Immunohistochemical studies of cholecystokininlike peptides and their relation to 5-HT, CGRP, and bombesin immunoreactivities in the brainstem and spinal cord of lampreys

The distribution of cholecystokinin (CCK)-like immunoreactivity in the brainstem and spinal cord of lampreys was studied by using CCK antisera with different properties. In the spinal cord, three separate systems reacted with CCK antisera: (1) A ventral and lateral fiber system descending from a group of neurons in the posterior reticular nucleus of the rhombencephalon was labeled by both a C-terminal-directed CCK antiserum and a monoclonal CCK antibody. (2) A dorsal root-dorsal column system of fibers originating from cell bodies in the dorsal root ganglia was labeled only by the C-terminal CCK antiserum. This CCK immunoreactivity could be abolished by preabsorption with calcitonin-gene-related peptide (CGRP), suggesting that it was due to cross-reactivity with a CGRP-like peptide. This system also contained 5-hydroxytryptamine (5-HT)-, bombesin-, and CGRP-like immunoreactivities. (3) An intraspinal system of 5-HT neurons was labeled with an antiserum to the midportion of CCK-33 but not by the other CCK antisera. The CCK labeling of this system was difficult to reduce by preabsorption with CCK peptide and thus appeared to be nonspecific. Groups of cell bodies in the middle reticular nucleus of the rhombencephalon, the reticular nucleus of the mesencephalon, and the hypothalamus were labeled by both the C-terminal and the monoclonal CCK antisera. The gut contained two types of CCK-like immunoreactivity, one of which appeared to be due to cross-reactivity with CGRP. A biochemical analysis showed that the content of CCK was low in the spinal cord compared to the brain, and these results agreed with the immunohistochemical findings.     

Immunohistochemical study of cholecystokinin peptide in rat spinal motoneurons.

With the aid of indirect immunofluorescence histochemistry and sequence specific antibodies a possible localization of cholecystokinin (CCK) peptide in spinal motoneurons has been analyzed. To increase peptide levels, the sciatic nerve was ligated, and the area around the ligation was studied 24 hours later. For comparison, antisera raised against calcitonin gene-related peptide (CGRP) and substance P were employed. With CCK specific antisera (directed to the N-terminal portion of CCK-8 or the midportion of CCK-33) accumulation of peptide-like immunoreactivity (LI) was observed in large, dilated axonal swellings proximal to, but at some distance from, the ligature. Such accumulations were also observed with C-terminally directed CCK antiserum, but in addition numerous axons of smaller diameter extending up to the ligation contained this type of immunoreactivity. The latter antiserum is thought to cross-react with CGRP. In fact, this staining pattern was indistinguishable from the one seen after incubation with CGRP antiserum. In contrast substance P-LI could not be seen in the larger dilated axons but only in large numbers of thinner fibers close to the ligation. Double staining experiments revealed that the large dilations contained both CGRP- and CCK-specific LI. Distal to the ligation CGRP- and substance P- but no specific CCK-LI could be observed. The present findings support the view that CCK mRNA in spinal motoneurons is translated into CCK peptide, at least after axotomy, and that the peptide is transported into the motoneuron axon. However, compared to CGRP the CCK levels are presumably low, and the functional role of CCK peptide in motoneurons remains to be established.     

Regional differences in the development of cholecystokinin-like activity in rat brain

The postnatal development of cholecystokinin (CCK) in rat brain was studied by radioimmunoassay and bioassay of tissue extracts. Marked differences were found in the patterns of development in different regions of the brain. In the cerebellum and brainstem of newborn rats the concentrations of CCK8-like immunoreactivity were 40-100% those in adults, whereas in more rostral regions the concentrations were 1-10% of those in adults. Between 0 and 14 days in concentrations of CCK-like activity measured by radioimmunoassay increased up to 30-fold in hypothalamus, cortex and olfactory bulb; in the cortex there were further increases up to 42 days. Cortical CCK was also measured by bioassay on rabbit gall bladder in vitro; bioactivity was identified in foetuses, and after birth showed a similar pattern of increase to that measured by radioimmunoassay. Immunoreactive material in extracts of neonatal cerebellum, brainstem and cortex was identified as CCK8 on the basis of cross-reactivity with different antisera, and chromatographic properties on gel filtration. The results raise the possibility of different rates of maturation of central CCKergic systems.     

The distribution of cholecystokinin immunoreactivity in the central nervous system of the rat as determined by radioimmunoassay

The regional distribution of cholecystokinin (CCK) in the rat brain was determined utilizing a radioimmunoassay which detects both gastrin and CCK. CCK concentration is highest in the caudate nucleus (10–14 ng CCK8 equivalents/mg protein), followed by the cerebral cortex. Within the cerebral cortex, CCK is highest in the cingulate, pyriform, and entorhinal areas. There are substantial CCK concentrations in all other brain regions except pons, medulla and cerebellum. CCK is widely distributed in the hypothalamus, where it is highest in the median eminence and ventromedial nucleus. Considerable CCK-like immunoreactivity is also present in the posterior lobe of the pituitary gland, but is not detectable in anterior and intermediate lobes.Though the antisera used in this study cross-react with gastrin the dominant CCK-like material found in rat brain co-elutes with sulfated CCK8 and separates from gastrin on Sephadex G-25 and HPLC chromatography.     

Cholecystokinin-like peptide is a modulator of a crustacean central pattern generator

The presence, release, and physiological effects of a cholecystokinin(CCK)-like peptide within the stomatogastric ganglion (STG) of the lobster, Panulirus interruptus, are described. Indirect immunofluorescence with 2 antisera raised against CCK8 was used to determine the distribution of CCK-like immunoreactivity (CCKLI) in the stomatogastric nervous system. CCKLI was demonstrated in the input nerve and the neuropil of the STG and in neuropil and somata in the commissural ganglia (CGs), brain, and eyestalks. None of the somata within the STG displayed CCKLI. The cross-reactivities of the CCK antisera with several peptides were determined using either a radioimmunoassay or an immunoblot assay; the antisera recognized peptides homologous to CCK but did not cross-react significantly with several unrelated peptides. The STG contains 2 central pattern generators (CPGs), the pyloric and the gastric mill CPGs. Bath application of CCK8 to the STG had modulatory effects on both CPGs, which were dose dependent and reversible. CCK increased the spike frequencies and number of spikes per burst of the pyloric rhythm but had little effect on the period. CCK increased the period of the gastric rhythm and produced changes in the spike frequencies, burst lengths, and phases of gastric units. High concentrations of peptide were needed to produce these effects (10(-6) to 10(-4) M). Finally, stimulation of the stomatogastric nerve (stn), which contains fibers immunoreactive to CCK, produced calcium-dependent release of CCK molar equivalents (CCKE) into the STG. The stn was electrically stimulated and the superfusate around the ganglion was collected and assayed for CCKE using a radioimmunoassay. Stimulation produced the release of 37.1 +/- 7.1 fmol (mean +/- SEM), compared to 13.7 +/- 4.9 fmol for unstimulated controls and 4.9 +/- 2.9 fmol in the absence of calcium. These data suggest that a CCK-like peptide is an endogenous modulator of the stomatogastric ganglion of P. interruptus.     

Cholecystokinin in Mammalian Primary Sensory Neurons and Spinal Cord: In Situ Hybridization Studies in Rat and Monkey

The peptide cholecystokinin (CCK) has been suggested to be involved in nociception, but its exact localization at the level of the spinal cord and in spinal ganglia has been a controversial issue. Therefore the distribution of messenger RNA (mRNA) for CCK was studied by in situ hybridization using oligonucleotide probes on sections of adult rat lumbar dorsal root ganglia following unilateral section of the sciatic nerve and on sections of untreated monkey trigeminal ganglia, spinal cord and spinal ganglia from all levels. For comparison, calcitonin gene-related peptide (CGRP) mRNA was also studied in the monkey tissue using the same techniques. Peripheral sectioning of the sciatic nerve in the rat resulted in the appearance of detectable CCK mRNA in up to 30% of remaining ipsilateral L4 and L5 dorsal root ganglion neurons 3 weeks after surgery, with a distinct but more limited appearance also in the contralateral ganglia. No cells, or only single cells, could be seen in normal control rat ganglia. In contrast, in the normal monkey, ∼20% of dorsal root ganglion neurons, regardless of spinal level, and 10% of trigeminal ganglia neurons expressed mRNA for CCK. CGRP mRNA was expressed at detectable levels in ∼80% of these monkey dorsal root ganglion neurons. In the monkey spinal cord, CCK mRNA was detected in the dorsal horn and in motoneurons, whereas CGRP mRNA was only seen in motoneurons. The present results suggest that CCK peptides can be involved in sensory processing in the dorsal horn of the spinal cord in normal monkeys and in rats after peripheral nerve injury, adding one more possible excitatory peptide to the group of mediators in the dorsal horn.     

Cholecystokinins in rat cerebral cortex: Identification, purification and characterization by immunochemical methods

Cholecystokinins in rat cerebral cortex were studied by radioimmunoassay using an antiserum specific for the COOH-terminus of CCK8. Total concentrations of immunoreactive CCK in cortex were 3–4-fold higher than in jejunum. Rat cerebral CCK was purified by immuno-affinity adsorption to the IgG fraction of CCK antisera conjugated to Sepharose beads, and by gel filtration and ion exchange chromatography. Over 90% of immunoreactive CCK in cortex was accounted for by a factor with the properties of synthetic CCK8, and by a closely related slightly less acidic peptide. In contrast, intestinal CCK consisted of about equal amounts of CCK8-like activity and a larger less acidic immunoreactive component. In both cortex and intestine CCK8-like activity was obtained in substantially higher yield after extracting at neutral pH in boiling water than after extracting in either 0.2 M HCl or 0.5 M acetic acid. However, the larger molecular weight forms of CCK in the intestine were recovered in similar yield by acid and neutral extraction. The principal large form of rat CCK was distinguishable from porcine CCK33 on the basis of both optimum extraction conditions and chromatographic properties. It is suggested that the different distribution of immunoreactive CCK in rat brain and gut can be explained in terms of different biosynthetic processing pathways.     

Expression of the cholecystokinin gene in rat brain during development

The expression of the gene encoding for cholecystokinin (CCK) was studied pre- and postnatally in rat brain with a preproCCK-specific cDNA probe to quantitate mRNA. In addition, a C-terminal-specific radioimmunoassay was used to measure CCK-immunoreactive peptides. Poly(A)+-enriched RNA from rat brain was analyzed for the presence of CCK mRNA by agarose gel electrophoresis, followed by transfer to nitrocellulose and hybridization to a 32P-labeled CCK cDNA probe. An RNA of approximately 700 nucleotides was observed and there were no obvious CCK mRNA differences between samples taken at the different developmental stages. Brain preproCCK mRNA was detectable by embryonic day 14 and increased continuously until postnatal day 14 when it reached maximal concentrations. In young adult rats, levels were slightly decreased. CCK-immunoreactive peptides began to be detected in the samples from embryonic day 21, but marked development was seen only postnatally with a rapid increase occurring during the first 2 weeks after birth. The highest content of the peptide was present in young adult rats.     

Capsaicin depletes CCK-like immunoreactivity detected by immunohistochemistry, but not that measured by radioimmunoassay in rat dorsal spinal cord

In rats treated neonatally with capsaicin there were significant reductions in substance P measured by radioimmunoassay in dorsal spinal cord, spinal ganglia, and coelic ganglia, but concentrations of cholecystokinin octapeptide (CCK8) measured by radioimmunoassay were not decreased. However, immunohistochemical studies using antisera to both substance P and CCK8, respectively, demonstrated decreased immunoreactive material in the dorsal horn of the spinal cord. The nature of the material localized by CCK8 antiserum in immunohistochemistry remains to be resolved.     

Identification of the C-terminal flanking peptide of preprocholecystokinin in rat brain by a novel radioimmunoassay

The C-terminal flanking peptide of preprocholecystokinin (preproCCK) has been identified in extracts of rat brain using a novel radioimmunoassay. There is a single form of immunoreactive material on gel filtration, ion exchange and reversed-phase HPLC. The C-terminal preproCCK immunoreactivity had a similar pattern of distribution to CCK8 in different regions of rat brain. This assay should help in studies of neuronal CCK biosynthesis.     

Assessment of neuromedin B polyclonal antibodies as molecular probes in neural tissue

Five unique, high affinity rabbit polyclonal antibodies against neuromedin B were characterized in a radioimmunoassay in terms of the following parameters: pH and type of buffer, ionic strength, and non-ionic detergents in order to optimize immunoglobulin-peptide interaction; specificity using peptides of the bombesin family, in addition to the tachykinin substance P; and affinity to neuromedin B. Optimum conditions included acidic pH (5.25), high ionic strength (greater than 0.1 M) and absence of non-ionic detergents, which inhibited the assay. Affinities for the 5 antibodies ranged from 10 to 48 fmol neuromedin B with titers from 1:1,000 to 1:10,000 and the sequence-specificity covered the entire peptide; cross-reactivity towards substance P was negligible. As a model tissue, rat spinal cord was homogenized with 5 different extraction solvents, including acetone, methanol, acid and alkaline conditions, and assayed by each polyclonal antiserum; neuromedin B immunoreactivity levels were highest in acid and alkaline extracts and reflected the specificity of the antibody used. Applying these antisera to rat brain extracts, the posterior pituitary gland contained the highest concentration of immunoreactive equivalents of neuromedin B followed by the anterior pituitary, hypothalamus, and hippocampus. The immunoreactive content in the pituitary and hypothalamus, however, depended on the particular antisera used with significant (P less than 0.01) differences existing between them. Further application of these polyclonal antibodies to a spinal cord extract analyzed by isocratic reverse-phase HPLC conditions also revealed differences in their cross-reactivity with the immunoreactive peptides. These antisera may now be used as molecular probes for the determination of extractable immunoreactive neuromedin B from neural tissue and in situ localization by immunohistochemical techniques.     

The distribution of cholecystokinin and vasoactive intestinal peptide in rhesus monkey brain as determined by radioimmunoassay

The concentration of cholecystokinin (CCK) and vasoactive intestinal peptide (VIP) in dissected cortical and subcortical areas of four rhesus monkeys' brains was determined by radioimmunoassay (RIA). Cerebral cortical samples from one human brain are included for comparison. Preliminary data from two baboon brains are described. The results are similar to previous studies on rat (1–7), human (7–12), porcine (12,13), bovine (3) and guinea pig brains (14) and indicate that: 1) both CCK and VIP are widely distributed in cortical and subcortical areas in these species, 2) CCK is generally more abundant than VIP in primate brain, and 3) the distribution of CCK and VIP in the rat brain parallel those in infrahuman primate and human brain.     

Cholecystokinin peptides in the brain and pituitary of the bullfrog Rana catesbiana: distribution and characterization

The distribution of CCK peptides in the bullfrog brain was determined with a CCK radioimmunoassay. Frog brain CCK distribution resembles rat, porcine, and human brain in that CCK concentration is moderate to high in hypothalamus, diencephalon, and medulla (3–18.4 ng /protein) and low in cerebellum (0.6 ng/mg protein). However, unlike all mammalian species examined, the CCK content of frog cerebral cortex, hippocampus and olfactory lobe is quite low (0.03–0.23 ng/mg protein).The elution of CCK-like peptides in frog brain extracts was determined on two HPLC systems. On both systems the bulk of the CCK-like material eluted with CCK8 sulfate and separated from gastrin and other CCK peptides.These data suggest that though the chemical structure of CCK appears to be the same in the brains of frogs and mammals, the distribution of CCK in the brain appears to have shifted during the course of evolution, becoming a cortical, hippocampal, and olfactory system peptide only in more evolved organisms.     

Cholecystokinin peptides in the brain and pituitary of the bullfrog Rana catesbeiana: distribution and characterization

The distribution of CCK peptides in the bullfrog brain was determined with a CCK radioimmunoassay. Frog brain CCK distribution resembles rat porcine and human brain in that CCK concentration is moderate to high in hypothalamus, diencephalon, and medulla (3 18.4 ng/mg protein) and low in cerebellum (0.6 ng/mg protein). However, unlike all mammalian species examined, the CCK content of frog cerebral cortex, hippocampus and olfactory lobe is quite low (0.03 0.23 ng/mg protein). The elution of CCK-like peptides in frog brain extracts was determined on two HPLC systems. On both systems the bulk of the CCK-like material eluted with CCK 8 sulfate and separated from gastrin and other CCK peptides. These data suggest that though the chemical structure of CCK appears to be the same in the brains of frogs and mammals, the distribution of CCK in the brain appears to have shifted during the course of evolution, becoming a cortical, hippocampal, and olfactory system peptide only in more evolved organisms.     

A pilot study of rat brain regional distribution of calcitonin,katacalcin and calcitonin gene-related peptide before and after antipsychotic treatment

In contrast to extensive determinations of calcitonin gene-related peptide (CGRP) in neural tissues, calcitonin and its carboxyl-terminal flanking peptide katacalcin (in human PDN-21) have not been systematically measured by radioimmunoassay (RIA) in discrete brain structures. Using microwave irradiation (MW), a procedure that increases the recovery of neuropeptides, we investigated by radioimmunoassay (RIA) the rat brain regional distribution of CGRP like- immunoreactivity (-LI), calcitonin-LI, and katacalcin-LI. Calcitonin-LI and katacalcin-LI were found in low concentrations in frontal cortex, occipital cortex, striatum and hippocampus. Moreover, a 4-week treatment with antipsychotic drugs altered the concentrations of the calcitonin-gene family peptides in the frontal cortex, occipital cortex, and hippocampus; the magnitude of these changes, however, was only moderate. Lastly, calcitonin-LI and katacalcin-LI baseline concentrations as well as after antipsychotic treatment were highly correlated in the frontal cortex, striatum, and hippocampus. The possible regulatory role of calcitonin gene family peptides in the central nervous system (CNS) needs to be further explored.     

Peptide changes in the parabrachial nucleus following cervical vagal stimulation

Previous studies in our laboratory have shown that the peptides, neurotensin (NT), cholecystokinin (CCK), substance P (SP), somatostatin (SOM), and calcitonin gene-related peptide (CGRP), have a role in modulating ascending visceral sensory information from the nucleus of the solitary tract to the thalamus via a mandatory synapse in the parabrachial nucleus (PB). In this investigation, we examined the changes in the levels of these peptides detected by immunohistochemistry in response to cervical vagal stimulation in the inactin-anesthetized male Wistar rat. Paired control and experimental animals were instrumented to monitor blood pressure and heart rate. The vagus nerve was stimulated for 0.5, 2, or 4 hours, after which time the animals were perfused and the brains processed immunohistochemically for the Fos protein and the peptides NT, CCK, SP, SOM, and CGRP. Vagal stimulation for 1 hour produced large numbers of Fos-positive cells in the external lateral (el), external medial (em), and central lateral (cl) subnuclei of the PB (N = 3). Vagal stimulation produced a reduction in the level of immunolabeling for NT, SOM, and CCK in the el and em subnuclei of the PB. This depletion was present at 0.5 hour and increased in magnitude with the length of vagal stimulation, reaching a maximum after 4 hours. In contrast, the immunolabeling for SP and CGRP increased after 0.5 hour, reaching a maximum after 2 hours of vagal stimulation in the el and em subnuclei of the PB. After 4 hours of vagal stimulation, the immunolabeling for SP and CGRP was depleted in the two PB subnuclei. Thus, the neuropeptides NT, CCK, SP, SOM, and CGRP, which modulate the visceral sensory information in the PB, are influenced somewhat differentially by the level of activity in the vagus nerve. © 1996 Wiley-Liss, Inc.     

Heterogeneity of cholecystokinin/gastrin-like immunoreactivity in the nervous system of the nematode Ascaris suum

A wholemount immunocytochemical method was used for the localization of cholecystokinin (CCK8)-like and gastrin-like immunoreactivity in Ascaris. The patterns of specific neuronal staining given by two antisera and four monoclonal antibodies made against CCK8, and one antiserum made against gastrin were investigated. Preabsorption of these antibodies with CCK8 or gastrin 17 resulted in complete loss of immunoreactivity in almost all of the neurons (two antisera also contained nonspecific antibodies), suggesting that all of the antibodies recognize epitopes, in Ascaris neurons, that include some or all of the C-terminal five amino acids that are identical in CCK8 and gastrin 17. However, the seven different antibodies showed immunoreactivity in different subpopulations of neurons, implying that there are at least seven different species of CCK-like molecules in Ascaris. Fractionation of Ascaris peptide extracts by high performance liquid chromatography (HPLC), monitoring fractions with a CCK8 radioimmunoassay (RIA), also shows heterogeneity of molecules immunologically related to CCK8. © 1996 Wiley-Liss, Inc.     

Sensory neuropeptidergic pattern in tendon, ligament and joint capsule. A study in the rat.

The normal occurrence of sensory neuropeptides in tendons, ligaments and joint capsules in the rat was analyzed by immunohistochemistry and radioimmunoassay (RIA). Nerve fibres immunoreactive to substance P (SP), calcitonin gene-related peptide (CGRP), neurokinin A, galanin and somatostatin were identified in the Achilles tendon as well as the collateral ligaments and joint capsule of the knee. The neuropeptidergic fibres were predominantly found in the epiligament and paratenon. However, SP- and CGRP-positive fibres were also seen in the proper ligament and tendon tissues. RIA showed higher concentrations of SP and CGRP in tendons than in ligaments and capsules. The morphological and quantitative data obtained on sensory neuropeptides in normal tendons, ligaments and joint capsules may be used as a reference for tissue analysis in painful and inflammatory conditions of the locomotor apparatus.     

Trophic effects of cholecystokinin and calcitonin gene-related peptide on ventral spinal cord in culture

We studied trophic effects of cholecystokinin (CCK) and calcitonin gene-related peptide (CGRP) on explanted cultures of ventral spinal cord from 13-14 old day rat embryo. There was a significant neurite promoting effect (NPE) in CCK-treated culture. The neuritic extension of ventral spinal cord exceeds control values 3.5-6.5 times. Otherwise, CGRP and NPE at any concentration. The possible mechanism of trophic effect of CCK on ventral spinal cord was briefly discussed. Our results may contribute to a therapeutic strategy for amyotrophic lateral sclerosis.     

Decreased immunoreactive (IR) calcitonin gene-related peptide correlates with sprouting of IR-peptidergic and serotonergic neuronal processes in spinal cord and brain nuclei from the Wobbler mouse during motoneurons disease

The Wobbler mouse possesses an inherited form of motoneuron disease that expresses itself most dramatically in the forelimbs. Previous immunocytochemical (ICC) studies have shown that neuronal processes containing substance P (SP), thyrotropin releasing hormone (TRH) and serotonin (5-HT) seem to sprout in the ventral horn of the cervical spinal cord taken from the Wobbler mouse. By radioimmunoassay, increased concentrations of spinal SP, TRH, and 5-HT, as well as leucine and methionine enkephalins (LE, ME) have been documented. The present ICC study quantifies the numbers of neuronal processes in the Wobbler cervical spinal cord and brainstem which contain SP, 5-HT, LE, ME and other neuropeptides (cholecystokinin, CCK; neuropeptide Y; galanin; calcitonin gene-related peptide, CGRP). It is proposed that those processes that sprout early in the mononeuron disease (5-HT, LE, ME, CCK and also TRH according to other studies) may be involved in the etiology. In addition, it is hypothesized that the loss of CGRP within the ventral horn may represent the loss of a trophic factor that is important to the survival motoneurons and may influence the increase of fiber densities around the dying motoneurons.