Localization Of Calcitonin Gene-related Peptide Research Articles

Autoradiographic localization of calcitonin gene-related peptide binding sites in human and rat brains

125I-calcitonin gene-related peptide (CGRP) binding sites were mapped in the human brain and rat brains by in vitro macroautoradiography, and compared to each other. Binding experiments were made to characterize 125I-CGRP binding on the human and rat brains. Scatchard analysis of saturation experiments from slide-mounted sections of the human and rat cerebellum displayed 125I-CGRP binding sites with a dissociation constant ( K d ) of 0.17 nM and 0.11 nM, respectively, and a maximal number of binding sites (B max) of 96.8 fmol/mg and 23.0 fmol/mg protein. 125I-CGRP binding was time-dependent, reversible and saturable with high affinity in the brains. Autoradiograms showed a discrete distribution of 125I-CGRP binding sites throughout the brains of human and rat with patterns similar to each other. In the human brain, the highest binding was seen in the cerebellum, inferior olivary nuclear complex, certain parts of the central gray matter, arcuate nuclei of the medulla oblongata and dorsal motor nucleus of the vagus, and densities of CGRP-binding sites were high in the nucleus accumbens, amygdala, tail of the nucleus caudatus, substantia nigra, ventral tegmental area, medial portion of the inferior colliculus, medial pontine nuclei, locus coeruleus, inferior vestibular nucleus, substantia gelatinosa of the spinal trigeminal nucleus, nucleus of the solitary tract and nucleus cuneatus lateralis. In the rat, high densities were found in the hippocampus pars anterior, nucleus accumbens, ventral and caudal portions of the nucleus caudatus-putamen, central and basolateral nuclei of the amygdala, caudal portion of the insular cortex, medial geniculate body, superior and inferior colliculi, certain portions of the central gray matter, locus coeruleus, inferior olivary nuclei, vagal complex, nucleus cuneatus lateralis and cerebellum. In contrast, in both species, most of the cortical areas including the hippocampus, most of the thalamus, and hypothalamus exhibited few binding sites. In addition, high quantities of the binding sites were seen on the pia mater and on walls of blood vessels in the brain and subarachnoidea. These results revealed essentially homologous locations of CGRP binding sites in the human and rat central nervous systems and well corresponding distributions of binding sites and endogenous CGRP-like immunoreactivity.

Cardiovascular effects produced by microinjection of calcitonin gene-related peptide into the rat central amygdaloid nucleus

Recent studies have provided evidence for a dense localization of calcitonin gene-related peptide (CGRP) and its receptors within the central amygdaloid nucleus (Ce) in rat brain. Since this nucleus has been thought to play a role in central cardiovascular regulation, the present study examined the cardiovascular effects subsequent to the microinjection of CGRP into the Ce. Doses of 50–500 pmol of CGRP produced a significant elevation of 11–15% in systolic, diastolic and mean arterial pressures. Heart rate was significantly elevated by 16–18% by these doses of CGRP. The time course of the effects of CGRP revealed that onset of action occurred after 15–20 min, peak effects were seen at approximately 30–40 min after onset and the effects of the peptide usually lasted for at least 2 hr, after which time BP and HR values returned to baseline. The present study demonstrates that CGRP produces significant increases in both BP and HR when pmol doses of the peptide are injected into the Ce. It is suggested that in the Ce, CGRP plays a neuromodulatory role in cardiovascular function.

Localization of calcitonin gene-related peptide in the organ of Corti of the rat: an immunohistochemical study

The localization of calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRPI) structures in the cochlea was examined in the rat using immunocytochemistry. Numerous CGRPI fibers entered the organ of Corti in the intraganglionic spiral bundle and formed a dense fiber patch at the base of the inner hair cells. Much fewer, but still a significant number of CGRPI fibers were seen at the synaptic region of the outer hair cells. Since no immunoreactive cells were seen in the organ of Corti and spinal ganglion, these fibers may be one of the major components of the olivocochlear bundles originated from the superior olivary complex.

Topographic localization of calcitonin gene-related peptide in the rat brain: An immunohistochemical analysis

The distribution of immunoreactive calcitonin gene-related peptide in the rat brain was investigated by means of an indirect immunofluorescence method. In addition to previously reported calcitonin gene-related peptide-like immunoreactive structure-containing sites such as the nucleus ambiguus, nucleus originis nervi facialis, nucleus originis nervi hypoglossi, nucleus peripeduncularis and nucleus parabrachialis, the present study demonstrated a far wider distribution of calcitonin gene-related peptide-like immunoreactive structure-containing cells in the rat brain, i.e. the nucleus hypothalamicus lateralis. nucleus ventromedialis thalami, colliculus superior, lemniscus lateralis, gyrus dentatus. nucleus olivaris superior, nucleus tractus solitarii, nucleus cuneiformis, nucleus parabigeminalis and a proportion of the Purkinje cells. We have also demonstrated a more extensive network of calcitonin gene-related peptide-like immunoreactive fibers distributed in various areas throughout the rat brain than has been reported previously such as the colliculus inferior, nucleus olivaris superior, nucleus vestibularis lateralis and inferions, and nucleus cochlearis dorsalis and ventralis, etc.

Coexistence of calcitonin gene-related peptide and substance P-like peptide in single cells of the trigeminal ganglion of the rat: immunohistochemical analysis

The localization of calcitonin gene-related peptide (CGRP) and substance P (SP) in the rat trigeminal ganglion was examined by means of the indirect immunofluorescent method. About 40% of neurons in the ganglion contained CGRP-like immunoreactivity (CGRPI), while about 20% of neurons showed SP-like immunoreactivity (SPI). In serial sections, nearly all the SPI neurons contained CGRPI.

Topographic localization of calcitonin gene-related peptide in the rat brain: An immunohistochemical analysis

The efferent connections of the ventral medulla oblongata have been analyzed in the rat using the anterograde autoradiographic method and the HRP technique. Fibers originating from the nucleus interfascicularis hypoglossi (B1 serotonergic cell group) and nucleus reticularis gigantocellularis, pars a (B3 serotonergic cell group) innervate the intermediolateral cell column, ventral horn and intermediate gray matter of the spinal cord. Some fibers innervate the hypoglossal, dorsal motor vagal, and medial solitary nuclei. Ascending fibers project through the medullary and pontine reticular formation, providing inputs to the Kölliker-Fuse, lateral parabrachial, laterodorsal tegmental, subcoeruleus and locus coeruleus nuclei. In the midbrain, the fibers ascend in the central tegmental field and then divide into several fiber bundles. Some course medially to innervate the central gray matter. Others diverge laterally to innervate the external nucleus of the inferior colliculus and cuneiform nucleus as well as the deep layers of the contralateral superior colliculus. Still others course dorsally through the ventral pretectal region to reach the thalamus (laterodorsal, paraventri-cular, paracentral, and centrolateral thalamic nuclei). The remaining fibers innervate the hypothalamus (dorsal hypothalamic area, paraventricular nucleus, perifornical area, supraoptic nucleus, retrochiasmatic area, and median eminence). Some of these continue through the lateral preoptic region, shift medially as they course through the area of the nucleus of the diagonal band, septofimbrial nucleus, and medial septum, and arch around the genu of the corpus callosum to innervate the hippocampal formation.

Topographic localization of calcitonin gene-related peptide in the rat brain: An immunohistochemical analysis

Topographic localization of calcitonin gene-related peptide in the rat brain: An immunohistochemical analysis