) ovarian follicle formation, growth (folliculogenesis), and atresia; (2) follicle cell proliferation and apoptosis; and (3) mRNA expression of selected yolk-specific proteins in the chicken liver. A pause in egg laying was induced by food deprivation for 5 d, followed by feeding every other day, and then feeding daily from day 10 onward. Birds were divided into 3 groups: control (n = 18) fed ad libitum, subjected to a pause in laying (n = 18), and subjected to a pause in laying and injected every day with 200 μg/kg BW of chicken GH (chGH; n = 18). The liver, ovarian stroma, and follicles were isolated from the hens of each group on days 6 (ovary regression), 13 (ovary recrudescence), and 17 or 20 (ovary rejuvenated) of the experiment. The results showed that injection of chGH during fasting (1) increased the number of follicles <1 mm and proliferating cell nuclear antigen (PCNA)-positive (proliferating) cells in these follicles; (2) attenuated the expression of PCNA and survivin mRNA in the white follicles and the activity of caspases 3, 8, and 9 in the stroma and white follicles; (3) intensified the atresia of yellow hierarchical follicles; and (4) deepened the effect of starvation on egg yolk gene expression concomitantly with considerably increased IGF-1 transcription levels in the liver (P < 0.05 to P < 0.001). Prolongation of chGH injections into the refeeding period did not exert pronounced effects on the examined parameters. In summary, the results provide evidence that GH promotes the formation and development of prehierarchical follicles in the hen ovary during a pause in laying by regulating cell proliferation and apoptosis. Alterations in cell proliferation- and apoptosis-related gene expression or enzyme activity in ovarian follicles as well as the expression of egg yolk proteins in the liver after chGH treatment strongly suggest that this hormone is involved in determining the rate of regression and rejuvenation of the chicken ovary during a pause in laying.

Transcriptome analysis reveals differentially expressed genes and pathways for oviduct development and defense in prelaying and laying hens

PROBLEM

The oviduct plays an indispensable role in the formation of eggs, especially the magnum and uterus. The identification of oviduct development in different stages will help to target candidate genes and pathways in regulation of albumen and eggshell formation, as well as defense mechanism in oviduct and egg.

METHODS

To identify the function differences and the molecular defense mechanism of the oviduct and egg, we performed transcriptome sequencing analysis of the magnum and uterus in 120-d-old and 300-d-old Lohmann layers, three birds in each group.

RESULTS

With fold changes (log2 ratio) ≥ 2 and false discovery rate (FDR) < 0.01, RNA-Seq revealed 1,040 genes expressed differentially in the magnum and 595 genes in the uterus. By combining GO enrichment and KEGG pathway analysis, it served to show that gene activities of the magnum and uterus in prelaying chickens were more likely to concentrate on growth and development, and after egg-laying, they were mainly inclined to enhance the substances transmembrane transport and secretion activities. We further characterized 1579 new genes, while only 803 of them were functionally annotated. A complex mixture of proteins related to defense was measured in this study. A subset of avian β-defensins (AvBDs) and ovodefensins (OvoDs), that is, AvBD12, AvBD11, AvBD10, OvoDA1, OvoDB1, OvoDA2, OvoDA3, and OvoDBβ, was detected to express in the magnum of laying hens at high levels.

CONCLUSION

Collectively, the identification and functional analysis of these differentially expressed genes (DEGs), as well as specific expression of avian defensins, may contribute to understand the development and defense mechanisms of oviduct and eggs.

Vaccine to fibroblast growth factor 23 peptides increases eggshell strength

Strategies that would increase eggshell quality could be of considerable value to egg producers. This research demonstrated the effective use of fibroblast growth factor 23 (FGF-23) peptide vaccines to increase eggshell quality of Single Comb White Leghorn laying hens (from 69 to 72 wk of age). Hens, fed a standard diet (containing 900 IU/kg vitamin D3), were intramuscularly injected (and boosted) with either a control vaccine (n = 14 hens) or one of 2 FGF-23 peptide vaccines (peptides NP1, GMNPPPYS; and NP7, YTSTERNSFH; n = 15 hens for each peptide). During peak antibody titer, eggs were collected for shell and internal quality analysis, hens were artificially inseminated, and the hatchability of fertilized eggs was determined. Laying hens vaccinated with either FGF-23 peptide NP1 or NP7 had increased (P < 0.05) plasma phosphate level (mmol/L; NP1 = 1.74, NP7 = 1.76, control = 1.47), egg specific gravity (NP1 = 1.083, NP7 = 1.083, control = 1.079), and eggshell strength (g of force; NP1 = 4002, NP7 = 4157, control = 3102) when compared to control vaccinated hens. FGF-23 peptide NP1 vaccinated hens also had increased eggshell thickness (mm, P < 0.001), shell weight (g, P = 0.032), and shell index (% of whole egg, P = 0.023) when compared to control vaccinated hens. FGF-23 peptide NP7 vaccinated hens tended to have decreased eggshell weight (P = 0.064) when compared to control vaccinated hens. Hatchability of fertilized eggs was not affected in incubations 1 and 3, but tended to be decreased (P = 0.097) by FGF-23 peptide NP1 vaccination in incubation 2. In conclusion, vaccines to FGF-23 peptides increased eggshell quality of laying hens with minimal adverse effects on egg internal quality. The effect of FGF-23 peptide vaccination on hatchability remains to be clarified.

A Functional Mutation in KIAA1462 Promoter Decreases Glucocorticoid Receptor Affinity and Affects Egg-Laying Performance in Yangzhou Geese

The identification of genetic markers is valuable for improving the egg-laying performance in goose production. The single-nucleotide polymorphism (SNP) rs1714766362 in an intron of the goose KIAA1462 gene was found to be relevant to laying performance in our previous study. However, its function remains unclear. In this study, the full-length coding sequence of KIAA1462 gene was firstly characterized in Yangzhou geese. Q-PCR (Quantitative Real Time Polymerase Chain Reaction) results showed that KIAA1462 was highly expressed in the liver, ovary, and mature F1 follicles. For SNP rs1714766362, geese with the AA genotype showed better laying performance than the TT ones and exhibited a higher KIAA1462 expression level in the ovary. Gain- and loss-of function experiments in granulosa cells revealed that KIAA1462 affected the expression of the apoptosis marker gene caspase-3. Considering that rs1714766362 locates in an intron area, we compared the KIAA1462 promoter regions of AA and TT individuals and identified the SNP c.-413C>G (Genbank ss2137504176), which was completely linked to SNP rs1714766362. According to the transcription factor prediction results, the glucocorticoid receptor (GR) would bind to the SNP site containing the C but not the G allele. In this study, we proved this hypothesis by an electrophoretic mobility shift assay (EMSA). In summary, we identified a novel mutation in the promoter of KIAA1462 gene which can modulate GR binding affinity and affect the laying performance of geese.

Involvement of matrix metalloproteinases (MMP-2, -7, -9) and their tissue inhibitors (TIMP-2, -3) in the regression of chicken postovulatory follicles

The study was undertaken to examine mRNA expression and localization of selected matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), and the activity of MMPs in chicken postovulatory follicles (POFs) during their apoptotic regression. Apoptotic cells and apoptosis-related caspase expression and activity were examined as well. Chickens were sacrificed 2 h and 21 h after ovulation, and five POFs (POF1 to POF5) were isolated from the ovaries. It was found that the number of apoptotic cells (TUNEL-positive) increased along with follicle regression. The relative expression (RQ) of caspase-2, -3, -8 and -9 mRNA increased (P < 0.05) in POF5, while the activity of all examined caspases elevated gradually (approximately 80-150%) reaching the highest level in POF3, and then slowly decreased to the value noted in POF1 (P < 0.05 - P < 0.001). Real-time polymerase chain reaction revealed different expression of MMP-2, -7, -9 and TIMP-2 and -3 on mRNA levels, and activity assay showed the changes in activity of MMP-2 and -9 in the POFs. Regression of the follicles was accompanied predominantly by an increase in the relative expression of MMP-2, and a decrease in TIMP-2 and -3 mRNAs (P < 0.05 - P < 0.001). The activity levels of MMP-2 and -9 showed pronounced changes during the examined period. During follicle regression elevated activity of MMP-2 and -9 was found (P < 0.05 - P < 0.001). Immunohistochemistry demonstrated tissue- and follicle-dependent immunoreactivity of the examined members of the MMP system. In summary, the results showing the apoptotic regression-related changes as well as tissue-dependent differences in the expression of selected MMPs and TIMPs, and activity of MMP-2 and MMP-9, point to the significance that these molecules might participate in the complex orchestration of chicken POF regression.

Effect of growth hormone on steroid concentrations and mRNA expression of their receptor, and selected egg-specific protein genes in the chicken oviduct during pause in laying induced by fasting

This study was undertaken to examine the effect of growth hormone (GH) treatment during pause in laying on (1) the concentration of steroids in blood plasma and oviduct tissues, (2) the expression of mRNA of steroid receptors, and (3) the mRNA expression of selected egg-specific proteins in the chicken oviduct. A pause in egg laying was induced by food deprivation for 5 d, followed by feeding every other day, and then feeding daily from Day 10 onward. Birds were divided into three groups: control (n = 18) fed ad libitum, subjected to pause in laying (n = 18), and subjected to pause in laying and injected every day with 200 μg/kg BW of chicken GH (chGH; n = 18). The oviduct was isolated from hens of each group on Days 6 (when the oviduct was regressed), 13 (during oviduct recrudescence), and 17 or 20 (rejuvenated oviduct) of the experiment. Fasting caused a decrease in plasma concentrations of progesterone (P4), testosterone, and estradiol on Day 6 and a reduction in tissue concentrations of these steroids on Days 6 and 13. Fasting also caused an increased relative expression of estrogen receptor α and β (ERα, ERβ) and progesterone receptor (PR) in the magnum and shell gland on Day 6, increased ERα and PR in the magnum on Days 13 and 17 or 20, and increased androgen receptor (AR) mRNA in the magnum on Days 6 and 13 and in the shell gland on Day 13. A fasting-induced elevation in ovocalyxin-36 mRNA expression on Day 6 and a decrease in avidin mRNA on Days 6 and 13 and in ovocleidin-116 on Day 13 were also observed (P < 0.05 to P < 0.001). Administration of chGH abolished the fasting-induced decrease in the concentration of steroids in plasma and tissues. Furthermore, chGH enhanced the effect of fasting on mRNA expression of PR, ERα, and avidin in the magnum on Day 6, and ERα in the shell gland on Day 13. The gene expression of ovalbumin on Days 6 and 13, ovocalyxin-36 and ovocleidin-116 on Day 6 was decreased in chGH-treated chickens. In contrast, the expression of ovalbumin on Day 17 or 20 was increased (P < 0.05 to P < 0.001). The results obtained indicate that, by alterations in the concentration of steroid hormones and their receptor expression in the chicken oviduct, GH determines the rate of regression and rejuvenation of this organ during molting. Moreover, changes in the expression of selected egg proteins indicate that GH might be the regulator of the secretory activity of the hen oviduct.

Alterations in apoptotic markers and egg-specific protein gene expression in the chicken oviduct during pause in laying induced by tamoxifen

The aim of this study was to examine the cell apoptosis, gene expression and activity of caspases 2, 3, 8 and 9, and the mRNA expression of selected egg-specific proteins in the chicken oviduct during pause in egg laying induced by tamoxifen (TMX) treatment. The experiment was carried out on Hy-Line Brown laying hens. The control birds were treated subcutaneously with vehicle (ethanol) and the experimental ones with TMX at a dose of 6 mg/kg of body weight. Hens were treated daily until a pause in egg laying occurred and sacrificed on Day 7 of the experiment. Within the oviductal wall, the highest number of apoptotic cells (TUNEL-positive) was found in the luminal epithelium and the lowest in the stroma. The administration of TMX increased the percentage of apoptotic cells in the magnum, isthmus, and shell gland as well as immunoreactivity for caspases 3 and 9. Real-time PCR analysis revealed the segment-dependent mRNA expression of caspases 2, 3, 8 and 9. Treatment of hens with TMX elevated the level of caspase-2 transcript in the infundibulum, caspases 2, 3 and 8 in the isthmus, and caspase-9 in the shell gland (P < 0.05 - P < 0.001). As shown by fluorometric method TMX caused an increase in the activity of caspases 3 and 8 in the magnum, isthmus and shell gland, and the activity of caspases 2 and 9 in the isthmus and shell gland (P < 0.05 - P < 0.01). The expression of ovalbumin, avidin and ovocleidin-116 mRNAs was decreased (P < 0.05 - P < 0.001), ovocalyxin-36 mRNA level tended to increase, and ovocalyxin-32 expression was not affected by TMX. The results obtained indicate that caspases are involved in the chicken oviduct regression during a pause in laying induced by TMX, and estrogen is involved in the regulation of examined caspase expression and activity. The changes in mRNA transcript levels of some examined egg-specific proteins after TMX treatment suggest that there is a relationship between estrogen action and the expression of these genes.

Aquaporin 3 is regulated by estrogen in the chicken oviduct and is involved in progression of epithelial cell-derived ovarian carcinomas

Aquaporins (AQPs) are membrane proteins that passively deliver water across the plasma membrane to play an important role in maintaining cell shape. Members of the AQP family are distributed in most of the tissues in the human body and perform a variety of functions based on the water homeostasis suitable for each organ. However, there is little known about the expression and regulation of AQP family members in chickens. Therefore, we determined the expression of AQPs in various tissues of chickens. Among 13 isotypes, AQP3 was highly expressed in the chicken oviduct. Expression of AQP3 messenger RNA (mRNA) increased in the magnum (P < 0.001) and isthmus (P < 0.001) of chick oviducts treated with diethylstilbestrol. Consistent with these results, the localization of AQP3 was detected in the glandular and luminal epithelia of the magnum and isthmus of oviducts of diethylstilbestrol-treated chicks. In addition, the pattern of expression of AQP3 changed in an estrogen-dependent manner during the molting period. During the regenerative period of the oviduct after molting, expression of AQP3 mRNA increased coordinately with increasing concentrations of estradiol (P < 0.001), whereas expression of AQP3 mRNA decreased as concentrations of estradiol in plasma decreased in response to induced molting (P < 0.001). Also, expression of the AQP3 increased (P < 0.001) in cancerous ovaries of laying hens. In conclusion, AQP3 does not simply function to transport water into and out of cells but also appears to be closely involved in development of the chicken oviduct, which is regulated by estrogens. Furthermore, our results suggest AQP3 as a new diagnostic for early detection and treatment of epithelial cell-derived ovarian carcinomas.

Direct antiapoptotic effects of growth hormone are mediated by PI3K/Akt pathway in the chicken bursa of Fabricius

Growth hormone (GH) is expressed in several extra-pituitary tissues, including the primary and secondary lymphoid organs of the immune system. In birds, GH mRNA and protein expression show a specific developmental distribution pattern in the bursa of Fabricius (BF), particularly in epithelial and B cells. Changes in the bursal concentration and distribution of locally produced GH during ontogeny suggest it is involved in B cell differentiation and maturation, as well as in a functional survival role in this organ, which may be mediated by paracrine/autocrine mechanisms. Here, we analyzed the anti-apoptotic effect of GH in BF and the intracellular signaling pathways involved in this activity. Also, we studied if this effect was exerted directly by GH or mediated indirectly by IGF-I. Bursal cell cultures showed an important loss of their viability after 4h of incubation and a significant increase in apoptosis. However, treatment with 10nM GH or 40 nM IGF-I significantly increased B cell viability (16.7 ± 0.67% and 13.4 ± 1.12%, respectively) when compared with the untreated controls. In addition, the presence of apoptotic bodies (TUNEL) dramatically decreased (5.5-fold) after GH and IGF-I treatments, whereas co-incubation with anti-GH or anti-IGF-I, respectively, blocked their anti-apoptotic effect. Likewise, both GH and IGF-I significantly inhibited caspase-3 activity (by 40 ± 2.0%) in these cultures. However, the use of anti-IGF-I could not reverse the GH anti-apoptotic effects, thus indicating that these were exerted directly. The addition of 100 nM wortmannin (a PI3K/Akt inhibitor) blocked the GH protective effects. Also, GH stimulated (3-fold) the phosphorylation of Akt in bursal cells, and adding wortmannin or an anti-GH antibody inhibited this effect. Furthermore, GH was capable to stimulate (7-fold) the expression of Bcl-2. Taken together, these results indicate that the direct anti-apoptotic activity of GH observed in the chicken bursal B cell cultures might be mediated through the PI3K/Akt pathway.

Growth hormone production and role in the reproductive system of female chicken

The expression and role of growth hormone (GH) in the reproductive system of mammals is rather well established. In birds the limited information thus far available suggests that GH is an endocrine or paracrine/autocrine regulator of ovarian and oviductal functions too. GH and its receptors are expressed in all compartments of the ovary and oviduct and change accordingly to physiological state. The intra-ovarian role of GH likely includes the regulation of steroidogenesis, cell proliferation and apoptosis, the modulation of LH action and the synthesis of IGFs (insulin-like growth factors). In the oviduct, GH is also involved in the regulation of oviduct-specific protein expression. The present study provides a review of current knowledge on the presence and action of GH in the female reproduction, in which it is likely that act in endocrine, autocrine or paracrine mechanisms.