Brain-reactive autoantibodies in neuropsychiatric systemic lupus erythematosus

Introduction

The pathogenesis of neuropsychiatric systemic lupus erythematosus (NPSLE) is widely unknown, and the role of autoantibodies is still undetermined.

Methods

To identify brain-reactive autoantibodies possibly related to NPSLE, immunofluorescence (IF) and transmission electron microscopy (TEM) on rat and human brains were performed. ELISA was used to reveal the presence of known circulating autoantibodies, while western blot (WB) was applied to characterize potential unknown autoantigen(s).

Results

We enrolled 209 subjects, including patients affected by SLE (n=69), NPSLE (n=36), Multiple Sclerosis (MS, n=22), and 82 age- and gender-matched healthy donors (HD). Autoantibody reactivity by IF was observed in almost the entire rat brain (cortex, hippocampus, and cerebellum) using sera from NPSLE and SLE patients and was virtually negative in MS and HD. NPSLE showed higher prevalence (OR 2.4; p = 0.047), intensity, and titer of brain-reactive autoantibodies than SLE patients. Most of the patient sera with brain-reactive autoantibodies (75%) also stained human brains. Double staining experiments on rat brains mixing patients' sera with antibodies directed against neuronal (NeuN) or glial markers showed autoantibody reactivity restricted to NeuN-containing neurons. Using TEM, the targets of brain-reactive autoantibodies were located in the nuclei and, to a lesser extent, in the cytoplasm and mitochondria. Given the high degree of colocalization between NeuN and brain-reactive autoantibodies, we assumed NeuN was a possible autoantigen. However, WB analysis with HEK293T cell lysates expressing or not expressing the gene encoding for NeuN protein (RIBFOX3) showed that patients' sera carrying brain-reactive autoantibodies did not recognize the NeuN corresponding band size. Among the panel of NPSLE-associated autoantibodies (e.g., anti-NR2, anti-P-ribosomal protein, antiphospholipid) investigated by ELISA assay, only the anti-β2-glycoprotein-I (aβ2GPI) IgG was exclusively found in those sera containing brain-reactive autoantibodies.

Conclusion

In conclusion, SLE and NPSLE patients possess brain-reactive autoantibodies but with higher frequency and titers found in NPSLE patients. Although many target antigens of brain-reactive autoantibodies are still undetermined, they likely include β2GPI.

The Italian law on body donation: A position paper of the Italian College of Anatomists

In Italy, recent legislation (Law No. 10/2020) has tuned regulations concerning the donation of one's postmortem body and tissues for study, training, and scientific research purposes. This study discusses several specific issues to optimise the applicability and effectiveness of such an important, novel regulatory setting. Critical issues arise concerning the learners, the type of training and teaching activities that can be planned, the position of academic anatomy institutes, the role of family members in the donation process, the time frame of the donation process, the eligibility of partial donation, or the simultaneous donation of organs and tissues to patients awaiting transplantation. In particular, a universal time limit for donations (i.e., one year) makes it impossible to plan the long-term use of specific body parts, which could be effectively preserved for the advanced teaching and training of medical students and surgeons. The abovementioned conditions lead to the limited use of corpses, thus resulting in the inefficiency of the whole system of body donation. Overall, the donors' scope for the donation of their body could be best honoured by a more flexible and tuneable approach that can be used on a case-by-case basis. Furthermore, it is deemed necessary to closely monitor the events scheduled for corpses in public nonacademic institutions or private enterprises. This paper presents useful insights from Italian anatomists with the hope of providing inspiration for drafting the regulations. In conclusion, this paper focuses on the critical issues derived from the recently introduced Italian law on the donation and use of the body after death and provides suggestions to lawmakers for future implementations.

Telomere attrition and inflammatory load in severe psychiatric disorders and in response to psychotropic medications

Individuals with severe psychiatric disorders have a reduced life expectancy compared to the general population. At the biological level, patients with these disorders present features that suggest the involvement of accelerated aging, such as increased circulating inflammatory markers and shorter telomere length (TL). To date, the role of the interplay between inflammation and telomere dynamics in the pathophysiology of severe psychiatric disorders has been scarcely investigated. In this study we measured T-lymphocytes TL with quantitative fluorescent in situ hybridization (Q-FISH) and plasma levels of inflammatory markers in a cohort comprised of 40 patients with bipolar disorder (BD), 41 with schizophrenia (SZ), 37 with major depressive disorder (MDD), and 36 non-psychiatric controls (NPC). TL was shorter in SZ and in MDD compared to NPC, while it was longer in BD (model F6, 137 = 20.128, p = 8.73 × 10-17, effect of diagnosis, F3 = 31.870; p = 1.08 × 10-15). There was no effect of the different classes of psychotropic medications, while duration of treatment with mood stabilizers was associated with longer TL (Partial correlation controlled for age and BMI: correlation coefficient = 0.451; p = 0.001). Levels of high-sensitivity C-Reactive Protein (hsCRP) were higher in SZ compared to NPC (adjusted p = 0.027), and inversely correlated with TL in the whole sample (r = -0.180; p = 0.042). Compared to NPC, patients with treatment resistant (TR) SZ had shorter TL (p = 0.001), while patients with TR MDD had higher levels of tumor necrosis factor-α (TNFα) compared to NPC (p = 0.028) and to non-TR (p = 0.039). Comorbidity with cardio-metabolic disorders did not influence the observed differences in TL, hsCRP, and TNFα among the diagnostic groups. Our study suggests that patients with severe psychiatric disorders present reduced TL and increased inflammation.

Differences in telomere length between patients with bipolar disorder and controls are influenced by lithium treatment

Aim: To assess the role of lithium treatment in the relationship between bipolar disorder (BD) and leukocyte telomere length (LTL). Materials & methods: We compared LTL between 131 patients with BD, with or without a history of lithium treatment, and 336 controls. We tested the association between genetically determined LTL and BD in two large genome-wide association datasets. Results: Patients with BD with a history lithium treatment showed longer LTL compared with never-treated patients (p = 0.015), and similar LTL compared with controls. Patients never treated with lithium showed shorter LTL compared with controls (p = 0.029). Mendelian randomization analysis showed no association between BD and genetically determined LTL. Conclusion: Our data support previous findings showing that long-term lithium treatment might protect against telomere shortening.

A multidisciplinary approach to mental illness: do inflammation, telomere length and microbiota form a loop? A protocol for a cross-sectional study on the complex relationship between inflammation, telomere length, gut microbiota and psychiatric disorders

INTRODUCTION

Severe psychiatric disorders are typically associated with a significant reduction in life expectancy compared with the general population. Among the different hypotheses formulated to explain this observation, accelerated ageing has been increasingly recognised as the main culprit. At the same time, telomere shortening is becoming widely accepted as a proxy molecular marker of ageing. The present study aims to fill a gap in the literature by better defining the complex interaction/s between inflammation, age-related comorbidities, telomere shortening and gut microbiota in psychiatric disorders.

METHODS AND ANALYSIS

A cross-sectional study is proposed, recruiting 40 patients for each of three different diagnostic categories (bipolar disorder, schizophrenia and major depressive disorder) treated at the Section of Psychiatry and at the Unit of Clinical Pharmacology of the University Hospital Agency of Cagliari (Italy), compared with 40 age-matched and sex-matched non-psychiatric controls. Each group includes individuals suffering, or not, from age-related comorbidities, to account for the impact of these medical conditions on the biological make-up of recruited patients. The inflammatory state, microbiota composition and telomere length (TL) are assessed.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of the University Hospital Agency of Cagliari (PG/2018/11693, 5 September 2018). The study is conducted in accordance with the principles of good clinical practice and the Declaration of Helsinki, and in compliance with the relevant Italian national legislation. Written, informed consent is obtained from all participants. Participation in the study is on a voluntary basis only. Patients will be part of the dissemination phase of the study results, during which a local conference will be organised and families of patients will also be involved. Moreover, findings will be published in one or more research papers and presented at national and international conferences, in posters or oral communications.

BTK inhibitors synergise with 5-FU to treat drug-resistant TP53-null colon cancers

Colorectal cancer (CRC) is the fourth cause of death from cancer worldwide mainly due to the high incidence of drug-resistance. During a screen for new actionable targets in drug-resistant tumours we recently identified p65BTK - a novel oncogenic isoform of Bruton's tyrosine kinase. Studying three different cohorts of patients here we show that p65BTK expression correlates with histotype and cancer progression. Using drug-resistant TP53-null colon cancer cells as a model we demonstrated that p65BTK silencing or chemical inhibition overcame the 5-fluorouracil resistance of CRC cell lines and patient-derived organoids and significantly reduced the growth of xenografted tumours. Mechanistically, we show that blocking p65BTK in drug-resistant cells abolished a 5-FU-elicited TGFB1 protective response and triggered E2F-dependent apoptosis. Taken together, our data demonstrated that targeting p65BTK restores the apoptotic response to chemotherapy of drug-resistant CRCs and gives a proof-of-concept for suggesting the use of BTK inhibitors in combination with 5-FU as a novel therapeutic approach in CRC patients. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

p65BTK is a novel potential actionable target in KRAS-mutated/EGFR-wild type lung adenocarcinoma

BACKGROUND

Lung cancer is still the main cause of cancer death worldwide despite the availability of targeted therapies and immune-checkpoint inhibitors combined with chemotherapy. Cancer cell heterogeneity and primary or acquired resistance mechanisms cause the elusive behaviour of this cancer and new biomarkers and active drugs are urgently needed to overcome these limitations. p65BTK, a novel isoform of the Bruton Tyrosine Kinase may represent a new actionable target in non-small cell lung cancer (NSCLC).

METHODS

p65BTK expression was evaluated by immunohistochemistry in 382 NSCLC patients with complete clinico-pathological records including smoking habit, ALK and EGFR status, and in metastatic lymph nodes of 30 NSCLC patients. NSCLC cell lines mutated for p53 and/or a component of the RAS/MAPK pathway and primary lung cancer-derived cells from Kras/Trp53 null mice were used as a preclinical model. The effects of p65BTK inhibition by BTK Tyrosine Kinase Inhibitors (TKIs) (Ibrutinib, AVL-292, RN486) and first-generation EGFR-TKIs (Gefitinib, Erlotinib) on cell viability were evaluated by MTT. The effects of BTK-TKIs on cell growth and clonogenicity were assessed by crystal violet and colony assays, respectively. Cell toxicity assays were performed to study the effect of the combination of non-toxic concentrations of BTK-TKIs with EGFR-TKIs and standard-of-care (SOC) chemotherapy (Cisplatin, Gemcitabine, Pemetrexed).

RESULTS

p65BTK was significantly over-expressed in EGFR-wild type (wt) adenocarcinomas (AdC) from non-smoker patients and its expression was also preserved at the metastatic site. p65BTK was also over-expressed in cell lines mutated for KRAS or for a component of the RAS/MAPK pathway and in tumors from Kras/Trp53 null mice. BTK-TKIs were more effective than EGFR-TKIs in decreasing cancer cell viability and significantly impaired cell proliferation and clonogenicity. Moreover, non-toxic doses of BTK-TKIs re-sensitized drug-resistant NSCLC cell lines to both target- and SOC therapy, independently from EGFR/KRAS status.

CONCLUSIONS

p65BTK results as an emerging actionable target in non-smoking EGFR-wt AdC, also at advanced stages of disease. Notably, these patients are not eligible for EGFR-TKIs-based therapy due to a lack of EGFR mutation. The combination of BTK-TKIs with EGFR-TKIs is cytotoxic for EGFR-wt/KRAS-mutant/p53-null tumors and BTK-TKIs re-sensitizes drug-resistant NSCLC to SOC chemotherapy. Therefore, our data suggest that adding BTK-TKIs to SOC chemotherapy and EGFR-targeted therapy may open new avenues for clinical trials in currently untreatable NSCLC.

A novel oncogenic BTK isoform is overexpressed in colon cancers and required for RAS-mediated transformation

Bruton's tyrosine kinase (BTK) is essential for B-cell proliferation/differentiation and it is generally believed that its expression and function are limited to bone marrow-derived cells. Here, we report the identification and characterization of p65BTK, a novel isoform abundantly expressed in colon carcinoma cell lines and tumour tissue samples. p65BTK protein is expressed, through heterogeneous nuclear ribonucleoprotein K (hnRNPK)-dependent and internal ribosome entry site-driven translation, from a transcript containing an alternative first exon in the 5'-untranslated region, and is post-transcriptionally regulated, via hnRNPK, by the mitogen-activated protein kinase (MAPK) pathway. p65BTK is endowed with strong transforming activity that depends on active signal-regulated protein kinases-1/2 (ERK1/2) and its inhibition abolishes RAS transforming activity. Accordingly, p65BTK overexpression in colon cancer tissues correlates with ERK1/2 activation. Moreover, p65BTK inhibition affects growth and survival of colon cancer cells. Our data reveal that BTK, via p65BTK expression, is a novel and powerful oncogene acting downstream of the RAS/MAPK pathway and suggest that its targeting may be a promising therapeutic approach.

Abstract B121: A novel oncogenic BTK isoform is overexpressed in colon cancers and required for RAS-mediated transformation

It is known that Bruton's tyrosine kinase (BTK) is essential for B-cell proliferation/differentiation and it is generally believed that its expression and function are limited to bone marrow-derived cells. Here, we report the identification and characterization of p65BTK, a novel oncogenic isoform expressed in colon carcinomas.

Standard procedures were used for cloning the full length p65BTK-encoding mRNA and raise anti-p65BTK specific polyclonal antibodies. Quantitative PCR, western blot, RNA immunoprecipitation, silencing experiments and fluorescence assay upon transfection with bi-cistronic vectors were used to demonstrate post-transcriptional regulation of p65BTK expression. Immunohystochemistry was employed to study p65BTK expression in colon cancer patients specimens. Soft agar assay and foci assay were carried out to assess p65BTK oncogenic properties. Cell growth, cell viability and colony assays were performed to study the effects of p65BTK inhibition (by a specific kinase inhibitor) on colon cancer cells biology.

We found that p65BTK differs from the already known 77 kDa isoform for the lack of the N-terminal PH domain and is translated - through an IRES-dependent mechanism -from a transcript containing an alternative first exon in the 5'UTR. Moreover, p65BTK mRNA translation requires phosho-hnRNPK binding to its cognate sites (located in the alternative first exon) and is post-transcriptionally regulated, via hnRNPK, by the MAPK pathway. We demonstrate that p65BTK is endowed with strong transforming activity that depends on active ERK1/2 and its inhibition abolishes RAS transforming activity. Accordingly, p65BTK overexpression in colon cancer tissues correlates with ERK1/2 activation. Finally we show that p65BTK inhibition affects growth and survival of colon cancer cells.

In conclusion, our data reveal that BTK, via p65BTK expression, is a novel and powerful oncogene acting downstream of the RAS/MAPK pathway and suggest that its targeting may be a promising therapeutic approach.

Citation Format: Emanuela Grassilli, Fabio Pisano, Annamaria Cialdella, Sara Bonomo, Carola Missaglia, Maria Grazia Cerrito, Laura Masiero, Leonarda Ianzano, Robert Narloch, Filomena D'Amato, Barbara Noli, Gian Luca Ferri, Biagio E. Leone, Giorgio Stanta, Serena Bonin, Kristian Helin, Roberto Giovannoni, Marialuisa Lavitrano. A novel oncogenic BTK isoform is overexpressed in colon cancers and required for RAS-mediated transformation. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B121.

Temperature-driven nonclassical light

With reference to two well known scenarios, we discuss, for nonclassical light, the competition between quantum and thermal effects. It is seen that for nonclassical light to be produced some amount of temperature-induced disorder is needed plus quantum fluctuations of order ħ squared.

In vitro and in vivo pharmacological role of TLQP-21, a VGF-derived peptide, in the regulation of rat gastric motor functions

BACKGROUND AND PURPOSE

Vgf gene expression has been detected in various endocrine and neuronal cells in the gastrointestinal tract. In this study we investigated the pharmacological activity of different VGF-derived peptides. Among these, TLQP-21, corresponding to the 556-576 fragment of the protein was the unique active peptide, and its pharmacological profile was further studied.

EXPERIMENTAL APPROACH

The effects of TLQP-21 were examined in vitro by smooth muscle contraction in isolated preparations from the rat gastrointestinal tract and, in vivo, by assessing gastric emptying in rats. Rat stomach tissues were also processed for immunohistochemical and biochemical characterization.

KEY RESULTS

In rat longitudinal forestomach strips, TLQP-21 (100 nmol x L(-1)-10 micromol x L(-1)) concentration-dependently induced muscle contraction (in female rats, EC(50) = 0.47 micromol.L(-1), E(max): 85.7 +/- 7.9 and in male rats, 0.87 micromol x L(-1), E(max): 33.4 +/- 5.3; n = 8), by release of prostaglandin (PG)E(2) and PGF(2a) from the mucosal layer. This effect was significantly antagonized by indomethacin and selective inhibitors of either cyclooxygenase-1 (S560) or cyclooxygenase-2 (NS398). Immunostaining and biochemical studies confirmed the presence of VGF in the gastric neuronal cells. TLQP-21, injected i.c.v. (2-32 nmol per rat), significantly decreased gastric emptying by about 40%. This effect was significantly (P < 0.05) blocked by i.c.v. injection of indomethacin, suggesting that, also in vivo, this peptide acts in the brain stimulating PG release.

CONCLUSIONS AND IMPLICATIONS

The present results demonstrate that this VGF-derived peptide plays a central and local role in the regulation of rat gastric motor functions.

Pro-VGF-derived peptides induce penile erection in male rats: possible involvement of oxytocin

The effect of five peptides derived from the C-terminal portion of rat pro-VGF (VGF(577-617), VGF(588-617), VGF(599-617), VGF(556-576) and VGF(588-597)) on penile erection was studied after injection into the hypothalamic paraventricular nucleus of male rats. VGF(577-617), VGF(588-617), VGF(599-617) and, to a lower extent, VGF(588-597) (0.1-2 microg) induced penile erection episodes in a dose-dependent manner when injected into the paraventricular nucleus, while VGF(556-576) was ineffective. VGF(588-617)-induced penile erection was reduced by nitro(omega)-L-arginine methylester (L-NAME; 20 microg), by morphine (5 microg) and by muscimol (1 microg), but not by dizocilpine [(+)MK-801; 1 microg], nor by cis-flupenthixol (10 microg) given into the paraventricular nucleus 10 min before the VGF peptide. d(CH2)5Tyr(Me)-Orn8-vasotocin (1 microg) effectively reduced VGF(588-617)-induced penile erection when given into the lateral ventricles but not when injected into the paraventricular nucleus. Immunocytochemistry with antibodies specific for the C-terminal nonapeptide sequence of pro-VGF (VGF(609-617)) revealed numerous neuronal fibres and terminals within the paraventricular nucleus, including its parvocellular components. Here, many immunostained neuronal terminals impinged on parvocellular oxytocinergic neurons. The present results show for the first time that certain pro-VGF C-terminus-derived peptides promote penile erection when injected into the paraventricular nucleus and suggest that, within this nucleus, these or closely related pro-VGF-derived peptides may be released to influence sexual function by activating paraventricular oxytocinergic neurons mediating penile erection.

Isolation and characterization of VGF peptides in rat brain. Role of PC1/3 and PC2 in the maturation of VGF precursor

The neurotrophin responsive gene vgf is widely expressed in central and peripheral neurones, and in certain neuroendocrine cell populations. Its encoded VGF precursor protein (proVGF1: 617 amino acids in rat, 615 in man, > 85% homology) gives rise to several low molecular weight species. We studied a range of neuroendocrine and neuronal cells, in which VGF-processing products were prominent with an apparent molecular weight of 20 and 10 kDa (VGF20 and VGF10, respectively). Such peptides were recognized by antibodies specific for the C-terminal rat VGF nonapeptide, thus indicating that they included the C-terminus of proVGF. Ectopic expression of the neuroendocrine-specific prohormone convertases PC1/3 or PC2 in GH3 cells showed that both could generate VGF20, while VGF10 was preferentially produced by PC1/3. Site-directed mutagenesis was used to identify the KRKRKK(488) motif as the target within VGF sequence which leads to the production of VGF20. Molecular characterization of rat VGF10, on the other hand, revealed that this peptide is produced by cleavage at the RPR(555) site. By the combined use of high-resolution separation techniques, matrix-assisted laser desorption/ionization time of flight (MALDI-ToF) mass spectrometry and manual Edman degradation we identified in rat brain a VGF fragment analogous to bovine peptide V and two novel peptides also derived from the C-terminal region of proVGF.

VGF: a novel role for this neuronal and neuroendocrine polypeptide in the regulation of energy balance

Insight into the mechanisms of action of neurotrophic growth factors has been obtained through the identification and characterization of gene products that are regulated or modified at the transcriptional, translational, and/or posttranslational level in response to neurotrophin treatment. VGF (non-acronymic) was identified approximately 15 years ago as a nerve growth factor (NGF)-regulated transcript in rat PC12 pheochromocytoma cells. Subsequent studies have demonstrated that neurotrophins such as NGF and brain-derived neurotrophic factor induce vgf gene expression relatively rapidly in PC12 cells and cultured cortical neurons, respectively, in comparison to less robust regulation by epidermal growth factor (EGF) and insulin, growth factors which do not trigger the neuronal differentiation of PC12 cells. vgf gene expression is stimulated in vitro by NGF and the ras/map kinase signaling cascade through a CREB-dependent mechanism, while in vivo, VGF mRNA levels are regulated by neuronal activity, including long-term potentiation, seizure, and injury. Both the mRNA and encoded approximately 68-kDa protein (VGF) are selectively synthesized in neuroendocrine and neuronal cells. The predicted VGF sequence is rich in paired basic amino acid residues that are potential sites for proteolytic processing, and VGF undergoes regulated release from dense core secretory vesicles. Although VGF mRNA is synthesized widely, by neurons in the brain, spinal cord, and peripheral nervous system, its expression is particularly abundant in the hypothalamus. In addition, VGF peptides are found in hypophysial, adrenal medullary, gastrointestinal, and pancreatic endocrine cells, suggesting important neuroendocrine functions. Recent analysis of VGF knockout mice indeed demonstrates that VGF plays a critical role in the control of energy homeostasis. VGF knockout mice are thin, small, hypermetabolic, hyperactive, and relatively infertile, with markedly reduced leptin levels and fat stores and altered hypothalamic pro-opiomelanocortin, neuropeptide Y, and agouti-related peptide expression. Coupled with the demonstration that VGF mRNA levels are induced in the normal mouse hypothalamic arcuate nuclei in response to fasting, important central and peripheral roles for VGF in the regulation of metabolism are suggested. Here we review previous studies of VGF in the broader context of its newly recognized role in the control of energy balance and propose several models and experimental approaches that may better define the mechanisms of action of VGF.

Direct eye visualization of Cy5 fluorescence for immunocytochemistry and in situ hybridization

Cyanine 5.18 (or Cy5) is a fluorochrome emitting in the long-red/far-red range, usually regarded as unsuitable for direct observation by the human eye. We describe here the optimization of a direct visualization approach to Cy5 labeling, based on a standard fluorescence microscope with mercury light excitation and applicable to both immunocytochemistry and fluorescent in situ hybridization. Crucial factors were (a) an excitation path in the microscope not absorbing light in the orange-red range, up to 640 nm, (b) a 588-640-nm excitation filter range, distinctly below the excitation optimum for Cy5, (c) a 650-700-nm emission filter range, transmitting the low-wavelength portion of Cy5 emission, and (d) high-efficiency filter set components allowing a narrow gap between excitation and emission ranges without visible cross-talk of excitation light in the emission path.

Expression, processing, and secretion of the neuroendocrine VGF peptides by INS-1 cells

The neurotropin-inducible gene vgf is expressed in neuronal and endocrine tissues. It encodes a secretory protein that is proteolytically processed in neuronal cells to low molecular mass polypeptides. In the present report, we show that vgf is expressed in different insulinoma cell lines and in normal rat pancreatic islets. In the insulinoma-derived beta-cell line INS-1, vgf messenger RNA was transcriptionally up-regulated by increased levels ofintracellular cAMP, but not by the addition of glucose (20 mM) or phorbol 12-myristate 13-acetate (100 nM). Furthermore, nerve growth factor failed to stimulate vgf gene expression. In INS-1 cells, the VGF protein was shown to be processed in a post endoplasmic reticulum compartment to produce a peptide profile similar to that seen in neurons. The release of such VGF peptides occurred at a low rate in the absence of secretory stimuli (<2%/h). A 3-fold increase in the rate of release was seen after the addition of glucose (15 mM), a 4-fold increase was seen after (Bu)2cAMP (1 mM), and a 6-fold increase was seen after phorbol 12-myristate 13-acetate (100 nM). These results indicated that insulin-containing cells produce VGF-derived peptides that are released via a regulated pathway in response to insulin secretagogues.

Quadruple immunofluorescence: a direct visualization method

We describe fluorescence immunostaining of four different antigens in the same section. The fluorochrome conjugates used show highest emission in the blue, green, yellow, and red regions of the visible light spectrum, respectively. Specially designed single fluorochrome filter combinations allow selective visualization of each fluorochrome label in turn, without visible crosstalk with the others.

vgf A neurotrophin-inducible gene expressed in neuroendocrine tissues

vgf is an inducible gene, highly sensitive to nerve growth factor (NGF) and remarkably upregulated in the "early-delayed" phase of response (within a few hours). It encodes a 617-amino acid polypeptide (VGF protein) bearing no significant homology with known sequences and restricted to certain peptide/amine-producing endocrine cells, and neurons (for example, adenohypophysial and adrenal medullary cells, or hypothalamic neuroendocrine neurons). VGF is stored and transported in secretory granules and processed to intermediate-small molecular weight products, which are preferentially released. Striking changes in both VGF mRNA and immunolocalization are found in physiological conditions (for example, estrous cycle) and in experimental models of stimulation affecting hypothalamic and other neurons. Functional roles of VGF are to be sought in secretory granule formation and regulation, and/or in the production of potentially bioactive peptides.

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates adenylate cyclase and promotes proliferation of mouse primordial germ cells

During migration and for about 2 days after their arrival in the gonadal ridges, primordial germ cells (the embryonic precursors of gametes of the adult animal) proliferate actively. Certain growth factors, such as stem cell factor and leukemia inhibitory factor, seem to be essential for survival, proliferation and possibly differentiation of mouse primordial germ cell in vivo and/or in vitro. Similarly, increase in intracellular cAMP is followed by a marked enhancement of primordial germ cell proliferation, at least in culture. In the present study, we show that pituitary adenylate cyclase-activating polypeptides (PACAP-27 and PACAP-38), two neuropeptides of the secretin-glucagon-vasoactive intestinal polypeptide-GH-releasing hormone family, stimulate in vitro proliferation of mouse primordial germ cells, bind to primordial germ cells and gonadal somatic cells (possibly to type I PACAP receptor) and activate adenylate cyclase in the same cells. Moreover, PACAP-like immunoreactivity was found in gonadal ridges, mostly on germ cell surface. In conclusion, evidence is provided that PGC proliferation can be stimulated by certain bioactive polypeptides, thus suggesting a novel regulatory role for such compounds in early gonad development.

Tissue-specific processing of the neuroendocrine protein VGF

VGF is a neuroendocrine-specific gene product that is up-regulated by nerve growth factor in the PC12 cell line. In rat neuroendocrine tissues two polypeptides of 90 and 80 kDa were detected by an antiserum to an N-terminal domain of VGF (from residues 4 to 240). In parallel, an antiserum directed against the C-terminal nonapeptide of VGF (from residues 609 to 617) revealed several additional posttranslational products. Peptides of apparent molecular sizes of 20, 18, and 10 kDa were prominent in nerve tissues and the hypophysis but absent in the adrenal medulla, and their relative abundance varied in distinct regions of the CNS. In PC12 cells VGF was proteolytically processed only after nerve growth factor treatment, and primary cultures of rat cerebellar granule cells accumulated the low-molecular-weight forms of VGF during in vitro maturation. In these cells the specific cleavages of VGF occurred in a postendoplasmic reticulum compartment; the processed forms were enriched in the secretory vesicles and were preferentially secreted upon cell membrane depolarization. Distinct differential distribution in the CNS and in vitro release of such posttranslational products indicate that these species may represent biologically relevant forms of VGF that play a role in neuronal communication.

The "VGF" protein in rat adenohypophysis: sex differences and changes during the estrous cycle and after gonadectomy

Gene expression and cell localization of the neuroendocrine protein VGF were studied in the rat anterior pituitary. In females, four antisera against nonoverlapping regions of VGF immunostained a small number of lactotropes and many gonadotropes. In the latter cells, VGF immunoreactivity was localized to a subpopulation of secretory granules. Distinct changes were seen after estrus, with a significant increase in VGF messenger RNA (whole pituitary), whereas VGF immunostaining was strikingly reduced in gonadotropes and somewhat more abundant in lactotropes. In male rats, gene expression was low, and immunoreactivity was restricted to a few lactotropes. After castration or ovariectomy, VGF messenger RNA was high, and VGF immunoreactivity was abundant in gonadotropes. Selective localization and cyclic modulation suggest involvement of the VGF gene product(s) in pituitary gonadotrope and/or lactotrope function.

Experimental beta beta'-iminodipropionitrile (IDPN) neuropathy: neurofilament profile of sensory, motor and autonomic nerves as seen by immunocytochemistry on whole-mount preparations

IDPN-induced changes in a variety of sensory, motor and autonomic nerves were studied by whole-mount immunocytochemistry. A full range of proximo-distal accumulations of neurofilament-like material was found, from paranuclear round bodies in perikarya to distal and preterminal axonal dilations. Conversely, both terminal areas and nodal-paranodal regions of myelinated axons showed striking, sharply localized loss of neurofilament-immunostaining. The latter change, when transport of neurofilaments is halted by IDPN, may indicate their local processing and/or differential transport at nodal-paranodal regions.

Rectospinal neurons: cell bodies, pathways, immunocytochemistry and ultrastructure

A novel class of enteric neurons projecting directly from the rectal wall to the spinal cord, "rectospinal neurons", was investigated in rats by combined retrograde neuronal tracing, immunocytochemistry and electron microscopy. Rectospinal neurons were almost confined to myenteric ganglia of the distal rectum below the pelvic diaphragm and were labeled preferentially by injections into spinal cord segments L6/S1. Injections into more rostral spinal cord segments resulted in hardly any labeled enteric neurons. Dorsal and ventral rhizotomy experiments indicated an almost exclusive projection of rectospinal neurons through dorsal roots L6/S1 to the respective spinal cord segments. Among various peptides immunostained, vasoactive intestinal polypeptide and calcitonin gene-related peptide were selectively found in rectospinal neurons, which were also shown to contain calbindin, neurofilament protein- and peripherin-immunoreactivity. Vasoactive intestinal polypeptide- and calbindin-immunostaining were frequently co-localized in the same perikarya, while calcitonin gene-related peptide-immunoreactive rectospinal neurons probably represented a separate population. Neonatal capsaicin treatment did not significantly reduce the number of rectospinal neurons. Electron microscopy revealed synaptic contacts on the surface of rectospinal neurons. Taken together, these results establish rectospinal neurons as an anatomically and neurochemically distinct class of enteric neurons. Synaptic contacts on rectospinal neurons suggest that these neurons may function as a direct link from the enteric to the central nervous system, thus indicating that connections between these two networks are reciprocal.

A novel neuroendocrine gene product: selective VGF8a gene expression and immuno-localisation of the VGF protein in endocrine and neuronal populations

The VGF8a gene was recognised on the basis of its inducibility by NGF in rat pheochromocytoma (PC12) cells. Using immunocytochemistry, we have localised the corresponding VGF protein product in various neuronal groups, including primary sensory and enteric neurons, and in endocrine cells of the adrenal medulla, adenohypophysis and gut. VGF8a gene expression, as detected by RNAse protection analysis, largely correlated with such distribution.

Heterogeneous visceral nerve changes in acrylamide intoxication

A variety of visceral nerves were studied by intermediate filament immunocytochemistry in rats intoxicated with acrylamide. In such animals, oesophageal and diaphragmatic motor end-plates were invaded and deformed by neurofilament protein-like material, while afferent fibres of diaphragmatic neuromuscular spindles and myelinated sensory fibres of the iris showed striking terminal accumulation of similar material. Conversely, the rich population of thin afferent fibres of the iris showed no obvious abnormality, while pre-terminal changes were seen along the extrinsic nerve fibres supplying the cornea and myenteric ganglia. Multiple lesions were demonstrated in gut nerves of acrylamide-treated rats, while scattered "enteric glial cells" showed abnormally coarse morphology and a striking increase in glial fibrillary acidic protein immunoreactivity. A distinct, delicately varicose appearance was revealed by neurofilament protein-immunostaining in bladder nerve fibres of normal rats, which was changed to one of coarse dilations by acrylamide. In conclusion, apparently selective changes were found along different types of axons, indicating marked heterogeneity in cytoskeletal organisation among visceral nerves. Taken together with the proposed inhibition by acrylamide of neurofilament proteins degradation, the above findings may suggest a non-uniform distribution of neurofilament degradation sites along distal regions of different axons.

Acrylamide-induced visceral neuropathy: evidence for the involvement of capsaicin-sensitive nerves of the rat urinary bladder

The mechanisms underlying the severe urinary retention induced by acrylamide intoxication were studied in detail in the rat. Subcutaneous treatment with acrylamide monomer (50 mg/kg daily for 10 days) almost completely impaired the micturition reflex, resulting in urinary retention. In fact, the ability to eliminate an oral water load was virtually abolished, while bladder filling with saline (transvesical cystometrogram) failed to activate reflex micturition. Instead, a picture of overflow incontinence resulted in urethane-anaesthetized rats, which was not reversed by intravenous administration of 4-aminopyridine. The nerve-mediated contractile response to field stimulation (0.1-20 Hz, 0.5 ms, 60 V) of the isolated bladder was unaffected, thus suggesting the integrity of bladder efferent innervation, and no evidence was found from in vitro experiments that the myogenic contractility of the bladder was depressed by acrylamide treatment. Conversely, the sensory nerve-mediated response to capsaicin was abolished and sensory nerve fibres of the bladder were selectively depleted of their content of substance P- and calcitonin gene-related peptide immunoreactivity following acrylamide treatment. In fact, concentrations of the same neuropeptides in other organs, including the adjoining ureters, were unaffected. As to the urethral segment, including the striated sphincter, the D-tubocurarine (0.2 mM)-sensitive urethral response to electrical stimulation (0.1 Hz, 0.1 ms, 20 V) was significantly reduced in acrylamide-treated animals. At the same level, neurofilament protein immunostaining revealed striking accumulations of neurofilament protein-like material in motor end-plates, thus indicating that neuromuscular junctions of the urethral striated sphincter were severely affected. Thus, the afferent arm of the micturition reflex was shown to be severely deranged by acrylamide intoxication, especially in its capsaicin-sensitive component. Since twitch-like contractions of the urethral striated sphincter are probably involved in promoting bladder voiding, a decreased efficiency of this mechanism could participate in the picture of urinary retention induced by acrylamide.

Involvement of capsaicin-sensitive nerves of the rat urinary bladder in acrylamide neuropathy

Acrylamide monomer is neurotoxic in man and experimental animals, producing a sensorimotor distal axonopathy. In spite of remarkable effect of acrylamide on micturition, resulting in urine retention in both man and rat, bladder autonomic innervation has been little studied. This study focused on the effect of acrylamide on capsaicin-sensitive nerves of the rat bladder, because of the role played by these fibres in regulating the afferent arm of reflex micturition.

Neuronal intermediate filaments in rat dorsal root ganglia: differential distribution of peripherin and neurofilament protein immunoreactivity and effect of capsaicin

Two major neuronal populations were revealed in rat dorsal root ganglia, immunoreactive for either peripherin, or neurofilament triplet proteins (adult L2 ganglia: 66.2% and 25.6%, mainly small and large diameter cells, respectively), together with a minor, double-immunostained population (L2: 8.1%, mainly intermediate-size neurons). After capsaicin treatment, a striking expansion in the latter population was seen (L2: 22.0%) together with a significant increase in size, restricted to the same population and the (remaining) peripherin-only immunoreactive neurons. Calcitonin gene-related peptide (CGRP) immunoreactivity was revealed in neurons of all 3 groups, in both normal and capsaicin-treated rats.

Intramural distribution of immunoreactive vasoactive intestinal polypeptide (VIP), substance P, somatostatin and mammalian bombesin in the oesophago-gastro-pyloric region of the human gut

The intramural distribution of vasoactive intestinal polypeptide (VIP), substance P, somatostatin and mammalian bombesin was studied in the oesophago-gastro-pyloric region of the human gut. At each of 21 sampling sites encompassing this entire area, the gut wall was separated into mucosa, submucosa and muscularis externa, and extracted for radioimmunoassay. VIP levels in the mucosa were very high in the proximal oesophagus (1231 +/- 174 pmol/g, mean +/- SEM) and showed varied, but generally decreasing concentrations towards the stomach, followed by a clear-cut increase across the pyloric canal (distal antrum: 73 +/- 16 pmol/g, proximal duodenum: 366 +/- 62 pmol/g); consistent levels were found in submucosa and muscle (200-400 pmol/g) at most sites, the stomach again showing lower concentrations. By contrast, substance P was present in small amounts as far as the proximal stomach, but sharply increased across the pyloric canal, especially in mucosa and submucosa (distal antrum: 20 +/- 6.5 and 5.5 +/- 1.3 pmol/g; proximal duodenum: 62 +/- 8.5 and 34 +/- 11 pmol/g, respectively). Somatostatin concentrations were very low in the mucosa of the oesophagus and stepwise increased in the cardiac, mid-gastric and pyloric mucosa (cardia: 224 +/- 72 pmol/g; distal antrum: 513 +/- 152 pmol/g; proximal duodenum: 1013 +/- 113 pmol/g); concentrations in the submucosa and muscularis were generally low, with the exception of antrum and duodenum. Mammalian bombesin was comparatively well represented throughout the oesophageal muscularis (5-8 pmol/g), but most abundant in the stomach in all layers (oxyntic mucosa: 24 +/- 2.7 pmol/g; submucosa: 20 +/- 5.7 pmol/g; muscle: 28 +/- 5.0 pmol/g).(ABSTRACT TRUNCATED AT 250 WORDS)

Morphometry of peptide-containing nerves in gut muscle layers: a quantitative approach to the study of autonomic neuro-muscular junctions

A method for the quantitative assessment of peptide-containing nerves in the gastrointestinal muscle layers is described. Tissue samples are sectioned obliquely, at 45 degrees, in the plane bisecting the long axes of longitudinal and circular muscle fibres, and peptide-containing nerve fascicles are revealed by immunofluorescence. Cross-sectioned fascicles are counted (number/area of muscle) and their length density per volume of muscle layer is calculated. The composition of immunostained nerve fascicles is also assessed, by counting peptide-containing fibres in each, while peptide transmitter co-distributions are studied in parallel using adjacent tissue sections. Thus, the approach described provides a means for the delineation of both quantitative tissue distribution and composition of autonomic neuro-muscular junctions in the gastro-intestinal tract.

Proenkephalin A-derived peptides in the human gut

The intramural distribution of the proenkephalin A-derived peptides Leu5-enkephalin, Met5-enkephalin, Met5-enkephalin-Arg6-Phe7, and Met5-enkephalin-Arg6-Gly7-Leu8 was studied throughout the human gastrointestinal tract. A parallel distribution was found of Leu5/Met5-enkephalin, measured with a Leu5-enkephalin antiserum that cross-reacts about 30% with Met5-enkephalin, and of Met5-enkephalin-Arg6-Phe7-immunoreactivity and Met5-enkephalin-Arg6-Gly7-Leu8-immunoreactivity. In each case, high tissue concentrations were present in the submucosa and muscularis corresponding to the pyloric sphincter. Taking all different regions together, a high correlation was revealed between tissue levels of Leu5/Met5-enkephalinlike peptides and Met5-enkephalin-Arg6-Gly7-Leu8-like peptides (r = 0.89), as well as between Met5-enkephalin-Arg6-Gly7-Leu8-like peptides and Met5-enkephalin-Arg6-Phe7-like peptides (r = 0.75). Met5-enkephalin-Arg6-Phe7 immunoreactivity was accounted for by a major peak (87% +/- 3% of total immunoreactivity) coeluting with the standard peptide in Sephadex G-50 chromatography and largely composed of the authentic heptapeptide, as shown by reverse-phase high-performance liquid chromatography. Leu5/Met5-enkephalin immunoreactivity was separated by high-performance liquid chromatography into peaks composed of Leu5-enkephalin and Met5-enkephalin. Allowing for Met5-enkephalin immunoreactivity in the assay used, the apparent Leu5/Met5-enkephalin molecular ratio was approximately 1:4. The high concentration of all peptides studied at the pyloric junction suggests a rich enkephalin-containing innervation at this level, in keeping with the proposed involvement of an enkephalinergic mechanism in the control of pyloric function.

Intramural distribution of regulatory peptides in the sigmoid-recto-anal region of the human gut

The distribution of regulatory peptides was studied in the separated mucosa, submucosa and muscularis externa taken at 10 sampling sites encompassing the whole human sigmoid colon (five sites), rectum (two sites), and anal canal (three sites). Consistently high concentrations of VIP were measured in the muscle layer at most sites (proximal sigmoid: 286 (16) pmol/g, upper rectum: 269 (17), a moderate decrease being found in the distal smooth sphincter (151 (30) pmol/g). Values are expressed as mean (SE). Conversely, substance P concentrations showed an obvious decline in the recto-anal muscle (mid sigmoid: 19 (2.0) pmol/g, distal rectum: 7.1 (1.3), upper anal canal: 1.6 (0.6)). Somatostatin was mainly present in the sigmoid mucosa and submucosa (37 (9.3) and 15 (3.5) pmol/g, respectively) and showed low, but consistent concentrations in the muscle (mid sigmoid: 2.2 (0.7) pmol/g, upper anal canal: 1.5 (0.8]. Starting in the distal sigmoid colon, a distinct peak of tissue NPY was revealed, which was most striking in the muscle (of mid sigmoid: 16 (3.9) pmol/g, upper rectum: 47 (7.8), anal sphincter: 58 (14)). Peptide YY was confined to the mucosa and showed an earlier peak (upper sigmoid: 709 (186) pmol/g, mid-distal sigmoid: 1965 (484)). A clear differential distribution of regulatory peptides was thus shown in the region studied. A possible role is suggested for NPY and VIP containing nerves in the effector control of the human internal anal sphincter.

Distribution of a novel pituitary protein (7B2) in mammalian gastrointestinal tract and pancreas

The distribution of a novel pituitary protein (7B2) was determined in the gastrointestinal tract and pancreas of four mammalian species (man, pig, guinea pig, and rat) by a specific radioimmunoassay. The highest concentrations of cross-reacting immunoreactive 7B2 (IR-7B2) were observed in the pancreas and the proximal gut (antrum or duodenum). While the intestinal concentrations varied widely among species, pancreatic IR-7B2 concentrations appeared to be similar in all four species. In the rat, pancreatic islets were found to contain high concentrations of IR-7B2 (5.73 +/- 0.14 fmol/islet, mean +/- SEM). Neonatal capsaicin treatment and enteric nerve section did not affect the concentrations of IR-7B2 in the rat intestine. Layer separation of human gut showed that IR-7B2 is mainly (71 +/- 8%) present in the epithelial fraction. Chromatographic analysis of intestinal and pancreatic extracts from the four species on Sephadex G-100 showed the presence of two immunoreactive peaks at Kav 0.3 and 0.6, but there were both inter- and intraspecies variations in the proportions of the larger and smaller molecular forms.

Regional distribution of immunoreactive dynorphin A in the human gastrointestinal tract

Immunoreactive dynorphin A (ir-Dyn A) was detected throughout the human gastrointestinal tract by a validated radioimmunoassay. Moreover, the stability of 125I-Dyn A during extraction procedures was confirmed by high performance liquid chromatography. Levels of ir-Dyn A were higher in the stomach and in the small bowel. In tissue samples separated into the main layers composing the gut wall (muscularis externa, submucosa and mucosa) ir-Dyn A was uniformly distributed. An exception was the colon, where concentrations were higher in the muscular portion. Gel permeation chromatography on samples of mucosa and muscularis externa extracts of ileum and gastric fundus, showed immunoreactive material eluting in several forms of apparently higher molecular weight than Dyn A, while only a minor peak was found to coelute with authentic Dyn A.

2,5-Hexanedione-induced accumulations of neurofilament-immunoreactive material throughout the rat autonomic nervous system

In rats intoxicated with 2,5-hexanedione, nerve fibres supplying virtually all visceral organs showed large numbers of densely immunoreactive accumulations of neurofilament-like material, of fusiform, elongated, smoothly tapering morphology. In the gut, round to oval, morphologically different lesions were also present, and abnormal neurofilament-immunoreactive accumulations were revealed in oesophageal terminal end-plates. An extensive damage to autonomic nerve fibres, which are largely non-myelinated, was thus revealed in 2,5-hexanedione intoxication. The observed diversity in lesion morphology may suggest heterogeneity in cytoskeletal and/or associated proteins among autonomic neurons.

Intramural distribution of regulatory peptides in the human stomach and duodenum

The distribution of regulatory peptides was studied by radioimmunoassay in the separated mucosa, submucosa and muscularis externa of the human oxyntic stomach, antrum and duodenum. Immunoreactive gastrin, secretin, gastric inhibitory polypeptide and motilin were virtually confined to the mucosa and duodenal submucosa, where endocrine cells are present. Only minor amounts of motilin and gastrin (3.2 +/- 0.5% and 4.3 +/- 0.8% of their total content, means + SEM, respectively) were found in the separated duodenal muscle. Somatostatin-, vasoactive intestinal polypeptide-, substance P-, and mammalian bombesin-like peptides showed distinct differential distributions in all layers. Substance P was low in the stomach and markedly increased in the duodenum, especially in the mucosa (fundus 0.8 +/- 0.2 pmol/g, duodenum 66 +/- 12). Vasoactive intestinal polypeptide and somatostatin, although well represented in the stomach, also increased in the duodenum in all layers of the wall (whole fundus 281 +/- 33 and 334 +/- 46 pmol/g, antrum 124 +/- 18 and 426 +/- 59, duodenum 507 +/- 99 and 1816 +/- 149, respectively). Mammalian bombesin immunoreactivity was comparatively abundant in the oxyntic stomach (mucosa 34 +/- 4.5 pmol/g, muscularis externa 29 +/- 4.8), less so in the antrum (6.3 +/- 1.5 and 11 +/- 3.2 pmol/g, respectively). Low concentrations of this peptide were measured in the duodenum, practically confined to the muscle (this layer 5.1 +/- 1.5 pmol/g, or 83 +/- 5.6% of the total content).

Intramural distribution of Met5-enkephalin-Arg6-Gly7-Leu8 in sphincter regions of the human gut

The intramural distribution of Met5-enkephalin-Arg6-Gly7-Leu8 (MERGL) was studied in the oesophago-cardiac, pyloric, ileo-caecal and sigmoid-recto-anal regions of the human digestive tract. Serial samples encompassing each area were separated into mucosa, submucosa and muscularis externa and extracted for radioimmunoassay. Comparatively low levels of MERGL immunoreactivity were measured throughout the cardiac junction. Conversely, a remarkable peak of MERGL concentration was detected at the pyloric junction, in both submucosa and muscularis. A progressive decrease in tissue levels of the same peptide, most evident in the submucosa, was detected on the proximal side of the ileo-caecal region. In the distal sigmoid colon and rectum MERGL concentrations showed a rapid decline, down to very low levels in the anal canal. The results may suggest the involvement of an enkephalinergic mechanism in the control of the human pylorus.

Regulatory peptide distribution in separated layers of the human jejunum

The distribution of regulatory peptides was studied in the separated epithelium, lamina propria, submucosa and muscularis externa of the human jejunum. Gastrin, secretin, gastric inhibitory polypeptide, enteroglucagon and neurotensin immunoreactivity were almost confined to the endocrine cell-containing mucosal epithelium (greater than 98% of the total content), only minor amounts of motilin being detected in non-epithelial layers (3.6 +/- 0.7%, mean +/- SEM, n = 7). Conversely, vasoactive intestinal polypeptide, substance P and mammalian bombesin were virtually limited to non-epithelial layers (greater than 99%). Only somatostatin was found in all layers (44 +/- 6.7% in the epithelium, 34 +/- 5.2% in the lamina propria, 13 +/- 2.9% in the submucosa, and 7.9 +/- 2.8% in the muscularis). Substance P was found in higher concentrations in the mucosa, compared to submucosa and muscle (56 +/- 10, 30 +/- 4.0 and 29 +/- 4.0 pmol/g, respectively), while vasoactive intestinal polypeptide was more abundant in the muscle (411 +/- 52 pmol/g) compared to mucosa and submucosa (228 +/- 64 and 219 +/- 31 pmol/g, respectively). Only low levels of mammalian bombesin were measured, mainly in the muscle (6.9 +/- 1.5 pmol/g, or 89 +/- 3.6% of total content).

Distribution and molecular heterogeneity of galanin in human, pig, guinea pig, and rat gastrointestinal tracts

Galanin was measured by radioimmunoassay in whole thickness extracts of the gastrointestinal wall from four species and in extracts from separate layers of human small intestine. The immunoreactivity was characterized using gel chromatography and high-pressure liquid chromatography. Two antibodies were employed, which were characterized as non-C-terminal (Gal 8) and C-terminal (Gal 9) using a C-terminal galanin 10-29 fragment. Substantial quantities of galanin immunoreactivity were found, mainly localized at the muscle layer. Both intramolecular and intermolecular heterogeneity was apparent. Two molecular forms exist in humans (Kav 0.58, 0.69). The molecular heterogeneity in humans, rats, and guinea pigs may be localized near the C-terminus of the galanin molecule. A C-terminal extension of one human galanin form is likely (Kav 0.58). These findings give radioimmunologic evidence for a neurocrine origin of galanin. The chromatographic variations suggest that extrapolation of experimental results between species should be treated with caution.

Met5-enkephalin-Arg6-Gly7-Leu8 immunoreactivity in the human gut

The presence of the proenkephalin A-derived peptide Met5-enkephalin-Arg6-Gly7-Leu8 was demonstrated throughout the human gastrointestinal tract. Highest concentrations of Met5-enkephalin-Arg6-Gly7-Leu8, as assessed by radioimmunoassay, were measured in the separated muscularis externa, while lower levels were found in the submucosa and only small amounts in the mucosa. The results are consistent with a neuronal location of this peptide in the human gut. Over 65% of total immunoreactivity coeluted with the authentic peptide in both molecular exclusion chromatography and HPLC, while most of the remainder activity eluted earlier on gel filtration. The latter material probably represents N-terminally extended Met5-enkephalin-Arg6-Gly7-Leu8. Taken together with previous studies, our results appear to indicate that there are important species differences in post-translational processing of proenkephalin A in gut nerves.

Human distribution and release of a putative new gut hormone, peptide YY

A radioimmunoassay has been developed for the new intestinal hormonal peptide tyrosine tyrosine [peptide YY (PYY)]. Peptide YY concentrations were measured in separated layers of the human gastrointestinal tract, where PYY was found exclusively in the mucosal epithelium which contained the endocrine cells. Peptide YY was found throughout the small intestine, in very low concentrations (5 pmol/g) in duodenum (6 pmol/g) and jejunum (5 pmol/g), but in higher concentrations in the terminal ileum (84 pmol/g). High concentrations were found throughout the colon (ascending 82 pmol/g, sigmoid 196 pmol/g), being maximum in the rectum (480 pmol/g). The major molecular form of PYY-like immunoreactivity in human intestine appeared to be identical to pure porcine hormone, both as judged by gel permeation chromatography and by reverse-phase high-pressure liquid chromatography. Basal plasma concentrations of PYY were low but rose in response to food, remaining elevated for several hours postprandially. The known potent biologic actions of PYY, its high concentrations in gut endocrine cells, and its release into the circulation after a normal meal suggest that this peptide may function physiologically as a circulating gut hormone.

The effects of ileal transposition and jejunoileal bypass on food intake and GI hormone levels in rats

Male Wistar rats received three different types of small intestinal surgery. Two groups of rats had either 10 or 20 cm of lower ileum transposed to mid-duodenum. A third comparison group of rats had 85% jejunoileal bypass. All three experimental groups showed a sustained post-operative reduction in food intake and a change in body weight gain. Measurements made 36 days after surgery showed that all experimental groups had a large increase in basal and meal-stimulated enteroglucagon. The total-integrated plasma levels of gastrin, GIP, insulin and blood glucose were significantly reduced. At sacrifice, there were large increases in the wet weight of the small intestine and pancreas. These changes were probably due to the chronic stimulation of the lower ileum with nutrient-rich chyme and may be due to the release of ileal hormones.

VIP-, substance P- and met-enkephalin-immunoreactive innervation of the human gastroduodenal mucosa and Brunner's glands

VIP-, substance P- and met-enkephalin-containing innervation of the human gastroduodenal mucosa and Brunner's glands was studied by immunocytochemistry on whole mount tissue preparations. A dense VIP-containing nerve supply was found around fundic and pyloric glands, while the few and scattered substance P-immunoreactive fibres tended to run across the full thickness of the gastric mucosa. In the duodenum, both VIP and substance P were present in a striking nerve network in the villi as well as in the muscularis mucosae and around blood vessels. Both peptides were also immunostained in nerve bundles and neuronal perikarya between the lobules of Brunner's glands, while only very few fibres reached the proximity of acinar cells. Met-enkephalin-immunoreactivity was detected in a small number of nerve fibres, virtually confined to the basal parts of the mucosa and to the duodenal submucous plexus.

Quantification of the intestinal peptide-containing innervation: length density of nerve fibers and total length of nerve supply to the single villus/crypt unit

The application of a morphometric method to the quantification of peptide-containing nerves in the gut is described. It allows a simple estimation of the nerve fiber supply per unit volume of tissue (length density) and the calculation of the total nerve fiber supply per unit of intestinal mucosa (villus/crypt unit).

Immunocytochemistry of serotonin-containing nerves in the human gut

An immunocytochemical technique, using L-tryptophan enhancement and paraformaldehyde fixation, has been successfully applied for the demonstration of serotonin-containing neurons in the human enteric nervous system. Throughout the intestine, serotonin-immunoreactive nerves were mainly detected in the myenteric plexus and, to a smaller extent, in the submucous plexus, while hardly any nerve fibres were seen in the mucosa. This approach provides a useful tool for the investigation of neuropathological conditions of the gut.

Immunocytochemical evidence for the presence of gamma 1-MSH-like immunoreactivity in pituitary corticotrophs and ACTH-producing tumours

The presence of gamma 1-MSH has been demonstrated in bovine neuro-intermediate lobe by biochemical methods, thus suggesting that this peptide is cleaved from the cryptic region of pro-opiocortin. In this study we report the localisation of gamma 1-MSH-like immunoreactivity in the adenohypophysis of man, ox, pig, dog and guinea-pig using immunocytochemical procedures at both light and electron microscope levels. Antisera recognising the C-terminal Arg-Phe-amide and the C-terminal penta-peptide-amide of gamma 1-MSH have been used throughout this study. The immunostaining was found in all endocrine cells of the pars intermedia (where present) and in scattered cells of the pars distalis identified as corticotrophs. No gamma 1-MSH immunoreactivity was detected in rat adenohypophysis. In addition, 7 ACTH-producing tumours (1 pituitary adenoma and 6 ectopic) were investigated and shown to contain gamma 1-MSH immunoreactive cells.