Banana peel extract improves intestinal motility in constipation model mice by regulating gut microbiota and neurotransmitter levels
Constipation is a common disease of the internal digestive tract, mainly manifested as difficulty in defecation, decreased frequency and irregular, dyspepsia, often accompanied by a variety of complications, such as depression, diabetes and other diseases, age, gender, personal hobbies, drug abuse and other factors can induce constipation. The existing treatment methods mainly include lifestyle intervention, drug therapy, and physical therapy. Traditional laxatives are the most common method of drug treatment, but they have significant side effects, short shelf life, and can also lead to strong drug dependence; Lifestyle intervention has a long intervention period and is difficult to achieve immediate results. Most patients find it difficult to persist, resulting in poor treatment outcomes.
Clinical studies have shown that constipation is usually induced by the slow passage of feces in the intestine, leading to dehydration, hardening, and dryness of the feces. The reasons for its formation are complex, but mainly related to the dysfunction of colonic transport function. Recent studies have shown that there is a certain connection between intestinal transport function and gut microbiota and neurotransmitter disorders, but their correlation is not fully understood, and there is a lack of drug screening research for improving intestinal motility in the treatment of constipation. Therefore, exploring the relationship between intestinal transport function, intestinal microbiota, and intestinal neurotransmitters is of great theoretical value for elucidating the mechanism of constipation and promoting the development of highly effective and low toxicity therapeutic drugs.

Banana peels contain abundant dietary fiber, amino acids, polysaccharides, polyphenols, and unsaturated fatty acids, which have the effect of improving constipation. However, the constipation regulating mechanism of banana peel extract is still unclear, and whether it has the function of improving intestinal motility still needs to be experimentally explored. This study aims to investigate the effect and mechanism of banana peel extract on intestinal motility in constipated mice through oral intervention with banana peel extract, providing a theoretical basis for further development of high-efficiency functional products for preventing and controlling constipation with banana peel extract.

 

Increasing the intake of dietary fiber and drug stimulation has been proven to effectively alleviate constipation, but currently the intervention methods for constipation mainly rely on drug treatment, and satisfactory relief methods have not been found in lifestyle. In this study, the apparent indicators of constipation showed that compared with the blank group, the fecal quantity, fecal water content, and small intestine ink propulsion rate of constipation model mice were significantly reduced. After intervention with banana peel extract and oligofructose, these indicators were significantly restored, and the effect of banana peel extract was significantly better than that of oligofructose. Especially in terms of intestinal motility indicators, the ability to recover to the level of the blank group indicates that the banana peel extract solution has a significant effect on promoting defecation, improving fecal indicators, and intestinal motility. At present, there are relatively many research literature on improving constipation, but they mainly focus on the field of traditional Chinese medicine, and there are relatively few studies on the intervention effects of natural food ingredients. And most studies mainly focus on epigenetic indicators, lacking research on the improvement of intestinal motility. There is also a relative lack of research on the basic mechanisms of constipation occurrence and recovery from the perspectives of gut microbiota and intestinal neurotransmitters.
This study found that banana peel extract has the effects of moistening the intestines, promoting bowel movements, and improving intestinal motility in mice. The potential reason for this is that banana peel extract contains active ingredients such as dietary fiber, capsaicin, and tryptophan, which can regulate intestinal microbiota, regulate neurotransmitters, enhance intestinal motility in mice, and have a good improvement effect on functional constipation. In addition, some scholars have proposed the development of synergistic antibacterial agents by combining plant active ingredients with antibiotics, which can effectively restore the relevant bacterial communities inhibited by antibiotics. The capsaicin contained in banana peels can inhibit the growth of bacteria and fungi, and has a good regulatory effect on gut microbiota, indicating its potential in the application of antibacterial agents.
Existing studies have mostly explored the alleviating effects of intervention substances on constipation from epigenetic indicators, but have not revealed their potential mechanisms. However, some scholars have found that gut derived 5-HT is closely related to intestinal motility. It can control the contraction or relaxation of intestinal muscles by binding to corresponding receptors on intestinal smooth muscle fiber cells, thereby affecting the rate of fecal excretion. But the role of other neurotransmitters in regulating intestinal motility is currently unclear. Through further research, it was found that compared with the blank group, the constipation model mice showed significant differences in intestinal neurotransmitters, except for 5-HT levels, GABA, ACh, and glutamate levels. Among them, glutamate levels were significantly negatively correlated with intestinal motility, indicating that high levels of glutamate in the intestine can inhibit intestinal motility. Banana peel extract can effectively increase 5-HT levels and reduce glutamate levels, thereby enhancing intestinal motility. The results of this study indicate that banana peel extract can intervene in mouse intestinal motility by affecting the levels of intestinal neurotransmitters. In addition, this study also found significant differences in the levels of neurotransmitters in the intestine between the high-dose and low-dose groups of banana peel extract, which may be related to the complex interactions of gut microbiota in the intestine, but the specific reasons remain to be further explored.
The balance of gut microbiota is an important factor in evaluating health, and B/F is a key indicator for determining whether the gut microbiota is imbalanced. Yang et al. found that constipation can cause mutations in B/F values. In this study, the 16S rRNA gene sequencing results showed that at the gate level, the B/F value of the MD group increased by 350.83% compared to the MB group, and banana powder intervention could restore the B/F value of mice to normal levels. Due to the B/F value mutation being a typical characteristic of intestinal microbiota imbalance, intervention with banana peel extract can restore this value to normal levels, indicating that banana peel extract has a regulatory effect on intestinal microbiota imbalance in mice. At the genus level, compared with the MD group, the relative abundance of beneficial bacteria Trabulsiella in the low and high-dose banana peel extract groups increased by 6 and 7 times, respectively. The relative abundance of Trabulsiella in the high-dose oligofructose group increased by 3 times, indicating that Trabulsiella is a key biomarker for constipation and a target bacterial group for banana peel extract and oligofructose intervention in constipation.
The homeostasis of gut microbiota is related to constipation in mice. Functional constipation is often accompanied by weakened colonic motility, which is closely related to the functional levels of intestinal neurotransmitters and the structure of gut microbiota. Diet and gut microbiota metabolites directly or indirectly affect gut function by affecting the enteric nervous system or stimulating receptors of intestinal secretory cells. A high carbohydrate diet can increase the abundance of Ruminococcus, Dorea, and other substances in the intestine. Lachnospiraceae can protect the intestinal health of mice, reduce external environmental damage to the large and small intestines, and improve intestinal permeability. In addition, studies have found that compared to healthy individuals, Parkinson’s patients have lower levels of gut microbiota such as Dorea and Ruminococcus, and higher levels of Oscillospira. At the same time, patients have lower levels of neurotransmitters such as 5-HT and NE, indicating a possible correlation between Dorea, Ruminococcus, and Oscillospira and neurotransmitters such as 5-HT and NE. The correlation analysis of this study found that NE, 5-HT, and Glu were strongly correlated with different bacterial communities such as Enterococcus, Dorea, and Citrobacter, indicating a significant correlation between gut neurotransmitters and the types of gut microbiota. In terms of the correlation between neurotransmitters and intestinal motility, it was found that the small intestine propulsion rate in mice was significantly negatively correlated with the neurotransmitters 5-HT and Glu in the intestine, and the time of the first black stool excretion in mice was significantly positively correlated with 5-HT. The above results indicate that gut microbiota may affect mouse intestinal motility by regulating specific levels of intestinal neurotransmitters, thereby determining the rate of fecal excretion and whether constipation occurs. Nzakizwanayo and Peng et al. also believe that gut microbiota is closely related to neurotransmitters, but they have not yet confirmed the relevant reports or explored the relationship between gut microbiota, gut neurotransmitters, and intestinal motility.
In summary, there is a significant correlation between the gut microbiota and intestinal neurotransmitters in constipation model mice, and intestinal neurotransmitters are significantly correlated with intestinal motility. Banana peel extract can be used as a prebiotic to improve constipation by regulating gut microbiota and neurotransmitter levels, enhancing intestinal motility. However, research on the relationship between gut microbiota and intestinal motility is still in its early stages, and there are many unclear issues that require further in-depth study.
This study found that banana peel extract has a significant improvement effect on the intestinal disorder constipation model mice induced by mixed antibiotic solution. Its mechanism of action may be related to the regulation of certain specific bacterial communities in the mouse gut by banana peel extract, which in turn affects the levels of intestinal neurotransmitters and improves intestinal motility in mice. The results of this study can lay a theoretical foundation for the development of efficient active products for the treatment of constipation.