The Anxiolytic Effect of Polysaccharides from Stellariae Radix through Monoamine Neurotransmitters, HPA Axis, and ECS/ERK/CREB/BDNF Signaling Pathway in Stress-induced Male Rats

Effects of natural source polysaccharides on neurological diseases: A review

With the aging of society and changes in lifestyle, the incidence of neurological diseases (NDs) has been increasing year by year, bringing a heavy burden to patients and society. Although the efficacy of chemical drugs in the treatment of NDs is remarkable, there are problems such as high side effects and high costs. Therefore, finding mild and efficient drugs for NDs treatment has become an urgent clinical need. Natural source polysaccharides (NSPs) are macromolecules with unique bioactivity and low toxicity characteristics, which have great potential to become novel therapeutic agents for NDs. In the present study, the pharmacological activities and potential molecular mechanisms of NSPs to alleviate NDs are systematically reviewed from the perspectives of inflammation, oxidative stress, apoptosis, neuronal cell autophagy, neurotoxicity, and sedation-hypnosis. In addition, the limitations of the existing studies were analyzed and discussed, and the future research direction was suggested. This study may provide scientific basis for the research and development of therapeutic agents for NDs based on NSPs.

Metabolomics Reveal Key Metabolic Pathway Responses to Anxiety State Regulated by Serotonin in Portunus trituberculatus

BACKGROUND

Anxiety refers to the pathological persistence and intensification of emotional responses to danger, affecting health from psychological and physical aspects. Serotonin is an important neurotransmitter involved in the onset of anxiety.

METHODS AND RESULTS

To explore the biological changes in the formation of anxiety in crustaceans under the regulation of serotonin, we applied the open field-like test method for assessing anxiety states of larval Portunus trituberculatus, a highly aggressive crustacean species with a more simple neural structure compared with rodents and mammals. Compared with the control group, serotonin treatment resulted in a significant decrease in the time spent by the larvae in the central zone, suggesting anxiety-like behavior. Clonazepam treatment reversed this result and provided further evidence that the behavior of larval P. trituberculatus displayed anxiety. Moreover, a non-targeted metabolomic analysis found a significant alteration in the metabolites involved in tryptophan metabolism pathways associated with anxiety, including L-kynurenine, N-acetyl serotonin, and serotonin. These metabolites are involved in the serotonin pathway, the kynurenine pathway, and other pathways that affect anxiety through tryptophan metabolism. There were no significant differences in tryptophan metabolism levels between the control and clonazepam treatment groups.

CONCLUSIONS

Our results demonstrate the possible existence of anxiety-like behavior in the larvae of P. trituberculatus from two perspectives. Being a species with a simpler neural structure than that of mammals, the larvae of P. trituberculatus offer a convenient model for studying the mechanisms of anxiety in crustaceans.

Along the microbiota-gut-brain axis: Use of plant polysaccharides to improve mental disorders

With the development of gut microbiota-specific interventions for mental disorders, the interactions between plant polysaccharides and microbiota in the intestinal and their consequent effects are becoming increasingly important. In this review, we discussed the role of plant polysaccharides in improving various mental disorders via the microbiota-gut-brain axis. The chemical and structural characteristics and metabolites of these plant polysaccharides were summarised. Plant polysaccharides and their metabolites have great potential for reshaping gut microbiota profiles through gut microbiota-dependent fermentation. Along the microbiota-gut-brain axis, the consequent pharmacological processes that lead to the elimination of the symptoms of mental disorders include 1) regulation of the central monoamine neurotransmitters, amino acid transmitters and cholinergic signalling system; 2) alleviation of central and peripheral inflammation mainly through the NLRP3/NF-κB-related signalling pathway; 3) inhibition of neuronal apoptosis; and 4) enhancement of antioxidant activities. According to this review, monosaccharide glucose and structure -4-α-Glcp-(1→ are the most potent compositions of the most reported plant polysaccharides. However, the causal structure-activity relationship remains to be extensively explored. Moreover, mechanistic elucidation, safety verification, and additional rigorous human studies are expected to advance plant polysaccharide-based product development targeting the microbiota-gut-brain axis for people with mental disorders.