Indian Journal of Animal Research

  • Chief EditorK.M.L. Pathak

  • Print ISSN 0367-6722

  • Online ISSN 0976-0555

  • NAAS Rating 6.50

  • SJR 0.263

  • Impact Factor 0.4 (2024)

Frequency :
Monthly (January, February, March, April, May, June, July, August, September, October, November and December)
Indexing Services :
Science Citation Index Expanded, BIOSIS Preview, ISI Citation Index, Biological Abstracts, Scopus, AGRICOLA, Google Scholar, CrossRef, CAB Abstracting Journals, Chemical Abstracts, Indian Science Abstracts, EBSCO Indexing Services, Index Copernicus
Submit

Full Research Article

Ovariectomy May be Responsible for Subcutaneous Fat Deposition by Altering Hepatic Lipid Metabolism in Female Pigs

Zhenqing Yang1,2, Caizai Zhang1,2, Jian Yuan1,2, Zhimin Wu3, Xiaoli Sh1,2, Zheng Ao1,2,*
1Key Laboratory of Animal Genetics, Breeding and Reproduction in the Plateau Mountainous Region, Ministry of Education, College of Animal Science, Guizhou University, Guiyang-550025, China.
2Guizhou Provincial Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science, Guizhou University, Guiyang-550025, China.
3Bureau of Agriculture and Rural of Zhenning County, Zhenning-561200, China.

ABSTRACT

Background: Emerging experimental and human evidence has linked decreased ovary-origin hormones and obesity and various metabolic diseases through affecting homeostasis of glucose and lipid metabolism, but the underlying mechanisms remain unclear. 

Methods: To investigate the effect removal of ovary on the growth and fat deposition of female pigs. In this work, we compared the average backfat thickness, hepatic lipid metabolism indexes and hepatic transcriptome between ovariectomized (OVX) and sham-operated (Sham) female pigs.

Result: Results showed that the OVX females had remarkably increased backfat thickness, total cholesterol and triglyceride levels in the liver, whereas serum estradiol levels and hepatic high-density lipoprotein-cholesterol levels presented significantly lower levels compared with those in the sham females. A total of 414 differentially expressed genes (DEGs) identified by transcriptome analysis between the OVX and Sham livers, of which 130 and 314 genes were up-and down-regulated in the OVX livers, respectively. Pathway analysis showed that these DEGs were mainly involved in PPAR signaling pathway, insulin signaling pathway, insulin resistance, hippo signaling pathway. Besides, twelve DEGs involved in glucose and lipid metabolism were screened out, including PCK1, FDPS, HMGCR, HMGCS1, HMGCS2, PPP1R3B, PPP1R3C, ACAT2, SIK1, OGDHL, SOCS2 and IGFBP1. These results indicate that hormones generated by ovaries may play important roles in subcutaneous fat deposition by mediating hepatic glucose and lipid metabolism in female pigs.

INTRODUCTION

Clinical studies have shown that cessation of ovarian hormone production in menopause suffered from increased body weight gain, visceral adiposity and disorders associated with obesity-related comorbidities (Boldarine et al., 2020). The role of estrogens in metabolic, immune and inflammatory processes has been elaborated in both humans and rodents, although the complexity by which these effects occur is not fully understood. Previous researches in animals indicated that removal of ovaries by ovariectomy (OVX) resulted in significant changes in production performance, slaughter performance, blood biochemical indices, fat metabolism, bone development and immunity (Amorim et al., 2016). Elevated evidence demonstrated that OVX has an apparent effect on lipid metabolism, which favors lipogenesis but impairs fatty acid oxidation and induces a pro-inflammatory state in rats (Boldarine et al., 2020).
       
Estrogen biosynthesis mainly originates from the ovaries, which plays an important role in regulating reproductive activity, tissue metabolism and various pathophysiologic processes. All estrogen receptors are predominantly expressed in reproductive organs such as prostate, ovary, uterus, testis and breast, as well as highly expressed in the liver of humans and experimental animals (Ruggiero and Likis, 2002). In animals, OVX leaded to insulin resistance and increased susceptibility to the deleterious effects of a high-fat diet, which can be prevented by estrogen supplementation to ensure physiologic levels of this hormone (Stubbins et al., 2012).
       
The liver is a critical organ in regulating lipid metabolism via secretion and excretion of bile. Accumulated studies have shown that estrogen replacement therapy greatly reduced the incidence of liver lipid deposition, suggesting that estrogen has a protective effect on hepatic lipid metabolism (Kur et al., 2020). So far, pigs are regarded as the most ideal organ xenograft donor of human beings because they have similar organ size, physiological metabolism and immune system (Xi et al., 2022). Hence, we explored the effect of OVX on hepatic lipid metabolism of sows by comparing the hepatic gene expression by RNA sequencing in the present study.

MATERIALS AND METHODS

Sample collection
 
A pool of 20 Tibetan-ginger crossbred female pigs with similar age, genetic background, body weight and health were selected. Ten pigs were surgically removed ovary by bilateral ovariectomy (OVX) after induction of anesthesia (xylazine, 2.0 mg/kg bw) at postnatal 45 days of age. Remaining female pigs were treated as sham-operated controls, which underwent the entire surgery except for the removal of ovaries (Horigan et al., 2009). All pigs were fed with a standard diet and had free access to water until 12 h of fasting at the age of 10 months and then 5 mL of blood was collected from the jugular vein and then centrifuged at 2,600 rpm/min for 5 min after 40 min of resting and then the serum was collected. After slaughtering, the backfat thickness of the left carcass of sows at the thickest part of the shoulder the last rib and the lumbar-recommending vertebrae were measured and liver tissues were collected to perform RNA sequencing and biochemical indexes analysis. All samples were immediately frozen in liquid nitrogen and stored at -80°C until use.
 
Biochemical analysis
 
The levels of total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) in the liver were measured using commercially available kits (Nanjing Jiancheng Bioengineering Institute, Nanjing, China). Serum estradiol level was analyzed with an enzyme immunoassay test kit (Ruixin Biotechnology Limited, Fujian, China) according to the protocol and manufacturer’s instructions.
 
Total RNA extraction, library construction and sequencing
 
Total RNA was extracted from liver tissues (OVX, n = 4; Sham, n = 4) for RNA sequencing using a total RNA Kit (Omega, Norcross, GA, USA) according to the manufacturer’s instructions. Raw data were deposited in the NCBI Sequence Read Archive database under accession number PRJNA1033387. The library preparations were sequenced on an Illumina Novaseq 6000 and 150 bp paired-end reads were generated. Low-quality reads with junctions were removed from the original sequenced sequences to obtain clean reads for subsequent analysis. Clean reads were aligned with the designated genome using HISAT2 software to obtain the positional information of the reads in the Sus scrofa reference genome (version: Scrofa11.1). Fragments per Kilobase Million Mapped Reads (FPKM) value of each gene then was calculated based on the length of the gene and reads count mapped to this gene. Differential expression analysis of genes were then performed using DESeq2 and the P-value <0.05, |log2 (fold change)| >1 were used as the criteria for screening differentially expressed genes (DEGs). KOBAS (http://kobas.cbi.pku.edu.cn/) was used to perform the GO enrichment and KEGG pathway analysis.
 
Quantitative real time polymerase chain reaction (qRT PCR) validation
 
Primers information was shown in Table 1. The qRT-PCR reaction was performed using SYBR Select Master Mix on the Quant Studio™3 Flex qRT-PCR System (Thermo Fisher Scientific Waltham, MA, USA). The reaction program was as follows: 50°C for 2 min UDG enzyme activation, 95°C for 2 min pre-denaturation; the PCR instrument was cycled 40 times (95°C for 15 s, 60°C for 15 s, 72°C for 1 min); and the lysis curve conditions: 95°C for 15 s, 60°C for 1 min and 95°C for 15 s. The relative expression of the genes was calculated using the 2-ΔΔCt method, with results run in quadruplicate.
 

Table 1: The primers used for quantitative PCR.

RESULTS AND DISCUSSION

Comparison of backfat thickness and serum estradiol levels between OVX and Sham groups
 
We observed that the backfat thickness of female pigs in the OVX group was remarkably higher than that in the Sham group (P<0.05), while the estradiol level was significantly lower than that in the sham-operated pigs (472.49±27.45 ng/L VS. 238.71±11.30 ng/L) (P<0.05, Fig 1), which indicates that removal of ovary lead to subcutaneous fat accumulation in pigs. Given that the liver was essential to regulate glucose and lipid metabolism, alterations in hepatic physiological functions may be responsible for obesity of pigs.
 

Fig 1: Differences in body weight, average backfat thickness and serum estradiol levels between the OVX and the Sham females.


 
Comparison of hepatic lipid metabolism indexes and histopathology between OVX and sham groups
 
Compared with sham-operated controls, OVX pigs exhibited markedly increased levels of TC and TG and reduced levels of HDL-C (P<0.05, Fig 2). These results were consistent with previous studies in mice and rats (Zhu et al., 2023). High TG caused by any reason can lead to hepatic steatosis (Miller 2000). It has been reported that the plasma TC was increased in the aging humans and rodents since their physiological function in eliminating cholesterol decreased (Lei et al., 2021). Several studies have demonstrated that ectopic accumulation of lipid within liver could specifically cause hepatic insulin resistance in humans and rodents (Fabbrini et al., 2009). A previous study found that ovariectomized mice had increased monounsaturated fatty acid levels of hepatic triglyceride in the liver (Jackson et al., 2011).
 

Fig 2: Hepatic parameters of lipid metabolism in ovariectomized pigs compared to sham-operated controls.


       
Histomorphologic analysis showed that OVX females had mor1e lipid drops accumulated in the livers compared to Sham pigs (Fig 3). OVX mice commonly demonstrate increased body weight owing to excessive fat accumulation, as well as increased liver lipid accumulation, leading to fatty liver (Nanashima et al., 2020). Hepatic cholesterol accumulation is driven by a deeply deranged cellular cholesterol homeostasis, characterized by elevated cholesterol synthesis and uptake from circulating lipoproteins and by a reduced cholesterol excretion (Musso et al., 2013).
 

Fig 3: The histomorphology of livers from ovariectomized and Sham-operated control pigs via H and E staining (n = 6 livers for per group).


 
Transcriptomic analysis of liver tissues of OVX and Sham groups
 
In the present study, average number of raw reads, clean reads and mapped reads in the liver of Sham and OVX groups were shown in Supplementary Table 1. By alignment analysis, 21,832 genes commonly expressed in the liver tissues of the OVX and Sham female pigs. A total of 414 genes were identified as differentially expressed genes (DEGs) between two groups under the thresholds of P<0.05 and |log2Foldchange| >1, of which 130 and 314 DEGs were up-regulated and down-regulated in the OVX group.  Hierarchical clustering showed a very clear separation of DEGs between the OVX and Sham groups (Fig 4).
 

Supplementary Table 1: Basic information on transcriptome sequencing of each liver tissue.


 

Fig 4: Heatmap for clustering analysis of DEGs.


       
Gene ontology (GO) enrichment and KEGG pathway analysis of all DEGs were carried out between the two groups (Fig 5). GO enrichment analysis revealed that main enriched biological processes were cell-cell signaling, G protein-coupled adenosine receptor signaling pathway, cholesterol biosynthetic process. For GO cellular components, DEGs involved in the extracellular matrix, perinuclear region of cytoplasm, integral component of plasma membrane and integrin complex were most strongly represented. In the category of GO molecular function, DEGs were mainly associated with metallocarboxy peptidase activity, calcium ion binding, creatine kinase activity and protein kinase activator activity. KEGG pathway analysis showed that PPAR signaling pathway, insulin signaling pathway, hippo signaling pathway, bile secretion seemed to be the obvious core metabolic pathways. Furthermore, we screened out twelve DEGs involved in glucose and lipid metabolism, including PCK1, FDPS, HMGCR, HMGCS1, HMGCS2, PPP1R3B, PPP1R3C, ACAT2, SIK1, OGDHL, SOCS2 and IGFBP1 (Table 2). The qRT-PCR analysis revealed that mRNA expression levels of these genes were consistent with the results of RNA-Seq (P<0.05, Fig 6).
 

Fig 5: GO enrichment and KEGG pathway analysis of DEGs in the liver tissues between OVX and sham groups.


 

Table 2: List of differentially expressed genes involved in glucose and lipid metabolism between the OVX and sham livers.


 

Fig 6: Validation of DEGs involved in lipid metabolism in liver tissues between OVX and Sham groups by qRT-PCR.


       
PPAR are ligand-activated transcriptional modulators with well-documented functions in hepatic, whole-body energy homeostasis, lipid and glucose metabolism and inflammatory responses (Berthier et al., 2021). A study by Hu et al., (2021) highlighted that hepatic lipid metabolism in the hyperlipidemia model rats could be regulated by atorvastatin ester through the PPAR signaling pathway and HMGCR expression. In the present study, we observed the OVX females had reduced expression levels of PCK1 and HMGCS2, whereas increased levels of HMGCR and HMGCS1 compared with the Sham females. Accumulating evidence indicates that PCK1, the rate-limiting enzyme in gluconeogenesis, regulates not only glucose homeostasis but also lipogenesis by activating sterol-regulatory element-binding proteins (Ye et al., 2023). A recent study showed that PCK1 deficiency stimulated lipogenic gene expression and lipid synthesis and activated the RhoA/PI3K/AKT pathway by increasing intracellular GTP levels, increasing secretion of platelet-derived growth factor-AA and promoting hepatic stellate cell activation (Ye et al., 2023). 
       
The steady state of the cholesterol metabolism depends on a complex network involving cholesterol uptake, synthesis, transport and excretion (Musso et al., 2013). Many clinical and basic research have confirmed that lipid metabolism is bound up with cholesterol synthesis (Luo et al., 2023). Both HMGCS and HMGCR are the two key rate-limiting enzymes in cholesterol synthesis (Hu et al., 2021). A study conducted on OVX mice model suggested that the expression level of HMGCR related with cholesterol metabolism also significantly increased in the liver of ovariectomized mice compared with sham mice (Lei et al., 2021). Besides, several noncoding RNA has been found to regulating hepatic cholesterol and lipid metabolism by targeting HMGCR (Sun et al., 2015). Additionally, in cholesterol metabolism, ACAT2 promotes the secretion of cholesteryl ester-enriched very low-density lipoproteins by the liver and lacking hepatic ACAT2 can prevent dietary cholesterol-driven hepatic steatosis in mice (Alger et al., 2010). Hence, OVX females had elevated ACAT2 expression may be related to increase of hapetic TC levels.
       
In the liver, two major subunits, protein phosphatase 1 regulatory subunit 3B(PPP1R3B) and regulatory subunit 3C (PPP1R3C) are expressed at approximately equivalent levels and together facilitate the storage of hepatic glycogen. It has been confirmed that overexpression of PPP1R3B lead to increase of liver glycogen in human cell lines and in mice (Agius, 2015). Furthermore, López-Soldado et al., (2015) found that PPP1R3C transgenic mice increased hepatic glycogen and improved glucose and insulin sensitivity.  A survey proved that hepatic PPP1R3C mRNA expression in diabetic mice was increased compared with that in control mice, suggesting that the abnormally high expression of PPP1R3C in livers may be one of the main causes of hyperglycemia in diabetes (Ji et al., 2019). Therefore, the expression levels of PPP1R3B and PPP1R3C in the livers of OVX females were upregulated in this study, which may imply ovariectomy affects liver glucose metabolism.
       
Salt-inducible kinase 1 (SIK1) belongs to the serine-threonine kinase family and also is an AMPK-related protein kinase (Darling and Cohen, 2021). A recent study reported that the overexpression of SIK1 in the liver of the rats could downregulate the expression of gluconeogenic genes (Song et al., 2019). In primary mouse hepatocytes, forced SIK1 expression not only promoted gluconeogenesis but also suppressed lipogenesis (Wang et al., 2020). Consistent with this, data from Zhang et al., (2017) demonstrate that SIK1 expression is inversely correlated with the expression of lipogenic molecules and lipid biosynthesis. In the present study, downregulation of SIK1 in the OVX livers may facilitate gluconeogenic process.
       
Oxoglutarate dehydrogenase-like (OGDHL) participates in regulating the degradation of glucose and glutamate (Bunik and Degtyarev 2008). A study conducted on hepatocellular carcinoma suggested that silencing of OGDHL result in decrease of lipogenesis (Dai et al., 2020), so upregulation of OGDHL may be associated with elevated triglyceride levels.
       
Insulin-like growth factor binding protein 1 (IGFBP1), a binding protein with a high affinity to insulin-like growth factors, mainly produced by hepatocytes and is proved to be associated with glucose regulation and insulin resistance. IGFBP1 treatment significantly ameliorated hepatic steatosis by interacting with ITGB1 and suppressed inflammation by inhibiting NF-κB and ERK signaling pathways (Pan et al., 2021). Previous research has indicated that reduced levels of serum IGFBP1 are commonly observed in obesity, hyperinsulinemia and nonalcoholic fatty liver disease (NAFLD) (Graffigna et al., 2009). Furthermore, as one of the suppressors of cytokine signaling (SOCS) family, it has been clarified that SOCS2 participated in hepatic steatosis and NAFLD (Yuan et al., 2016). Recent research published demonstrated that SOCS2 plays a role in inhibiting inflammation and apoptosis in macrophages during nonalcoholic steatohepatitis through the NF-κB and inflammasome signaling pathways (Li et al., 2021). Therefore, decreased expression levels of IGFBP1 and SOCS2 in the OVX livers may increase the risk of hepatic steatosis.

CONCLUSION

In conclusion, ovariectomy resulted in increase of backfat thickness and lipid accumulation in hepatocytes. Transcriptomic analysis suggested that ovariectomy altered expression of important genes and pathways involved in glucose and lipid metabolism to affect hepatic lipid homeostasis, which may be associated with obesity of OVX pigs. The present study provides valuable information for understanding the ovary-origin hormones roles in hepatic lipid metabolism and fat deposition of female pigs.

ACKNOWLEDGEMENT

The present study was supported by  two grants received from the Department of Science and Technology of Guizhou Province, China (No. QKHJC-ZK[2021]YB166 and No. QKHZC [2021] No. General150), the China Scholarship Council (No. LJM [2021]109) and the Youth Science and Technology talent Development Project of Education Department of Guizhou Province, China (No. QJHKYZ [2021]081), the project of Guizhou seed industry development (No. QNJC [2022]10).
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All animal procedures for experiments were approved by the Institutional Animal Care and Use Committee of Guizhou University, Guiyang, PR China (EAE-GZU-2021-T053).

CONFLICT OF INTEREST

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.

REFERENCES


  1. Agius, L. (2015). Role of glycogen phosphorylase in liver glycogen metabolism. Mol. Aspects Med. 46: 34-45.

  2. Alger, H.M., Brown, J.M., Sawyer, J.K., Kelley, K.L., Shah, R., Wilson, M.D., Willingham, M.C., Rudel, L.L. (2010). Inhibition of acyl-coenzyme a: Cholesterol acyltransferase 2 (ACAT2) prevents dietary cholesterol-associated steatosis by enhancing hepatic triglyceride mobilization. J. Biol. Chem. 285(19): 14267-14274.

  3. Amorim, A., Rodrigues, S., Pereira, E., Valentim, R., Teixeira, A. (2016). Effect of caponisation on physicochemical and sensory characteristics of chickens. Animal. 10(6): 978- 986.

  4. Berthier, A., Johanns, M., Zummo, F.P., Lefebvre, P., Staels, B. (2021). PPARs in liver physiology. Biochim Biophys Acta Mol Basis Dis. 1867(5): 166097. doi: 10.1016/j.bbadis. 2021.166097.

  5. Boldarine, V.T., Pedroso, A.P., Brandão-Teles, C., LoTurco, E.G., Nascimento, C., Oyama, L.M., Bueno, A.A., Martins-de- Souza, D., Ribeiro, E.B. (2020). Ovariectomy modifies lipid metabolism of retroperitoneal white fat in rats: A proteomic approach. Am. J. Physiol Endocrinol Metab. 319(2): E427-E437.

  6. Bunik, V.I. and Degtyarev, D. (2008). Structure-function relationships in the 2-oxo acid dehydrogenase family: Substrate-specific signatures and functional predictions for the 2-oxoglutarate dehydrogenase-like proteins. Proteins. 71(2): 874- 890.

  7. Dai, W., Xu, L., Yu, X., Zhang, G., Guo, H., Liu, H., Song, G., Weng, S., Dong, L., Zhu, J., Liu, T., Guo, C., Shen, X. (2020). OGDHL silencing promotes hepatocellular carcinoma by reprogramming glutamine metabolism. J. Hepatol. 72(5): 909-923.

  8. Darling, N.J., Cohen, P. (2021). Nuts and bolts of the salt-inducible kinases (SIKs). Biochem J. 478(7): 1377-1397.

  9. Fabbrini, E., Magkos, F., Mohammed, B.S., Pietka, T., Abumrad, N.A., Patterson, B.W., Okunade, A., Klein, S. (2009). Intrahepatic fat, not visceral fat, is linked with metabolic complications of obesity. Proc. Natl. Acad. Sci. U S A. 106(36): 15430-15435.

  10. Graffigna, M.N., Belli, S.H., de Larrañaga, G., Fainboim, H., Estepo, C., Peres, S., García, N., Levalle, O. (2009). Insulin-like growth factor-binding protein-1: A new biochemical marker of nonalcoholic fatty liver disease? Acta Gastroenterol Latinoam. 39(1): 30-37.

  11. Horigan, K.C., Trott, J.F., Barndollar, A.S., Scudder, J.M., Blauwiekel, R.M., Hovey, R.C. (2009). Hormone interactions confer specific proliferative and histomorphogenic responses in the porcine mammary gland. Domest. Anim. Endocrinol. 37(2): 124-138.

  12. Hu, N., Chen, C., Wang, J., Huang, J., Yao, D., Li, C. (2021). Atorvastatin ester regulates lipid metabolism in hyperlipidemia rats via the PPAR-signaling pathway and HMGCR expression in the liver. Int J. Mol. Sci. 22(20): 11107. doi: 10.3390/ ijms222011107.

  13. Jackson, K.C., Wohlers, L.M., Valencia, A.P., Cilenti, M., Borengasser, S.J., Thyfault, J.P., Spangenburg, E.E. (2011). Wheel running prevents the accumulation of monounsaturated fatty acids in the liver of ovariectomized mice by attenuating changes in SCD-1 content. Appl. Physiol. Nutr. Metab. 36(6): 798-810.

  14. Ji, X., Wang, S., Tang, H., Zhang, Y., Zhou, F., Zhang, L., Zhu, Q., Zhu, K., Liu, Q., Liu, Y., Wang, X., Zhou, L. (2019). PPP1R3C mediates metformin-inhibited hepatic gluconeogenesis. Metabolism. 98: 62-75.

  15. Kur, P., Kolasa-Wołosiuk, A., Misiakiewicz-Has, K., Wiszniewska, B. (2020). Sex hormone-dependent physiology and diseases of liver. Int J. Environ Res Public Health. 17(8): 2620. doi: 10.3390/ijerph17082620.

  16. Lei, Z., Wu, H., Yang, Y., Hu, Q., Lei, Y., Liu, W., Nie, Y., Yang, L., Zhang, X., Yang, C., Lin, T., Tong, F., Zhu, J., Guo, J. (2021). Ovariectomy impaired hepatic glucose and lipid homeostasis and altered the gut microbiota in mice with different diets. Front Endocrinol (Lausanne). 12: 708838. doi: 10.3389/fendo.2021.708838.

  17. Li, S., Han, S., Jin, K., Yu, T., Chen, H., Zhou, X., Tan, Z., Zhang, G. (2021). SOCS2 suppresses inflammation and apoptosis during NASH progression through limiting NF-êB activation in macrophages. Int J. Biol. Sci. 17(15): 4165-4175.

  18. López-Soldado, I., Zafra, D., Duran, J., Adrover, A., Calbó, J., Guinovart, J.J. (2015). Liver glycogen reduces food intake and attenuates obesity in a high-fat diet-fed mouse model. Diabetes. 64(3): 796-807.

  19. Luo, L., Guo, Y., Chen, L., Zhu, J., Li, C. (2023). Crosstalk between cholesterol metabolism and psoriatic inflammation. Front Immunol. 14: 1124786. doi: 10.3389/fimmu.2023.1124786.

  20. Miller, J.P. (2000). Serum triglycerides, the liver and the pancreas. Curr Opin Lipidol. 11(4): 377-382.

  21. Musso, G., Gambino, R., Cassader, M. (2013). Cholesterol metabolism and the pathogenesis of non-alcoholic steatohepatitis. Prog Lipid Res. 52(1): 175-191.

  22. Nanashima, N., Horie, K., Yamanouchi, K., Tomisawa, T., Kitajima, M., Oey, I., Maeda, H. (2020). Blackcurrant (Ribes nigrum) extract prevents dyslipidemia and hepatic steatosis in ovariectomized rats. Nutrients. 12(5): 1541. doi: 10.3390/ nu12051541.

  23. Pan, J., Cen, L., Zhou, T., Yu, M., Chen, X., Jiang, W., Li, Y., Yu, C., Shen, Z. (2021). Insulin-like growth factor binding protein 1 ameliorates lipid accumulation and inflammation in nonalcoholic fatty liver disease. J. Gastroenterol Hepatol. 36(12): 3438-3447.

  24. Ruggiero, R.J., Likis, F.E. (2002). Estrogen: Physiology, pharmacology and formulations for replacement therapy. J. Midwifery Womens Health. 47(3): 130-138.

  25. Song, D., Yin, L., Wang, C., Wen, X. (2019). Adenovirus-mediated expression of SIK1 improves hepatic glucose and lipid metabolism in type 2 diabetes mellitus rats. PLoS One. 14(6): e0210930. doi: 10.1371/journal.pone.0210930.

  26. Stubbins, R.E., Najjar, K., Holcomb, V.B., Hong, J., Núñez, N.P. (2012). Oestrogen alters adipocyte biology and protects female mice from adipocyte inflammation and insulin resistance. Diabetes Obes Metab. 14(1): 58-66.

  27. Sun, C., Huang, F., Liu, X., Xiao, X., Yang, M., Hu, G., Liu, H., Liao, L. (2015). MiR-21 regulates triglyceride and cholesterol metabolism in non-alcoholic fatty liver disease by targeting HMGCR. Int J. Mol. Med. 35(3): 847-853.

  28. Wang, C., Song, D., Fu, J., Wen, X. (2020). SIK1 regulates CRTC2- mediated gluconeogenesis signaling pathway in human and mouse liver cells. Front Endocrinol (Lausanne). 11: 580. doi: 10.3389/fendo.2020.00580.

  29. Xi, J., Zheng, W., Chen, M., Zou, Q., Tang, C., Zhou, X. (2022). Genetically engineered pigs for xenotransplantation: Hopes and challenges. Front Cell Dev. Biol. 10: 1093534. doi: 10.3389/fcell.2022.1093534.

  30. Ye, Q., Liu, Y., Zhang, G., Deng, H., Wang, X., Tuo, L., Chen, C., Pan, X., Wu, K., Fan, J., Pan, Q., Wang, K., Huang, A., Tang, N. (2023). Deficiency of gluconeogenic enzyme PCK1 promotes metabolic-associated fatty liver disease through PI3K/AKT/PDGF axis activation in male mice. Nat Commun. 14(1): 1402. doi: 10.1038/s41467-023- 37142-3.

  31. Yuan, F., Wang, H., Tian, Y., Li, Q., He, L., Li, N., Liu, Z. (2016). Fish oil alleviated high-fat diet-induced non-alcoholic fatty liver disease via regulating hepatic lipids metabolism and metaflammation: a transcriptomic study. Lipids Health Dis. 15: 20. doi: 10.1186/s12944-016-0190-y.

  32. Zhang, Y., Takemori, H., Wang, C., Fu, J., Xu, M., Xiong, L., Li, N., Wen, X. (2017). Role of salt inducible kinase 1 in high glucose-induced lipid accumulation in HepG2 cells and metformin intervention. Life Sci. 173: 107-115.

  33. Zhu, J., Zhang, L., Ji, M., Jin, B., Shu, J. (2023). Elevated adipose differentiation-related protein level in ovariectomized mice correlates with tissue-specific regulation of estrogen. J. Obstet. Gynaecol. Res. 49(4): 1173-1179.
Reviewed By

Download Article
In this Article
    Contact us
    Follow us

    Editorial Board

    View all (0)