The distribution and origin of VIP in the spinal cord of six mammalian species

Dorsal Horn of Mouse Lumbar Spinal Cord Imaged with CLARITY

The organization of the mouse spinal dorsal horn has been delineated in 2D for the six Rexed laminae in our publication Atlas of the Spinal Cord: Mouse, Rat, Rhesus, Marmoset, and Human. In the present study, the tissue clearing technique CLARITY was used to observe the cyto- and chemoarchitecture of the mouse spinal cord in 3D, using a variety of immunohistochemical markers. We confirm prior observations regarding the location of glycine and serotonin immunoreactivities. Novel observations include the demonstration of numerous calcitonin gene-related peptide (CGRP) perikarya, as well as CGRP fibers and terminals in all laminae of the dorsal horn. We also observed sparse choline acetyltransferase (ChAT) immunoreactivity in small perikarya and fibers and terminals in all dorsal horn laminae, while gamma aminobutyric acid (GABA) and glutamate decarboxylase-67 (GAD67) immunoreactivities were found only in small perikarya and fibers. Finally, numerous serotonergic fibers were observed in all laminae of the dorsal horn. In conclusion, CLARITY confirmed the 2D immunohistochemical properties of the spinal cord. Furthermore, we observed novel anatomical characteristics of the spinal cord and demonstrated that CLARITY can be used on spinal cord tissue to examine many proteins of interest.

The spinal cord of the common marmoset (Callithrix jacchus)

The marmoset spinal cord possesses all the characteristic features of a typical mammalian spinal cord, but with some interesting variation in the levels of origin of the limb nerves. In our study Nissl and ChAT sections of the each segment of the spinal cord in two marmosets (Ma5 and Ma8), we found that the spinal cord can be functionally and anatomically divided into six regions: the prebrachial region (C1 to C3); the brachial region (C4 to C8) - segments supplying the upper limb; the post-brachial region (T1 to L1) - containing the sympathetic outflow, and supplying the hypaxial muscles of the body wall; the crural region (L2 to L5) - segments supplying the lower limb; the postcrural region (L6) - containing the parasympathetic outflow; and the caudal region (L7 to Co4) - supplying the tail. In the rat, mouse, and rhesus monkey, the prebrachial region consists of segments C1 to C4 (with the phrenic nucleus located at the C4 segment), and the brachial region extends from C5 to T1 inclusive. The prefixing of the upper limb outflow in these two marmosets mirrors the finding in the literature that a large C4 contribution to the brachial plexus is common in humans.

Therapeutic potential of neuropeptide Y (NPY) receptor ligands

Neuropeptide Y (NPY) is widely distributed in the human body and contributes to a vast number of physiological processes. Since its discovery, NPY has been implicated in metabolic regulation and, although interest in its role in central mechanisms related to food intake and obesity has somewhat diminished, the topic remains a strong focus of research concerning NPY signalling. In addition, a number of other uses for modulators of NPY receptors have been implied in a range of diseases, although the development of NPY receptor ligands has been slow, with no clinically approved receptor therapeutics currently available. Nevertheless, several interesting small molecule compounds, notably Y2 receptor antagonists, have been published recently, fueling optimism in the field. Herein we review the role of NPY in the pathophysiology of a number of diseases and highlight instances where NPY receptor signalling systems are attractive therapeutic targets.

Phenotypic diversity and expression of GABAergic inhibitory interneurons during postnatal development in lumbar spinal cord of glutamic acid decarboxylase 67-green fluorescent protein mice

The synthesis enzyme glutamic acid decarboxylase (GAD65 or GAD67) identifies neurons as GABAergic. Recent studies have characterized the physiological properties of spinal cord GABAergic interneurons using lines of GAD67-green fluorescent protein (GFP) transgenic mice. A more complete characterization of their phenotype is required to better understand the role of this population of inhibitory neurons in spinal cord function. Here, we characterize the distribution of lumbar spinal cord GAD67-GFP neurons at postnatal days (P) 0, 7, and 14, and adult based on their co-expression with GABA and determine the molecular phenotype of GAD67-GFP neurons at P14 based on the expression of various neuropeptides, calcium binding proteins, and other markers. At all ages >67% of GFP(+) neurons were also GABA(+). With increasing age; (i) GFP(+) and GABA(+) cell numbers declined, (ii) ventral horn GFP(+) and GABA(+) neurons vanished, and (iii) somatic labeling was reduced while terminal labeling increased. At P14, vasoactive intestinal peptide and bombesin were expressed in approximately 63% and approximately 35% of GFP(+) cells, respectively. Somatostatin was found in a small number of neurons, whereas calcitonin gene-related peptide never co-localized with GFP. Moderate co-expression was found for all the Ca(2+) binding proteins examined. Notably, most laminae I-II parvalbumin(+) neurons were also GFP(+). Neurogranin, a protein kinase C substrate, was found in approximately 1/2 of GFP(+) cells. Lastly, while only 7% of GFP(+) cells contain nitric oxide synthase (NOS), these cells represent a large fraction of all NOS(+) cells. We conclude that GAD67-GFP neurons represent the majority of spinal GABAergic neurons and that mouse dorsal horn GAD67-GFP(+) neurons comprise a phenotypically diverse population.

The role of vasoactive intestinal polypeptide and pituitary adenylate cyclase-activating polypeptide in the neural pathways controlling the lower urinary tract

Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are expressed in the neural pathways regulating the lower urinary tract. VIP-immunoreactivity (IR) is present in afferent and autonomic efferent neurons innervating the bladder and urethra, whereas PACAP-IR is present primarily in afferent neurons. Exogenously applied VIP relaxes bladder and urethral smooth muscle and excites parasympathetic neurons in bladder ganglia. PACAP relaxes bladder and urethral smooth muscle in some species (pig) but excites the smooth muscle in other species (mouse). Intrathecal administration of VIP in cats with an intact spinal cord suppresses reflex bladder activity, but intrathecal administration of VIP or PACAP in rats enhances bladder activity and suppresses urethral sphincter activity. PACAP has presynaptic facilitatory effects and direct excitatory effects on lumbosacral parasympathetic preganglionic neurons. Chronic spinal cord transection produces an expansion of VIP-IR (cats) and PACAP-IR (rats) in primary afferent axons in the lumbosacral spinal cord and unmasks spinal excitatory effects of VIP on bladder reflexes in cats. Intrathecal administration of PACAP6-38, a PAC1 receptor antagonist, reduces bladder hyperactivity in chronic spinal-cord-injured rats. These observations raise the possibility that VIP or PACAP have a role in the control of normal or abnormal voiding.

Distribution of vasoactive intestinal polypeptide in the rat heart: effect of guanethidine and capsaicin

Vasoactive intestinal polypeptide (VIP) is believed to coexist with acetylcholine in postganglionic parasympathetic neurones. However, the presence of VIP in extrinsic nerves and/or other types of intrinsic cardiac neurones has not been excluded. The aim of our study was to examine the distribution and origin of VIP-ergic innervation in the rat heart atria using immunocytochemistry and radioimmunoassay (RIA) combined with two types of denervation: sympathectomy, which was produced by guanethidine treatment and sensory denervation achieved by capsaicin administration. In whole-mount preparations of the intact atria, VIP-immunoreactive (IR) nerve fibres and ganglionic cells were found, the latter being much more numerous in the left atria (LA) than in the right ones. Some of VIP-IR nerve fibres forming bundles appeared to be extrinsic in origin. VIP-IR concentrations determined by RIA in the intact rats were significantly higher in the LA than in the right ones (p < 0.01). However, no changes in VIP-IR levels were found in either atrium after both guanethidine and capsaicin treatment protocols, thus indicating that VIP-immunoreactivity is not associated with either sympathetic or sensory innervation. In conclusion, the ganglionated plexus of the rat atria may comprise at least 3 different neuronal populations expressing VIP-positivity: 1. extrinsic preganglionic parasympathetic fibres, 2. intrinsic postganglionic parasympathetic neurones and 3. intrinsic local circuit neurones that do not express a cholinergic phenotype.

Plasma levels of substance P, neuropeptide Y and vasoactive intestinal polypeptide in patients with chronic tension-type headache

Animal and human studies have shown that substance P (SP), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) are involved in the pathophysiology of acute and chronic pain conditions. The primary aim of the present study was to compare plasma levels of SP, NPY and VIP in external jugular vein between patients with chronic tension-type headache and healthy controls. The secondary aim was to examine plasma levels of these neuropeptides in relation to headache state. In addition, we wanted to study the relation between cranial circulation (jugular vein) and peripheral circulation (antecubital vein). Blood from the external jugular and antecubital vein was drawn from 20 patients with chronic tension-type headache and 20 healthy controls. Plasma SP in patients, 2.0 (1.4-2.2) pmol/l, did not differ significantly from plasma SP in controls, 1.7 (1.1-2.1) pmol/l, (P=0.44). No significant differences were found between SP levels on days with headache, 1.5 (0.3-1.7) pmol/l, and SP levels on days without headache, 1.7 (1.1-1. 9) pmol/l, (P=0.06). Plasma NPY in patients, 118+/-3 pmol/l, did not differ significantly from plasma NPY in controls, 113+/-5 pmol/l, (P=0.40). There was no difference between NPY levels on days with headache, 120+/-3 pmol/l, and on days without headache, 118+/-3 pmol/l, (P=0.73). VIP levels in patients, 6 (4-7) pmol/l, did not differ significantly from VIP levels in controls, 5 (5-7) pmol/l, (P=0.50). No significant differences were found between VIP levels measured on days with headache, 5 (4-6) pmol/l, and VIP levels measured on days without headache, 6 (4-7) pmol/l, (P=0.81). Plasma levels of SP, NPY and VIP did not significantly differ between the peripheral and the cranial circulation neither in patients nor in controls (0.05). In summary, the present study indicates that plasma levels of SP, NPY and VIP are normal in chronic tension-type headache patients and largely unrelated to headache state.

Vasoactive intestinal polypeptide produces depolarization and facilitation of C-fibre evoked synaptic responses in superficial dorsal horn neurones (laminae I-IV) of the rat lumbar spinal cord in vitro

The actions of vasoactive intestinal polypeptide (VIP) were investigated on superficial dorsal horn (LI-IV) neurones in longitudinal slices of the rat lumbar spinal cord in vitro. Bath application of VIP (1-2 mM) cause depolarizations which were accompanied by a lowering of the threshold for excitation of the neurone by current injection in the majority of cells studied. In some cases these depolarizations were very large and caused depolarization block and prolonged desensitization. An increase in spontaneous excitatory postsynaptic potential (EPSP) frequency and amplitude was also produced by VIP. Synaptic responses evoked by peripheral nerve stimuli at intensities which recruited C-fibres were also facilitated by VIP. The principle action was on the later components of these responses which are dependent on C-fibre activation. EPSP summation evoked by trains of peripheral nerve stimulation (wind-up) was also facilitated by VIP and the duration of these responses was clearly increased. These observations are discussed briefly in the context of the possible role of VIP in neuropathic pain.

Vasoactive intestinal polypeptide in sacral primary sensory pathways in the cat

Unmyelinated sensory axons in the sacral spinal cord may play a role in bladder reflexes under certain pathological conditions. Previous data suggested vasoactive intestinal polypeptide (VIP) might be contained exclusively in sensory C-fibers, some of which innervate the bladder. This study was undertaken to describe the morphology of these VIP fibers in the sacral cord of the cat. VIP immunoreactivity was confined to unmyelinated axons observed at several levels of the sensory pathway including the dorsal root ganglia, dorsal roots, Lissauer's tract, and the lateral collateral pathway. A combination of light and electron microscopic observations showed VIP-immunoreactive fibers with labeled varicosities and synaptic terminals in laminae I, IIo, V, VII, and X. VIP-immunolabeled varicosities had a mean diameter of 1.6 microm (range = 0.11-7.4 microm, S.D. = 1.01, n = 311) with a small percentage (8%) being relatively large (3-7.4 microm). VIP varicosities contained a mixture of small clear vesicles (CLV) and large dense core vesicles (LDV). Although most varicosities contained a moderate number of LDVs (14.86 LDVs/microm2), some varicosities contained a large number of LDVs, whereas others contained very few. Varicosities that possessed synaptic specializations were classed as terminals and were divided into three morphological classes. Two of these resembled Gray's Type I terminal, whereas a third was similar to the Gray's Type II terminal. There was no consistent relationship between vesicle content of the terminal and the type of synaptic contact it possessed. This study shows that in the sacral spinal cord of the cat, VIP terminals originate only from C-fibers, terminate primarily in laminae I and V, and exhibit a variety of morphologies consistent with heterogeneous origins and functions of the lower urinary tract.

Identification of uterine-related sympathetic neurons in the rat inferior mesenteric ganglion: neurotransmitter content and afferent input

The rat uterus is innervated by sensory and autonomic nerves. Sensory and sympathetic fibers travel in the hypogastric nerves and are associated with the thoracolumbar spinal cord levels T13-L3. The inferior mesenteric ganglion (IMG) contains the somata of sympathetic postganglionic neurons and some of these may project axons to the uterus. Sensory and parasympathetic fibers travel in the pelvic nerve and are associated with the lumbosacral cord levels L6-S1 and pelvic ganglion (PG). We previously reported data concerning the neurochemical anatomy of the PG with regard to the uterine innervation; the present study was undertaken to characterize the neurochemical anatomy of the IMG with regard to it involvement in uterine innervation. A retrograde axonal tracer was used to verify projections of axons of IMG neurons to the uterus. Immunostaining of cryostat sections of the IMG revealed neurons immunoreactive for neuropeptide Y (NPY) and for tyrosine hydroxylase (TH). Immunostaining for the synaptic terminal protein synapsin I (SYN) revealed numerous fine terminals immediately surrounding the principal neurons and in the interneuronal spaces. Varicosities immunoreactive for calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), enkephalin (ENK), substance P (SP) and galanin (GAL) appear to be associated with principal neurons. Additional varicosities stained for nicotinamide adenine dinucleotide phosphate (reduced)-diaphorase (NADPH-d) and nitric oxide synthase (NOS), thus indicating sites of neuronal nitric oxide synthesis. This study revealed that the IMG contains uterine-related neurons and that some of the retrogradely labeled uterine-related neurons contain NPY, TH or both NPY/TH. In addition, uterine-related neurons received abundant afferent inputs indicated by SYN-immunoreactive (-ir) terminals and some of these varicosities labeled for GAL, CGRP, VIP, ENK, or NADPH-d/NOS.

Localization of NADPH diaphorase in the lumbosacral spinal cord and dorsal root ganglia of the cat

The distribution of NADPH-d activity in the spinal cord and dorsal root ganglia of the cat was studied to evaluate the role of nitric oxide in lumbosacral afferent and spinal autonomic pathways. At all levels of the spinal cord NADPH-d staining was present in neurons and fibers in the superficial dorsal horn and in neurons around the central canal and in the dorsal commissure. In addition, the sympathetic autonomic nucleus in the rostral lumbar segments exhibited prominent NADPH-d cellular staining whereas the parasympathetic nucleus in the sacral segments was not well stained. The most prominent NADPH-d activity in the sacral segments occurred in fibers extending from Lissauer's tract through laminae I along the lateral edge of the dorsal horn to lamina V and the region of the sacral parasympathetic nucleus. These fibers were very similar to VIP-containing and pelvic nerve afferent projections in the same region. They were prominent in the S1-S3 segments but not in adjacent segments (L6-L7 and Cx1) or in thoracolumbar and cervical segments. NADPH-d activity and VIP immunoreactivity in Lissauer's tract and the lateral dorsal horn were eliminated or greatly reduced after dorsal-ventral rhizotomy (S1-S3), indicating the fibers represent primary afferent projections. A population of small diameter afferent neurons in the L7-S2 dorsal root ganglia were intensely stained for NADPH-d. The functional significance of the NADPH-d histochemical stain remains to be determined; however, if NADPH-d is nitric oxide synthase then this would suggest that nitric oxide may function as a transmitter in thoracolumbar sympathetic preganglionic efferent pathways and in sacral parasympathetic afferent pathways in the cat.

Ultrastructural studies on peptides in the dorsal horn of the spinal cord--I. Co-existence of galanin with other peptides in primary afferents in normal rats

The aim of the present study was to investigate galanin-like immunoreactivity in primary afferent terminals and its relationship to other neuropeptides in laminae I and II of the fourth and fifth lumbar segments of normal rat spinal cord using immunofluorescence and pre- and post-embedding electron-microscopic immunocytochemistry. Triple-immunofluorescence staining showed that galanin-like immunoreactivity co-localized with substance P- and calcitonin gene-related peptide-like immunoreactivities in many nerve fibres and terminals in laminae I and II of the dorsal horn. At the ultrastructural level, using pre-embedding immunocytochemistry, galanin-like immunoreactivity was found in type I glomeruli with an electron-dense central terminal containing many densely packed synaptic vesicles and several large dense-core vesicles. Both the cytoplasm and the core of the large vesicles were immunoreactive. In type II glomeruli with an electron-lucent central terminal and loosely packed synaptic vesicles the large dense-core vesicles and the cytoplasm were only weakly galanin-positive. Post-embedding immunocytochemistry revealed that galanin-like immunoreactivity co-existed with substance P- and calcitonin gene-related peptide-like immunoreactivities in many terminals and in individual large dense-core vesicles in lamina II. These terminals were considered to represent primary afferents, since there is evidence that calcitonin gene-related peptide in the dorsal horn only occurs in nerve endings originating in dorsal root ganglia. Evidence was also unexpectedly obtained for the occurrence of several other peptides in calcitonin gene-related peptide-positive terminals, i.e. in presumably primary afferents. Thus galanin-like immunoreactivity sometimes also co-localized with cholecystokinin- and neuropeptide tyrosine-like immunoreactivities in calcitonin gene-related peptide-immunoreactive terminals and in some large dense-core vesicles in such terminals. A small number of calcitonin gene-related peptide immunoreactive, presumably primary afferent terminals contained enkephalin-, neurotensin- (and galanin-)like immunoreactivities. These results indicated that galanin can be co-stored with several other neuropeptides in large dense-core vesicles in primary afferent terminals and may presumably be released together with them in the superficial layer of the dorsal horn. Since various combinations of peptides, presumably at varying concentrations, occur in the large dense-core vesicles in a given nerve ending, it is likely that the individual large dense-core vesicles produced in a neuron are heterogenous with regard to peptide content and thus to the message that they transmit upon release.

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)

Facilitatory effect of vasoactive intestinal polypeptide on spinal and peripheral micturition reflex pathways in conscious rats with and without detrusor instability

In unanesthetized, normal rats, and rats with bladder hypertrophy following infravesical outflow obstruction, cystometry was performed to investigate the effects of spinal and peripheral administration of vasoactive intestinal polypeptide (VIP) on micturition. In addition, the direct effects of the peptide on isolated smooth muscle preparations of detrusor and urethra were studied. In normal animals, 10 micrograms. of VIP administered intrathecally as well as intra-arterially close to the bladder, but not intravenously, decreased micturition volume and bladder capacity, and facilitated spontaneous bladder contractions. In animals with bladder hypertrophy, the same dose of VIP intrathecally had similar effects on these three parameters, but the effects of VIP given intra-arterially were less pronounced. VIP given intravenously was ineffective. Hexamethonium 5 mg. x kg.-1 given intraarterially did not block the stimulatory effect of VIP 10 micrograms. given intra-arterially to normal animals. VIP had negligible effects on isolated detrusor muscle contracted by carbachol or electrical stimulation, or on urethral preparations contracted by noradrenaline. These results suggest that VIP has a facilitatory action on the micturition reflex at the spinal cord and ganglionic levels.

Release of calcitonin gene-related peptide (CGRP), substance P (SP), and vasoactive intestinal polypeptide (VIP) from rat spinal cord: modulation by alpha 2 agonists

Release of calcitonin gene-related peptide (CGRP) and substance P (SP) from the rat lumbar dorsal spinal cord and vasoactive intestinal polypeptide (VIP) from the sacral spinal cord was examined under resting conditions (baseline release) and in the presence of capsaicin (CAP). Baseline rates of CGRP, SP, and VIP release were 1.71 +/- 0.19, 0.12 +/- 0.01, and 0.097 +/- 0.029 pg/mg/min, respectively. The addition of CAP (10 microM) to the perfusate had no effect upon resting VIP release, but elevated CGRP and SP release significantly by 11.1 +/- 0.8 and 0.19 +/- 0.03 pg/mg/min over baseline release rate, respectively. Addition of dexmedetomidine (10 microM), an alpha 2-adrenergic agonist, did not change the baseline release of either CGRP or SP, but significantly decreased the CAP-evoked release of both peptides. The attenuation of the CAP-evoked release by the agonists was antagonized by the concurrent administration of yohimbine (10 microM) or atipamezole (10 microM), but not by prazosin. ST-91 (10 microM) did not alter the release of CGRP but decreased the CAP-evoked release of SP. This inhibition was antagonized by yohimbine and prazosin, but not by atipamezole. These data suggest that the afferent-evoked release of SP and CGRP from CAP-sensitive terminals (presumably those associated with small primary afferents) is modulated by local alpha 2 receptors. The common sensitivity of the agonists to yohimbine and the differential effects of atipamezole and prazosin are consistent with the hypothesis that dexmedetomidine and ST-91 may interact with different subpopulations of spinal alpha 2 receptors, both of which may modulate afferent terminal release.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of peptide- and tyrosine hydroxylase-containing neurons in the fetal spinal cord transplanted into the anterior chamber of the eye of adult rats

Fetal rat spinal cord transplanted into the anterior chamber of the eye of an adult rat was immunohistochemically stained using antisera to substance P (SP), neuropeptide Y (NPY), methionine-enkephalin (ENK), vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) and tyrosine hydroxylase (TH), and distributional changes of peptide- and enzyme-containing neurons 1, 2 and 4 weeks after transplantation were investigated. To examine the effect of colchicine on immunoreactivity, unilateral eyes of these adult host rats received intraocular colchicine treatment. Without colchicine treatment, numerous SP- and CGRP-immunoreactive (IR) neurons were observed in the graft 1 week after transplantation, and their immunoreactivity gradually decreased up to 4 weeks after transplantation. NPY-, ENK-and VIP-IR neurons first appeared in the graft 2 weeks after transplantation. Four weeks after transplantation, the immunoreactivity of NPY and ENK decreased significantly, whereas VIP-IR neurons showed the same intensity as that observed at 2 weeks after transplantation. TH-IR neurons, on the other hand, were seen at every stage, but their immunoreactivity was constant all the time. After colchicine treatment, the number of SP-, NPY-, ENK- and CGRP-IR neurons appeared to increase, while that of VIP- and TH-IR neurons did not change significantly. The distribution patterns of the peptide- and enzyme-containing fibers differed from each other. In the analysis of serial sections stained with 5 peptides (SP, NPY, ENK, VIP, CGRP), fibers containing these peptides were found to be densely accumulated in specific areas of the transplanted spinal cord. The present findings demonstrated that most of the peptide- and enzyme-containing neuron systems in the transplanted spinal cord showed similar distribution patterns and development to those in the normal spinal cord, but that some displayed different distribution.

The effects of A- and C-fiber stimulation on patterns of neuropeptide immunostaining in the rat superficial dorsal horn

The present study determines the effects of sciatic nerve stimulation at intensities that activate A-fibers alone or both A- and C-fibers on immunostaining for substance P (SP), cholecystokinin-octapeptide (CCK-8), galanin (GAL), dynorphin (DYN) and vasoactive intestinal polypeptide (VIP) in the superficial dorsal horn of the rat spinal cord. The goal of this study is to provide a more precise spatial localization of the sites of release or accumulation of these compounds in relation to specific types of stimuli. Following A-fiber stimulation, there was no significant change in immunostaining for any of these compounds. However, A- and C-fiber stimulation resulted in major changes. For SP, CCK-8, GAL and DYN there was a large and significant loss of immunostaining in medial regions of the dorsal horn. This is the area where sciatic nerve primary afferent fibers terminate and the depletion is probably correlated with activity in these fibers. By contrast, VIP immunostaining is increased in the lateral part of the superficial cord, which is outside of the central sciatic afferent fiber terminations. This indicates that the increase is not in the fine sciatic sensory axons that are directly stimulated. As a final point, the fact that C-fiber but not A-fiber stimulation causes marked changes in the immunocytochemical distribution of all these compounds is further evidence, albeit indirect, that they are involved in nociceptive information processing.

Morphological basis for back pain: the demonstration of nerve fibers and neuropeptides in the lumbar facet joint capsule but not in ligamentum flavum

The innervation of lumbar facet capsule and ligamentum flavum was investigated using antisera to a general neuronal marker protein gene product (PGP) 9.5 and to peptide markers of sensory nerves (calcitonin gene-related peptide [CGRP] and substance P) and autonomic nerves (vasoactive intestinal polypeptide [VIP] and C-flanking peptide of neuropeptide Y [CPON]). In the facet capsule (n = 14), PGP 9.5 and CGRP-immunoreactive nerves occurred in 12 and five specimens, respectively, both around blood vessels and as free fibers in the stroma. Free fibers immunoreactive for substance P or VIP were noted in three and five specimens, whereas in nine specimens there were CPON-immunoreactive nerves located perivascularly. There was no immunoreactivity in the ligamentum flavum. This study provides further evidence that the facet capsule but not the ligamentum flavum has substantial innervation by sensory and autonomic nerve fibers and has a structural basis for pain perception.

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.

Effect of adrenalectomy and dexamethasone on neuropeptide content of dorsal root ganglia in the rat

Neuropeptides, including substance P (SP), calcitonin gene-related peptide (CGRP) and somatostatin (SS) in dorsal root ganglia (DRG) may play a role in neurogenic inflammation and pain transmission. Adrenal corticosteroids regulate neuropeptide synthesis in some areas of the CNS and may modulate neurogenic inflammation and sensory perception. We have investigated the effects of adrenalectomy and dexamethasone (0.2 mg/kg/day) treatment on neuropeptide content of rat cervical DRG using specific and sensitive radioimmunoassays. In control animals, a differential distribution of neuropeptide was found; SP and CGRP content increased from C4 to C7 in contrast to SS content, which decreased from C4 to C7. Ten days following adrenalectomy, the mean SS content of cervical DRG decreased significantly to 79.6 +/- 4.5% of sham-operated controls. In contrast, SP and CGRP content increased significantly 10 days after adrenalectomy to 134.6 +/- 6.9% and 132.0 +/- 11.6% of sham-operated controls, respectively. The effects of adrenalectomy on CGRP and SS were reversed by administration of dexamethasone. These results suggest that glucocorticoids affect the neuropeptide content of DRG in the adult rat.

[125I]vasoactive intestinal polypeptide binding sites: quantitative autoradiographic distribution in the rat spinal cord

The quantitative autoradiographic distribution of [125I]vasoactive intestinal polypeptide (VIP) receptor binding sites was investigated in the rat spinal cord. [125I]VIP binding sites are discretely distributed, with a rostro-caudal gradient, along the longitudinal length of the cord; highest densities of sites being observed in its lumbar and sacral segments. In transverse sections, highest levels of [125I]VIP sites are present in laminae I and II, around the central canal, and in the parasympathetic lateral horn of the sacral segment. Moderate densities are seen along the medial border of the dorsal horn and the sympathetic lateral horn of the thoracic cord. Low amounts of labeling are observed in most structures of the ventral horn while white matter areas are apparently devoid of specific [125I]VIP binding. Thus, the distribution of spinal [125I]VIP receptor sites correlates well with that of VIP-like immunoreactive materials and support possible roles for this peptide in sensory neurotransmission and in the control of autonomic functions.

A large proportion of afferent neurons innervating the uterine cervix of the cat contain VIP and other neuropeptides

Axonal tracing techniques were used in combination with immunohistochemistry to examine the distribution of neuropeptides in afferent pathways from the uterine cervix of the cat. Primary afferent neurons innervating the uterine cervix were identified by axonal transport of the dye, fast blue, injected into the cervix. Fifteen to twenty-five days after the injection, dorsal root ganglia (L1-S3) were removed and incubated for 48-72 h in culture medium containing colchicine to increase the levels of peptides. Calcitonin gene-related peptide (CGRP), cholecystokinin (CCK), leucine-enkephalin (LENK), somatostatin, substance P and vasoactive intenstinal polypeptide (VIP) were identified by use of indirect immunohistochemical techniques. Eighty-four percent of uterine cervix afferent neurons were identified in the sacral dorsal root ganglia (S1-S3), and 16% in the middle lumbar dorsal root ganglia (L3-L4). In sacral dorsal root ganglia, VIP was present in the highest percentage of dye-labeled cells (71%), CGRP in 42%, and substance P in 18% of the cells. CCK and LENK were present in 13% of the cells. In lumbar dorsal root ganglia, CGRP (51%) was most prominent peptide followed by VIP (34%), substance P (28%), LENK (17%) and CCK (13%). Somatostatin was present in the ganglia but did not occur in dye-labeled neurons. In conclusion, the uterine cervix of the cat receives a prominent VIP- and CGRP-containing afferent innervation. The percentage of neurons containing VIP is three to five times higher than the percentage of these neurons in afferent pathways to other pelvic organs. These observations coupled with the results of physiological studies suggest that VIP is an important transmitter in afferent pathways from the cervix.

A quantitative study of neuropeptide immunoreactive cell bodies of primary afferent sensory neurons following rat sciatic nerve peripheral axotomy

Following peripheral axotomy, fluoride resistant acid phosphatase (FRAP) and most neuropeptides are depleted in the central terminals of axotomised nerves and reduced in their corresponding cell bodies (DRG) but vasoactive intestinal polypeptide (VIP) increases. The increase in VIP probably results from a change in gene expression in other ganglion cells which do not normally express VIP. A quantitative study was performed to investigate the proportion of DRG cells immunoreactive for different peptides at increasing times after sciatic nerve section. Retrograde fluorescent neuronal labelling of sciatic nerve cell bodies by injection of fast blue into the proximal stump was combined with unlabelled antibody immunohistochemistry for CGRP and VIP. The proportion of cells immunoreactive for these peptides was quantified between two and fourteen days post-axotomy. The number of VIP immunoreactive profiles increased significantly in the first 4 days post-axotomy, followed by a slight decrease before rising again. In contrast, the number of and CGRP-immunoreactive cell profiles declined to zero by 14 days post-axotomy. 4 days post-axotomy 50% of VIP positive cells were also immunoreactive for CGRP. There was neither colocalisation between VIP and FRAP nor between CGRP and FRAP. It is concluded that many peptidergic DRG cell bodies switch their expression of peptide to VIP after injury, whereas non-peptide-containing subpopulations do not.

Differential neuropeptide expression after visceral and somatic nerve injury in the cat and rat

The expression of neuropeptides galanin, vasoactive intestinal polypeptide (VIP) and substance P was compared after injury to somatic (sciatic, pudendal) and visceral (pelvic) nerves. Studies in normal rats and the mutant rat 'mutilated foot' suggested that galanin increases in sensory but not sympathetic fibres after sciatic nerve injury, while VIP appears to increase in both sensory and sympathetic fibres, and substance P to decrease in sensory fibres. A direct comparison of neuropeptide changes after somatic and visceral nerve injury was made in the cat dorsal sacral spinal cord, where both pudenal (somatic) and pelvic (visceral) afferents terminate. Four weeks after pudendal nerve transection in the cat there was an increase of VIP and galanin but decrease of substance P in the dorsal sacral cord, similar to the changes in lumbar dorsal cord after sciatic nerve section in the rat. In contrast, 4 weeks after pelvic nerve transection in the cat, galanin was unchanged in the ipsilateral dorsal sacral spinal cord, whereas VIP is known to decrease markedly and substance P to remain unchanged. There is thus differential peptide expression before and after injury in somatic and visceral systems, which may be regulated in part by the target organ. We have proposed that the neuropeptide changes occur in neurons that regulate development, maintenance and repair after injury, processes that may differ in somatic and visceral systems.

Do neuropeptides in the dorsal horn change if the dorsal root ganglion cell death that normally accompanies peripheral nerve transection is prevented?

Peripheral nerve section causes the death of dorsal root ganglion cells and changes in neuroactive peptides in the dorsal horn of the spinal cord. The relationship between these 2 events has not been previously studied, however. One approach would be to prevent sensory cell death and then determine changes in peptide immunoreactivity. To do this, transected rat sciatic nerve stumps were placed in an impermeable silicone tube for one month. The tube was then removed and after 30 additional days the cells were counted. The data indicate that no cell death occurred. We conclude that the sensory cells are first saved due to some factor present in the tube, and then after 30 days, the cells become independent of the tube and its contents. In these same animals, all of the peptides we examined were significantly changed. Four of the peptides, calcitonin gene-related peptide (CGRP), substance P (SP), cholecystokinin octapeptide (CCK) and galanin (GAL) were significantly depleted in the medial L4-L5 superficial dorsal horn, and vasoactive intestinal polypeptide (VIP) was significantly increased. We conclude that there are major changes in spinal peptide systems following peripheral nerve transection even if there is no accompanying death of sensory neurons. Thus we suggest that dramatic central changes in peptide immunoreactivity following peripheral nerve transection are independent of the sensory cell death that usually occurs in response to this injury.

An analogue of growth hormone releasing factor (GRF), (Ac-Try1, D-Phe2)-GRF-(1-29), specifically antagonizes the facilitation of the flexor reflex induced by intrathecal vasoactive intestinal peptide in rat spinal cord

The effect of intrathecal (i.t.) vasoactive intestinal peptide (VIP) and an analogue of growth hormone releasing factor (GRF) with putative VIP antagonistic property, (Ac-Try1, D-Phe2)-GRF-(1-29), on the nociceptive flexor reflex was studied in decerebrate, spinalized, unanesthetized rats. VIP (10 pM) facilitated the flexor reflex for several minutes. A similar facilitation was induced by the VIP antagonist applied i.t. with a potency 15 times less than that of VIP. Pre-administration of the VIP antagonist dose-dependently antagonized the reflex facilitation by i.t. VIP. In contrast, the reflex facilitation induced by i.t. substance P, somatostatin, calcitonin gene-related peptide and galanin was not influenced by the VIP-antagonist. The VIP antagonist by itself did not depress the flexor reflex over the dose range of 3 pM-3 nM and neither did it block the facilitation of the flexor reflex induced by a brief conditioning electrical stimulus train that activated the C-afferents in skin innervated by the sural nerve. The present results indicate that this GRF analogue is an effective and specific VIP antagonist in the rat spinal cord. Furthermore, it is suggested that VIP may not be involved in the transmission of cutaneous nociceptive information under normal conditions.

Evidence that some preganglionic sympathetic neurons in the rat contain vasoactive intestinal peptide- or peptide histidine isoleucine amide-like immunoreactivities

Physiological studies have established that preganglionic sympathetic nerve fibers innervating the rat superior cervical ganglion release a second transmitter, in addition to acetylcholine. Based on pharmacological and histochemical investigations, possible candidates for this non-cholinergic neurotransmitter include vasoactive intestinal peptide and peptide histidine isoleucine amide. For example, previous immunohistochemical studies have demonstrated that antisera raised against both of these peptides stain neural processes in the rat preganglionic cervical sympathetic trunk and in the superior cervical ganglion. In the present study, it was found that, when the cervical sympathetic trunk was ligated, vasoactive intestinal peptide- and peptide histidine isoleucine amide-like immunoreactivities built up on both sides of the ligature. In addition, examination of the thoracic spinal cord in colchicine-treated animals revealed vasoactive intestinal peptide- and peptide histidine isoleucine amide-like immunoreactivies in neuronal cell bodies in the intermediolateral cell column and in the region of the lateral funiculus adjacent to it. In a second group of animals in which retrograde tracing techniques were used, these two regions of the spinal cord were shown to contain most of the cell bodies of the preganglionic neurons that project to the superior cervical ganglion. Smaller numbers of retrogradely labeled neurons were found dorsal to the central canal and in the nucleus intercalatus. When either vasoactive intestinal peptide- or peptide histidine isoleucine amide-like immunostaining and retrograde labeling were examined in the same animals, double-labeled neurons were found in the intermediolateral cell column and in the lateral funiculus. These data demonstrate that vasoactive intestinal peptide- and peptide histidine amide-like immunoreactivities are present in certain of the preganglionic neurons that project to the superior cervical ganglion, supporting the hypothesis that vasoactive intestinal peptide and peptide histidine isoleucine amide are released in the ganglion when these preganglionic neurons are activated.

Studies of vasoactive intestinal polypeptide expression in injured peripheral neurons using capsaicin, sympathectomy and mf mutant rats

The increased expression of vasoactive intestinal polypeptide (VIP) in injured peripheral neurons was studied. In contrast to substance P, there was a marked increase, and maintained fast axonal transport, of VIP in rat sciatic nerve after peripheral axotomy. Local capsaicin application to the nerve trunk failed to inhibit the injury-induced VIP increase, and capsaicin even increased VIP levels when applied locally to uninjured nerves. Pharmacological sympathectomy showed that some of the peripheral VIP increase may occur in post-ganglionic sympathetic fibres. The VIP increase after injury appeared unaffected in the mf mutant rat, in spite of its loss of lumbar dorsal root ganglion cells. VIP-staining fibres in the epi- and peri-neurium and perivascular plexuses of sciatic nerve showed an increase in number in parallel with the changes of the nerve VIP content. These findings suggest that sensory and sympathetic nerve fibres expressing VIP after injury play a role in the regulation of blood flow to nerves, and in the pathophysiological processes in nerve and dorsal spinal cord which follow peripheral nerve injury.

Distribution and characterization of VIP-related peptides in the rat spinal cord

The possible existence in the rat spinal cord of a peptide related to VIP, VIP(22-28), has been evaluated. VIP contains paired basic aminoacid residues at which posttranslational cleavage of these peptides might occur. The lumbo-sacral region of rat spinal cord had the most VIP(22-28)-like immunoreactivity (ir-VIP(22-28]. Chromatographic analysis of spinal extracts showed that ir-VIP(22-28) consisted of two major peaks, one eluting as authentic VIP(1-28) and the other as VIP(22-28). HPLC confirmed these results, revealing the presence of intact VIP(1-28) and two or more less hydrophobic peptides, one of which corresponded to authentic VIP(22-28). The other two components found have not yet been identified. Further studies are necessary to provide information on the biological significance of VIP(22-28).

The calcitonin gene peptides: biology and clinical relevance

The calcitonin/CGRP multigene complex encodes a family of peptides: calcitonin, its C-terminal flanking peptide, katacalcin, and a third novel peptide, calcitonin gene-related peptide (CGRP). The 32-amino acid peptide calcitonin inhibits the osteoclast, thereby conserving skeletal mass during periods of potential calcium lack, such as pregnancy, growth, and lactation. This hormonal role is emphasized by observations that lower circulating calcitonin levels are associated with bone loss and that calcitonin replacement prevents further bone loss. Structurally, CGRP resembles calcitonin and has been implicated in neuromodulation and in the physiological regulation of blood flow. Here we review the molecular genetics, structure, and function of the calcitonin-gene peptides as analyzed in the laboratory and focus on more recent clinical studies relating to disorders and therapeutics.

Cardioacceleration provoked by intrathecal administration of vasoactive intestinal peptide (VIP): mediation by a non-central nervous system mechanism

Intrathecal administration of VIP to the thoracic spinal cord in the urethane anaesthetized rat provoked a dose-dependent increase in heart rate without any change in arterial pressure. The cardioacceleration observed following administration of 6.5 nmol of VIP at the T9 level (n = 8) occurred within 1-2 min of administration, with a peak effect of 70-85 bpm, 10-30 min after administration. The magnitude of the maximum change when this dose was given at the T2 level (n = 8) was approximately 100 beats per min, 7-8 min after administration. However, the differences between T2 and T9 administration were not statistically significant. Intravenous administration of 6.5 nmol of VIP (n = 6) mimicked the cardioacceleratory effect of intrathecal administration, and also decreased systolic and diastolic arterial pressure by 9-13 mmHg 6-13 min after administration. The cardioacceleration observed following intrathecal administration at T9 was not blocked by prior systemic administration of the autonomic ganglion blocker hexamethonium (5 mg/kg) or by bilateral vagotomy. Nor was the effect blocked by prior intrathecal administration of the local anaesthetic lidocaine (250 micrograms), although lidocaine did block the tachycardia and hypertension resulting from intrathecal administration of substance P. Considered collectively, the findings that the cardioacceleration observed following intrathecal VIP injection is mimicked by i.v. administration, is not reversed by blockade of nicotinic transmission of autonomic ganglia or by bilateral vagotomy, and is not blocked by lidocaine suggest that VIP's tachycardic effect does not result from a direct action on spinal mechanisms mediating autonomic control of the cardiovascular system, but occurs via diffusion to a site of action outside the central nervous system.

The new neuroanatomy of the spinal cord

In the last 2 decades, the application of new techniques in neuroanatomy has led to spectacular advances in our knowledge of the structure and function of the human spinal cord. In 1988, it is appropriate to review this progress, and I am grateful to Sir George Bedbrook and the organisers of the International Paraplegia Meeting in Perth, Western Australia, for inviting me to give this survey, to which I have given the title 'The New Neuroanatomy of the Spinal Cord'.

Vasoactive intestinal polypeptide (VIP) immunoreactivity in the ependymal cells of the rat spinal cord

Vasoactive intestinal polypeptide (VIP) was demonstrated immunohistochemically in the entire ependymal and subependymal cells in all levels (cervical: C, thoracic: T, lumbar: L and sacral: S) of normal adult rat spinal cord. The VIP-immunoreactive basal processes from the apical ependymal cells coursed dorsally or ventrally along the median plane and reached the pia mater of the dorsal and ventral median septa. Many VIP-immunoreactive basal processes terminated on the blood vessels in the neuropil around the central canal. A few microvilli of the ependymal cells that project into the central canal also demonstrated intense VIP immunoreactivity. These observations suggest that ependymal cells may be involved in the modulation of VIP levels in the cerebrospinal fluid and regulation of vascular tone of the blood vessels in the spinal cord.

Distribution of substance P and vasoactive intestinal polypeptide neurons in the chicken spinal cord, with notes on their postnatal development

The distribution of substance P (SP) and vasoactive intestinal polypeptide (VIP) was investigated by immunohistochemistry in the adult chicken spinal cord. By using colchicine treatment, populations of neurons containing either SP or VIP was observed in several regions of the spinal cord. SP neurons were found dorsal to the central canal (CC) and in lamina IV throughout the cord. However, at the thoracic level, numerous relatively larger SP perikarya were located ventral to the CC and aligned on either side of the midline. The distribution of SP fibers is very similar to that reported previously in mammals: they were mostly observed in laminae I and II, in Lissauer's tract, in the dorsolateral funiculus, and dorsal to the CC. In addition, two dense plexuses of SP fibers were noticed in lamina IV. VIP neurons were located mainly in lamina I, in the nucleus of the dorsolateral funiculus, and in the lateral portion of the neck of the dorsal horn throughout the spinal cord. At the thoracic level, many also were located lateral to the CC. Occasionally, single VIP neurons also were encountered dorsal to the CC, in laminae II-IV, and in the intermediate zone. VIP fibers were observed in similar numbers at all spinal levels, occurring mainly in laminae II (probably I) and III, dorsal to the CC, and in the intermediate zone. In addition, examination of the developing chick spinal cords showed similar results as in adult chickens.

Development and distribution of enkephalin-immunoreactive elements in the chicken spinal cord

The development and distribution of methionine-enkephalin-immunoreactive elements were studied in the chicken spinal cord with the indirect immunofluorescence method. Methionine-enkephalin-like immunoreactivity was first detected in the chick spinal cord at embryonic stages 29-30 (incubation day 6). Before stage 35 (day 9), it was mainly observed in fibres almost throughout the white matter. Subsequently, fibres containing the peptide appeared in the ventral half of the gray matter, but mostly in the lateral portion of the neck of the dorsal horn. From stage 40 (day 13 or 14), fibres were especially noticed in laminae 1 and 2, and in the area dorsal to the central canal. In particular, many enkephalin-immunoreactive perikarya were observed in several spinal areas during this period. Such a distribution of both enkephalin-immunoreactive fibres and perikarya remained visible at later embryonic stages, but labelled cells gradually decreased in number and disappeared after hatching. With colchicine treatment, however, a similar distribution of the peptide was found in the spinal cord of adult chickens. As in the embryo, enkephalin-immunoreactive perikarya were mainly observed in the lateral portion of the neck of the dorsal horn, in lamina 1, and in the nucleus of the dorsolateral funiculus throughout the spinal cord. At the thoracic level, many were also located ventral to the central canal. Enkephalin-immunoreactive fibres increased notably in the gray matter of adult chickens. They mainly occurred in laminae 1 and 2, in the lateral portion of the neck of the dorsal horn, and in the area around, especially dorsal to, the central canal. In contrast, enkephalin-immunoreactive fibres decreased in the white matter and they were mainly observed in the dorsolateral funiculus, in Lissauer's tract, and in the lateral funiculus adjacent to the gray. The distribution of enkephalin-immunoreactive fibres was generally comparable at all spinal levels examined. In addition, examination of post-hatched chickens showed virtually the same results as in the adult.

Expression of eight neuropeptides in intraocular spinal cord grafts: organotypical and disturbed patterns as evidenced by immunohistochemistry

The present study examines the distribution of several neuropeptides, as revealed by immunohistochemistry in the isolated cord. Fetal rat spinal cord was grafted to the anterior chamber of the adult Sprague-Dawley albino rats. After intraocular maturation for 2-3 months, the amount and distribution of somatostatin, neuropeptide Y, substance P, enkephalin, vasoactive intestinal peptide, peptide histidine-isoleucine, calcitonin gene-related peptide and cholecystokinin immunoreactive terminals and cell bodies were analysed using indirect fluorescence immunohistochemistry. The visualization of immunoreactive cell bodies in the grafts was enhanced using a novel intraocular colchicine treatment. In the graft a rich network of somatostatin-positive terminals was found with a high density in well-demarcated areas reminiscent of substantia gelatinosa of the dorsal horn of normal spinal cord. A large number of small- to medium-sized somatostatin neurons was found throughout the grafts without colchicine treatment. This is in contrast to normal spinal cord, where positive neurons were difficult to visualize without colchicine and were mainly confined to the dorsal horn. Neuropeptide Y had a distribution in the grafts similar to that of somatostatin and neuropeptide Y cells were found throughout the grafts without colchicine treatment. In normal spinal cord, neuropeptide Y-positive fibers were found mainly in substantia gelatinosa with a sparse network in the ventral horn. Enkephalin-positive fibers were found throughout the grafts. The distribution of fibers resembled that of somatostatin and neuropeptide Y with distinct zones of high fiber density in well-demarcated areas, whereas the density of nerve fibers in the rest of the graft neuropil was moderate to low. The distribution of substance P was similar to that of enkephalin. After colchicine treatment, both enkephalin- and substance P-positive cell bodies were visualized. In the intact spinal cord both peptides were seen in the entire gray matter with the highest concentrations in the superficial laminae of the dorsal horn. Antisera against calcitonin gene related-peptide, revealed a sparse terminal network and many large cells, which might represent motoneurons. A sparse network of varicose cholecystokinin-immunoreactive fibers was found evenly distributed in the grafts. In normal spinal cord a dense cholecystokinin-positive network of primary sensory afferent origin was found in the dorsal horn. In the grafts cholecystokinin cell bodies were seen after colchicine treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Distribution and development of VIP immunoreactive neurons in the spinal cord of the embryonic and newly hatched chick

The distribution and development of vasoactive intestinal polypeptide (VIP) immunoreactive elements were studied in the spinal cord of embryonic and newly hatched chicks with the indirect immunofluorescence method. VIP neurons were first detectable in the presumed dorsal horn at stages 27-28 (incubation day 5). Subsequently they increased in number, and by stage 39 (day 12) many occurred in lamina I, in the nucleus of the dorsolateral funiculus, and in the lateral portion of the neck of the dorsal horn throughout the cord. However, at the thoracic level many were also situated lateral to the central canal, with their processes running to the ipsilateral lateral and contralateral ventral funiculi. The pattern described above remained visible in both embryonic and colchicine-pretreated newly hatched chicks. During development, VIP fibers appeared later than cell bodies. In the gray matter, they were mainly scattered in the intermediate zone, especially around the central canal at all levels examined. In the white matter, however, longitudinal fibers were observed in the lateral funiculus throughout the cord, but mostly at the cervical level, though some also occurred in the ventral funiculus. This finding supports the idea that spinal VIP neurons might project rostrally via the lateral funiculus. In addition, no VIP immunoreactivity was found in the spinal ganglia, but examination of the sympathetic paravertebral ganglia showed immunoreactivity as described by others.

Effects of intrathecal administration of neuropeptides on a spinal nociceptive reflex in the rat: VIP, galanin, CGRP, TRH, somatostatin and angiotensin II

The present study examines the effects of intrathecal administration of selected peptides on nociceptive responses in the rat. Each peptide was delivered via a chronically implanted catheter to the L5 vertebral level. In the tail flick test, VIP (0.65-6.5 nmoles) produced a dose-dependent decrease in reaction time (RT) from 1 to 6-16 min after injection; 6.5 nmoles decreased RT to 37% of control value at 1 min after injection. Galanin (0.65-6.5 nmoles) produced a dose-dependent increase in reaction time at 1 and 6 min; at high doses, many of the rats failed to flick the tail. CGRP (6.5 nmoles) produced a small, transient decrease in RT to 73% of control values at 1 min; 3.25 nmoles were without effect. CSF and 6.5 nmoles of somatostatin, TRH and angiotensin II were without effect. At high doses of galanin and CGRP, rats vocalized to innocuous touch of the tail, as reported for substance P. Von Frey hairs were thus applied to the tail after 6.5 nmoles of VIP, galanin, CGRP or substance P. Vocalization in response to a previously innocuous pressure stimulus was observed at 30 s after injection in all rats given galanin and some rats given CGRP or substance P; the effect lasted 4-8 min. VIP and CSF had no effect. These results suggest that VIP, galanin, CGRP and substance P may act as excitatory agents in nociceptive pathways and that specific peptides may function in the different types of pain modalities; VIP in thermal, galanin in mechanical and substance P and CGRP in both.

Ontogeny of peptide- and amine-containing neurones in motor, sensory, and autonomic regions of rat and human spinal cord, dorsal root ganglia, and rat skin

The developmental patterns of neurofilament triplet proteins, peptide and amine immunoreactivities were compared in motor (ventral spinal cord), sensory (dorsal spinal cord, dorsal root ganglia, epidermis), and autonomic (intermediolateral cell columns, dermis) regions in the rat and human. In the rat, neurofilament triplet proteins first appeared in motoneurones (embryonic day 13). In the youngest human fetuses studied (6 weeks), immunoreactivity was present throughout the spinal cord. Peptides and amines occurred later. Calcitonin gene-related peptide, galanin, somatostatin, neuropeptide Y and its C-flanking peptide (CPON) were the first to appear localized to motoneurones (embryonic days 15-17 rat; fetal weeks 6-14 human). Numbers of immunoreactive motoneurones decreased toward birth, but immunoreactive fibers increased in the ventral horn with enkephalin, thyrotrophin-releasing hormone, and the monoaminergic markers 5-hydroxytryptamine and tyrosine hydroxylase (all presumably of supraspinal origin) the last to appear perinatally. In the dorsal horn, particularly in the rat, a transient expression of substance P-, somatostatin-, and neuropeptide Y/CPON-immunoreactive cells was detected (embryonic days 15-17). A pronounced increase of calcitonin gene-related peptide-, galanin-, somatostatin- and substance P- immunoreactive fibers was found perinatally in both species. This coincided with an increased detection of cells in the dorsal root ganglia containing these peptides and the earliest appearance of calcitonin gene-related peptide-, somatostatin-, and substance P-immunoreactive fibers in the rat epidermis. Few antigens were localized to the intermediolateral cell columns before embryonic day 20 (rat), fetal week 20 (human), with thyrotrophin-releasing hormone-, 5-hydroxytryptamine-, tyrosine hydroxylase-, and vasoactive intestinal polypeptide-immunoreactive nerves appearing perinatally. In the rat dermis, tyrosine hydroxylase-immunoreactive fibers (sympathetic fibers) and fibers immunoreactive for neuropeptide Y/CPON and vasoactive intestinal polypeptide were detected from postnatal day 1. In conclusion, 1) peptide and amine immunoreactivity develops in motor before sensory or autonomic regions, 2) many peptide-containing cells are transient in fetal life, and 3) central terminals of dorsal root ganglion cells express peptides before terminals in the skin.

Immunocytochemical identification of long ascending peptidergic neurons contributing to the spinoreticular tract in the rat

In the present study, we examined the peptidergic content of lumbar spinoreticular tract neurons in the colchicine-treated rat. This was accomplished by combining the retrograde transport of the fluorescent dye True Blue with the immunocytochemical labeling of neurons containing cholecystokinin-8, dynorphin A1-8, somatostatin, substance P or vasoactive intestinal polypeptide. After True Blue injections into the caudal bulbar reticular formation, separate populations of retrogradely labeled cells were identified as containing cholecystokinin-like, dynorphin-like, substance P-like or vasoactive intestinal polypeptide-like immunoreactivity. Retrogradely labeled somatostatin-like neurons were not identified in any of the animals examined. Each population of double-labeled cells showed a different distribution in the lumbar spinal cord. The highest yield of double-labeling occurred for cholecystokinin, with 16% of all intrinsic cholecystokinin-like neurons containing True Blue. These double labeled neurons were found predominantly at the border between lamina VII and the central canal region. About 11% of intrinsic vasoactive intestinal polypeptide-like neurons in the lumbar spinal cord were retrogradely labeled from the bulbar reticular formation. These neurons were found mostly in the lateral spinal nucleus, with only a few double-labeled cells located deep in the gray matter. Dynorphin-like double-labeled neurons were localized predominantly near the central canal; a smaller population was also seen in the lateral spinal nucleus. It was found that double-labeled dynorphin-like neurons made up 8% of all intrinsic dynorphin-like neurons. Retrogradely-labeled substance P-like neurons were rare; the few double-labeled neurons were found in the lateral spinal nucleus and lateral lamina V. These findings suggest a significant role for spinal cord peptides in long ascending systems beyond their involvement in local circuit physiology.

Analysis of peptide histidine-isoleucine/vasoactive intestinal polypeptide-immunoreactive neurons in the central nervous system with special reference to their relation to corticotropin releasing factor- and enkephalin-like immunoreactivities in the paraventricular hypothalamic nucleus

The distribution of peptide histidine-isoleucine (PHI) and vasoactive intestinal polypeptide (VIP), two peptides derived from the same precursor molecule, was analysed with immunohistochemistry in the central nervous system of the rat, and to a limited extent in some other species including sheep, monkey and man. Special attention was focused on possible cross-reactivity between PHI antisera and corticotropin releasing factor in parvocellular neurons in the hypothalamic paraventricular nucleus projecting to the external layer of the median eminence. (1) Characterization of the PHI and VIP antisera revealed that they recognized different sequences of the peptide molecules. One of the PHI antisera (PHI-N), although mainly N-terminally directed, also probably contained an antibody population directed against the C-terminal amino acid in PHI which is an amidated isoleucine. Rat and human corticotropin releasing factor but not ovine also have an amidated isoleucine in C-terminal position. (2) PHI- and VIP-like immunoreactivity were found with parallel and overlapping distribution in all areas investigated in the rat central nervous system. In many cases coexistence of the two immunoreactivities could be directly demonstrated. PHI neurons were found in some areas so far not know to contain PHI/VIP neurons, including the dorsal septum, the septofimbrial nucleus, the stria terminalis and lamina V of the spinal cord. (3) Using an antiserum directed against the amino acid sequence 111-122 of the VIP/PHI precursor, immunoreactive cell bodies were seen in some areas containing VIP and PHI neurons. PHI- and VIP-like immunoreactivity were expressed in parallel in increasing amounts in the superficial laminae of the dorsal horn after transection of the sciatic nerve [G. P. McGregor et al. (1984) Neuroscience 13, 207-216; S. A. S. Shehab and M. E. Atkinson (1984) J. Anat. 139, 725; S. A. S. Shehab and M. E. Atkinson (1986) Expl Brain Res. 62, 422-430]. (5) The PHI-N antiserum stains large numbers of immunoreactive cells in the parvocellular part of the paraventricular nucleus and these cells are mostly identical with corticotropin releasing factor-positive neurons. Absorption experiments suggested that this PHI-N-like immunoreactivity to a large extent represented cross-reactivity with rat CRF and that earlier demonstration of many PHI-positive neurons in the paraventricular nucleus probably represents an artefact as proposed by F. Berkenbosch et al. (Neuroendocrinology 44, 338-346). However, some cells did, in fact, contain VIP- as well as PHI-like immunoreactivity as was shown with antisera not cross-reacting with corticotropin releasing factor.(ABSTRACT TRUNCATED AT 400 WORDS)

Intrathecal vasoactive intestinal polypeptide modulates spinal reflex excitability primarily to cutaneous thermal stimuli in rats

The effect of intrathecally (i.t.) injected vasoactive intestinal polypeptide (VIP) on spinal nocifensive flexor reflex excitability was examined in decerebrate, spinalized, unanesthetized rats. The hamstring reflex was evoked by intense cutaneous mechanical or thermal stimulation of the ipsilateral foot. I.t. VIP increased the excitability of the spinal cord to thermal much more than to mechanical stimuli. It is suggested that this neuropeptide is released by thermosensitive cutaneous afferents that respond poorly to mechanical stimuli.