PubMed Health⌕ Search

Biomedical subjects

G J Dockray

Publications and source records attributed to G J Dockray.

At least 163 records · Page 9Linked to original sources
PubMed1984

Immunoreactive Met-enkephalin Arg6 in rat brain, and bovine brain, gut, and adrenal.

Antibodies directed against the Met-enkephalin-related hexapeptide, Met-enk Arg6, have been used in radioimmunoassays in the characterization of material in rat brain, and bovine striatum, colon, and adrenal medulla. Met-enk Lys6 reacted 0.27 relative to Met-enk Arg6, but Leu-enk Arg6 and C-terminal extensions or deletions of Met-enk Arg6 showed less than 0.02 immunoreactivity. In rat brain, the concentration of Met-enk Arg6-like immunoreactivity was less than 20 pmol X g-1 in all regions, but after trypsinization of tissue extracts there were up to 80-fold increases in immunoreactivity as a result of cleavage of C-terminally extended forms. The tryptic product eluted as Met-enk Arg6 on gel filtration. In control extracts of rat brain there were at least three immunoreactive forms of Met-enk Arg6; one eluted in the position of the hexapeptide standard on gel filtration and HPLC while the others had properties of N-terminally extended forms. In bovine striatum and colon the hexapeptide-like material predominated; but in bovine adrenal extracts, there were relatively low concentrations of the hexapeptide and, instead, the dominant immunoreactive forms corresponded to two components that were probably N-terminally extended variants. Trypsin again produced marked increases in immunoreactivity. HPLC studies indicated that Met-enk Arg6Phe7- and Met-enk Arg6Gly7Leu8-like immunoreactive peptides were important substrates in bovine brain for the production of hexapeptide immunoreactivity after trypsin. The differences in the patterns of immunoreactive forms in bovine adrenal, colon, and brain are consistent with tissue variations in the pathways of posttranslational processing of the precursor molecules.

Adrenal Glands↗
PubMed1984

Sensory substance P innervation of the stomach and pancreas. Demonstration of capsaicin-sensitive sensory neurons in the rat by combined immunohistochemistry and retrograde tracing.

The sensory innervation of the stomach and pancreas has been identified by retrograde tracing using the fluorescent dye True Blue (Illing, Gross-Umstadt, Federal Republic of Germany), coupled with the immunohistochemical localization of substance P. Labeled cells were visualized in spinal ganglia, nodose ganglia, celiac ganglion, and dorsal motor nucleus of the vagus after injection of True Blue into both stomach and pancreas. Substance P immunoreactivity was found in 35%-50% of gastric spinal afferent neurons and in approximately 15% of pancreatic spinal afferents. In rats treated at birth with the sensory neurotoxin capsaicin there was a reduction of about 70% in True Blue-labeled cells in the spinal and nodose ganglia, and virtually complete loss of substance P in these ganglia. There was also a marked depletion of substance P-immunoreactive fibers in the pancreas, and in the submucosa of the stomach. The results suggest that the substance P-containing spinal afferents that project to the gastric submucosa are an important component of the gastric sensory innervation.

Animals↗
PubMed1984

N-terminal tryptic fragment of big gastrin. Metabolism and failure to influence gastrin 17-evoked acid secretion in humans.

The metabolism and some biological properties of the N-terminal 1-17 sequence of human big gastrin (G-34) were studied during infusion in 5 human volunteers. Radioimmunoassay of the 1-17 fragment in plasma indicated rapid clearance (t1/2, 2.4 min). In doses of 75-1000 pmol X kg-1 X h-1, 1-17 G-34 did not, however, influence basal acid output or G-17-stimulated acid output. Gel filtration of plasma samples taken during the infusion indicated the presence of the 1-17 fragment of G-34, together with three other immunoreactive species. Two of these correspond to N-terminal G-34 immunoreactive forms previously found in human peripheral circulation. A fourth immunoreactive component that eluted late on Sephadex G50 was identified for the first time. This component also occurred in fasting human plasma, where it was the only detectable form of N-terminal G-34 immunoreactivity; its concentration increased during infusion of 1-17 G-34. The identification of this fragment and its concentrations in human circulation after feeding deserves further study. Because the fragments of 1-17 G-34 do not occur in antral extracts, and are not produced when G-34 or its N-terminal fragments are incubated in plasma in vitro, they are presumed to be generated from the 1-17 sequence by the action of peptidases found on capillary walls. The elucidation of the mechanisms involved is essential for an understanding of the metabolic pathways of gastrin.

Adult↗
PubMed1983

Immunohistochemical studies of FMRF-amide-like immunoreactivity in rat brain.

The anatomical distribution of neuronal perikarya and nerve fibres containing FMRF-amide-like immunoreactivity in the brain, spinal cord and pituitary of the rat has been studied by immunohistochemistry. In animals pretreated with colchicine, the highest concentration of nerve cell bodies occurred in hypothalamic nuclei. Cells were also present in the cortex, striatum, septum, thalamus and in the brainstem. Beaded nerve fibres were abundant in the septum, nucleus of the striae terminalis, hypothalamus, medial regions of the thalamus, the parabrachial nucleus, the ventrolateral medulla, the substantia gelatinosa of the spinal trigeminal nucleus and the dorsal horn of the spinal cord. Fibres were also present in the cortex, striatum, amygdala, pons, ventral spinal cord and the neural lobe of the pituitary. The localization was specific in that preabsorbtion of the antisera with FMRF-amide, but not structurally related molecules such as Met-Enk-Arg6Phe7, APP or BPP, completely abolished the localization. The mammalian counterparts of FMRF-amide may have a neurotransmitter or neuromodulatory role.

Animals↗
PubMed1983

FMRFamide-like immunoreactivity in rat brain: development of a radioimmunoassay and its application in studies of distribution and chromatographic properties.

A radioimmunoassay is described for the molluscan neuropeptide, Phe-Met-Arg-Phe-NH2 (FMRFamide). The antibody used is C-terminal-specific and shows slight but significant (1-2%) cross-reactivity with chicken pancreatic polypeptide (APP). The assay has been used to identify in rat brain extracts a pair of molecules that may represent mammalian counterparts of FMRFamide. Their concentrations were highest in spinal cord and hypothalamus (greater than 10 pmol . g-1) and lowest in cerebellum and striatum (less than 3.5 pmol . g-1). The two immunoreactive peptides were separated on CM ion-exchange chromatography where they appeared to be less basic than FMRFamide. On Sephadex G50 gel filtration one eluted in a similar position of FMRFamide and the other slightly earlier suggesting it may be of higher molecular weight. The rat immunoreactive components do not correspond to previously described neuropeptides or hormones, and may be members of a new group of mammalian neuropeptides with transmitter or modulatory functions.

Animals↗
PubMed1983

Capsaicin-induced depletion of substance P-like immunoreactivity in guinea pig sympathetic ganglia.

The distribution of substance P immunoreactive nerve fibers in guinea pig sympathetic ganglia was studied in normal and capsaicin-treated animals. A marked depletion of substance P-like immunoreactivity was observed in both pre- and paravertebral ganglia after capsaicin treatment. In the inferior mesenteric and pelvic ganglia, however, intensely fluorescent fibers surrounding some of the principal ganglion cells remain after capsaicin treatment. Ligation experiments on the inferior mesenteric ganglion indicate that the capsaicin-insensitive substance P immunoreactive fibers in this ganglion are of lumbar splanchnic origin. Whether or not they represent capsaicin-resistant primary afferent neurons is not known. The enkephalin, vasoactive intestinal polypeptide, cholecystokinin and bombesin immunoreactive fiber networks in the inferior mesenteric ganglion were also studied, and no differences were observed between normal and capsaicin-treated animals.

Animals↗
PubMed1983

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.

Animals↗
PubMed1983

Directional growth of sympathetic nerve fibres in vitro towards enteric smooth muscle and heart from mice with congenital aganglionic colon and their normal littermates.

Neuronotrophic factors in tissues from normal mice and mice with hereditary aganglionic colon (s1/s1) were assayed by examining neurite extension in vitro from sympathetic ganglia (superior cervical and coeliac) towards explants of stomach, atrium and colon in co-culture. Directional growth of neurites from both ganglia towards all 3 target explants was observed. There were no statistically significant differences between normal and s1/s1 ganglia in the capacity to extend neurites, neither were there differences between the target tissues of these mice in ability to promote neurite extension from ganglia. Since it is known that in s1/s1 mice there is impaired migration of neuroblasts along the developing gut, we conclude that the mechanisms determining neurite extension in culture are different to those regulating neuroblast migration and early differentiation. Studies on normal mice revealed that antiserum to nerve growth factor (NGF) blocked the outgrowth of neurites towards atrium, and reduced but did not abolish the outgrowth towards stomach, suggesting that the gut muscle produces a factor trophic for sympathetic neurones which is immunochemically distinguishable from NGF.

Adrenergic Fibers↗
PubMed1983

Origin of peptide-containing fibers in the inferior mesenteric ganglion of the guinea-pig: immunohistochemical studies with antisera to substance P, enkephalin, vasoactive intestinal polypeptide, cholecystokinin and bombesin.

After different denervation procedures the guinea-pig inferior mesenteric ganglion was analysed by immunohistochemistry using antisera to substance P, enkephalin, vasoactive intestinal polypeptide, cholecystokinin and bombesin. The results demonstrate that each of the nerve trunks connected to the ganglion carries specific peptidergic pathways. Thus, the lumbar nerves contain substance P-immunoreactive primary afferent neurons, which to a large extent traverse the ganglion, and enkephalin-immunoreactive preganglionic neurons; the colonic nerves carry vasoactive intestinal polypeptide-, cholecystokinin- and bombesin-immunoreactive fibers from the distal colon to the ganglion; the hypogastric nerves contain vasoactive intestinal polypeptide-positive fibers from the pelvic plexus; and the intermesenteric nerve contains vasoactive intestinal polypeptide, cholecystokinin, substance P and enkephalin from divergent sources. By studying accumulations of peptides in ligated lumbar splanchnic, intermesenteric, hypogastric and colonic nerves the existence of these major peptidergic pathways was confirmed and evidence was obtained for additional, not so prominent, peptidergic projections. The results arae discussed in view of earlier morphological and physiological studies.

Animals↗
PubMed1983

Distribution of enkephalin-related peptides in rat brain: immunohistochemical studies using antisera to met-enkephalin and met-enkephalin Arg6Phe7.

The enkephalin-related heptapeptide, Tyr-Gly-Gly-Phe-Met-Arg-Phe, forms the C-terminus of a biosynthetic precursor that contains both Met-enkephalin and Leu-enkephalin sequences. We have studied the distribution of heptapeptide-like immunoreactivity in rat brain by immunohistochemistry using a C-terminal specific antiserum. The results were compared with those obtained using an antiserum specific for the C-terminus of Met-enkephalin which does not react with C-terminally-extended variants. Both antisera specifically stained cell bodies and fibres in many regions of the rat central nervous system. Colchicine was needed for the demonstration of cell bodies with the Met-enkephalin antiserum, but not for the heptapeptide antiserum. In the nucleus of the solitary tract, in the commissural nucleus, the nucleus raphe obscurus and in the hypothalamus, studies of serial sections and re-staining experiments indicated that the two antisera stained the same cell bodies. However, in the olfactory bulb, the anterior olfactory nucleus, the olfactory tubercle, the nucleus accumbens, caudate-putamen, central nucleus of the amygdala, nucleus interstitialis striae terminalis, pre-lateral mamillary nuclei, ventral hypothalamus, hippocampus, peri-aqueductal grey and the granular layer of the cerebellum, cells were stained by the heptapeptide antiserum but not the Met-enkephalin antiserum. The two antisera revealed similar patterns of staining of nerve fibres in many regions including hypothalamus, central nucleus of the amygdala, lateral septum, thalamus, mid-brain and spinal cord. But in other areas notably, pallidum, caudate-putamen, substantia inominata, nucleus of the solitary tract and commissural nucleus, there were abundant fibres and terminals revealed by the Met-enkephalin antiserum but not by the heptapeptide antiserum. The results are discussed with respect to possible patterns of enkephalin biosynthesis; it is suggested that in some neurones immunoreactive enkephalin precursors terminating in the heptapeptide sequence are processed to produce the heptapeptide which is stored in terminals and is available for release as an endogenous opioid agonist in its own right. In other cases, however, it is suggested that the heptapeptide might be cleaved by removal of -Arg-Phe to yield Met-enkephalin which is the primary opioid product of this class of neurone.

Animals↗
PubMed1983

Sensory substance P-innervation of the urinary bladder: possible site of action of capsaicin in causing urine retention in rats.

In rats treated neonatally with capsaicin there is, in later life, a tendency tendency towards urine retention. Since capsaicin is known to cause irreversible loss of certain primary sensory neurons, notably those containing substance P, we have studied the sensory innervation of the bladder in capsaicin-treated and control rats using retrograde tracing methods and immunohistochemistry; in addition, the motor function of the bladder was assessed in in vitro experiments, using electrical field stimulation. Five days after injection of the fluorescent tracer True Blue into the wall of the bladder, numerous labelled cells were identified in dorsal root ganglia T13, L1, L2, L6, and S1 and smaller numbers of cells were found in T12 and L3. In capsaicin-treated rats the numbers of labelled cells were reduced by over 50% in L1, L6 and S1. In control rats, 10-16% of True Blue labelled cells also contained substance P as demonstrated by indirect immunofluorescence, but in capsaicin-treated rats substance P cells were virtually absent. In in vitro studies, contractions of the detrusor muscle to electrical field stimulation, both before and after atropine, were similar in control and capsaicin-treated rats. We suggest that capsaicin causes urine retention in rats due to an impairment of sensory transmission from the bladder (that could involve substance P) and a consequent failure in the normal micturition reflexes.

Animals↗
PubMed1983

Cholecystokinin- and secretin-induced pancreatic secretion in normal and diabetic rats.

The influence of the endocrine pancreas on exocrine pancreatic function was studied in rats made diabetic by administration of streptozotocin. In normal urethan-anesthetized rats the C-terminal octapeptide of cholecystokinin (CCK-8) stimulated the rate of flow and rates of amylase and trypsinogen release from the pancreas; the proportions of the two enzymes did not change with repeated stimulation. In diabetic rats CCK-8 (0.3-1.2 nmol . kg-1 iv) stimulated significantly greater increases in trypsinogen output and rate of flow compared with normal animals. In contrast, amylase responses to CCK-8 were significantly depressed in diabetic rats. There were no differences between normal and diabetic rats in the flow and total protein responses to exogenous secretin. The present results indicate that the effects of insulin deprivation on relative rates of enzyme synthesis are also expressed in the secretion of the intact pancreas in vivo. These results also raise the possibility that in the normal intact gland there may be nonparallel release of enzymes at different rates of secretion depending on the relative secretory activities of cells in the immediate vicinity of the islets of Langerhans and those distant to the islets.

Animals↗
PubMed1983

Immunohistochemical studies on the gastrointestinal tract using antisera to Met-enkephalin and Met-enkephalin Arg6Phe7.

Antisera specific for the C-terminus of Met-enkephalin and two of its variants isolated from adrenal medulla and brain, namely Met-enk Arg6 and Met-enk Arg6Phe7, have been used in immunohistochemical studies of the gastrointestinal tract in rat, mouse and guinea pig. Met-enk and Met-enk Arg6Phe7-like immunoreactivities were found with similar distribution in nerve cell bodies of the myenteric plexus, and in fibers that were particularly dense in the myenteric plexus and circular smooth muscle. The Met-enk Arg6 antiserum showed weak staining of nerve cells and fibers. In rat and mouse, the antiserum to Met-enk Arg6Phe7, but not those to Met-enk or Met-enk Arg6, also stained numerous endocrine-like cells of the antral mucosa. These were identified as gastrin cells by elution and re-staining experiments with C-terminal gastrin antisera. The rat and mouse gastrin cells might conceivably express the enkephalin gene, but fail to process it to yield Met-enkephalin; alternatively, the Met-enk Arg6Phe7-like immunoreactivity in gastrin cells could be due to a cross-reacting peptide that does not belong to the opioid series.

Animals↗
PubMed1982

Effects of conditioned media on extension of substance P-immunoreactive neurites from cultured mouse sensory ganglia.

Media conditioned by heart or stomach smooth muscle cells stimulated elongation of neurites with substance P-immunoreactivity from explants of mouse dorsal root ganglia in culture, but nerve growth factor (NGF) had no effect. However, NGF is known to be needed for sensory neurone survival; at least two types of factor may therefore be required for the normal development of substance P-containing sensory neurones.

Animals↗
PubMed1982

Coexistence of cholecystokinin- and substance P-like peptides in neurons of the dorsal root ganglia of the rat.

Using the indirect immunohistochemical technique with antisera to cholecystokinin and to substance P, the spinal dorsal horn and dorsal root ganglia of normal and colchicine-treated rats were studied. In the spinal cord a similar distribution of substance P- and cholecystokinin-positive networks in the superficial layers of the dorsal horn was observed. In the dorsal root ganglia several cholecystokinin and substance P immunoreactive cell bodies were seen in colchicine-treated rats. After elution and restaining for substance P, of sections previously stained for cholecystokinin, it was found that all cholecystokinin-positive cells also contained substance P-like immunoreactivity and vice versa.

Animals↗
PubMed1982

Differential distribution in rat basal ganglia of Met-enkephalin- and Met-enkephalin Arg6 Phe7-like peptides revealed by immunohistochemistry.

Antisera to Met-enkephalin and its heptapeptide variant Met-enkephalin Arg6Phe7 were used in immunohistochemistry to study distribution of immunoreactive material in rat basal ganglia. In the pallidum, the Met-enkephalin antiserum, but not the Met-enkephalin Arg6Phe7 antiserum, revealed abundant nerve terminals, whereas in the caudate-putamen the heptapeptide antiserum demonstrated numerous immunoreactive cell bodies that were not shown by the Met-enkephalin antiserum. The differential distribution of immunoreactivity is compatible with distinct physiological roles for the two peptides in basal ganglia.

Animals↗
PubMed1982

Substance P and cholecystokinin-like peptides in Helix neurons and cholecystokinin and serotonin in a giant neuron.

Immunohistochemical procedures revealed that the serotonin-containing cell situated in each metacerebral ganglion of the snail Helix also contains a cholecystokinin-like peptide, but is devoid of substance P. In radioimmunoassays the cholecystokinin-like material showed similarities to the carboxy terminal regions of mammalian cholecystokinin and gastrin. Since much is known about the morphology and synaptic connections of this serotonin neuron, the role of the cholecystokinin-like peptides can now be investigated by neurophysiological methods, thus opening the way to discovering whether a neuron can use more than one transmitter.

Animals↗