STUDIES ON PORPHYRIN-HEME BIOSYNTHESIS IN ORGANOTYPIC CULTURES OF CHICK DORSAL ROOT-GANGLIA .2. EFFECT OF LEAD

Organotypic cultures of chick dorsal root ganglia retain the morphology and the metabolism of intact nervous tissues which are observed in vivo. Such cultures are capable of synthesizing porphyrins from a precursor, δ-aminolevulinic acid (ALA). The present study was undertaken to estimate the capacity of these cultures to form porphyrins from ALA and to study the effect of lead on porphyrin formation. Control cultures which were not incubated with ALA did not show detectable amounts of porphyrins. On the other hand, cultures incubated with ALA synthesized porphyrins linearly as a function of ALA concentration up to 2 mm as well as a function of incubation period for up to 24 hr. The major porphyrin synthesized by the cultures was uroporphyrin as demonstrated by its characteristic fluorescence emission spectrum and by its migration on thin-layer chromatographic plates. Porphyrin formation was inhibited 50% after treatment with lead at 10 μm; this was accompanied by a shift toward the formation of coproporphyrin and protoporphyrin. These results indicate that isolated chick dorsal root ganglion cultures are able to synthesize a full spectrum of porphyrins from ALA and that an inhibitory effect of lead on porphyrin formation can be demonstrated in such cultures. These data suggest the usefulness of organotypic cultures of chick dorsal root ganglia for the study of the effects of environmental chemicals on porphyrin - heme biosynthesis in isolated nervous tissues. © 1979.