CGRP-immunoreactive Fibers Research Articles

Calcitonin gene-related peptide: Detailed immunohistochemical distribution in the central nervous system

With the use of an antiserum generated in rabbits against synthetic human calcitonin gene-related peptide (CGRP) the distribution of CGRP-like immunoreactive cell bodies and nerve fibers was studied in the rat central nervous system. A detailed stereotaxic atlas of CGRP-like neurons was prepared. CGRP-like immunoreactivity was widely distributed in the rat central nervous system. CGRP positive cell bodies were observed in the preoptic area and hypothalamus (medial preoptic, periventricular, anterior hypothalamic nuclei, perifornical area, medial forebrain bundle), premamillary nucleus, amygdala medialis, hippocampus and dentate gyrus, central gray and the ventromedial nucleus of the thalamus. In the midbrain a large cluster of cells was contained in the peripeduncular area ventral to the medial geniculate body. In the hindbrain cholinergic motor nuclei (III, IV, V, VI, VII XII) contained CGRP-immunoreactivity. Cell bodies were also observed in the ventral tegmental nucleus, the parabrachial nuclei, superior olive and nucleus ambiguus. The ventral horn cells of the spinal cord, the trigeminal and dorsal root ganglia also contained CGRP-immunoreactivity. Dense accumulations of fibers were observed in the amydala centralis, caudal portion of the caudate putamen, sensory trigeminal area, substantia gelatinosa, dorsal horn of the spinal cord (laminae I and II). Other areas containing CGRP-immunoreactive fibers are the septal area, nucleus of the stria terminalis, preoptic and hypothalamic nuclei (e.g., medial preoptic, periventricular, dorsomedial, median eminence), medial forebrain bundle, central gray, medial geniculate body, peripeduncular area, interpeduncular nucleus, cochlear nucleus, parabrachial nuclei, superior olive, nucleus tractus solitarii, and in the confines of clusters of cell bodies. Some fibers were also noted in the anterior and posterior pituitary and the sensory ganglia. As with other newly described brain neuropeptides it can only be conjectured that CGRP has a neuroregulatory action on a variety of functions throughout the brain and spinal cord.

Calcitonin gene-related peptide (CGRP)-immunoreactive sensory and motor nerves of the mammalian palate.

The distribution of calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibres in the palate of rat, cat and monkey was studied using immunocytochemistry and radioimmunoassay. CGRP-containing nerve fibres were found, in all species studied, to form a rich plexus in the subepithelial and submucous layers, around excretory ducts and blood vessels. A small number of CGRP-containing nerve fibres penetrated the epithelium of the hard and soft palate, and terminated as free endings. Some CGRP-containing nerve fibres were found in the vicinity of the mucous glands. CGRP-immunoreactive motor end plates were seen in the striated muscle (tensor veli palatini) of the soft palate. Following capsaicin treatment a small depletion in CGRP-immunoreactive nerve fibres in the rat palate epithelium was noted. In contrast, CGRP immunoreactive fibres forming rich plexuses in other layers of the palate, including motor end plates, were not affected. The extractable CGRP showed no significant depletion (normal animals [n = 10] 21.7 +/- 2.4 pmol/g compared with capsaicin-treated animals [n = 10] 17.5 +/- 1.8 pmol CGRP/g wet weight). The reduction in the number of visible immunoreactive nerves following capsaicin application tends to confirm the sensory character of the CGRP-containing nerve fibres terminating in the epithelium of the hard and soft palate. The capsaicin insensitive CGRP-immunoreactive nerve fibres may thus have a predominantly motor function.(ABSTRACT TRUNCATED AT 250 WORDS)

The distribution of calcitonin gene related peptide in the rat peripheral nervous system and thyroid gland

Our study investigates the distribution of neurophysins (Nph), proteins that are part of the precursors for vasopressin and oxytocin, and calcitonin gene-related peptide (CGRP) in the human brainstem by immunohistochemistry. Both peptides were found in discrete regions of the human hindbrain. Nph could be demonstrated exclusively in fibers and punctate perineural varicosities that were travelling within the mesencephalic central gray, substantia nigra, as well as locus coeruleus, medial longitudinal fascicle, raphe, nucleus of the solitary tract, lateral reticular nucleus and area postrema. A few varicosities were seen in the substantia gelatinosa of the spinal trigeminal tract and its continuation into the dorsal horn of the cervical spinal cord. In contrast to these observations, CGRP-immunoreactive fibers were found to be densest in the spinal tract of the trigeminal nerve and the dorsal horn of the spinal cord. In addition, fibers and varicosities could be demonstrated in numerous distinct brain regions, such as locus coeruleus and subcoeruleus, solitary tract, cuneate nucleus, raphe and periaqueductal gray. CGRP-immunoreactivity was also present in perikarya in the ventral horn of the spinal cord, as well as motor nuclei of cranial nerves, i.e. hypoglossal nucleus, ambiguus nucleus. Our results suggest that Nph-immunoreactivity in the human brainstem may be present predominantly within long fiber projections from hypothalamic neurosecretory nuclei, in analogy to data obtained from rodents, whereas CGRP may play a role in the branchiomotor system as well as in intrinsic or extrinsic projections involved in autonomic regulation and integration of sensory information.

Immunohistochemical evidence for the coexistence of calcitonin gene-related peptide- and choline acetyl transferase-like immunoreactivity in the rat brain

Our study investigates the distribution of neurophysins (Nph), proteins that are part of the precursors for vasopressin and oxytocin, and calcitonin gene-related peptide (CGRP) in the human brainstem by immunohistochemistry. Both peptides were found in discrete regions of the human hindbrain. Nph could be demonstrated exclusively in fibers and punctate perineural varicosities that were travelling within the mesencephalic central gray, substantia nigra, as well as locus coeruleus, medial longitudinal fascicle, raphe, nucleus of the solitary tract, lateral reticular nucleus and area postrema. A few varicosities were seen in the substantia gelatinosa of the spinal trigeminal tract and its continuation into the dorsal horn of the cervical spinal cord. In contrast to these observations, CGRP-immunoreactive fibers were found to be densest in the spinal tract of the trigeminal nerve and the dorsal horn of the spinal cord. In addition, fibers and varicosities could be demonstrated in numerous distinct brain regions, such as locus coeruleus and subcoeruleus, solitary tract, cuneate nucleus, raphe and periaqueductal gray. CGRP-immunoreactivity was also present in perikarya in the ventral horn of the spinal cord, as well as motor nuclei of cranial nerves, i.e. hypoglossal nucleus, ambiguus nucleus. Our results suggest that Nph-immunoreactivity in the human brainstem may be present predominantly within long fiber projections from hypothalamic neurosecretory nuclei, in analogy to data obtained from rodents, whereas CGRP may play a role in the branchiomotor system as well as in intrinsic or extrinsic projections involved in autonomic regulation and integration of sensory information.

Calcitonin gene-related peptide immunoreactivity in the spinal cord of man and of eight other species

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.