Calcitonin gene-related peptide (CGRP) immunoreactivity was found throughout the entire spinal cord of man, marmoset, horse, pig, cat, guinea pig, mouse, rat, and frog. CGRP-immunoreactive fibers were most concentrated in the dorsal horn. In the ventral horn of some species large immunoreactive cells, tentatively characterized as motoneurons, were present. Pretreatment of rats with colchicine enhanced staining of these large cells but did not reveal CGRP-immunoreactive cell bodies in the dorsal horn. In the dorsal root ganglia, CGRP immunoreactivity was observed in most of the small and some of the intermediate sized cells. Substance P immunoreactivity, where present, was co-localized with CGRP to a proportion of the small cells. In the cat the ratio of substance P-immunoreactive to CGRP-immunoreactive ganglion cells was 1:2.7 (p less than 0.001). The concentration of CGRP-immunoreactive material in tissue extracts was determined by radioimmunoassay. In the dorsal horn of the rat spinal cord the levels of peptide were found to range from 225.7 +/- 30.0 pmol/gm of wet weight in the cervical region to 340.6 +/- 74.6 pmol/gm in the sacral spinal cord. In the rat ventral spinal cord, levels of 15.7 +/- 2.7 to 35.1 +/- 10.6 pmol/gm were found. The concentration in dorsal root ganglia of the lumbar region was 225.4 +/- 46.9 pmol/gm. Gel permeation chromatography of this extractable CGRP-like immunoreactivity revealed three distinct immunoreactive peaks, one eluting at the position of synthetic CGRP and the others, of smaller size, eluting later. In cats and rats, rhizotomy induced a marked loss of CGRP-immunoreactive fibers from the dorsal horn of the spinal cord. In the cat, unilateral lumbosacral dorsal rhizotomy resulted in a significant (p less than 0.05) reduction of extractable CGRP from the ipsilateral lumbar dorsal horn (5.6 +/- 1.2 pmol/gm of wet weight) compared to the contralateral side (105.0 +/- 36.0 pmol/gm of wet weight). We conclude that the major origin of CGRP in the dorsal spinal cord is extrinsic, from afferent fibers which are probably derived from cells in the dorsal root ganglia. The selective distribution of CGRP throughout sensory, motor, and autonomic areas of the spinal cord suggests many putative roles for this novel peptide.

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Plasma concentrations of endothelin, a vasoconstrictor peptide released from vascular endothelial cells, have been measured by radioimmunoassay in 100 patients with diabetes mellitus and 19 healthy subjects. The plasma immunoreactive-endothelin concentrations were found to be greatly raised in the patients with diabetes (1,880 +/- 120 fmol/l, mean +/- SEM) compared with the healthy subjects (540 +/- 50 fmol/l, p less than 0.005). The elevation of immunoreactive-endothelin could not be explained by secondary changes in blood pressure or renal disease and did not correlate with the presence of diabetic retinopathy, duration of diabetes mellitus, fasting blood glucose or serum fructosamine. Fast protein liquid chromatographic analysis of the diabetic plasma immunoreactive-endothelin showed three forms, one in a very big molecular weight position, one intermediate and one in the position of endothelin-1 itself. No material appeared in the positions of endothelin-2 and 3. Chromatographic analysis of normal plasma showed only the big molecular weight peak while material in the endothelin-1, 2 or 3 positions was below detection. The elevation of endothelin in diabetic patients may be a marker of, and further exacerbate, their vascular disease.

The distribution of a novel neuropeptide, pituitary adenylate cyclase-activating polypeptide (PACAP), was studied in the brain of the rat and man and a variety of other rat tissues using Northern blot hybridization and two radioimmunoassays for PACAP 1-38 and PACAP 1-27. The assay, using PACAP 1-38 as standard and an antibody to PACAP 21-38 and radiolabelled tracer, revealed immunoreactive PACAP in all brain regions examined, with the highest concentrations in the rat being in the hypothalamus, nucleus accumbens and substantia nigra (380 +/- 34, 310 +/- 37 and 346 +/- 30 pmol/g wet tissue, means +/- S.E.M., n = 5 respectively), whilst in man the highest concentrations were found in the pituitary gland (15.8 +/- 4.7 pmol/g). Immunoreactive PACAP 1-38 was also detected in the rat gastrointestinal tract, adrenal gland and testis. The assay using PACAP 1-27 as standard and label and an antibody to PACAP 1-27 detected immunoreactive PACAP only in the rat hypothalamus (12.6 +/- 1.8 pmol/g wet tissue, n = 5). PACAP mRNA of approximately 2.7 kb in size was detectable in all brain regions of both rat and man, and its distribution paralleled that of the immunoreactive peptide. Gel permeation chromatography of different regions of human and rat hypothalamus, and also rat spinal cord and small intestine, showed a broad immunoreactive peak corresponding to PACAP 1-38. Fast protein liquid chromatography (FPLC) resolved this peak into two immunoreactive peaks, the majority eluting in the position of synthetic PACAP 1-38.(ABSTRACT TRUNCATED AT 250 WORDS)