Stimulation of connective tissue cell growth by substance P and substance K

Involvement of capsaicin-sensitive nerves in paraquat-induced mortality

Paraquat (PQ), a broad spectrum herbicide, produces severe lung inflammation and necrosis resulting in pulmonary fibrosis and respiratory failure. Tachykinins are peptides released by sensory C fibers and have the ability of influencing respiratory functions and cellular proliferation. To examine whether the damage caused by PQ involves tachykinins, rats were depleted in their content of tachykinins by systemic treatment with capsaicin prior to PQ exposure. The animal subjected to this treatment showed a 3-fold higher viability compared to those treated with PQ alone (75 vs 27%). Depletion of reduced glutathione (GSH) is associated with oxidative stress produced by reactive oxygen intermediates during PQ metabolism. This is considered to be critical in the pathogenesis of lung damage by PQ. PQ treatment induced a significant depletion of GSH during the first days and a similar effect was also observed in the group of capsaicin-pretreated rats. Four weeks after PQ treatment the levels of GSH were similar to controls in rat pretreated or not with capsaicin plus PQ. This may indicate that the reduced levels of GSH may be associated to the toxicity observed in the acute phase, but not of importance in the final PQ-induced mortality. Neutral endopeptidase (NEP) is an enzyme considered to be critical in controlling the levels of tachykinins. Exposure of crude membrane preparations of rat lung to PQ resulted in a dose-dependent inhibition of NEP activity. Since NEP inactivation may occur in lung following a PQ exposure in vivo, the results indicate that during PQ intoxication a more sustained activity of tachykinins may be present, producing effects such as cell proliferation, fluid extravasation and bronchoconstriction. In conclusion, this finding supports the hypothesis that neuropeptides released from capsaicin-sensitive nerves could be involved in the modulation of PQ-induced lung damage.

Antioxidants attenuate chronic hypoxic pulmonary hypertension

Because chronic hypoxia increases the production of oxygen radicals, we hypothesized that antioxidants attenuate chronic hypoxic pulmonary hypertension. In part 1, we examined the temporal progress in chronic hypoxic pulmonary hypertension in 46 Wistar rats exposed to hypoxia from 0-3 weeks. In part 2, we tested whether antioxidants attenuated chronic hypoxic pulmonary hypertension in 82 rats divided into 10 groups: control, fullerenol-1, U-83836E, dimethylthiourea-1, dimethylthiourea-2, hypoxia, hypoxia + fullerenol-1, hypoxia + U83836E, hypoxia + dimethylthiourea-1, and hypoxia + dimethylthiourea-2. Control animals breathed room air and were injected intraperitoneally with saline for 2 weeks. Fullerenol-1, U-83836E, and dimethylthiourea are antioxidants and were administered intraperitoneally for 2 weeks, except that dimethylthiourea was given either on days 3, 5, and 7 (dimethylthiourea-1), or on days 8, 10, and 12 (dimethylthiourea-2). Hypoxic animals were placed into a hypobaric chamber with a barometric pressure of 380 Torr for 2 weeks. Hypoxia + antioxidant groups were administered antioxidants during hypoxic exposure. We observed a gradual increase in pulmonary artery pressure, the weight ratio of right ventricle to left ventricle plus septum, and hematocrit during the 3 weeks of chronic hypoxia. These hypoxia-induced alterations were significantly attenuated by U-83836E and dimethylthiourea, but not by fullerenol-1. Neither the temporal alterations nor the antioxidant effects can be explained by the change in either tracheal neutral endopeptidase activity or the lung or plasma substance P level, perhaps because of the time lag in sampling. These results indicate that oxygen radicals play an important role in the development of chronic hypoxic pulmonary hypertension.

Signal transduction in wound pharmacology

Growth factors such as TGF-beta, PDGF and FGF are thought to play important roles in wound healing. However, their biological activity and signal transduction during wound repair remain poorly understood. Growth factors are often ligands for receptor tyrosine kinase and receptor serine/threonine kinases. With recent advances in signal transduction by receptor kinases, we are beginning to understand the underlying mechanism of how growth factors may regulate cutaneous wound repair. In this paper, we will describe the pharmacological effects of growth factors on wound healing, and discuss the potential underlying signaling mechanisms. Thus, we hope to provide the basis for designing more specific therapeutics for wound healing in the near future.

Sensory nerves affect the recruitment and differentiation of rat periovarian brown adipocytes during cold acclimation

Rat periovarian adipose tissue contains a low number of uncoupling protein-expressing brown adipocytes scattered into lobules of white fat. Their increase following cold acclimation is matched by a major increase in noradrenergic and neuropeptide Y-, substance P- and calcitonin gene-related peptide-containing nerves. To ascertain whether periovarian fat is provided with sensory nerves, and whether any relationship exists between such nerves (in particular the calcitonin gene-related peptide-containing fibers found in cold-acclimated rats in close association with brown adipocytes) and brown fat recruitment, the effects of capsaicin desensitization on neuropeptide-containing nerves and brown adipocyte density were studied in the periovarian tissue of rats kept at 20 degrees C and on a group acclimated to 4 degrees C for 14 days. In both groups, systemic capsaicin administration considerably reduced the expression of substance P and calcitonin gene-related peptide in vascular-nerve bundles and parenchyma. In cold-acclimated rats, the increase in brown adipocyte density was significantly checked by capsaicin administration (21.11 versus 7.96 brown adipocytes/mm2, P<0.05). Finally, ultrastructural investigation showed the occurrence of brown adipocyte precursors filled with aggregates of glycogen and poorly differentiated multilocular adipocytes in capsaicin-treated cold-acclimated rats. These data suggest that periovarian adipose tissue is indeed provided with sensory neuropeptide-containing nerves and that they play a role in the recruitment and differentiation of brown adipocytes.

Distribution of calcitonin gene-related peptide, somatostatin, substance P and vasoactive intestinal polypeptide in experimental colitis in rats

Immunohistochemistry was used to examine the distribution of calcitonin gene-related peptide (CGRP), substance P, somatostatin and vasoactive intestinal polypeptide (VIP) in experimental colitis induced with trinitrobenzene sulphonic acid (TNBS) in rats. CGRP immunoreactivity was observed throughout the colonic wall. A significant reduction of CGRP-immunoreactive (IR) nerve fibres was observed in the mucosa after the induction of colitis. After TNBS treatment substance P immunoreactivity was reduced throughout the colon; however, after 7 days there was a marked re-innervation of the circular muscle. Somatostatin immunoreactivity was distributed sparsely within the colonic wall, and was comparatively less affected by colitis. VIP immunoreactivity was abundantly distributed in the colonic wall and underwent an immediate reduction in the mucosa after TNBS treatment. After 2 days, there was a consistent and progressive increase in the number and density of VIP-IR nerve fibres in the inflamed colon, particularly the circular muscle. This change was associated with a proliferation of nerve fibres within the muscle layers. It was concluded that the early decrease in these neuropeptides was consistent with release from peripheral nerve terminals or the loss of nerves during the initial stages of colonic inflammation, which may be an essential condition for the development of colitis in this model. The observation that the intensity and density of substance P and VIP-IR nerve fibres increased in the circular muscle 7 days after the induction of colitis suggests their possible involvement in tissue repair.

Serotonin and neuroendocrine peptides influence DNA synthesis in rat and human small intestinal cells in vitro

Animal studies suggest a mediator role for neuroendocrine peptides and amines in regulating cell proliferation in the gastrointestinal epithelium. Our aim was to examine the effect of serotonin and selected gastrointestinal peptides on DNA synthesis in a rat and human small intestinal cell line in vitro. IEC-6 and FHs-74 cells were incubated with epidermal growth factor (EGF), insulin-like growth factor II, glucagon, substance P, neurokinin A, calcitonin gene-related peptide (GRP, CCGRP), neurotensin and serotonin. The cells were labelled with [methyl-3H] thymidine and processed for autoradiography. DNA synthesis was evaluated by the labelling index. Epidermal growth factor, insulin-like growth factor II, glucagon, and substance P increased the labelling index in a dose-related manner (P < 0.003). In contrast, a significant dose-dependent reduction of the labelling index was observed after administration of serotonin and neurokinin A (P < 0.0001). Neurotensin and CGRP did not affect the labelling index. EGF, insulin-like growth factor II, glucagon, substance P, serotonin and neurokinin A may be important physiological regulators of proliferation, of gastrointestinal cells.

A possible role for saliva as a diagnostic fluid in patients with chronic pain

OBJECTIVES

The focus of this review was on proteins and peptides found in saliva. Of greatest interest were those neuropeptides relevant to nociception and to the pathogenesis of chronic pain syndromes. An additional goal was to develop a standardized protocol to collect saliva for laboratory assessment.

METHODS

Data were obtained through discussion with experts at the medical schools in San Antonio and Heidelberg and a Medline literature search involving all relevant studies from 1966 to 1997. The literature search was based on the following key terms: saliva, serotonin, neuropeptide, substance P (SP), calcitonin gene-related peptide (CGRP), and nerve growth factor (NGF).

RESULTS

The mean concentration of SP in the saliva of healthy normal controls ranged from 9.6 to 220 pg/mL. Generally, the concentration of SP was approximately three times higher in saliva than in plasma. In a number of painful conditions, particularly tension headache, substantial elevations of salivary SP were found. Mean values for salivary CGRP in healthy controls were approximately 22 pmol/L and were significantly elevated in patients with migraine attacks or cluster headache. There were no data to indicate prior quantitative determination of NGF in human saliva.

CONCLUSIONS

After sampling and processing techniques have been standardized, measurement of neuropeptides in human saliva could provide a valuable tool for study of patients with chronic painful disorders such as rheumatoid arthritis, osteoarthritis, and even fibromyalgia syndrome.

Neuroimmunomodulation in inflammatory bowel disease. How far from "bench" to "bedside"?

The chronic inflammatory bowel diseases (BID), Crohn's disease and ulcerative colitis, are characterized by recurrent periods of inflammation and tissue destruction. The clinical course is influenced by genetics, environmental factors, and the immune system. Recent insights (bench trials) benefiting from advances in genetic engineering and molecular biology have contributed to clinical care (bedside) in terms of actual or potential therapies. Does the neuroendocrine system significantly modify disease activity? Although conceptually appealing, evidence remains circumstantial. Compelling anecdotal reports exist that "stress" affects disease activity in terms of the frequency and severity of IBD flares (bedside), but the mechanisms underlying these observations are unknown. Evidence that neuroendocrine factors play a significant role in immunomodulation is progressing (bench). (i) Trinitrobenzene sulfonic acid (TNB)-induced colitis, although similar in unstressed Fisher and Lewis rats, shows marked worsening in stressed Lewis rats. (ii) Early studies of rectal pain perception suggest there are specific differences in neuroimaging studies (PET scans) in IBD patients compared to controls. (iii) Levels of substance P (SP) and its receptor are altered. (iv) Preliminary clinical studies with SP receptor antagonists show a trend toward improvement. (v) Importantly, the placebo response in clinical trials is as high as 45%. Evidence that neuroendocrine systems significantly modulate local inflammation is rapidly accumulating (bench), which will facilitate enhanced coordination of clinically relevant therapies (bedside).

Peptidergic innervation of the rat cornea

Corneal nerves regulate corneal epithelial integrity, proliferation, and wound healing. The mechanisms by which the nerves mediate their effects remain poorly understood; however, the release of biologically active neuropeptides has been hypothesized. The purpose of the current investigation was to determine the relative densities, distribution patterns, and origins of rat corneal nerves containing each of eight different neuropeptides, calcitonin gene-related peptide (CGRP), substance P (SP), galanin (GAL), neuropeptide Y (NPY), methionine-enkephalin (M-ENK), vasoactive intestinal polypeptide (VIP), somatostatin (SOM), and cholecystokinin (CCK). In the first set of experiments, immunohistochemical demonstrations of the above neuropeptides were performed on free-floating corneal sections cut tangential to the corneal surface. The results showed that six of the peptides, CGRP, SP, GAL, NPY, M-ENK, and VIP were present in rat corneal nerves. The innervation patterns of corneal nerves containing each of these six peptides were then documented by mapping all fibers in serial sections from select corneal quadrants onto a series of line drawings by using a drawing tube. In the second set of experiments, the origins of the corneal peptidergic nerve fibers were determined by selective ocular denervations. Unilateral combined sensory and sympathetic ocular denervations or unilateral sympathetic ocular denervations were performed in adult rats by transecting the ophthalmomaxillary nerve and/or removing the superior cervical ganglion. After 5-7 days, each of the ipsilateral corneas was sectioned and processed immunohistochemically for the presence of one of the six peptides found in experiment one, and the fibers that survived the ocular denervations were plotted onto line drawings. Ocular denervations revealed that corneal peptidergic nerves have sensory (CGRP, SP, and GAL), sympathetic (NPY), and parasympathetic (GAL, NPY, M-ENK, and VIP) origins. The results of this investigation have shown that the peptidergic innervation of the rat cornea is more extensive and complex than previously reported. This is the first investigation to show the presence of GAL in the rat cornea, and the first to demonstrate the presence of NPY-, VIP-, and M-ENK-IR nerve fibers in the cornea of any species.

Neuropeptides in the skin: interactions between the neuroendocrine and the skin immune systems

The interaction between components of the nervous system and multiple target cells in the cutaneous immune system has been receiving increasing attention. It has been observed that certain skin diseases such as psoriasis and atopic dermatitis have a neurogenic component. Neuropeptides released by sensory nerves that innervate the skin and often contact epidermal and dermal cells can directly modulate functions of keratinocytes, Langerhans cells (LC), mast cells, dermal microvascular endothelial cells and infiltrating immune cells. Among these neuropeptides the tachykinins substance P (SP) and neurokinin A (NKA), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and somatostatin (SOM) have been reported to effectively modulate skin and immune cell functions such as cell proliferation, cytokine production or antigen presentation under physiological or pathophysiological conditions. Expression and regulation of their corresponding receptors that are expressed on a variety of skin cells as well as the presence of neuropeptide-specific peptidases such as neutral endopeptidase (NEP) or angiotensin-converting enzyme (ACE) determine the final biological response mediated by these peptides on the target cell or tissue. Likewise, skin cells like keratinocytes or fibroblasts are a source for neurotrophins such as nerve growth factor that are required not only for survival and regeneration of sensory neurons but also to control responsiveness of these neurons to external stimuli. Therefore, neuropeptides, neuropeptide receptors, neuropeptide-degrading enzymes and neurotrophins participate in a complex, interdependent network of mediators that modulate skin inflammation, wound healing and the skin immune system. This review will focus on recent studies demonstrating the role of tachykinins, CGRP, SOM and VIP and their receptors and neuropeptide-degrading enzymes in mediating neurogenic inflammation in the skin.

The tachykinin NK1 receptor. Part II: Distribution and pathophysiological roles

The tachykinin NK1 receptor is widely distributed in both the central and peripheral nervous system. In the CNS, NK1 receptors have been implicated in various behavioural responses and in regulating neuronal survival and degeneration. Moreover, central NK1 receptors regulate cardiovascular and respiratory function and are involved in activating the emetic reflex. At the spinal cord level, NK1 receptors are activated during the synaptic transmission, especially in response to noxious stimuli applied at the receptive field of primary afferent neurons. Both neurophysiological and behavioural evidences support a role of spinal NK1 receptors in pain transmission. Spinal NK1 receptors also modulate autonomic reflexes, including the micturition reflex. In the peripheral nervous system, tachykinin NK1 receptors are widely expressed in the respiratory, genitourinary and gastrointestinal tracts and are also expressed by several types of inflammatory and immune cells. In the cardiovascular system, NK1 receptors mediate endothelium-dependent vasodilation and plasma protein extravasation. At respiratory level, NK1 receptors mediate neurogenic inflammation which is especially evident upon exposure of the airways to irritants. In the carotid body, NK1 receptors mediate the ventilatory response to hypoxia. In the gastrointestinal system, NK1 receptors mediate smooth muscle contraction, regulate water and ion secretion and mediate neuro-neuronal communication. In the genitourinary tract, NK1 receptors are widely distributed in the renal pelvis, ureter, urinary bladder and urethra and mediate smooth muscle contraction and inflammation in response to noxious stimuli. Based on the knowledge of distribution and pathophysiological roles of NK1 receptors, it has been anticipated that NK1 receptor antagonists may have several therapeutic applications at central and peripheral level. At central level, it is speculated that NK1 receptor antagonists could be used to produce analgesia, as antiemetics and for treatment of certain forms of urinary incontinence due to detrusor hyperreflexia. In the peripheral nervous system, tachykinin NK1 receptor antagonists could be used in several inflammatory diseases including arthritis, inflammatory bowel diseases and cystitis. Several potent tachykinin NK1 receptor antagonists are now under evaluation in the clinical setting, and more information on their usefulness in treatment of human diseases will be available in the next few years.

Cutaneous wounds produced by capsaicin treatment of newborn rats are due to trophic disturbances

The purpose of this study was to show that the occurrence of skin ulcers observed in animals neonatally treated with the neurotoxin capsaicin coincide with trophic disturbances. In addition, cutaneous lesions increased when self-grooming and scratching behaviors reached maturity. The temporal course of cephalic cutaneous wounds in neonatally capsaicin-treated rats was evaluated in animals wearing and not wearing plastic collars from postnatal day (P) 21 until P45. The collars were used to prevent self-grooming and scratching. Beginning on P21, capsaicin-treated rats under both conditions showed transient skin ulcers distributed throughout the head and neck regions. In the capsaicin-treated group without collars, lesions reached their greatest severity by P40, when self-grooming and scratching behaviors obtained adult characteristics. Furthermore, no lesions were detected after 25 days. In the capsaicin-treated rats that wore plastic collars, the widest distribution of skin lesions occurred on P55, after which time lesions vanished detection by 25 days. In this latter group, the cutaneous lesions were exacerbated when collars were removed. Data suggest that transient cutaneous wounds associated with neonatal capsaicin administration may be mediated via capsaicin-sensitive sensory neurons that are involved in trophic and regenerating neural mechanisms.

Change in substance P in a firearm wound and its significance

The present study was designed to detect the change of substance P (SP) in firearm wounds and its relationship with wound healing. Twenty two rabbits were randomly divided into two groups, one with firearm wounds created by steel balls shooting rabbits' thighs and another with stab wounds created by knife. The experimental design did not include direct injury to femora major peripheral nerve trunks or blood vessels. SP content in wound tissue of both groups was measured with radioimmunoassay (RIA). Histologic examination was performed on the wound and the saphenous and sciatic nerves away from the wound-track edges. It was found that both types of injuries caused an increase of SP content in the wound compared with normal tissue. At three to 10 days after injury, SP content was lower in firearm wounds than that in stab wounds. Pathomorphologic observation showed the indirect injuries to the saphenous and sciatic nerves in the rabbits with firearm wounds were more severe than those with stab wounds. Meanwhile, wound healing in the firearm wounds was poor compared with that in the stab wounds. The results suggest that the change in SP in firearm wounds differs from that in cold weapon wounds as a result of the presence of indirect injuries to major peripheral nerve trunks created by laceration shock wave and cavity effects, and SP in vivo may participate in wound healing as a growth factor. Therefore, the improvement of neuropeptide metabolism in firearm wound may be an important measure for accelerating wound healing.

Substance P and neurokinin A in gingival crevicular fluid in periodontal health and disease

The aims of the present study were to investigate whether the tachykinins substance P and neurokinin A were present in gingival crevicular fluid in both periodontal health and disease and to study the relationship with periodontal inflammation. Gingival crevicular fluid (GCF) was collected from a healthy, a gingivitis and a periodontitis site in 20 subjects with periodontitis and from a healthy site in 20 subjects without periodontitis. The volume of GCF was measured and each sample subsequently analysed for substance P and neurokinin A by radioimmunoassay. There were significantly increased levels of substance P-like immunoreactivity (SP-LI) and neurokinin A-like immunoreactivity (NKA-LI) in gingivitis and periodontitis sites compared with healthy sites. Both tachykinins were significantly elevated in periodontitis affected subjects, with significantly more tachykinin-like immunoreactivity at healthy sites in periodontitis affected compared with periodontally-healthy subjects. Despite the considerable individual variation in the levels of SP-LI and NKA-LI, both tachykinins were present at levels at which they could have biological activity. It is concluded that substance P and neurokinin A may have a rôle in the pathogenesis of periodontal disease and that further investigations could prove useful in clarifying the mechanisms through which neuropeptides could modulate periodontal health and disease.

Magnesium deficiency enhances oxidative stress and collagen synthesis in vivo in the aorta of rats

Magnesium deficiency has been shown to produce vascular lesions in experimental animals, but the underlying mechanisms of vascular injury are not clear. It has been reported that in rodents, magnesium deficiency enhances circulating levels of factors that promote free radical generation and are mitogenic. In pursuance of these observations, the present study tested the hypothesis that magnesium deficiency may enhance oxidative stress and trigger an accelerated growth response in vivo in the aorta of rats. Oxidative stress was evaluated in terms of levels of thiobarbituric acid-reactive substances in the serum and aorta and activity of superoxide dismutase and catalase in the aorta; fractional rates of collagen synthesis were assessed using [3H]-proline. Serum and tissue levels of magnesium and calcium were determined by atomic absorption spectrophotometry. The present study demonstrated for the first time that magnesium deficiency significantly (P < 0.001) increases levels of thiobarbituric acid-reactive substances in the aorta of rats. Other changes in the aorta of animals on the Mg-deficient diet included a significant reduction (54%, P < 0.001) in the activity of superoxide dismutase and catalase (37%, P < 0.01) and a 19% increase in net fractional rates of collagen synthesis (P < 0.05). While serum magnesium was significantly reduced in these animals (P < 0.001), aortic tissue levels of magnesium in these animals remained unaltered throughout the duration of the study, suggesting the existence of other control mechanisms, apart from reduced tissue levels of magnesium, mediating the observed effects. These findings suggest that magnesium deficiency may trigger a wound healing response, involving oxidative injury and growth stimulation, in the vascular system.

Sensory neuropeptides: their role in inflammation and wound healing

Vasoactive neuropeptides including substance P and calcitonin gene-related peptide (CGRP) are localised in sensory nerves which innervate blood vessels. These are the major vasoactive neuropeptides released from sensory nerve endings and both have been suggested to have roles in inflammatory and cardiovascular disease. The neuropeptides have potent effects on microvascular tone and permeability, which are seen soon after release from perivascular nerves. There is also evidence that neuropeptides can affect various activities of inflammatory cells and that sensory nerves play a role in the recovery of the healthy microcirculation during wound healing phases. This review concentrates on evidence that the neuropeptides substance P, acting via tachykinin NK1 and NK2 receptors, and CGRP, acting via CGRP1 receptors, play a pro-inflammatory role in disease and a beneficial role in wound healing. In addition, results from clinical trials of recently developed neuropeptide antagonists are discussed.

Tachykinin NK1 and NK2 receptors mediate non-adrenergic non-cholinergic excitatory neuromuscular transmission in the guinea-pig stomach

By using selective tachykinin NK1 and NK2 receptor antagonists and agonists, we studied the excitatory non-adrenergic non-cholinergic transmission to the circular muscle of the corpus of guinea-pig stomach by the sucrose-gap method. After elimination of inhibitory junction potentials by apamin (0.1 microM), L-nitroarginine (30 microM) and tetraethylammonium (10 mM), electrical field stimulation (10 Hz) in the presence of atropine (1 microM) and nifedipine (1 microM) evoked a pure excitatory junction potential and contraction. The selective tachykinin NK2 receptor antagonist, MEN 11420, concentration-dependently inhibited the non-adrenergic non-cholinergic excitatory junction potential (EC50=0.09 microM) and contraction (EC50=0.04 microM) evoked by electrical field stimulation. On the other hand, the selective NK1 receptor antagonist GR 82334 (3 microM) only slightly (by about 30%) inhibited the excitatory junction potential while leaving the contraction unaffected. The combined administration of GR 82334 (1 microM) and MEN 11420 (0.3 microM) produced an additive inhibition of the excitatoryjunction potential, significantly larger than that produced by each antagonist alone. In the presence of both GR 82334 (1 microM) and MEN 11420 (0.3 microM), the P2 purinoreceptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (30 microM) remarkably inhibited the fast component of the excitatory junction potential. In the presence of atropine (1 microM), indomethacin (3 microM) and guanethidine (3 microM) either the selective NK2 receptor agonist, [betaAla8]neurokinin A (4-10) (0.01 microM), or the selective NK1 receptor agonist, [Sar9]substance P sulfone (0.3 microM), produced tetrodotoxin-(1 microM) and nifedipine-(1 microM) resistant depolarization and contraction. The [Sar9]substance P sulfone (0.3 microM)-induced contraction, but not that induced by [betaAla8]neurokinin A (4 10) (0.01 microM), was potentiated by apamin (0.1 microM) plus L-nitroarginine (30 microM). In the presence of atropine (1 microM), indomethacin (3 microM), guanethidine (3 microM), apamin (0.1 microM) and L-nitroarginine (30 microM), the selective tachykinin NK2 and NK1 receptor agonists, [betaAla8]neurokinin A (4-10) and [Sar9]substance P sulfone, both produced a concentration-dependent depolarization and contraction of the circular muscle. MEN 11420 inhibited the responses to [[Ala8]neurokinin A (4-10) without affecting the responses to [Sar9]substance P sulfone, while GR 82334 inhibited the responses to [Sar9]substance P sulfone but not that to [betaAla8]neurokinin A (4-10). These data provide evidence that tachykinin NK2 receptors predominantly mediate the non-adrenergic non-cholinergic excitatory transmission to the circular muscle of the corpus of guinea-pig stomach. In addition, after blocking the non-adrenergic non-cholinergic inhibitory junction potential by apamin, L-nitroarginine and tetraethylammonium, the fast component of the non-adrenergic non-cholinergic excitatory junction potential could be mediated by adenosine triphosphate.

An ultrastructural study of calcitonin gene-related peptide-immunoreactive nerve fibers innervating the rat posterior longitudinal ligament. A morphologic basis for their possible efferent actions

STUDY DESIGN

The present study investigated ultrastructural characteristics of calcitonin gene-related peptide-immunoreactive nerve fibers in the posterior longitudinal ligament of the rat lumbar spine.

OBJECTIVES

To provide a morphologic basis for assessment of the afferent and, in particular, efferent functions of calcitonin gene-related peptide immunoreactive nerves in the posterior longitudinal ligament and their eventual role in degenerative spondylarthropathies and low back pain.

SUMMARY OF BACKGROUND DATA

Previous studies using light-microscopic localization of sensory neuronal markers such as calcitonin gene-related peptide have reported the presence of sensory fibers in the supporting structures of the vertebral column. Meanwhile, accumulating research data have suggested efferent properties for calcitonin gene-related peptide, i.e., a trophic action that alters the intrinsic properties of target cells not through transient action of synaptic transmission, but through long-lasting signal transmission by the secreted neuropeptides. To verify such trophic, paracrine actions of the calcitonin gene-related peptide-containing fibers in the posterior longitudinal ligament, however, ultrastructural details of the terminals and their spatial relationship to their eventual target structures have to be elucidated.

METHODS

Rat posterior longitudinal ligaments were stained immunohistochemically for calcitonin gene-related peptide. Light-microscopic analysis of the semithin sections facilitated subsequent electron microscopy of specific sites of the posterior longitudinal ligament to determine ultrastructural details and nerve fiber-target relationships.

RESULTS

The rat lumbar posterior longitudinal ligament was found to be innervated by two distinctive calcitonin gene-related peptide immunoreactive nerve networks. In immunoelectronmicroscopy, the fibers of the deep network had numerous free nerve endings, whereas those of the superficial network showed spatial associations with other non-calcitonin gene-related peptide immunoreactive components of the network. In both systems, naked axons not covered by the Schwann cells made close spatial contact with smooth muscle cells: of blood vessels and resident posterior longitudinal ligament fibroblasts.

CONCLUSIONS

The ultrastructural characteristics of the innervation of the rat posterior longitudinal ligament would be compatible not only with a nociceptive function, but also with neuromodulatory, vasoregulatory, and trophic functions, as has already been established in some visceral organs.

Synergistic effect of substance P with epidermal growth factor on epithelial migration in rabbit cornea

In order to investigate the role of neural regulation in corneal epithelial healing, we examined the effect of substance P (SP) on corneal epithelial migration using an organ culture system of rabbit corneas. We investigated the synergistic effects of SP with (1) growth factors: epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta(TGF-beta); (2) extracellular matrix proteins: fibronectin, vitronectin, laminin, and collagen type IV; and (3) cytokines: interleukin-1alpha (IL-1alpha), IL-1beta, and interleukin-6 (IL-6). Rabbit corneal blocks were cultured in the absence or presence of various reagents for 24 hr. The corneal blocks were then fixed, dehydrated, embedded in paraffin and stained by hematoxylin-eosin, and the length of the path of epithelial migration was measured. The addition of SP alone, at concentrations up to 50 microg ml-1, did not affect epithelial migration. EGF, fibronectin, vitronectin, collagen type IV, and IL-6 stimulated epithelial migration, but bFGF, TGF-beta, laminin, IL-1alpha, and IL-1betadid not. The stimulatory effect of EGF on the epithelial migration was enhanced by the presence of SP. This synergistic effect of SP and EGF on corneal epithelial migration was abolished by the addition of an SP antagonist or enkephalinase. Other neurotransmitters (vasoactive intestinal peptide, calcitonin gene-related peptide, acetylcholine chloride, norepinephrine, serotonin) and tachykinins (neurokinin A, neurokinin B, kassinin, eledoisin, physalaemin) were examined, but none exhibited a synergistic effect with EGF. Interestingly, EGF alone stimulated the incorporation of 3H-thymidine into corneal epithelial cells, but the addition of SP with EGF did not enhance this effect. These results demonstrate that SP enhanced the EGF stimulation of corneal epithelial migration in vitro in a specific manner, suggesting a possible role of SP as a modulator of epithelial wound healing.

Substance P augments fibrogenic cytokine-induced fibroblast proliferation: possible involvement of neuropeptide in tissue fibrosis

Sodium-butyrate-pretreated and Con A-stimulated P815 mast cell line generated 3T3 fibroblast proliferating activity. This fibroblast stimulatory activity was partially abrogated by three different substance P antagonists such as spantide (NK1 antagonist), FK224 (NK1 and NK2 antagonist) or FK888 (NK1 antagonist) or anti-substance P antibody. In addition to P815 mastocytoma cell, IL3-dependent, bone marrow-derived mast cells also generated fibroblast proliferating activity which was also partially abrogated by substance P antagonists. Anti-fibrogenic cytokine antibodies also inhibited mast cell-derived fibroblast proliferating activity. Substance P or histamine augmented fibrogenic cytokine-induced fibroblast proliferation which indicates that mast cell-derived histamine or substance P play an important role in induction of tissue fibrosis in fibrosing diseases.

Dental innervation: functions and plasticity after peripheral injury

Oral tissues including the periodontal ligament, gingiva, and tooth pulp have a relatively dense sensory innervation and a rich vascular supply. Teeth and supporting tissues are susceptible to tissue injury and inflammation, partly due to lack of collateral blood and nerve supply and to their low compliance. This review focuses on dental nerve functions and adaptive changes in the trigeminal ganglion and tooth pulp after peripheral injuries. An overview of the peptidergic innervation of oral tissues is presented, followed by a discussion of plasticity in neuropeptide expression in trigeminal peripheral neurons after local insults to teeth and peripheral nerve injuries. The functional implications of these adaptive changes are considered, with special reference to nerve regeneration, inflammation, and hemodynamic regulation.

Abnormal afferent nerve endings in the soft palatal mucosa of sleep apnoics and habitual snorers

Habitual snoring precedes obstructive sleep apnea (OSA), but the pathophysiological mechanisms behind progression are still unclear. The patency of upper airways depends on a reflexogen mechanism reacting on negative intrapharyngeal pressure at inspiration, probably mediated by mucosal receptors, i.e., via afferent nerve endings. Such nerves contain a specific nerve protein, protein-gene product 9.5 (PGP 9.5) and in some cases substance P (SP) and calcitonin gene-related (CGRP). Biopsies of the soft palatial mucosa were obtained from non-smoking men ten OSA patients, 11 habitual snorers and 11 non-snoring controls. The specimens were immunohistochemically analyzed for PGP 9.5, SP and CGRP. As compared to controls, an increased number of PGP-, SP- and CGRP-immunoreactive nerves were demonstrated in the mucosa in 9/10 OSA patients and 4/11 snorers, in addition to varicose nerve endings in the papillae and epithelium. Using double staining methodology, it could be shown that SP- and CGRP-like immunoreactivities (LIs) often coexisted in these fibres, as did CGRP- and PGP 9.5-LIs. The increased density in sensory nerve terminals are interpreted to indicate an afferent nerve lesion. Our results support the hypothesis of a progressive neurogenic lesion as a contributory factor to the collapse of upper airways during sleep in OSA patients.

Efferent targets of osseous CGRP-immunoreactive nerve fiber before and after bone destruction in adjuvant arthritic rat: an ultramorphological study on their terminal-target relations

We report the ultramorphological characterization of the terminal-target relation of sensory peptidergic nerve fibers in healthy and diseased osseous tissues. Bone tissue sections were immunoelectronmicroscopically investigated for calcitonin gene-related peptide (CGRP), a neuropeptide widely distributed in sensory peptidergic fibers. Ultramorphological relation of the osseous CGRP-immunoreactive (ir) nerve terminals and their target cells was comparatively analyzed using healthy, arthritic, and postarthritic bone specimens from control and adjuvant-induced arthritic rats. Terminal-like profiles of the osseous CGRP-ir axons were evidenced in direct contact with the metaphyseal osteoblasts and osteoclasts of the control animals. Terminal-like profiles were also noted in the vicinity of the periosteal lining cells. Nonterminal-like profiles did not make intimate spatial relation to the cells/structures surrounding the nerve. Osseous CGRP-ir terminals and axons, which are either uncovered or thinly ensheathed by the supportive tissues, were extensively degenerated in adjuvant-induced infiltration, whereas larger fibers were relatively resistant. Numerous CGRP-ir axons with distinctive features reinnervated the postarthritic, ossifying periosteum. CGRP-ir axons appeared to reinnervate the eroded surface of metaphyseal bone and cartilage as early as the recruited osteoblasts resume osteogenesis in the postarthritic metaphysis. The observed terminal-target relations in the healthy and diseased bone tissues give an ultramorphological basis for the putative trophic, modulatory actions of CGRP innervation of the bone cells.

Functional expression of bombesin receptor in most adult and pediatric human glioblastoma cell lines; role in mitogenesis and in stimulating the mitogen-activated protein kinase pathway

Functional bombesin receptors were identified in most human glioblastoma cell lines examined (approximately 85% of lines). Bombesin stimulated the release of intracellular Ca2+ in human adult (U-373MG, D-247MG, U-118MG, U-251MG, D-245MG, U-105MG, D-54MG, A-172MG, and D-270MG lines) and pediatric (SJ-S6 and SJ-G2 lines) glioblastoma cell lines. Stimulation of the glioblastoma cell line U-373MG with bombesin or gastrin-releasing peptide (GRP) induced mitogenesis, measured by [3H]thymidine incorporation into DNA, and stimulated the tyrosine phosphorylation of the mitogen-activated protein (MAP) kinases (Erk1 and Erk2). The stimulation of the MAP kinase phosphorylation in U-373MG cells was time- and peptide concentration-dependent. Both bombesin and GRP showed similar potencies in stimulation of intracellular Ca2+ release and activation of the MAP kinase pathway in U-373MG cells, whereas neuromedin B (NMB) peptide was less potent. Bombesin and GRP induced the release of cytosolic Ca2+ in a concentration-dependent manner. Because bombesin and GRP were more potent than NMB peptide in increasing the cytosolic Ca2+ levels in U-373MG cells, we concluded that the BB2 subtype (also known as GRP-preferring receptor subtype) of the bombesin receptor is expressed in this cell line. The bombesin receptor antagonist ([Leu13-psi(CH2NH)Leu14]bombesin) blocked bombesin induced Ca2+ release and attenuated MAP kinase activation in U-373MG cells demonstrating that bombesin is acting through a receptor-dependent mechanism. This study indicates that functional bombesin receptors are widely expressed in human glioblastoma cell lines.

Cutaneous vascular response to calcitonin gene-related peptide in psoriasis and normal subjects

To determine whether cutaneous blood vessels in subjects with psoriasis possess a generalized inherently abnormal response to neuropeptides, the effect of three doses of intradermally injected calcitonin gene-related peptide (CGRP) on skin blood flow in normal subjects (n = 10), and on clinically normal skin (greater than 5 cm from psoriatic lesions) in subjects with psoriasis (n = 9) was measured using a laser Doppler technique. Calcitonin gene-related peptide caused a dose-dependent increase in local blood flow in both psoriatic and normal subjects, which was not statistically different between the two groups. This study has shown that the cutaneous vasculature at sites distant from lesions of psoriasis (> 5 cm) is not inherently different from normal skin in its response to CGRP.

Inhibition of proliferation and stimulation of migration of endothelial cells by secretoneurin in vitro

Vascular cell responses in inflammation are affected by several neuropeptides of perivascular nerve fibers. Secretoneurin is a 33-amino acid peptide that is coreleased from these nerve endings with other proinflammatory neuropeptides, eg, substance P and calcitonin gene-related peptide. Furthermore, secretoneurin has been shown to be chemotactic for human skin fibroblasts and human blood monocytes in vitro and in vivo. An action on cellular components of the vascular wall is not yet reported. We therefore investigated in vitro effects of this novel sensory neuropeptide on endothelial cells. Secretoneurin exerted a potent and reversible inhibitory effect both on endothelial cell growth under low serum conditions (1% fetal calf serum) and endothelial cell growth factor-activated endothelial cell proliferation. We show in the present study that secretoneurin exerts this effect on aortic (rat) and pulmonary artery (bovine) endothelial cells, as well as venous (human umbilical vein) endothelium. Endothelial cell chemotaxis was tested by means of three different migration assays employing nitrocellulose and polycarbonate micropore filters. Secretoneurin consistently exhibited potent chemoattractant activity. The effective concentrations for the observed effects were in the picomolar range. The combination of chemotactic and antiproliferative effects on endothelial cells suggests that secretoneurin may act as a regulatory factor of vascular cell functions.

Age-related changes of VIP, NPY and somatostatin-immunoreactive neurons in the cerebral cortex of aged rats

Recent studies have explored certain changes with aging of neurons containing neuropeptides. The degree of loss of vasoactive intestinal polypeptide (VIP)-, neuropeptide Y (NPY)- and somatostatin-containing neurons in the aged CNS has not yet been established with certainty however, and available data is often contradictory. Changes with aging of VIP- and NPY-containing neurons were demonstrated by immunocytochemistry in this study. A major loss of VIP-immunoreactive (ir) neurons in aged rat brain was observed in the frontal cortex area 3, parietal cortex area 1, hindlimb area, temporal cortex area 1 and 2, monocular part of occipital cortex area 1, occipital cortex area 2, and retrosplenial cortex. VIP-ir cells in the frontal cortex areas 1 and 2, parietal cortex area 2, forelimb area, binocular part of the occipital cortex area 1, and the dentate gyrus were moderately decreased. The axis of VIP neurons in the aged group showed an irregular orientation tendency, especially in layers II and III. Major loss of NPY-ir neurons in aged rat brain were observed in the retrosplenial cortex, frontal cortex areas 1 and 2, parietal cortex areas 1 and 2, occipital cortex areas 1 and 2, the temporal cortex, hippocampus proper and cingulate cortex. Loss of NPY-ir neurons was observed mostly in layers V and VI. The number and length of dendritic branches also appeared to have decreased and shortened in the aged group. There were only slight decreases of somatostatin-ir cell numbers in the parietal and occipital cortex of the aged group. These results indicate the involvement of VIP and NPY-ir neurons in the aging process of cerebral cortex, and provide the morphological evidence for the decreased number of VIP and NPY neurons by immunocytochemistry in each area of cerebral cortex of aged rats.

Wound healing--aiming for perfect skin regeneration

The healing of an adult skin wound is a complex process requiring the collaborative efforts of many different tissues and cell lineages. The behavior of each of the contributing cell types during the phases of proliferation, migration, matrix synthesis, and contraction, as well as the growth factor and matrix signals present at a wound site, are now roughly understood. Details of how these signals control wound cell activities are beginning to emerge, and studies of healing in embryos have begun to show how the normal adult repair process might be readjusted to make it less like patching up and more like regeneration.

Tyrosine hydroxylase-immunoreactive nerve fibres in rat posterior longitudinal ligament

The nerve supply to the posterior longitudinal ligament (PLL) of the lumbar vertebrae has been the focus of considerable interest to gain insight into the pathogenesis of low back pain. The present study aimed to characterize the sympathetic fibres in the PLL by immuno-electronmicroscopy for tyrosine hydroxylase (TH), the rate limiting enzyme in catecholamine synthesis. The posterior central branches of the segmental lumbar arteries received numerous communicating fibres from the sinuvertebral nerve (SVN), but only shortly after their entrance to the spinal canal. The non-vessel-associated branches of the SVN formed transverse bundles, which met fibres from the opposite side in a plexus-like mid-sagittal network. As these fibres approached the midline, they gradually lost their Schwann cell cover. The free and naked fibres contained numerous terminal-like varicosities. The TH-ir and 6-hydroxydopamine (6-OH-DA) sensitive fibres were intermingled with non-TH-ir fibres. The TH-ir sympathetic fibres had no obvious target structures except for the numerous, intermingled, closely related and communicating terminal-like axons in the mid-sagittal network in contact with non-TH-ir fibres. This may represent a neuroanatomical equivalent reflecting modulatory functions, which could participate in the pathogenesis of low back pain.

Localization of leukaemia inhibitory factor to airway epithelium and its amplification of contractile responses to tachykinins

1. In neural tissue, leukaemia inhibitory factor (LIF) is an important trophic cytokine. In this investigation, we determined if LIF was present in human and guinea-pig airways and examined the role of this cytokine in modulating airway responses to endogenous and exogenous tachykinins as well as muscarinic receptor and beta-adrenoceptor stimulation. 2. The presence of LIF in both human and guinea-pig airways was determined by immunohistochemistry. Guinea-pig tracheal explants were incubated in CRML-1066 media containing LIF (0.5, 5 or 50 ng ml-1) for periods of 3, 6, 24 and 48 h. Tracheal rings were then transferred to organ baths for measurement of isometric force in response to carbachol, capsaicin, the neurokinin1 (NK1) receptor agonist [Sar9,Met(O2)11]-substance P (SP), the NK2 receptor agonist neurokinin A (NKA) and isoprenaline. 3. LIF immunoreactivity was observed primarily in basally situated cells in the airway epithelium of both large and small airways. Less intense immunoreactivity was observed in vascular endothelium and glandular epithelium. 4. Treatment with LIF (0.5 ng ml-1) for 3 and 6 h significantly increased contractile responses to capsaicin by 42% and 43%, respectively, compared to time controls, whereas higher concentrations of LIF (5 and 50 ng ml-1) enhanced capsaicin-induced contractions only after 6 h. After 24 h, responses to capsaicin were not significantly different from 0 h control. Contractile responses to capsaicin following exposure to LIF at any concentration for 24 h were not significantly different from relative time control values. 5. Responses to [Sar9,Met(O2)11]-SP, carbachol and isoprenaline were not influenced by time in culture or by exposure to LIF for up to 48 h. Contractile responses induced by NKA were not influenced by 3 or 6 h exposure to LIF, but at 24 and 48 h the mean maximum contractile responses to NKA were significantly increased by 33% and 35%, respectively, compared to control. 6. These results demonstrate that LIF is present in guinea-pig and human airway epithelium, and modulates airway responses to tachykinins. In the acute setting LIF augments the capsaicin-induced release of endogenous tachykinins, whilst in the longer term (> 24 h), LIF increases airway smooth muscle responses to tachykinins via an NK2 receptor selective mechanism. We conclude that LIF may be an important effector molecule in the response of airways to injury or inflammation.

Ganglionic axons in motor roots and pia mater

In addition to motor axons and preganglionic axons, ventral roots contain unmyelinated or thin myelinated sensory axons and postganglionic sympathetic axons. It has been said that ventral roots channel sensory axons to the CNS. However, it now seems that these axons end blindly, shift to the pia or loop and return towards the periphery and that these units reach the CNS via dorsal roots. Sensory ventral root axons project from a variety of somatic or visceral receptors; some of them are third branches of dorsal root afferents and some seem to lack a CNS projection. Many ventral root afferents contain substance P (SP) and/or calcitonin gene-related peptide (CGRP). These fibres are not affected by neonatal capsaicin treatment and they cannot induce radicular or pial extravasation. Some thin ventral root axons are sympathetic and relate to blood vessels. Afferents containing SP and/or CGRP and sympathetic axons also occur in the spinal pia mater. The sensory axons mediate pain. They might also have vasomotor, tissue-regulatory and/or mechanoreceptive functions. The motor roots of cranial nerves IV, VI and XI contain unmyelinated axons arranged like in ventral roots outside the autonomic outflow. However, the motor root of cranial nerve V channels some unmyelinated axons into the CNS. The occurrence of thin axons in ventral roots and pia mater changes during development and ageing. After peripheral nerve injury, ipsilateral ventral roots and pia are invaded by new sensory and postganglionic sympathetic axons.

Dopamine and the regulation of cell proliferation in gerbil (Meriones unguiculatus) pyloric mucosa

The epithelium of the digestive system mucosa consists of a highly dynamic cell population. The conditions under which mitotic activity in the gastrointestinal epithelium is regulated is as yet poorly understood. Nevertheless, it is assumed that some biogenic amines might be involved. Having demonstrated that dopaminergic cells occur in the stomach of gerbils (Meriones unguiculatus), in the present study we examined the influence of dopamine antagonist haloperidol on the proliferation of epithelial cells in the mucosa of the stomach. Proliferating cells were detected immunocytochemically and quantified after in-vivo labeling with 5-bromo-2'-desoxyuridine in both haloperidol- and saline-treated animals. The results show that acute doses of haloperidol significantly increases the proliferation rate in the pyloric mucosa, suggesting that dopamine plays a probable modulatory role in the regulation of mitotic activity. These findings are discussed with regard to the role of paraneurons in regulating epithelial mitosis.

Magnesium deficiency-related changes in lipid peroxidation and collagen metabolism in vivo in rat heart

Magnesium deficiency is known to produce a cardiomyopathy, characterised by myocardial necrosis and fibrosis. As part of the ongoing investigations in this laboratory to establish the biochemical correlates of these histological changes, the present study probed the extent of lipid peroxidation and alterations in collagen metabolism in the heart in rats fed a magnesium-deficient diet for 28, 60 or 80 days. While lipid peroxidation was measured by the thiobarbituric acid reaction, collagen turnover rates and fibroblast proliferation were assessed using [3H]-proline and [3H]-thymidine, respectively. Tissue levels of magnesium and calcium were determined by atomic absorption spectrophotometry. A 39% increase in the cardiac tissue level of thiobarbituric acid reactive substances was observed on day 60 of deficiency (p < 0.001). A marked drop in collagen deposition rate (59%, p < 0.001%) on day 28 but a significant rise in fractional synthesis rate (12%, p < 0.001) and collagen deposition rate (24%, p < 0.001) on day 60 were observed. A fibroproliferative response in the heart was evident on day 80 but not at earlier time-points. Thus, the present study provides evidence of increased lipid peroxidation and net deposition of collagen in the myocardium in response to dietary deficiency of magnesium. These changes were, however, not directly related to alterations in the tissue levels of Mg. It is suggested that the increase in cardiac collagen synthesis and fibroplasia associated with Mg deficiency may represent reparative fibrogenesis, upon oxidative damage to the cardiac muscle, and is mediated by a mechanism independent of changes in cardiac tissue levels of Mg.

Cellular and molecular mechanisms of pulmonary vascular remodeling

In many organs and tissues, the cellular response to injury is associated with a reiteration of specific developmental processes. Studies have shown that, in response to injury, vascular wall cells in adult organisms express genes or gene products characteristic of earlier developmental states. Other genes, expressed preferentially in adult cells in vivo, are down-regulated following injurious stimuli. Complicating matters, however, are recent observations demonstrating that the vascular wall is comprised of phenotypically heterogeneous subpopulations of endothelial cells, smooth muscle cells, and fibroblasts. It is unclear how specific subsets of cells respond to injury and thus contribute to the vascular remodeling that characterizes chronic pulmonary hypertension. This review discusses vascular development in the lung and the cellular responses occurring in pulmonary hypertension; special attention is given to heterogeneity of responses within cell populations and reiteration of developmental processes.

Analysis of cutaneous sensory neurons in transgenic mice lacking the low affinity neurotrophin receptor p75

Mice with a targeted mutation of the p75 low affinity neurotrophin receptor display smaller peripheral nerves and dorsal root ganglia. Here we show that transgenic mice have a significant elevation of thresholds to noxious mechanical and heat stimuli compared with p75+/+ control mice. Immunocytochemical analysis using antibodies against PGP 9.5 (a panaxonal marker) and calcitonin gene related peptide (CGRP, which labels peptidergic neurons) showed a reduction to 73% and 54%, respectively, of the epidermal innervation density. However, analysis of the cell size distribution of toluidine blue-stained dorsal root ganglia showed no selective loss of neurons of particular diameters. Moreover, the neurochemical profile of dorsal root ganglia cells as defined by trkA, CGRP, IB4 and RT97 immunostaining revealed no significant differences in comparison with p75+/+ animals. Staining of the dorsal horn of the spinal cord for CGRP and IB4 was also normal in p75-/- animals. Taking into account a previously reported loss of approximately 50% dorsal root ganglion neurons, we conclude that all types of sensory neurons are equally depleted in p75-/- mice and that the absence of p75 impedes the development of more than one neuronal subtype.

[Edema caused by retroperitoneal and tricuspid fibrosis with sclerodermatous cutaneous involvement disclosing carcinoid tumor. Apropos of a case and review of the literature]

A 65-year-old female was admitted with leg edema by retroperitoneal fibrosis and tricuspid valve incompetence by fibrosis, cutaneous fibrosis, moderate flushing over the upper body without diarrhea. It revealed an ileal carcinoid tumor with hepatic metastases. Octreotide (Sandostatine), tumor excision and interferon alpha 2b treatment led to a regression of flushing and edema, a reduction of fibrosis and a stabilization of the metastatic carcinoid, with normal serotonin levels.

Calcitonin gene-related peptide, substance P, and tyrosine hydroxylase-immunoreactive innervation of rat bone marrows: an immunohistochemical and ultrastructural investigation on possible efferent and afferent mechanisms

The presence of nerve fibers in bone marrow has been noted by various investigators, and recent developments in immunohistochemistry have enabled differential localization of the intramedullary nerve fibers. Much interest has been devoted to the efferent activities of the afferent fibers, which probably act on the target tissues by secreting a variety of neurotransmitters. The present study aimed to further characterize intramedullary substance P, calcitonin gene-related peptide, and tyrosine hydroxylase-immunoreactive nerve fibers of the rat lower limb by comparing those of the knee, ankle, and tarsal joints. The ultrastructural details of intramedullary calcitonin gene-related peptide-immunoreactive axons were also investigated to provide a morphological basis for their possible efferent actions. Intramedullary calcitonin gene-related peptide and substance P-immunoreactive fibers in the proximal tibia and the knee joint were found to be as reported earlier, but the marrow of the distal metaphysis was also noted to be richly innervated, and the tarsal joints displayed dense innervation at the subchondral regions that underlie the joint cartilage. The articular and intramedullary innervations that function for joint protection might participate in characteristic clinical features of joint damage secondary to the neuropathies. Ultrastructurally, the intramedullary calcitonin gene-related peptide-immunoreactive axons were minimally engulfed by the Schwann cell, and naked intramedullary calcitonin gene-related peptide-immunoreactive axons were noted along an extraordinarily long extension, suggesting much efferent activity.

Immunocytochemical characterization of malignant schwannoma-derived cells in culture

We recently demonstrated that cultured malignant schwannoma (MS)-derived cells can support human skin mast cell (HSMC) survival in vitro. Cultured HSMCs were spindleshaped in close contract with MS-derived cells, suggesting cell to cell interaction. To elucidate the mechanism of the enhanced HSMC survival in coculture with MS-derived cells and the cellular interactions between HSMC and MS-derived cells, we examined the immunocytochemical characteristics of MS-derived cells using immunofluorescence. Morphologically, cultured MS-derived cells were polygonal with abundant cytoplasm and resembled perineurial cells. The cultured cells immunoreacted positively with vimentin, fibronectin, laminin and collagen IV, but negatively with anti-S100 protein, anti-neuron specific enolase, and anti-neurofilament (68 kd, 145 kd, 200 kd) antibodies. MS-derived cells were distinct from Schwann cells in their lack of S100 protein and also distinguishable from endoneurial fibroblasts that produce fibronectin, but never expressed laminin or collagen IV. MS-derived cells thus possess the characteristics of perineurial cells in their general morphology and their immunocytochemical properties. Immunoreactivity for substance P (SP) and neurokinin A (NKA) was found in the cytoplasm of these cells, particularly around the nuclei. Vasoactive intestinal peptide, somatostatin, and calcitonin gene related peptide were negative. From these findings, we characterized the MS-derived cell's in vitro properties and concluded that it is similar to a perineurial cell. The extracellular matrix protein, laminin, and fibronectin expressed in the MS-derived cell might contribute to HSMC survival and morphology through cell to matrix adhesion. Neuropeptides such as SP and NKA, expressed in the MS-derived cell, might play some role in enhanced HSMC survival in vitro.

Age-related changes in calcitonin gene-related peptide and substance P in renal afferent nerve soma in the rat. Association with afferent renal nerve activity

Renal afferent neurons were retrogradely labeled with FluoroGold in Sprague-Dawley rats at 50, 60, 70, 80, 90, 110, 130 and 200 days of age. Recordings of afferent renal nerve activity (ARNA) and immunofluorescent assessment of calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) and substance P (SP)-LI in spinal ganglia T10-L1 were obtained in the same rats. The frequency of renal afferent neurons positive for CGRP-LI declined abruptly from 88% in animals younger than 100 days of age (342 of 388 total cells) to 63% in rats older than 100 days of age (223 of the 353 total cells). The intensity of CGRP-LI (scaled 1-3) in renal afferent CGRP-positive neurons also declined significantly from a mean of 2.23 +/- 0.04 before 100 days to 1.48 +/- 0.05 in older rats (P < 0.001 in each age group). SP-LI positive neurons declined from 44% to 28% (P < 0.001). These changes in neuropeptide immunofluorescence coincided with an altered pattern of ARNA in which the excitatory response to complete renal ischemia increased from 274 +/- 69% above background to 1167 +/- 124% after the age of 100 days. Previous studies have shown that this alteration in the ARNA response to renal ischemia is due to the appearance of activity from R1 chemoreceptor nerves in ARNA. These data demonstrated that this transition in the electrophysiologic characteristics of ARNA is accompanied by profound alterations in CGRP-LI and SP-LI levels in renal afferent nerve cell bodies.

Effect of capsaicin treatment or inferior alveolar nerve resection on dentine formation and calcitonin gene-related peptide- and substance P-immunoreactive nerve fibres in rat molar pulp

The aim of this study was to investigate whether decreased sensory innervation induced by capsaicin treatment or axotomy of the inferior alveolar nerve has an effect upon dentine formation in the rat first molar. Dentine formation was visualized by intravital injection of Procion brilliant Red H8BS and denervation was verified immunohistochemically for the neuropeptides calcitonin gene-related peptide (CGRP) and substance P. The observation times were 6 weeks for the capsaicin-treated group and 11 days for the axotomized group. Capsaicin injections caused a consistent reduction in numbers of CGRP- and substance P-immunoreactive fibres in the pulps and a somewhat smaller reduction in the periodontal tissues. Unilateral axotomy of the inferior alveolar nerve induced an almost complete loss of immunoreactive fibres in the pulp and in the mesial gingiva of the first molar. Dentine formation at the mesial pulp horn and at the central pulp floor was significantly reduced in both groups compared to controls. The results suggest that sensory neuropeptides such as CGRP and substance P may play a part in dentine formation.

Innervation of melanocytes in human skin

Communication between the nervous system and epidermal melanocytes has been suspected on the basis of their common embryologic origin and apparent parallel involvement in several disease processes, but never proven. In this study, confocal microscopic analysis of human skin sections stained with antibodies specific for melanocytes and nerve fibers showed intraepidermal nerve endings in contact with melanocytes. This intimate contact was confirmed by electron microscopy, which further demonstrated thickening of apposing plasma membranes between melanocytes and nerve fibers, similar to synaptic contacts seen in nervous tissue. Since many intraepidermal nerve fibers are afferent nerves that act in a "neurosecretory" fashion through their terminals, cultured human melanocytes were stimulated with calcitonin gene-related peptide (CGRP), substance P, or vasoactive intestinal peptide, neuropeptides known to be present in cutaneous nerves, to examine their possible functions in the epidermal melanin unit. CGRP increased DNA synthesis rate of melanocytes in a concentration- and time-dependent manner. Cell yields after 5 d were increased 25% compared with controls maintained in an otherwise optimized medium. Furthermore, stimulation by CGRP induced rapid and dose-dependent accumulation of intracellular cAMP, suggesting that the mitogenic effect is mediated by the cAMP pathway. These studies confirm and expand a single earlier report in an animal model of physical contact between melanocytes and cutaneous nerves and for the first time strongly suggest that the nervous system may exert a tonic effect on melanocytes in normal or diseased human skin.

[Projections and fiber characteristics of sensory afferents of the anterior cruciate ligament in an animal experiment]

The sensory innervation of the rabbit anterior cruciate ligament was studied by retrograde tracing technique using wheat-germ-agglutinin-horseradish-peroxidase (WGA-HRP) and Fast Blue as neuronal tracers. Injection of the tracer into the ligament was followed by histo- and immunohistochemical investigation of labelled nerve cell bodies located in the dorsal root ganglia. In 4 animals we injected the tracer into the joint cavity to label general joint afferents. The segmental distribution of retrogradely labelled neurons following injection into the anterior cruciate ligament (L6, L7, S1) is significantly different from the distribution pattern after injection into the knee joint (L4-S2). Retrogradely labelled nerve cells innervating the anterior cruciate ligament were further investigated using immunohistochemical and morphometric analysis. The sensory innervation of the anterior cruciate ligament is therefore comprised of at least 2 different qualities of sensory afferent nerves: 1. Small neurones immunoreactive to the inflammatory peptide substance P most likely transmitting nociceptive information centrally (44%). 2. Large, presumably fast conducting A-fibre-afferents characterized by neurofilament proteins transmitting proprioceptive information from corpuscular mechanoreceptors (43%). The results of this study put further weight to the importance of the sensory role of the anterior cruciate ligament using neuroanatomical and immunohistochemical techniques.

Synergistic effects of substance P with insulin-like growth factor-1 on epithelial migration of the cornea

We find that substance P (SP) and insulin-like growth factor-1 (IGF-1) demonstrate a synergistic effect on the stimulation of rabbit corneal epithelial migration in an organ culture. The addition of either SP or IGF-1 alone did not affect epithelial migration, while the combination of SP and IGF-1 stimulated epithelial migration in a dose-dependent fashion. The synergistic effects of SP and IGF-1 on corneal epithelial migration were nulled by the addition of a SP antagonist or enkephalinase. Among neurotransmitters (vasoactive intestinal peptide, calcitonin gene-related peptide, acethylcholine chloride, norepinephrine, serotonin) or tachykinins (neurokinin A, neurokinin B, kassinin, eledoisin, physalaemin), only SP demonstrated a synergistic effect with IGF-1 on cellular migration. In contrast, the combination of SP and IGF-1 did not affect the incorporation of 3H-thymidine into corneal epithelial cells. The attachment of the corneal epithelial cells to fibronectin, collagen type IV, and laminin matrices increased after treatment of the cells with SP and IGF-1, but SP or IGF-1 by themselves did not affect the attachment of the cells to these extracellular matrix proteins. An identical synergistic effect on corneal epithelial migration was observed when an NK-1 receptor agonist was used in place of SP, suggesting the synergistic effect of SP and IGF-1 might be mediated through the NK-1 receptor system. These results suggest that the maintenance of the normal integrity of the corneal epithelium might be regulated by both humoral and neural factors.

Coiled mechanoreceptors in Aplysia revealed by sensorin immunofluorescence and confocal microscopy

Identified mechanosensory neurons of Aplysia are established model neurons for studies on learning and memory, and for examining responses to axonal injury. Although many characteristics of these sensory neurons have received intensive study, the nature of the peripheral mechanoreceptive endings remains unknown. Identification of a peptide, sensorin, specific in Aplysia for mechanosensory neurons, led to the development of an antibody which proved useful in studying the peripheral morphology of these neurons. Immunostaining for sensorin in tail body wall revealed that sensorin is present in peripheral arborizations. Examination of sensorin-positive fibers in the periphery revealed that they terminate as coiled structures in the muscle layer of the body wall. These coiled structures (approximately 0.5 microns diameter processes, 2-3 microns across the coil, approximately 60 microns long) run parallel to muscle fibers and have a pitch of about one turn per 4 microns. Sensorin immunostaining was particularly intense in varicosities, both along peripheral fibers and along the coiled structure. The localization of sensorin suggests that it may be released peripherally where it could have various paracrine and/or autocrine neuromodulatory actions.

Tachykinins, neurotrophism and neurodegenerative diseases: a critical review on the possible role of tachykinins in the aetiology of CNS diseases

The tachykinins are a family of undecapeptides that are widely distributed throughout the body, including the central nervous system (CNS). They have several well defined roles in non-CNS sites as well as in the dorsal horn, where they are involved in the transmission of nociceptive information. However their function(s) in other CNS sites is unclear, but there is some evidence that they function as neuromodulators rather than neurotransmitters. This neuromodulation includes a possible role in maintaining the integrity of neuronal populations, analogous to the functions of neurotrophic factors. This review critically evaluates the role of tachykinins as neurotrophic factors, with particular reference to the common neurodegenerative diseases of the CNS.

Neuropeptides, nerve growth factor and eczema

Considerable evidence indicates that peripheral nerve fibres play an active regulatory role during eczematous reactions. Many basic features of the inflammatory process are potentially subject to neuropeptidergic modulation, such as vascular changes, cellular trafficking activation and trophism in vivo and in vitro investigations suggest that neuropeptides are part of the complex network of mediators that initiate and maintain the eczematous process in the skin. In general, peptidergic fibres seem to exert a global protective role, but with specific and selective effects in the different phases. Evidence that the inflammatory process induces bio-chemical changes at a neuronal level has also been obtained. The possible mediators of the neuronal recruitment in the course of the eczematous reaction are still unknown. Nevertheless, nerve growth factor, which is locally increased during inflammatory processes and may induce peptidergic alterations, should be considered as a potential candidate molecule.

Immunohistochemical, electrophysiological, and electron microscopical study of rat fungiform taste buds after regeneration of chorda tympani through the non-gustatory lingual nerve

The sensory innervation of fungiform papillae on the rat dorsal tongue is derived from branches of two cranial nerves: the lingual branch of the trigeminal nerve which provides somatosensory innervation and the chorda tympani (CT) branch of the facial nerve, which provides innervation to the taste buds. Removal of the CT results in degeneration of the taste buds. Removal of both nerves results in reduction in size of fungiform papillae and an altered pattern of keratinization in its epithelium. Regeneration of nerves to the epithelium restores the pre-operative condition. Thus, in addition to their sensory functions, both the CT and lingual seem to exert trophic effects on the phenotypic expression of epithelial cells in the fungiform papillae. We severed both the CT and lingual nerves in rats and sutured the proximal stump of the CT to the distal stump of the lingual to promote regeneration of the CT along the lingual nerve pathway. At the same time, we prevented the proximal stump of the lingual from regenerating into the tongue. Our purpose was to determine whether and how the innervation pattern of the regenerated taste bud might be different from normal under these experimental conditions. We found that reinnervation by the CT through the lingual nerve occurs, that this restores the anatomical and functional integrity of the fungiform taste buds and papillae, and that some papillae, but not all, were richly innervated with subgemmal, extragemmal, and perigemmal neuron-specific enolase, calcitonin gene-related peptide, substance P, and neurokinin A-positive fibers. Moreover, responses to taste stimuli were recorded electrophysiologically from the CT.

The tachykinin NK1 receptor mediates the migration-promoting effect of substance P on human skin fibroblasts in culture

Fibroblast migration is an important component of the tissue response during the repair process, and substance P (SP) has been shown to exert trophic effects. In the present study, cell migration was evaluated as the distance travelled by adherent human skin fibroblasts (HF) at 96 h and by the number of individual cells moving across a filter within 5 h. In control conditions (1% calf serum) adherent fibroblasts moved from the starting line by approximately 700 microns. The addition of SP (10(-11)-10(-7) M) increased HF mobilisation in a concentration-dependent manner, with maximal activity at 10(-8) M (50% increase in migration over control). Migration of individual HF in suspension was also promoted by SP in a concentration-dependent manner, with an EC50 of 2.2 x 10(-9) M. The response produced by the maximally effective concentration of SP was equal to 65 and 90% of the effect elicited by 100 ng/ml Platelet-Derived Growth Factor A/B (PDGF A/B) on adherent and individual cells respectively. The synthetic NK1 receptor agonist [Sar9]SP-sulphone (10(-11)-10(-6) M) reproduced the SP effect. The NK2 and NK3 receptor agonists [beta Ala8]NKA(4-10) and [MePhe7]NKB were devoid of any effect. The effect of SP was antagonised by two selective antagonists of NK1 receptors, namely (+/-) CP 96,345 (10(-10)-10(-8) M) and FK 888 (10(-9)-10(-7) M), while the NK2 receptor antagonist MEN 10627 (10(-8)-10(-7) M) was not effective. Our data indicate that SP is a potent effector of fibroblast migration and the NK1 receptor is responsible for this effect. These observations further support the specific role of the NK1 receptor in mediating the trophic function of SP at the cutaneous level.