Exogenous spermidine affects polyamine metabolism in the mouse hypothalamus

Gut microbiota and anti-aging: Focusing on spermidine

The human gut microbiota plays numerous roles in regulating host growth, the immune system, and metabolism. Age-related changes in the gut environment lead to chronic inflammation, metabolic dysfunction, and illness, which in turn affect aging and increase the risk of neurodegenerative disorders. Local immunity is also affected by changes in the gut environment. Polyamines are crucial for cell development, proliferation, and tissue regeneration. They regulate enzyme activity, bind to and stabilize DNA and RNA, have antioxidative properties, and are necessary for the control of translation. All living organisms contain the natural polyamine spermidine, which has anti-inflammatory and antioxidant properties. It can regulate protein expression, prolong life, and improve mitochondrial metabolic activity and respiration. Spermidine levels experience an age-related decrease, and the development of age-related diseases is correlated with decreased endogenous spermidine concentrations. As more than just a consequence, this review explores the connection between polyamine metabolism and aging and identifies advantageous bacteria for anti-aging and metabolites they produce. Further research is being conducted on probiotics and prebiotics that support the uptake and ingestion of spermidine from food extracts or stimulate the production of polyamines by gut microbiota. This provides a successful strategy to increase spermidine levels.

Exploration of the Antioxidant Effect of Spermidine on the Ovary and Screening and Identification of Differentially Expressed Proteins

Spermidine is a naturally occurring polyamine compound that has many biological functions, such as inducing autophagy and anti-inflammatory and anti-aging effects. Spermidine can affect follicular development and thus protect ovarian function. In this study, ICR mice were fed exogenous spermidine drinking water for three months to explore the regulation of ovarian function by spermidine. The results showed that the number of atretic follicles in the ovaries of spermidine-treated mice was significantly lower than that in the control group. Antioxidant enzyme activities (SOD, CAT, T-AOC) significantly increased, and MDA levels significantly decreased. The expression of autophagy protein (Beclin 1 and microtubule-associated protein 1 light chain 3 LC3 II/I) significantly increased, and the expression of the polyubiquitin-binding protein p62/SQSTM 1 significantly decreased. Moreover, we found 424 differentially expressed proteins (DEPs) were upregulated, and 257 were downregulated using proteomic sequencing. Gene Ontology and KEGG analyses showed that these DEPs were mainly involved in lipid metabolism, oxidative metabolism and hormone production pathways. In conclusion, spermidine protects ovarian function by reducing the number of atresia follicles and regulating the level of autophagy protein, antioxidant enzyme activity, and polyamine metabolism in mice.

Expression of polyamines and its association with GnRH-I in the hypothalamus during aging in rodent model

GnRH-I and GnIH are the key neuropeptides that regulate the hypothalamic-pituitary-gonadal axis in mammals during aging. Polyamines are important aliphatic amines that are expressed in the brain and show variation with aging. The present study demonstrates evidence of variation in the level of expression of polyamines, GnRH-I and GnIH in the hypothalamus of female mice during aging. The study also suggests regulatory effects of polyamines over expression of the hypothalamic GnRH-I. The study shows a significant positive correlation between polyamines, its associated factors and GnRH-I along with significant negative correlation between polyamines, its associated factors and GnIH. This is the first study to report the effect of polyamines along with lactate or TNF-α or both on GnRH-I expression in GT1-7 cell line. TNF-α and lactate significantly decreased hypothalamic GnRH-I mRNA expression in GT1-7 cells when treated for 24 h. Polyamines (putrescine and agmatine) in contrast, significantly increased GnRH-I mRNA expression in GT1-7 cells when treated for 24 h. Also, polyamines increased GnRH-I mRNA expression when treated in presence of TNF-α or lactate thereby suggesting its neuro-protective role. This study also found 3809 differentially expressed genes through RNA-seq done between the hypothalamic GT1-7 cells treated with putrescine only versus TNF-α and putrescine. The present study suggests for the first time that putrescine treatment to TNFα-primed GT1-7 cells upregulates GnRH-I expression via regulation of several pathways such as calcium ion pathway, estrogen signaling, clock genes as well as regulating other metabolic process like neuronal differentiation and neurulation.