Effects of Cistanche deserticola on behavior and signs of cataract and retinopathy in senescence-accelerated OXYS rats

Shenqisherong pill ameliorates neuronal apoptosis by inhibiting the JNK/caspase-3 signaling pathway in a rat model of cervical cord compression

ETHNOPHARMACOLOGICAL RELEVANCE

The Shenqisherong (SQSR) pill is an empirical prescription of traditional Chinese medicine (TCM), which originated from the National Chinese Medical Science Master, Shi Qi. It has been widely used in the treatment of cervical spondylotic myelopathy (CSM) and promote the recovery of spinal cord function, but underlying molecular mechanism remains unclear.

AIM OF THE STUDY

The objective of this study was to confirm the neuroprotective effects of the SQSR pill.

MATERIALS AND METHODS

A rat model of chronic compression at double-level cervical cord was used in vivo. The protective role of SQSR pill on CSM rats was measured by Basso, Beattie, and Bresnahan (BBB) locomotor scale, inclined plane test, forelimb grip strength assessment, hindlimb pain threshold assessment, and gait analysis. The levels of reactive oxygen species (ROS) were examined by Dihydroethidium (DHE) staining and 2',7'-Dichlorofluorescein (DCF) assay, and apoptosis was detected by TdT-mediated dUTP nick-end labeling (TUNEL) assay. The expression of apoptosis proteins was evaluated by immunofluorescence staining and Western blot.

RESULTS

SQSR pill could facilitate locomotor function recovery in rats with chronic cervical cord compression, reduce local ROS in the spinal cord and downregulate the c-Jun-N-terminal kinase (JNK)/caspase-3 signaling pathway. In addition, the SQSR pill could protect primary rat cortical neurons from glutamate-treated toxicity in vitro by reducing the ROS and downregulating the phosphorylation of JNK and its downstream factors related to neuronal apoptosis meditated by the caspase cascade. Then, the neuroprotective effect was counteracted by a JNK activator.

CONCLUSIONS

Together, SQSR pill could ameliorate neuronal apoptosis by restraining ROS accumulation and inhibiting the JNK/caspase-3 signaling pathway, indicating that SQSR pill could be a candidate drug for CSM.

Cellular senescence and ophthalmic diseases: narrative review

PURPOSE

Cellular senescence is a state of permanent growth arrest whereby a cell reaches its replicative limit. However, senescence can also be triggered prematurely in certain stressors including radiation, oxidative stress, and chemotherapy. This stress-induced senescence has been studied in the context of promoting inflammation, tumor development, and several chronic degenerative diseases of aging. Emerging research has elucidated the role of senescence in various ocular diseases.

METHODS

The literature search was performed using PubMed with using the query (senescence OR aging) AND (eye disease OR ocular disease OR ophthalmic disease OR cornea OR glaucoma OR cataract OR retina) on October 20th, 2022. No time restriction was proposed. Articles were excluded if they were not referenced in English.

RESULTS

Overall, 51 articles regarding senescence and ocular diseases were found and summarized in this study. Several signaling pathways have been implicated in the development of senescence. Currently, senescence has been linked to various corneal and retinal pathologies, as well as cataract and glaucoma. Given the number of pathologies, senolytics, which are small molecules with the ability to selective targeting of senescent cells, can be used as therapeutic or prophylactic agents.

CONCLUSIONS

Senescence has been shown to underlie the pathogenesis of numerous ocular diseases. The overall literature on senescence and ocular disease is growing rapidly. There is an ongoing debate whether or not cellular senescence detected in experiments contributes in a significant way to diseases. Research on understanding the mechanism of senescence from ocular cells and tissues is just beginning. Multiple animal models are required to test potential senolytics. Currently, no studies exist to date which have demonstrated the benefits of senolytic therapies in human studies.

The use of medicinal plants in common ophthalmic disorders: A systematic review with meta-analysis

Purpose

This study aimed to assess and compile the available research articles about medicinal plants used for ocular diseases.

Principal results

A total of 2949 articles were retrieved, 35 full-text articles were assessed for eligibility, and seven studies (4 observational and three experimental) with low to moderate quality were eligible and involved in the systematic review, with a total of 600 plants from 4 countries. Among the 600 plants, only 24 (4%) were used to assess the status. Both the fixed and random models of the studies showed that the included studies tended to predict the results for the observational studies (OR = 0.062, CI = 0.043-0.090 OR = 0.039, CI = 0.012-0.122) for different plants used for ocular diseases. High heterogeneity (estimated as I² = 87.078, Tau² = 1.161 and Q-value = 23.217 with a p-value of 0.000), while for experimental studies (I² = 94.928, Tau² = 23.211 and Q-value = 39.434 with a p-value of 0.000) and publication bias were reported.

Conclusion

Few articles representing approximately 600 plants of low to moderate quality reported using medicinal plants for ocular diseases. The meta-analysis confirmed the systematic review findings regarding the plants' traditional use with high heterogeneity and publication bias. A considerable gap was proven in the use of medicinal plants in ocular diseases requiring intensive research.

Metabolome profiling and molecular docking analysis revealed the metabolic differences and potential pharmacological mechanisms of the inflorescence and succulent stem of Cistanche deserticola

Cistanche deserticola is an endangered plant used for medicine and food. Our purpose is to explore the differences in metabolism between inflorescences in non-medicinal parts and succulent stems in medicinal parts in order to strengthen the application and development of the non-medicinal parts of C. deserticola. We performed metabolomics analysis through LC-ESI-MS/MS on the inflorescences and succulent stems of three ecotypes (saline-alkali land, grassland and sandy land) of C. deserticola. A total of 391 common metabolites in six groups were identified, of which isorhamnetin O-hexoside (inflorescence) and rosinidin O-hexoside (succulent stems) can be used as chemical markers to distinguish succulent stems and inflorescences. Comparing the metabolic differences of three ecotypes, we found that most of the different metabolites related to salt-alkali stress were flavonoids. In particular, we mapped the biosynthetic pathway of phenylethanoid glycosides (PhGs) and showed the metabolic differences in the six groups. To better understand the pharmacodynamic mechanisms and targets of C. deserticola, we screened 88 chemical components and 15 potential disease targets through molecular docking. The active ingredients of C. deserticola have a remarkable docking effect on the targets of aging diseases such as osteoporosis, vascular disease and atherosclerosis. To explore the use value of inflorescence, we analyzed the molecular docking of the unique flavonoid metabolites in inflorescence with inflammation targets. The results showed that chrysoeriol and cynaroside had higher scores for inflammation targets. This study provides a scientific basis for the discovery and industrialization of the resource value of the non-medicinal parts of C. deserticola, and the realization of the sustainable development of C. deserticola. It also provides a novel strategy for exploring indications of Chinese herb.

Flow chart for exploring the metabolic and pharmacological characteristics of different parts of Cistanche deserticola.

Cistanches Herba, from an endangered species to a big brand of Chinese medicine

Cistanches Herba (CH, Chinese name: Roucongrong), is a very precious, tonic Chinese medicine. Cistanche deserticola and Cistanche tubulosa are the two commonly used species and authenticated in Chinese Pharmacopoeia. Due to the parasitic nature of Cistanche plants, the wild source was once endangered and listed in the Appendix II of Convention on International Trade in Endangered Species of Wild Fauna and Flora. However, after continuously struggling in the past decades, CH has grown up to a big brand of Chinese medicine featured with the cultivation area as 1.26 million mu, the annual output as 6000 tons, and the related industrial output value as more than 20 billion China Yuan, attributing to large-scale cultivation and in-depth phytochemical and pharmacological investigations. Noteworthily, great achievements have reached concerning the research and development of relevant products, such as modern drugs, traditional Chinese medicine prescriptions, and dietary supplements. The current review summarizes the research progresses concerning the distribution and cultivation, phytochemistry, pharmacology, metabolism and product development of CH in the past decades, and the emerging challenges and developing prospects are discussed as well.

Cistanches Herba: An overview of its chemistry, pharmacology, and pharmacokinetics property

ETHNOPHARMACOLOGICAL RELEVANCE

Cistanches Herba is an Orobanchaceae parasitic plant. As a commonly used Traditional Chinese Medicine (TCM), its traditional functions include treating kidney deficiency, impotence, female infertility and senile constipation. Chemical analysis of Cistanches Herba revealed that phenylethanoid glycosides, iridoids, lignans, oligosaccharides, and polysaccharides were the main constituents. Pharmacological studies demonstrated that Cistanches Herba exhibited neuroprotective, immunomodulatory, hormonal balancing, anti-fatigue, anti-inflammatory, hepatoprotection, anti-oxidative, anti-bacterial, anti-viral, and anti-tumor effects, etc. The aim of this review is to provide updated, comprehensive and categorized information on the phytochemistry, pharmacological research and pharmacokinetics studies of the major constituents of Cistanches Herba.

MATERIALS AND METHODS

The literature search was conducted by systematic searching multiple electronic databases including SciFinder, ISI Web of Science, PubMed, Google Scholar and CNKI. Information was also collected from journals, local magazines, books, monographs.

RESULTS

To date, more than 100 compounds have been isolated from this genus, include phenylethanoid glycosides, carbohydrates, lignans, iridoids, etc. The crude extracts and isolated compounds have exhibited a wide range of in vitro and in vivo pharmacologic effects, such as neuroprotective, immunomodulatory, anti-inflammatory, hepatoprotection, anti-oxidative, anti-bacterial, and anti-tumor effects. The phenylethanoid glycosides, echinacoside and acteoside have attracted the most attention for their significantly neuropharmacology effects. Pharmacokinetic studies of echinacoside and acteoside also have also been summarized.

CONCLUSION

Phenylethanoid glycosides have demonstrated wide pharmacological actions and have great clinical value if challenges such as poor bioavailability, fast and extensive metabolism are addressed. Apart from phenylethanoid glycosides, other constituents of Cistanches Herba, their pharmacological activities and underlying mechanisms are also need to be studied further.

Herba Cistanches: Anti-aging

The Cistanche species ("Rou Cong Rong" in Chinese) is an endangered wild species growing in arid or semi-arid areas. The dried fleshy stem of Cistanches has been used as a tonic in China for many years. Modern pharmacological studies have since demonstrated that Herba Cistanches possesses broad medicinal functions, especially for use in anti-senescence, anti-oxidation, neuroprotection, anti-inflammation, hepatoprotection, immunomodulation, anti-neoplastic, anti-osteoporosis and the promotion of bone formation. This review summarizes the up-to-date and comprehensive information on Herba Cistanches covering the aspects of the botany, traditional uses, phytochemistry and pharmacology, to lay ground for fully elucidating the potential mechanisms of Herba Cistanches' anti-aging effect and promote its clinical application as an anti-aging herbal medicine.

Genes of susceptibility to early neurodegenerative changes in the rat retina and brain: analysis by means of congenic strains

BACKGROUND

There has been considerable interest in discovery of the genetic architecture of complex traits, particularly age-related neurodegenerative disorders. To predict disease risk and to understand its genetic basis in humans, it is necessary to study animal models. Our previous research on the accelerated-senescence OXYS strain has revealed two quantitative trait loci (QTLs) on rat chromosome 1 that are associated with early cataract and/or retinopathy as well as with behavioral abnormalities. Each locus was partially mapped within the introgressed segments in a certain congenic strain: WAG/OXYS-1.1 or WAG/OXYS-1.2. Retinal transcriptome profiling of 20-day-old congenic and OXYS rats by high-throughput RNA sequencing uncovered relevant candidate genes and pathways. Nonetheless, the question remained open whether the same genetic components simultaneously have effects on various manifestations of the accelerated-senescence phenotype in OXYS rats. The present study was designed to analyze the genes of susceptibility to early neurodegenerative processes taking place in the OXYS rat retina and brain and to assess their potential functional clustering. The study was based on the findings from recent publications (including mapping of quantitative trait loci) and on comparative phenotyping of congenic rat strains.

RESULTS

The backcrossing of Wistar Albino Glaxo (WAG) and OXYS strains to generate the congenics resulted in two congenic strains with high susceptibility to cataract and retinopathy but with no obvious signs of Alzheimer's disease-like brain pathology that are specific for OXYS rats. Thus, the genes of susceptibility to brain neurodegeneration were not introgressed into the congenic strains or there is a strong effect of the genetic background on the disease phenotype. Moreover, the progression of retinopathy with age was relatively less severe in the WAG background compared to the OXYS background. A comparative analysis of previously defined QTLs and congenic segments led to identification of candidate genes with a suspected effect on brain neurodegeneration including the genes showing differential expression in the congenic strains.

CONCLUSION

Overall, our findings suggest that the cause of the cataract and the cause of retinopathy phenotypes in OXYS rats may be genetically linked to each other within the introgressed segments in the WAG/OXYS-1.1 and/or WAG/OXYS-1.2 congenic strains.

Amyloid accumulation is a late event in sporadic Alzheimer's disease-like pathology in nontransgenic rats

The amyloid cascade hypothesis posits that deposition of the amyloid β (Aβ) peptide in the brain is a key event in the initiation of Alzheimer's disease (AD). Nonetheless, it now seems increasingly unlikely that amyloid toxicity is the cause of sporadic AD, which leads to cognitive decline. Here, using accelerated-senescence nontransgenic OXYS rats, we confirmed that aggregation of Aβ is a later event in AD-like pathology. We showed that an age-dependent increase in the levels of Aβ_1–42 and extracellular Aβ deposits in the brain of OXYS rats occur later than do synaptic losses, neuronal cell death, mitochondrial structural abnormalities, and hyperphosphorylation of the tau protein. We identified the variants of the genes that are strongly associated with the risk of either late-onset or early-onset AD, including App, Apoe4, Bace1, Psen1, Psen2, and Picalm. We found that in OXYS rats nonsynonymous SNPs were located only in the genes Casp3 and Sorl1. Thus, we present proof that OXYS rats may be a model of sporadic AD. It is possible that multiple age-associated pathological processes may precede the toxic amyloid accumulation, which in turn triggers the final stage of the sporadic form of AD and becomes a hallmark event of the disease.

Melatonin attenuates impairments of structural hippocampal neuroplasticity in OXYS rats during active progression of Alzheimer's disease-like pathology

Translational research on Alzheimer's disease (AD) has often focused on reducing the high cerebral levels of amyloid-β (Aβ) as a key characteristic of AD pathogenesis. There is, however, a growing body of evidence that synaptic dysfunction may be crucial for the development of the most common (sporadic) form of AD. The applicability of melatonin (mainly produced by the pineal gland) to the treatment of AD is actively evaluated, but usually, such studies are based on animal models of early-onset AD, which is responsible for only ~5% of AD cases. We have shown previously that in OXYS rats (an established model of sporadic AD), accumulation of toxic forms of Aβ in the brain occurs later than does the development of signs of neurodegenerative changes and synaptic failure. In this regard, recently, we uncovered beneficial neuroprotective effects of melatonin (prophylactic dietary supplementation) in OXYS rats. Our aim here was to evaluate, starting at the age of active progression of AD-like pathology in OXYS rats, the effects of long-term oral administration of melatonin on the structure of synapses and on neuronal and glial cells of the hippocampus. Melatonin significantly increased hippocampal synaptic density and the number of excitatory synapses, decreased the number of inhibitory synapses, and upregulated pre- and postsynaptic proteins (synapsin I and PSD-95, respectively). Furthermore, melatonin improved the ultrastructure of neuronal and glial cells and reduced glial density. Based on our past and present results, the repair of neuroplasticity by melatonin is a promising strategy against AD.

RNA-Seq Based De Novo Transcriptome Assembly and Gene Discovery of Cistanche deserticola Fleshy Stem

Backgrounds

Cistanche deserticola is a completely non-photosynthetic parasitic plant with great medicinal value and mainly distributed in desert of Northwest China. Its dried fleshy stem is a crucial tonic in traditional Chinese medicine with roles of mainly improving male sexual function and strengthening immunity, but few mechanistic studies have been conducted partly due to the lack of genomic and transcriptomic resources.

Results

In this study, we performed deep transcriptome sequencing in fleshy stem of C. deserticola, and about 80 million reads were generated using Illumina pair-end sequencing on HiSeq2000 platform. Using trinity assembler, we obtained 95,787 transcript sequences with transcript lengths ranging from 200bp to 15,698bp, having an average length of 950 bases and the N50 length of 1,519 bases. 63,957 transcripts were identified actively expressed with FPKM ≥ 0.5, in which 30,098 transcripts were annotated with gene descriptions or gene ontology terms by sequence similarity analyses against several public databases (Uniprot, NR and Nt at NCBI, and KEGG). Furthermore, we identified key enzyme genes involved in biosynthesis of lignin and phenylethanoid glycosides (PhGs) which are known to be the primary active ingredients. Four phenylalanine ammonia-lyase (PAL) genes, the first key enzyme in lignin and PhG biosynthesis, were identified based on sequences comparison and phylogenetic analysis. Two biosynthesis pathways of PhGs were also proposed for the first time.

Conclusions

In all, we completed a global analysis of the C. deserticola fleshy stem transcriptome using RNA-seq technology. A collection of enzyme genes related to biosynthesis of lignin and phenylethanoid glysides were identified from the assembled and annotated transcripts, and the gene family of PAL was also predicted. The sequence data from this study will provide a valuable resource for conducting future phenylethanoid glysides biosynthesis researches and functional genomic studies in this important medicinal plant.

Application of quantitative trait locus mapping and transcriptomics to studies of the senescence-accelerated phenotype in rats

Background

Etiology of complex disorders, such as cataract and neurodegenerative diseases including age-related macular degeneration (AMD), remains poorly understood due to the paucity of animal models, fully replicating the human disease. Previously, two quantitative trait loci (QTLs) associated with early cataract, AMD-like retinopathy, and some behavioral aberrations in senescence-accelerated OXYS rats were uncovered on chromosome 1 in a cross between OXYS and WAG rats. To confirm the findings, we generated interval-specific congenic strains, WAG/OXYS-1.1 and WAG/OXYS-1.2, carrying OXYS-derived loci of chromosome 1 in the WAG strain. Both congenic strains displayed early cataract and retinopathy but differed clinically from OXYS rats. Here we applied a high-throughput RNA sequencing (RNA-Seq) strategy to facilitate nomination of the candidate genes and functional pathways that may be responsible for these differences and can contribute to the development of the senescence-accelerated phenotype of OXYS rats.

Results

First, the size and map position of QTL-derived congenic segments were determined by comparative analysis of coding single-nucleotide polymorphisms (SNPs), which were identified for OXYS, WAG, and congenic retinal RNAs after sequencing. The transferred locus was not what we expected in WAG/OXYS-1.1 rats. In rat retina, 15442 genes were expressed. Coherent sets of differentially expressed genes were identified when we compared RNA-Seq retinal profiles of 20-day-old WAG/OXYS-1.1, WAG/OXYS-1.2, and OXYS rats. The genes most different in the average expression level between the congenic strains included those generally associated with the Wnt, integrin, and TGF-β signaling pathways, widely involved in neurodegenerative processes. Several candidate genes (including Arhgap33, Cebpg, Gtf3c1, Snurf, Tnfaip3, Yme1l1, Cbs, Car9 and Fn1) were found to be either polymorphic in the congenic loci or differentially expressed between the strains. These genes may contribute to the development of cataract and retinopathy.

Conclusions

This study is the first RNA-Seq analysis of the rat retinal transcriptome generated with 40 mln sequencing read depth. The integration of QTL and transcriptomic analyses in our study forms the basis of future research into the relationship between the candidate genes within the congenic regions and specific changes in the retinal transcriptome as possible causal mechanisms that underlie age-associated disorders.

Beneficial effects of melatonin in a rat model of sporadic Alzheimer's disease

Melatonin synthesis is disordered in patients with Alzheimer's disease (AD). To determine the role of melatonin in the pathogenesis of AD, suitable animal models are needed. The OXYS rats are an experimental model of accelerated senescence that has also been proposed as a spontaneous rat model of AD-like pathology. In the present study, we demonstrate that disturbances in melatonin secretion occur in OXYS rats at 4 months of age. These disturbances occur simultaneously with manifestation of behavioral abnormalities against the background of neurodegeneration and alterations in hormonal status but before the signs of amyloid-β accumulation. We examined whether oral administration of melatonin could normalize the melatonin secretion and have beneficial effects on OXYS rats before progression to AD-like pathology. The results showed that melatonin treatment restored melatonin secretion in the pineal gland of OXYS rats as well as the serum levels of growth hormone and IGF-1, the level of BDNF in the hippocampus and the healthy state of hippocampal neurons. Additionally, melatonin treatment of OXYS rats prevented an increase in anxiety and the decline of locomotor activity, of exploratory activity, and of reference memory. Thus, melatonin may be involved in AD progression, whereas oral administration of melatonin could be a prophylactic strategy to prevent or slow down the progression of some features of AD pathology.

Ameliorative effects of SkQ1 eye drops on cataractogenesis in senescence-accelerated OXYS rats

BACKGROUND

Antioxidant supplements have been suggested as a strategy to decrease the risk of age-related cataract, but there is no evidence that antioxidants can reduce the signs of the disease. Recently, we showed that the mitochondrial antioxidant SkQ1 can partially reverse cataract signs in senescence-accelerated OXYS rats. The aim of the present study was the histomorphological examination of the influence of SkQ1 eye drops on the cataract development in OXYS rats.

METHODS

OXYS rats received SkQ1 eye drops (250 nM) from 9 to 12 months of age. Ophthalmoscopic examination was carried out before and after treatment. Light and electron microscopy were used for histomorphological examination. Expression of the Cryaa and Cryab genes was determined using real-time PCR. αB-crystallin expression was detected using Western blotting.

RESULTS

SkQ1 completely prevented the cataract development in OXYS rats, and in some of the animals diminished the signs of the disease. Light and electron microscopy showed that SkQ1 attenuated the (typical for cataract) alterations in the lens capsule and epithelial cells, ameliorated disturbances of the hexagonal packing geometry of lens fibers, and improved ultrastructure of the epithelial cells. The levels of mRNA of α-crystallins genes which encode small heat shock proteins αA- and αB-crystallin that play a central role in maintaining lens transparency were significantly lower in the OXYS rats' lenses than in Wistar rats (control). SkQ1 normalized the level of mRNA of Cryaa, and significantly increased the level of Cryab mRNA as well as αB-crystallin protein in the lens of OXYS rats to the level of the control Wistar rats.

CONCLUSION

SkQ1 eye drops hold promise as a treatment of cataract.

Senescence-accelerated OXYS rats: a model of age-related cognitive decline with relevance to abnormalities in Alzheimer disease

Senescence-accelerated OXYS rats are an experimental model of accelerated aging that was established from Wistar stock via selection for susceptibility to cataractogenic effects of a galactose-rich diet and via subsequent inbreeding of highly susceptible rats. Currently, we have the 102nd generation of OXYS rats with spontaneously developing cataract and accelerated senescence syndrome, which means early development of a phenotype similar to human geriatric disorders, including accelerated brain aging. In recent years, our group found strong evidence that OXYS rats are a promising model for studies of the mechanisms of brain aging and neurodegenerative processes similar to those seen in Alzheimer disease (AD). The manifestation of behavioral alterations and learning and memory deficits develop since the fourth week of age, i.e., simultaneously with first signs of neurodegeneration detectable on magnetic resonance imaging and under a light microscope. In addition, impaired long-term potentiation has been demonstrated in OXYS rats by the age of 3 months. With age, neurodegenerative changes in the brain of OXYS rats become amplified. We have shown that this deterioration happens against the background of overproduction of amyloid precursor protein (AβPP), accumulation of β-amyloid (Aβ), and hyperphosphorylation of the tau protein in the hippocampus and cortex. The development of AMD-like retinopathy in OXYS rats is also accompanied by increased accumulation of Aβ in the retina. These published data suggest that the OXYS strain may serve as a spontaneous rat model of AD-like pathology and could help to decipher the pathogenesis of AD.

Comparison of behavioral and biochemical deficits in rats with hereditary defined or D-galactose-induced accelerated senescence: evaluating the protective effects of diosgenin

One of the important factors in aging is oxidative stress and aging-related disturbances are believed be ameliorated by antioxidants. Diosgenin is a bio-active ingredient of dioscorea that is widely used in Chinese medicine, shows anti-oxidant activity and improves some aging-related deficits in senescent and menopausal animals. We compared alterations in behavior, biochemical parameters (plasma levels of the uric acid, creatinine, calcium, phosphate, total cholesterol, low-density lipoprotein cholesterol and triglycerides, and the plasma activity of aminotransferases AST and ALT), and sperm motility in two models of accelerated senescence (d-galactose-induced (150 mg/kg/day, i.p., 57 days) aging in Wistar rats vs. genetically defined in OXYS rats) and examined the protective effects of diosgenin (10 or 50mg/kg/day, p.o., 57 days). Both models had augmented levels of ALT activity indicating hepatopathology. Compared to d-galactose-treated animals, OXYS rats demonstrated profound biochemical alterations (hypocalcemia, hypophosphatemia, and hypocholesterolemia) and behavioral deficits (impaired object recognition, decreased sexual motivation and locomotor activity, retarded learning) that confirmed the difference in the mechanisms of accelerated senescence in these models. We first showed diminished sperm motility in males of both models of accelerated senescence studied. Chronic diosgenin treatment failed to improve biochemical and behavioral disturbances and had some undesirable side effects on body weight and working memory in OXYS rats. However, diosgenin restored moderately decreased sperm motility in d-galactose-treated Wistar males and might be recommended for treatment of mild age-related reproductive dysfunctions.

Rapamycin suppresses brain aging in senescence-accelerated OXYS rats

Cellular and organismal aging are driven in part by the MTOR (mechanistic target of rapamycin) pathway and rapamycin extends life span in C elegans, Drosophila and mice. Herein, we investigated effects of rapamycin on brain aging in OXYS rats. Previously we found, in OXYS rats, an early development of age-associated pathological phenotypes similar to several geriatric disorders in humans, including cerebral dysfunctions. Behavioral alterations as well as learning and memory deficits develop by 3 months. Here we show that rapamycin treatment (0.1 or 0.5 mg/kg as a food mixture daily from the age of 1.5 to 3.5 months) decreased anxiety and improved locomotor and exploratory behavior in OXYS rats. In untreated OXYS rats, MRI revealed an increase of the area of hippocampus, substantial hydrocephalus and 2-fold increased area of the lateral ventricles. Rapamycin treatment prevented these abnormalities, erasing the difference between OXYS and Wistar rats (used as control). All untreated OXYS rats showed signs of neurodegeneration, manifested by loci of demyelination. Rapamycin decreased the percentage of animals with demyelination and the number of loci. Levels of Tau and phospho-Tau (T181) were increased in OXYS rats (compared with Wistar). Rapamycin significantly decreased Tau and inhibited its phosphorylation in the hippocampus of OXYS and Wistar rats. Importantly, rapamycin treatment caused a compensatory increase in levels of S6 and correspondingly levels of phospo-S6 in the frontal cortex, indicating that some downstream events were compensatory preserved, explaining the lack of toxicity. We conclude that rapamycin in low chronic doses can suppress brain aging.

The mitochondria-targeted antioxidant SkQ1 but not N-acetylcysteine reverses aging-related biomarkers in rats

Although antioxidants have been repeatedly tested in animal models and clinical studies, there is no evidence that antioxidants reduce already developed age-related decline. Recently we demonstrated that mitochondria-targeted antioxidant 10-(6'-plastoquinonyl) decyltriphenylphosphonium (SkQ1) delayed some manifestations of aging. Here we compared effects of SkQ1 and N-acetyl-L-cysteine (NAC) on age-dependent decline in blood levels of leukocytes, growth hormone (GH), insulin-like growth factor-1 (IGF-1), testosterone, dehydroepiandrosterone (DHEA) in Wistar and senescence-accelerated OXYS rats. When started late in life, supplementation with SkQ1 not only prevented age-related decline but also significantly reversed it. With NAC, all the observed effects were of the lower magnitude compared with SkQ1 (in spite of that dose of NAC was 16000 times higher). We suggest that supplementation with low doses of SkQ1 is a promising intervention to achieve a healthy ageing.

Antioxidants and cataract

The major causes for cataract formation are free radicals, and these free radicals are neutralized by the presence of endogenous antioxidants in the eye. Using xenobiotics, it has been confirmed that free radicals mediate the formation of cataract. Two cataract model-selenite model and the diabetic cataract model-have been developed to study the pathophysiology of cataract formation due to free radicals and the role of antioxidants during the process of cataractogenesis. This review focuses on natural compounds with antioxidant properties that could actually be applied as an interventional strategy on a large scale and are also relatively inexpensive. A brief overview of plants with antioxidant properties that in addition possess potential anti-cataract properties has been discussed. In addition to plants, three natural compounds (curcumin, vitamin C and vitamin E), on which a lot of data exist showing anti-cataract and antioxidant activities, have also been discussed. These antioxidants can be supplemented in the diet for a better defence against free radicals. Studies on vitamin C and vitamin E have proved that they are capable of preventing lipid peroxidation, thereby preventing the generation of free radicals, but their efficacy as anti-cataract agent is questionable. Unlike vitamins C and E, curcumin is well established as an anti-cataract agent, but the issue of curcumin bioavailability is yet to be addressed. Nanotechnology proves to be a promising area in increasing the curcumin bioavailability, but still a lot more research needs to be done before the use of curcumin as an effective anti-cataract agent for humans.

The therapeutic effect of mitochondria-targeted antioxidant SkQ1 and Cistanche deserticola is associated with increased levels of tryptophan and kynurenine in the rat lens

Supplementation of senescence-accelerated OXYS rats with the mitochondria-targeted antioxidant SkQ1 and with the powder from Cistanche deserticola results in the deceleration of the cataract development and even in the improvement of lens transparency. The therapeutic effect of these preparations correlates with a significant elevation of tryptophan and kynurenine levels in the lens. This finding is attributed to a deceleration of the tryptophan and kynurenine oxidation due to antioxidant-assisted reduction of oxidative stress in the lens.

Prevention of age-related macular degeneration-like retinopathy by rapamycin in rats

Age-related macular degeneration, a neurodegenerative and vascular retinal disease, is the most common cause of blindness in the Western countries. Evidence accumulates that target of rapamycin is involved in aging and age-related diseases, including neurodegeneration. The target of rapamycin inhibitor, rapamycin, suppresses the senescent cell phenotype and extends life span in diverse species, including mice. Rapamycin decreases senescence-associated phenotypes in retinal pigment epithelial cells in culture. Herein, we investigated the effect of rapamycin on spontaneous retinopathy in senescence-accelerated OXYS rats, an animal model of age-related macular degeneration. Rats were treated with either 0.1 or 0.5 mg/kg rapamycin, which was given orally as a food mixture. In a dose-dependent manner, rapamycin decreased the incidence and severity of retinopathy. Rapamycin improved some (but not all) histological abnormalities associated with retinopathy. Thus, in retinal pigment epithelial cell layers, rapamycin decreased nuclei heterogeneity and normalized intervals between nuclei. In photoreceptor cells, associated neurons, and radial glial cells, rapamycin prevented nuclear and cellular pyknosis. More important, rapamycin prevented destruction of ganglionar neurons in the retina. Rapamycin did not exert any adverse effects on the retina in control disease-free Wistar rats. Taken together, our data suggest the therapeutic potential of rapamycin for treatment and prevention of retinopathy.

Quantitative trait loci on chromosome 1 for cataract and AMD-like retinopathy in senescence-accelerated OXYS rats

Age-related macular degeneration (AMD) and cataract are common age-related diseases in humans. Previously we showed that senescence-accelerated OXYS rats develop retinopathy and cataract, which are comparable to human AMD and senile cataract. Here we focused on the identification of quantitative trait loci (QTLs), which affect early-onset cataract and retinopathy in OXYS rats, using F2 hybrids bred by a reciprocal cross (OXYS×WAG and WAG×OXYS). Chromosome 1 showed significant associations between retinopathy and loci in the regions of markers D1Rat30 and D1Rat219 (QTL1) as well as D1Rat219 and D1Rat81 (QTL2); and between early cataract development with the locus in the region of the markers D1Rat219 and D1Rat81 (QTL2). To determine the effects of these QTLs, we generated two congenic strains by transferring chromosome 1 regions from OXYS into WAG background. Both congenic strains (named WAG/OXYS-1.1 and WAG/OXYS-1.2, respectively) display early cataract and retinopathy development. Thus, we confirmed that genes located in the analyzed regions of chromosome 1 are associated with the development of these diseases in OXYS rats.