Determination of the protective effects of boric acid against experimentally induced cholestasis with ANIT in rats
Tissue and Cell, cilt.104, 2027 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 104
- Basım Tarihi: 2027
- Doi Numarası: 10.1016/j.tice.2026.104065
- Dergi Adı: Tissue and Cell
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, EMBASE, MEDLINE, Zoological Record
- Anahtar Kelimeler: ANIT, Boric acid, BSEP, Cholestasis, Liver
- Uşak Üniversitesi Adresli: Evet
Özet
Cholestasis is self-perpetuating: failure of canalicular bile salt export expands the intracellular bile acid pool, and retained acids progressively disrupt the systems and barriers sustaining bile secretion. α-Naphthylisothiocyanate (ANIT) is widely used to model intrahepatic cholestasis. Boron, internalized through the NaBC1 (SLC4A11) transporter, regulates redox balance and membrane integrity; however, its protective mechanisms in the cholestatic liver remain undefined. The explicit mechanism tested was that boric acid interrupts this circuit at its regulatory origin: by sustaining sirtuin-1 (SIRT1), which deacetylates the farnesoid X receptor (FXR) at Lys-217 and thereby maintains transcription of its canalicular targets — the bile salt export pump (BSEP), UDP-glucuronosyltransferase 1A1 (UGT1A1) and cholesterol 7α-hydroxylase (CYP7A1) — while phosphoinositide 3-kinase/protein kinase B (PI3K/AKT)-dependent preservation of the claudin-1/occludin/zonula occludens-1 (ZO-1) barrier and restraint of the protein kinase R-like endoplasmic reticulum kinase (PERK)–eukaryotic initiation factor 2α (eIF2α)–activating transcription factor 4 (ATF4)–C/EBP homologous protein (CHOP) arm of the unfolded protein response (UPR) limit the downstream consequences. Forty male Sprague Dawley rats received vehicle, ANIT (50 mg/kg, intragastrically), boric acid (100 mg/kg/day, 7 days) before ANIT, or boric acid alone, and were sacrificed 24 h later. Transporters and the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1)/SIRT1 axis were analyzed by Western blot; the unfolded protein response and PI3K/p-AKT/mTOR signaling by immunohistochemistry; tight junction proteins and 8-hydroxy-2′-deoxyguanosine (8-OHdG) by immunofluorescence; and FXR, CYP7A1, and UGT1A1 by RT-qPCR, alongside histopathology. ANIT markedly suppressed BSEP and Na⁺/taurocholate cotransporting polypeptide (NTCP) while preserving multidrug resistance-associated protein (MRP)2, which exports the ANIT–glutathione conjugate, indicating selective impairment of bile salt-dependent secretion rather than canalicular export. FXR exhibited the greatest proportional reduction, with coordinated declines in CYP7A1 and UGT1A1, identifying the SIRT1–FXR node rather than any individual carrier as the level of regulatory failure. These alterations coincided with more than tenfold induction of glucose-regulated protein 78 (GRP78), eIF2α, ATF4, and CHOP, disruption of occludin, claudin-1 and ZO-1, 8-OHdG accumulation, suppression of Nrf2/HO-1 and PI3K/p-AKT/mechanistic target of rapamycin (mTOR) signaling and a tenfold expansion of fibrotic area. Boric acid attenuated these changes differentially: transporters, junctional integrity, redox balance and tissue architecture approached control levels, whereas the unfolded protein response and transcriptional bile acid regulation recovered only partially. Because NaBC1, SIRT1 and PI3K/AKT were not inhibited, this sequence is inferred from coordinated, pathway-consistent expression changes rather than established causally.