Density Of Calcitonin Gene-related Peptide Research Articles

Long-term effects of gestational diabetes mellitus on the pancreas of female mouse offspring

BACKGROUND Prolonged fetal exposure to hyperglycemia may increase the risk of developing abnormal glucose metabolism and type-2 diabetes during childhood, adolescence, and adulthood; however, the mechanisms by which gestational diabetes mellitus (GDM) predisposes offspring to metabolic disorders remain unknown. AIM To quantify the nerve axons, macrophages, and vasculature in the pancreas from adult offspring born from mouse dams with GDM. METHODS GDM was induced by i.p. administration of streptozotocin (STZ) in ICR mouse dams. At 12 wk old, fasting blood glucose levels were determined in offspring. At 15 wk old, female offspring born from dams with and without GDM were sacrificed and pancreata were processed for immunohistochemistry. We quantified the density of sensory [calcitonin gene-related peptide (CGRP)] and tyrosine hydroxylase (TH) axons, blood vessels (endomucin), and macro-phages (CD68) in the splenic pancreas using confocal microscopy. RESULTS Offspring mice born from STZ-treated dams had similar body weight and blood glucose values compared to offspring born from vehicle-treated dams. However, the density of CGRP+ and TH+ axons, endomucin+ blood vessels, and CD68+ macrophages in the exocrine pancreas was significantly greater in offspring from mothers with GDM vs control offspring. Likewise, the microvasculature in the islets was significantly greater, but not the number of macrophages within the islets of offspring born from dams with GDM compared to control mice. CONCLUSION GDM induces neuronal, vascular, and inflammatory changes in the pancreas of adult progeny, which may partially explain the higher propensity for offspring of mothers with GDM to develop metabolic diseases.

Sensory nerves, but not sympathetic nerves, promote reparative dentine formation after dentine injury via CGRP-mediated angiogenesis: An in vivo study.

Dental pulp is richly innervated by nerve fibres, which are mainly involved in the sensation of pain. Aside from pain sensation, little is known regarding the role of dental innervation in reparative dentine formation. We herein generated a mouse model of experimental dentine injury to examine nerve sprouting within the odontoblast and subodontoblastic layers and investigated the potential effects of this innervation in reparative dentinogenesis. Mouse tooth cavity model (bur preparation + etching) was established, and then nerve sprouting, angiogenesis and reparative dentinogenesis were determined by histological and immunofluorescent staining at 1, 3, 7, 14 and 28 days postoperatively. We also established the mouse-denervated molar models to determine the role of sensory and sympathetic nerves in reparative dentinogenesis, respectively. Finally, we applied calcitonin gene-related peptide (CGRP) receptor antagonist to analyse the changes in angiogenesis and reparative dentinogenesis. Sequential histological results from dentine-exposed teeth revealed a significant increase in innervation directly beneath the injured area on the first day after dentine exposure, followed by vascularisation and reparative dentine production at 3 and 7 days, respectively. Intriguingly, abundant type H vessels (CD31+ Endomucin+ ) were present in the innervated area, and their formation precedes the onset of reparative dentine formation. Additionally, we found that sensory denervation led to blunted angiogenesis and impaired dentinogenesis, while sympathetic denervation did not affect dentinogenesis. Moreover, a marked increase in the density of CGRP+ nerve fibres was seen on day 3, which was reduced but remained elevated over the baseline level on day 14, whereas the density of substance P-positive nerve fibres did not change significantly. CGRP receptor antagonist-treated mice showed similar results as those with sensory denervation, including impairments in type H angiogenesis, which confirms the importance of CGRP in the formation of type H vessels. Dental pulp sensory nerves act as an essential upstream mediator to promote angiogenesis, including the formation of type H vessels, and reparative dentinogenesis. CGRP signalling governs the nerve-vessel-reparative dentine network, which is mostly produced by newly dense sensory nerve fibres within the dental pulp.

Nerve and Vascular Biomarkers in Skin Biopsies Differentiate Painful From Painless Peripheral Neuropathy in Type 2 Diabetes.

Painful diabetic peripheral neuropathy can be intractable with a major impact, yet the underlying pain mechanisms remain uncertain. A range of neuronal and vascular biomarkers was investigated in painful diabetic peripheral neuropathy (painful-DPN) and painless-DPN and used to differentiate painful-DPN from painless-DPN. Skin biopsies were collected from 61 patients with type 2 diabetes (T2D), and 19 healthy volunteers (HV). All subjects underwent detailed clinical and neurophysiological assessments. Based on the neuropathy composite score of the lower limbs [NIS(LL)] plus seven tests, the T2D subjects were subsequently divided into three groups: painful-DPN (n = 23), painless-DPN (n = 19), and No-DPN (n = 19). All subjects underwent punch skin biopsy, and immunohistochemistry used to quantify total intraepidermal nerve fibers (IENF) with protein gene product 9.5 (PGP9.5), regenerating nerve fibers with growth-associated protein 43 (GAP43), peptidergic nerve fibers with calcitonin gene-related peptide (CGRP), and blood vessels with von Willebrand Factor (vWF). The results showed that IENF density was severely decreased (p < 0.001) in both DPN groups, with no differences for PGP9.5, GAP43, CGRP, or GAP43/PGP9.5 ratios. There was a significant increase in blood vessel (vWF) density in painless-DPN and No-DPN groups compared to the HV group, but this was markedly greater in the painful-DPN group, and significantly higher than in the painless-DPN group (p < 0.0001). The ratio of sub-epidermal nerve fiber (SENF) density of CGRP:vWF showed a significant decrease in painful-DPN vs. painless-DPN (p = 0.014). In patients with T2D with advanced DPN, increased dermal vasculature and its ratio to nociceptors may differentiate painful-DPN from painless-DPN. We hypothesized that hypoxia-induced increase of blood vessels, which secrete algogenic substances including nerve growth factor (NGF), may expose their associated nociceptor fibers to a relative excess of algogens, thus leading to painful-DPN.

The effect of orofacial complete Freund\u2019s adjuvant treatment on the expression of migraine-related molecules

BackgroundMigraine is a neurovascular primary headache disorder, which causes significant socioeconomic problems worldwide. The pathomechanism of disease is enigmatic, but activation of the trigeminovascular system (TS) appears to be essential during the attack. Migraine research of recent years has focused on neuropeptides, such as calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide 1–38 (PACAP1–38) as potential pathogenic factors and possible therapeutic offensives. The goal of present study was to investigate the simultaneous expression of CGRP and precursor of PACAP1–38 (preproPACAP) in the central region of the TS in a time-dependent manner following TS activation in rats.MethodsThe right whisker pad of rats was injected with 50 μl Complete Freund’s Adjuvant (CFA) or saline. A mechanical allodynia test was performed with von Frey filaments before and after treatment. Transcardial perfusion of the animals was initiated 24, 48, 72 and 120 h after injection, followed by the dissection of the nucleus trigeminus caudalis (TNC). After preparation, the samples were stored at − 80 °C until further use. The relative optical density of CGRP and preproPACAP was analyzed by Western blot. One-way ANOVA and Kruskal-Wallis followed by Tukey post hoc test were used to evaluate the data. Regression analysis was applied to explore the correlation between neuropeptides expression and hyperalgesia.ResultsOrofacial CFA injection resulted in significant CGRP and preproPACAP release in the TNC 24, 48, 72 and 120 h after the treatment. The level of neuropeptides reached its maximum at 72 h after CFA injection, corresponding to the peak of facial allodynia. Negative, linear correlation was detected between the expression level of neuropeptides and value of mechanonociceptive threshold.ConclusionThis is the first study which suggests that the expression of CGRP and preproPACAP simultaneously increases in the central region of activated TS and it influences the formation of mechanical hyperalgesia. Our results contribute to a better understanding of migraine pathogenesis and thereby to the development of more effective therapeutic approaches.

Streptozocin-induced type-1 diabetes mellitus results in decreased density of CGRP sensory and TH sympathetic nerve fibers that are positively correlated with bone loss at the mouse femoral neck.

Type-1 diabetes mellitus (T1DM) results in loss of innervation in some tissues including epidermis and retina; however, the effect on bone innervation is unknown. Likewise, T1DM results in pathological bone loss and increased risk of fracture. Thus, we quantified the density of calcitonin gene-related peptide (CGRP+) sensory and tyrosine hydroxylase (TH+) sympathetic nerve fibers and determined the association between the innervation density and microarchitecture of trabecular bone at the mouse femoral neck. Ten weeks-old female mice received 5 daily administrations of streptozocin (i.p. 50mg/kg) or citrate (control group). Twenty weeks later, femurs were analyzed by microCT and processed for immunohistochemistry. Confocal microscopy analysis revealed that mice with T1DM had a significant loss of both CGRP+ and TH+ nerve fibers in the bone marrow at the femoral neck. Likewise, microCT analysis revealed a significant decrease in the trabecular bone mineral density (tBMD), bone volume/total volume ratio (BV/TB), trabecular thickness (Tb.Th), trabecular number (Tb.N) and trabecular separation (Tb.Sp) in mice with T1DM as compared to control mice. Analysis of correlation revealed a positive and significant association between density of CGRP+ or TH+ nerve fibers with tBMD, BV/TV, Tb.Th and Tb.Sp, but not with trabecular number (there was a positive association only for CGRP+) and degree of anisotropy (DA). This study suggests an interaction between sensory and sympathetic nervous system and T1DM-induced bone loss. Identification of the factors involved in the loss of CGRP+ sensory and TH+ sympathetic fibers and how they regulate bone loss may result in new avenues to treat T1DM-related osteoporosis.

Abstract 314: Sensory Innervation of the Papillary Muscle: A Neural Link Between Mitral Valve Prolapse and Malignant Ventricular Arrhythmias?

Background: Malignant mitral valve prolapse (MVP) identifies a subset of patients with MVP associated with ventricular arrhythmias (VAs), including sudden cardiac death (SCD). We hypothesized that papillary muscles, which see significant mechanical stress in MVP, are richly innervated with sensory nerves, which induce severe autonomic imbalance on the heart and may trigger malignant VAs. Methods and Results: Longitudinal sections of the anterior and posterior left ventricular papillary muscles, right ventricular outflow tract (RVOT), ventricular septum, and basolateral left ventricular wall (LV) of Yorkshire pigs (n=8) were excised, formalin-fixed, paraffin-embedded, and sectioned. Immuno-staining for protein gene product 9.5 (PGP9.5), a pan-neuronal marker, and calcitonin-gene related peptide (CGRP), a sensory afferent neuron marker, was performed. Areas of immunoreactivity (IR) for CGRP were verified by direct comparison to PGP9.5 IR. The density of CGRP was then compared across anatomical regions. The mean CGRP IR area was 1229.44 ± 116.65 μm 2 /nucleus in papillary muscles, while in the septum, basolateral LV, and RVOT, the CGRP stained areas were 699.36 ± 88.28 μm 2 /nucleus, 681.51 ± 81.90 μm 2 /nucleus, and 381.98 ± 31.14 μm 2 /nucleus, respectively (p&lt;0.001). There was no significant difference between CGRP IR area in the anterior papillary muscle (1091.36 ± 189.82 μm 2 /nucleus) and the posterior papillary muscle (1347.79 ± 140.50 μm 2 /nucleus) (p&gt;0.3). Conclusions: There is a significantly greater amount of afferent innervation in the papillary muscle compared to the septum, basolateral LV, and RVOT. This enrichment of afferent innervation warrants further study to understand how afferent neurotransmission during abnormal mitral valve function may impact ventricular electrophysiology.

Spatiotemporal Changes of Calcitonin Gene-Related Peptide Innervation in Spinal Fusion.

Few studies have investigated the role calcitonin gene-related peptide (CGRP) plays in the process of spinal fusion. The aim of the present study is to observe the temporal and spatial changes of CGRP induced by experimental fusion surgery in rats and elucidate the role of CGRP in spinal fusion. Male Sprague-Dawley rats were used in the study and the specimens were collected on the 7th, 14th, 21st, and 28th day, respectively. Then, histological and immunohistochemical analysis were applied to evaluate the fusion mass and spatiotemporal changes of CGRP chronologically. The results demonstrated that density of CGRP reached peak on the 21st day after surgery and most of the CGRP expression located surrounding the interface of allograft and fibrous tissue where the cells differentiate into osteoblasts, indicating that CGRP might be involved in the process of bone formation and absorption.

Changes in peptidergic fiber density in the synovium of mice with collagenase-induced acute arthritis.

The effect of acute osteoarthritis (OA) on peripheral nerve fibers (NFs) in synovial tissue, and their association with histological changes were investigated in collagenase-induced OA mice. Collagenase (10 U in 5 μL saline) was injected into the right knee, and the same volume of saline was injected into the left knee as the control. Mice were sacrificed 1, 2, 3, and 4 weeks after the collagenase injection. Histopathological changes in the knee joints were evaluated. The numbers of protein gene product (PGP) 9.5-, calcitonin-gene-related peptide (CGRP)-, and substance P (SP)-positive NFs in the synovial tissue were determined, and their densities in the tissue were calculated. The densities of PGP 9.5- and CGRP-positive NFs in the synovium were drastically decreased 1 week after the collagenase injection. However, by week 4, the density of PGP 9.5- and CGRP-positive NFs had recovered to 84% and 79% of their normal levels, respectively. Despite the poor correlation between the synovitis score and the density of CGRP- or SP-positive NFs in the synovium, the ossification rate of chondrophytes in chondro/osteophyte lesions correlated strongly with the density of CGRP-positive NFs (R = 0.855). These results suggest that the ossification of chondrophytes occurred in parallel with the increase in CGRP-positive fiber density in the synovium during the acute phase of collagenase-induced OA.

ChemInform Abstract: Role of Angiontensin Receptors on Remodeling Perivascular Nerves

AbstractReview: 13 refs.

Role of Angiontensin Receptors on Remodeling Perivascular Nerves

The aim of this study was to investigate age-related changes in the density of calcitonin gene-related peptide (CGRP)-containing nerve fibers in spontaneously hypertensive rats (SHR) and the effects of long-term inhibition of the renin-angiotensin system on these changes. An age-related decrease in the density of CGRP-like immunoreactive (LI)-containing nerve fibers but not neuropeptide Y (NPY)-LI-containing sympathetic nerve fibers was found in the mesenteric artery of SHR but not Wistar-Kyoto rats (WKY). The density of NPY-LI-containing nerve fibers was significantly greater in SHR than in WKY. SHR were treated for 7 weeks with angiotensin-converting enzyme inhibitor (0.005% temocapril), angiotensin II type-1 (AT1) receptor antagonist (0.025% losartan), or vasodilator (0.01% hydralazine) in their drinking water. Each drug treatment significantly lowered the systolic blood pressure measured using the tail-cuff method. Long-term treatment of SHR with temocapril and losartan significantly increased the density of CGRP-LI-containing nerve fibers in mesenteric arteries. Furthermore, to clarify the effect of the angiontensin II type-2 (AT2) receptor in the restoration of perivascular nerve innervation, we used the phenol-injured rat model, in which the perivascular nerves are markedly reduced by the topical application of phenol. Activation of AT2R significantly restored CGRP-LI innervation in phenol-injured rats. These results suggest that selective stimulation of AT2 receptors facilitates reinnervation of mesenteric perivascular CGRP-containing nerves.

The effect of aging on the density of the sensory nerve fiber innervation of bone and acute skeletal pain

As humans age there is a decline in most sensory systems including vision, hearing, taste, smell, and tactile acuity. In contrast, the frequency and severity of musculoskeletal pain generally increases with age. To determine whether the density of sensory nerve fibers that transduce skeletal pain changes with age, calcitonin gene related peptide (CGRP) and neurofilament 200 kDa (NF200) sensory nerve fibers that innervate the femur were examined in the femurs of young (4-month-old), middle-aged (13-month-old) and old (36-month-old) male F344/BNF1 rats. Whereas the bone quality showed a significant age-related decline, the density of CGRP+ and NF200+ nerve fibers that innervate the bone remained remarkably unchanged as did the severity of acute skeletal fracture pain. Thus, while bone mass, quality, and strength undergo a significant decline with age, the density of sensory nerve fibers that transduce noxious stimuli remain largely intact. These data may in part explain why musculoskeletal pain increases with age.

Ameliorative effect of Eucommia ulmoides Oliv. leaves extract (ELE) on insulin resistance and abnormal perivascular innervation in fructose-drinking rats

Aim of the study Eucommia ulmoides Oliv. leaf is a traditional Chinese medicine that exhibits an anti-diabetic action. This study was designed to investigate whether long-term administration of Eucommia ulmoides Oliv. leaves extract (ELE) ameliorates pre-diabetic state of insulin resistance and abnormal perivascular innervation in the hyperinsulinemic state. Materials and methods ELE at doses of 500 and 1000 mg/kg was administered orally once daily for 4 weeks in fructose-drinking rats (FDRs). Plasma levels of insulin, blood glucose levels, and perivascular innervation were assessed using biochemical and immunohistochemical methods. Results FDR showed significant increase in plasma levels of insulin, an index for insulin resistance (Homeostasis Model Assessment ratio—HOMA-IR) and systolic blood pressure (SBP), but not blood glucose levels, as compared with control rats. Immunohistochemical study showed significantly greater density of tyrosine hydroxylase (TH)-like immunoreactivity (LI)-containing nerves and significantly lower density of calcitonin gene-related peptide (CGRP)-LI-containing nerves in mesenteric arteries of FDR than those in control. A 4-week treatment with ELE (500 and 1000 mg/kg, p.o.) significantly decreased plasma levels of insulin and HOMA-IR without affecting blood glucose levels and significantly lowered SBP in FDR. ELE treatment in FDR resulted in significant increase in CGRP-LI never fiber density and significant decrease in TH-LI never fiber density in mesenteric arteries of FDR. Conclusions These results suggest that long-term ELE treatment effectively prevents insulin resistance development and ameliorates abnormal perivascular innervation in FDR.

Intraspinal sprouting of unmyelinated pelvic afferents after complete spinal cord injury is correlated with autonomic dysreflexia induced by visceral pain

Autonomic dysreflexia is a potentially life-threatening hypertensive syndrome following high thoracic (T) spinal cord injury (SCI). It is commonly triggered by noxious pelvic stimuli below the injury site that correlates with increased sprouting of primary afferent C-fibers into the lumbosacral (L/S) spinal cord. We have recently demonstrated that injury-induced plasticity of (L/S) propriospinal neurons, which relay pelvic visceral sensations to thoracolumbar sympathetic preganglionic neurons, is also correlated with the development of this syndrome. To determine the phenotype of pelvic afferent fiber sprouts after SCI, cholera toxin subunit beta (CTb) was injected into the distal colon 2 weeks post–T4 transection/sham to label colonic visceral afferents. After 1 week of transport, the (L/S) spinal cords were cryosectioned and immunohistochemically stained for CTb, the nociceptive-specific marker calcitonin gene-related peptide (CGRP), and the myelinated fiber marker RT97. Quantitative analysis showed that the density of CGRP+ afferent fibers was significantly increased in the L/S dorsal horns of T4-transected versus sham rats, whereas RT97+ afferent fiber density showed no change. Importantly, CTb-labeled pelvic afferent fibers were co-localized with CGRP+ fibers, but not with RT97+ fibers. These results suggest that the sprouting of unmyelinated nociceptive pelvic afferents following high thoracic SCI, but not myelinated fibers, contributes to hypertensive autonomic dysreflexia induced by pelvic visceral pain.

Innervation and functional changes in mesenteric perivascular calcitonin gene-related peptide- and neuropeptide Y-containing nerves following topical phenol treatment

We have previously shown that age-related reduction of innervation and function in mesenteric perivascular calcitonin gene-related peptide-containing vasodilator nerves takes place in spontaneously hypertensive rats. The present study was performed to investigate innervation and functional changes in perivascular calcitonin gene-related peptide- and adrenergic neuropeptide Y-containing nerves after topical treatment with phenol, which damages nerve fibers, around the rat superior mesenteric artery. Under pentobarbital-Na anesthesia, 8-week-old Wistar rats underwent in vivo topical application of phenol (10% phenol in 90% ethanol) or saline (sham rats) to the superior mesenteric artery proximal to the bifurcation of the abdominal aorta. After the treatment, the animals were subjected to immunohistochemistry of the 3rd branch of small arteries proximal to the intestine and to vascular responsiveness testing on day 3 through day 14. The innervation levels of calcitonin gene-related peptide-like immunoreactivity containing fibers and neuropeptide Y-like immunoreactivity containing fibers were markedly reduced on day 3 to day 14 and on day 5 to day 14 after the treatment, compared with those in sham-operated rats, respectively. In perfused mesenteric vascular beds isolated from phenol-treated rats, adrenergic nerve-mediated vasoconstriction and calcitonin gene-related peptide nerve-mediated vasodilation in response to periarterial nerve stimulation (2–12 Hz) were significantly decreased on day 3 and day 7. Neurogenic release of norepinephrine in phenol-treated rats on day 7 was significantly smaller that that in sham-operated rats. Nerve growth factor content in the mesenteric arteries of phenol-treated rats was significantly lower than that in sham-operated rats. Administration of nerve growth factor using osmotic mini-pumps for 7 days after the phenol treatment resulted in greater density of calcitonin gene-related peptide- and neuropeptide Y-like immunoreactivity fibers than in phenol-treated rats and restored decreased vascular responses to periarterial nerve stimulation. These results suggest that topical phenol-treatment of the mesenteric artery effectively induces functional denervation of perivascular nerves, which can be prevented or reversed by nerve growth factor treatment.

Long-Term Inhibition of Angiotensin Prevents Reduction of Periarterial Innervation of Calcitonin Gene-Related Peptide (CGRP)-Containing Nerves in Spontaneously Hypertensive Rats

The aim of this study was to investigate age-related changes in the density of calcitonin gene-related peptide (CGRP)-containing nerve fibers in spontaneously hypertensive rats (SHR) and the effects of long-term inhibition of the renin-angiotensin system on these changes. The density of immunocytochemically stained nerve fibers in the mesenteric artery was quantified by computer-assisted image processing. An age-related decrease in the density of CGRP-like immunoreactive (LI)-containing nerve fivers but not neuropeptide Y (NPY)-LI-containing sympathetic nerve fibers was found in the mesenteric artery of SHR but not Wistar Kyoto rats (WKY). The density of NPY-LI-containing sympathetic nerve fibers was significantly greater in SHR than in WKY. SHR were treated for 7 weeks with angiotensin converting enzyme inhibitor (0.005% temocapril), angiotensin II type-1 (AT1) receptor antagonist (0.025% losartan) or vasodilator (0.01% hydralazine) in their drinking water. Each drug treatment significantly lowered the systolic blood pressure measured by tail-cuff method. Long-term treatment of SHR with temocapril and losartan significantly increased the density of CGRP-LI-containing nerve fibers in mesenteric arteries. However, the density after hydralazine treatment was similar to the level in non-treated SHR. The density of NPY-LI-containing nerve fibers was not increased by any of the drug treatments. These results suggest that long-term inhibition of the renin-angiotensin system in SHR prevents remodeling of CGRPergic nerve fibers and prevents the reduction of CGRPergic nerve function.

Alterations in neuropeptide expression in lumbosacral bladder pathways following chronic cystitis

These studies examined changes in the expression of calcitonin gene-related peptide (CGRP) and substance P (SP) in lumbosacral (L6-S1) micturition reflex pathways, following chronic cystitis induced by cyclophosphamide (CYP). In control Wistar rats, CGRP- or SP-immunoreactivity (IR) was expressed in fibers in the superficial dorsal horn in all segmental levels examined (L4-S1). Bladder afferent cells in the dorsal root ganglia (DRG; L6, S1) from control animals also exhibited CGRP- (41–55%) or SP-IR (2–3%). Following chronic, CYP-induced cystitis, CGRP- and SP-IR were dramatically increased in spinal segments and DRG (L6, S1) involved in micturition reflexes. The density of CGRP- and SP-IR was increased in the superficial laminae (I-II) of the L6 and S1 spinal segments. No changes in CGRP- or SP-IR were observed in the L4-L5 segments. Staining was also dramatically increased in a fiber bundle extending ventrally from Lissauer's tract in lamina I along the lateral edge of the DH to the sacral parasympathetic nucleus in the L6-S1 spinal segments. Following chronic cystitis, CGRP- and SP-IR in cells in the L6 and S1 DRG significantly ( P≤0.05) increased and the percentage of bladder afferent cells expressing CGRP- (76%) or SP-IR (11–18%) also significantly ( P≤0.001) increased. No changes were observed in the L4-L5 DRG. These studies suggest that the neuropeptides, CGRP and SP, may play a role in urinary bladder afferent pathways, following chronic urinary bladder inflammation. Changes in CGRP or SP expression following cystitis may contribute to the altered visceral sensation (allodynia) and/or urinary bladder hyperreflexia in the clinical syndrome, interstitial cystitis.

Change in Distribution and Density of CGRP, PGP 9.5, Serotonin and Chromogranin A Immunoreactivity in the Perinatal Rat Respiratory Tract.

Distribution and density of calcitonin gene-related peptide (CGRP), protein gene product (PGP) 9.5, serotonin and chromogranin A immunoreactivity were examined in developing rat respiratory tracts from embryonic day (ED) 15 to postnatal day (PD) 60. On ED 15, the epithelium of the primitive bronchi stained positively for CGRP, PGP 9.5, serotonin and chromogranin A. CGRP, PGP 9.5, serotonin and chromogranin A positive endocrine cells extended distally along the developing bronchial trees. Cell number reached a maximum on ED 19 or ED 17. On ED 21, the clusters of endocrine cells, identified as neuroepithelial bodies (NEBs) stained positively for either CGRP or PGP 9.5 in the bronchioles, and these were observed during all stages examined. CGRP or PGP 9.5 positive nerve fibers appeared during the Perinatal periods and increased in number after birth. However, neither serotonin nor chromogranin A immunoreactivity was observed in NEBs or nerve fibers in the airway at any of the examined developmental stages.

Influence of age and anti-nerve growth factor treatment on the sympathetic and sensory innervation of the rat iris.

We have investigated alterations in the nerve supply to the iris of aged rats and the role of endogenous nerve growth factor in these changes. The overall density of nerve fibres, and the density of calcitonin gene-related peptide containing sensory nerves, were decreased by over 20% on the aged iris, as measured by computerized image analysis on immunostained preparations, while the density of sympathetic innervation was maintained. Whilst the majority of nerves supplying the iris (sympathetic, sensory and parasympathetic) are known to respond to exogenous nerve growth factor during development and in adulthood, the role of endogenous, target-derived nerve growth factor in nerve maintenance in maturity and old age awaits confirmation. Our results showed that localized treatment with anti-nerve growth factor of iridial nerve terminals did not affect sympathetic or sensory neurons in young rats, but caused a dramatic reduction of sympathetic nerve density on irides of old rats. The effect of anti-nerve growth factor treatment on the sensory innervation of old irides was less obvious. We conclude that aged sympathetic nerves are more susceptible to nerve growth factor deprivation than young ones, or than young or aged sensory neurons, perhaps as a result of reduced responsiveness to nerve growth factor with age. Since sympathetic innervation is maintained, whilst sensory innervation is decreased in the aged iris, age-related changes in innervation are unlikely to be due to altered availability of endogenous nerve growth factor.

Role of gastric blood flow in impaired defense and repair of aged rat stomachs.

To study impaired gastric mucosal tolerance against noxious agents in aged rats, possible factors underlying this observation were compared in anesthetized Fisher 344 young and aged rats. The gastric mucosa was damaged by in situ exposure to 80% ethanol for 30-45 s and by 1 M NaCl for 10 min followed by saline (pH = 1.0) for 60 min in chambered stomachs. The lesion area was significantly larger and epithelial restitution was significantly slower in aged than in young rats after both types of injury. Changes in gastric blood flow were monitored by laser-Doppler velocimetry. Young, but not aged, rats showed a marked increase in gastric blood flow in response to 1 M NaCl, acid challenge, and 640 microM capsaicin for 60 min. Young rats showed a higher density of calcitonin gene-related peptide (CGRP)-staining nerve fibers around submucosal blood vessels and higher mucosal release of prostaglandin E2 and leukotriene C4 than did aged rats. These data suggest that impaired mucosal defense and reduced restitution in aged rats is related to lack of hyperemic response caused by mucosal injury and H+ back-diffusion, which is probably due to decreased density of CGRP-staining nerve fibers and prostaglandin biosynthetic capacity in the mucosa.

Lesion-induced changes in the central terminal distribution of galanin-immunoreactive axons in the dorsal column nuclei.

Rats that sustained forelimb removal on either embryonic day (E) 16, on the day of birth (P-0), or transection of the brachial plexus in adulthood had brainstem sections stained for galanin, calcitonin gene-related peptide (CGRP), or substance P (SP) at various intervals after these lesions were made. In normal adult rats, only a few galanin-immunoreactive fibers are present in the cuneate nucleus and most are located in its caudal portion. CGRP-positive axons are also sparse in the cuneate and are distributed mainly in the periphery of the nucleus. SP-positive axons are seen throughout the cuneate nucleus. In rats that sustained forelimb removals at birth or transection of the brachial plexus in adulthood, dense galanin immunoreactivity was present throughout the cuneate nucleus at all rostrocaudal levels on the side of the brainstem ipsilateral to the lesion. The changes after lesions that were made in the adult animals were apparent within 1 week, the earliest time analyzed. Increases in galanin immunoreactivity in the cuneate of animals that sustained forelimb removals on P-0 were first visible on P-2. Neither forelimb removal at birth nor brachial plexus lesions in adulthood had any qualitative effect upon the distribution or density of CGRP- or SP-immunoreactivity in the cuneate nucleus. Removal of a forelimb on E-16 did not increase the density of galanin-immunoreactive fibers in the cuneate nucleus. Such lesions also failed to produce any appreciable change in the density of either CGRP- or SP-positive fibers in the cuneate nucleus. The present data raise the possibility that large caliber, non-peptidergic primary afferent axons which innervate the cuneate nucleus may express galanin after damage at birth or in adulthood.