Effect of protein malnutrition on the composition of submandibular glands of aged rats.

Fifty 22-month-old male Sprague-Dawley rats were fed for 8 weeks ad libitum with either a 20% protein diet (control) or a 5% protein diet (protein malnourished group). Submandibular glands were removed, weighed and homogenate prepared. After the low protein diet, there was a slight but significant decrease in body weight, glandular content of total protein (mg/g tissue), kallikrein activity/mg protein and glutamine-rich peptide. In contrast, the gland weight, DNA and mucin content were not changed by feeding a low protein diet. Thus in aged rats submandibular glands are only modestly affected by protein malnutrition and the effects on gland-specific proteins vary.