CGRP-immunoreactive Cell Bodies Research Articles

Subarachnoid Hemorrhage Depletes Calcitonin Gene-Related Peptide Levels of Trigeminal Neurons in Rat Dura Mater.

Subarachnoid hemorrhage (SAH) remains a major cause of cerebrovascular morbidity, eliciting severe headaches and vasospasms that have been shown to inversely correlate with vasodilator calcitonin gene-related peptide (CGRP) levels. Although dura mater trigeminal afferents are an important source of intracranial CGRP, little is known about the effects of SAH on these neurons in preclinical models. The present study evaluated changes in CGRP levels and expression in trigeminal primary afferents innervating the dura mater 72 h after experimentally induced SAH in adult rats. SAH, eliciting marked damage revealed by neurological examination, significantly reduced the density of CGRP-immunoreactive nerve fibers both in the dura mater and the trigeminal caudal nucleus in the medulla but did not affect the total dural nerve fiber density. SAH attenuated ex vivo dural CGRP release by ~40% and in the trigeminal ganglion, reduced both CGRP mRNA levels and the number of highly CGRP-immunoreactive cell bodies. In summary, we provide novel complementary evidence that SAH negatively affects the integrity of the CGRP-expressing rat trigeminal neurons. Reduced CGRP levels suggest likely impaired meningeal neurovascular functions contributing to SAH complications. Further studies are to be performed to reveal the importance of impaired CGRP synthesis and its consequences in central sensory processing.

Calcitonin gene-related peptide immunoreactivity selectively labels accessory optic nuclei and pathways of the rat visual system.

The present study shows the distribution of calcitonin gene-related peptide (CGRP)-immunolabeled neuronal somata and fibers in the accessory optic system of adult rats. CGRP-immunoreactive cell bodies were small to medium-sized and mostly fusiform or oval-shaped. Both immunolabeled somata and fibers were found in the dorsal and lateral terminal nuclei as well as in the interstitial nucleus of the superior fasciculus (posterior fibers); whereas only immunoreactive fibers were found in the ventral division of the medial terminal nucleus, particularly its rostral portion. These results indicate that CGRP-containing neurons are present in all nuclear components of the accessory optic system and suggest that this neuropeptide may play a neuromodulative role in eye movements.

Neurochemical coding in the myenteric plexus of the upper gastrointestinal tract of hibernating hamsters

As part of our investigation of the plasticity of autonomic nerves in physiological and pathological conditions, we have examined the effect of hibernation on the neurochemical content of myenteric nerves and nerve cell bodies of the upper gastrointestinal tract of the non-seasonal hibernator, the golden hamster. Age matched hamsters kept at room temperature and those kept at 5°C but failed to hibernate, were used as controls. Possible changes in nerve fibers and nerve cell bodies containing the general neuronal marker, protein gene product 9.5, the peptides, vasoactive intestinal polypeptide, substance P (SP) and calcitonin gene-related peptide (CGRP), the catecholamine synthesizing enzyme tyrosine hydroxylase and the enzyme responsible for synthesizing nitric oxide, nitric oxide synthase, were examined in the oesophagus, proventriculus and proximal and distal stomach of the golden hamsters using immunohistochemical techniques. The results of the present study revealed a significant increase in the number of nerve cell bodies and density of nerve fibers containing SP-immunoreactivity and increased number of CGRP-immunoreactive cell bodies but not the other markers examined in the proximal stomach and proventriculus. In contrast, there was no change in the distribution of any of the neuroactive substances examined in the myenteric plexus of the oesophagus and distal stomach. It is suggested that the change in the environment of the hibernating hamsters perturbs the normal digestive physiology in the proximal stomach and proventriculus that is reflected by the selective changes in SP- and CGRP-containing enteric nerves; these changes may be part of protective reflex mechanisms to the environmental changes resulting from hibernation, where upgrading of nerve cell bodies expessing CGRP and SP has occurred.

Enteric innervation in idiopathic megarectum and megacolon.

We have studied the resection specimens from 5 patients with idiopathic megarectum and megacolon and 10 control subjects with non-obstructing colonic cancer. Histological staining with haematoxylin and eosin, and immunocytochemical staining for protein gene product 9.5 (PGP9.5), S100 protein, vasoactive intestinal polypeptide (VIP) and calcitonin gene-related peptide (CGRP), and histochemical localization of NADPH diaphorase was performed. The amount of VIP and CGRP present in samples was measured using an enzyme-linked immunosorbent assay. Patients with idiopathic megarectum and megacolon showed hypertrophy of the muscularis mucosae and muscularis externa. The architecture of the innervation as assessed by immunoreactivity for PGP9.5 and S100 protein appeared normal. There was a decrease in the density of innervation of the longitudinal muscle in rectal tissue from patients with idiopathic megarectum, with fewer VIP- and NADPH-diaphorase-containing nerves. In the muscularis mucosae and lamina propria of the rectal samples of patients with idiopathic megarectum, VIP immunoreactivity was higher and more NADPH-diaphorase-containing nerves were seen. CGRP-immunoreactive nerve fibres were only seen in the myenteric plexus. No CGRP-immunoreactive cell bodies were seen. In summary, there is an increase in VIP and nitric oxide containing fibres in the muscularis mucosae and lamina propria and a decrease in the longitudinal muscle in rectal tissue of patients with idiopathic megarectum. Both are NANC (nonadrenergic noncholinergic) inhibitory transmitters in the gut and the possible relationship of the changes in their density with gut function is discussed.

Structure, afferent innervation, and transmitter content of ganglia of the guinea pig gallbladder: Relationship to the enteric nervous system

Although a well-developed plexus of nerves and ganglia is known to be present in the wall of the gallbladder, little has previously been learned about the function or organization of this innervation. The current study was undertaken in order to evaluate the hypothesis that the ganglionated plexus of the gallbladder is analogous to elements of the enteric nervous system (ENS). The ganglionated plexus of the gallbladder was found to resemble closely the submucosal plexus of the small intestine in its organization into two irregular anastomosing and interwoven networks of ganglia, in the numbers of neurons per ganglion, and in the manifestation of histochemically demonstrable acetylcholinesterase activity in virtually all ganglion cells. In common with enteric ganglia, laminin immunoreactivity was observed to be excluded from the interiors of gallbladder ganglia, which were surrounded by a periganglionic laminin-immunoreactive sheath. As in the submucosal plexus, intrinsic substance P-, vasoactive intestinal polypeptide (VIP)-, and neuropeptide Y (NPY)-immunoreactive neurons were seen in the ganglionated plexus of the gallbladder. Extrinsic nerves in the gallbladder that degenerated following chemical sympathectomy with 6-hydroxydopamine (6-OHDA), and which contained NPY, tyrosine hydroxylase (TH), and dopamine-beta-hydroxylase (DBH) immunoreactivities, formed a perivascular plexus closely associated with blood vessels. Endogenous catecholamines could also be demonstrated in these perivascular nerves by aldehyde-induced histofluorescence. In addition to perivascular nerves, paravascular nerve bundles were observed that were loosely associated with vessels, did not degenerate following administration of 6-OHDA, and contained NPY immunoreactivity. Other paravascular nerves, probably visceral sensory axons, coexpressed substance P and calcitonin-gene-related peptide (CGRP) immunoreactivities. The ganglionated plexus of the gallbladder resembled enteric ganglia in having intrinsic 5-hydroxytryptamine (5-HT)-immunoreactive cells and highly varicose nerve fibers. The 5-HT-immunoreactive gallbladder axons were, like those of the gut, resistant to 6-OHDA, and separate from fibers that expressed TH immunoreactivity. Differences between the ganglionated plexus of the gallbladder and enteric ganglia of the small intestine included in the gallbladder are 1) the presence of TH-immunoreactive cells that contain an endogenous catecholamine, but not DBH; 2) DBH-immunoreactive neurons, some of which coexpress substance P immunoreactivity, but which contain neither a catecholamine nor TH immunoreactivity; 3) an apparent absence of CGRP-immunoreactive cell bodies.(ABSTRACT TRUNCATED AT 400 WORDS)

Calcitonin Gene-Related Peptide in the Human Hypothalamus.

Calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) in the human hypothalamus was investigated by radioimmunoassay and by immunocytochemistry. CGRP-LI was detected from two hypothalami obtained at autopsy (2.1 and 7.0 ng/g wet tissue) by radioimmunoassay. Reverse phase high performance liquid chromatography revealed that most of the CGRP-LI in the human hypothalamus was eluted in an identical position with synthetic human CGRP. For immunocytochemistry, human hypothalami obtained at autopsy were fixed and cryostat-sectioned at 40 microns. Free floating sections were immunostained with antibody to CGRP. CGRP-immunoreactive cell bodies were found in the supraoptic nucleus, paraventricular nucleus and infundibular nucleus. These findings indicate that CGRP exists in the cell bodies of the supraoptic nucleus, paraventricular nucleus and infundibular nucleus in the human hypothalamus and CGRP may play some roles in the endocrine and other functions of the human hypothalamus.

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.