Different postnatal ontogeny of two [3H]neurotensin binding sites in rat brain

Two distinct neurotensin binding sites have been identified in rat brain: the NT1-acceptor site (levocabastine-sensitive) and the NT2-receptor site. In rat forebrain, NT2-receptors were present at birth, revealed a maximal level (13.8 fmol/mg tissue) on day 10 of postnatal life but a much lower plateau (3.0 fmol/mg tissue) in adult rats. NT1-acceptors were not detected before day 10 and became maximal at day 30. It is suggested that the loss of NT2-receptor sites during the postnatal development may be the expression of the regression of a transient redundancy of neuronal connections.