Royal jelly-induced neurite outgrowth from rat pheochromocytoma PC12 cells requires integrin signal independent of activation of extracellular signal-regulated kinases

Royal jelly a promising therapeutic intervention and functional food supplement: A systematic review

Royal jelly (RJ), a secretion produced by honeybees, has garnered significant interest for its potential as a therapeutic intervention and functional food supplement. This systematic review aims to synthesize current research on the health benefits, bioactive components, and mechanisms of action of RJ. Comprehensive literature searches were conducted across multiple databases, including PubMed, Scopus, and Web of Science, focusing on studies published from 2000 to 2024 (April). Findings indicate that RJ exhibits a wide range of pharmacological activities, including anti-inflammatory, antioxidant, antimicrobial, and anti-aging effects. Beneficial biological properties of RJ might be due to the presence of flavonoids proteins, peptides, fatty acids. Both preclinical and clinical studies have reported that RJ improves the immune function such as wound healing, and also decreases the severity of chronic diseases including diabetes and cardiovascular disorders. The molecular mechanisms underlying these effects involve modulation of signalling pathways such as NF-κB, MAPK, and AMPK. Despite promising results, the review identifies several gaps in the current knowledge, including the need for standardized dosing regimens and long-term safety assessments. Furthermore, variations in RJ composition due to geographic and botanical factors necessitate more rigorous quality control measures. This review underscores the potential of RJ as a multifunctional therapeutic agent and highlights the necessity for further well designed studies to fully elucidate its health benefits and optimize its use as a functional food supplement.

Comparative neuroprotective effects of royal jelly and its unique compound 10-hydroxy-2-decenoic acid on ischemia-induced inflammatory, apoptotic, epigenetic and genotoxic changes in a rat model of ischemic stroke

OBJECTIVES

This study aimed to compare the efficacy of royal jelly (RJ) and its major fatty acid 10-hydroxy-2-decenoic acid (10-HDA) on ischemic stroke-related pathologies using histological and molecular approaches.

METHODS

Male rats were subjected to middle cerebral artery occlusion (MCAo) to induce ischemic stroke and were supplemented daily with either vehicle (control group), RJ or 10-HDA for 7 days starting on the day of surgery. On the eighth day, rats were sacrificed and brain tissue and blood samples were obtained to analyze brain infarct volume, DNA damage as well as apoptotic, inflammatory and epigenetic parameters.

RESULTS

Both RJ and 10-HDA supplementation significantly reduced brain infarction and decreased weight loss when compared to control animals. These effects were associated with reduced levels of active caspase-3 and PARP-1 and increased levels of acetyl-histone H3 and H4. Although both RJ and 10-HDA treatments significantly increased acetyl-histone H3 levels, the effect of RJ was more potent than that of 10-HDA. RJ and 10-HDA supplementation also alleviated DNA damage by significantly reducing tail length, tail intensity and tail moment in brain tissue and peripheral lymphocytes, except for the RJ treatment which tended to reduce tail moment in lymphocytes without statistical significance.

CONCLUSIONS

Our findings suggest that neuroprotective effects of RJ in experimental stroke can mostly be attributed to 10-HDA.

The functional mechanisms of synchronizing royal jelly consumption and physical activity on rat with multiple sclerosis-like behaviors hallmarks based on bioinformatics analysis, and experimental survey

Background

Natural nutrition and physical training have been defined as non-pharmacochemical complementary and alternative medicines to prevent and treat various pathogenesis. Royal jelly possesses various pharmacological properties and is an effective therapeutic supplement for halting neurodegeneration. Multiple sclerosis is a prevalent neurodegenerative disorder that manifests as a progressive neurological condition. Inflammation, hypoxia, and oxidative stress have been identified as significant hallmarks of multiple sclerosis pathology.

Results

In the present study, based on artificial intelligence and bioinformatics algorithms, we marked hub genes, molecular signaling pathways, and molecular regulators such as non-coding RNAs involved in multiple sclerosis. Also, microRNAs as regulators can affect gene expression in many processes. Numerous pathomechanisms, including immunodeficiency, hypoxia, oxidative stress, neuroinflammation, and mitochondrial dysfunction, can play a significant role in the MSc pathogenesis that results in demyelination. Furthermore, we computed the binding affinity of bioactive compounds presented in Royal Jelly on macromolecules surfaces. Also, we predicted the alignment score of bioactive compounds over the pharmacophore model of candidate protein as a novel therapeutic approach. Based on the q-RT-PCR analysis, the expression of the Dnajb1/Dnajb1/Foxp1/Tnfsf14 and Hspa4 networks as well as miR-34a-5p and miR155-3p were regulated by the interaction of exercise training and 100 mg/kg Royal Jelly (ET-100RJ). Interestingly, characteristics, motor function, a proinflammatory cytokine, and demyelination were ameliorated by ET-100RJ.

Discussion

Here, we indicated that interaction between exercise training and 100 mg/kg Royal jelly had a more effect on regulating the microRNA profiles and hub genes in rats with Multiple sclerosis.

Trans-10-Hydroxy-2-Decenoic Acid Alleviates Dextran Sulfate Sodium-Induced Colitis in Mice via Regulating the Inflammasome-Mediated Pyroptotic Pathway and Enhancing Colonic Barrier Function

SCOPE

The objective of this study is to explore the effects of 10-hydroxy-2-decenoic acid (10-HDA), the major fatty acid in royal jelly, on dextran sodium sulfate (DSS)-induced mice ulcerative colitis (UC) and its potential mechanism of action.

METHODS AND RESULTS

Forty male C57BL/6 mice are randomly divided into five experimental groups: control, DSS, DSS + 25 (or 100)mg kg^-1  d^-1 10-HDA, and DSS + 200 mg kg^-1  d^-1 mesalazine (ME). UC is induced in mice using 2.5% DSS in drinking water for 7 days. During the induction, these UC mice are orally administrated 10-HDA or ME per day. Meanwhile, lipopolysaccharide (LPS)/adenosine-triphosphate (ATP)-stimulated THP1 cells are used as a model to test the effects of 10-HDA. 10-HDA reduces DSS-induced pathological damage, reactive oxygen species (ROS) accumulation, neutrophil infiltration, and cytokine production in colonic tissue. Compared with the DSS group, the expressions of thioredoxin interacting protein (TXNIP), NOD-like receptor family pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC), cysteinyl aspartate specific proteinase-1 (Caspase-1), gasdermin-D (GSDMD), N-terminal domain of gasdermin-D (N-GSDMD), interleukin-1β (IL-1β), and interleukin-18 (IL-18) in the colon are decreased after administration of 10-HDA. 10-HDA also elevates the barrier integrity and the expressions of zonula occludens-1 (ZO-1) and Occludin in colonic epithelium exposed to DSS. In THP1 cells, the inflammasome-mediated pyroptosis induced by LPS/ATP is inhibited by 10-HDA pretreatment.

CONCLUSION

10-HDA alleviates DSS-induced colitis by regulating the NLRP3 inflammasome-mediated pyroptotic pathway and enhancing colonic barrier function.

Hydrolase-Treated Royal Jelly Attenuates H2O2- and Glutamate-Induced SH-SY5Y Cell Damage and Promotes Cognitive Enhancement in a Rat Model of Vascular Dementia

Vascular dementia (VaD) is the second most common type of dementia following Alzheimer's disease, but the therapeutic efficacy is still not effective. This makes the searching for novel neuroprotective agents important. Therefore, we hypothesized that royal jelly, a well-known traditional medicine, could attenuate memory impairment and brain damage in vascular dementia. This study determined the effects of royal jelly hydrolysate (RJH) and possible mechanism of cell damage and cognitive-enhancing effect in animal study. An in vitro study assessed the effects of RJH on acetylcholinesterase inhibitor, cell viability, and cell damage in SH-SY5Y neuroblastoma cells. Then, an in vivo study examined vascular dementia by the occlusion of the right middle cerebral artery (Rt.MCAO); adult male Wistar rats had been orally given RJH at doses ranging from 10, 50, to 100 mg/kg for 14 days before and 14 days after the occlusion of Rt.MCAO to mimic the VaD condition. Rats' spatial memory was evaluated using Morris water maze and radial arm maze every 7 days after Rt.MCAO throughout a 14-day experimental period, and then, they were sacrificed and the acetylcholinesterase (AChE) activity in the hippocampus was determined. The results showed that RJH has no cytotoxic effect with the final concentration up to 500 μg protein/ml and reduces cell death from the H₂O₂- and glutamate-induced cell damage in in vitro neuroblastoma cells. Importantly, RJH significantly improved memory performance in Morris water maze test and radial arm maze and decreased the level of acetyl cholinesterase activity. In conclusion, RJH is the potential neuroprotective agent and cognitive enhancer for VaD.

Combined effects of royal jelly and environmental enrichment against stress-induced cognitive and behavioral alterations in male rats: behavioral and molecular studies

BACKGROUND

Exposure to chronic stress has detrimental effects on cognitive and emotional processing. Also, the neuroprotective influences of environmental enrichment (EE) and royal jelly (RJ) have been indicated in previous studies.

AIMS

To our knowledge, to date, there are no studies about the synergistic effects of EE and RJ on cognitive changes induced by stress. Therefore, this study aimed to investigate the protective effects of RJ, and EE on anxiety-like behaviors, cognitive functions, and expression of hippocampal and also prefrontal cortex (PFC) brain-derived neurotrophic factor (BDNF) levels in stressed rats.

METHODS

By using restraint and cold temperature, rats were exposed to stressful situations and then subjected to treatment with RJ or/ and EE for 14 days. Stress induction was done 14 days before treatments by placing the rats in the restrainer under 4°C. Following the interventions, anxiety-like behaviors, novel object recognition memory (NORM), inhibitive avoidance performance, hippocampal, and PFC BDNF expression were examined. The plasma corticosterone level of all groups was also evaluated.

RESULTS

Results showed increased plasma corticosterone levels, stress-induced deficits in the NORM and IA tests, and increased anxiety-like behaviors. EE and RJ improved these deficits with a decline in serum corticosterone and also increased BDNF levels in the hippocampus and PFC in stressed ones.

CONCLUSION

The EE and the RJ prevented the detrimental effects of stress on anxiety-like behaviors and memory processes. These treatments can protect susceptible brain areas against chronic stress via improvement in behavioral and cognitive impairments through mediating BDNF expression.

Apitherapy for Parkinson's Disease: A Focus on the Effects of Propolis and Royal Jelly

The vast increase of world's aging populations is associated with increased risk of age-related neurodegenerative diseases such as Parkinson's disease (PD). PD is a widespread disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra, which encompasses a wide range of debilitating motor, emotional, cognitive, and physical symptoms. PD threatens the quality of life of millions of patients and their families. Additionally, public welfare and healthcare systems are burdened with its high cost of care. Available treatments provide only a symptomatic relief and produce a trail of noxious side effects, which increase noncompliance. Hence, researchers have recently focused on the use of nutraceuticals as safe adjunctive treatments of PD to limit its progress and associated damages in affected groups. Propolis is a common product of the beehive, which possesses a large number of therapeutic properties. Royal jelly (RJ) is a bee product that is fed to bee queens during their entire life, and it contributes to their high physical fitness, fertility, and long lifespan. Evidence suggests that propolis and RJ can promote health by preventing the occurrence of age-related debilitating diseases. Therefore, they have been used to treat various serious disorders such as diabetes mellitus, cardiovascular diseases, and cancer. Some evolving studies used these bee products to treat PD in animal models. However, a clear understanding of the collective effect of propolis and RJ as well as their mechanism of action in PD is lacking. This review evaluates the available literature for the effects of propolis and RJ on PD. Whenever possible, it elaborates on the underlying mechanisms through which they function in this disorder and offers insights for fruitful use of bee products in future clinical trials.

Royal Jelly as an Intelligent Anti-Aging Agent-A Focus on Cognitive Aging and Alzheimer's Disease: A Review

The astronomical increase of the world's aged population is associated with the increased prevalence of neurodegenerative diseases, heightened disability, and extremely high costs of care. Alzheimer's Disease (AD) is a widespread, age-related, multifactorial neurodegenerative disease that has enormous social and financial drawbacks worldwide. The unsatisfactory outcomes of available AD pharmacotherapy necessitate the search for alternative natural resources that can target various the underlying mechanisms of AD pathology and reduce disease occurrence and/or progression. Royal jelly (RJ) is the main food of bee queens; it contributes to their fertility, long lifespan, and memory performance. It represents a potent nutraceutical with various pharmacological properties, and has been used in a number of preclinical studies to target AD and age-related cognitive deterioration. To understand the mechanisms through which RJ affects cognitive performance both in natural aging and AD, we reviewed the literature, elaborating on the metabolic, molecular, and cellular mechanisms that mediate its anti-AD effects. Preclinical findings revealed that RJ acts as a multidomain cognitive enhancer that can restore cognitive performance in aged and AD models. It promotes brain cell survival and function by targeting multiple adversities in the neuronal microenvironment such as inflammation, oxidative stress, mitochondrial alterations, impaired proteostasis, amyloid-β toxicity, Ca excitotoxicity, and bioenergetic challenges. Human trials using RJ in AD are limited in quantity and quality. Here, the limitations of RJ-based treatment strategies are discussed, and directions for future studies examining the effect of RJ in cognitively impaired subjects are noted.

Apitherapy for Age-Related Skeletal Muscle Dysfunction (Sarcopenia): A Review on the Effects of Royal Jelly, Propolis, and Bee Pollen

The global pandemic of sarcopenia, skeletal muscle loss and weakness, which prevails in up to 50% of older adults is increasing worldwide due to the expansion of aging populations. It is now striking young and midlife adults as well because of sedentary lifestyle and increased intake of unhealthy food (e.g., western diet). The lockdown measures and economic turndown associated with the current outbreak of Coronavirus Disease 2019 (COVID-19) are likely to increase the prevalence of sarcopenia by promoting sedentarism and unhealthy patterns of eating. Sarcopenia has multiple detrimental effects including falls, hospitalization, disability, and institutionalization. Although a few pharmacological agents (e.g., bimagrumab, sarconeos, and exercise mimetics) are being explored in different stages of trials, not a single drug has been approved for sarcopenia treatment. Hence, research has focused on testing the effect of nutraceuticals, such as bee products, as safe treatments to prevent and/or treat sarcopenia. Royal jelly, propolis, and bee pollen are common bee products that are rich in highly potent antioxidants such as flavonoids, phenols, and amino acids. These products, in order, stimulate larval development into queen bees, promote defenses of the bee hive against microbial and environmental threats, and increase royal jelly production by nurse bees. Thanks to their versatile pharmacological activities (e.g., anti-aging, anti-inflammatory, anticarcinogenic, antimicrobial, etc.), these products have been used to treat multiple chronic conditions that predispose to muscle wasting such as hypertension, diabetes mellitus, cardiovascular disorder, and cancer, to name a few. They were also used in some evolving studies to treat sarcopenia in laboratory animals and, to a limited degree, in humans. However, a collective understanding of the effect and mechanism of action of these products in skeletal muscle is not well-developed. Therefore, this review examines the literature for possible effects of royal jelly, bee pollen, and propolis on skeletal muscle in aged experimental models, muscle cell cultures, and humans. Collectively, data from reviewed studies denote varying levels of positive effects of bee products on muscle mass, strength, and function. The likely underlying mechanisms include amelioration of inflammation and oxidative damages, promotion of metabolic regulation, enhancement of satellite stem cell responsiveness, improvement of muscular blood supply, inhibition of catabolic genes, and promotion of peripheral neuronal regeneration. This review offers suggestions for other mechanisms to be explored and provides guidance for future trials investigating the effects of bee products among people with sarcopenia.

The effect of royal jelly on boar sperm viability and motility during liquid storage for 96 hours

The current study was carried out to investigate the protective effects of royal jelly supplementation on sperm motility, viability and pH value during the liquid storage of boar semen at 16 °C and 4 °C, at various periods of time (0, 24, 48, 72 and 96 h). Semen samples were collected from 11 boars, diluted with a long-term extender and supplemented with different concentration of royal jelly (0%, 0.5%, 1% and 2%) at a final concentration of 50 × 106 sperm/ml. In the laboratory, the semen was assessed for sperm morphology, viability (eosin-nigrosin staining), subjective motility and objective sperm motility by sperm class analyzer. In total, 396 tests for sperm viability and motility were performed. The longer storage time and the lower incubation temperature showed lower sperm motility and viability results. The results showed that royal jelly supplementation at 1% concentrations protected the functionality of the sperm plasma membrane during the liquid storage time of 96 h at 16 °C. Sperm subjective and objective motility results in samples stored at 4 °C decreased with higher royal jelly concentrations and longer storage time, and differ significantly from the results in samples stored at 16 °C (P < 0.05). Our data showed that royal jelly supplementation at lower concentrations can improve boar semen motility and viability parameters during liquid storage at 16 °C for 96 h.

New Insights into the Biological and Pharmaceutical Properties of Royal Jelly

Royal jelly (RJ) is a yellowish-white and acidic secretion of hypopharyngeal and mandibular glands of nurse bees used to feed young worker larvae during the first three days and the entire life of queen bees. RJ is one of the most appreciated and valued natural product which has been mainly used in traditional medicines, health foods, and cosmetics for a long time in different parts of the world. It is also the most studied bee product, aimed at unravelling its bioactivities, such as antimicrobial, antioxidant, anti-aging, immunomodulatory, and general tonic action against laboratory animals, microbial organisms, farm animals, and clinical trials. It is commonly used to supplement various diseases, including cancer, diabetes, cardiovascular, and Alzheimer's disease. Here, we highlight the recent research advances on the main bioactive compounds of RJ, such as proteins, peptides, fatty acids, and phenolics, for a comprehensive understanding of the biochemistry, biological, and pharmaceutical responses to human health promotion and life benefits. This is potentially important to gain novel insight into the biological and pharmaceutical properties of RJ.

Royal Jelly and Its Components Promote Healthy Aging and Longevity: From Animal Models to Humans

Aging is a natural phenomenon that occurs in all living organisms. In humans, aging is associated with lowered overall functioning and increased mortality out of the risk for various age-related diseases. Hence, researchers are pushed to find effective natural interventions that can promote healthy aging and extend lifespan. Royal jelly (RJ) is a natural product that is fed to bee queens throughout their entire life. Thanks to RJ, bee queens enjoy an excellent reproductive function and lengthened lifespan compared with bee workers, despite the fact that they have the same genome. This review aimed to investigate the effect of RJ and/or its components on lifespan/healthspan in various species by evaluating the most relevant studies. Moreover, we briefly discussed the positive effects of RJ on health maintenance and age-related disorders in humans. Whenever possible, we explored the metabolic, molecular, and cellular mechanisms through which RJ can modulate age-related mechanisms to extend lifespan. RJ and its ingredients—proteins and their derivatives e.g., royalactin; lipids e.g., 10-hydroxydecenoic acid; and vitamins e.g., pantothenic acid—improved healthspan and extended lifespan in worker honeybees Apis mellifera, Drosophila Melanogaster flies, Gryllus bimaculatus crickets, silkworms, Caenorhabditis elegans nematodes, and mice. The longevity effect was attained via various mechanisms: downregulation of insulin-like growth factors and targeting of rapamycin, upregulation of the epidermal growth factor signaling, dietary restriction, and enhancement of antioxidative capacity. RJ and its protein and lipid ingredients have the potential to extend lifespan in various creatures and prevent senescence of human tissues in cell cultures. These findings pave the way to inventing specific RJ anti-aging drugs. However, much work is needed to understand the effect of RJ interactions with microbiome, diet, activity level, gender, and other genetic variation factors that affect healthspan and longevity.

Royal Jelly Alleviates Cognitive Deficits and β-Amyloid Accumulation in APP/PS1 Mouse Model Via Activation of the cAMP/PKA/CREB/BDNF Pathway and Inhibition of Neuronal Apoptosis

Alzheimer’s disease (AD) is characterized clinically by progressive cognitive decline and pathologically by the accumulation of amyloid-β (Aβ) in the brain. Royal jelly (RJ), a secretion of honeybee hypopharyngeal and mandibular glands, has previously been shown to have anti-aging and neuromodulatory activities. In this study, we discovered that 3 months of RJ treatment substantially ameliorated behavioral deficits of APP/PS1 mice in the Morris Water Maze (MWM) test and step-down passive avoidance test. Our data also showed that RJ significantly diminished amyloid plaque pathology in APP/PS1 mice. Furthermore, RJ alleviated c-Jun N-terminal kinase (JNK) phosphorylation-induced neuronal apoptosis by suppressing oxidative stress. Importantly, hippocampal cyclic adenosine monophosphate (cAMP), p-PKA, p-CREB and BDNF levels were significantly increased in the APP/PS1 mice after RJ treatment, indicating that the cAMP/PKA/CREB/BDNF pathway might be related to the ameliorative effect of RJ on cognitive decline. Collectively, these results provide a scientific basis for using RJ as a functional food for targeting AD pathology.

Long-Term Administration of Queen Bee Acid (QBA) to Rodents Reduces Anxiety-Like Behavior, Promotes Neuronal Health and Improves Body Composition

Background: Queen bee acid (QBA; 10-hydroxy-2-decenoic acid) is the predominant fatty acid in royal jelly (RJ) and has activity at estrogen receptors, which affect brain function and body composition. However, few, long-term studies have assessed QBA effects in brain health and body composition. Methods: Primary hippocampal neurons were treated with QBA (0–30 µM) and challenged with glutamate or hypoxia. QBA was fed to aged, male Sprague-Dawley rats (12–24 mg/kg/day) and to adult male and female Balb/C mice (30–60 mg/kg/day) for ≥3.5 months. Rats were evaluated in a behavioral test battery of brain function. Mice were measured for fat and muscle composition, as well as bone density. Results: QBA increased neuron growth and protected against glutamate challenge and hypoxia challenge. Rats receiving QBA had reduced anxiety-like behavior, increased body weight, and better maintenance of body weight with age. Mice receiving QBA exhibited increased body weight, muscle mass, and adiposity in males, and increased bone density, but decreased adiposity, in females. Conclusions: QBA is an active component of RJ that promotes the growth and protection of neurons, reduces anxiety-like phenotypes, and benefits bone, muscle and adipose tissues in a sex-dependent manner, which further implicates estrogen receptors in the effects of QBA.

Improvement of neurological disorders in postmenopausal model rats by administration of royal jelly

OBJECTIVE

Royal jelly (RJ) from honeybees (Apis mellifera) has estrogenic activity. Estrogen deficiency after menopause leads to a high risk of memory impairment and depression as well as metabolic syndrome and osteoporosis. We here investigated the effect of RJ on memory impairment and depression-like behaviors in ovariectomized (OVX) rats.

METHODS

OVX rats were administered with RJ for 82 days. Hippocampus-dependent spatial memory and depression-like behaviors were assessed by the Morris water maze test and the forced swimming test, respectively. The weights of body, brain and uterus and the contents of protein and myelin galactolipids including galactosylceramide and sulfatide were measured.

RESULTS

Memory impairment and depression-like behaviors in OVX rats were recovered to the levels of sham-operated rats by RJ administration. Increased body weight and decreased uterine weight in OVX rats were recovered to the levels of sham-operated rats by 17β-estradiol (E2) administration but not by RJ administration. In contrast, brain weight was slightly increased by RJ administration but not by E2 administration. The contents of protein and myelin galactolipids were higher in the brains of RJ-administered OVX rats than in the brains of E2-administered OVX rats.

CONCLUSION

The results suggest that RJ has a beneficial effect on neurological symptoms of a menopausal disorder.

Probing relevant molecules in modulating the neurite outgrowth of hippocampal neurons on substrates of different stiffness

Hippocampal neurons play a critical role in learning and memory; however, the effects of environmental mechanical forces on neurite extension and associated underlying mechanisms are largely unexplored, possibly due to difficulties in maintaining central nervous system neurons. Neuron adhesion, neurite length, and mechanotransduction are mainly influenced by the extracellular matrix (ECM), which is often associated with structural scaffolding. In this study, we investigated the relationship between substrate stiffness and hippocampal neurite outgrowth by controlling the ratios of polydimethylsiloxane (PDMS) base to curing agent to create substrates of varying stiffness. Immunostaining results demonstrated that hippocampal neurons have longer neurite elongation in 35:1 PDMS substrate compared those grown on 15:1 PDMS, indicating that soft substrates provide a more optimal stiffness for hippocampal neurons. Additionally, we discovered that pPKCα expression was higher in the 15:1 and 35:1 PDMS groups than in the poly-L-lysine-coated glass group. However, when we used a fibronectin (FN) coating, we found that pFAKy397 and pFAKy925 expression were higher in glass group than in the 15:1 or 35: 1 PDMS groups, but pPKCα and pERK1/2 expression were higher in the 35:1 PDMS group than in the glass group. These results support the hypothesis that environmental stiffness influences hippocampal neurite outgrowth and underlying signaling pathways.

Effect of Royal Jelly on spatial learning and memory in rat model of streptozotocin-induced sporadic Alzheimer's disease

Background:

It has been recently demonstrated that Royal jelly (RJ) has a beneficial role on neural functions. Alzheimer's disease (AD) is associated with impairments of learning and memory. Therefore, the present study was designed to examine the effect of RJ on spatial learning and memory in rats after intracerebroventricular injection of streptozotocin (icv-STZ).

Materials and Methods:

Rats were infused bilaterally with an icv injection of STZ, while sham rats received vehicle only. The rats were feed with RJ-contained food (3% w/w) (lyophilized RJ mixed with powdered regular food) or regular food for 10 days. Then spatial learning and memory was tested in the rats by Morris water maze test.

Results:

Results showed that in icv-STZ group latency and path length were increased as compared to sham group, also icv-STZ rats less remembered the target quadrant that previously the platform was located; however, these were protected significantly in STZ group that received RJ-containing food.

Conclusions:

Our findings support the potential neuroprotective role of RJ and its helpful effects in AD.

2-decenoic acid ethyl ester, a compound that elicits neurotrophin-like intracellular signals, facilitating functional recovery from cerebral infarction in mice

In our previous study, we found that trans-2-decenoic acid ethyl ester (DAEE), a derivative of a medium-chain fatty acid, elicits neurotrophin-like signals including the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) in cultured mouse cortical neurons. Here, we examined the efficacy of intraperitoneal administration of DAEE on the treatment of a mouse model of the cerebral infarction caused by unilateral permanent middle cerebral artery occlusion (PMCAO). DAEE-treatment (100 μg/kg body weight injected at 0.5, 24, 48, 72 h after PMCAO) significantly restored the mice from PMCAO-induced neurological deficits including motor paralysis when evaluated 48, 72, and 96 h after the PMCAO. Furthermore, DAEE facilitated the phosphorylation of ERK1/2 on the infarction side of the brain when analyzed by Western immunoblot analysis, and it enhanced the number of phosphorylated ERK1/2-positive cells in the border areas between the infarction and non-infarction regions of the cerebral cortex, as estimated immunohistochemically. As the infarct volume remained unchanged after DAEE-treatment, it is more likely that DAEE improved the neurological condition through enhanced neuronal functions of the remaining neurons in the damaged areas rather than by maintaining neuronal survival. These results suggest that DAEE has a neuro-protective effect on cerebral infarction.

Lifespan-extending effects of royal jelly and its related substances on the nematode Caenorhabditis elegans

Background

One of the most important challenges in the study of aging is to discover compounds with longevity-promoting activities and to unravel their underlying mechanisms. Royal jelly (RJ) has been reported to possess diverse beneficial properties. Furthermore, protease-treated RJ (pRJ) has additional pharmacological activities. Exactly how RJ and pRJ exert these effects and which of their components are responsible for these effects are largely unknown. The evolutionarily conserved mechanisms that control longevity have been indicated. The purpose of the present study was to determine whether RJ and its related substances exert a lifespan-extending function in the nematode Caenorhabditis elegans and to gain insights into the active agents in RJ and their mechanism of action.

Principal Findings

We found that both RJ and pRJ extended the lifespan of C. elegans. The lifespan-extending activity of pRJ was enhanced by Octadecyl-silica column chromatography (pRJ-Fraction 5). pRJ-Fr.5 increased the animals' lifespan in part by acting through the FOXO transcription factor DAF-16, the activation of which is known to promote longevity in C. elegans by reducing insulin/IGF-1 signaling (IIS). pRJ-Fr.5 reduced the expression of ins-9, one of the insulin-like peptide genes. Moreover, pRJ-Fr.5 and reduced IIS shared some common features in terms of their effects on gene expression, such as the up-regulation of dod-3 and the down-regulation of dod-19, dao-4 and fkb-4. 10-Hydroxy-2-decenoic acid (10-HDA), which was present at high concentrations in pRJ-Fr.5, increased lifespan independently of DAF-16 activity.

Conclusions/Significance

These results demonstrate that RJ and its related substances extend lifespan in C. elegans, suggesting that RJ may contain longevity-promoting factors. Further analysis and characterization of the lifespan-extending agents in RJ and pRJ may broaden our understanding of the gene network involved in longevity regulation in diverse species and may lead to the development of nutraceutical interventions in the aging process.

Royal jelly facilitates restoration of the cognitive ability in trimethyltin-intoxicated mice

Trimethyltin (TMT) is a toxic organotin compound that induces acute neuronal death selectively in the hippocampal dentate gyrus (DG) followed by cognition impairment; however the TMT-injured hippocampal DG itself is reported to regenerate the neuronal cell layer through rapid enhancement of neurogenesis. Neural stem/progenitor cells (NS/NPCs) are present in the adult hippocampal DG, and generate neurons that can function for the cognition ability. Therefore, we investigated whether royal jelly (RJ) stimulates the regenerating processes of the TMT-injured hippocampal DG, and found that orally administered RJ significantly increased the number of DG granule cells and simultaneously improved the cognitive impairment. Furthermore, we have already shown that RJ facilitates neurogenesis of cultured NS/NPCs. These present results, taken together with previous observations, suggest that the orally administered RJ may be a promising avenue for ameliorating neuronal function by regenerating hippocampal granule cells that function in the cognition process.

AMP N1-oxide potentiates astrogenesis by cultured neural stem/progenitor cells through STAT3 activation

We earlier identified adenosine monophosphate (AMP) N1-oxide as a unique compound of royal jelly (RJ) that induces neurite outgrowth from cultured rat pheochromocytoma PC12 cells. In the present study, the effects of AMP N1-oxide on the proliferation and/or differentiation of cultured neural stem/progenitor cells (NSCs) were examined. As for cell proliferation, low micromolar concentrations of AMP N1-oxide or its parent compound, AMP, similarly enhanced the NSC proliferation-inducing activity of basic fibroblast growth factor (FGF-2), although neither compound tested alone affected cell proliferation. Conversely, high concentrations of AMP N1-oxide (over 20 microM) markedly suppressed cell growth even in the presence of FGF-2. However, this suppression was not observed with AMP. As for cell differentiation, AMP N1-oxide, but not AMP, increased the generation of astrocytes in a dose-dependent manner when the cells were cultured in medium lacking FGF-2. The generation of neurons or oligodendrocytes was not influenced by AMP N1-oxide. Furthermore, AMP N1-oxide increased the phosphorylation of STAT3 (signal transducer and activator of transcription 3), a transcription factor that mediates the expression of astrocytespecific genes. These results suggest that AMP N1-oxide is one of the components that facilitates astrogenesis by NSCs through activation of STAT3.

Royal jelly and its unique fatty acid, 10-hydroxy-trans-2-decenoic acid, promote neurogenesis by neural stem/progenitor cells in vitro

Neural stem/progenitor cells (NSCs) proliferate vigorously as neurospheres in medium containing basic fibroblast growth factor (FGF-2), but start differentiating into neurons, astrocytes or oligodendrocytes in FGF-2-free medium. An extract of royal jelly (RJ) significantly increased the percentage in the total cell population of not only neurons immunoreactive for class III beta-tubulin (Tuj1) but also astrocytes immunoreactive for glial fibrillary acidic protein (GFAP), and oligodendrocytes immunoreactive for 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) generated from NSCs, but decreased that of nestin-positive NSCs. These results highlight a novel and outstanding property of the RJ, i.e., that it facilitates the differentiation of all types of brain cells (neurons, astrocytes, and oligodendrocytes). On the other hand, 10-hydroxy-trans-2-decenoic acid (HDEA), an unsaturated fatty acid characteristic of RJ, increased the generation of neurons and decreased that of astrocytes from NSCs. These observations suggest that RJ contains plural components that differently influence neuronal and/or glial lineages and that HDEA is one of such components of RJ that facilitates neurogenesis by NSCs.