Muscle Protein in Growing Rats Fed Spirulina as the Sole Dietary Protein Source

Abstract

PURPOSE: The malnutrition condition, in the 21st century, still remains an important factor impairing human health and productivity, mainly in the developing countries. Therefore, the exploration of alternative alimentary protein sources became a matter of generalized interest. This study evaluates the effects of the blue green alga spirulina as the sole dietary source of protein on muscle protein of growing rats. METHODS: Young (30 days) Wistar rats were fed, during 60 days, with 17% protein spirulina (S) and compared to rats fed 17% protein casein (C). We evaluated the muscle total protein and DNA contents, the protein synthesis and degradation as well the myosin protein expression (western blotting analyses). RESULTS: The groups presented similar body weight (C= 427.3 ± 8.6; S= 434.6 ± 7.7g) and length (C= 25.4 ± 0.2; S= 25.6 ± 0.2cm). Soleus muscle total protein (C= 2.9 ± 0.1; S= 2.7 ± 0.1 mg/100mg) and DNA (C= 0.084 ± 0.005; S= 0.074 ± 0.005 mg/100mg) contents were also similar in both groups. Protein degradation rates (C= 427.5 ± 40.6; S= 476.7 ± 50.5 nmol/g.h) did not differ between the groups but protein synthesis rates (C= 17.5 ± 1.0; S= 25.2 ± 1.9 nmol/g.h) and myosin content were significantly higher (P<0.05; t test) in spirulina group. CONCLUSIONS: Although the spirulina proved adequate protein quality to maintain body growth, the muscle protein synthesis rates and myosin content were improved by the ingestion of the experimental diet in young rats. Further studies are required in order to clarify the real mechanisms involved in the effects of dietary spirulina protein source on muscle protein. Financial Support: CAPES (Brazilian Foundation)