The presence and function of dopamine type 2 receptors in boar sperm: a possible role for dopamine in viability, capacitation, and modulation of sperm motility

An association weight matrix identified biological pathways associated with bull fertility traits in a multi-breed population

Using seven indicator traits, we investigated the genetic basis of bull fertility and predicted gene interactions from SNP associations. We used percent normal sperm as the key phenotype for the association weight matrix-partial correlation information theory (AWM-PCIT) approach. Beyond a simple list of candidate genes, AWM-PCIT predicts significant gene interactions and associations for the selected traits. These interactions formed a network of 537 genes: 38 genes were transcription cofactors, and 41 genes were transcription factors. The network displayed two distinct clusters, one with 294 genes and another with 243 genes. The network is enriched in fertility-associated pathways: steroid biosynthesis, p53 signalling, and the pentose phosphate pathway. Enrichment analysis also highlighted gene ontology terms associated with 'regulation of neurotransmitter secretion' and 'chromatin formation'. Our network recapitulates some genes previously implicated in another network built with lower-density genotypes. Sequence-level data also highlights additional candidate genes relevant to bull fertility, such as FOXO4, FOXP3, GATA1, CYP27B1, and EBP. A trio of regulatory genes-KDM5C, LRRK2, and PME-was deemed core to the network because of their overarching connections. This trio probably influences bull fertility through their interaction with genes, both known and unknown as to their role in male fertility. Future studies may target the trio and their target genes to enrich our understanding of male fertility further.

Epithelium-derived 6-nitrodopamine modulates noradrenaline-induced contractions in human seminal vesicles

AIMS

To evaluate the basal release of 6-nitrodopamine (6-ND) from human isolated seminal vesicles (HISV) and to characterize its action and origin.

MAIN METHODS

Left HISV obtained from patients undergoing prostatectomy surgery was suspended in a 3-mL organ bath containing warmed (37 °C) and gassed (95%O2:5%CO2) Krebs-Henseleit's solution (KHS) with ascorbic acid. An aliquot of 2 mL of the supernatant was used to quantify catecholamines by LC-MS/MS. For functional studies, concentration-responses curves to catecholamines were obtained, and pEC50 and Emax values were calculated. Detection of tyrosine hydroxylase and S100 protein were also carried out by both immunohistochemistry and fluorescence in-situ hybridization assays (FISH).

KEY FINDINGS

Basal release of 6-ND was higher than the other catecholamines (14.76 ± 14.54, 4.99 ± 6.92, 3.72 ± 4.35 and 5.13 ± 5.76 nM for 6-ND, noradrenaline, adrenaline, and dopamine, respectively). In contrast to the other catecholamines, the basal release of 6-ND was not affected by the sodium current (Nav) channel inhibitor tetrodotoxin (1 μM; 10.4 ± 8.9 and 10.4 ± 7.9 nM, before and after tetrodotoxin, respectively). All the catecholamines produced concentration-dependent HISV contractions (pEC50 4.1 ± 0.2, 4.9 ± 0.3, 5.0 ± 0.3, and 3.9 ± 0.8 for 6-ND, noradrenaline, adrenaline, and dopamine, respectively), but 6-ND was 10-times less potent than noradrenaline and adrenaline. However, preincubation with very low concentration of 6-ND (10-8 M, 30 min) produced significant leftward shifts of the concentration-response curves to noradrenaline. Immunohistochemical and FISH assays identified tyrosine hydroxylase in tissue epithelium of HISV strips.

SIGNIFICANCE

Epithelium-derived 6-ND is the major catecholamine released from human isolated seminal vesicles and that modulates smooth muscle contractility by potentiating noradrenaline-induced contractions.

Biogenic amines in the testis: sources, receptors and actions

Biogenic amines are signaling molecules with multiple roles in the central nervous system and in peripheral organs, including the gonads. A series of studies indicated that these molecules, their biosynthetic enzymes and their receptors are present in the testis and that they are involved in the regulation of male reproductive physiology and/or pathology. This mini-review aims to summarize the current knowledge in this field and to pinpoint existing research gaps. We suggest that the widespread clinical use of pharmacological agonists/antagonists of these signaling molecules, calls for new investigations in this area. They are necessary to evaluate the relevance of biogenic amines for human male fertility and infertility, as well as the potential value of at least one of them as an anti-aging compound in the testis.

Dopamine receptor D2 regulates genes involved in germ cell movement and sperm motility in rat testes†

The function of dopamine receptor D2 (D2R) is well associated with sperm motility; however, the physiological role of D2R present on testicular cells remains elusive. The aim of the present study is to delineate the function of testicular D2R. Serum dopamine levels were found to decrease with age, whereas testicular D2R expression increased. In rat testicular sections, D2R immunolabeling was observed in interstitial cells, spermatogonia, spermatocytes and mature elongated spermatids, whereas tyrosine hydroxylase immunolabeling was selectively detected in Leydig cells. In vitro seminiferous tubule culture following bromocriptine (D2R agonist) treatment resulted in decreased cAMP levels. Microarray identified 1077 differentially expressed genes (511 up-regulated, 566 down-regulated). The majority of differentially expressed genes were present in post-meiotic cells including early and late spermatids, and sperm. Gene ontology elucidated processes related to extra-cellular matrix to be enriched and was supported by differential expression of various collagens and laminins, thereby indicating a role of dopamine in extra-cellular matrix integrity and transport of spermatids across the seminiferous epithelium. Gene ontology and enrichment map also highlighted cell/sperm motility to be significantly enriched. Therefore, genes involved in sperm motility functions were further validated by RT-qPCR. Seven genes (Akap4, Ccnyl1, Iqcf1, Klc3, Prss55, Tbc1d21, Tl18) were significantly up-regulated, whereas four genes (Dnah1, Dnah5, Clxn, Fsip2) were significantly down-regulated by bromocriptine treatment. The bromocriptine-stimulated reduction in seminiferous tubule cyclic AMP and associated changes in spermatid gene expression suggests that dopamine regulates both spermatogenesis and spermiogenesis within the seminiferous epithelium, and spermatozoa motility following spermiation, as essential processes for fertility.

New insights into sperm physiology regulation: Enlightenment from G-protein-coupled receptors

BACKGROUND

G-protein-coupled receptors are critical in many physiological and pathological processes in various organs. Serving as the control panel for sensing extracellular stimuli, G-protein-coupled receptors recognise various ligands, including light, temperature, odours, pheromones, hormones, neurotransmitters, chemokines, etc. Most recently, G-protein-coupled receptors residing in spermatozoa have been found to be indispensable for sperm function.

OBJECTIVE

Here, we have summarised cutting-edge findings on the functional mechanisms of G-protein-coupled receptors that are known to be associated with sperm functions and the activation of their downstream effectors, providing new insights into the roles of G-protein-coupled receptors in sperm physiology.

RESULTS

Emerging studies hint that alterations in G-protein-coupled receptors could affect sperm function, implicating their role in fertility, but solid evidence needs to be continuing excavated with various means. Several members of the G-protein-coupled receptor superfamily, including olfactory receptors, opsins, orphan G-protein-coupled receptors, CXC chemokine receptor 4, CC chemokine receptor 5 and CC chemokine receptor 6 as well as their downstream effector β-arrestins, etc., were suggested to be essential for sperm motility, capacitation, thermotaxis, chemotaxis, Ca2+ influx through CatSper channel and fertilisation capacity.

CONCLUSION

The present review provides a comprehensive overview of studies describing G-protein-coupled receptors and their potential action in sperm function. We also present a critical discussion of these issues, and a possible framework for future investigations on the diverse ligands, biological functions and cell signalling of G-protein-coupled receptors in spermatozoa. Here, the G-protein-coupled receptors and their related G proteins that specifically were identified in spermatozoa were summarised, and provided references valuable for further illumination, despite the evidence that is not overwhelming in most cases.

An Exploratory Data Analysis from Ovine and Bovine RNA-Seq Identifies Pathways and Key Genes Related to Cervical Dilatation

The present study developed a review and exploration of data in public and already validated repositories. The main objective was to identify the pathways involved in ruminants' cervical dilatation, which are conserved between cattle and sheep in the follicular and luteal phases of the reproductive cycle. In cattle, 1961 genes were more differentially expressed in the follicular phase and 1560 in the luteal phase. An amount of 24 genes were considered exclusively expressed from these. A total of 18 genes were in the follicular phase and 6 genes were in the luteal phase. In sheep, 2126 genes were more differentially expressed in the follicular phase and 2469 genes were more differentially expressed in the luteal phase. Hoxb genes were identified in both species and are correlated with the PI3K/Akt pathway. PI3K/Akt was also found in both cattle and sheep, appearing prominently in the follicular and luteal phases of both species. Our analyses have pointed out that the PI3K/Akt pathway and the Hoxb genes appear in prominence in modulating mechanisms that involve estrus alterations in the cervix. PI3K/Akt appears to be an important pathway in the cervical relaxation process.

Genome-wide association study reveals candidate markers related to field fertility and semen quality traits in Holstein-Friesian bulls

In vitro assessment of bull semen quality is routinely used in bull semen processing centres in order to ensure that semen destined to be used in the field has passed minimum standards. Despite these stringent quality control checks, individual bulls that pass the quality control checks can still vary in field fertility by up to 25%. A genome-wide association study was undertaken to determine genetic markers associated with prefreeze and post-thaw bull sperm quality traits as well as field fertility. Genome-wide association analysis was performed using a single nucleotide polymorphism (SNP) regression mixed linear model in WOMBAT. Genes within a 250 Kb span of a suggestive (P ≤ 1 × 10^-5) SNP were considered as candidate genes. One SNP was associated with adjusted pregnancy rate, and 21 SNPs were associated across the seven semen quality traits (P ≤ 1 × 10^-5). Functional candidate genes include SIPA1L2 which was associated with adjusted pregnancy rate. This encodes a Rap GTPase-activating protein involved in Rap1 signalling pathway and was previously found to play a role in the process of sperm differentiation. Gene ontology (GO) analysis also identified significantly enriched biological processes involved protein tyrosine kinase activity including genes such as DYRK1A, TEC and TXK that were associated with sperm motility prior to freezing. Another candidate gene associated with post-thaw sperm motility was FHDC1 which coordinates actin filament and microtubule dynamics. The induced 11 GO terms in the ejaculates rejected after freezing trait were related to ATPase, phosphatase and hydrolase activity. These results reveal novel specific genomic regions and candidate genes associated with economically important phenotypes such as field fertility and semen quality traits.

Microbiome–Metabolome Reveals the Contribution of the Gut–Testis Axis to Sperm Motility in Sheep (Ovis aries)

A close association exists among testicular function, gut microbiota regulation, and organismal metabolism. In this study, serum and seminal plasma metabolomes, and the rumen microbiome of sheep with significant differences in sperm viability, were explored. Serum and seminal plasma metabolomes differed significantly between high-motility (HM) and low-motility (LM) groups of sheep, and 39 differential metabolites closely related to sperm motility in sheep were found in seminal plasma metabolomes, while 35 were found in serum samples. A 16S rRNA sequence analysis showed that the relative abundance of HM and LM rumen microorganisms, such as Ruminococcus and Quinella, was significantly higher in the HM group, whereas genera such as Rikenellaceae_RC9_gut_group and Lactobacillus were enriched in the mid-LM group. Serum hormone assays revealed that serum follicle-stimulating hormone (FSH) and MT levels were significantly lower in the LM group than in the HM group, whereas serum glucocorticoid (GC) levels were higher in the LM group than in the HM group, and they all affected sperm motility in sheep. Ruminococcus and other rumen microorganisms were positively correlated with sperm motility, whereas Lactobacillus was negatively correlated with FSH and GCs levels. Our findings suggest that rumen microbial activity can influence the host metabolism and hormone levels associated with fertility in sheep.

High concentration of dopamine treatment may induce acceleration of human sperm motility

Purpose

In humans, catecholamines (including dopamine) have been identified in semen and fallopian tubes, while dopamine D2 receptors (D2DR) are found in the sperm midpiece region. How dopamine dose affects human sperm function and whether dopamine treatment is useful in assisted reproductive technology is unclear.

Methods

Sperm samples were obtained from patients with normal semen parameters undergoing fertility treatment. We investigated the effects of dopamine treatment on tyrosine phosphorylation and sperm motility. Sperm motility was analyzed using the computer-assisted sperm analysis (CASA) system.

Results

This study revealed that various dopamine concentrations (0.1-100 μM) did not increase sperm tyrosine phosphorylation. Progressive motility increased substantially when treated with high concentrations of dopamine (10 and 100 μM) and was blocked by raclopride (a D2DR antagonist). After 24-h sperm culture, the addition of 10 μM dopamine significantly increased curvilinear velocity and amplitude of lateral head displacement, which are indicators of hyperactivation.

Conclusion

Dopamine did not affect tyrosine phosphorylation, but increased sperm motility. High concentrations of dopamine were more effective to accelerate sperm motility in cases where sperm motile capacity was low.

Methylmercury exposure-induced reproductive effects are mediated by dopamine in Caenorhabditis elegans

Methylmercury (MeHg) is a neurotoxicant that exists in the natural environment, which level can be greatly increased because of human activity. MeHg exposures have the risk of being detrimental to the development of the nervous system. Studies on MeHg toxicity have largely focused on the mechanisms of its neurotoxicity following developmental exposures. Additionally, reproductive toxicity of developmental MeHg exposures has been noted in rodent models. The model organism Caenorhabditis elegans (C. elegans) is a self-fertilizing animal which has a short lifespan around 20 days. Most C. elegans are hermaphrodites that can generate both sperm and oocytes. To investigate the effects of developmental MeHg exposures on the reproduction in C. elegans, larvae stage 1 worms were exposed to MeHg (0, 0.01 or 0.05 μM) for 24 h. The laid eggs and oocytes were compared during each day at adult stages for 6 days. We showed that MeHg exposure significantly induced an increased number of eggs in day 1 adults without an effect on the timing of egg laying or the total number of eggs or oocytes over the 6-day period. The expression of dat-1 and cat-2 and dopamine levels were increased in worms exposed to MeHg. Supplementation with 100 μM dopamine recapitulated the effect of MeHg on the number of eggs present in day 1 adults. Furthermore, the effect of MeHg on the number of eggs was abrogated in the cat-2 mutant worms CB1112. The number of oocytes in the 6-day adult stages was decreased by MeHg in the dat-1 mutant RM2702. MeHg exposures did not change the mating rate or the number of offspring from mating. Combined, these novel findings show that developmental exposure to low levels of MeHg has limited effects on the reproduction in C. elegans. Furthermore, our data support a modulatory role of dopamine in MeHg-induced effects on reproduction in this model system.

Metabolomics of Human Semen: A Review of Different Analytical Methods to Unravel Biomarkers for Male Fertility Disorders

Background: Human life without sperm is not possible. Therefore, it is alarming that the fertilizing ability of human spermatozoa is continuously decreasing. The reasons for that are widely unknown, but there is hope that metabolomics-based investigations may be able to contribute to overcoming this problem. This review summarizes the attempts made so far. Methods: We will discuss liquid chromatography–mass spectrometry (LC-MS), gas chromatography (GC), infrared (IR) and Raman as well as nuclear magnetic resonance (NMR) spectroscopy. Almost all available studies apply one of these methods. Results: Depending on the methodology used, different compounds can be detected, which is (in combination with sophisticated methods of bioinformatics) helpful to estimate the state of the sperm. Often, but not in all cases, there is a correlation with clinical parameters such as the sperm mobility. Conclusions: LC-MS detects the highest number of metabolites and can be considered as the method of choice. Unfortunately, the reproducibility of some studies is poor, and, thus, further improvements of the study designs are needed to overcome this problem. Additionally, a stronger focus on the biochemical consequences of the altered metabolite concentrations is also required.

Influence of Prolactin Secretion Changes on Sperm Head Size and Freezability in Ibex and Mouflon

Aim: This work examined the influence of induced changes in prolactin (PRL) secretion on sperm cryoresistance of ibex and the mouflon. Materials and Methods: PRL secretion was modified in a first experiment by the use of bromocriptine (BCR, dopamine agonist) during the non-breeding season, and in a second experiment by the use of sulpiride (SLP, dopamine D₂-receptor antagonist) during the rutting season. Slow and ultra-rapid freezing protocols were used to cryopreserve sperm samples. Results: BCR decreased blood plasma PRL concentrations, whereas SLP increased them. Cryoresistance ratios (CRs) for curvilinear velocity (VCL), straight-line velocity (VSL), and average path velocity (VAP) in BCR-treated mouflons were lower than in controls using slow-freezing (p < 0.05), while CRs of motility and morphologically normal sperm of BCR-treated mouflons were greater than controls with ultra-rapid freezing (p < 0.05). BCR increased the head sperm dimensions in ibexes (p < 0.001); conversely, BCR decreased the head dimensions in mouflons (p < 0.001). CR-motility, CR-amplitude of lateral head displacement (ALH), CR-viability, and CR-acrosome integrity in SLP-treated mouflons were lower than in controls with slow-freezing (p < 0.01); CR-viability and CR-acrosome were lower than controls with ultra-rapid freezing (p < 0.05). In ibexes, CR-ALH was lower for SLP-treated (p < 0.05). SLP treatment increased head dimensions in ibexes (p < 0.001) but did not affect the sperm head of mouflons. Conclusion: Our findings show that high levels of blood plasma PRL negatively affect the cryoresistance of ibex and mouflon sperm.

Exogenous gamma-aminobutyric acid addition enhances porcine sperm acrosome reaction

The widely used porcine artificial insemination procedure involves the use of liquid‐stored semen because it is difficult to control the quality of frozen–thawed porcine sperm. Therefore, there is a high demand for porcine semen. The control and enhancement of sperm function are required for the efficient reproduction of pigs. We previously reported that gamma‐aminobutyric acid (GABA) enhanced sperm capacitation and acrosome reaction in mice. In this study, we demonstrated the presence of GABA_A receptors in porcine sperm acrosome. Furthermore, we investigated the GABA effects on porcine sperm function. We did not detect any marked effect of GABA on sperm motility and tyrosine phosphorylation of sperm proteins. However, GABA promoted acrosome reaction, which was suppressed by a selective GABA_A receptor antagonist. GABA binds to GABA_A receptors, resulting in chloride ion influx. We found that treatment with 1 μM GABA increased the intracellular concentration of chloride ion in the sperm. In addition, the GABA concentration effective in the acrosome reaction was correlated with the porcine sperm concentration. These results indicate that GABA and its receptors can act as modulators of acrosome reaction. This study is the first to report the effects of GABA on porcine sperm function.

Progesterone, Myo-Inositol, Dopamine and Prolactin Present in Follicular Fluid Have Differential Effects on Sperm Motility Subpopulations

Considering the challenges surrounding causative factors in male infertility, rather than relying on standard semen analysis, the assessment of sperm subpopulations and functional characteristics essential for fertilization is paramount. Furthermore, the diagnostic value of sperm interactions with biological components in the female reproductive tract may improve our understanding of subfertility and provide applications in assisted reproductive techniques. We investigated the response of two sperm motility subpopulations (mimicking the functionality of potentially fertile and sub-fertile semen samples) to biological substances present in the female reproductive tract. Donor semen was separated via double density gradient centrifugation, isolated into high (HM) and low motile (LM) sperm subpopulations and incubated in human tubal fluid (HTF), capacitating HTF, HD-C medium, progesterone, myo-inositol, dopamine and prolactin. Treated subpopulations were evaluated for vitality, motility percentages and kinematic parameters, hyperactivation, positive reactive oxygen species (ROS), intact mitochondrial membrane potential (MMP) and acrosome reaction (AR). While all media had a significantly positive effect on the LM subpopulation, dopamine appeared to significantly improve both subpopulations' functional characteristics. HD-C, progesterone and myo-inositol resulted in increased motility, kinematic and hyperactivation parameters, whereas prolactin and myo-inositol improved the LM subpopulations' MMP intactness and reduced ROS. Furthermore, progesterone, myo-inositol and dopamine improved the HM subpopulations' motility parameters and AR. Our results suggest that treatment of sub-fertile semen samples with biological substances present in follicular fluid might assist the development of new strategies for IVF treatment.

Semen Quality and Freezability Analyses in the Ejaculates of Two Poitou Donkeys in the Southern Hemisphere

The Baudet du Poitou is a vanishing donkey breed recognized for engendering robust working mules. In Chile, only two pure breed Poitou males exist, which belong to the Chilean army and are used for mule production. We performed an extensive sperm and seminal analysis of these two jackasses aged 3 and 6 years and investigated the use of a simple hypometabolic extender for sperm cryopreservation. Computer-assisted sperm analysis showed high motility, velocity, and linearity in sperm movement. The seminal plasma analysis revealed that sodium and chloride were the main electrolytes, and globulins were the main metabolites. Active and variable enzymatic activity was observed. New information is reported about gamma-glutamyltransferase, aspartate aminotransferase, zinc, and magnesium concentrations in seminal plasma of Poitou donkeys. Ejaculates among jackasses showed some variability due to individual variability and different stages in sexual maturation according to age. The freezability index analysis based in viability, total motility and progressive motility with Botucrio extender (57.1 ± 11.0%; 56.6 ± 20.0%; and 22.6 ± 10.3%, respectively) were significantly higher (p < 0.05, p < 0.0001, and p < 0.0001, respectively) than with HM-0 extender (42,6 ± 11.4%; 14.9 ± 5.1%; and 1.0 ± 2.5%, respectively). We report new information on Poitou donkey semen and cryopreservation in the Southern Hemisphere that could be useful in donkey breeding and conservation programs to develop strategies that improve the effectiveness of population management of this breed.

Prepubertal arsenic exposure alters phosphoproteins profile, quality, and fertility of epididymal spermatozoa in sexually mature rats

Arsenic intoxication affects male reproductive parameters of prepubertal rats. Besides, morphological and functional alterations in their testis and epididymis may remain after withdrawal of arsenic insult, causing potential impairment in male fertility during adulthood. In this study, we aimed at analyzing the effect of prepubertal arsenic exposure on the fecundity of epididymal sperm from sexually mature Wistar rats, assessing fertility indexes, sperm parameters, and sperm phosphoproteins content. Male pups on postnatal day (PND) 21 received filtered water (controls, n = 10) and 10 mg L^-1 arsenite (n = 10) daily for 30 days. From PND52 to PND81, rats from both groups received filtered water. During this period, the males mated with non-exposed females between PND72 and PND75. Our results showed that sexually mature rats presented low sperm production, epididymal sperm count, motility, and quality after prepubertal arsenic exposure. These findings possibly contributed to the low fertility potential and high preimplantation loss. Epididymal sperm proteome detected 268 proteins, which 170 were found in animals from both control and arsenic groups, 27 proteins were detected only in control animals and 71 proteins only in arsenic-exposed rats. In these animals, SPATA 18 and other five proteins were upregulated, whereas keratin type II cytoskeletal 1 was downregulated (q < 0.1). The results of KEGG pathway analysis demonstrated an enrichment of pathways related to dopaminergic response, adrenergic signaling, protein degradation, and oocyte meiosis in arsenic-exposed animals. Moreover, 26 proteins were identified by phosphoproteomic with different phosphorylation pattern in animals from both groups, but SPATA18 was phosphorylated only in arsenic-exposed animals. We concluded that prepubertal exposure to arsenic is deleterious to sperm quality and male fertility, altering the sperm phosphoproteins profile.

Effects of quetiapine administration on sperm quality and testicular histology

Quetiapine is one of the most commonly prescribed antipsychotics to treat schizophrenia in adults, in particular. In this study, quetiapine's effects were assessed on healthy sperm production in rats at repeated-pharmacological doses. Additionally, the effects of quetiapine on oxidative status and hormonal balance were also evaluated in rats. Quetiapine was administered to rats orally at 10, 20, and 40 mg/kg body weight doses for 28 days. At the end of this period, body and organ weights were measured, sperm concentration, motility, and morphology were determined, sperm damage was assessed, and histopathological analysis of testicular tissue was performed. Additionally, serum FSH, LH, and testosterone levels as male reproductive hormones were measured. Catalase, superoxide dismutase, glutathione, and malondialdehyde levels were determined for evaluating the oxidative status of testicular tissue. The findings obtained in this study showed that relative epididymis weights and sperm concentration decreased and abnormal sperm morphology increased in quetiapine-administered rats. Irregularity of typical architecture of the seminiferous tubules and germinal cell disorganization was observed in testicular sections of 20 and 40 mg/kg quetiapine-administered rats. Further, serum LH and testosterone levels decreased in 20 and 40 mg/kg quetiapine-administered rats. Additionally, decreased catalase and superoxide dismutase activities in testicular tissue of quetiapine-administered rats and increased malondialdehyde levels in testicular tissue of 40 mg/kg quetiapine-administered rats were measured. In conclusion, quetiapine treatment decreased sperm quality, altered hormone levels, and induced oxidative stress may be considered potential contributors to this adverse effect.

Does methylphenidate use affect sperm parameters in patients undergoing infertility investigation? A retrospective analysis of 9769 semen samples

OBJECTIVES

Methylphenidate (MPH) is the most widely prescribed therapy for attention deficit hyperactivity disorder. Animal studies have shown a potential adverse effect of MPH exposure on male fertility. We examined the impact of MPH on human male sperm parameters.

DESIGN

Sperm parameters of 9769 samples from patients 18 years of age or older, collected as part of the basic evaluation of couples referred to the Infertility Clinic were analyzed retrospectively. We divided the study population into three groups according to MPH purchasing information: MPH purchased ≤ 90 days prior to sperm analysis-current users (n = 83), MPH purchased > 90 days prior to sperm analysis-past users (n = 293), and MPH-naïve patients (n = 9393).

METHODS

All sperm samples were analyzed by the same laboratory technician team for the following routine parameters: semen volume, sperm concentration, percentage of motile sperm, and percentage of normal morphology according to World Health Organization. The analysis of the samples was completed by evaluation of total sperm count, total sperm motility, and percentage of fast and slow motile cells. Sperm morphology was evaluated by a laboratory technician using methodological examination according to the strict Kruger-Tygerberg criteria.

RESULTS

Methylphenidate exposure did not affect sperm morphology but was associated with increased sperm concentration as well as increased total sperm count and total sperm motility among current and past users compared with MPH-naïve patients. In particular, progressive motility and total motile sperm count were significantly increased following MPH use. A multivariate analysis adjusting for age and current smoking was conducted, further supporting a positive correlation between current MPH use and increased values of total sperm count and total sperm motility.

LIMITATIONS

Our study has several inherent weaknesses, foremost of which is its retrospective nature. Another notable weakness is that medication purchasing data may not accurately reflect MPH exposure in the study population. Patients may be purchasing MPH and not taking it as prescribed.

CONCLUSIONS

In the present study, we could not demonstrate a negative impact of methylphenidate treatment on sperm parameters in adults with ADHD. Hence, we may assume that methylphenidate does not negatively affect male fertility.

Expression and Possible Role of Nicotinic Acetylcholine Receptor ε Subunit (AChRe) in Mouse Sperm

The nicotinic acetylcholine receptor (nAChR) is one of the receptors of acetylcholine (ACh), and nicotine (NIC) acts as an agonist of this receptor. Among the nAChR subunits, we found that the ε subunit (AChRe) had approximately 10 to 1000 times higher level of mRNA expression in mouse testes than the other subunits. In this study, we aimed to elucidate the expression and localization of AChRe in the testes and spermatozoa of mice and clarify the effect of AChRe on sperm function. Immunocytochemistry showed that AChRe was expressed in the murine testes and spermatozoa. We found that AChRe was localized only in elongated spermatids from step 12 onwards in the testes. In spermatozoa, AChRe was localized in the head, especially in the anterior region of the acrosome, but only approximately 50% of spermatozoa showed this immunoreactivity. Additionally, we analyzed the effects of ACh and NIC on sperm acrosome reaction (AR) and found that both ACh and NIC suppressed the AR rate, which was restored by an AChRe-specific antagonist. These results suggest that AChRe may be a regulator of mammalian sperm AR.

Semen quality and freezability analysis during breeding and non-breeding seasons in heavy draft stallions in southern Chile

The aim of this study was to evaluate seasonal changes in basic parameters of sperm quality and freezability behaviour of ejaculates from 10 fertile heavy draft stallions. A total of 140 ejaculates were collected, processed and evaluated during both the breeding (September-November) and non-breeding seasons (April-June). Fresh semen was evaluated for volume, concentration, total spermatozoa per ejaculate, plasma membrane integrity and total sperm motility. Cryopreserved samples were evaluated for plasma membrane integrity and sperm motility by the CASA system, and for the freezability index (FI), which was defined as the decreased ratio of viability after freezing-thawing. In fresh ejaculates, only viability showed significantly higher values in the breeding than in the non-breeding season (64.0% ± 15.0% vs. 58.6% ± 12.0%, respectively; p < .05). The sperm post-thawing analysis of viability and total motility parameters showed no significant changes linked to the season. However, the FI analysis showed that the ejaculates collected in the non-breeding season had higher cryoresistance characteristics than those collected in the breeding season. Results suggest that the presence of some cryoprotective factor/s in heavy draft horse ejaculates could be modulated by seasonality, with higher protective effects in the non-breeding season.

Effect of Venlafaxine, Pramipexole, and Valsartan on Spermatogenesis in Male Rats

The study's aim was to explore the effect of venlafaxine, valsartan, and pramipexole on spermatogenesis. It was hypothesized that these drugs may affect the male fertility because of their long-term use in treatment of depression, hypertension, and Parkinson's diseases. Male rats were given venlafaxine, valsartan, and pramipexole at low- and high-dose levels orally once daily for 10 weeks. Testosterone (25 mg/kg) was given as a standard via an intramuscular route once weekly. Rats were sacrificed after blood collection by cardiac puncture, and testes were removed. Sperm parameters were examined from spermatozoa of the cauda epididymis, and testes were treated for histopathological analysis. Results showed nonsignificant effect of venlafaxine on the sperm count, whereas a decreased sperm count was noted in all the treatment groups as compared to that of the control except valsartan at a low dose, which significantly (p < 0.001) raised the sperm count (96.26 ± 2.4) in reference with the control value (49.13 ± 2.3). Treatments had variable effects on total sperm motility and morphological parameters, but valsartan at a low dose showed maximum sperm motility (71.55 ± 0.7) among all. DNA integrity of spermatozoa remained intact in all groups. Luteinizing hormone and follicle-stimulating hormone levels decreased, and testosterone levels increased in all treatment groups as compared to control values, which indicate fertility. Histopathology revealed normal texture of testes with venlafaxine and valsartan, but testicular damage occurred with high-dose pramipexole. It is concluded that the use of venlafaxine, valsartan, and pramipexole at a low dose is devoid of any harmful effect on spermatogenesis, whereas pramipexole at a high dose adversely affect it.

Exploring the Stress Impact in the Paternal Germ Cells Epigenome: Can Catecholamines Induce Epigenetic Reprogramming?

Spermatogenesis is characterized by unique epigenetic programs that enable chromatin remodeling and transcriptional regulation for proper meiotic divisions and germ cells maturation. Paternal lifestyle stressors such as diet, drug abuse, or psychological trauma can directly impact the germ cell epigenome and transmit phenotypes to the next generation, pointing to the importance of epigenetic regulation during spermatogenesis. It is established that environmental perturbations can affect the development and behavior of the offspring through epigenetic inheritance, including changes in small non-coding RNAs, DNA methylation, and histones post-translational modifications. But how male germ cells react to lifestyle stressors and encode them in the paternal epigenome is still a research gap. Most lifestyle stressors activate catecholamine circuits leading to both acute and long-term changes in neural functions, and epigenetic mechanisms show strong links to both long-term and rapid, dynamic gene expression regulation during stress. Importantly, the testis shares a molecular and transcriptional signature with the brain tissue, including a rich expression of catecholaminergic elements in germ cells that seem to respond to stressors with similar epigenetic and transcriptional profiles. In this minireview, we put on stage the action of catecholamines as possible mediators between paternal stress responses and epigenetic marks alterations during spermatogenesis. Understanding the epigenetic regulation in spermatogenesis will contribute to unravel the coding mechanisms in the transmission of the biological impacts of stress between generations.

"In vitro" capacitation and further progesterone-induced acrosome exocytosis are linked to specific changes in the expression and location of threonine phosphorylation of boar spermatozoa

The aim of this study was to determine if the achievement of the "in vitro" capacitation (IVC) status and subsequent progesterone-induced "in vitro" acrosome exocytosis (IVAE) was accompanied with overall changes in threonine phosphorylation (pThre) of boar spermatozoa. For this purpose, mono- and bi-dimensional Western blot analyses as well as immunocytochemistry studies against pThre were performed in boar sperm subjected to IVC and subsequent IVAE. Mono-dimensional Western blot in non-capacitated samples showed that launching of IVC did induce an overall increase in signal intensity in all observed bands that was followed by a subsequent decrease afterwards. Bi-dimensional Western blot analysis showed the presence of four main signal protein clusters. The attainment of IVC induced an overall decrease in the number and intensity of spots of Clusters A, B and C and a concomitant increase in the intensity of spots of Cluster D. The IVAE launching caused a rapid increase in the intensity of spots of Clusters B, C and D, which was followed by a subsequent decrease of the intensity together with a concomitant pI displacement of Cluster C. Finally, immunocytochemistry showed that the pThre signal of non-capacitated cells was located at the whole sperm. The IVC did not induce prominent changes in this location. In contrast, the induction of IVAE caused the appearance of an additional an intense acrosome and tail pThre signal that subsequently decreased. In conclusion, our results indicate that IVC and further IVAE induced specific changes in the intensity and appearance of pThre protein phosphorylation which were linked to changes of specific protein characteristics as pI. These results support, thus, the existence of a specific role of pThre in IVC/IVAE of boar sperm.

Capacitation of mouse sperm is modulated by gamma-aminobutyric acid (GABA) concentration

In mammals, ejaculated sperm acquire their fertilizing ability during migration through the female reproductive tract, which secretes several factors that contribute to sperm capacitation. Gamma-aminobutyric acid (GABA) is a well-known neurotransmitter in the central nervous system, but additionally enhances the sperm acrosome reaction in the rat and cow. However, the detailed effects of GABA concentration on sperm function remain unclear. In this study, we detected the presence of the GABA type A receptor (GABA A) in mouse epididymal sperm by western blot analysis and in the sperm acrosome by immunocytochemistry. We also investigated the effects of GABA on sperm fertilizing ability. We found that GABA facilitated the tyrosine phosphorylation of sperm proteins, which is an index of sperm capacitation. GABA also promoted the acrosome reaction, which was suppressed by a selective GABA A receptor antagonist. We then found that the effective GABA concentration for the acrosome reaction corresponds to sperm concentration, but we did not detect any marked effect of GABA on sperm motility using a computer-assisted sperm analysis system. Using immunohistochemistry, we also detected GABA expression in the epithelia of the mouse uterus and oviduct. Furthermore, we found that the mRNA levels of glutamate decarboxylase (Gad), which generates GABA from L-glutamate, were higher in the oviduct than in the uterus, and that Gad mRNA levels were higher at estrus than at the diestrus stage. These results indicate that the GABA concentration can act as a modulator of the acrosome reaction and sperm capacitation in the female reproductive tract.

Bovine dopamine type-2 receptor SNP has no effect on growth, semen characteristics and prolactin concentrations in beef bulls treated with a dopamine agonist

A dopamine type-2 receptor (DRD2) SNP, previously found to be correlated with serum prolactin (PRL) concentrations in cattle, was evaluated for impact on growth traits, serum prolactin concentration, and semen quality. Over a four-year period, yearling beef bulls were allowed diets containing or lacking ergot alkaloids (EA). Every 21 or 28 d semen was collected for semen motility and morphology assessment and blood samples were collected to measure serum PRL concentrations. In addition, body condition score and scrotal circumference were evaluated. Serum PRL concentrations were assessed using a radioimmunoassay. In the first year, all bulls were sacrificed at the end of a 126-day study. Testicles and epididymis were collected at the end of the study or 60 days after removal from treatment. Immunohistochemistry was performed on testis, epididymis, and sperm cells, incubated with or without a primary antibody for DRD2 and counterstained with DAPI. Isolation of DNA was performed on sperm pellets using DNAzol (Thermo Fisher Scientific, Waltham, MA, USA) methods. Polymerase chain reaction was performed to amplify the region of the DRD2 gene containing the SNP of interest. The products were subjected to restriction fragment length polymorphism analysis. Further, all samples were subjected to genotyping using a custom Taqman genotyping assay (Applied Biosystems, Foster city, CA, USA). The presence of DRD2 was detected in the testis, epididymis, and sperm cells. The DRD2 genotype was not associated with semen quality, serum PRL, or growth traits. Consumption of EA resulted in lesser PRL serum concentrations but had no effect on values for other variable examined.

Photostimulation and thermotaxis of sperm: Overview and practical implications in porcine reproduction

The journey of mammalian sperm through the female genital tract requires the existence of a myriad of mechanisms that allow cells to reach the oviduct in a timely manner from the place of semen deposition. Several biochemical mechanisms such as signaling through molecules like bicarbonate, neurotransmitters or even glycosaminoglycanes are known and have been studied by several relevant groups worldwide. However, biophysical mechanisms for sperm transport are much less studied and understood. Thermotaxis, for example, is a powerful, physical signaling system that is known to direct sperm inside the female genital tract, although the intimate mechanisms by which this effect is launched are yet to be elucidated. This review is focuses on the analysis of thermotaxis and its possible relationship with another phenomenon that has been observed in sperm from a variety of species, namely photostimulation. An overall review on sperm thermotaxis and putative mechanism/s that can be involved in this phenomenon is developed, followed by a description of the most recent findings on the mechanisms underlying sperm photostimulation, highlighting its possible relationship with thermotactic mechanisms. Finally, an overview regarding some practical implications of the phototactic/thermotactic phenomenon has been included in order to evaluate the possible use of techniques based on these phenomena as tools for improving pig reproduction.

Ritalinic Acid Stimulates Human Sperm Motility and Maintains Vitality In Vitro

Purpose

To evaluate the in vitro impact of ritalinic acid (RA), a major metabolite of methylphenidate (drug to treat attention-deficit hyperactivity disorder), on sperm motility, vitality and oxidative stress.

Materials and Methods

Semen samples (n=13) were collected from healthy donors and a semen analysis was performed according to World Health Organization. Density gradient centrifugation was performed to isolate motile sperm. Samples were incubated with different concentrations (0, 1, 10, 100, and 1,000 ng/mL) of RA. The non-exposed group (0 ng/mL) was defined as the control group. Samples were analyzed for motility at different time points (0, 60, 150, 240, and 300 minutes) and for vitality and oxidation reduction potential (ORP) (at 0, 240, and 300 minutes). Sperm motility was assessed manually and motion kinetic parameters were recorded by computer aided semen analysis.

Results

RA at any tested concentration significantly increased sperm motility compared to the control in a time-dependent manner with a maximum increase after 240 minutes. Motion kinetic parameters were not comparable. For sperm vitality, supplementation with RA significantly maintained survival at higher levels, while non-treated sperm gradually died. These higher levels of vitality were maintained with rising RA concentrations of up to 1,000 ng/mL. A non-significant trend of increased ORP was observed in all study groups.

Conclusions

RA increases sperm motility and maintains vitality at any concentration tested. Therefore, RA might be utilized to improve sperm quality in asthenozoospermic specimens. However, further investigation is ongoing to evaluate the effect of RA on other sperm parameters.

Improvement in blastocyst quality by neurotensin signaling via its receptors in bovine spermatozoa during in vitro fertilization

Previously, we reported that neurotensin (NT), which is expressed in the uterus and oviduct, enhanced bovine sperm capacitation and acrosome reactions. As NT mRNA expression in bovine oviducts increases dramatically in the follicular phase, we hypothesized that NT modulates fertilization and subsequent conception in cattle. The objective of this study was to evaluate the effect of NT on embryo development and blastocyst quality. The rate of embryo cleavage was significantly increased by the addition of NT to the fertilization medium. Furthermore, the total number of cells and numbers of cells in the inner cell mass of blastocysts were significantly increased by NT during in vitro fertilization (IVF). These results suggested that NT enhanced the efficiency of early bovine embryo development and blastocyst quality. The expression of NT receptors (NTRs) in sperm, testes, oocytes, and cumulus cells was evaluated to determine whether NT acted via NTRs in sperm alone or in both male and female reproductive cells during IVF. Immunocytochemistry and reverse transcription polymerase chain reaction revealed that NTR1 and NTR2 were expressed in sperm and testes, but not in oocytes and cumulus cells. We propose that NT selectively acts upon sperm via NTR1 and NTR2 during IVF to improve the cleavage rate and quality of blastocysts, which are important determinants of sperm quality for successful conception. This research supports our hypothesis that NT acts as a key modulator of fertilization and conception in cattle. Further studies are necessary to apply our findings to the industrial framework of bovine reproduction.

Repeated Clozapine Increases the Level of Serotonin 5-HT1AR Heterodimerization with 5-HT2A or Dopamine D2 Receptors in the Mouse Cortex

G-protein–coupled receptor (GPCR) heterodimers are new targets for the treatment of schizophrenia. Dopamine D₂ receptors and serotonin 5-HT_1A and 5-HT_2A receptors play an important role in neurotransmission and have been implicated in many human psychiatric disorders, including schizophrenia. Therefore, in this study, we investigated whether antipsychotic drugs (clozapine (CLZ) and haloperidol (HAL)) affected the formation of heterodimers of D₂–5-HT_1A receptors as well as 5-HT_1A–5-HT_2A receptors. Proximity ligation assay (PLA) was used to accurately visualize, for the first time, GPCR heterodimers both at in vitro and ex vivo levels. In line with our previous behavioral studies, we used ketamine to induce cognitive deficits in mice. Our study confirmed the co-localization of D₂/5-HT_1A and 5-HT_1A/5-HT_2A receptors in the mouse cortex. Low-dose CLZ (0.3 mg/kg) administered repeatedly, but not CLZ at 1 mg/kg, increased the level of D₂–5-HT_1A and 5-HT_1A–5-HT_2A heterodimers in the mouse prefrontal and frontal cortex. On the other hand, HAL decreased the level of GPCR heterodimers. Ketamine affected the formation of 5-HT_1A–5-HT_2A, but not D₂–5-HT_1A, heterodimers.

Sperm count and motility are quantitatively affected by functional polymorphisms of HTR2A, MAOA and SLC18A

Spermatozoa and neurones share similar membrane characteristics and features. Associations of multiple polymorphisms traditionally related to neurotransmission were investigated. Infertile men were grouped into controls with normospermia (n = 182) and idiopathic infertile men with asthenozoospermia (n = 103), and analysed as a case-control study and as a quantitative association of each genotype. Ten neurotransmission-associated genetic variants were mapped by SNP analysis using quantitative polymerase chain reaction with TaqMan probes. Men with HTR2A rs6313 had a higher risk of asthenozoospermia (OR = 2.14; P = 0.04). MAOA rs3788862 G carriers displayed an increased risk of asthenozoospermia (OR = 2.29; P = 0.02). The SLC18A1 rs1390938 G allele was more frequent among such cases (0.75 versus 0.87; P < 0.01 and P < 0.01 for Armitage trend test); for SLC18A1 rs2270641 P = 0.02 (case-control frequency) and P = 0.01 (Armitage trend test). MAOA rs3788862 was correlated with sperm motility (Spearman ρ = 0.14; P = 0.02); SLC18A1 rs1390938 was correlated with sperm count and motility (Spearman ρ = 0.20; P < 0.01). Gene polymorphisms of HTR2A, MAOA and SLC18A1, related to neurotransmission, are individually associated with asthenozoospermia through variation in sperm count and motility, without detectable allelic or genotype interaction.

Effects on Sperms' Quality of Selegiline in Aged Rats

Background

Selegiline is used to treat Parkinsonian patients. Other indications of its use have recently been discovered.

Objective

Scouting special and beneficial side effects of selegiline treatment.

Method

Two-year old male Wistar rats were daily treated with 0.25 mg/kg of selegiline s.c. (subcutaneous injection). The rats were sacrificed following a four-weeks' treatment.

Results

Mass of testes, number of sperms, progressive motility of sperms, and their viability definitely increased.

Conclusion

Selegiline can successfully be used to stop/counterbalance certain symptoms of aging.

Neuronal signaling repertoire in the mammalian sperm functionality

The common embryonic origin has been a recurrent explanation to understand the presence of "neural receptors" in sperm. However, this designation has conditioned a bias marked by the classical neurotransmission model, dismissing the possibility that neurotransmitters can play specific roles in the sperm function by themselves. For instance, the launching of acrosome reaction, a fundamental sperm function, includes several steps that recall the process of presynaptic secretion. Unlike of postsynaptic neuron, whose activation is mediated by molecular interaction between neurotransmitter and postsynaptic receptors, the oocyte activation is not mediated by receptors, but by cytosolic translocation of sperm phospholipase (PLCζ). Thus, the sperm has a cellular design to access and activate the oocyte and restore the ploidy of the species by an "allogenic pronuclear fusion." At subcellular level, the events controlling sperm function, particularly the capacitation process, are activated by chemical signals that trigger ion fluxes, sterol oxidation, synthesis of cyclic adenosine monophosphate, protein kinase A activation, tyrosine phosphorylations and calcium signaling, which correspond to second messengers similar to those associated with exocytosis and growth cone guidance in neurons. Classically, the sperm function associated with neural signals has been analyzed as a unidimensional approach (single ligand-receptor effect). However, the in vivo sperm are exposed to multidimensional signaling context, for example, the GABAergic, monoaminergic, purinergic, cholinergic, and melatoninergic, to name a few. The aim of this review is to present an overview of sperm functionality associated with "neuronal signaling" and possible cellular and molecular mechanisms involved in their regulation.

Histological and transcriptomic effects of 17α-methyltestosterone on zebrafish gonad development

BACKGROUND

Sex hormones play important roles in teleost ovarian and testicular development. In zebrafish, ovarian differentiation appears to be dictated by an oocyte-derived signal via Cyp19a1a aromatase-mediated estrogen production. Androgens and aromatase inhibitors can induce female-to-male sex reversal, however, the mechanisms underlying gonadal masculinisation are poorly understood. We used histological analyses together with RNA sequencing to characterise zebrafish gonadal transcriptomes and investigate the effects of 17α-methyltestosterone on gonadal differentiation.

RESULTS

At a morphological level, 17α-methyltestosterone (MT) masculinised gonads and accelerated spermatogenesis, and these changes were paralleled in masculinisation and de-feminisation of gonadal transcriptomes. MT treatment upregulated expression of genes involved in male sex determination and differentiation (amh, dmrt1, gsdf and wt1a) and those involved in 11-oxygenated androgen production (cyp11c1 and hsd11b2). It also repressed expression of ovarian development and folliculogenesis genes (bmp15, gdf9, figla, zp2.1 and zp3b). Furthermore, MT treatment altered epigenetic modification of histones in zebrafish gonads. Contrary to expectations, higher levels of cyp19a1a or foxl2 expression in control ovaries compared to MT-treated testes and control testes were not statistically significant during early gonad development (40 dpf).

CONCLUSION

Our study suggests that both androgen production and aromatase inhibition are important for androgen-induced gonadal masculinisation and natural testicular differentiation in zebrafish.

Characterization of non-olfactory GPCRs in human sperm with a focus on GPR18

G protein-coupled receptors (GPCRs) transduce external chemical cues into intracellular signals and are involved in a plethora of physiological processes, but knowledge regarding the function of these receptors in spermatozoa is limited. In the present study, we performed RNA-Seq and analyzed the expression of the all GPCRs except olfactory receptors in human spermatozoa. We revealed the expression of up to 223 different GPCR transcripts in human spermatozoa (FPKM > 0.1) and identified GPR18, a newly described cannabinoid receptor, together with GPR137 and GPR135, as one of the three most highly expressed GPCRs. To date, the expression of GPR18 was completely unknown in human spermatozoa. We confirmed GPR18 expression using RT-PCR and immuncytochemistry experiments and localized the GPR18 protein in the midpiece of human spermatozoa. Stimulation of human spermatozoa with the GPR18 ligand N-arachidonoylglycine induced the phosphorylation of 12 protein kinases, some of them are for example known to be involved in the acrosome reaction. In line with this, N-arachidonoylglycine affected the cytoskeleton by changing levels of F-actin and inducing the acrosome reaction in human spermatozoa in a concentration-dependent manner. Our results indicate that GPR18 might be involved in physiological processes of human spermatozoa, suggesting GPR18 to be a potential player in sperm physiology.

Exogenous neurotensin modulates sperm function in Japanese Black cattle

Recently, the conception rates after artificial insemination have been pointed out to decline continuously. To overcome this problem, the control of frozen and thawed sperm quality is required. However, the mechanism of bovine sperm functional regulation is still largely unknown. In mammals, the ejaculated sperm are capable of showing fertilizing ability during migration in the female reproductive organs. It is well known that these female organs secrete several factors contributing to sperm capacitation. We previously reported that neurotensin (NT) secreted from the oviduct and cumulus cells enhanced sperm capacitation and acrosome reaction in mice. In this study, we confirmed the expression of the NT receptor (NTR1) in the bovine sperm neck region and the secretion of NT in the bovine uterus and oviduct. The similar expression patterns of NT and NTR1 suggests a conserved mechanism of sperm functional regulation between mouse and cattle. Thus, we examined the effects of exogenous NT on the bovine sperm functions. First, we showed that NT induced sperm protein tyrosine phosphorylation in a dose-dependent manner, suggesting that NT enhances sperm capacitation. Second, we showed that NT induced acrosome reactions of capacitated sperm in a dose-dependent manner, suggesting that NT facilitates acrosome reaction. Finally, we used a computer-aided sperm analysis system to show that NT did not have a great effect on sperm motility. These results suggest that NT acts as a facilitator of sperm capacitation and acrosome reaction in the female reproductive tracts in cattle, highlighting the importance of NT-mediated signaling to regulate sperm functions.

BILL E. KUNKLE INTERDISCIPLINARY BEEF SYMPOSIUM: Does tall fescue toxicosis negatively impact bull growth and breeding potential?

The predominant cool-season forage in the southeastern United States is the tall fescue cultivar Kentucky 31 (KY31). Kentucky 31 possesses an endophyte (), which produces a family of toxins called ergot alkaloids. These toxins negatively affect the physiology of animals on consumption and result in the syndrome known as fescue toxicosis. Currently, the United States annually produces approximately 11.4 billion kg of beef, of which 25% originates in the southeastern region of the United States where forage systems frequently are tall fescue based. Cattle within this forage system exhibit reduced gains and reproductive performance. The result is a reduction in the nation's beef supply with annual revenue losses recently estimated at approximately US$1 billion. Our hypothesis is that exposure to these ergot alkaloids in conjunction with limited availability of nutrients decreases bull semen quality and fertility. Although the literature is clear that these toxins affect BW, body temperature, blood flow, hair growth, and female reproduction in cattle, their effect on bull reproduction and the mechanisms through which the toxins act are not well defined. Six studies published from 2004 to 2015 assessed bull growth, body composition, and semen quality of young beef bulls exposed to ergot alkaloids. If semen quality or fertility is altered, the mechanisms involved may be either direct effects of ergot alkaloids through neurotransmitter receptors or indirect effects such as inhibiting the release of prolactin (PRL). The possible effects of ergot alkaloids or PRL require establishing the presence or absence of dopamine, adrenergic, serotonin, or PRL receptors in the testis, epididymis, and sperm cell of the bull. The objective of this review is to relate our findings to the few previous studies conducted that evaluated the impact of fescue toxicosis on bull reproduction and to propose possible mechanisms of action for lowered semen quality.

Multigenerational and transgenerational inheritance of drug exposure: The effects of alcohol, opiates, cocaine, marijuana, and nicotine

Familial inheritance of drug abuse is composed of both genetic and environmental factors. Additionally, epigenetic transgenerational inheritance may provide a means by which parental drug use can influence several generations of offspring. Recent evidence suggests that parental drug exposure produces behavioral, biochemical, and neuroanatomical changes in future generations. The focus of this review is to discuss these multigenerational and transgenerational phenotypes in the offspring of animals exposed to drugs of abuse. Specifically, changes found following the administration of alcohol, opioids, cocaine, marijuana, and nicotine will be discussed. In addition, epigenetic modifications to the genome following administration of these drugs will be detailed as well as their potential for transmission to the next generation.

Presence and function of dopamine transporter (DAT) in stallion sperm: dopamine modulates sperm motility and acrosomal integrity

Dopamine is a catecholamine with multiple physiological functions, playing a key role in nervous system; however its participation in reproductive processes and sperm physiology is controversial. High dopamine concentrations have been reported in different portions of the feminine and masculine reproductive tract, although the role fulfilled by this catecholamine in reproductive physiology is as yet unknown. We have previously shown that dopamine type 2 receptor is functional in boar sperm, suggesting that dopamine acts as a physiological modulator of sperm viability, capacitation and motility. In the present study, using immunodetection methods, we revealed the presence of several proteins important for the dopamine uptake and signalling in mammalian sperm, specifically monoamine transporters as dopamine (DAT), serotonin (SERT) and norepinephrine (NET) transporters in equine sperm. We also demonstrated for the first time in equine sperm a functional dopamine transporter using 4-[4-(Dimethylamino)styryl]-N-methylpyridinium iodide (ASP⁺), as substrate. In addition, we also showed that dopamine (1 mM) treatment in vitro, does not affect sperm viability but decreases total and progressive sperm motility. This effect is reversed by blocking the dopamine transporter with the selective inhibitor vanoxerine (GBR12909) and non-selective inhibitors of dopamine reuptake such as nomifensine and bupropion. The effect of dopamine in sperm physiology was evaluated and we demonstrated that acrosome integrity and thyrosine phosphorylation in equine sperm is significantly reduced at high concentrations of this catecholamine. In summary, our results revealed the presence of monoamine transporter DAT, NET and SERT in equine sperm, and that the dopamine uptake by DAT can regulate sperm function, specifically acrosomal integrity and sperm motility.

Use of hypometabolic TRIS extenders and high cooling rate refrigeration for cryopreservation of stallion sperm: presence and sensitivity of 5' AMP-activated protein kinase (AMPK)

This study evaluated the effect of the use of hypometabolic TRIS extenders in the presence or the absence of AMPK activators as well as the utilization of high cooling rates in the refrigeration step on the freezability of stallion sperm. Twelve ejaculates were cryopreserved using Botucrio® as a control extender and a basic TRIS extender (HM-0) separately supplemented with 10 mM metformin, 2mM 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), 2 mM Adenosine monophosphate (AMP), 40 μM compound C AMPK inhibitor or 2 mM AMP+40 μM compound C. Our results showed that the utilization of a hypometabolic TRIS extender supplemented or not with AMP or metformin significantly improves stallion sperm freezability when compared with a commercial extender. Additionally, high cooling rates do not affect stallion sperm quality after cooling and post-thawing. Finally, stallion spermatozoa present several putative AMPK sperm isoforms that do not seem to respond to classical activators, but do respond to the Compound C inhibitor.

Neurotensin enhances sperm capacitation and acrosome reaction in mice

Neurotensin (NT) has multiple functions, ranging from acting as a neurotransmitter to regulating intestinal movement. However, its function in reproductive physiology is unknown. Here, we confirmed the expression and localization of NT receptors (NTR1) in mouse epididymal spermatozoa and investigated the effect of NT on sperm function. Sperm protein tyrosine phosphorylation, one of the indices of sperm capacitation, was facilitated dose-dependently by NT administration. In addition, the acrosome reaction was promoted in capacitated spermatozoa, and addition of a selective antagonist of NTR1 and NTR2 blocked the induction. Furthermore, intracellular calcium mobilization by NT addition was observed. This showed that NT was an accelerator of sperm function via its functional receptors. The presence of NT was confirmed by immunohistochemistry and its localization was observed in epithelia of the uterus and oviduct isthmus and ampulla, which correspond to the fertilization route of spermatozoa. The NT mRNA level in ovulated cumulus cell was remarkably increased by treatment with human chorionic gonadotropin (hCG). Using an in vitro maturation model, we analyzed the effects of FSH, epidermal growth factor (EGF), estradiol, and progesterone in NT production in cumulus cells. We found that FSH and EGF upregulated NT release and mRNA expression. Both FSH- and EGF-induced upregulation were inhibited by U0126, an MAPK kinase inhibitor, indicating that FSH and EGF regulate NT expression via a MAPK-dependent pathway. This evidence suggests that NT can act as a promoter of sperm capacitation and the acrosome reaction in the female reproductive tract.

AMP-activated kinase, AMPK, is involved in the maintenance of plasma membrane organization in boar spermatozoa

Spermatozoa undergo energy- and metabolism-dependent processes to successfully fertilize the oocyte. AMP-activated protein kinase, AMPK, is a sensor of cell energy. We recently showed that AMPK controls spermatozoa motility. Our aims are i) to investigate the intracellular localization of AMPK in boar spermatozoa by immunofluorescence, ii) to study whether AMPK plays a role in other relevant processes of spermatozoa: mitochondrial membrane potential (∆Ψm), plasma membrane lipid disorganization, outward phosphatidylserine (PS) exposure, acrosome integrity and induced-acrosome reaction by flow cytometry and iii) to investigate intracellular AMPK pathways by western blot. Spermatozoa were incubated under different conditions in the presence or absence of compound C (CC, 30μM), an AMPK inhibitor and/or cAMP analog 8Br-cAMP. AMPKα protein is expressed at the entire acrosome and at the midpiece of spermatozoa flagellum, whereas phospho-Thr(172)-AMPK is specifically localized at the apical part of acrosome and at flagellum midpiece. CC treatment rapidly confers head-to-head aggregation-promoting property to spermatozoa. Long term AMPK inhibition in spermatozoa incubated in TCM significantly reduces high ∆Ψm. Moreover, AMPK inhibition significantly induces plasma membrane lipid disorganization and simultaneously reduces outward PS translocation at plasma membrane in a time-dependent manner. Acrosomal integrity in TCM is significantly enhanced when AMPK is inhibited. However, neither acrosome reaction nor membrane lipid disorganization induced by ionophore A23187 are affected by CC. AMPK phosphorylation is potently stimulated upon PKA activation in spermatozoa. This work suggests that AMPK, lying downstream of PKA, regulates at different levels mammalian spermatozoa membrane function.

A chemical screen identifies class a g-protein coupled receptors as regulators of cilia

Normal cilia length and motility are critical for proper cellular function. Prior studies of the regulation of ciliary structure and length have primarily focused on the intraflagellar transport machinery and motor proteins required for ciliary assembly and disassembly. However, several mutants with abnormal length flagella highlight the importance of signaling proteins as well. In this study, an unbiased chemical screen was performed to uncover signaling pathways that are critical for ciliogenesis and length regulation using flagella of the green alga Chlamydomonas reinhardtii as a model. The annotated Sigma LOPAC1280 chemical library was screened for effects on flagellar length, motility, and severing as well as cell viability. Assay data were clustered to identify pathways regulating flagella. The most frequent target found to be involved in flagellar length regulation was the family of dopamine binding G-protein coupled receptors (GPCRs). In mammalian cells, cilium length could indeed be altered with expression of the dopamine D1 receptor. Our screen thus reveals signaling pathways that are potentially critical for ciliary formation, resorption, and length maintenance, which represent candidate targets for therapeutic intervention of disorders involving ciliary malformation and malfunction.

Impact of 2 doses of clorgyline on the rat preimplantation embryo development and the monoamine levels in urine

We have evaluated the impact of chronic administration of clorgyline, a potent monoamine oxidase A inhibitor and a former antidepressant, on the preimplantation embryo development in Wistar rats. Females were injected intraperitoneally daily for 30 days with saline (control animals), or with a low-dose clorgyline (LDC, 0.1 mg/kg per d) or with a high-dose clorgyline (HDC, 1 mg/kg per d). Embryos were isolated on day 5 of pregnancy and urine was collected by puncture of the urinary bladder. The number of embryos per female did not differ between experimental groups and control, but we have recorded a decreased number of embryos in HDC group compared to LDC (P < .05). We have found that LDC significantly reduced the presence of healthy embryos and increased the presence of the degenerated embryos (P < .001). The administration of the LDC resulted in the lowest cell number in blastocysts. We have observed significantly increased serotonin levels in HDC group compared to both control (P < .05) and LDC animals (P < .01). Norepinephrine (NE) levels in both experimental groups were significantly elevated compared to controls. Dopamine levels did not differ between groups (P > .05). We speculate that lesser negative effect of HDC compared to LDC on the preimplantation embryo development could be the consequence of the lower NE levels and/or elevated serotonin levels. Potential mechanisms mediating clorgyline-induced impaired preimplantation embryo development are proposed.