CATECHOL-O-METHYLTRANSFERASE IN RAT SENSORY GANGLIA AND SPINAL-CORD

The localization of catechol-O-methyltransferase immunoreactivity in r at dorsal root ganglia and in the spinal cord and its co-existence wit h substance P, calcitonin gene-related peptide and fluoride-resistant acid phosphatase in dorsal root ganglion cells was examined with immun ohistochemical and histochemical double-staining methods. Analysis of dorsal of dorsal root ganglia at both cervical and lumbar levels revea led catechol-O-methyltransferase immunoreactivity in numerous dorsal r oot ganglion cells. Double-staining studies showed that catechol-O-met hyltransferase and substance P immunoreactivities were located in diff erent cells with a few exceptions, whereas both catechol-O-methyltrans ferase and calcitonin gene-related peptide immunoreactivities were det ected in about 10% of all labeled cells positive for one of the two ma rkers at both levels studied. The great majority of fluoride-resistant alkaline phosphatase-positive cells were also immunoreactive for cate chol-O-methyltransferase. Again, no difference was found between cervi cal and lumbar levels. Catechol-O-methyltransferase immunoreactivity w as also found in the neuropil of the dorsal horn of the spinal cord. T he staining was most intense in the superficial laminae (I-III) and ov erlapped partly with substance P and calcitonin gene-related peptide i mmunoreactivity. Western blotting analysis revealed that soluble catec hol-O-methyltransferase was the clearly dominating form of the enzyme in dorsal root ganglia. The distribution pattern of catechol-O-methylt ransferase in dorsal horn and sensory neurons suggests that the enzyme may modulate sensory neurotransmission. (C) 1996 IBRO. Published by E lsevier Science Ltd.