The Human Skeletal Muscle Transcriptome in Response to Oral Shilajit Supplementation

Abstract

The objective of the present study ( clinicaltrials.gov NCT02026414) was to observe the effects of oral supplementation of a purified and standardized Shilajit extract on skeletal muscle adaptation in adult overweight/class I obese human subjects from the U.S.

Population: Shilajit is a mineral pitch that oozes out of Himalayan rocks. The study design consisted of a baseline visit, followed by 8 weeks of 250 mg of oral Shilajit supplementation b.i.d., and additional 4 weeks of supplementation with exercise. At each visit, blood samples and muscle biopsies were collected for further analysis. Supplementation was well tolerated without any changes in blood glucose levels and lipid profile after 8 weeks of oral supplementation and the additional 4 weeks of oral supplementation with exercise. In addition, no changes were noted in creatine kinase and serum myoglobin levels after 8 weeks of oral supplementation and the additional 4 weeks of supplementation with exercise. Microarray analysis identified a cluster of 17 extracellular matrix (ECM)-related probe sets that were significantly upregulated in muscles following 8 weeks of oral supplementation compared with the expression at the baseline visit. This cluster included tenascin XB, decorin, myoferlin, collagen, elastin, fibrillin 1, and fibronectin 1. The differential expression of these genes was confirmed using quantitative real-time polymerase chain reaction (RT-PCR). The study provided maiden evidence that oral Shilajit supplementation in adult overweight/class I obese human subjects promoted skeletal muscle adaptation through upregulation of ECM-related genes that control muscle mechanotransduction properties, elasticity, repair, and regeneration.

Keywords: Shilajit; adaptation; extracellular matrix; skeletal muscle.

FIG. 1.

Heat map illustrating cluster of transcripts that were sensitive to PVS supplementation. PVS-sensitive transcripts were subjected to hierarchical clustering. (A) A total of 175 annotated probe sets were differentially (P < .05) regulated following 8 weeks of oral PVS supplementation compared with baseline visits. (B) Pathway analysis revealed an ECM-related cluster of probe sets that was significantly upregulated following 8 weeks of supplementation compared with corresponding baseline visit. COL1A1, collagen type I alpha1; COL1A2, collagen type I alpha 2; COL5A2, collagen type V alpha 2; COL6A3, collagen type VI alpha 3; COL14A1, collagen type XIV alpha 1, DCN, decorin; ECM, extracellular matrix; ELN, elastin; FBN1, fibrillin 1; FN1, fibronectin 1; MYOF, myoferlin; TNXB, tenascin XB; V1, baseline visit; V2, 8 weeks of oral PVS supplementation.

FIG. 2.

RT-PCR validation of ECM-related genes derived from microarray analysis following oral PVS supplementation. Expression levels of selected collagen genes identified using GeneChip^® analyses were independently verified using real-time quantitative (Q) PCR. The effects of oral PVS supplementation (250 mg/b.i.d.) were measured during the course of all visits; V1, baseline; V2, after 8 weeks of oral supplementation; V3a, additional (following 8 weeks of initial supplementation) 4 weeks of oral supplementation and exercise, sample collection before the final stint of exercise; and V3b, same as study visit 3, sample collected 30 min post-final bout of exercise. Data are mean ± SEM (n = 16); *P < .05 compared with the baseline visit and ^†P < .05 compared with 8 weeks. No significant changes were observed between pre and post 30-min final exercise on week 12. PCR, polymerase chain reaction.