Ontogeny of brain neurotensin in the rat: a radioimmunoassay study

Concentrations of neurotensin-like immunoreactivity in several discrete brain areas were measured by radioimmunoassay in rats of different ages (2, 5, 10, 20, 30, and 60 days). Neurotensin-like immunoreactivity increased steadily from 2 to 30 days of age in the hypothalamus and then plateaued, while the preoptic area and amygdala concentrations peaked at 30 days of age. Brainstem neurotensin-like immunoreactivity concentrations increased from 2 to 10 days of age and decreased from 20 to 60 days of age. Several other regions showed no significant age-associated changes in neurotensin-like immunoreactivity.