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Hubungan Restriksi Vitamin B12 dengan Perubahan Struktur dan Fungsi Ginjal Ditinjau dari Jalur Enzim Metionin Sintase dan Metilmalonil-KoA Mutase pada Tikus Sprague-Dawley. = Vitamin B12 Restriction Effects on Structural And Functional Changes of Sprague-Dawley Rat Kidney via Methionine Synthase And Methylmalonyl-CoA Mutase Enzymes Pathway.

Pendahuluan. Defisiensi vitamin B12 masih merupakan masalah kesehatan di negara maju dan berkembang. Beberapa laporan kasus menunjukan adanya hubungan antara kelainan gen yang terlibat dalam proses absorbsi vitamin B12 dengan penyakit ginjal progresif kronis. Penelitian ini bertujuan menganalisis hubungan restriksi vitamin B12 dengan perubahan struktur dan fungsi ginjal. Metode. Penelitian ini merupakan studi eksperimental in vivo yang dilakukan di FK UI dan Laboratoriun Hewan Litbangkes Depkes dari Maret 2017 hingga Mei 2018. Tikus Sprague-Dawley sebanyak 18 ekor dibagi menjadi tiga kelompok: (1) kontrol yang diberi pakan standar hewan coba AIN- 93M selama 12 minggu; (2) perlakuan-1 (P-1) diberi pakan AIN-93M modifikasi tanpa vitamin B12 selama 4 minggu; dan (3) perlakuan-2 (P-2) yang diberi pakan AIN-93M modifikasi tanpa vitamin B12 selama 12 minggu. Status vitamin B12 ditentukan dengan kadar vitamin B12 total, homosistein, dan asam metilmalonat plasma. Struktur histologis ginjal dinilai dengan pewarnaan Hematoxylin-Eosin dan Masson Trichrome. Fungsi ginjal ditentukan dengan mengukur kadar kreatinin serum, kreatinin urine, laju bersihan kreatinin, protein total urine, Kidney Injury Marker (KIM-1) dan tekanan darah. Hasil. Vitamin B12 plasma total turun dari 529.17±166.51 pg/ml menjadi 426.33 ± 60.59 pg/ml pada P-1 dan 708.70 ± 124.35 pg/ml menjadi 519.16 ± 84.96 pg/ml pada P-2, sedangkan pada kelompok kontrol meningkat dari 567.79 ± 102.52 pg/ml menjadi 650.26 ± 193.12 pg/ml. Homosistein plasma meningkat pada kelompok perlakuan setelah 4 minggu (kontrol vs P-1 = 351.05 ± 110.69 pmol/ml vs 597.09 ± 308.02 pmol/ml) dan 12 minggu (kontrol vs P-2 = 414.473 ± 224.13 pmol/ml vs 1055.12±651.68 pmol/ml, p < 0.05). Laju bersihan kreatinin turun pada kelompok perlakuan setelah 4 minggu (kontrol vs P-1 = 1.56 ± 1.18 ml/min/kgBB vs 0.95 ± 0.70 ml/min/kgBB) dan 12 minggu (kontrol vs P-1 = 1.67 ± 0.29 ml/min/kgBB vs 0.93 ± 0.21 ml/min/kgBB). KIM-1 urine meningkat pada kelompok P-1 (kontrol vs P-1 = 129.15 ± 47.85 pg/ml vs 164.85 ± 46.33 pg/ml) dan P-2 (kontrol vs P-2 = 157.87 ± 45.41 pg/ml vs 339.25 ± 104.18 pg/ml, p < 0.05). Gambaran histologis ginjal tampak gambaran tubulointerstisial nefritis, tubular atropi serta proses fibrosis. Kesimpulan. Restriksi diet vitamin B12 pada tikus berhubungan dengan penurunan fungsi ginjal yang disertai perubahan struktur histologis berupa kerusakan tubulus, sebukan sel radang dan proses fibrosis.
Kata Kunci: Vitamin B12, Homosistein, Ginjal.


Introduction.Vitamin B12 deficiency is still a health problem in both developed and developing countries. Several case reports showed an association between MMACHC gene abnormality and renal impairment. MMAHC is a gene responsible for cellular absorption of vitamin B12. This study was conducted to explore possible relationship between vitamin B12 dietary restriction with kidney’s histological and physiological changes. Methods. This was an in vivo experimental study conducted at Faculty of Medicine, UI and Animal Laboratory of Ministry of Health RI from March 2017-May 2018. Eighteen male Sprague Dawley rats were divided into three groups: (1) control group were fed with standard AIN-93M for 12 weeks; (2) 1st treatment group (P-1) were fed with cobalamin restricted AIN-93M for 4 weeks; and (3) 2nd treatment group (P-2) were fed with cobalamin restricted AIN-93M for 12 weeks. Vitamin B12 status was obtained by determining the level of plasma total vitamin B12 (VB12), homocysteine (Hcy) and methylmalonic acid plasma (MMA). Kidney histological structure was observed with Hematoxylin-Eosin and Masson Trichrome staining. Serum and urine creatinine, creatinine clearance, total urinary protein, Kidney Injury marker (KIM-1) and blood pressure were measured at 0, 4, and 12 weeks. Result.Vitamin B12 level decreased from 529.17±166.51 pg/ml to 426.33±60.59 pg/ml in P-1 group and from 708.70±124.35 pg/ml to 519.16±84.96 pg/ml in P-2 group, while it increased from 567.79±102.52 pg/ml to 650.26±193.12 pg/ml in control group after 12 weeks. Plasma Hcy increased in treatment group after 4 weeks (control vs P-1 = 351.05±110.69 pmol/ml vs 597.09±308.02 pmol/ml) and 12 weeks (control vs P-2 = 414.473±224.13 pmol/ml vs 1055.12±651.68 pmol/ml; p < 0.05). Creatinine clearance decreased in treatment group after 4 weeks (control vs P-1 = 1.56±1.18 ml/min/kgBW vs 0.95±0.70 ml/min/kgBW) and 12 weeks (control vs P-1 = 1.67±0.29 ml/min/kgBW vs 0.93±0.21 ml/min/kgBW). KIM-1 increased in P-1 group (control vs P-1 = 129.15±47.85 pg/ml vs 164.85±46.33 pg/ml) and P-2 group (control vs P-2 = 157.87±45.41 pg/ml vs 339.25±104.18 pg/ml; p < 0.05). Histological findings were tubulointerstitial nephritis appeareance, with tubular atrophy and fibrotic process in treatment group. Conclusion. Dietary restriction of vitamin B12 in rat model was associated with decreased of renal function accompanied with renal tubular damage, fibrosis and inflammatory cell infiltration.
Keyword: Vitamin B12, Homocysteine, Kidney.