Distribution of noradrenaline in the brain of the teleost Gasterosteus aculeatus L.: an immunohistochemical analysis.

The distribution of noradrenergic neurons in the brain of the three-spined stickleback was demonstrated with the indirect peroxidase-antiperoxidase (PAP) immunohistochemical method with antibodies against a noradrenaline-bovine serum albumin conjugate. Noradrenergic neuronal somata were exclusively located in the isthmal area of the brain stem and in the lower medulla. Noradrenergic varicose axons innervate the reticular formation, motor nuclei, and interpeduncular nucleus of the brain stem, the hypothalamus and habenular nuclei, various parts of the area dorsalis telencephali (forebrain pallium), and the olfactory bulbs. Scattered noradrenergic axons were observed in the optic tectum and in various parts of the cerebellum. It is concluded that the isthmal cell group of the stickleback is, on topological and cytoarchitectonic grounds, equivalent to the ventral portion of the locus coeruleus/subcoeruleus area of amniotes, but that its efferent connections display features characteristic both of those originating in the locus coeruleus, and in the lateral tegmental cell groups of mammals.