Showing papers by "Anders Björklund published in 1969"

Histochemical characterization of a tryptamine-like substance stored in cells of the mammalian adenohypophysis.

Abstract: A recently developed, sensitive fluorescence method for the histochemical localization and the microspectrofluorimetric characterization of tryptamine (Bjorklund, Falck and HBkanson 1968) has been applied to the pituitary gland of the rat, cat, and pig. In all three species, most of the cells of the pars intermedia and many cells in the pars distalis were found to store a substance in the cytoplasm that could be transformed to a highly fluorescent derivative under the special reaction conditions required to obtain a high fluorescence yield of tryptamine. This pituitary fluorophore, moreover, showed the same microspectrofluorimetric characteristics under various conditions as does the tryptamine fluorophore. These histochemical and microspectrofluorimetrc characteristics differ clearly from those exhibited by a number of catechol and indole compounds, including the biogenic catecholamines, 5-hydroxytryptamine and tryptophan. The reliability and the significance of the histochemical criteria are discussed, and it is concluded that there is much to support the view that tryptamine, or a closely related β(3–1ndolyl)ethylamine, is stored in the adenohypophysis. Another fluorophore that may derive from a hitherto unknown biogenic phenylethylamine was disclosed in a large number of pars distalis cells not identical with those that possibly store tryptamine.

An enzymic barrier mechanism for monoamine precursors in the newly-forming brain capillaries following electrolytic or mechanical lesions.

Abstract: — The intracerebral capillaries of the rat constitute an enzymic trapping mechanism for certain systemically administered monoamine precursors, which are taken up into the capillary walls, decarboxylated locally to the corresponding amine and this is then metabolized by monoamine oxidase. The amine can be directly demonstrated histochemically in the endothelial cells and pericytes of the capillaries, particularly after inhibition of monoamine oxidase. The question of whether or not these barrier properties appear also in the regenerating capillaries following electrolytic or mechanical lesions in the cerebellar parenchyma was studied after intraperitoneal injection of l-DOPA to rats pretreated with nialamide. A very pronounced formation of new capillaries, starting at the periphery of the lesions, could be established 3–4 weeks postoperatively. Also these new, regenerating capillaries were able to trap l-DOPA in a manner indistinguishable from that of the normal capillaries in the surrounding parenchyma. It is concluded that a complete barrier mechanism with regard to the enzymic trapping of certain monoamine precursors can reestablish after complete regeneration of the brain capillary bed in unspecific lesions.

Failure of Neonatally Administered Reserpine To Affect the Hypothalamic Catecholamines in the Adult Rat

Abstract: Young rats were treated with reserpine for various periods during the first 15 days of life and killed at the age of 4–6 months. Compared with their litter-mate controls, no effect of the early reserpine treatment was observed in the distributional pattern and intensity of the catecholamine fluorescence in the histochemical preparations, and no obvious difference was found in the whole-brain catecholamine content between reserpine-treated and control animals. No effect of the early reserpine treatment on the incidence of vaginal cornification could be established. (Endocrinology 85: 788, 1969)