Fluorescence microscopical demonstration of 5-hydroxydopamine in adrenergic nerves

Summary It is demonstrated that 5-hydroxydopamine (5HDA) is capable of forming highly fluorescent products with formaldehyde under conditions suitable for histochemical analyses. Prom absorptiometric and fluorometric studies it is reasonable to assume that the fluorophores formed are isoquinolines, in analogy with the reaction between, e.g., dopamine and formaldehyde. The reaction proceeds readily in protein layers and actual nerve terminals in tissues, allowing demonstration and identification of 5HDA in tissue structures. From studies on rat irides it is demonstrated that only adrenergic terminals take up 5HDA in demonstrable amounts.This work was supported by grants from the Swedish Medical Research Council (B69-14X-712-04C and B69-14X-2321-02), Knut och Alice Wallenbergs stiftelse and the Faculty of Medicine, University of Lund.