Study on the protective activity of bamboo and willow polysaccharides on sensory hair cells based on zebrafish model
Aminoglycoside drugs are antibiotics containing amino sugar molecules in their chemical structure, commonly used to treat infections caused by Gram negative bacteria and have a wide range of applications. However, these drugs have strong ototoxicity and nephrotoxicity. Research has found that its nephrotoxicity can be alleviated through hydration therapy. However, there is currently no effective treatment for its ototoxicity, and it is crucial to develop corresponding preventive and therapeutic drugs. The pathogenesis of aminoglycoside induced hearing loss is currently not fully understood, but research has found that sensory hair cells in the inner ear play a key role in it. This cell is a type of terminally differentiated cell located in the inner ear of mammals, and once lost, it cannot be regenerated. After entering hair cells, aminoglycoside drugs can induce a large production of reactive oxygen species (ROS). These ROS generated by the action of aminoglycoside drugs can promote oxidative damage to hair cells and induce their apoptosis. Therefore, reducing the production of ROS in sensory hair cells has become one of the directions for the development of drugs for the prevention and treatment of aminoglycoside induced hearing loss. Zebrafish is an internationally recognized new vertebrate model organism with small size, rapid growth, strong reproductive ability, in vitro fertilization and development, and transparent embryos. Compared with humans, zebrafish exhibit extremely high conservation in physiological structure, signaling pathways, protein function, and other aspects. Zebrafish have inner ear sensory hair cells and lateral hair cells that are highly homologous to humans. When it reaches the 5th day of development (dpf), the aforementioned hair cells have already fully developed. Due to the transparency of zebrafish during early development, in vivo imaging technology allows for direct real-time observation of the toxic effects of the test sample on hair cells. Therefore, zebrafish has become an important model organism for studying drugs for the prevention and treatment of drug-induced hearing loss. In previous studies, it was found that bamboo and willow contain a polysaccharide with antioxidant properties, which is composed of 8.72% xylose, 14.87% L (+) – rhamnose, 3.22% D (-) – glucuronic acid, 5.45% D-galacturonic acid, 54.86% D-arabinose, and 13.05% mannose. Based on the close relationship between antioxidant and sensory hair cell damage protection, zebrafish was selected as the experimental animal in this experiment, and kanamycin, a representative aminoglycoside antibiotic, was used as the damage drug. The protective activity and mechanism of sensory hair cells of bamboo and willow polysaccharides discovered independently were preliminarily studied, aiming to provide theoretical basis and experimental data for further understanding the prevention and treatment of drug-induced hearing loss.
Kanamycin, as one of the representative drugs of aminoglycoside antibiotics, has a low price, wide antibacterial spectrum, stable properties, and a wide range of applications. But it has strong ototoxicity. The mechanism of action of kanamycin induced deafness is relatively complex, and the excessive accumulation of ROS in the sensory hair cells of the inner ear plays an important role. Antioxidants can to some extent prevent and treat kanamycin induced sensory hair cell damage. Based on this, this project takes the independently discovered bamboo and willow polysaccharides with antioxidant activity as the research object, and applies the zebrafish model to conduct preliminary research on their sensory hair cell protective activity.
Research has found that when bamboo and willow polysaccharides at concentrations of 30, 40, or 50 μ g/ml are applied alone to zebrafish, the cumulative hatching rate of zebrafish is higher than 98%, the cumulative mortality rate is lower than 15%, and the heart rate is between 198-200 beats per minute. Although the cumulative mortality rate of zebrafish was slightly higher in the 40 μ g/ml treatment group, statistical testing showed that there were no statistically significant differences in the cumulative hatching rate, mortality rate, and heart rate of the three groups of zebrafish (30, 40, and 50 μ g/ml) compared to the blank control group. This result suggests that bamboo and willow polysaccharides have no significant toxicity or teratogenic effects on zebrafish. Further research has found that when polysaccharides from bamboo and willow are combined with kanamycin, there is no significant toxicity or teratogenic effect on zebrafish. However, at this concentration, the polysaccharide has significant protective activity against kanamycin induced sensory hair cell damage, and can effectively reduce the accumulation of kanamycin induced ROS in hair cells and inhibit the occurrence of hair cell apoptosis. ROS, as a single electron reduction product of oxygen in the body, is generated after electrons leak from the respiratory chain and consume about 2% of oxygen. ROS inside the body is not always harmful. Moderate ROS can promote repair, immunity, growth, and survival. However, under pathological conditions, the dynamic balance between ROS production and clearance can be disrupted. Prolonged excessive accumulation of ROS often causes damage to biomolecules such as proteins, nucleic acids, polysaccharides, and lipids, putting cells in an oxidative stress state and inducing apoptosis. This study found that bamboo and willow polysaccharides with antioxidant activity in vitro can also exert their antioxidant effects in sensory hair cells. This polysaccharide can alleviate oxidative damage in sensory hair cells by reducing the level of ROS, and ultimately inhibit kanamycin induced apoptosis, providing a protective effect on hair cells. Moreover, as the polysaccharide does not have significant toxicity or teratogenic effects, the above results suggest that bamboo and willow polysaccharides have certain potential applications in the field of auditory protection.
Polysaccharides derived from natural products are a class of structurally complex polymer compounds. Numerous studies have confirmed that polysaccharides typically possess antioxidant activity, which is closely related to the content of mannose, galactose, and uronic acid in polysaccharides. For example, mannose, galactose, and glucuronic acid are all prone to interact with ROS, leading to glycosidic bond cleavage or oxidation of glucuronic acid. The bamboo and willow polysaccharides used in this study contain approximately 130.5% mannose, 3.22% glucuronic acid, and 5.45% D-galactouronic acid. It is speculated that the sensory hair cell protective activity of bamboo and willow polysaccharides may be determined by their monosaccharide composition. Both mannose and uronic acid in bamboo and willow polysaccharides contribute to their rapid reduction of ROS content in sensory hair cells, thereby exhibiting protective activity against sensory hair cells.
Bamboo and willow grow rapidly, have strong stress resistance, high economic benefits, and strong adaptability. In recent years, their planting area in China has rapidly expanded. At present, research on bamboo and willow mainly focuses on drought resistance, salt alkali tolerance, disease and pest control, and there are few reports on the efficacy of their extracts. This study confirmed through in vivo experiments that bamboo and willow polysaccharides have a certain protective activity against sensory hair cell damage induced by aminoglycoside antibiotics, and found that this protective activity is closely related to the antioxidant activity of bamboo and willow polysaccharides. The data obtained from this study can provide new experimental data for the prevention and treatment of drug-induced hearing loss, and help broaden the application fields of bamboo and willow, promoting their high-value applications.