Role of Cholesterol, DOTAP, and DPPC in Prostasome/Spermatozoa Interaction and Fusion

Role of Redox Homeostasis in the Communication Between Brain and Liver Through Extracellular Vesicles

Extracellular vesicles (EVs) are small, membrane-bound particles secreted by cells into the extracellular environment, playing an increasingly recognized role in inter-organ communication and the regulation of various physiological processes. Regarding the redox homeostasis context, EVs play a pivotal role in propagating and mitigating oxidative stress signals across different organs. Cells under oxidative stress release EVs containing signaling molecules that can influence the redox status of distant cells and tissues. EVs are starting to be recognized as contributors to brain-liver communication. Therefore, in this review, we show how redox imbalance can affect the release of EVs in the brain and liver. We propose EVs as mediators of redox homeostasis in the brain-liver axis.

Extracellular vesicle research in reproductive science- Paving the way for clinical achievements

Mammalian conception involves a multitude of reciprocal interactions via a molecular dialogue between mother and conceptus. Extracellular vesicles (EVs) are secreted membrane-encapsulated particles that mediate cell-to-cell communication in various contexts. EVs, which are present in seminal, follicular, oviductal, and endometrial fluids, as well as in embryo secretions, carry molecular constituents that impact gamete maturation, fertilization, early embryo development, and embryo-maternal communication. The distribution, concentration, and molecular cargo of EVs are regulated by steroid hormones and the health status of the tissue of origin, and thus are influenced by menstrual phase, stage of conception, and the presence of infertility-associated diseases. EVs have been recognized as a novel source of biomarkers and potential reproductive medicine therapeutics, particularly for assisted reproductive technology (ART). There are still many technological and scientific hindrances to be overcome before EVs can be used in clinical diagnostic and therapeutic ART applications. Issues to be resolved include the lack of standardized measurement protocols and an absence of absolute EV quantification technologies. Additionally, clinically suitable and robust EV isolation methods have yet to be developed. In this review, we provide an overview of EV-mediated interactions during the early stages of reproduction from gamete maturation to embryo implantation and then outline the technological progress that must be made for EV applications to be translated to clinical settings.

Evidence that extrapancreatic insulin production is involved in the mediation of sperm survival

Evidence is presented for expression of the insulin receptor on the surface of mammalian spermatozoa as well as transcripts for the receptor substrate adaptor proteins (IRS1-4) needed to mediate insulin action. Exposure to this hormone resulted in insulin receptor phosphorylation (pTyr972), activation of AKT (pSer473) and the stimulation of sperm motility. Intriguingly, the male germ line is also shown to be capable of generating insulin, possessing the relevant mRNA transcript and expressing strong immunocytochemical signals for both insulin and C-peptide. Insulin could be released from the spermatozoa by sonication in a concentration-dependent manner but was not secreted in response to glucose, fructose or stimulation with progesterone. However, insulin release could be induced by factors present in human uterine lavages. Furthermore, the endometrium was also shown to possess the machinery for insulin production and action (mRNA, insulin, C-peptide, proprotein convertase and insulin receptor), releasing insulin into the uterine lumen prior to ovulation. These studies emphasize the fundamental importance of extra-pancreatic insulin in regulating the reproductive process, particularly in the support of spermatozoa on their perilous voyage to the site of fertilization.

Desmosterol, the main sterol in rabbit semen: distribution among semen subfractions and its role in the in vitro spermatozoa acrosome reaction and motility

Sterols are essential components of the cell membrane lipid bilayer that include molecules such as cholesterol and desmosterol, which are significantly found in the spermatozoa of several animal species. However, the presence of desmosterol in rabbit semen has never been investigated. The aims of this study were to characterize the sterol composition of subfractions of ejaculated rabbit semen and evaluate the in vitro effects of sterol on the spermatozoa acrosome reaction and motility. Two sterols, occurring prevalently in the free form (94.3%), were identified in whole semen collected from 10 fertile New Zealand White rabbits, specifically desmosterol (58.5% of total sterols) and cholesterol (35.9% of total sterols). Desmosterol was the predominant sterol found in all subfractions of rabbit semen, varying from 56.7% (in the prostatic secretory granules, PSGs) to 63.8% (in the seminal plasma). Spermatozoa contained an intermediate proportion of desmosterol (59.8%), which was asymmetrically distributed between the heads (52.0% of the total content of sterols) and the tails (81.8%). Results showed that both desmosterol and cholesterol can be transferred from the PSGs to the spermatozoa and are equally effective in inhibiting in vitro spermatozoa capacitation at a concentration higher than 1 mg L(-1). In contrast, neither desmosterol nor cholesterol had a significant effect on spermatozoa motility. Thus, it was concluded that, the various fractions of rabbit seminal fluid differ from each other in sterol composition and quantity, probably due to their different functional properties, and these fractions may undergo significant sterol changes depending on the stage of spermatozoa capacitation.

In vitro antioxidant activity of the prostatic secretory granules in rabbit semen after exposure to organic peroxides

BACKGROUND

The prostate gland of rabbits produces numerous granules, which are specifically implicated in the inhibition of sperm capacitation during the first hours after mating. These granules are rich in vitamin E, but their role in the antioxidant protection of rabbit sperm has not been studied.

AIM OF STUDY

The objectives of this study were to investigate whether the prostatic secretory granules (PSGs) could prevent sperm induced-lipid peroxidation and to verify a potential involvement of tocopherols from the PSGs to the sperm.

METHODS

Washed sperm samples taken from eighteen White New Zealand rabbits were either incubated with tert-butyl-hydroperoxide (t-BHP, an oxidative stressor) or with buffered Tyrode's medium for 1 hour. The same number of sperm samples that contained PSGs were subjected to the previously mentioned treatments and thiobarbituric acid reactive substances (TBARS), vitamin E compounds and the acrosome status were assessed.

RESULTS

The incubation of the sperm with t-BHP resulted in a noticeable production of TBARS (0.38 vs. 0.22 nmol/10(7) cells) and an associated decrease of alpha-tocopherol (alpha-T, 72.3 vs. 103.2 nmol/10(8) cells) with respect to the sperm samples containing PSGs. The sperm incubated with the PSGs had a higher amount of alpha-T compared to the control (292.2 vs. 251.0 nmol/10(8) cells). The acrosome status was not affected by the occurrence of the organic peroxide in the medium and the amount of capacitated sperm was lower when the PSGs were also present.

CONCLUSIONS

Overall, these results suggest that the PSGs may represent a source of protection for rabbit sperm against in vitro oxidative stress by supplying the sperm with endogenous alpha-T. This mechanism could be in part involved in the inhibition of sperm capacitation by the granules.

In vivo imaging of in situ motility of fresh and liquid stored ram spermatozoa in the ewe genital tract

The fertility of ram semen after cervical insemination is substantially reduced by 24 h of storage in liquid form. The effects of liquid storage on the transit of ram spermatozoa in the ewe genital tract was investigated using a new procedure allowing direct observation of the spermatozoa in the genital tract. Ejaculated ram spermatozoa were double labeled with R18 and MitoTracker Green FM, and used to inseminate ewes in estrus either cervically through the vagina or laparoscopically into the base of the uterine horns. Four hours after insemination, the spermatozoa were directly observedin situusing fibered confocal fluorescence microscopy in the base, middle and tip of the uterine horns, the utero-tubal junction (UTJ) and the oviduct. The high resolution video images obtained with this technique allowed determination of the distribution of spermatozoa and individual motility in the lumen of the ewe's genital tract. The results showed a gradient of increasing concentration of spermatozoa from the base of the uterus to the UTJ 4 h after intra-uterine insemination into the base of the horns. The UTJ was shown to be a storage region for spermatozoa before their transfer to the oviduct. Thein vitrostorage of spermatozoa in liquid form decreased their migration through the cervix and reduced the proportion of motile spermatozoa and their straight line velocity at the UTJ and their transit into the oviduct.

Co-delivery of siRNA and an anticancer drug for treatment of multidrug-resistant cancer

AIMS

To develop a novel nanomedicine approach for the treatment of multidrug-resistant (MDR) cancer by combining an anticancer drug and suppressors of cellular resistance within one multifunctional nanocarrier-based delivery system (NDS).

MATERIALS & METHODS

The NDS consisted of cationic liposomes (carrier, 100-140 nm), doxorubicin (DOX, anticancer drug), siRNA targeted to MRP1 and BCL2 mRNA (suppressors of pump and nonpump cellular-resistance, respectively). The resulting approximately 500 nm complex has a zeta potential of +4 mV.

RESULTS & DISCUSSION

The NDS provides an effective co-delivery of DOX and siRNA as well as cell-death induction and suppression of cellular resistance in MDR lung cancer cells.

CONCLUSION

We demonstrate NDS-enhanced efficiency of chemotherapy to a level that cannot be achieved by applying its components separately.

New ways of imaging uptake and intracellular fate of liposomal drug carrier systems inside individual cells, based on Raman microscopy

Recent developments, combining Raman spectroscopy with optical microscopy, provide a new noninvasive technique to assess and image cellular processes. Of particular interest are the uptake mechanisms of various cytologically active compounds. In order to distinguish the species of interest from their cellular environment spectroscopically, compounds may be labeled with deuterium. Here, we apply Raman microspectroscopy to follow the uptake of liposomal drug carrier systems that have been introduced to deliver biologically active compounds to their site of action within human breast adenocarcinoma MCF-7 cells. The distribution patterns of liposomes and liposomes surface-modified with a cell-penetrating peptide (TAT-peptide, TATp) have been imaged over time. The spectroscopic information obtained provides a clear evidence for variable rates, as well as different efficiencies of liposome uptake depending on their surface properties. Depending on the experimental setup, the technique may be applied to fixed or living cell organisms.