IN-SITU HYBRIDIZATION ANALYSIS OF THE DISTRIBUTION OF NEUROKININ-3 MESSENGER-RNA IN THE RAT CENTRAL-NERVOUS-SYSTEM

The tachykinin family of neuropeptides, which includes substance P, ne urokinin A, and neurokinin B, have three distinct receptors; NK-1, NK- 2, and NK-3. With the cloning of the rat NK-3 cDNA, it is now possible to evaluate the distribution of NK-3 mRNA in the rat brain. Female ra t brains were sectioned and hybridized with a riboprobe complimentary to NK-3 mRNA. The results of these studies revealed an extensive distr ibution of NK-3 mRNA throughout the rostral-caudal extent of the brain , spinal cord, and retina. In agreement with previous binding studies, we observed NK-3 mRNA in the cortex, the amygdala, the hippocampus, t he medial habenula, the zona incerta, the paraventricular and supraopt ic nuclei of the hypothalamus, the substantia nigra, the ventral tegme ntal area, the interpeduncular nucleus, the raphe nuclei, the dorsal t egmental nucleus, and the nucleus of the solitary tract. In contrast w ith binding data, only a few NK-3 mRNA cells were detected in the stri atum. In addition, the present study detected NK-3 mRNA in the olfacto ry bulb, the dentate gyrus and subiculum, the medial septum, the diago nal band of Broca, the ventral pallidum, the globus pallidus, the bed nucleus of the stria terminalis, the arcuate, the premammillary and ma mmillary nuclei, the dorsal and lateral regions of the posterior hypot halamus, the central gray, the cerebellum, the parabrachial nuclei, th e nucleus of the spinal trigeminal tract, the dorsal horn of the spina l cord, and the retina. The results of these in situ hybridization his tochemical studies have provided detailed and novel information about the distribution of NK-3 mRNA and have elucidated the putative sites o f neurokinin B action in the rat central nervous system. (C) 1996 Wile y-Liss, Inc.