Counter-current transfer in reproductive biology

Intranasal nanoparticulate delivery systems for neurodegenerative disorders: a review

Neurodegenerative diseases are a significant cause of mortality worldwide, and the blood-brain barrier (BBB) poses a significant challenge for drug delivery. An intranasal route is a prominent approach among the various methods to bypass the BBB. There are different pathways involved in intranasal drug delivery. The drawbacks of this method include mucociliary clearance, enzymatic degradation and poor drug permeation. Novel nanoformulations and intranasal drug-delivery devices offer promising solutions to overcome these challenges. Nanoformulations include polymeric nanoparticles, lipid-based nanoparticles, microspheres, liposomes and noisomes. Additionally, intranasal devices could be utilized to enhance drug-delivery efficacy. Therefore, intranasal drug-delivery systems show potential for treating neurodegenerative diseases through trigeminal or olfactory pathways, which can significantly improve patient outcomes.

An interactive analysis of the mouse oviductal miRNA profiles

MicroRNAs are small non-coding molecules that control several cellular functions and act as negative post-transcriptional regulators of the mRNA. While their implication in several biological functions is already known, an important role as regulators of different physiological and pathological processes in fertilization and embryo development is currently emerging. Indeed, miRNAs have been found in the oviductal fluid packaged within the extracellular vesicles, which might act as natural nanoshuttles by transporting lipids, proteins, RNA molecules and miRNAs from the oviduct to the gametes or embryos. Here, an exhaustive bibliography search was carried out, followed by the construction of a computational model based on the networks theory in an attempt to recreate and elucidate the pathways potentially activated by the oviductal miRNA. The omics data published to date were gathered to create the Oviductal MiRNome, in which the miRNA target genes and their interactions are represented by using stringApp and the Network analyzer from Cytoscape 3.7.2. Then, the hyperlinked nodes were identified to investigate the pathways in which they are involved using the gene ontology enrichment analysis. To study the phenotypical effects after the removal of key genes on the reproductive system and embryo, knockout mouse lines for every protein-coding gene were investigated by using the International Mouse Phenotyping Consortium database. The creation of the Oviductal MiRNome revealed the presence of important genes and their interactions within the network. The functional enrichment analysis revealed that the hyperlinked nodes are involved in fundamental cellular functions, both structural and regulatory/signaling, suggesting their implication in fertilization and early embryo development. This fact was as well evidenced by the effects of the gene deletion in KO mice on the reproductive system and embryo development. The present study highlights the importance of studying the miRNA profiles and their enormous potential as tools to improve the assisted reproductive techniques currently used in human and animal reproduction.

Temperature sensitivity of DNA double-strand break repair underpins heat-induced meiotic failure in mouse spermatogenesis

Mammalian spermatogenesis is a heat-vulnerable process that occurs at low temperatures, and elevated testicular temperatures cause male infertility. However, the current reliance on in vivo assays limits their potential to detail temperature dependence and destructive processes. Using ex vivo cultures of mouse testis explants at different controlled temperatures, we found that spermatogenesis failed at multiple steps, showing sharp temperature dependencies. At 38 °C (body core temperature), meiotic prophase I is damaged, showing increased DNA double-strand breaks (DSBs) and compromised DSB repair. Such damaged spermatocytes cause asynapsis between homologous chromosomes and are eliminated by apoptosis at the meiotic checkpoint. At 37 °C, some spermatocytes survive to the late pachytene stage, retaining high levels of unrepaired DSBs but do not complete meiosis with compromised crossover formation. These findings provide insight into the mechanisms and significance of heat vulnerability in mammalian spermatogenesis.

Progesterone-Induced Sperm Release from the Oviduct Sperm Reservoir

In mammalian females, after sperm are deposited in the reproductive tract, a fraction of sperm migrates to the lower oviduct (isthmus) and forms a sperm storage site known as the functional sperm reservoir. The interactions between sperm membrane proteins and oviduct epithelial cells facilitate sperm binding to the oviductal epithelium and retention in the reservoir. Sperm are bound by glycans that contain specific motifs present on isthmic epithelial cells. Capacitated sperm are released from the reservoir and travel further in the oviduct to the ampulla where fertilization occurs. For decades, researchers have been studying the molecules and mechanisms of sperm release from the oviductal sperm reservoir. However, it is still not clear if the release of sperm is triggered by changes in sperm, oviduct cells, oviduct fluid, or a combination of these. While there is a possibility that more than one of these events are involved in the release of sperm from the reservoir, one activator of sperm release has the largest accumulation of supporting evidence. This mechanism involves the steroid hormone, progesterone, as a signal that induces the release of sperm from the reservoir. This review gathers and synthesizes evidence for the role of progesterone in inducing sperm release from the oviduct functional sperm reservoir.

Pre-Treatment of Swine Oviductal Epithelial Cells with Progesterone Increases the Sperm Fertilizing Ability in an IVF Model

Mammalian spermatozoa are infertile immediately after ejaculation and need to undergo a functional modification, called capacitation, in order to acquire their fertilizing ability. Since oviductal epithelial cells (SOECs) and progesterone (P4) are two major modulators of capacitation, here we investigated their impact on sperm functionality by using an IVF swine model. To that, we treated SOECs with P4 at 10, 100, and 1000 ng/mL before the coincubation with spermatozoa, thus finding that P4 at 100 ng/mL does not interfere with the cytoskeleton dynamics nor the cells’ doubling time, but it promotes the sperm capacitation by increasing the number of spermatozoa per polyspermic oocyte (p < 0.05). Moreover, we found that SOECs pre-treatment with P4 100 ng/mL is able to promote an increase in the sperm fertilizing ability, without needing the hormone addition at the time of fertilization. Our results are probably due to the downregulation in the expression of OVGP1, SPP1 and DMBT1 genes, confirming an increase in the dynamism of our system compared to the classic IVF protocols. The results obtained are intended to contribute to the development of more physiological and efficient IVF systems.

Effects of Heat Stress on Follicular Physiology in Dairy Cows

Simple Summary

Environmentally induced hyperthermia, also called heat stress (HS), compromises reproductive physiology in mammals. The number of oocytes is fixed after birth and they are stored in the ovary in a quiescent state (at the stage of the first meiotic prophase) in primordial follicles. There is evidence that HS alters the oocyte quality, the dynamics of follicular growth and ovulation. The dairy cow, submitted to the metabolic stress of high milk production, is a good model for studying the effects of HS on ovarian function. The aim of this review is to describe the influence of HS during the stages of follicular development in dairy cattle, from the activation of primordial follicles to ovulation. Some clinical aspects are also considered.

Abstract

Follicular organization starts during mid-to-late fetal life with the formation of primordial follicles. The bilateral interplay between the oocyte and adjoining somatic cells during follicular growth and ovulation may be sensitive to heat stress (HS). Mechanisms giving rise to pre-ovulatory temperature gradients across reproductive tissues are mostly regulated by the pre-ovulatory follicle, and because the cooling of the gonads and genital tract depends on a counter-current transfer system of heat, HS may be considered a major factor impairing ovulation, fertilization and early embryo development. There is evidence of a long-lasting influence of HS on oogenesis and final follicular maturation. Follicular stages that are susceptible to HS have not been precisely determined. Therefore, the aim of this review was to describe the influence of HS during the staged follicular development in dairy cattle, from the activation of primordial follicles to ovulation. Some clinical prospects are also considered.

Peritoneal fluid progesterone and progesterone resistance in superficial endometriosis lesions

Peritoneal fluid in ovulatory women is an ovarian exudate with higher estrogen and progesterone concentrations than in plasma. In the follicular phase, progesterone concentrations are as high as plasma concentrations in the luteal phase. After ovulation, estrogen and progesterone concentrations in the peritoneal fluid are 5-10 times higher than in plasma, both in women with and without endometriosis. The histologically proliferative aspect without secretory changes of most superficial subtle lesions is not compatible with the progesterone concentrations in the peritoneal fluid. Therefore, we have to postulate a strong progesterone resistance in these lesions. The mechanism is unclear and might be a peritoneal fluid effect in women with predisposing defects in the endometrium, or isolated endometrial glands with progesterone resistance, or subtle lesions originating from the basal endometrium: the latter hypothesis is attractive since in basal endometrium progesterone does not induce secretory changes while progesterone withdrawal, not occurring in peritoneal fluid, is required to resume mitotic activity and proliferation. Hormone concentrations in the peritoneal fluid are an important factor in understanding the medical therapy of endometriosis. The effect of oestro-progestin therapy on superficial endometriosis lesions seems to be a consequence of the decreased estrogen concentrations rather than a direct progestin effect. In conclusion, the peritoneal fluid, being a secretion product of the ovarian follicule, deserves more attention in the pathophysiology and treatment of endometriosis.

Nanotechnologies for intranasal drug delivery: an update of literature

Scientific research has focused its attention on finding an alternative route to systemic oral and parenteral administration, to overcome their usual drawbacks, such as hepatic first-pass which decreases drug bioavailability after oral administration, off-target effects, low patient compliance and low speed of onset of the pharmacological action in first-aid cases. Innovative drug delivery systems (DDS), mainly based on polymer and lipid biocompatible materials, have given a great prompt in this direction in the last years. The intranasal (IN) route of administration is a valid non-invasive alternative. It is highly suitable for self-administration, the drug quickly reaches the bloodstream, largely avoiding the first pass effect, and can also reach directly the brain bypassing BBB. Association of IN route with DDS can thus become a winning strategy for the controlled delivery of drugs, especially when a very quick effect is desired or needed. This review aims at analyzing the scientific literature regarding IN-DDS and their different ways of administration (systemic, topical, pulmonary, nose-to-brain). In particular, attention was devoted to polymer- and lipid-based micro- and nanocarriers, being the topic of most published articles in the last decade, but the whole plethora of colloidal DDS investigated in recent years for IN administration was presented.

Sperm migration, selection, survival, and fertilizing ability in the mammalian oviduct†

In vitro fertilization (IVF) gives rise to embryos in a number of mammalian species and is currently widely used for assisted reproduction in humans and for genetic purposes in cattle. However, the rate of polyspermy is generally higher in vitro than in vivo and IVF remains ineffective in some domestic species like pigs and horses, highlighting the importance of the female reproductive tract for gamete quality and fertilization. In this review, the way the female environment modulates sperm selective migration, survival, and acquisition of fertilizing ability in the oviduct is being considered under six aspects: (1) the utero-tubal junction that selects a sperm sub-population entering the oviduct; (2) the presence of sperm binding sites on luminal epithelial cells in the oviduct, which prolong sperm viability and plays a role in limiting polyspermic fertilization; (3) the contractions of the oviduct, which promote sperm migration toward the site of fertilization in the ampulla; (4) the regions of the oviduct, which play different roles in regulating sperm physiology and interactions with oviduct epithelial cells; (5) the time of ovulation, and (6) the steroid hormonal environment which regulates sperm release from the luminal epithelial cells and facilitates capacitation in a finely orchestrated manner.

Testicular shape, scrotal skin thickness and testicular artery blood flow changes in bulls of different ages

The aim of this study was to compare the biometric testicular characteristics, skin thickness and haemodynamics of the testicular artery of 12- and 24-month-old bulls using Doppler ultrasonography, the study was conducted using 48 indicus-taurus animals. The scrotal circumference (SC) and biometry characteristics of the bulls were measured to calculate the testicular volume. Doppler ultrasonography was used to obtain the haemodynamic values of the testicular artery. The skin thickness and volume were lower (p<.01) in the younger bulls (12 months:4.68 ± 0.68 mm; 168.76 ± 47.96 cm³ ) versus 24 months (5.05 ± 0.89; 499.73 ± 129.24 cm³ ) animals (p<.01). During diastole, mean velocity was lower in the 12 months (7.98 ± 3.83) than in the 24 months (11.37 ± 4.15) animals (p <.05). The 12-month-old animals had higher pulsatility and resistivity indices (0.49 ± 0.02; 0.51 ± 0.20) compared to the 24-month-old animals (0.32 ± 0.16; 0.40 ± 0.15) (p < .05). The final testicular end velocity was lower in animals with long/moderate-shaped (L/M) (7.31 ± 2.91) than in those moderate/oval-shaped (M/O) (11.48 ± 3.88) testicles (p < .05). Animals with L/M testes presented higher pulsatility values and resistivity indices (0.51 ± 0.05; 0.55 ± 0.04) compared to animals with M/O shape (0.29 ± 0.20; 0.36 ± 0.15). We showed that the blood flow of the supra testicular artery between the two evaluated ages differed, and that 24-month-old bulls presented better thermoregulation capacity. Animals with a long/moderate testicular format presented a greater vascular resistance, which was imposed on the blood flow due to the anatomical differences in the testicular artery, resulting in lower velocity, and indicating better heat dissipation in this format.

Thermal Mechanisms Preventing or Favoring Multiple Ovulations in Dairy Cattle

Simple Summary

While cows are usually monovular, the incidence of dizygous twin births has recently increased considerably alongside increasing milk production. Genetic progress and improvements in nutrition and management practices have led to a continuous increase in milk yield and thus also to multiple ovulations and twin pregnancies. Twin pregnancies are undesirable as they seriously compromise the welfare of the cow and herd economy. A better understanding of the processes associated with multiple ovulations should help to reduce rates of twinning. During the stages of the sexual cycle, temperature gradients are established within the ovary and throughout the genital tract. Pre-ovulatory local cooling of the reproductive system favors male and female gamete maturation and subsequent fertilization. In fact, thermal mechanisms may prevent or favor multiple ovulations and thus twinning. The purpose of this review was to update this topic.

Abstract

While cows are predominantly monovular, over the past 30 years the incidence of multiple ovulations and thus twinning has increased considerably alongside milk production. Multiple pregnancies are not desirable as they negatively affect the health of cows and the herd economy. Although causal mechanisms associated with multiple ovulations have been extensively revised, the process of multiple ovulations is not well understood. Recent studies on the thermal biology of the reproductive system have shown how thermal mechanisms may prevent or favor multiple ovulations. This review focuses on this relationship between thermal dynamics and multiple pregnancies. Cooling of the pre-ovulatory follicle is able to regulate ovulation. In effect, pre-ovulatory local cooling of the female reproductive system favors male and female gamete maturation and promotes fertilization. Thermal stress is proposed here as a model of stress. Periods of high ambient temperature affect the processes of pre-ovulatory follicular cooling and multiple ovulations. While the ratio between unilateral and bilateral multiple pregnancies is normally close to one, under heat stress conditions, this ratio may be 1.4 favoring unilateral multiple pregnancies. A ratio approaching unity is here proposed as an indicator of cow wellbeing.

Ovarian odorant-like biomolecules in promoting chemotaxis behavior of spermatozoa olfactory receptors during migration, maturation, and fertilization

Background

Studies have shown that olfactory receptor genes are the largest in the human genome, which are significantly expressed in olfactory and non-olfactory tissues such as the reproductive systems where they perform many important biological functions.

Main body

There is growing evidence that bioactive metabolites from the ovary, follicular fluid, and other parts of the female reproductive tract signal the sperm through a series of signal transduction cascades that regulate sperm migration, maturation, and fertilization processes. Several studies have highlighted the role of G-protein-coupled receptors in these cellular processes. Thus, we aimed to summarize the existing evidence describing the physiological role of most prominent exogenous and endogenous biomolecules found in the female reproductive organ in enhancing the chemotaxis behavior of spermatozoa during migration, maturation, and fertilization and also to elucidate the pathological implications of its dysfunctions and the clinical significance in human fertility.

Short conclusion

In the future, drugs and molecules can be designed to activate these receptors on sperm to facilitate fertility among infertile couples and use as contraceptives.

Boar seminal plasma: current insights on its potential role for assisted reproductive technologies in swine

Seminal plasma (SP) supports not only sperm function but also the ability of spermatozoa to withstand biotechnological procedures as artificial insemination, freezing or sex sorting. Moreover, evidence has been provided that SP contains identifiable molecules which can act as fertility biomarkers, and even improve the output of assisted reproductive technologies by acting as modulators of endometrial and embryonic changes of gene expression, thus affecting embryo development and fertility beyond the sperm horizon. In this overview, we discuss current knowledge of the composition of SP, mainly proteins and cytokines, and their influence on semen basic procedures, such as liquid storage or cryopreservation. The role of SP as modulator of endometrial and embryonic molecular changes that lead to successful pregnancy will also be discussed.

Temperature gradients in the mammalian ovary and genital tract: A clinical perspective

Temperature within mammalian reproductive tissues is noted to be a key component of fertility, and significant gradients in temperature can be demonstrated deep within the abdomen shortly before ovulation. Indeed, in the absence of such gradients in the ovary and genital tract, the processes of ovulation and fertilisation are severely compromised. This review aims to assess literature produced during the last five decades regarding temperature gradients in the mammalian ovary and genital tract. A large body of observations derived from rabbits, women, pigs and cattle is summarised in tabular form, ovarian follicular values being as much as 2.5 °C or more cooler than neighbouring ovarian tissues or deep rectal temperature. We highlight recent works demonstrating a positive correlation between pre-ovulatory follicular cooling and pregnancy. Understanding the significance of follicular cooling should help us (a) explain why so many potential pregnancies fail in vivo as in vitro and (b) inspire ways for improving the processes of fertilisation and establishment of a full-term pregnancy. Based on our findings in domestic animals, and most recently in cows whose Graafian follicles are comparable in size and timing of response to the LH peak with human follicles, we wish to encourage IVF and fertility preservation clinics to take advantage of this work. By so doing, the incidence of full-term pregnancies in women should be improved.

Evolutionary sequences in mammalian reproductive biology

Broad biological aspects and accepted evolutionary sequences may offer useful guidance towards a comprehensive explanation of the function of mammalian ovaries and oviducts and their vital contribution to the events of fertilization. Cooling of the preovulatory follicles before ovulation may well have its roots in the primitive stages of external fertilization in which aggregates of oocytes are shed into freshwater.

Local cooling of the ovary and its implications for heat stress effects on reproduction

The effects of season on the fertility of the dairy cow added to the metabolic stress of milk production are well known. We here present lactating dairy cows as a comparative model of this problem. This review examines the results of recent studies that have highlighted heat stress (HS) effects on pre-ovulatory follicles. From these studies, we draw information regarding the mechanisms giving rise to temperature gradients across reproductive tissues. Our review is completed by a discussion of approaches designed to reduce the negative effects of HS based on cooling strategies implemented before ovulation at or around estrus.

Abortion in dairy cattle with advanced twin pregnancies: Incidence and timing

This study examines incidences and timing of abortion in Holstein Friesian dairy cows with advanced twin pregnancies in north-eastern Spain. The study population consisted of 1,194 twin pregnancies in two herds recorded from 2010 to 2015: 522 bilateral and 672 unilateral. The presence of live twins was determined by transrectal ultrasonography between 55 and 61 days post-AI and pregnancy confirmed 60 days later. Abortion was recorded in 278 (23.3%) cows before Day 260 of pregnancy: 7 (1.3%) in bilateral and 271 (40.3%) in unilateral twin pregnancies. Using binary logistic regression procedures the following were excluded as risk factors for abortion: herd, year, heat stress (temperature-humidity index values >72), lactation number and right versus left side for unilateral twins. Based on odds ratios, cows carrying unilateral twins were 49.9 (right unilateral twins) and 49.3 (left unilateral twins) times more likely to suffer abortion than cows with bilateral twins. The average time of abortion for unilateral twins was 173 ± 32 days and ranged from 135 to 249 days, 43% of abortions occurring between 135 and 154 days of gestation. The authors suggest prevention or reduction of unilateral twin pregnancies by follicular puncture and drainage of subordinate follicles at AI or manual rupture of the amniotic vesicle of one of the two twins at the time of pregnancy diagnosis.

Do differences in the endometrial transcriptome between uterine horns ipsilateral and contralateral to the corpus luteum influence conceptus growth to day 14 in cattle?

Embryo transfer to the uterine horn contralateral to the ovary containing the corpus luteum (CL) negatively impacts pregnancy establishment in cattle. Our aim was to compare the transcriptome and ability of the ipsilateral and contralateral uterine horns to support preimplantation conceptus survival and growth to day 14. In experiment 1, endometrial samples from both horns were collected from synchronized heifers slaughtered on day 5, 7, 13, or 16 post-estrus (n = 5 per time) and subjected to RNA sequencing. In experiment 2, 10 day 7 in vitro produced blastocysts were transferred into the uterine horn ipsilateral (n = 9) or contralateral to the CL (n = 8) or into both horns (i.e., bilateral, n = 9) of synchronized recipient heifers. Reproductive tracts were recovered at slaughter on day 14, and the number and dimensions of recovered conceptuses were recorded for each horn. A total of 217, 54, 14, and 18 differentially expressed genes (>2-fold change, FDR P < 0.05) were detected between ipsilateral and contralateral horns on days 5, 7, 13, and 16, respectively, with signaling pathways regulating pluripotency of stem cells, ErbB signaling pathway, and mTOR signaling pathway amongst the top canonical pathways. Site of embryo transfer did not affect recovery rate (48.0%, 168/350) or length of conceptuses (mean ± SE 2.85 ± 0.27 mm). Although differences in gene expression exist between the endometrium of uterine horns ipsilateral and contralateral to the CL in cattle, they do not impact conceptus survival or length between day 7 and 14.

Release of Porcine Sperm from Oviduct Cells is Stimulated by Progesterone and Requires CatSper

Sperm storage in the female reproductive tract after mating and before ovulation is a reproductive strategy used by many species. When insemination and ovulation are poorly synchronized, the formation and maintenance of a functional sperm reservoir improves the possibility of fertilization. In mammals, the oviduct regulates sperm functions, such as Ca²⁺ influx and processes associated with sperm maturation, collectively known as capacitation. A fraction of the stored sperm is released by unknown mechanisms and moves to the site of fertilization. There is an empirical association between the hormonal milieu in the oviduct and sperm detachment; therefore, we tested directly the ability of progesterone to induce sperm release from oviduct cell aggregates. Sperm were allowed to bind to oviduct cells or an immobilized oviduct glycan and then challenged with progesterone, which stimulated the release of 48% of sperm from oviduct cells or 68% of sperm from an immobilized oviduct glycan. The effect of progesterone on sperm release was specific; pregnenolone and 17α-OH-progesterone did not affect sperm release. Ca²⁺ influx into sperm is associated with capacitation and development of hyperactivated motility. Progesterone increased sperm intracellular Ca²⁺, which was abrogated by blocking the sperm–specific Ca²⁺ channel CatSper with NNC 055-0396. NNC 055-0396 also blocked the progesterone-induced sperm release from oviduct cells or immobilized glycan. An inhibitor of the non-genomic progesterone receptor that activates CatSper similarly blocked sperm release. This is the first report indicating that release of sperm from the sperm reservoir is induced by progesterone action through CatSper channels.

Seminal Plasma Modifies the Transcriptional Pattern of the Endometrium and Advances Embryo Development in Pigs

Background: Seminal plasma (SP) promotes sperm survival and fertilizing capacity, and potentially affects embryo development, presumably via specific signaling pathways to the internal female genital tract.

Objectives: This study evaluated how heterologous SP, infused immediately before postcervical artificial insemination (AI) affected embryo development and the transcriptional pattern of the pig endometria containing embryos.

Materials and Methods: Postweaning estrus sows (n = 34) received 40-mL intrauterine infusions of either heterologous pooled SP or Beltsville Thawing Solution (BTS; control) 30 min before AI of semen extended to 10% of homologous SP. Embryos (all sows) and endometrium samples (3 sows/group) were removed during laparotomy 6 days after the infusion of SP or BTS to morphologically evaluate the embryos to determine their developmental stage and to analyze the endometrial transcriptome using microarrays (PORGENE 1.0 ST GeneChip array, Affymetrix) followed by qPCR for further validation.

Results: Embryo viability was equal between the groups (~93%), but embryo development was significantly (P < 0.05) more advanced in the SP-treated group compared to control. A total of 1,604 endometrium transcripts were differentially expressed in the SP group compared to the control group. An enrichment analysis showed an overrepresentation of genes and pathways associated with the immune response, cytokine signaling, cell cycle, cell adhesion, and hormone response, among others.

Conclusions: SP infusions prior to AI positively impacted the preimplantation embryo development and altered the expression of the endometrial genes and pathways potentially involved in embryo development.

Nasal Drug Delivery of Anticancer Drugs for the Treatment of Glioblastoma: Preclinical and Clinical Trials

Glioblastoma (GBM) is the most lethal form of brain tumor, being characterized by the rapid growth and invasion of the surrounding tissue. The current standard treatment for glioblastoma is surgery, followed by radiotherapy and concurrent chemotherapy, typically with temozolomide. Although extensive research has been carried out over the past years to develop a more effective therapeutic strategy for the treatment of GBM, efforts have not provided major improvements in terms of the overall survival of patients. Consequently, new therapeutic approaches are urgently needed. Overcoming the blood–brain barrier (BBB) is a major challenge in the development of therapies for central nervous system (CNS) disorders. In this context, the intranasal route of drug administration has been proposed as a non-invasive alternative route for directly targeting the CNS. This route of drug administration bypasses the BBB and reduces the systemic side effects. Recently, several formulations have been developed for further enhancing nose-to-brain transport, mainly with the use of nano-sized and nanostructured drug delivery systems. The focus of this review is to provide an overview of the strategies that have been developed for delivering anticancer compounds for the treatment of GBM while using nasal administration. In particular, the specific properties of nanomedicines proposed for nose-to-brain delivery will be critically evaluated. The preclinical and clinical data considered supporting the idea that nasal delivery of anticancer drugs may represent a breakthrough advancement in the fight against GBM.

Equine chorionic gonadotropin increases estradiol levels in the bovine oviduct and drives the transcription of genes related to fertilization in superstimulated cows

In the bovine oviduct, estradiol (E2) stimulates secretion and cell proliferation, whereas progesterone (P4) suppresses them. In this study, we have evaluated the effect of two superstimulatory protocols (follicle-stimulating hormone [FSH] or FSH combined with equine chorionic gonadotropin [eCG]) on the oviductal levels of E2 and P4 and its outcome on oviductal cells. Compared with the control group (a single pre-ovulatory follicle), we have observed that the cows submitted to FSH/eCG treatment showed a higher concentration of E2 in the oviduct tissue, together with a higher abundance of messenger RNA encoding steroid receptors (ESR1 and progesterone receptor), and genes linked to gamete interactions and regulation of polyspermy (oviduct-specific glycoprotein 1, heat-shock protein family A member 5, α-l-fucosidase 1 [FUCA1], and FUCA2) in the infundibulum and ampulla segments of the oviduct. However, we did not observe any modulation of gene expression in the isthmus segment. Even though the FSH protocol upregulated some of the genes analyzed, we may infer that the steady effect of FSH combined with eCG on oviduct regulation might benefit fertilization and may potentially increase pregnancy rates.

Relative effects of location relative to the corpus luteum and lactation on the transcriptome of the bovine oviduct epithelium

Background

Lactation and associated metabolic stresses during the post-partum period have been shown to impair fertility in dairy cows. The oviduct plays key roles in embryo development and the establishment of pregnancy in cattle. The aim of this study was to investigate the effects of lactation and location relative to the corpus luteum (CL) on the transcriptome of the bovine oviduct epithelium.

Results

An original animal model was used. At 60 days post-partum, Holstein lactating (n = 4) and non-lactating (i.e. never milked after calving; n = 5) cows, as well as control nulliparous heifers (n = 5), were slaughtered on Day 3 following induced estrus, and epithelial samples from the oviductal ampulla and isthmus ipsilateral and contralateral to the corpus luteum (CL) were recovered for RNA sequencing. In the oviduct ipsilateral to the CL, differentially expressed genes (DEGs) were identified between heifers compared with both postpartum cow groups. However, only 15 DEGs were identified between post-partum lactating and non-lactating cows in the ipsilateral isthmus and none were identified in the ipsilateral ampulla. In contrast, 192 and 2583 DEGs were identified between ipsilateral and contralateral ampulla and isthmus, respectively. In both regions, more DEGs were identified between ipsilateral and contralateral oviducts in non-lactating cows and heifers than in lactating cows. Functional annotation of the DEGs associated with comparisons between metabolic groups highlighted a number of over-represented biological functions and cell pathways including immune response and cholesterol/steroid biosynthesis.

Conclusions

Gene expression in the oviduct epithelium, particularly in the isthmus, was more affected by the location relative to the CL than by lactation at Day 3 post-estrus. Furthermore, the effect of the proximity to the CL was modulated by the metabolic status of the cow.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5616-2) contains supplementary material, which is available to authorized users.

Seminal plasma modulates the immune-cytokine network in the porcine uterine tissue and pre-ovulatory follicles

Evidence is emerging that the interaction between male seminal fluid and female tissues promotes fertility, pregnancy, and health of offspring. This includes the acceleration of ovulation in a species known as a spontaneous ovulator, the domestic pig. Earlier studies revealed that seminal plasma acts by a local mechanism in the female pig. The aim of the present study was to examine local short-term and mid-term effects of seminal plasma (SP) on mRNA expression of immunoregulatory genes and transcripts associated with follicle- and oocyte maturation. In the porcine animal model, effects on mRNA expression in the female tract and preovulatory follicles were examined. SP suppressed mRNA expression of Prostaglandin-Endoperoxide Synthase 2 (PTGS2) ipsilateral to the infused uterine horn which was associated with a lower presence of immune cells in the uterine epithelium and lower PTGS2 immunoreaction. Depending on the sampling time (2 h vs. 17 h) and hormonal status, SP altered significant correlative relations of mRNA expression between PTGS2 and the transcripts Tumor Necrosis Factor Alpha, Tumor Necrosis Factor Alpha-Induced Protein 6 and Pentraxin 3 in uterus, granulosa and cumulus cells. A modulatory effect of SP on the oocyte gene network comprising eight oocyte transcripts was observed: uterine exposure to SP induced positive correlations (r >0.08, p<0.05) of maturation promoting factors among each other and with cumulus cells on the side of the treated horn. In conclusion, SP orchestrates the gene network regulating the bidirectional communication between oocytes and surrounding somatic cells. The modulation of the immune-cytokine network of the female reproductive system could contribute to the previously reported SP-induced acceleration of ovulation in the porcine species.

Thermosensitive hydrogels a versatile concept adapted to vaginal drug delivery

Vaginal drug delivery represents an attractive strategy for local and systemic delivery of drugs otherwise poorly absorbed after oral administration. The rather dense vascular network, mucus permeability and the physiological phenomenon of the uterine first-pass effect can all be exploited for therapeutic benefit. However, several physiological factors such as an acidic pH, constant secretion, and turnover of mucus as well as varying thickness of the vaginal epithelium can impact sustained drug delivery. In recent years, polymers have been designed to tackle challenges mentioned above. In particular, thermosensitive hydrogels hold great promise due to their stability, biocompatibility, adhesion properties and adjustable drug release kinetics. Here, we discuss the physiological and anatomical uniqueness of the vaginal environment and how it impacts the safe and efficient vaginal delivery and also reviewed several thermosensitive hydrogels deemed suitable for vaginal drug delivery by addressing specific characteristics, which are essential to engage the vaginal environment successfully.

Uterine peristalsis and fertility: current knowledge and future perspectives: a review and meta-analysis

Although uterine contractions in the non-pregnant uterus have been studied extensively, the knowledge gained has not been used in general fertility treatment work-up. In this review paper, we provide an overview of the current knowledge on uterine peristalsis (UP), based on the available literature. This literature shows that UP influences pregnancy chances in both natural and artificial cycles. Although the physiological background of these contractions is not completely clear, we know that several factors can be of influence, like uterine pathologies and hormones. Several options to alter pregnancy outcome by interfering with uterine contractions have been studied. Our meta-analysis on therapeutic options shows positive results of progesterone at time of embryo transfer in IVF cycles or prostaglandins at time of intrauterine insemination, although the quality of evidence is low. These therapies are probably most beneficial in selected groups of patients with abnormal contraction patterns. The introduction of an objective and user-friendly UP measuring tool suitable for use in daily practice would make it possible to identify and monitor these patients. We suggest that future research should focus on the physiology of initiation of UP and on the development of an effective standard measuring tool.

In vitro bioassay investigations of the endocrine disrupting potential of steviol glycosides and their metabolite steviol, components of the natural sweetener Stevia

The food industry is moving towards the use of natural sweeteners such as those produced by Stevia rebaudiana due to the number of health and safety concerns surrounding artificial sweeteners. Despite the fact that these sweeteners are natural; they cannot be assumed safe. Steviol glycosides have a steroidal structure and therefore may have the potential to act as an endocrine disruptor in the body. Reporter gene assays (RGAs), H295R steroidogenesis assay and Ca(2+) fluorimetry based assays using human sperm cells have been used to assess the endocrine disrupting potential of two steviol glycosides: stevioside and rebaudioside A, and their metabolite steviol. A decrease in transcriptional activity of the progestagen receptor was seen following treatment with 25,000 ng/ml steviol in the presence of progesterone (157 ng/ml) resulting in a 31% decrease in progestagen response (p=<0.01). At the level of steroidogenesis, the metabolite steviol (500-25,000 ng/ml) increased progesterone production significantly by 2.3 fold when exposed to 10,000 ng/ml (p=<0.05) and 5 fold when exposed to 25,000 ng/ml (p=<0.001). Additionally, steviol was found to induce an agonistic response on CatSper, a progesterone receptor of sperm, causing a rapid influx of Ca(2+). The response was fully inhibited using a specific CatSper inhibitor. These findings highlight the potential for steviol to act as a potential endocrine disruptor.

Steroid hormones in bovine oviductal fluid during the estrous cycle

Ovarian steroid hormones are major regulators of the physiology of the oviduct and reproductive events occurring within the oviduct. To establish a whole steroid profiling of the bovine oviductal fluid (OF) during the estrous cycle, contralateral and ipsilateral (to the corpus luteum or preovulatory follicle) oviducts were classified into four stages of the estrous cycle (n = 18-27 cows per stage): postovulatory (Post-ov), mid-luteal (Mid-lut), late luteal (Late-lut), and preovulatory on the basis of the ovarian morphology and intrafollicular steroid concentrations. Steroids were extracted from pools of 150 to 200 μL OF (three to 10 cows per pool; three to four pools per "stage × side" group), purified, fractioned by high-performance liquid chromatography, and analyzed by gas chromatography coupled with tandem mass spectrometry. The concentrations of progesterone (P4) in ipsilateral OF increased from Post-ov (56.9 ± 13.4 ng/mL) to Mid-lut (120.3 ± 34.3 ng/mL), then decreased from Late-lut (76.7 ± 1.8 ng/mL) to Pre-ov (6.3 ± 1.7 ng/mL), and were four to 16 times higher than in contralateral OF. Most P4 metabolites followed similar patterns of variation. Concentrations of 17beta-estradiol (E2) were significantly higher at Pre-ov (290.5 ± 63.2 pg/mL) compared with all other stages (<118.3 pg/mL), with no difference regarding the side of ovulation. Concentrations of androstenedione displayed a pattern similar to that of E2, whereas other androgens, estrone, and corticoids did not vary between stages or sides. In conclusion, a highly concentrated and fluctuating hormonal environment was evidenced in the bovine OF. These results could be useful to improve media for IVF, embryo development, and culture of oviductal cells.

Outstanding questions concerning sperm-epithelial binding in the mammalian oviduct

Preovulatory binding of viable spermatozoa in the oviduct isthmus is widely accepted as a preliminary to fertilization, but details of physiological events associated with epithelial binding and release from binding are themselves little understood. Important questions include the potential number, distribution and stability of such sites in the caudal isthmus, whether multiple molecular forms of binding exist within a single-mated individual, and whether some sites are more favourable than others for the maintenance of preovulatory sperm viability. Also to be resolved is whether spermatozoa interact with the first available binding sites in the isthmus, whether spermatozoa from second or subsequent matings bind closer to the site of fertilization, and whether the first spermatozoa entering the oviduct are those that will be released first with impending ovulation. Ideally, future research needs to focus on a fertilizing spermatozoon monitored in vivo and not on spermatozoa destined to remain on or in the zona pellucida or in the lower reaches of the oviduct.

Steroids in the equine oviduct: synthesis, local concentrations and receptor expression

Steroids play an important role in mammalian reproduction and early pregnancy. Although systemic changes in steroid concentrations have been well documented, it is not clear how these correlate with local steroid concentrations in the genital tract. We hypothesised that, in the horse, the preimplantation embryo may be subjected to high local steroid concentrations for several days. Therefore, we measured progesterone, 17-hydroxyprogesterone, 17?-oestradiol, testosterone and 17?-testosterone concentrations in equine oviductal tissue by ultra-HPLC coupled with tandem mass spectrometry, and progesterone, 17?-oestradiol, oestrone and testosterone concentrations in oviduct fluid by radioimmunoassay, with reference to cycle stage and side of ovulation. Progesterone concentrations were high in oviductal tissue and fluid ipsilateral to the ovulation side during dioestrus, whereas other steroid hormone concentrations were not influenced by the side of ovulation. These results suggest that the high ipsilateral progesterone concentration is caused by: (1) contributions from the follicular fluid in the oviduct and diffusion of follicular fluid steroids after ovulation; (2) local transfer of steroids via blood or lymph; (3) local synthesis of progesterone in the oviduct, as evidenced by the expression of steroidogenic enzymes; and (4) a paracrine contribution from follicular cells. These data provide a basis for the study of the importance of endocrine and paracrine signalling during early embryonic development in the horse.

Influence of intracervical and intravaginal seminal plasma on the endometrium in assisted reproduction: a double-blind, placebo-controlled, randomized study

OBJECTIVE

To investigate the effect of intracervical and intravaginal application of seminal plasma on the endometrium, as assessed by endometrial/subendometrial vascularization and endometrial volume between the day of oocyte retrieval and the day of embryo transfer in an in-vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycle.

METHODS

This was a double-blind, placebo-controlled, randomized study including patients undergoing a first or second IVF/ICSI cycle. Homologous seminal plasma or placebo (sodium chloride) was injected into the cervix and posterior vaginal fornix just after follicle aspiration. Three-dimensional power Doppler examination was performed 30 min before oocyte retrieval and 30 min before embryo transfer. Main outcome measures were changes in vascularization flow index (VFI), flow index (FI) and vascularization index (VI) of the endometrium/subendometrium using VOCAL™ (Virtual Organ Computer-aided AnaLysis) and endometrial volume.

RESULTS

One hundred patients agreed to participate in the study. Twenty-three patients were excluded, mainly as a result of canceled embryo transfer. Data were analyzed from 40 patients receiving seminal plasma and 37 receiving placebo. No significant differences between the two groups were seen in VFI, FI or VI of the endometrium or subendometrium or in endometrial volume on the day of oocyte pick-up and on the day of embryo transfer.

CONCLUSION

Neither endometrial/subendometrial vascularization parameters nor endometrial volume seem to be affected by the application of seminal plasma in patients undergoing their first or second IVF/ICSI cycle.

Timing of oviductal fluid collection, steroid concentrations, and sperm preservation method affect porcine in vitro fertilization efficiency

OBJECTIVE

To determine optimal conditions for the inclusion of oviductal fluid (OF) in IVF protocols.

DESIGN

Experimental prospective study.

SETTING

Mammalian reproduction research laboratory.

ANIMAL(S)

Oviducts and ovaries from porcine females were collected at a slaughterhouse. A total of 30 oviducts and 1,285 oocytes were used. Boar-ejaculated spermatozoa were also used.

INTERVENTION(S)

In vitro-matured porcine oocytes were preincubated with OF collected from animals before or after ovulation and later fertilized in vitro. Zona pellucida digestion time in oocytes after preincubation in OF was assessed. Concentrations of E2 and P4 in OF were measured. IVF was performed, including within the culture media the E2 and P4 concentrations found in the preovulatory OF. The effect of preovulatory OF on IVF efficiency was compared between fresh and frozen-thawed spermatozoa.

MAIN OUTCOME MEASURE(S)

E2 and P4 concentrations in OF; penetration and monospermy rates; number of spermatozoa within the ooplasm and on the zona pellucida after IVF under different experimental conditions; zona pellucida resistance to protease digestion.

RESULT(S)

Preincubation of oocytes in OF collected before ovulation enhances IVF efficiency in the pig compared with OF collected after ovulation (29.58 ± 3.84 vs. 11.03 ± 2.69). When frozen-thawed spermatozoa are used for the IVF of these OF-treated oocytes, their fertilization ability increases compared with fresh semen. OF collected before and after ovulation shows significantly different concentrations of E2 (99.00 ± 8.72 vs. <10 pg/mL) and P4 (2.53 ± 0.66 vs. 12.27 ± 2.33 ng/mL), respectively. Addition of E2 and P4 at concentrations similar to those in the OF before ovulation partially simulates the effect of the fluid on IVF outcome.

CONCLUSION(S)

Preincubation of oocytes in OF collected before ovulation is a suitable protocol for increasing the efficiency of IVF with fresh semen in the pig model and could be a useful tool to increase the fertilization ability of frozen-thawed spermatozoa in other species. E2 concentrations in preovulatory OF are higher than those reported in blood serum at the same phase of the estrous cycle.

Free and sulfated steroids secretion in postpubertal boars (Sus scrofa domestica)

Sulfated steroids have been traditionally regarded as inactive metabolites. However, they may also serve as precursors for the production of active free steroids in target cells. In this study, we used the boar as a model to study the metabolism, transport, and function of steroid sulfates due to their high production in the porcine testicular–epididymal compartment, of which the role is unknown. To characterize the secretion of free and sulfated steroids, plasma samples were collected from six postpubertal boars over 6 h every 20 min from the jugular vein. Long-term secretion profiles were also established in seven boars stimulated with human chorionic gonadotropin. To directly characterize the testicular output, samples were collected from superficial testicular arterial and venous blood vessels. Testosterone, androstenedione and sulfated pregnenolone, DHEA, estrone (E1), and estradiol-17β (E2) were determined by liquid chromatography–tandem mass spectrometry. Free E1 and E2 were measured by RIA. Irrespective of a high variability between individuals, the results suggest that i) all steroids assessed are primarily produced in the testis, ii) they exhibit similar profiles pointing to a pulsatile secretion with low frequency (three to five pulses per day), and iii) after synthesis at least a major proportion is immediately released into peripheral circulation. The fact that all steroid sulfates assessed are original testicular products and their high correlations with one another suggest their role as being intermediates of testicular steroidogenesis rather than as being inactivated end products. Moreover, a substantial use of sulfated steroids in porcine testicular steroidogenesis would assign a crucial regulatory role to steroid sulfatase, which is highly expressed in Leydig cells.

Seminal plasma insemination during ovum-pickup--a method to increase pregnancy rate in IVF/ICSI procedure. A pilot randomized trial

PURPOSE

In IVF procedures, endometrial function is a limiting factor of the pregnancy rate and the aims of this study is to determine whether seminal plasma insemination at ovum pick-up in IVF has any effect on pregnancy rate.

METHODS

We designed a single center, 2 parallel groups, randomized pilot study. All couples undergoing an IVF procedure in our clinic between January 2010 and December 2011 were considered for enrollment in the study. The patients who met the inclusion criteria were randomized into two groups by simple randomization: the seminal plasma group (SP group) and the reference group (noSP group). We applied seminal plasma into the cervix and vaginal vault at the time of the OPU in the patients of the SP group. The primary outcome was the clinical pregnancy rate in the SP group compared with the noSP group and the secondary outcome measure was the implantation rate.

RESULTS

400 patients met the inclusion criteria and were randomized. 54 patients were excluded from the study mainly because they didn't undergo the embryo transfer. Finally, 164 patients were included in the SP group and 182 patients in the noSP group and analyzed. We found a statistically non-significant increase in the pregnancy rate in the SP group (55.5 % versus 44 %, p=0.09) and a statistically significant increase in the implantation rate (34.7 % versus 27.5 %, p=0.026).

CONCLUSIONS

Our results support the idea that SP insemination may have the potential to increase pregnancy rate in IVF procedures but further studies must be carried out.

Correlations between ultrasonographic characteristics of corpora lutea and systemic concentrations of progesterone during the discrete stages of corpora lutea lifespan and secretory activity in cyclic ewes

Associations between physical characteristics and functionality of corpora lutea (CL) have previously been reported in monovulatory species, albeit several studies in cattle and humans have refuted the existence of temporal relationships between CL size, echotexture and serum progesterone (P(4)) concentrations. The main objective of the present study was to examine whether or not there were correlations between ultrasonographic image attributes of CL and systemic concentrations of P(4) during the discrete stages of the luteal phase in two breeds of sheep differing in ovulation rates (non-prolific Western White Face [WWF] ewes and prolific Finn [F] sheep). Transrectal ovarian ultrasonography utilized a 7.5-MHz linear-array transducer connected to a portable scanner (Aloka SSD-500) and the images were analyzed using commercially available image analytical software (Image ProPlus(®)) validated for the present application in sheep. The correlations were assessed using the Pearson's Product Moment (PPM) analysis and also, to increase the accuracy of statistical tests, the analysis of covariance (ANCOVA), with the number of CL as a co-factor. In WWF ewes, serum concentrations of P(4) correlated significantly with the total luteal area (TLA) during the CL growth phase (days 3-6; day 0 = ovulation) and functional luteolysis (days 12-15), and with numerical pixel values (NPVs--pixel intensity) during luteolysis; the results obtained by using two different statistical methods were generally similar. In prolific F ewes, serum P(4) concentrations were directly correlated with TLA during CL growth (days 3-6; ANCOVA), functional luteolysis (days 13-14; PPM), and structural CL regression (days 11-14; PPM and ANCOVA), and with NPVs during functional luteolysis (PPM and ANCOVA). We concluded that systemic P(4) concentrations could only be accurately predicted from the changes in luteal area during CL growth and regression, and from NPVs during luteolysis, in both prolific and non-prolific ewes, but the changes in size and echotexture of the luteal glands at mid-cycle were not indicative of serum P(4) concentrations in sheep.