Persistence of lateral hypothalamic-mediated behaviors after a supralethal dose of ionizing radiation.

After exposure to 10 krad of high-energy electrons, rats experience an early transient incapacitation characterized by symptoms similar to those associated with lateral hypothalamic lesions: akinesia and decrements in various motivated behaviors. Experimenter-imposed electrical stimulation of the lateral hypothalamus in akinetic, irradiated animals produced a locomotor response similar to that seen in unexposed rats. Furthermore, when allowed to self-stimulate, the irradiated subjects persisted in vigorous self-stimulation of the lateral hypothalamus while self-stimulation rates of other subcortical sites showed marked attenuation. The lateral hypothalamus is apparently less sensitive to ionizing radiation than are the other subcortical structures sampled.