TY - JOUR T1 - ON THE POSSIBLE EXISTENCE OF A NEW INTRANEURONAL MONOAMINE IN THE SPINAL CORD OF THE RAT JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 525 LP - 532 VL - 175 IS - 2 AU - ANDERS BJÖRKLUND AU - BENGT FALCK AU - ULF STENEVI Y1 - 1970/11/01 UR - http://jpet.aspetjournals.org/content/175/2/525.abstract N2 - Intraneuronal monoamines have been studied with the histochemical fluorescence method of Falck and Hillarp in the rat spinal cord. The formaldehyde-inducedintrancuronal fluorophores have been analyzed with microspectrofluorometry in combination with drugs which deplete monoamines from the central nervous system. Three types of intraneuronal fluorescence were found. 1) A green fluorescence, with spectra identical with those of the catecholamine fluorophores, which was depleted by reserpine and α-methyl-m-tyrosine but not by p-chlorophenylalanine, was found. This fluorescence was most likely derived from Primary catecholamines. 2) A yellow fluorescence, with spectra identical with those of the 5-hydroxytryptamine fluorophore, which was depleted by reserpine and p-chlorophenylalanine but not by α-methyl-m-tyrosine, was found. This fluorescence was probably derived from 5-hydroxytryptamine. 3) A yellow to brownish-yellow fluorescence, with spectra clearly deviating from those of the catecholamine and the 5-hydroxytryptamine fluorophores, which was depleted by reserpine but not by p-chlorophenylalanine or α-methyl-m-tyrosine, was found. Moreover, this fluorescenceshowed upon ultraviolet irradiation a photodecomposition rate, which was markedly slower than that of the 5-hydroxytryptamine fluorophore. These results strongly indicate that this intraneuronal fluorogenic substance is not identical with a catecholamine or 5-hydroxytryptamine. The spectral characteristics of this third type of fluorescence showed general features characteristic for many indolykthylamines. © 1970 by The Williams & Wilkins Co. ER -