Enzymic inactivation of neurotensin by hypothalamic and brain extracts of the rat.

A sensitive and specific radioimmunoassay has been developed to study inactivation of neurotensin by hypothalamic and brain peptidases. Degrading activity of peptidases from both hypothalamus and brain seems to have similar activity. These peptidases are temperature- and time- dependent. Brain and hypothalamic enzymes of particulate fractions can be differentiated on the basis of the pH effects; brain peptidase(s) has (have) maximal activity at pH 7.4 and hypothalamic peptidase(s) displaying a maximal activity at pH 5.8. Kidneys and liver extracts contain enzyme(s) degrading neurotensin.