Interkingdom Hormonal Regulations between Plants and Animals Provide New Insight into Food Safety

Food safety has become an attractive topic among consumers. Raw material production for food is also a focus of social attention. As hormones are widely used in agriculture and human disease control, consumers' concerns about the safety of hormone agents have never disappeared. The present review focuses on the interkingdom regulations of exogenous animal hormones in plants and phytohormones in animals, including physiology and stress resistance. We summarize these interactions to give the public, researchers, and policymakers some guidance and suggestions. Accumulated evidence demonstrates comprehensive hormonal regulation across plants and animals. Animal hormones, interacting with phytohormones, help regulate plant development and enhance environmental resistance. Correspondingly, phytohormones may also cause damage to the reproductive and urinary systems of animals. Notably, the disease-resistant role of phytohormones is revealed against neurodegenerative diseases, cardiovascular disease, cancer, and diabetes. These resistances derive from the control for abnormal cell cycle, energy balance, and activity of enzymes. Further exploration of these cross-kingdom mechanisms would surely be of greater benefit to human health and agriculture development.

Ameliorative effects of Dictyota dichotoma on hepatotoxicity induced by gibberellic acid in albino rats

Gibberellic acid (GA3) is a natural plant growth regulator that is crucial for plant structural and functional development. We examined the alleviating capacity of brown algae (Dictyota dichotoma) on biochemical and molecular degenerative processes caused by sub-chronic exposure to gibberellic acid resulting in hepatic cell apoptosis. Adult male albino rats were divided into five equal groups: the first group received distilled water, the second group was treated with GA3, the third group was administered D. dichotoma extract suspended in 1% carboxymethylcellulose (CMC), the fourth group was administered both GA3 and D. dichotoma simultaneously, and the fifth group received 1% CMC orally, 5 days per week for a total of 50 days. The results indicated that GA3 induced a significant increase in liver function parameters based on serum levels of alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and albumin, which indicate hepatotoxicity. A marked increase in malondialdehyde (MDA) levels and a marked decrease in reduced glutathione (GSH), glutathione-S-transferase (GST), and superoxide dismutase (SOD) were observed as a result of induction of lipid peroxidation and oxidative stress. Histopathology revealed severely degenerated hepatocytes including cytoplasmic vacuolations and many apoptotic cells with weak Bcl2 expression. Similarly, there was a significant up-regulation of gene and protein expression levels for the pro-apoptotic markers, Caspase-3 and Bax, and an increase in pro-inflammatory marker levels, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) as well as C-reactive protein (CRP). The co-administration of D. dichotoma restored the disrupted biochemical, histopathological, molecular, and inflammatory changes resulting from GA3 toxicity. Our results confirm the antioxidant, anti-inflammatory, anti-apoptotic, and hepatoprotective potential of D. dichotoma.

Transformation kinetics and mechanism of gibberellic acid with ferrihydrite: Building a novel adsorption-transformation multi-step kinetic model

Gibberellic acid (GA₃), a widely used phytohormone, is easily transformed into more toxic products. The soil and groundwater environment are an important sink for GA₃, but its transformation catalyzed by soil minerals has not been studied. In this study, the transformation kinetics and mechanism of GA₃ with ferrihydrite (Fh) were examined through kinetic batch experiments, microscopic-spectroscopic investigation and mathematical modeling. The results showed that rapid adsorption of GA₃ on Fh occurred in the first 4 h, followed by a catalytic pseudo-first-order transformation of the parent compound and products generation (4 h-30 d). Fh predominantly enhanced the transformation of GA₃ into Iso-GA₃ which was further hydrolyzed into OH-GA₃, in which adsorption was a prerequisite for transformation. The catalytic transformation likely resulted from the surface hydroxy of Fh, which not only stabilized the transformation intermediates by forming surface complexes with the carboxyl group of GA₃ and its products, but also served as a powerful nucleophile to attack the γ-lactone of GA₃ and Iso-GA₃. Based on the catalytic isomerization and hydrolysis mechanism of GA₃ with Fh, a novel adsorption-transformation multi-step kinetic conceptual model and mathematical model were developed. This model fitted the measured data well (R² > 0.97) and the fitted parameters suggested that the transformation rate constants of the transformation of GA₃ into Iso-GA₃ and the transformation of Iso-GA₃ into OH-GA₃ were facilitated with Fh by ∼26 and ∼9 times, respectively. The multi-step kinetic model has great potential in simulating GA₃ fate in soil and groundwater to assess its environmental health risk.

Insights into pH-dependent transformation of gibberellic acid in aqueous solution: Transformation pathway, mechanism and toxicity estimation

Gibberellic acid (GA₃) is widely used in agriculture and maybe transfer with groundwater flow, which is an endocrine disruptor, but few studies have focused on the transformation pathway and toxicity assessment of GA₃ and its products. Here, GA₃ and its transformation products in aqueous solution were identified and quantified by liquid chromatography mass spectrometry hybrid ion trap time-of-flight (LCMS-IT-TOF) and high-performance liquid chromatography (HPLC), respectively. The results showed that the half-life of GA₃ transformation in ultrapure water was 16.1-24.6 days at pH=2.0-8.0, with the lowest half-life occurring at pH=8.0 and highest half-life occurring at pH=3.3. Isomerized gibberellic acid (Iso-GA₃) and gibberellenic acid (GEA) were the main transformation products with a little hydroxy gibberellic acid (OH-GA₃). In North China groundwater, the mass balance of GA₃ and its products was 76.2%, including Iso-GA₃ (58%), GEA (7.9%), GA₃ (7.3%) and OH-GA₃ (3%) after reaching transformation equilibrium. Using Gaussian 09 for chemical computation, it was found that the transformation mechanism of GA₃ was dependent upon the bond energy and the stereochemical feature of its molecular structure. GA₃ always isomerized from the γ-lactone ring due to the lowest bond energy between the oxygen terminus of the γ-lactone ring and A ring. While GA₃ and its transformation products all had developmental toxicity, the predicated LC₅₀ (96 hr) and LD₅₀ of the main products of GA₃ were much lower than those of GA₃, indicating GA₃ would be transformed into higher toxicity derivatives in water environments, posing a significant health risk to humans and the environment.

Impacts of n-acetyl cysteine on gibberellic acid-induced testicular dysfunction through regulation of inflammatory cytokines, steroid and antioxidant activity

In agriculture, gibberellic acid (GA3) is commonly used with extreme dangers for public health. The current research evaluates the improving effects of n-acetyl cysteine (NAC, 150 mg/kg bw) co-administered with GA3 (55 mg/kg bw) mediated testicular injury. Twenty-four male albino rats were split into 4 groups: Negative control (CNT), NAC group, positive GA3 group and protective group, co-administered NAC plus GA3. On day 21, rats were anesthetised then euthanised by decapitation. Blood samples were collected; testicular samples were taken for semen analysis, serum chemistry, RNA extraction, histological and antioxidants markers examination. Our results revealed a significant decline p < .05 of catalase level and total antioxidant capacity. There was a substantial rise of MDA concentration in GA3-treated rats along with a considerable decrease of the antioxidant markers (SOD, GSH) and serum male reproductive hormones. In GA3-treated rats, an overexpression of the inflammatory cytokines (TNF-α, IL-1β) and anti-inflammatory cytokine IL-10 with boost mRNA expression of nuclear factor-kappa (NF_k B) were confirmed. There was downregulation of steroidogenesis genes and decrease in sperm quality and concentration with an increase in sperm abnormalities, all were reported in GA3-treated rats. NAC treatment significantly increased the antioxidant state, testicular function beside structural germ cell and seminiferous tubules histology accompanied by upsurge of steroidogenic mRNA expressions (P450scc and 3β-HSD) and downregulated the pro-inflammatory cytokines mRNA expression (TNF-α, IL-1β). These results confirm the antioxidant capability of NAC and afford robust evidence about the ameliorative effect of the NAC to attenuate the testicular injury induced by GA3 through modulation of the antioxidant defence system, steroidogenic and pro-inflammatory cytokines mRNA expression.

Continuous gibberellin A3 exposure from weaning to sexual maturity induces ovarian granulosa cell apoptosis by activating Fas-mediated death receptor signaling pathways and changing methylation patterns on caspase-3 gene promoters

Information on the effects of gibberellic acid (gibberellin A3, GA3) on ovarian follicle development is limited. In our present study, 21-day-old female Wistar rats were exposed to GA3 by gavage (25, 50, and 100 mg/kg body weight, once per day) for eight weeks to evaluate the influence of GA3 on ovarian follicle development. After treatment, significant (P < 0.05) increases (to 40.17 % and 44.5 %, respectively) in atretic follicle proportions and significant decreases (to 19.49 % and 17.86 %, respectively) in corpus luteum proportions were observed in the 50 and 100 mg/kg treatment groups compared to the control group. Significant (P < 0.05) increases (to 31.3 % and 42.0 %, respectively) in follicle apoptosis were observed in the 50 and 100 mg/kg treatment groups by transmission electron microscopy and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assays. Significantly increased expression of caspase-3, caspase-8, caspase-9 and Fas was observed by real-time PCR and Western blotting. Bisulfite sequencing PCR (BSP) revealed obviously decreased total methylation percentages of the caspase-3 promoter region in the two treatment groups. Real-time quantitative PCR also showed significantly decreased mRNA expression of DNA methyltransferase (Dnmt) 3a and Dnmt3b. Further in vitro studies showed that a DNA methylation inhibitor could enhance the GA3-induced increase in the mRNA expression of caspase-3. Overall, our present study indicates that GA3 administration from weaning until sexual maturity can affect ovarian follicle development by inducing apoptosis and suggests that signaling through the Fas-mediated apoptotic pathway may be an important underlying mechanism of this apoptosis. In addition, GA3-induced aberrant DNA methylation patterns might be partly responsible for upregulation of caspase-3 gene expression.

28-Homobrassinolide: a novel oxysterol transactivating LXR gene expression

Cholesterol is the template for steroid hormone biosynthesis. Cholesterol homeostasis is regulated by Cyt-P450 oxygenated cholesterols acting as ligands on LXR-α and LXR-β transcription factors that are now emerging as drug targets. Heterodimerization of LXRs with retinoic acid receptor is considered a prerequisite for target gene activation. Dietary plant oxysterol 28-homobrassinolide (28-HB) is a proven antihyperglycemic and a pro-steroidogenic agent in the rat. Whether 28-HB has a role in LXR gene expression was therefore investigated using oral gavage (15 days) of 28-HB (333 µg/kg b w) to normal and diabetic rat. PCR amplified LXR-α and β mRNA transcripts from treated rat liver and testis exhibited quantitative differences in their expression. Conformational differences in 28-HB docking to LXR-α and β binding domains were also noted through in silico studies, LXR-β adopting lesser specificity. We report that 28-HB transactivates LXR genes in the rat tissues.