[Effects of cortisol, malnutrition and orchiectomy on the concentrations of proteins and nucleic acids in rat muscle].

The cortisol action on some gastrocnemius muscle parameters, related to protein synthesis was studied in normal and orchidectomized male rats. Since cortisol causes an intake reduction, pair-feeding runs were conducted to achieve results of the hormone action unbiased by the effects derived from the intake restriction. Administration of cortisol in doses of 0.8 mg/100 g of body weight/day to rats from weaning up to 30 days produced a significant reduction in protein synthesis, DNA, RNA and cell number in the muscle. The intake restrictions provoked by cortisol, produced a significant reduction in protein content, cell weight, RNA, velocity of protein synthesis (RNA/proteins), protein synthesis/DNA (RNA/DNA) and produced muscle atrophy. With the exception of DNA/RNA and muscle cell number, all other parameters were reduced by the orchidectomy in control rats with normal intake, and significant differences were found in ad libitum fed and pair-fed rats. Cortisol treatment, the cortisol-provoked intake restriction and orchidectomy impaired muscle protein synthesis. Muscle protein content was reduced by intake restriction, and this effect was more pronounced by the cortisol activity, especially in orchidectomized rats, probably due to their lacking androgenic protection which would normally counteract the cathabolic action of cortisol.