Localisation of mRNA encoding the protein precursor of galanin in the monkey hypothalamus and basal forebrain.

Abstract

The hypothalamic and basal forebrain sites of synthesis of preprogalanin mRNA were identified in three adult monkeys (Macaca fascicularis) by in situ hybridisation performed with a radiolabelled cRNA probe transcribed from human preprogalanin cDNA. With stringent hybridisation conditions, the cRNA probe was hybridised to free-floating sections containing structures contiguous with the rostral hypothalamus through to the caudal limit of the hypothalamus as defined by the mammillary bodies. Specific hybridisation of the preprogalanin cRNA probe occurred throughout the hypothalamus but was particularly intense in the arcuate, paraventricular (parvicellular and magnocellular portions), and dorsomedial nuclei. Moderate hybridisation was found in the periventricular nucleus and scattered hybridisation in the medial preoptic nucleus. The medial preoptic area and the anterior and lateral hypothalamic areas showed moderate to intense hybridisation in scattered cells. A few cells in the tuberal portion and dorsal cap of the anterior portion of the supraoptic nucleus were labelled. Isolated cells were also labelled in the zona incerta. There was little labelling in the dorsal hypothalamic area but moderate labelling in the posterior hypothalamic area. Structures contiguous with the rostral hypothalamus including the diagonal band of Broca, bed nucleus of stria terminalis, substantia innominata, and basal nucleus of Meynert showed intense hybridisation. These data indicate a widespread distribution of preprogalanin mRNA in the monkey hypothalamus. A comparison with the previously reported distribution of preprogalanin mRNA in the rat, as well as with the distribution of galanin-like immunoreactivity in the rat and human, suggests some important species differences. Of particular interest were differences in the supraoptic, suprachiasmatic, and dorsomedial nuclei. The intense hybridisation throughout the paraventricular nucleus and in the rostral arcuate nucleus suggests that galanin may play a role in the regulation of both posterior and anterior pituitary function.