Cells of origin of the descending afferents to the lateral hypothalamic area in the rat, studied with the horseradish peroxidase method.

Cells of origin of the descending afferents to the lateral hypothalamic area (LHA) were examined following iontophoretic injections of horseradish peroxidase (HRP). HRP-positive neurons were found ipsilaterally and mainly in the following structures: the infralimbic cortex (area 25), septal area including the nucleus of the diagonal band, nucleus accumbens, olfactory tubercle, medial and lateral preoptic areas, preoptic magnocellular nucleus, substantia innominata, bed nucleus of the stria terminalis and the central amygdaloid nucleus. Of these, neurons of the nucleus accumbens, olfactory tubercle, preoptic magnocellular nucleus and substantia innominata were preferentially labeled when the enzyme was deposited in the lateral part of the LHA.