Transient neurotensin in the human inferior olive during development.

A large number of transient neurotensin-immunoreactive nerve terminals are found in the human principal inferior olive of the medulla oblongata during the first year of age and almost completely disappear in the adult. Their neurotensin content is further characterized as neurotensin(1-13) using radioimmunoassay and gel filtration and reaches 582 pmol per gram wet weight at 6 months. Neurotensin nerve terminals are exclusively located in the principal olive and a dense bundle of neurotensin nerve fibers is also present in the central tegmental tract. Thus, these olivary neurotensin nerve terminals probably originate in mesencephalic neurons. In addition to its recognized role in neurotransmission or neuromodulation, neurotensin may thus also be implicated in the postnatal development of the human principal olive and indirectly in that of the neocerebellum.