Ekspresi mRNA SOD1, SOD2, p16 Pada Ginjal Tikus Model Obesitas Induksi Diet Tinggi Lemak

NUR RAHMAWATI S, dr. Nungki Anggorowati, Sp.PA(K), Ph.D; dr. Widya Wasityastuti, M.Sc, M.Med.Ed, Ph.D; dr. Nur Arfian, Ph.D

2022 | Tesis | MAGISTER ILMU BIOMEDIK

Latar Belakang: Obesitas telah menjadi epidemi global dengan prevalensi yang meningkat di Indonesia, dan dapat menginduksi berbagai penyakit termasuk penyakit ginjal. Pada kondisi obesitas, free fatty acid (FFA) yang beredar cenderung tinggi dan melebihi kapasitas jaringan lemak menampung asam lemak, sehingga menyebabkan akumulasi lipid ektopik di berbagai organ termasuk ginjal. Lemak yang terakumulasi dalam ginjal menyebabkan peningkatan reactive oxygen species (ROS) yang seharusnya dapat disrespon dan diatasi pada tahap awal oleh enzim superoksida dismutase (SOD). Stress oksidatif terjadi ketika ROS tidak diimbangi oleh antioksidan dan akan mengindukasi senescence. Sel yang mengalami senescence akan menghasilkan senescence associated secretory phenotype (SASP) yang menyebabkan kerusakan pada organ yang dekat maupun kerusakan yang bersifat sistemik. Tujuan: Penelitian ini bertujuan untuk mengetahui pengaruh diet tinggi lemak 1 bulan, 2 bulan dan 4 bulan terhadap ekspresi gen-gen penanda antioksidan (SOD1 dan SOD2) serta senescence (p16) pada ginjal dan jaringan lemak retroperitoneal tikus model obesitas. Metode: Induksi obesitas dengan diet tinggi lemak selama 1 bulan, 2 bulan dan 4 bulan sebagai kelompok perlakuan. Komposisi diet tinggi lemak kelompok perlakuan adalah 21.2% protein, 24% karbohidrat dan 54.8% lemak diberikan sebanyak 10% dari berat badan tikus. Indeks Lee diukur pada kelompok control maupun kelompok perlakuan. Reverse Transcription-PCR (RT-PCR) dilakukan untuk mengetahui ekspresi gen SOD1 ginjal, SOD2 ginjal, p16 ginjal dan p16 jaringan lemak. Hasil: Hasil pegukuran indeks Lee menujukkan peningkatan signifikan pada kelompok perlakuan dibanding kontrol. Ekspresi mRNA p16 jaringan lemak mengalami peningkatan signifikan pada diet tinggi lemak 2 bulan dan 4 bulan dibanding kontrol. Ekspresi mRNA SOD1 ginjal mengalami penurunan signifikan pada kelompok diet tinggi lemak 4 bulan. Ekspresi mRNA SOD2 tidak berbeda antara kelompok kontrol dan perlakuan. Ekspresi mRNA p16 ginjal mengalami peningkatan signifikan pada kelompok perlakuan dibandingkan dengan kelompok kontrol. Kesimpulan: Diet tinggi lemak selama 1 bulan dapat meningkatkan indeks Lee dan mRNA p16 ginjal secara signifikan dibanding kontrol. Diet tinggi lemak selama 2 bulan dapat meningkatkan indeks Lee, mRNA p16 ginjal dan jaringan lemak dibanding kontrol. Diet tinggi lemak 4 bulan dapat meningkatkan indeks Lee, mRNA p16 jaringan lemak, mRNA SOD1 dan mRNA p16 ginjal. mRNA SOD2 tidak berbeda antara kelompok kontrol dengan kelompok perlakuan.

Background: Obesity has become a global epidemic with increasing prevalence in Indonesia, and can induce various diseases including kidney disease. Under conditions of obesity, circulating free fatty acids (FFA) tend to be high and exceed the capacity of fat tissue to accommodate fatty acids, causing ectopic lipid accumulation in various organs including the kidneys. Fat that accumulates in the kidneys causes an increase in reactive oxygen species (ROS) which should be able to be responded to and overcome at an early stage by the enzyme superoxide dismutase (SOD). Oxidative stress occurs when ROS are not balanced by antioxidants and will induce senescence. Cells that experience senescence will produce a senescence associated secretory phenotype (SASP) that causes damage to nearby organs and systemic damage. Aim: This study aims to determine the effect of a high-fat diet 1 month, 2 months and 4 months on the expression of antioxidant marker genes (SOD1 and SOD2) and senescence (p16) in the kidneys and retroperitoneal fat tissue of obese rats. Method: High fat diet obesity induction for 1 month, 2 months and 4 months was conducted as the treatment groups with one control group. The composition of the high-fat diet in the treatment group was 21.2% protein, 24% carbohydrate and 54.8% fat given as much as 10% of the rat's body weight. Lee's index was measured in both the control group and the treatment group. Reverse Transcription-PCR (RT-PCR) was performed to determine the gene expression of kidney SOD1, kidney SOD2, kidney p16 and p16 adipose tissue. Result: The results of the Lee index measurement showed a significant increase in the treatment group compared to the control group. The p16 mRNA expression of fat tissue was significantly increased in the high-fat diet 2 months and 4 months compared to the control. Renal SOD1 mRNA expression was significantly decreased in the 4-month high-fat diet group. SOD2 mRNA expression did not differ between the control and treatment groups. Renal p16 mRNA expression had a significant increase in the treatment group compared to the control group. Conclusion: High-fat diet for 1 month can significantly increase the Lee index and kidney p16 mRNA compared to controls. High-fat diet for 2 months can increase Lee index, kidney p16 mRNA and fat tissue compared to controls. High-fat diet 4 months can increase Lee index, mRNA p16 fat tissue, mRNA SOD1 and mRNA p16 kidney. Theres no difference between SOD2 mRNA of the control group and the treatment group.

Kata Kunci : Diet tinggi lemak, SOD1, SOD2, p16, ginjal, jaringan lemak, senescence, SASP