Hypothalamo-posterior pituitary system in Brattleboro rats: immunoreactive levels of leucine-enkephalin, dynorphin (1-17), dynorphin (1-8) and alpha-neo-endorphin

The levels of immunoreactive leucine-enkephalin, alpha-neo-endorphin, dynorphin (1-17) and dynorphin (1-8) have been determined in the hypothalamus and posterior pituitary from male and female Brattleboro rats homozygous (unable to produce vasopressin) and heterozygous (producing vasopressin) for diabetes insipidus, and from male and female Long Evans rats. In the hypothalamus we found no significant differences in the levels of these peptides while there were great differences in extracts from the posterior pituitary: female homozygous animals have greatly reduced levels in all four peptides compared to the heterozygous controls. In male homozygous animals the differences in the dynorphin (1-17) and leucine-enkephalin levels were small whereas the concentrations of alpha-neo-endorphin and dynorphin (1-8) showed a significant decrease compared to the male heterozygous controls. The results indicate a reduction in opioid peptides linked to the vasopressin deficiency in a partially sex dependent manner.