Survey of distribution of substance P, vasoactive intestinal polypeptide, cholecystokinin, neurotensin, Met-enkephalin, bombesin and PHI in the spinal cord of cat, dog, sloth and monkey

Neuropeptides and breathing in health and disease

Regulatory neuropeptides control and regulate breathing in physiological and pathophysiological conditions. While they have been identified in the neurons of major respiratory areas, they can be active not only at the central level, but also at the periphery via chemoreceptors, vagal afferents, or locally within lungs and airways. Some neuropeptides, such as leptin or substance P, are respiratory stimulants; others, such as neurotensin, produce variable effects on respiration depending on the site of application. Some neuropeptides have been implicated in pathological states, such as obstructive sleep apnea or asthma. This article provides a concise review of the possible role and functions of several selected neuropeptides in the process of breathing in health and disease and in lung pathologies.

Expression profile of flotillin-2 and its pathophysiological role after spinal cord injury

Some receptors that block axonal regeneration or promote cell death after spinal cord injury (SCI) are localized in membrane rafts. Flotillin-2 (Flot-2) is an essential protein associated with the formation of these domains and the clustering of membranal proteins, which may have signaling activities. Our hypothesis is that trauma will change Flot-2 expression and interference of this lipid raft marker will promote functional locomotor recovery after SCI. Analyses were conducted to determine the spatiotemporal profile of Flot-2 expression in adult rats after SCI, using the MASCIS impactor device. Immunoblots showed that SCI produced a significant decrease in the level of Flot-2 at 2 days post-injury (DPI) that increased until 28 DPI. Confocal microscopy revealed Flot-2 expression in neurons, reactive astrocytes and oligodendrocytes specifically associated to myelin structures near or close to the axons of the cord. In the open field test and grid walking assays, to monitor locomotor recovery of injured rats infused intrathecally with Flot-2 antisense oligonucleotides for 28 days showed significant behavioral improvement at 14, 21 and 28 DPI. These findings suggest that Flot-2 has a role in the nonpermissive environment that blocks locomotor recovery after SCI by clustering unfavorable proteins in membrane rafts.

Neurotensin receptor 1 immunoreactivity in the peripheral ganglia and carotid body

In the present study we investigated, through immunohistochemistry, the presence and location of neurotensin receptor 1 (NTR1) in the peripheral ganglia and carotid body of 16 humans and 5 rats. In both humans and rats, NTR1 immunostained ganglion cells were found in superior cervical ganglia (57.4+/-11.6% and 72.4+/-11.4%, respectively, p0.05), enteric ganglia (51.9+/-10.4% and 64.6+/-6.1, p<0.05), sensory ganglia (69.2+/-10.7% and 73.0+/-13.1%, p>0.05) and parasympathetic ganglia (52.1+/-14.1% and 59.4+/-14.0%, p>0.05), supporting a modulatory role for NT in these ganglia. Positivity was also detected in 45.6+/-9.2% and 50.8+/-6.8% of human and rat type I glomic cells, respectively, whereas type II cells were negative. Our findings suggest that NT produced by type I cells acts in an autocrine or paracrine way on the same cell type, playing a modulatory role on chemoception.

Kainate receptors are primarily postsynaptic to SP-containing axon terminals in the trigeminal dorsal horn

Kainate receptors (KARs) are involved in the modulation and transmission of nociceptive information from peripheral afferents to neurons in the spinal cord and trigeminal dorsal horns. KARs are found at both pre- and postsynaptic sites in the dorsal horn. We hypothesized that KARs and Substance P (SP), a modulatory neuropeptide that is used as a marker of nociceptive afferents, have a complex interactive relationship. To determine the cellular relationship and connectivity between KARs and SP afferents, we used electron microscopic dual immunocytochemical analysis to examine the ultrastructural localization of KAR subunits GluR5, 6 and 7 (GluR5,6,7) in relation to SP within laminae I and II in the rat trigeminal dorsal horn. KARs were distributed both postsynaptically in dendrites and somata (51% of GluR5,6,7 immunoreactive (-ir) profiles) and presynaptically in axons and axon terminals (45%). We also found GluR5,6,7-ir glial profiles (5%). The majority of SP-ir profiles were presynaptic axons and axon terminals. SP-ir dendritic profiles were rare, yet 23% contained GluR5,6,7 immunoreactivity. GluR5,6,7 and SP were also colocalized at presynaptic sites (18% of GluR5,6,7-ir axons and axon terminals contained SP; while 11% of SP-ir axons and axon terminals contained GluR5,6,7). The most common interaction between KARs and SP we observed was GluR5,6,7-ir dendrites contacted by SP-ir axon terminals; 54% of the dendritic targets of SP-ir axon terminals were GluR5,6,7-ir. These results provide anatomical evidence that KARs primarily mediate nociceptive transmission postsynaptic to SP-containing afferents and may also modulate the presynaptic release of SP and glutamate in trigeminal dorsal horn.

Comparative analysis of the chemical neuroanatomy of the mammalian trigeminal ganglion and mesencephalic trigeminal nucleus

A characteristic peculiarity of the trigeminal sensory system is the presence of two distinct populations of primary afferent neurons. Most of their cell bodies are located in the trigeminal ganglion (TG) but part of them lie in the mesencephalic trigeminal nucleus (MTN). This review compares the neurochemical content of central versus peripheral trigeminal primary afferent neurons. In the TG, two subpopulations of primary sensory neurons, containing immunoreactive (IR) material, are identified: a number of glutamate (Glu)-, substance P (SP)-, neurokinin A (NKA)-, calcitonin gene-related peptide (CGRP)-, cholecystokinin (CCK)-, somatostatin (SOM)-, vasoactive intestinal polypeptide (VIP)- and galanin (GAL)-IR ganglion cells with small and medium-sized somata, and relatively less numerous larger-sized neuropeptide Y (NPY)- and peptide 19 (PEP 19)-IR trigeminal neurons. In addition, many nitric oxide synthase (NOS)- and parvalbumin (PV)-IR cells of all sizes as well as fewer, mostly large, calbindin D-28k (CB)-containing neurons are seen. The majority of the large ganglion cells are surrounded by SP-, CGRP-, SOM-, CCK-, VIP-, NOS- and serotonin (SER)-IR perisomatic networks. In the MTN, the main subpopulation of large-sized neurons display Glu-immunoreactivity. Additionally, numerous large MTN neurons exhibit PV- and CB-immunostaining. On the other hand, certain small MTN neurons, most likely interneurons, are found to be GABAergic. Furthermore, NOS-containing neurons can be detected in the caudal and the mesencephalic-pontine junction portions of the nucleus. Conversely, no immunoreactivity to any of the examined neuropeptides is observed in the cell bodies of MTN neurons but these are encircled by peptidergic, catecholaminergic, serotonergic and nitrergic perineuronal arborizations in a basket-like manner. Such a discrepancy in the neurochemical features suggests that the differently fated embryonic migration, synaptogenesis, and peripheral and central target field innervation can possibly affect the individual neurochemical phenotypes of trigeminal primary afferent neurons.

Colonic motility in chronic ulcerative proctosigmoiditis and the effects of nicotine on colonic motility in patients and healthy subjects

BACKGROUND

Nicotine decreases diarrhoea and pain in ulcerative colitis without reducing inflammation.

AIMS

(i) To evaluate the effect of ulcerative proctosigmoiditis on motor functions of an uninflamed segment of descending colon; and (ii) to assess nicotine's effects on colonic motor functions in patients and healthy subjects.

METHODS

In healthy subjects (n=30) and patients with ulcerative colitis (13; 11 active, two quiescent colitis), we studied the effects of intravenous nicotine on colonic transit of solid residue by scintigraphy (healthy subjects) and on colonic motility in healthy subjects and 11 patients.

RESULTS

In ulcerative colitis, fasting colonic motility was increased, whereas motor response to a meal was significantly reduced; compliance was unchanged. In healthy subjects, high-dose nicotine induced transient high amplitude propagated contractions and relaxation of the descending colon followed by decreased phasic contractions. This dose also accelerated colonic transit. Low-dose nicotine (mimicking a transdermal nicotine patch) reduced colonic compliance in healthy subjects, but did not affect motor function in ulcerative colitis.

CONCLUSIONS

Ulcerative proctosigmoiditis increases fasting colonic motility and reduces tone response to a meal in the descending colon without affecting colonic compliance, suggesting changes in physiological responses but not intrinsic wall properties. Nicotine has dose-dependent effects on colonic motor activity in healthy subjects.

An update on the physiology of two- and three-toed sloths

Physiological and pharmacological research undertaken on sloths during the past 30 years is comprehensively reviewed. This includes the numerous studies carried out upon the respiratory and cardiovascular systems, anesthesia, blood chemistry, neuromuscular responses, the brain and spinal cord, vision, sleeping and waking, water balance and kidney function and reproduction. Similarities and differences between the physiology of sloths and that of other mammals are discussed in detail.

VIP and PACAP: very important in pain?

Neuropathic pain arising from direct trauma to, or compression injury of, peripheral nerves is a common clinical problem. It is characterized by the development of abnormal pain states (spontaneous pain, hyperalgesia, allodynia), which can persist long after the initial injury has resolved. The underlying mechanisms are poorly understood and, as a consequence, treatment is often unsatisfactory. Some of the main contributing factors are thought to be the morphological and phenotypic changes that occur centrally, including alterations in the expression of neurotransmitters and their associated receptors, both in the dorsal root ganglia and in the spinal dorsal horn. This article focuses on the functional role of the two structurally related peptides VIP and PACAP within the spinal cord, and their possible contribution to the altered transmission of sensory information in neuropathic conditions.

Effects of calcitonin gene-related peptide-(8-37) on withdrawal responses in rats with inflammation

The present study was performed to explore the effect of subcutaneous injection of carrageenan into the rat plantar region on hindpaw edema formation and the latency of hindpaw withdrawal to presumed nociceptive stimulation. Subcutaneous injection of carrageenan into the left hindpaw induced a significant increase in the volume of the left hindpaw, leaving the right side unaffected. In addition, we found a bilateral decrease in hindpaw withdrawal latency to heat and mechanical, but not to cold stimulation. The decreased bilateral hindpaw withdrawal latency to heat stimulation lasted for 14 days after carrageenan injection. The decreased bilateral hindpaw withdrawal latency to mechanical stimulation lasted for 2 days after the injection, then reversed and increased from day 3 to 14. Intrathecal injection of either 10 nmol of calcitonin gene-related peptide 8-37 or 26.6 nmol of morphine induced significant bilateral increases in hindpaw withdrawal latency, which were more pronounced with the morphine. The results show that experimentally induced unilateral hindpaw inflammation induces a bilateral decrease in hindpaw withdrawal latencies to presumed nociceptive stimulation while the sensory systems for heat and mechanical stimulation were differently affected after carrageenan injection.

Effect of cerebroventricular perfusion of bombesin on gastrointestinal myoelectric activity

The effect of intracerebroventricular (i.c.v.) perfusion of bombesin (BBS) on the interdigestive migrating myoelectric complex (MMC) activity was examined in conscious dogs with electrodes implanted on the stomach and small intestine. Cannulas and a catheter were chronically positioned in the lateral and fourth cerebral ventricles, respectively. i.c.v. perfusion of BBS, which failed to increase plasma BBS levels, replaced phase I activity in the stomach and duodenum by intense irregular spike activity and decreased the occurrence rate of MMCs, whereas intravenous infusion of BBS evoked phase II-like activity, mainly in the jejunum and ileum, and suppressed phase III activity. These data suggest that the effect of i.c.v. administration of BBS was mediated by direct activation of central brain structures. During i.c.v. perfusion of BBS, cycling in plasma levels of motilin persisted even when phase III activity was absent and plasma levels of epinephrine rose significantly. Epinephrine infusion, however, did not affect myoelectric gastrointestinal activity except for prolonging phase II. Thus it is unlikely that the central action of BBS is exerted by motilin or epinephrine.

Effects of endotracheal intubation on airway neuropeptide content, arterial oxygenation and lung volumes in anaesthetized rats

BACKGROUND

General anaesthesia affects lung volume and pulmonary gas exchange. What role is played by mechanical stimulation by the endotracheal tube?

METHODS

We investigated the effects of intubation on arterial oxygenation and lung volume in rats.

RESULTS

Endotracheal intubation caused an increase in PA-aO2 and volume of trapped gas in the lung. This was accompanied by a reduction in neuropeptides and calcitonin gene-related peptide (CGRP) in trachea, bronchi and lung, and in vasoactive intestinal peptide (VIP) in the trachea. The increase in PA-aO2 and volume of trapped gas due to intubation was not altered in the animals given capsaicin, in which neuropeptide levels were reduced.

CONCLUSIONS

These data suggest that the decrease in CGRP and VIP content in the airway tissues may be one of the consequences, but not the cause, of impaired gas exchange by endotracheal intubation. The increase in volume of trapped gas in the lung is apparently not mediated by activation of capsaicin-sensitive sensory nerves.

Effects of glucagon on postprandial carbohydrate metabolism in nondiabetic humans

The present experiments sought to determine whether glucagon concentrations mimicking those observed in people with diabetes mellitus alter postprandial carbohydrate metabolism in nondiabetic humans. We measured the gastric emptying of solids and liquids, the systemic rate of appearance of ingested glucose, and endogenous glucose production either when postprandial suppression of glucagon was prevented by infusing glucagon at a rate of 0.65 ng/kg/min, when postprandial glucagon concentrations were elevated by infusing glucagon at a rate of 3.0 ng/kg/min, or when postprandial suppression of glucagon was permitted by infusion of saline. Despite marked differences in glucagon concentrations, postprandial glucose and insulin concentrations did not differ on any occasion. Although gastric emptying of liquids and solids was comparable on all three occasions, the high-dose, but not the low-dose, glucagon infusion caused a slight delay in the systemic appearance of ingested glucose and a significant decrease (P < .01) in postprandial D-xylose concentrations, suggesting a delay in carbohydrate absorption. However, this was offset by an increase (P < .05) in endogenous glucose production, resulting in no difference in postprandial glucose appearance. We conclude that in the absence of insulin deficiency, neither a lack of suppression of glucagon nor an elevation of glucagon to levels encountered in uncontrolled diabetes mellitus cause postprandial hyperglycemia in nondiabetic humans.

Intrathecal adenosine analog administration reduces substance P in cerebrospinal fluid along with behavioral effects that suggest antinociception in rats

Adenosine and adenosine analogs induce analgesia in humans and presumed antinociception in animal models when administered both systemically and intrathecally. In the present investigation in rats, we studied the effects of intrathecally administered adenosine analogs, with or without systemic coadministration of an adenosine antagonist (theophylline), on substance P (SP) and calcitonin gene-related peptide (CGRP) concentrations in cerebrospinal fluid (CSF). In parallel, nociceptive reflex testing (tail immersion latency) and motor function were evaluated. The potent unselective adenosine receptor agonist N-ethylcarboxamide-adenosine (NECA) and the relatively adenosine A1 receptor selective agonist R-phenyl-isopropyl-adenosine (R-PIA) both reduced SP-like immunoreactivity (-LI) by 50%, whereas CGRP-LI remained unchanged. There was a dose-dependent increase in tail immersion latency. This effect was present without motor impairment when R-PIA was administered in doses up to 5 nmol. R-PIA (10-100 nmol), as well as 1-100 nmol of the unselective agonist NECA, produced dose-dependent motor impairment. The reduction of SP-LI as well as the behavioral effects were reversed by theophylline. We conclude that SP reduction in CSF, which possibly reflects reduced SP turnover after adenosine receptor stimulation, provides an additional possible mechanism of action for the analgesic effects of adenosine.

IMPLICATIONS

We studied the interactions between the known pain mediator substance P and substances with effects similar to the endogenous pain modulator adenosine in rats. The results suggest that the pain-reducing effect of adenosine is, at least partly, due to a reduction of substance P in cerebrospinal fluid.

Evidence for roles of vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase activating polypeptide (PACAP) receptors in modulating the responses of rat dorsal horn neurons to sensory inputs

The extracellularly recorded electrophysiological activity of single multireceptive dorsal horn neurons was markedly increased by ionophoretic administration of vasoactive intestinal polypeptide (VIP) or pituitary adenylate cyclase activating polypeptide (PACAP)-38. Some cells responded selectively to PACAP-38 (suggesting mediation by a PACAP receptor), whereas others responded to both VIP and PACAP-38 (suggesting a VIP1 and/or VIP2 receptor). Most non-nociceptive cells were unaffected by PACAP-38 and all were unaffected by VIP. The selectivity of VIP/PACAP receptor antagonists was established on cloned rat VIP1, VIP2 and PACAP receptors in vitro before their utilization to indicate the likely involvement of VIP1, and possibly PACAP receptors, in VIP- and PACAP-38-mediated responses of dorsal horn neurons. The VIP/PACAP receptor antagonists inhibited responses of multireceptive cells to sustained innocuous (brush) and noxious (mustard oil) stimuli, with a selectivity suggesting the involvement of VIP1 and PACAP receptors, although the participation by VIP2 receptors cannot be excluded. These data implicate both VIP and PACAP in regulating the basal responsiveness of multireceptive dorsal horn neurons to sensory stimuli.

Enkephalinergic and dynorphinergic neurons in the spinal cord and dorsal root ganglia of the polyarthritic rat - in vivo release and cDNA hybridization studies

Complex and contradictory data have been reported regarding the changes in spinal opioidergic systems associated with chronic inflammatory pain in the rat. In an attempt to solve these discrepancies, the in vivo release of met-enkephalin and dynorphin and the expression of the corresponding propeptide genes were investigated at the spinal level in arthritic rats and paired controls. A dramatic increase in the concentration of prodynorphin mRNA (+300-550%) and a less pronounced elevation of that of dynorphin-like material (+40-50%) were found in the dorsal part of cervical and lumbar segments of the spinal cord in rats rendered arthritic by an intradermal injection of Freund's adjuvant four weeks prior to these measurements. In addition, the spinal release of dynorphin-like material (assessed through an intrathecal perfusion procedure in halothane-anaesthetized animals) was approximately twice as high in arthritic rats as in controls. In spite of significant elevations in the levels of both met-enkephalin (+30-70%) and proenkephalin A mRNA (+40-50%) in the dorsal part of cervical and lumbar segments, the spinal release of met-enkephalin-like material was decreased (-50%) in arthritic rats as compared to paired controls. Proenkephalin A mRNA (but not prodynorphin mRNA) could be measured in dorsal root ganglia, and its levels were dramatically reduced in ganglia at the lumbar segments in arthritic rats. Such parallel reductions in the spinal release of met-enkephalin-like material and the levels of proenkephalin A mRNA in dorsal root ganglia of arthritic rats support the idea that the activity of primary afferent enkephalinergic fibres decreases markedly during chronic inflammatory pain.

Clinical spectrum of hyperglucagonemia associated with malignant neuroendocrine tumors

OBJECTIVE

To review the clinical features associated with hyperglucagonemia in malignant neuroendocrine tumors.

MATERIAL AND METHODS

We retrospectively reviewed the medical records of patients with hyperglucagonemia encountered at our institution from Oct. 17, 1988, through February 1993 who had a fasting serum glucagon level of at least 120 pg/mL (twice the normal value). The 71 study patients also had no evidence of a secondary cause of hyperglucagonemia and had pathologic confirmation of a neuroendocrine tumor.

RESULTS

The study group consisted of 46 men and 25 women with a median age of 57 years. Two patients had multiple endocrine neoplasia. Forty-nine patients had biochemically polyfunctional tumors, and 22 had hyperglucagonemia only. The most common initial symptoms were weight loss, abdominal pain, diarrhea, nausea, peptic ulcer disease, diabetes, and necrolytic migratory erythema (NME). Diabetes eventually developed in 25 patients and was associated with NME in 11. The highest median serum glucagon values occurred in patients with the glucagonoma syndrome or insulinomas, and the lowest median values were in those with carcinoid syndrome, Zollinger-Ellison syndrome, or diabetes without NME. Fasting glucagon and glucose measurements were not correlated. The most common hormonal syndromes were the Zollinger-Ellison syndrome and the glucagonoma syndrome. All the neuroendocrine tumors were malignant. Several methods of treatment, including surgical debulking, chemotherapy, somatostatin, and hepatic artery embolization, were used. Death occurred in 29 patients at a median of 2.79 years after diagnosis; 42 patients were alive at a median of 2.86 years after diagnosis.

CONCLUSION

A mild degree of hyperglucagonemia can commonly be associated with multifunctional neuroendocrine tumors. The glucagonoma syndrome occurs in a few patients with malignant neuroendocrine tumors and hyperglucagonemia and is associated with very high serum glucagon levels. The correlation between serum glucagon levels and the development of diabetes is limited, and other factors such as insulin may be more important than hyperglucagonemia in the development of diabetes.

Neuropeptide Y release and contractile properties: differences between canine veins and arteries

During intense sympathetic activation, as occurs during hemorrhage, veins constrict to a greater degree than do arteries. This study determined if differences in the amounts or actions of the sympathetic cotransmitter neuropeptide Y released from perivascular nerves could contribute to these differences. Strips of canine mesenteric and popliteal arteries and of saphenous and portal veins were superfused, and the releases of noradrenaline and neuropeptide Y evoked by transmural stimulation were assessed. Both compounds were released in greater amounts in the veins than in the arteries. In other experiments rings of each vessel were mounted in organ chambers for isometric-tension recording. Neuropeptide Y (up to 10(-4) M) did not contract any vessel; however, at 3 x 10(-7) M it shifted the frequency-response and concentration-response curves to noradrenaline in the arteries only. In the veins neuropeptide Y had no postsynaptic effect on strong contractions. These results suggest that neuropeptide Y functions locally to affect vasoconstriction of the arteries studied, and may have a different role in the veins. Further, processes involving neuropeptide Y do not appear to account for the differences in responsiveness of these arteries as compared to the veins during intense sympathetic stimulation.

Peptidergic innervation of the mesencephalic trigeminal nucleus in the cat

BACKGROUND

The trigeminal processing of proprioceptive information is unique and very little is known about the neurochemical organization of trigeminal primary afferent neurons which mediate the sensory aspects of proprioception. In studies using immunocytochemicalretrograde tracing techniques, some classical neurotramsitters mediating the afferent modulation of the mesencephalic trigeminal nucleus (MTN) have been investigated. This paper summarizes our current understanding of the peptidergic innervation of the cat MTN.

METHODS

The distribution of immunoreactive substances was studied using specific antisera against 11 major neuropeptides. Light and electron microscopic peroxidase-antiperoxidase immunocytochemical staining techniques in colchicine-treated animals were used to clarify the distribution of peptide-identified fibers related to the MTN.

RESULTS

Immunoreactivity to any of the tested neuropeptides could not be detected in the MTN cell bodies. Numerous fibers containing various peptides such as substance P, bombesin, enkephalins, cholecystokinin, vasoactive intestinal polypeptide, vasopressin, and neuropeptide Y were present in the nucleus, however. These thin positive fibers covered the neuronal surface of the MTN cell bodies and some of the immunoreactive varicosities appeared to be in close proximity to profiles of MTN neurons. Electron microscopic observations revealed that perisomatic fibers were in direct apposition to perikarya of unstained large cells and some of them made synaptic contacts with their cell bodies and dendrites.

CONCLUSIONS

The present results demonstrate that the MTN neurons receive dense basket-like innervation from peptidergic neurons on somata and processes and have supported earlier evidence that the MTN of the cat is under influence of peptidergic input. Results of this study provide further evidence that the neuropeptides examined may play an important role in the integration and transmission of trigeminal proprioceptive information. Most likely they may co-exist with a classical but hitherto unknown neurotransmitter(s), that is unique for this region and whose release can be modulated by peptides.

The glucagonoma syndrome. Clinical and pathologic features in 21 patients

The glucagonoma syndrome is a rare disorder characterized by weight loss, necrolytic migratory erythema (NME), diabetes, stomatitis, and diarrhea. We identified 21 patients with the glucagonoma syndrome evaluated at the Mayo Clinic from 1975 to 1991. Although NME and diabetes help identify patients with glucagonomas, other manifestations of malignant disease often lead to the diagnosis. If the diagnosis is made after the tumor is metastatic, the potential for cure is limited. The most common presenting symptoms of the glucagonoma syndrome were weight loss (71%), NME (67%), diabetes mellitus (38%), cheilosis or stomatitis (29%), and diarrhea (29%). Although only 8 of the 21 patients had diabetes at presentation, diabetes eventually developed in 16 patients, 75% of whom required insulin therapy. Symptoms other than NME or diabetes mellitus led to the diagnosis of an islet cell tumor in 7 patients. The combination of NME and diabetes mellitus led to a more rapid diagnosis (7 months) than either symptom alone (4 years). Ten patients had diabetes mellitus before the onset of NME. No patients had NME clearly preceding diabetes mellitus. Increased levels of secondary hormones, such as gastrin (4 patients), vasoactive intestinal peptide (1 patient), serotonin (5 patients), insulin (6 patients, clinically significant in 1 only), human pancreatic polypeptide (2 patients), calcitonin (2 patients) and adrenocorticotropic hormone (2 patients), contributed to clinical symptoms leading to the diagnosis of an islet cell tumor before the onset of the full glucagonoma syndrome in 2 patients. All patients had metastatic disease at presentation. Surgical debulking, chemotherapy, somatostatin, and hepatic artery embolization offered palliation of NME, diabetes, weight loss, and diarrhea. Despite the malignant potential of the glucagonomas, only 9 of 21 patients had tumor-related deaths, occurring an average of 4.91 years after diagnosis. Twelve patients were still alive, with an average age follow-up of 3.67 years.

Release of calcitonin gene-related peptide in guinea pig inferior mesenteric ganglion

Neurons of the guinea pig IMG are surrounded by nerve fibers containing CGRP-like immunoreactivity (LI). The purpose of this study was to determine whether colonic distension releases CGRP-LI in the IMG and whether opioid peptides and neurotensin(8-13) [NT(8-13)] modulate its release. Colonic distension released CGRP-LI. Methionine-enkephalin acted through mu and/or delta receptors to block release. NT(8-13) had no effect on release of CGRP-LI. Capsaicin pretreatment reduced the content of CGRP-LI in the IMG by 37%. Colonic distension did not release CGRP-LI from capsaicin-insensitive fibers. The data suggest that colonic distension releases CGRP-LI material from capsaicin-sensitive nerves and that enkephalins modulate release of CGRP-LI.

Intraileal carbohydrate regulates canine postprandial pancreaticobiliary secretion and upper gut motility

BACKGROUND & AIMS

The effect of nutrients in the distal small intestine or colon on postprandial upper gut function is incompletely understood. The aim of this study was to determine if carbohydrate in the ileum or proximal colon of dogs affects postprandial pancreaticobiliary secretion, gastrointestinal transit, and circulating concentrations of certain gastrointestinal regulatory peptides.

METHODS

Seven dogs were prepared with permanent infusion and aspiration catheters in the duodenum and ileum and an infusion catheter in the cecum. Coincident with eating a meal containing liquid and solid markers, ileal or colonic (n = 5 dogs for each) infusion were begun of isosmolar 0.9% NaCl or carbohydrate in a 3:1 ratio of starch to glucose. Pancreatic enzyme output, bile acid delivery, gastrointestinal polypeptide, and plasma concentrations of pancreatic polypeptide, neurotensin, and peptide YY were measured for 6 hours postprandially.

RESULTS

Carbohydrate infusion in the ileum, but not in the proximal colon, increased amylase secretion and plasma peptide YY, slowed gastric emptying of liquids and solids, slowed small intestinal transit, and decreased bile acid delivery into the duodenum (P < 0.05 in each).

CONCLUSIONS

Carbohydrate in the ileum regulates postprandial exocrine pancreatic enzyme secretion and other postprandial upper gut functions. Peptide YY may play a role in this regulation.

Quantitative autoradiographic localization of [125I-Tyr8]bradykinin receptor binding sites in the rat spinal cord: effects of neonatal capsaicin, noradrenergic deafferentation, dorsal rhizotomy and peripheral axotomy

In vitro receptor autoradiography was used to localize, quantify and characterize [125I-Tyr8]bradykinin binding sites in all major spinal cord segments of normal rats and animals subjected to various chemical treatments and surgical lesions. [125I-Tyr8]bradykinin specific binding sites were predominantly located to superficial laminae of the rat dorsal horn, with the substantia gelatinosa showing the highest density of labelling (values ranging from 3.1 fmol/mg tissue in cervical to 4.5 fmol/mg tissue in lumbar segments). A moderate density (1.8-3.0 fmol/mg tissue) of specific binding was observed in lamina III, whereas in other areas, i.e. laminae I and IV-X, lower amounts of labelling were detected. Within the superficial laminae of the dorsal horn, [125I-Tyr8]bradykinin binding was largely distributed over the neurophil with some perikarya showing concentrations of labelling. In contrast, the ventral horn showed a rather homogeneous distribution of [125I-Tyr8]bradykinin binding over the neuropil, with silver grain alignments surrounding motoneuron perikaryas and proximal processes. Bradykinin, [Tyr8]bradykinin and B2 receptor antagonists (D-Arg[Hyp3,Thi5,D-Tic7,Oic8]bradykinin (Hoe 140), D-Arg[Tyr3,D-Phe7,Leu8]bradykinin, D-Arg[Hyp3, Leu8]bradykinin, D-Arg[Hyp2, Thi5,8,-Phe7]bradykinin D-Arg[Hyp3, D-Phe7, Leu8]bradykinin, Tyr0, D-Arg[Hyp3, D-Phe7, Leu8]bradykinin inhibited [125I-Tyr8]-bradykinin binding with very high subnanomolar affinities, while the B1 receptor agonist (Tyr0,des-Arg10-kallidin) and antagonist ([Leu8]-des-Arg9-bradykinin) did not significantly affect [125I-Tyr8]bradykinin binding at up to micromolar concentrations. Two weeks after unilateral lumbar dorsal rhizotomy (L1-L6) or peripheral lesions of the sciatic nerve, significant decreases ( +/- 50%) in [125I-Tyr8]bradykinin binding sites were found in ipsilateral laminae I-III of lumbar spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of accelerated gastric emptying of liquids and hyperglycemia in patients with type II diabetes mellitus

BACKGROUND & AIMS

The roles of hyperglycemia in diabetic gastroparesis and gastric delivery in postprandial hyperglycemia of diabetic patients are unclear. The aims of this study were to assess gastric emptying and its relation to postprandial glucose metabolism in patients with asymptomatic non-insulin-dependent diabetes mellitus (NIDDM) and no autonomic neuropathy and to identify motor mechanisms responsible for any accelerated gastric emptying.

METHODS

Autonomic function, gastric emptying, postprandial glucose metabolism, and hormone levels (glucagon, insulin, cholecystokinin, glucose-dependent insulinotropic polypeptide, neurotensin, and peptide YY) were assessed in healthy volunteers and patients with NIDDM. In a second study, gastric tone and motility were measured in patients with accelerated gastric emptying and in controls.

RESULTS

Gastric emptying of solids did not differ in the two groups, but liquids emptied faster in patients with NIDDM (P < 0.02). The rate of entry of ingested glucose into the systemic circulation was similar, but higher postprandial glucagon and lower insulin concentrations led to greater (P < 0.01) postprandial hepatic glucose release. Levels of other enteropeptides, gastric accommodation, and antral motility were similar, but patients with NIDDM had greater proximal gastric phasic contractions than controls (P < 0.05).

CONCLUSIONS

Excessive hepatic glucose release, not rapid entry of ingested glucose, is the primary cause of postprandial hyperglycemia in patients with NIDDM. Accelerated gastric emptying in patients with nonneuropathic NIDDM is associated with increased proximal stomach phasic contractions.

Effects of intracerebral injections of VIP on jejunal alanine absorption and gastric acid secretion in rats

The effects of intracerebral injections of VIP on jejunal alanine absorption and gastric acid secretion, and its association with vagal outflow were examined in Sprague-Dawley rats. Intracerebroventricular injection of VIP (2 ng) decreased significantly (P < 0.05) alanine absorption across the jejunum, whereas similar injections in vagotomized rats did not show further decrease in absorption beyond that noticed by vagotomy only. Moreover, VIP injected in the Nucleus Tractus Solitarius-Dorsal Motor Nucleus (NTS-DMN) complex (1 ng) produced also a significant inhibition of Ala absorption which was reduced but remained significant (P < 0.05) after vagotomy. Water movement was not affected by VIP injection in the lateral ventricle, while VIP injections in the NTS-DMN inhibited significantly (P < 0.05) jejunal water absorption by 10-12%. Vagotomy increased water absorption by 15-20% above control (P < 0.05) which was not altered by injecting VIP in the NTS-DMN complex. On the other hand, VIP injection in the NTS-DMN produced a 25.7% increase in gastric acid output in the first hour of the experiment followed by a non-significant decrease (P > 0.05) in the second hour. Same injections done in vagotomized animals produced similar effects to those elicited by vagotomy only. It can be suggested that NTS-DMN complex could be a site of action of VIP since injection of VIP in it produced a more pronounced inhibitory effect on water and Ala absorption than that produced by VIP injection in the LV. These effects were reduced or abolished by vagotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective association of nerve fibres immunoreactive for substance P or bombesin with putative cholinergic neurons of the male rat major pelvic ganglion

The male rat major pelvic ganglion contains both sympathetic and parasympathetic neurons that supply the lower urinary and digestive tracts, and the reproductive organs. The aim of this study was to describe the distribution and identify potential targets of sensory and intestinofugal axons in this ganglion. Two putative markers of these projections were chosen, substance P for primary sensory axons and bombesin for myenteric intestinofugal projections. Varicose substance P-immunoreactive axons were associated only with non-noradrenergic (putative cholinergic) somata, and most commonly with those that contained vasoactive intestinal peptide. Immunoreactivity for substance P was also present in a small group of non-noradrenergic somata, many of which were immunoreactive for enkephalins, neuropeptide Y or vasoactive intestinal peptide. Bombesin immunoreactivity was found only in preterminal and terminal (varicose) axons, the latter of which were exclusively associated with non-noradrenergic somata that contain neuropeptide Y-immunoreactivity. Some varicose axons containing either substance P- or bombesin-immunoreactivity were intermingled with clumps of small, intensely fluorescent cells. These studies indicate that substance P- and bombesin-immunoreactive axons are likely to connect with numerically small, but discrete, populations of pelvic neurons.

Somatostatin, galanin and peptide histidine isoleucine in the newborn and adult human trigeminal ganglion and spinal nucleus: immunohistochemistry, neuronal morphometry and colocalization with substance P

By means of indirect immunofluorescence the neuropeptides somatostatin, galanin and peptide histidine isoleucine were localized in cell bodies, nerve fibres and terminal-like elements in the ganglion and spinal nucleus of the human trigeminal nerve in perinatal and adult ages. No immunoreactivity to vasoactive intestinal polypeptide was observed. In the gasserian ganglion somatostatin-, galanin- and peptide histidine isoleucine-containing neurons and nerve fibres occurred frequently in pre- and full-term newborns, but were scarce to absent in adults. Somatostatin- and galanin-positive pericellular basket-like structures around non-immunoreactive perikarya were observed in newborn specimens. Immunoreactivity to somatostatin, galanin and peptide histidine isoleucine labelled nerve fibers and punctate and felt-like nerve terminals in the pars interpolaris and subnucleus caudalis of the spinal trigeminal nucleus, with immunostaining and distribution patterns characteristic for each peptide. In addition, somatostatin-containing neuronal cell bodies frequently were detected. At variance with those containing somatostatin, the number of galanin- and peptide histidine isoleucine-like immunoreactive elements were dramatically reduced in the adult tissue compared to the newborn one. Double immunostaining revealed that each of the three peptides partially colocalizes with substance P, the degree of coexistence being very low for somatostatin/substance P and high for galanin/substance P and peptide histidine isoleucine/substance P both in the gasserian ganglion and in the spinal nucleus. The results obtained suggest that somatostatin, galanin and peptide histidine isoleucine may play functional roles in primary sensory neurons and at the first synaptic level of the human trigeminal sensory system.

Neurotensin is an autocrine trophic factor stimulated by androgen withdrawal in human prostate cancer

After therapeutic hormone deprivation, prostate cancer cells often develop androgen-insensitive growth through mechanisms thus far undefined. Neuropeptides have been previously implicated as growth factors in some prostate cancers. Here, we demonstrate that androgen-sensitive LNCaP human prostate cancer cells produce and secrete neurotensin following androgen withdrawal. We show that while LNCaP cells express the neurotensin receptor, only androgen-deprived cells exhibit a growth response to exogenous neurotensin. We further demonstrate that androgen-stimulated cells may be refractory to exogenous neurotensin due to androgen induction of a metalloprotease active toward neurotensin. Thus, prostate cancer cells deprived of androgen develop an alternative autocrine growth mechanism involving neurotensin.

Different reinnervation patterns in the celiac/mesenteric and superior cervical ganglia following guanethidine sympathectomy in adult rats

We sought to determine whether chronic guanethidine (Gu) treatment in adult rats produces depletion of sympathetic neurons and hyperinnervation by sensory neuropeptides in the celiac/superior mesenteric (C/SMG) ganglion. Rats received Gu 40 mg/kg per day i.p or saline for 5 weeks. Upon completion of treatment, the C/SMG and the superior cervical ganglion (SCG) were examined for neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP) and vasoactive intestinal polypeptide (VIP), both by immunocytochemistry (ICC) and radioimmunoassay (RIA). Gu produced marked depletion of NPY-containing neurons and NPY content in the C/SMG, similar to that in the SCG (-89 +/- 2 vs. -92 +/- 4%, respectively). SP and CGRP immunoreactivities were significantly higher in control C/SMG as compared with SCG; after Gu treatment, there was no significant increase in either SP or CGRP in the C/SMG, however, both increased in the SCG. In contrast, VIP levels were similar in the SCG and C/SMG in controls and increased in the C/SMG but not in the SCG after Gu treatment. Thus, in adult rats, the C/SMG is as susceptible as the SCG to Gu treatment; the different pattern of hyperinnervation by SP, CGRP and VIP of the C/SMG as compared with the SCG may reflect the different sources for these neuropeptides in prevertebral as compared with paravertebral ganglia.

Ultrastructural localization of neurotensin immunoreactivity in the stellate ganglion of the cat

The morphological features and cellular relationships of neurotensin-containing axon terminals were studied at light and electron microscopic levels in the cat stellate ganglion using peroxidase and immunogold immunocytochemistry. By light microscopy, neurotensin immunoreactivity was detected within thin varicose fibres distributed throughout the ganglion. Immunoreactive fibres were no longer apparent following chronic deafferentation of the ganglion indicating that they were of extrinsic origin. Ultrastructural analysis of peroxidase immunostained material confirmed the presence of neurotensin immunoreactivity within a subpopulation of axonal varicosities which made synaptic contacts with the dendrites of ganglion cells. Within labelled varicosities neurotensin immunoreactivity was found by both immunoperoxidase and immunogold methods to be concentrated within large dense core vesicles 80-120 nm in diameter. These large dense core vesicles were characteristically distant from the active zone, in keeping with a possible extrasynaptic release of the peptide.

Depression of primary afferent-evoked responses by GR71251 in the isolated spinal cord of the neonatal rat

1. The pharmacological profile of GR71251, a new tachykinin receptor antagonist, and its effect on the responses evoked by stimulation of primary afferent fibres were studied in isolated spinal cord preparations of neonatal rats. Potential changes were recorded extracellularly from a lumbar ventral root (L3-L5). 2. Bath-application of substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) at 0.01-3 microM to the spinal cord induced depolarization of the ventral root in normal artificial cerebrospinal fluid (CSF). The NK1 agonist, acetyl-Arg6-septide, and the NK3 agonist, senktide, at 0.01-3 microM, also had potent depolarizing actions whereas two NK2 agonists, beta-Ala8NKA4-10 and Nle10NKA4-10, showed little depolarizing effects at 1 microM. 3. GR71251 (0.3-3 microM) caused a rightward shift of the concentration-response curves for SP, acetyl-Arg6-septide and NKA with pA2 values of 6.14, 6.75 or 6.70, respectively. The effects of GR71251 were readily reversible within 15-30 min after its removal. By contrast, GR71251 (1-5 microM) had little effect on the depolarizing responses to NKB and senktide. 4. GR71251 (1-3 microM) did not depress the depolarizing responses to bombesin, neuromedin B and gastrin-releasing peptide in normal artificial CSF. 5. Application of capsaicin to the spinal cord induced a depolarizing response, which was partially depressed by GR71251 (3-10 microM). 6. In the isolated spinal cord preparation, intense electrical stimulation of a dorsal root evoked a slow depolarizing response of the contralateral ventral root of the same segment. A similar slow ventral root depolarization was evoked by electrical stimulation of the ipsilateral saphenous nerve in an isolated spinal cord-saphenous nerve preparation. GR71251 (0.3-10 microM) dose-dependently depressed these slow ventral root potentials.7. In the spinal cord-peripheral nerve preparation, conditioning stimulation of the saphenous nerve evoked an inhibition of the muscle nerve-evoked monosynaptic reflex lasting about 20 s. The late part of the inhibition was markedly depressed by GR71251 (1-3 microM).8. The present results indicate that GR71251 is a potent and specific antagonist for tachykinin receptors in the spinal cord. The present study further provides evidence for the involvement of SP and NKA in the slow ventral root depolarization and the prolonged inhibition of monosynaptic reflex that are evoked by primary afferent stimulation.

Effects of colchicine applied to the peripheral nerve on the thermal hyperalgesia evoked with chronic nerve constriction

Loose ligatures placed unilaterally on the sciatic nerve results in a thermal hyperalgesia. We applied 5 or 50 mM colchicine (COL, blocker of the fast axonal transport) to the sciatic nerve and examined the effects of COL on thermal hyperalgesia and the levels of substance P (sP), calcitonin gene-related peptide (CGRP) and vasoactive intestinal polypeptide (VIP) in the spinal cord and the sciatic nerve. These data showed that the application of 50 mM COL to the sciatic nerve in this study functioned as an axonal transport blocker. COL abolished the hyperalgesic state in a concentration-dependent manner when applied proximal to the constriction injury. COL (50 mM), when applied distal to the injury, had no effect on the hyperalgesia. COL did not alter motor function or paw withdrawal response in the non-lesioned animal. Examination of peptide levels in nerve shows that COL resulted in an accumulation of sP, CGRP and VIP in the nerve. In the dorsal horn, COL resulted in a modest reduction in levels of sP and CGRP as compared to the non-lesioned side while VIP levels were elevated. These data suggest that active factors generated by the focal nerve compression and carried by fast axonal transport from the lesioned site to the spinal cord and/or dorsal ganglion are important in the development of thermal hyperalgesia after constriction injury in rats.

Impaired induction of vasoactive intestinal polypeptide after sciatic nerve injury in the streptozotocin-diabetic rat

This study was designed to assess the effects of experimental diabetes and nerve crush injury upon vasoactive intestinal polypeptide (VIP) content and axonal transport in the dorsal root ganglia (DRG) and sciatic nerve. Sciatic nerve crush injury in control and 3-week streptozotocin-diabetic rats was followed 6.5 days later by placement of 2 constricting ligatures above the site of injury. After 12 h, the L4 and L5 DRG and sciatic nerve were removed for VIP radioimmunoassay. Similar samples were also taken from control and diabetic rats whose nerve had been ligated without a preceding crush. VIP was increased over 2-fold in ganglia and 4-fold in nerves of crush-injured controls compared to uninjured controls (both P < 0.01). Crush injury also increased ganglion and nerve VIP in diabetic rats (P < 0.05 and 0.01, respectively) but the increase was less than what occurred in crush-injured controls (both P < 0.05). The accumulation of VIP proximal to a sciatic ligature was similar in control and diabetic rats and was not altered in either group by crush injury, while retrograde transport of VIP was initiated by crush injury in both control and diabetic rats. These data show that short-term diabetes does not alter the amount and peripheral axonal transport of VIP in the sciatic nerve but impairs the ability of peripheral nerve to respond to injury.

Motor dysfunction of the small bowel and colon in patients with the carcinoid syndrome and diarrhea

BACKGROUND AND METHODS

The pathophysiology of diarrhea in patients with the carcinoid syndrome is not understood. Possible causes include tumor production of neurohumoral substances, such as serotonin and substance P, which stimulate small-bowel and colonic motility, and intestinal abnormalities, such as lymphangiectasia and bacterial overgrowth. We undertook this study to determine whether carcinoid diarrhea is associated with abnormal motor function in the small intestine and colon. We measured the gastric, small-bowel, and colonic transit of radiolabeled solid residue and estimated the volume of the ascending colon in 16 patients with the carcinoid syndrome and diarrhea and 16 normal subjects. We also measured colonic tone and phasic pressure activity by intracolonic multilumen manometry and with an electronic barostat in seven patients and six normal subjects.

RESULTS

The patients with the carcinoid syndrome had elevated 24-hour urinary excretion of 5-hydroxyindoleacetic acid and elevated fasting plasma serotonin concentrations. Transit times in the small bowel and colon were two times (P < 0.001) and six times (P = 0.001) faster in the patients than in the normal subjects. The volume of the ascending colon was approximately 50 percent smaller in the patients than in the normal subjects (P < 0.001). The patients had normal fasting colonic tone; their mean postprandial colonic tone was markedly increased as compared with the values in the normal subjects (mean increase, 41 percent vs. 24 percent; P = 0.03).

CONCLUSIONS

Patients with the carcinoid syndrome who have diarrhea have major alterations in gut motor function that affect both the small intestine and colon.

The effect of intrathecal administration of RP67580, a potent neurokinin 1 antagonist on nociceptive transmission in the rat spinal cord

The effect of intrathecal application of the selective neurokinin 1 (NK1) receptor antagonist RP67580 and its enantiomer RP68651 was studied on the responses of dorsal horn nociceptive neurones to formalin in the rat. The first and second phases of the formalin response were inhibited by RP67580 in a dose-related manner (1-10 micrograms), whereas RP68651 (5 micrograms) facilitated the second phase of the response. The same doses of RP67580 had minimal effects on the acute C-fibre responses. The NK1 receptor appears to play a role in prolonged nociceptive transmission in the spinal cord.

Effects of intrathecal strychnine and bicuculline on nerve compression-induced thermal hyperalgesia and selective antagonism by MK-801

We studied the effects of intrathecally administered strychnine (STR; glycine antagonist; 10 or 30 micrograms) and bicuculline (BIC; GABAA antagonist 1 or 3 micrograms) on the thermal hyperalgesia which occurs following sciatic nerve constriction injury in rats. Following unilateral application of loose ligatures around the sciatic nerve, all rats typically displayed an ipsilateral thermal hyperalgesia on day 7. Intrathecal STR or BIC administered just after the nerve lesion and on days 1 and 2 after the nerve lesion significantly enhanced in a dose-dependent fashion the magnitude of the thermal hyperalgesia normally observed on day 7, as compared to intrathecal saline (for STR: 30 micrograms > 10 micrograms > or = saline; for BIC: 30 micrograms > 10 micrograms > or = saline, p < 0.05). Intrathecal MK-801, an N-methyl-D-aspartate antagonist, was without effect upon the response latency of the normal or sham operated paw, but selectively reversed the hyperalgesia. These results suggest that the loss of a spinal STR- and BIC-sensitive inhibition augments development of the hyperalgesia induced by chronic nerve compression.

Enteroendocrine peptides in a canine model of orthotopic jejunoileal autotransplantation

The enteroendocrine cells of the small bowel provide a rich source of regulatory peptides involved in the modulation of gastrointestinal function. Recent work from our laboratory showed that in situ neural isolation (autotransplantation) of the jejunoileum produced marked changes in tissue expression of several neuropeptides. In the present study, we examined the influence of extrinsic innervation on the tissue expression of endocrine peptides localized to various regions of the gastrointestinal tract. Concentrations of immunoreactive gastric inhibitory polypeptide (GIP), neurotensin (NT) and peptide tyrosine tyrosine (PYY) in fasting plasma and regional tissue biopsies were determined before and at varying time points (2, 6, 12 weeks) after a model of canine orthotopic jejunoileal autotransplantation. GIP was not altered in plasma or tissue at any time point. Plasma concentrations of NT and PYY increased after autotransplantation. Following a decrease in tissue concentrations two weeks after autotransplantation, NT increased progressively from 2 to 6 to 12 weeks, reaching a maximal increase of 895% over baseline in proximal ileum. Tissue concentrations of PYY followed much the same pattern as NT, but these trends never achieved statistical significance. Chromatographic characterization of tissue biopsy extracts revealed molecular heterogeneity of NT-like immunoreactivity, while GIP and PYY immunoreactivity coeluted as single species with authentic standards. Taken together with our earlier observations, it appears that disruption of extrinsic and intrinsic neural continuity to the jejunoileum (autotransplantation) does not affect gut endocrine peptides such as GIP and PYY to the same extent as enteric neuropeptides. NT has been localized to neural as well as endocrine cells and is involved in the temporal adaptive response to autotransplantation.

Effect of peripheral nerve cut on neuropeptides in dorsal root ganglia and the spinal cord of monkey with special reference to galanin

Using the indirect immunofluorescence method and in situ hybridization, the localization and levels of immunoreactivities and mRNAs for several neuropeptides were studied in lumbar dorsal root ganglia and spinal cord of untreated monkeys (Macaca mulatta) and after unilateral transection of the sciatic nerve. Immunoreactive galanin, calcitonin gene-related peptide, substance P and somatostatin and their mRNAs were found in cell bodies in dorsal root ganglia of untreated monkeys and on the contralateral side of the monkeys with unilateral sciatic nerve lesion. After axotomy there was a marked decrease in the number of calcitonin gene-related peptide-, substance P- and somatostatin-positive neurons in dorsal root ganglia ipsilateral to the lesion, whereas the number of galanin positive cells strongly increased. A few neuropeptide tyrosine-positive cells were seen in after axotomy, whereas no such neurons were found in controls. No vasoactive intestinal polypeptide-, peptide histidine isoleucine-, cholecystokinin-, dynorphin-, enkephalin-, neurotensin- or thyrotrophin releasing hormone-positive cell bodies were seen in dorsal root ganglia of any of the groups studied. In the dorsal horn of the spinal cord all peptide immunoreactivities described above, except thyrotropin releasing hormone, were found in varying numbers of nerve fibres with a similar distribution in untreated monkeys and in the contralateral dorsal horn in monkey with unilateral sciatic nerve lesion. Two cholecystokinin antisera were used directed against the C- and N-terminal portions, respectively, showing a distinctly different distribution pattern in the dorsal horn. Somatostatin- and dynorphin-like immunoreactivities were also observed in small neurons in the dorsal horn. No certain effect of axotomy on these interneurons could be seen. However, marked changes were observed after this type of lesion for some peptide containing fibres in the ipsilateral dorsal horn. Thus, there was a marked increase in galanin-like immunoreactivity, whereas calcitonin gene-related peptide-, substance P-, somatostatin-, peptide histidine isoleucine neurotensin- and cholecystokinin-like immunoreactivities decreased. No changes could be observed in neuropeptide tyrosine or enkephalin-positive fibres. The present results demonstrate marked ganglionic and transganglionic changes in peptide levels after peripheral axotomy. When compared to published results on the effect of axotomy on peptides in dorsal root ganglia and spinal cord of rat, both similarities and differences were encountered.(ABSTRACT TRUNCATED AT 400 WORDS)

Autonomic dysfunction in patients with chronic intestinal pseudo-obstruction

We prospectively evaluated autonomic function in 50 patients with clinical and manometric features of a neuropathic form of chronic intestinal pseudo-obstruction (CIP). In 26 patients, there were underlying disease processes that may have affected extrinsic neural control to viscera: diabetes mellitus (n = 16), previous gastric surgery (n = 5), and other neurologic disorders (n = 5). Our aim was to characterize autonomic function in these patients, and those 24 with CIP unassociated with a known underlying neurologic disorder (idiopathic group). We assessed vagal function and sympathetic cholinergic and adrenergic function by means of standardized autonomic tests and quantitated postprandial antral pressure activity. We also measured postprandial levels of pancreatic polypeptide and neurotensin as indicators of vagal function and of the delivery of nutrients to the distal small bowel. Among the idiopathic group (n = 24), two had evidence of a generalized sympathetic neuropathy and five abdominal vagal dysfunction (one had both). Among diabetic patients, three had sympathetic adrenergic failure, six had orthostasis with normal plasma noradrenaline, ten had signs of generalized sympathetic neuropathy and eight had abdominal vagal dysfunction. Vagal dysfunction was identified in all three patients who underwent vagotomy as part of their previous gastric surgery. In the other neurologic syndromes, vagal function was abnormal in three of the five patients. Thus, autonomic and, particularly, vagal dysfunction are confirmed in a majority of patients with CIP associated with known diabetes or neurologic disorders; however, a previously unrecognized autonomic (chiefly vagal) neuropathy of undetermined cause has been identified in five of the 24 'idiopathic' CIP patients.

Neuropeptides in the human celiac/superior mesenteric ganglionic complex: an immunohistochemical study

The occurrence of vasoactive intestinal polypeptide (VIP), peptide histidine-isoleucine (PHI), calcitonin gene-related peptide (CGRP), substance P (SP), somatostatin (SOM), galanin (GAL) and enkephalins (ENK) is studied in the human celiac/superior mesenteric ganglionic complex of pre- and full-term newborns, and adult subjects by means of immunohistochemistry. The antisera used labelled nerve fibres and terminal-like networks for each examined peptide, as well as VIP- and SOM-positive postganglionic neurons. Differences in the relative amount and density of the structures immunoreactive to the various peptides were observed. Moreover, variations in the amount and type of labelled elements were appreciable for each peptide when specimens from subjects at perinatal and adult ages were compared. Double-labelling immunofluorescence for SP and each other peptide showed that co-localization with SP is very frequent for CGRP, moderate to scarce for GAL and SOM, and rare to absent for PHI, VIP and ENK. VIP-, ENK- and CGRP-immunolabeled perikarya bearing the morphological features of the small intensely fluorescent (SIF) cells occurred in the organ. The presence of a paraganglion in one of the specimens examined allowed the detection of VIP- and ENK-positive cell bodies and VIP-, ENK-, SP- and GAL-like immunoreactive varicose nerve fibres in it. The results obtained provide substantial morphological data in support of the involvement of the examined peptides in the chemical interneuronal signalling in the human celiac/superior mesenteric ganglia.

Effects of intrathecal capsaicin and an NK-1 antagonist, CP,96-345, on the thermal hyperalgesia observed following unilateral constriction of the sciatic nerve in the rat

We evaluated the effect of intrathecal (i.t.) capsaicin (CAP) and the NK-1 selective non-peptidic antagonist, CP,96-345, on the thermal hyperalgesia ordinarily observed after unilateral partial ligation of the sciatic nerve in rats. CAP was injected i.t. 2 days after constriction injury. Seven days after partial ligation, the levels of substance P (sP), calcitonin gene-related peptide (CGRP) and vasoactive intestinal polypeptide (VIP) were the same in the left and right dorsal horns of the lesioned rats which were injected with vehicle (VEH). CAP (75 micrograms/15 microliters of 20% 2-hydroxypropyl-beta-cyclodextrin) resulted in an equal reduction (40-50%) in the dorsal horn levels of sP and CGRP, but not VIP. After 7 days, i.t. CAP increased the paw withdrawal latency (PWL) of the non-injured hind paw. In contrast, there was no change in the PWL of the injured paw when compared to that of VEH-treated animals. Thus, CAP did not abolish the hyperalgesic state. We concluded that the thermal hyperalgesia after sciatic nerve constriction injury is not mediated by CAP-sensitive C fibers. CP,96-345 given i.t. at a dose which is physiologically active (400 micrograms) had little effect on the thermal response latency of either the normal or hyperesthetic paw. This provides further evidence that neither the normal pain response nor hyperalgesic state is dependent upon a dorsal horn action of sP.

Guanethidine sympathectomy increases substance P concentration in the superior sympathetic ganglion of adult rats

Adult rats received intraperitoneal injections of guanethidine or saline for 5 weeks. Six to 8 weeks following completion of treatment, concentrations of substance P and neuropeptide Y (NPY) were measured by radioimmunoassay in the superior cervical ganglion (SCG) and thoracic spinal cord. The SCG was also immunostained for NPY and substance P. No differences were observed in thoracic spinal cord content of either NPY or substance P. We observed depletion of NPY immunoreactive neurons and NPY levels in the SCG, and pharmacologic evidence of postganglionic denervation in guanethidine-treated rats. In guanethidine-treated rats, there was a marked increase of substance P levels in the SCG, where substance P was localized in fibers, but not cell bodies. Thus, sprouting of substance P-containing sensory fibers in the sympathetic ganglia occurs following postganglionic sympathectomy in adult rats.

Increased calcitonin gene-related peptide- and cholecystokinin-like immunoreactivities in spinal motoneurones after dorsal rhizotomy

Possible changes in neuropeptides within the ventral horn of the spinal cord were investigated after unilateral dorsal rhizotomy at the lumbar level (L1-L6) in adult rats. Ten days after the surgery, immunohistochemical observations and radioimmunological determinations confirmed a marked loss of calcitonin gene-related peptide (CGRP)- and substance P (SP)-like immunoreactivities within the superficial layers of the deafferented dorsal horn, as expected from the degeneration of primary afferent fibres containing these peptides. A concomitant increase in immunohistochemical staining and levels of CGRP (+296%) and CCK (+71%)-like immunoreactivities was observed in the ipsilateral ventral horn where both peptides are located in motoneurones. In contrast, substance P-like immunoreactivity that is confined to fibres and terminals within the ventral horn, was not altered by dorsal rhizotomy. These data indicate that the expression of neuropeptides in spinal motoneurones can be influenced by primary afferent inputs.

Effect of early feeding on maturation of the preterm infant's small intestine

To determine the response of the preterm infant's intestine to entire feedings at different postnatal ages, we recorded results of manometry of the gastroduodenum and determined fasting plasma concentrations of gastrin, gastric inhibitory peptide, neurotensin, and peptide YY three times in each of two groups: 27 preterm infants were randomly assigned to receive hypocaloric enteral nutrition on postnatal days 3 to 5 (early feeding) or on days 10 to 14 (late feeding). Initial observations (study 1) were performed by the fifth postnatal day; study 2 was performed on days 10 to 14, and study 3 on days 24 to 28. Early-fed infants received hypocaloric feedings immediately after study 1; late-fed infants did not receive enteral feedings until the completion of study 2. Although motor activity and fasting gastrointestinal peptide concentrations did not differ between groups at study 1, at study 2 early-fed infants had significantly more mature motor patterns than did babies not being fed. Early-fed infants also had significantly higher plasma concentrations of gastrin and gastric inhibitory peptide than did late-fed infants; neurotensin and peptide YY values were similar in both groups. By the time of study 3, when late-fed infants had also received enteral feedings, gut development was not different in the two groups. However, early-fed infants were able to tolerate full oral nutrition sooner, had fewer days of feeding intolerance, and had shorter hospital stays. Thus the provision of early hypocaloric nutrition was associated with earlier nutrition of preterm infants' intestinal function and resulted in improved feeding tolerance. These findings support the use of early feedings in preterm infants.

Distribution of neurokinin B in rat spinal cord and peripheral tissues: comparison with neurokinin A and substance P and effects of neonatal capsaicin treatment

In the present study, highly specific radioimmunoassays were developed and used to measure neurokinin B, neurokinin A and substance P in the rat spinal cord and various peripheral tissues. The results are as follows. (1) Neurokinin B and neurokinin A were distributed all along the rostrocaudal axis of the spinal cord, as is substance P, and were more concentrated in the dorsal than in the ventral region. (2) Substance P was more abundant in the central and peripheral nervous tissues than neurokinin A, while in certain peripheral organs, neurokinin A was more abundant than substance P. In the spinal cord, neurokinin B concentrations were lower than those of the other two tachykinins. (3) In contrast to neurokinin A and substance P, neurokinin B was not detected in any of the peripheral tissues examined. (4) Capsaicin treatment reduced by half neurokinin A and substance P concentrations in the dorsal region of the spinal cord, the dorsal root ganglia and the sciatic nerve, but was without effect on neurokinin B concentrations in the spinal cord. Neurokinin A, like substance P, may therefore have an important function in the transmission of sensory information, particularly in nociceptive transmission from the periphery to the spinal cord and in peripheral neurogenic inflammation. In contrast, since neurokinin B was not found in the sensory neurons, it is not likely to have these functions, but may perhaps control them.

The CCK-A and CCK-B receptor antagonists, devazepide and L-365,260, enhance morphine antinociception only in non-acclimated rats exposed to a novel environment

Devazepide, a potent CCK-A receptor antagonist, and L-365,260, a selective CCK-B receptor antagonist, have been introduced as pharmacologic tools for differentiating the physiologic roles of CCK-A and CCK-B receptor subtypes. In the present study, we tested the effects of devazepide and L-365,260, on morphine antinociception in rats using the thermal sensorimotor tail flick test. Both devazepide and L-365,260 significantly enhanced the antinociceptive action of morphine, but only in rats that had not been acclimated to the laboratory environment or habituated to investigator handling. When tested with fully acclimated animals, devazepide and L-365,260 had no effect whatsoever; they neither enhanced nor attenuated morphine-induced antinociception. These observations indicate that the effects of devazepide and L-365,260, CCK antagonists, on morphine antinociception appear to be dependent on the animal's response to a new environment or to the stress induced by an unaccustomed experimental paradigm.

Tissue distribution and innervation pattern of peptide immunoreactivities in the rat pancreas

The distribution of calcitonin gene-related peptide (CGRP), substance P/tachykinin (SP/TK), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY) and gastrin-releasing peptide (GRP) immunreactivities (IR) in the rat pancreas was investigated using radioimmunoassay and immunohistochemistry. CGRP, NPY and VIP tissue contents are much higher than GRP and SP/TK concentrations. Peptide-containing nerves are distributed to both the exocrine and endocrine pancreas. However, differences exist in terms of density and targets of innervation for each peptidergic system. In the acini and through the stroma, fibers IR for CGRP, NPY and VIP are greater than GRP- and SP/TK-containing processes. The vasculature is supplied by a prominent NPY, CGRP and, to a lesser extent, SP/TK innervation. VIP-IR is found occasionally, and GRP-IR is never detected, in fibers associated with blood vessels. Around ducts, CGRP- and NPY-positive neurites are greater than SP/TK- greater than or equal to VIP-IR fibers, whereas GRP-containing nerves are not visualized. In the islets, the density of peptidergic nerves is: VIP-, GRP- greater than or equal to CGRP-IR greater than NPY or SP/TK. In intrapancreatic ganglia. VIP- and, to a lesser extent, NPY-IRs are found in numerous neuronal cell bodies and in nerve fibers; GRP-IR is present in numerous nerve processes and in few cell bodies; CGRP- and SP/TK-IRs are detected only in fibers wrapping around unlabeled ganglion cells. The majority of CGRP-IR fibers contain SP/TK-IR. The existence of differential patterns of peptidergic nerves suggests that peptides exert their effects on pancreatic functions via different pathways.

Distribution of vasoactive intestinal peptide- and peptide histidine isoleucine amide-like immunoreactive neurons and fibers in the thoracic spinal cord of the rat

The distributions of vasoactive intestinal peptide (VIP)- and peptide histidine isoleucine amide (PHI)-immunoreactivities (IR) in the thoracic spinal cord of the rat are described. VIP- and PHI-IR were present in cells and fibers in the lateral spinal nucleus, lamina VII, nucleus proprius, substantia gelatinosa, intermediolateral cell column, and the area around the central canal. The functions of these peptides in the thoracic spinal cord are not known; however, their locations suggest that they are involved in sensory and autonomic functions, among others.