Hippophae leaf extract (SBL-1) countered radiation induced dysbiosis in jejunum of total body ⁶⁰Cobalt gamma - irradiated mice

Single dose of SBL-1 administered at the rate 30 mg/kg body weight (b.w.) 30 min prior to whole body ⁶⁰Co-gamma-irradiation at lethal dose (10 Gy), rendered >90% survival in comparison to zero survival in the non-SBL-1 treated ⁶⁰Co-gamma-irradiated (10 Gy) mice population (J Herbs Spices Med Plants, 2009; 15(2): 203-215). Present study investigated the effect of SBL-1 on jejunal microbiota in lethally irradiated mice. Study was performed with inbred Swiss albino Strain 'A' male mice (age 9 weeks) weighing 28±2 g. The animals were maintained under controlled environment at 26±2℃; 12 h light/dark cycle and offered standard animal food (Golden feed, Delhi) as well as tap water ad libitum. Metagenomic DNA was extracted, purified and quantified from jejunum of the mice. Universal primers (27f and 1492r) were used to amplify the 16S rRNA DNA from the metagenomic DNA. Amplicons were sequenced, vector contamination and chimeras were removed. The sequences (GenBank Accession No: KF681283 to KF681351) were taxonomically classified by using Sequence Match program, Ribosomal Database Project as well as by nucleotide-BLAST (E-value: 10, database: 16S rRNA gene sequences, Bacteria and Archea). Phylogenetic Tree was prepared using MEGA 5.2 package, using maximum likelihood algorithm after sequence alignment by MUSCLE. Thermus aquaticus was used as out-group to construct rooted tree. Branch stability was assessed by bootstrap analysis. Untreated animals and the animals treated with SBL-1 had 100% Lactobacillus; ⁶⁰Co gamma-irradiated animals had 55% Cohaesibacter (Alphaproteobacteria); 27% Mycoplasma (Tenericutes) and only 18% Lactobacillus; animals treated with SBL-1 prior to irradiation had 89% Lactobacillus and 11% Clostridium. This study demonstrated that treatment with SBL-1 at radioprotective doses before total body irradiation with lethal dose (10 Gy) countered the jejunal dysbiosis. (author)