Undernutrition during suckling does not change the specific or total activity of hypothalamic proline endopeptidase in adult rats

Undernutrition during suckling causes a decrease in hypothalamic beta-endorphin-like immunoreactivity in rats. Since proline endopeptidase (E.C. 3.4.21.26) has been proposed to play a role in the processing of beta-endorphin, we examined the effects of undernutrition during suckling on the enzyme activity. Rats were undernourished by feeding their dams an 8% casein diet from the day of birth until weaning (21 days). Dams of well-nourished rats were fed a 25% casein diet during the same period. After weaning, all rats received a 20% protein diet until 90 to 120 days of age when they were killed for the enzyme assay. The specific and total activity of hypothalamic proline endopeptidase was not altered by undernutrition followed by nutritional rehabilitation (2.37 +/- 0.24 nmol sulphamethoxazole min-1 mg-1 for well-nourished rats vs 2.68 +/- 0.24 nmol sulphamethoxazole min-1 mg-1 for undernourished rats). This lack of correlation suggests that proline endopeptidase is probably not responsible for the low levels of hypothalamic beta-endorphin found in adult rats submitted to undernutrition during suckling.