Effect of prior sensitization of stereotypy on the development of tolerance to amphetamine induced hypophagia

It was hypothesized that animals sensitized to the stereotyped behavioral effects of amphetamine would have a more difficult time developing tolerance to the hypophagic effect of the drug than nonsensitized animals. Although sensitized animals showed more intense stereotypy, they were not impaired in the development of tolerance, or in the amount of tolerance gained, thus showing a dissociation between these two variables. Differential sensitization was also shown to these effects. That is, sensitized animals were not impaired on milk intake, whereas nonsensitized animals became more sensitive to the hypophagic effect of amphetamine. Further, it was found that animals sensitized to the stereotyped behavioral effects of the drug developed tolerance to this effect, and this tolerance was found to occur both in the presence and absence of milk.