LOCALIZATION OF NEURONS EXPRESSING SUBSTANCE-P AND NEUROKININ-B GENE TRANSCRIPTS IN THE HUMAN HYPOTHALAMUS AND BASAL FOREBRAIN

In situ hybridization histochemistry was used to map the distribution of neurons expressing the substance P (SP) or neurokinin B (NKB) genes in the human hypothalamus and basal forebrain. Hypothalami from five adult males were frozen in isopentane at -30 degrees C and serially se ctioned at 20 mu m thickness. Every 20th section was hybridized with [ S-35]-labeled, 48-base synthetic cDNA probes that were complementary t o either SP or NKB mRNAs. Slides were dipped into nuclear emulsion for visualization of mRNAs at the single-cell level. The location of labe led neurons (greater than x5 background) was mapped by using an image- combining computer microscope system. A distinct and complementary dis tribution pattern of SP and NKB neurons was observed in the human hypo thalamus and basal forebrain. NKB was the predominant tachykinin in th e rostral hypothalamus, whereas SP mRNA predominated in the posterior hypothalamus. Numerous NKB neurons were identified in the magnocellula r basal forebrain, the bed nucleus of stria terminalis, and the anteri or hypothalamic area. Scattered NKB neurons were present in the infund ibular and paraventricular nuclei, paraolfactory gyrus, posterior hypo thalamic area, lateral division of the medial mammillary nucleus, and amygdala. Numerous neurons expressing SP mRNAs were identified in the premammillary, supramammillary, and medial mammillary nuclei; the post erior hypothalamic area; and the corpus striatum. Scattered SP neurons were also observed in the preoptic area; the infundibular, intermedia te, dorsomedial, and ventromedial nuclei; the infundibular stalk; the amygdala; the bed nucleus of stria terminalis; and the paraolfactory g yrus. These studies provide the first description of the location of n eurons that express tachykinin gene transcripts in the human hypothala mus. (C) 1997 Wiley-Liss, Inc.