Locomotor stepping initiated by glutamate injections into the hypothalamus of the anesthetized rat.

Glutamate (50 mM, 50 nl) injected into the tuberal and posterior hypothalamus was tested for capacity to elicit locomotor stepping. Rats (n = 23) were anesthetized with Nembutal and suspended by a sling in a stereotaxic apparatus such that locomotor stepping rotated a wheel. In 61 of 275 sites tested, stepping was initiated by glutamate injections within 60 s. Positive sites were widespread and contained in the lateral hypothalamus, the perifornical area, the dorsomedial nucleus, and the zona incerta. The perifornical and lateral hypothalamic sites were most likely to have locomotor responses and the shortest latencies. These findings indicate that selective activation of hypothalamic neurons as opposed to fibers of passage can initiate locomotion.