Effects of nicotine on porcine pre-pupertal sertoli cells: An in vitro study

Porcine reproductive and respiratory syndrome virus infects the reproductive system of male piglets and impairs development of the blood-testis barrier

Porcine reproductive and respiratory syndrome virus (PRRSV) causes a highly contagious disease that threatens the global swine industry. Recent studies have focused on the damage that PRRSV causes to the reproductive system of male pigs, although pathological research is lacking. Therefore, we examined the pathogenic mechanisms in male piglets infected with PRRSV. Gross and histopathological changes indicated that PRRSV affected the entire reproductive system, as confirmed via immunohistochemical analysis. PRRSV infected Sertoli cells and spermatogonia. To test the new hypothesis that PRRSV infection in piglets impairs blood - testis barrier (BTB) development, we investigated the pathology of PRRSV damage in the BTB. PRRSV infection significantly decreased the quantity and proliferative capacity of Sertoli cells constituting the BTB. Zonula occludens-1 and β-catenin were downregulated in cell - cell junctions. Transcriptome analysis revealed that several crucial genes and signalling pathways involved in the growth and development of Leydig cells, Sertoli cells, and tight junctions in the testes were downregulated. Apoptosis, necroptosis, inflammatory, and oxidative stress-related pathways were activated, whereas hormone secretion-related pathways were inhibited. Many Sertoli cells and spermatogonia underwent apoptosis during early differentiation. Infected piglets exhibited disrupted androgen secretion, leading to significantly reduced testosterone and anti-Müllerian hormone levels. A cytokine storm occurred, notably upregulating cytokines such as tumour necrosis factor-α and interleukin-6. Markers of oxidative-stress damage (i.e. H2O2, malondialdehyde, and glutathione) were upregulated, whereas antioxidant-enzyme activities (i.e. superoxide dismutase, total antioxidant capacity, and catalase) were downregulated. Our results demonstrated that PRRSV infected multiple organs in the male reproductive system, which impaired growth in the BTB.

The Smoky Impact of Nicotinic Acetylcholine Receptors on Testicular Function

Smoking habits (from classic cigarettes to e-cigarettes and heated tobacco) are a relatively common finding in the medical histories of couples referred to fertility centers. Tobacco smoke and e-cigarettes may deliver many substances with known harmful effects on both general and reproductive health, including nicotine. Nicotinic Acetylcholine receptors (nAChRs) form a heterogeneous family of ion channels that are differently expressed in different tissues. According to the homomeric or heteromeric combination of at least five different subunits (named from α to ε), they have peculiar pharmacological and biophysical properties. nAChRs respond to the neurotransmitter acetylcholine, which influences a number of physiological functions not restricted to neurons and plays an important role in the structure and function of non-neuronal tissues such as the testis. nAChRs are also the target of Nicotine, the active element responsible for tobacco addiction. This review summarizes recent findings on the involvement of nAChRs in testicular physiology, highlighting the effects of nicotine exposure observed in animal studies and clinical settings. We will discuss the latest data on fertility outcomes and the implications for understanding nAChR functions in reproductive health.

Effects and Mechanisms Activated by Treatment with Cationic, Anionic and Zwitterionic Liposomes on an In Vitro Model of Porcine Pre-Pubertal Sertoli Cells

Liposomes have been successfully used as drug-delivery vehicles, but there are no clinical studies on improved fertility and the few reported experimental studies have been performed in animal models far from humans. The aim of this paper was to study the effects of treatment with cationic, anionic and zwitterionic liposomes on our superior mammalian model of porcine prepubertal Sertoli cells (SCs) to find a carrier of in vitro test drugs for SCs. Porcine pre-pubertal SCs cultures were incubated with different liposomes. Viability, apoptosis/necrosis status (Annexin-V/Propidium iodide assay), immunolocalisation of β-actin, vimentin, the phosphorylated form of AMP-activated protein Kinase (AMPK)α and cell ultrastructure (Transmission Electron Microscopy, TEM) were analysed. Zwitterionic liposomes did not determine changes in the cell cytoplasm. The incubation with anionic and cationic liposomes modified the distribution of actin and vimentin filaments and increased the levels of the phosphorylated form of AMPKα. The Annexin/Propidium Iodide assay suggested an increase in apoptosis. TEM analysis highlighted a cytoplasmic vacuolisation. In conclusion, these preliminary data indicated that zwitterionic liposomes were the best carrier to use in an in vitro study of SCs to understand the effects of molecules or drugs that could have a clinical application in the treatment of certain forms of male infertility.

Zinc restores functionality in porcine prepubertal Sertoli cells exposed to subtoxic cadmium concentration via regulating the Nrf2 signaling pathway

INTRODUCTION

Among substances released into the environment by anthropogenic activities, the heavy metal cadmium (Cd) is known to induce severe testicular injury causing male subfertility/infertility. Zinc (Zn) is another heavy metal that, unlike Cd, is physiologically present in the testis, being essential for spermatogenesis. We aimed to examine the possibility that 50 µM ZnCl₂ could counteract the toxic effects induced by Cd in an in vitro model of porcine prepubertal Sertoli cells (SCs) exposed to both subtoxic (5 μM) and toxic (10 μM) concentrations of CdCl₂ for 48 h.

MATERIALS AND METHODS

Apoptosis, cell cycle, and cell functionality were assessed. The gene expression of Nrf2 and its downstream antioxidant enzymes, ERK1/2, and AKT kinase signaling pathways were evaluated.

MATERIALS AND RESULTS

We found that Zn, in co-treatment with subtoxic and toxic Cd concentration, increased the number of metabolically active SCs compared to Cd exposure alone but restored SC functionality only in co-treatment with subtoxic Cd concentration with respect to subtoxic Cd alone. Exposure of Cd disrupted cell cycle in SCs, and Zn co-treatment was not able to counteract this effect. Cd alone induced SC death through apoptosis and necrosis in a dose-dependent manner, and co-treatment with Zn increased the pro-apoptotic effect of Cd. Subtoxic and toxic Cd exposures activated the Nrf2 signaling pathway by increasing gene expression of Nrf2 and its downstream genes (SOD, HO-1, and GSHPx). Zn co-treatment with subtoxic Cd attenuated upregulation on the Nrf2 system, while with toxic Cd, the effect was more erratic. Studying ERK1/2 and AKT pathways as a target, we found that the phosphorylation ratio of p-ERK1/2 and p-AKT was upregulated by both subtoxic and toxic Cd exposure alone and in co-treatment with Zn.

DISCUSSION

Our results suggest that Zn could counteract Cd effects by increasing the number of metabolically active SCs, fully or partially restoring their functionality by modulating Nrf2, ERK1/2, and AKT pathways. Our SC model could be useful to study the effects of early Cd exposure on immature testis, evaluating the possible protective effects of Zn.

Resveratrol reverses male reproductive damage in rats exposed to nicotine during the intrauterine phase and breastfeeding

BACKGROUND

Nicotine leads to reproductive changes culminating in male infertility and subfertility. Resveratrol, a polyphenol, is a biological modulator. Sirtuin 1 (SIRT1) protein can positively act on male reproduction, and its expression can be affected by nicotine and modulated by resveratrol.

OBJECTIVES

The capability of resveratrol to reverse the reproductive damage in adult male offspring, which was nicotine-exposed during the intrauterine phase and breastfeeding, was investigated.

MATERIALS AND METHODS

Four groups were established with male offspring born from nicotine-exposed and non-exposed rat dams during pregnancy and lactation. Forty-eight male Wistar rats were distributed into four groups: sham control (SC), resveratrol (R), nicotine (N), and nicotine + resveratrol (NR). Rat dams of the N and NR offspring were exposed to nicotine (2 mg/kg/day) during pregnancy and lactation using a subcutaneously implanted minipump. The offspring of the R and NR groups received resveratrol (300 mg/kg of body weight, gavage) for 63 days from puberty. At 114 days of age, the male rats were euthanized.

RESULTS

Nicotine did not alter the body weight, biometry of reproductive organs, or quantitative sperm parameters of adult offspring but caused an evident worsening of all sperm qualitative parameters studied. Daily treatment with resveratrol from puberty up to adulthood improved all qualitative sperm parameters significantly, leading some of them close to the control values. Resveratrol also improved the morphological integrity and expression of SIRT1 in the seminiferous epithelium of nicotine-exposed offspring.

CONCLUSION AND DISCUSSION

Resveratrol reversed the male reproductive damage caused by nicotine. Nicotine crosses the blood-placental membrane and is present in the breast milk of mothers who smoke. Resveratrol restored the altered reproductive parameters in the male adult offspring that were nicotine-exposed during intrauterine life and breastfeeding. The epigenetic modulating action of resveratrol can be involved in this nicotine damage reversion. Resveratrol may be a promising candidate to be investigated regarding the adjuvant strategies in the treatment of male infertility.

Effects of Titanium Dioxide Nanoparticles on Porcine Prepubertal Sertoli Cells: An "In Vitro" Study

The increasing use of nanomaterials in a variety of industrial, commercial, medical products, and their environmental spreading has raised concerns regarding their potential toxicity on human health. Titanium dioxide nanoparticles (TiO2 NPs) represent one of the most commonly used nanoparticles. Emerging evidence suggested that exposure to TiO2 NPs induced reproductive toxicity in male animals. In this in vitro study, porcine prepubertal Sertoli cells (SCs) have undergone acute (24 h) and chronic (from 1 up to 3 weeks) exposures at both subtoxic (5 µg/ml) and toxic (100 µg/ml) doses of TiO2 NPs. After performing synthesis and characterization of nanoparticles, we focused on SCs morphological/ultrastructural analysis, apoptosis, and functionality (AMH, inhibin B), ROS production and oxidative DNA damage, gene expression of antioxidant enzymes, proinflammatory/immunomodulatory cytokines, and MAPK kinase signaling pathway. We found that 5 µg/ml TiO2 NPs did not induce substantial morphological changes overtime, but ultrastructural alterations appeared at the third week. Conversely, SCs exposed to 100 µg/ml TiO2 NPs throughout the whole experiment showed morphological and ultrastructural modifications. TiO2 NPs exposure, at each concentration, induced the activation of caspase-3 at the first and second week. AMH and inhibin B gene expression significantly decreased up to the third week at both concentrations of nanoparticles. The toxic dose of TiO2 NPs induced a marked increase of intracellular ROS and DNA damage at all exposure times. At both concentrations, the increased gene expression of antioxidant enzymes such as SOD and HO-1 was observed whereas, at the toxic dose, a clear proinflammatory stress was evaluated along with the steady increase in the gene expression of IL-1α and IL-6. At both concentrations, an increased phosphorylation ratio of p-ERK1/2 was observed up to the second week followed by the increased phosphorylation ratio of p-NF-kB in the chronic exposure. Although in vitro, this pilot study highlights the adverse effects even of subtoxic dose of TiO2 NPs on porcine prepubertal SCs functionality and viability and, more importantly, set the basis for further in vivo studies, especially in chronic exposure at subtoxic dose of TiO2 NPs, a condition closer to the human exposure to this nanoagent.

Fetal and Postnatal Nicotine Exposure Modifies Maturation of Gonocytes to Spermatogonia in Mice

Studies in laboratory animals have shown that male offspring from dams, exposed to nicotine during pregnancy and postnatal periods, show alterations in fertility, although the origin of this is still uncertain. In this study, we examined in a mouse model if the process of gonocyte maturation to spermatogonia was affected in male offspring from dams with nicotine administration during pregnancy and postnatal periods. BALB/C mice, with and without nicotine administrations in pregnancy and postnatal periods, were studied. The animals were euthanized at 3, 7, 10, 16, and 35 days postpartum (dpp). Testicular tissue samples were processed for histological, ultrastructural, and immunohistochemical studies; and testicular lipoperoxidation was determined. It was observed that in the nicotine-exposed animals, there was increased apoptosis and a reduction in the number of gonocytes that matured to spermatogonia. This gonocyte-spermatogonia maturation reduction was associated with a greater immunoreactivity to nicotinic acetylcholine receptors in the germ cells. Lipoperoxidation was similar in both groups until 16 dpp, with significant reduction at 35 dpp. Our findings suggest that nicotine intake during pregnancy and postnatal periods can affect the process of maturation of gonocytes to spermatogonia and the pool of available spermatogonia for spermatogenesis.