The oocyte is the beginning of human life, it is an immature egg cell that eventually matures into an egg. However, oocyte quality decreases as women age or due to factors such as obesity , and low-quality oocytes are the main cause of low fertility in obese women. However, how to improve the quality of oocytes in obese women is a challenge for scientists.

Recently , a study titled Administration of nicotinamide mononucleotide improves oocyte quality of obese mice was published in Cell proliferation. The study found that  supplementation of nicotinamide adenine dinucleotide (NAD+) precursor nicotinamide mononucleoside Acid (NMN) can effectively improve ovarian inflammation, improve oocyte quality and restore offspring body weight in obese female mice .

 
The researchers selected 3-week-old female mice and 11 - week-old male mice to establish a mouse model of obesity with a high-fat diet and validated by weight recording, fasting blood glucose test, and oral glucose tolerance test, dietary intervention 1 For 2 weeks, N MN supplements were injected for 10 consecutive days to detect the expression of ovarian development-related genes and inflammation-related genes , fat size of abdominal adipose tissue , reactive oxygen species level of oocytes, spindlechromosome structure, mitochondrial Function, actin dynamics, and DNA damage , compared with statistical results showing：

1. A high- fat diet -induced obesity mouse model was successfully established
The FGB value of the high-fat diet (HFD) group was consistently higher than that of the normal diet ( ND ) group , in addition, the OGTT results showed that the high-fat diet ( HFD ) group mice were glucose intolerant .
 

( Figure 1 )

2. NMN can improve metabolic abnormalities in HFD mice
Supplementation with NMN supplementation reduced fat volume in mice in the high-fat diet ( HFD ) group , and the results suggest that NMN has a protective effect on abnormal metabolism in mice in the high-fat diet ( HFD ) group .
 

( Figure 2 )

3. NMN improves ovarian quality in HFD mice
NMN can improve ovarian quality in high-fat diet ( HFD ) mice by regulating the expression of key genes related to ovarian follicle development ( Bmp4 , Lhx8 ) and inflammation.
 

( Figure 3 )

4. NMN reduces oocyte division defects and DNA damage in HFD mice
NMN can reduce the high frequency of spindle defects and chromosomal misalignments caused by high-fat diet ( HFD ) , reduce γH2A.X signaling, and ameliorate high - fat diet ( HFD ) -induced DNA damage by reducing Bax expression .
 

( Figure 4 )

5. NMN can improve the quality of oocytes
NMN can repair the down-regulated expression of antioxidant SOD1 in high- fat diet ( HFD ) group , improve the distribution of mitochondria, and can improve the quality of oocytes by maintaining the integrity of the cytoskeleton.
 

( Figure 5 )

6. NMN can restore lipid droplet distribution in HFD mice
high-fat diet ( HFD ) group oocytes was slightly higher than that in normal diet ( ND ) group oocytes, and NMN supplementation could reduce the fluorescence intensity of lipid droplets .
 

( Figure 6 )

7. NMN restores body weight in offspring of HFD mice
birth weight of the offspring of the high-fat diet ( HFD ) group was significantly lower than that of the normal diet ( ND ) group, and supplementation with NMN supplementation restored the birth weight of the offspring of the HFD group .
 

( Figure 7 )

In this study, researchers demonstrated through mouse experiments that NMN had the ability to improve the quality of oocytes in obese female mice induced by high-fat diet, and revealed that NMN could restore mitochondrial function and reduce ROS accumulation in obese female mouse oocytes . , DNA damage and underlying mechanisms of lipid droplet distribution. Therefore, this study will provide a potential therapeutic strategy for improving fertility problems caused by obesity in women .

references：
1.Wang L, Chen Y, Wei J, et al. Administration of nicotinamide mononucleotide improves oocyte quality of obese mice. Cell Prolif. 2022; e13303. doi10. 1111cpr.13303