Galanin immunoreactivity in the primate central nervous system.

Galanin-immunoreactive profiles were localized within the monkey and human central nervous system. In the monkey telencephalon, galanin-immunoreactive perikarya were seen within the anterior olfactory nucleus, basal forebrain, endopiriform nucleus, hippocampus, and bed nucleus of the stria terminalis. The caudate nucleus and putamen contained galanin-immunoreactive perikarya whereas the nucleus accumbens displayed only galanin-immunoreactive fibers. In the diencephalon, galanin-immunoreactive profiles were seen within the medial preoptic area, periventricular, suprachiasmatic, paraventricular, and arcuate nuclei as well as the lateral hypothalamic area. Within the thalamus, only galanin-immunoreactive fibers were seen within the midline paraventricular, reuniens, and rhomboid nuclei. In the mesencephalon, scattered galanin-immunoreactive fibers were seen in the periaquaductal gray, ventral tegmental area, and midbrain reticular formation. In the metencephalon, galanin-immunoreactive neurons were observed in the medial vestibular nucleus and nucleus prepositus. In the myelencephalon, galanin-immunoreactive perikarya were seen within the nucleus of the tractus solitarius and hypoglossal nucleus. Dense collections of galanin-immunoreactive fibers were found in the spinal descending tract of V, nucleus of the tractus solitarius, and dorsal motor nucleus of X. Galanin immunoreactivity was also observed within all circumventricular organs. Spinal anterior horn neurons expressed galanin immunoreactivity, and immunopositive fibers were seen within the tract of Lissauer and the substantia gelatinosa. Although the distribution of galanin immunoreactivity was generally similar between monkeys and humans, there were a few striking exceptions. The human supraoptic nucleus contained galanin-immunoreactive neurons, whereas the monkey supraoptic nucleus displayed only immunopositive fibers. Similarly, galanin-immunoreactive perikarya and fibers were seen in the human locus coeruleus and subcoeruleus, whereas in monkeys these regions contained only fibers. These data demonstrate a widespread distribution of galanin-containing profiles in primates, suggesting that galanin may modulate cognitive, sensory, motor, and autonomic processes.