Effects of replacing soybean oil with coconut oil on autophagy-related markers in skeletal muscle and adipose tissue of rats fed normolipidic diets

Aims: To evaluate the effects of partial or complete replacement of soybean oil with coconut oil in normolipidic diets on autophagy-related molecular markers in skeletal muscle and adipose tissue of rats. Study Design: Experimental study using three dietary groups of male Wistar rats. Methodology: Rats were fed diets containing soybean oil (GC; 70 g/kg), a mixture of soybean and coconut oils (GM; 35 g/kg each), or coconut oil (GOC; 70 g/kg) for 60 days. Gastrocnemius muscle and epididymal adipose tissue were collected to determine the mRNA expression of Sqstm1, Atg7, and Map1lc3 by quantitative real-time PCR and the protein abundance of p62 and Beclin-1 by Western blotting. Data were analyzed using one-way ANOVA followed by Tukey's post hoc test. Results: In gastrocnemius muscle, Sqstm1 mRNA expression was significantly lower in GOC than in GC (P < .04), whereas GM did not differ significantly from either group. No significant differences were observed in Atg7 or Map1lc3 mRNA expression among groups. In epididymal adipose tissue, the expression of all three genes remained similar across dietary groups. Furthermore, p62 and Beclin-1 protein abundance did not differ significantly among groups in either tissue. Cumulative food intake, body weight gain, and absolute and relative tissue weights were also similar among groups. Conclusion: Complete replacement of soybean oil with coconut oil in normolipidic diets reduced Sqstm1 mRNA expression in gastrocnemius muscle without corresponding changes in p62 protein abundance or other autophagy-related markers. The functional significance of this transcriptional response remains unclear, as autophagic flux was not evaluated.