Nils-Åke Hillarp

Demonstration and mapping out of nigro-neostriatal dopamine neurons

Abstract In normal rats dopamine-storing nerve terminals are found in the neostriatum (= the caudate nucleus + putamen) and dopamine-containing nerve cells in the substantia nigra, mainly in the pars compacta. After electrolytic lesions in the substantia nigra or the internal capsule the histochemical fluorescence and the dopamine content of the neostriatum were markedly reduced. Removal of the neostriatum produced an increased fluorescence of the dopamine nerve cells of the substantia nigra and of their axons central to the lesion. These axons ascend as a nerve tract in the internal capsule towards the neostriatum. The data give strong evidence for the existence of nigro-neostriatal dopamine neurons, which probably contain most or all of the dopamine present in the neostriatum.

CENTRAL MONOAMINE NEURONS

Publisher Summary This chapter discusses the chemistry, histochemistry, specificity, and sensitivity of central monoamine neurons. The first step in the fluorescence reaction in the case of catecholamines (CA) is a condensation, resulting in the formation of a 6,7-dihydroxy-l,2,3,4-tetrahydroisoquinoline. Under the mild conditions used, the great activation of the 3-OH group is required for this condensation to be achieved and the catecholamines must obviously be either primary or secondary amines. Their 3-0-methylated and acid metabolites therefore do not react. The next step is a quite unexpected protein-promoted dehydrogenation, which gives the final fluorescent product, a 6,7-dihydroxy-3,4-dihydroisoquinoline.In the case of a secondary amine, this dehydrogenation gives rise to a quaternary 3,4-dihydroisoquinoline and requires more severe reaction conditions. Primary and secondary catecholamines can, thus, be differentiated from each other histochemical in a simple manner. The fluorescent product, 6-hydroxy-3,4-dihydro-β-carboline, has an emission spectrum with a peak about 50 mμ higher than that of the fluorescent product formed from CA.

5-HYDROXYTRYPTAMINE RELEASE BY NERVE STIMULATION OF THE SPINAL CORD.

Abstract In mice and frogs the spinal cords were dissected out and suspended in Ringer solution. Electrical stimulation resulted in release and increased synthesis of 5-hydroxytryptamine.

Uptake of L-dopa and noradrenaline by central catecholamine neurons

Abstract Not only teh nerve terminals bu the entire peripherals adrenergic neuron can take up and accumulated noradrenaline (NA) by a specific mechanism localized to the cell membrane 1, 2, 3 . It is not known whether the central catechiolamine (CA) neurons also have this mechanism, since teh amine penetrates the blood-brain barrier to at most a minot extent 4 . In contrast to the peripheral adrenergic ganglion cells, which readily accumulated high amine concentrations following the administration of L-dopa 5 , the cell bodies of the central neurons usually show at the most a slight increase, even when high doses are given to animals pretreated with the potent monoamine oxidase inhinbitor nialamide 6 . The recent finding, however, that the two regions of the brain that lack the blood-brain barrier and take up labeled CA 7, 8 contain CA nerve cells or nerve terminals of the adrenergic type has made possible a more direct comparison. The median eminence has been found to have abundant terminals, which probably originate mainly from dopamine cells in the arcuate and adjacent nuclei 9, 10 . Numeous CA nerve cells exist, on the other hand, in the area postrema 11

Mast cells and monoamines

Mit einer Ausnahme scheinen alle Arten von Säugetieren, die mit vergleichbaren Methoden untersucht worden sind, lokale Gewebslager von Monoaminen zu haben in einem System von spezifischen Zellen, die zur grossen Gruppe der Gewebsmastzellen gehören. Diese Zellen scheinen die spezifischen Merkmale der monoaminbildenden Zellen zu besitzen. Biochemisch scheinen die Gewebsmastzellen an einer heterogenen Gruppe zu gehören, die aus wenigstens zwei ganz verschiedenen Zelltypen besteht.

Noradrenaline release by nerve stimulation of the spinal cord

Abstract In mice pretreated with the monoamine oxidase inhibitor nilamide the spinal cords were dissected out suspended in Ringer solution. Electrical stimulation resulted in release and increased synthesis of nonadrenaline.