Elective tolerance to behavioral effects of neurotensin.

Neurotensin reduces locomotor activity in an open field situation as well as responsiveness to electric footshock. Repeated injections of neurotensin in combination with repeated testing of locomotor activity in the open field as well as repeated injections of neurotensin without such testing in the open field do not result in a reduction of locomotor activity. These findings make development of tolerance to this behavioral effect of neurotensin likely. Such a development of tolerance to neurotensin is not observed for the effect on responsiveness to electric footshock.