Potential mechanisms behind the antioxidant actions of prolactin in the retina

Retinal prolactin isoform PRLΔE1 sustains rod disease in inherited retinal degenerations

PRLΔE1, a retina-specific isoform of prolactin, is expressed in multiple and diverse forms of canine inherited retinal degeneration (IRD). We find that while PRLΔE1 expression in rods is not associated with the initial phase of disease characterized by acute photoreceptor cell death, it is associated with the protracted phase of slow cell loss. Restoration of photoreceptors to a healthy state by gene-specific replacement therapy of individual IRDs successfully suppresses PRLΔE1 expression. Moreover, short-term PRLΔE1 silencing using shRNA results in preservation of outer nuclear layer thickness, suggesting PRLΔE1 drives retinal disease. However, longer-term observations reveal off-target toxic effects of the PRLΔE1 shRNA, precluding determination of its full therapeutic potential. Future research efforts aimed at enhancing the safety and specificity of PRLΔE1-targeting strategies may identify a potential universal intervention strategy for sustaining photoreceptors during the prolonged phase of multiple IRDs.

Evaluation of oxidative stress and inflammation in patients with polycystic ovary syndrome

OBJECTIVE

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine and metabolic disorder characterized by hyperandrogenism, hyperinsulinemia, and insulin resistance. The prevalence of PCOS is increasing worldwide. Although the etiology of this disease is currently unknown, it is thought to be closely related to inflammation and oxidative stress. Our study aimed to compare patients have PCOS to healthy volunteers and assess the changes in oxidative stress and inflammatory parameters in these patients.

METHODS

Thirty patients between the ages of 18-45 diagnosed with PCOS and 30 healthy volunteers with the same demographic characteristics were included in this study. Clinical parameters were measured using immunoassays. Oxidative stress biomarkers, total oxidant (TOS), total antioxidant (TAS), total thiol (TT), and native thiol (NT) levels were measured using photometric methods according to Erel's method. The dynamic disulfide level (DIS) and oxidative stress index (OSI) were calculated using mathematical equations. Among the inflammatory parameters, values for interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were measured photometrically using commercially purchased kits.

RESULTS

Moreover, TT and NT levels were lower in patients with PCOS compared to those in the healthy group statistically significantly (P<0.001). In addition, TAS, TOS, OSI, DIS, IL-1β, IL-6, and TNF-α levels were identified to be significantly higher in the patients with PCOS than those in the healthy group (P<0.001).

CONCLUSION

Evaluation of oxidative stress and clinical parameters used in the follow-up may be beneficial for the disease.

Protective Effect of Hyperprolactinemia on Oxidative Stress in Patients with Psychotic Disorder on Atypical Antipsychotics Risperidone and Paliperidone: A Cross-Sectional Study

Several studies indicate the impact of antipsychotics like risperidone and paliperidone on oxidative stress parameters, yet data remain inconsistent. We investigated the link between these medications, hyperprolactinemia (HPRL), and oxidative stress. This study was conducted at the Psychiatry Clinic, University Clinical Center, Kragujevac, between November 2022 and August 2023. Inclusion criteria comprised diagnosed psychotic disorders from the ICD-10-based F20-F29 spectrum and clinical stability on risperidone/paliperidone for ≥12 weeks with no recent dose adjustments. Exclusion criteria included pregnancy, breastfeeding, relevant medical conditions, or co-therapy with prolactin-secreting drugs. Data encompassed drug choice, administration method, therapy duration, and daily dose. Prolactin (PRL) levels, oxidative stress parameters (TBARS, H2O2, O2-, NO2-), and antioxidant system (CAT, GSH, SOD) were assessed. Of 155 subjects, women exhibited significantly higher PRL levels (p < 0.001) and symptomatic HPRL (p < 0.001). Drug choice and regimen significantly influenced TBARS (p < 0.001), NO2- (p < 0.001), O2- (p = 0.002), CAT (p = 0.04), and GSH (p < 0.001) levels. NO2- levels were affected by drug dose (p = 0.038). TBARS (p < 0.001), O2- (p < 0.001), and SOD (p = 0.022) inversely correlated with PRL levels, suggesting PRL's protective role against oxidative stress. The female sex association with higher PRL levels implies additional factors influencing PRL's antioxidant role. Antipsychotic choice and dosage impact PRL and oxidative stress markers, necessitating further exploration.

Effect of prolactin on cytotoxicity and oxidative stress in ovine ovarian granulosa cells

Background

Prolactin (PRL) has been reported to be associated with oxidative stress, which is an important contributor leading to cell apoptosis. However, little is known about the mechanisms underlying the effects of PRL on cytotoxicity and oxidative stress in ovine ovarian granulosa cells (GCs).

Methods

Ovine ovarian GCs were treated with 0, 4, 20, 100 and 500 ng/mL of PRL. Then, the cytotoxicity, cell viability, malondialdehyde (MDA), reactive oxygen species (ROS), superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) of GCs were detected. Additionally, 500 ng/mL PRL was chosen as the high PRL concentration (HPC) due to its high cytotoxicity and oxidative stress. Proteomic and metabonomic were performed to examine the overall difference in proteins and metabolic pathways between C (control: 0 ng/mL PRL) and P groups (500 ng/mL PRL).

Results

The results indicated that GCs treated with 4 ng/mL PRL significantly decreased (P < 0.05) the cytotoxicity, ROS and MDA, increased (P < 0.05) the cell viability, SOD and T-AOC, and the GCs treated with 500 ng/mL PRL showed the opposite trend (P < 0.05). Supplementation with 500 ng/mL PRL significantly increased the proteins of MT-ND1, MAPK12, UBA52 and BCL2L1, which were enriched in ROS and mitophagy pathways. Pathway enrichment analysis showed that the pentose phosphate pathway was significantly enriched in the P group.

Conclusion

A low concentration of PRL inhibited cytotoxicity and oxidative stress. HPC induced oxidative stress in ovine ovarian GCs via the pentose phosphate pathway by modulating the associated proteins MT-ND1 in ROS pathway and UBA52, MAPK12 and BCL2L1 in mitophagy pathway, resulting in cytotoxicity.

Lactation attenuates pro-oxidant reactions in the maternal brain

Reactive oxygen species (ROS) are intimately linked to bioenergetics and redox biology, contributing to cellular functioning and physiological signaling, but also acting as toxic agents during oxidative stress. Hence, the balance between pro-oxidant reactions and the activity of antioxidant defenses sustains a basal oxidative status, controls the increase of redox signaling, and mediates potential pathological events during oxidative stress. Maternal experience, especially during nursing, requires high energetic demands and expenditure to ensure the well-being of the offspring. The mother must adapt from satisfying her own needs to additionally fulfilling those of her descendants. Oxidative stress has been proposed as one of the reproductive trade-off hallmarks. However, the oxidative shielding hypothesis has also been proposed in the context of reproduction. The reproductive experience induces a wide range of well-documented changes in the female brain, which potentially lead to protection against the enhanced oxidative activity. To date, the metabolic and cellular mechanisms that underlie lactation-induced neuroprotection against oxidants are unknown. The neuroendocrine changes in the brain of the lactating dam promote diminished propensity to excitotoxic brain injury and stress, as well as enhanced neuroprotection and plasticity. In addition to review studies on the oxidant balance due to motherhood, we included new data from our laboratory, addressing the importance of measuring pro-oxidant reactions in separated brain regions. The hippocampus of lactating rats exhibits lower levels of pro-oxidant reactions than that of virgin rats, supporting the oxidative shielding hypothesis in lactation.

β-Lactoglobulin affects the oxidative status and viability of equine endometrial progenitor cells via lncRNA-mRNA-miRNA regulatory associations

The β-lactoglobulin (β-LG) was previously characterized as a mild antioxidant modulating cell viability. However, its biological action regarding endometrial stromal cell cytophysiology and function has never been considered. In this study, we investigated the influence of β-LG on the cellular status of equine endometrial progenitor cells under oxidative stress. The study showed that β-LG decreased the intracellular accumulation of reactive oxygen species, simultaneously ameliorating cell viability and exerting an anti-apoptotic effect. However, at the transcriptional level, the reduced mRNA expression of pro-apoptotic factors (i.e. BAX and BAD) was accompanied by decreased expression of mRNA for anti-apoptotic BCL-2 and genes coding antioxidant enzymes (CAT, SOD-1, GPx). Still, we have also noted the positive effect of β-LG on the expression profile of transcripts involved in endometrial viability and receptivity, including ITGB1, ENPP3, TUNAR and miR-19b-3p. Finally, the expression of master factors of endometrial decidualization, namely prolactin and IGFBP1, was increased in response to β-LG, while non-coding RNAs (ncRNAs), that is lncRNA MALAT1 and miR-200b-3p, were upregulated. Our findings indicate a novel potential role of β-LG as a molecule regulating endometrial tissue functionality, promoting viability and normalizing the oxidative status of endometrial progenitor cells. The possible mechanism of β-LG action includes the activation of ncRNAs essential for tissue regeneration, such as lncRNA MALAT-1/TUNAR and miR-19b-3p/miR-200b-3p.

Expression of Opsin Genes in the Retina of Female and Male Three-Spined Sticklebacks Gasterosteus aculeatus L.: Effect of Freshwater Adaptation and Prolactin Administration

Color vision sensitivity is crucial for fish adaptation during migration and reproduction. Prolactin and prolactin-like hormone are important regulators in both these processes. We hypothesized that prolactin influences the color vision sensitivity during freshwater migrations in fish. We studied the effects of prolactin and freshwater adaptation during the spawning period on the expression of opsin genes (SWS1, SWS2, RH2, LWS) in the retina of female and male three-spined sticklebacks Gasterosteus aculeatus L. Expression of the prolactin gene increased in the brain of females, but not males, while expression of the prolactin-like hormone decreased in the brain of both male and female sticklebacks during freshwater adaptation. Expression of the SWS2 gene decreased in the retina of females and males during freshwater adaptation and after prolactin administration. Expression of the SWS1 gene decreased in the retina of male sticklebacks after prolactin administration, but not during freshwater adaptation. Expression of the RH2 and LWS genes did not depend on prolactin administration in male and female sticklebacks. We conclude that expression of some opsin genes in the retina of sticklebacks is regulated by prolactin and depends on sex and freshwater adaptation. This expands our knowledge of the adaptive effects of prolactin on fish during freshwater migrations.

Physicochemical, antioxidant, rheological, and sensory properties of juice produced with guava pulp and peel flour

Juice formulations containing guava pulp and different amounts (0%, 1%, 3%, and 5%) of its by-product flour (GBF) were developed and evaluated for antioxidant activity, total phenolic compounds, physicochemical, rheological, microbiological and sensorial parameters. The GBF addition to guava juice increased the acidity and altered the color and rheological parameters, especially at higher levels (3% and 5%). There was an increase in the content of dietary fiber, anthocyanins and antioxidant activity with GBF addition, but no changes occurred in the soluble solids, total phenolic compounds, and ascorbic acid content. The guava juice containing 1% GBF received better sensory scores when compared with the 3% and 5% GBF formulations. Storage at 4o C for 21 days affected most of the parameters examined, but the microbiological parameters remained stable. Shelf life of 14 days is recommended to maintain the physicochemical and antioxidants characteristics of guava juice.

Decoding signaling pathways involved in prolactin-induced neuroprotection: A review

It has been well recognized that prolactin (PRL), a pleiotropic hormone, has many functions in the brain, such as maternal behavior, neurogenesis, and neuronal plasticity, among others. Recently, it has been reported to have a significant role in neuroprotection against excitotoxicity. Glutamate excitotoxicity is a common alteration in many neurological and neurodegenerative diseases, leading to neuronal death. In this sense, several efforts have been made to decrease the progression of these pathologies. Despite various reports of PRL's neuroprotective effect against excitotoxicity, the signaling pathways that underlie this mechanism remain unclear. This review aims to describe the most recent and relevant studies on the molecular signaling pathways, particularly, PI3K/AKT, NF-κB, and JAK2/STAT5, which are currently under investigation and might be implicated in the molecular mechanisms that explain the PRL effects against excitotoxicity and neuroprotection. Remarkable neuroprotective effects of PRL might be useful in the treatment of some neurological diseases.

Short prolactin isoforms are expressed in photoreceptors of canine retinas undergoing retinal degeneration

Prolactin (PRL) hormone functions as a pleiotropic cytokine with a protective role in the retina. We recently identified by transcriptome profiling that PRL is one of the most highly upregulated mRNAs in the retinas of mutant rcd1 (PDE6B) and xlpra2 (RPGR) dogs at advanced stages of photoreceptor disease. In the present study, we have identified the expression of a short PRL isoform that lacks exon 1 in canine retinas and analyzed the time-course of expression and localization of this isoform in the retinas of these two models. Using laser capture microdissection to isolate RNA from each of the retinal cellular layers, we found by qPCR that this short PRL isoform is expressed in photoreceptors of degenerating retinas. We confirmed by in situ hybridization that its expression is localized to the outer nuclear layer and begins shortly after the onset of disease at the time of peak photoreceptor cell death in both models. PRL protein was also detected only in mutant dog retinas. Our results call for further investigations into the role of this novel PRL isoform in retinal degeneration.

Therapeutic Potential of Selenium as a Component of Preservation Solutions for Kidney Transplantation

Selenium has strong antioxidant properties and diverse effects on the immune system. The aim of the study was to analyse the protective effect of selenium as a component of a kidney preservation solution on the prevention of ischemia-reperfusion injury of nephrons. The solution was modified by the addition of Se (1 µg/L), prolactin (0.1 µg/L) and Se with prolactin (1 µg/L Se + 0.1 µg/L PRL). The study used a model for storing isolated porcine kidneys in Biolasol^® (modified Biolasol^®), which minimizes ischemia-reperfusion injury of grafts. The introduction of Se⁴⁺ ions at a dose of 1 µg/L into the Biolasol^® preservation solution in the form of Na₂SeO₃ caused an increase in the activity/concentration of the analysed biochemical parameters: aspartate transaminase, alanine transaminase, urea and protein. This suggests an adverse effect of Se⁴⁺ on nephron function during ischemia-reperfusion. The best graft protection was obtained by using Biolasol^® modified with the addition of selenium (IV) at a dose of 1 µg/L and prolactin at a concentration of 0.1 µg/L. We proposed the mechanism of prolactin action in the metabolic reduction of selenite (SO₃²⁻) during ischemia/reperfusion.

Prolactin mitigates deficiencies of retinal function associated with aging

Aging causes the progressive degeneration of retinal cells leading to the eventual loss of vision. The hormone prolactin (PRL) is a neurotrophic factor able to compensate for photoreceptor cell death and electroretinogram deficits induced by light retinal damage. Here, we used adult 4-month old and aged 20-month old pigmented mice, null or not for the PRL receptor to explore whether PRL provides trophic support against age-related retinal dysfunction. Retinal functionality, apoptosis, glia activation, and neurotrophin expression were assessed by electroretinogram, TUNEL, glial fibrillary acidic protein and ionized calcium binding adaptor molecule 1 immunohistochemistry, and real-time PCR, respectively. Lack of PRL signaling in aged mice, but not in adult mice, correlated with photosensitive retinal dysfunction, increased photoreceptor apoptosis, differential expression of proapoptotic mediators, and microglia activation. We conclude that PRL is required for maintaining retinal functionality in both female and male mice during aging and has potential therapeutic value against age-related retinal disorders.

Neuroprotective Peptides in Retinal Disease

In the pathogenesis of many disorders, neuronal death plays a key role. It is now assumed that neurodegeneration is caused by multiple and somewhat converging/overlapping death mechanisms, and that neurons are sensitive to unique death styles. In this respect, major advances in the knowledge of different types, mechanisms, and roles of neurodegeneration are crucial to restore the neuronal functions involved in neuroprotection. Several novel concepts have emerged recently, suggesting that the modulation of the neuropeptide system may provide an entirely new set of pharmacological approaches. Neuropeptides and their receptors are expressed widely in mammalian retinas, where they exert neuromodulatory functions including the processing of visual information. In multiple models of retinal diseases, different peptidergic substances play neuroprotective actions. Herein, we describe the novel advances on the protective roles of neuropeptides in the retina. In particular, we focus on the mechanisms by which peptides affect neuronal death/survival and the vascular lesions commonly associated with retinal neurodegenerative pathologies. The goal is to highlight the therapeutic potential of neuropeptide systems as neuroprotectants in retinal diseases.

The Effect of Modified Biolasol Solution on the Efficacy of Storing Isolated Porcine Kidneys

Biolasol is a newly developed solution for storing the liver, pancreas, kidneys, and heart by simple hypothermia. It exhibits high efficacy in maintaining structural and functional integrity of the graft prior to its transplantation. The solution was modified by the addition of ascorbic acid (0.088g/l) and ascorbic acid with prolactin (1 μg/l PRL + 0.088g/l vitamin C). The effectiveness of the obtained solutions in the protection of nephrons of isolated porcine kidneys was assessed based on the analysis of the activity of ALT (alanine aminotransferase), AST (aspartate aminotransferase), and LDH (lactate dehydrogenase) as well as lactate concentration determined in perfundates collected after 2 h (0' and 30' preservation) and 48 h (0' and 30' preservation) of graft storage. It has been found that the synergistic action of Biolasol components determines the integrity and stability of cell membranes, which in turn affects the proper functioning of the organ after transplantation. The addition of ascorbic acid and prolactin to Biolasol affects the maintenance of the normal cytoskeleton of the stored graft.