Neurotensin. Immunohistochemical localization in central and peripheral nervous system and in endocrine cells and its functional role as neurotransmitter and endocrine hormone

The present study attempts to compile information on the possible physiologic role of the endogenous peptide neurotensin (NT) as a hormone and/or neurotransmitter. The methodological approach is immunohistochemical localization of NT in the entero-endocrine system as well as in the central and peripheral nervous systems. The results found in the three systems are first related to the pharmalogical and physiological findings in the literature. Subsequently their significance is discussed for each organ separately before attempting a final overall interpretation. Briefly, the present study reveals the following essential findings: The occurrence and distribution of NT-IR entero-endocrine cells (N-cells) in different mammals including man, as well as in representative members of all classes of vertebrates and higher invertebrates, are analyzed and evaluated morphometrically. The NT-IR cells in all investigated species are demonstrated to be of the open type. The innervation of paravertebral and prevertebral ganglia by NT-IR fibers is described; at least a portion of these fibers is thought to originate in NT-IR perikarya of the substantia intermedia of the spinal cord. The involvement of these NT-IR fibers in the regulation of systemic blood flow (hypertension) is suggested. The existence of NT-IR innervation of the gastro-intestinal tract is considered to be a general phenomenon. This notion is reaffirmed by phylogenetic investigation of the NT-IR enteric nerves. The pharmacological effects of NT in different portions of the gastro-intestinal tract, reported in the literature are related to the immunohistochemical localization of NT. In light of the present results, some of the effects of NT which were previously considered to be of an endocrine or paracrine nature - such as contraction of the guinea-pig ileum - are interpreted as effects of NT of neuronal origin. The specific NT-IR innervation of target cells in the exocrine pancreas (vascular smooth muscle, acinar cells) is demonstrated, and participation of NT-IR nerve fibers in regulation of the secretion of pancreatic juice is postulated. The innervation of the heart (coronary vasculature, myocardium, conduction system) by NT-IR fibers is demonstrated in various mammals and for the first time also in man. The cardiac NT-IR nerve fibers are thought to be the cytological substrate for different NT effects on heart action (coronary vasoconstriction, positive inotropy and chronotropy) reported in the literature.(ABSTRACT TRUNCATED AT 400 WORDS)     

Neuropeptide (neuropeptide Y,neurotensin, vasoactive intestinal polypeptide,substance P,calcitonin gene-related peptide,somatostatin) immunohistochemistry and ultrastructure of renal nerves

Summary With the use of several region-specific antisera and the peroxidase-antiperoxidase (PAP) technique, several regulatory polypeptides were localized in nerves of the kidney. Neuropeptide Y (NPY)- immunoreactivity (IR), neurotensin (NT)-IR and vasoactive intestinal polypeptide (VIP)-IR occurred at high densities in all segments of the renal arterial system forming a perivascular plexus. Furthermore, NT-IR nerves were particularly frequent at the juxtaglomerular apparatus (JGA). Calcitonin gene-related peptide (CGRP)-IR was mainly concentrated in nerves supplying the hilus arteries and the JGA. Substance P (SP)-IR was predominantly found in large varicosities close to large renal arterial vessels and in the vicinity of the JGA. Somatostatin (SOM)-IR was only observed in single varicosities located at the media-adventitia border of large renal hilus arteries. The peptidergic nerves are correlated to their ultrastructural counterpart. In addition, the distribution patterns and the frequency of the different types of renal peptidergic nerve fibres are evaluated and compared. The functional role of these neuropeptides and their origin within the efferent branch of this part of the peripheral autonomic nervous system is discussed. Furthermore, the implication of some of the neuropeptides studied in afferent renal innervation is also substantiated.Dedicated to Prof. Dr. T.H. Schiebler on the occasion of his 65th birthday     

Oxidation of Indole-3-Acetic Acid to Oxindole-3-Acetic Acid by an Enzyme Preparation from Zea mays

Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity. A heat-stable, detergent-extractable component from corn enhances enzyme activity 6- to 10-fold. This is the first demonstration of the in vitro enzymic oxidation of indole-3-acetic acid to oxindole-3-acetic acid in higher plants.     

Substance P-immunoreactive neurons in the brainstem of the cat related to cardiovascular centers

Summary The distribution of substance P-immunoreactivity (SP-IR) in the brainstem and spinal cord of normal and colchicine-pretreated cats was analysed using the peroxidase-antiperoxidase (PAP) technique. Numerous SP-IR fibers are present in the nucleus solitarius, nucleus dorsalis nervi vagi and nucleus spinalis nervi trigemini, various parts of the formatio reticularis, substantia grisea centralis mesencephali, locus coeruleus and nucleus parabrachialis. SP-IR perikarya occur in the substantiae gelatinosa and intermedia of the spinal cord, the nucleus spinalis nervi trigemini-pars caudalis, the nucleus dorsalis nervi vagi, and the nucleus solitarius, as well as in the adjacent formatio reticularis and the medullary nuclei of the raphe. In addition, SP-IR cell bodies are located in the nuclei raphe magnus and incertus, ventral and dorsal to the nucleus tegmentalis dorsalis (Gudden), nucleus raphe dorsalis, substantia grisea centralis mensencephali, locus coeruleus, nucleus parabrachialis and colliculus superior.The results indicate that SP-IR neurons may be involved in the regulation of cardiovascular functions both at the central and peripheral level. A peripheral afferent portion seems to terminate in the nucleus solitarius and an efferent part is postulated to originate from the nucleus dorsalis nervi vagi and from the area of the nuclei retroambiguus, ambiguus and retrofacialis.     

Toxicity to Earthworms and Chemical Composition of Oil Refinery Sludge Destined for Landfarming

For landfarming of oil refinery waste to be sustainable, it is crucial to know the toxicity and chemical composition of the waste. We determined the chemical composition of waste known as American Petroleum Institute sludge and tested its toxicity in two different soils using the earthworm Eisenia andrei (Oligochaeta) in standardized bioassays. We compared the chemical composition of the sludge with available chemical profiles of the landfarming site where sludge of the same origin had been landfarmed for several years. The concentrations of Al, Mn, Pb, S and Zn and diesel range organics were higher in the landfarmed soil than in the sludge, indicating possible accumulation in the soil over time. Although no traces of volatile organic compounds were previously found in the landfarming site soil, we found high levels in the American Petroleum Institute sludge, indicating that these volatiles may not pose a long-term problem in the soil. Polycyclic aromatic hydrocarbons and gasoline range organics were present in the sludge at higher concentrations than in the site soil, indicating that their remediation through landfarming may have had some degree of success.

Earthworm biomass and reproduction were detrimentally affected at low sludge concentrations, which could have population level effects over time in a landfarming site.     

The endocytic recycling compartment maintains cargo segregation acquired upon exit from the sorting endosome

The endocytic recycling compartment (ERC) is a series of perinuclear tubular and vesicular membranes that regulates recycling to the plasma membrane. Despite evidence that cargo is sorted at the early/sorting endosome (SE), whether cargo mixes downstream at the ERC or remains segregated is an unanswered question. Here we use three-dimensional (3D) structured illumination microscopy and dual-channel and 3D direct stochastic optical reconstruction microscopy (dSTORM) to obtain new information about ERC morphology and cargo segregation. We show that cargo internalized either via clathrin-mediated endocytosis (CME) or independently of clathrin (CIE) remains segregated in the ERC, likely on distinct carriers. This suggests that no further sorting occurs upon cargo exit from SE. Moreover, 3D dSTORM data support a model in which some but not all ERC vesicles are tethered by contiguous “membrane bridges.” Furthermore, tubular recycling endosomes preferentially traffic CIE cargo and may originate from SE membranes. These findings support a significantly altered model for endocytic recycling in mammalian cells in which sorting occurs in peripheral endosomes and segregation is maintained at the ERC.     

Metabolic risks at birth of neonates exposed in utero to HIV-antiretroviral therapy relative to unexposed neonates: an NMR metabolomics study of cord blood

Introduction

Antiretroviral therapy (ART) for HIV-infected pregnant women is highly effective in preventing mother-to-child transmission (PMTCT) of the virus, but deleterious metabolic and mitochondrial observations in infants born to HIV-infected women treated with ART during pregnancy are periodically reported.

Objectives

This study addresses the concern of HIV-ART-induced metabolic perturbations through a metabolomics study of cord blood collected during transitional neonatal hypoglycaemia following birth from newborns either exposed or unexposed to fetal HIV-ART.

Methods

Proton magnetic resonance spectra from cord blood of 11 in utero HIV-ART-exposed and 14 unexposed newborns, as well as serum from 8 control infants, generated 114 spectral bins which were used to identify significant metabolites by means of univariate and multivariate statistical analyses.

Results

The metabolite profiles differed significantly between that from the unexposed newborns and that from infants—interpreted to characterize the state of transitional neonatal hypoglycaemia (low glucose and high lactic acid and ketone bodies). Quantitative analysis of potential ATP generation showed no meaningful difference in the global metabolite profiles of HIV-ART-exposed and unexposed neonates, but Volcano plot analysis, affirmed by odds ratios, indicated that exposure to HIV-ART affected the plasma 3-hydroxybutyric acid and hypoxanthine concentrations.

Conclusions

The metabolite profile for transitional neonatal hypoglycaemia indicated that HIV-ART did not compromise the exposed neonates to the energy stress of allostasis experienced at birth. Increased hypoxanthine and 3-hydroxybutyric acid indicates metabolic stress at birth in some of the newborns exposed to HIV-ART and raises a concern about unrecognized prolonged allostasis with potential neurological consequences for these infants.

     

Visceral muscles and myogenic activity in the hindgut of the cockroach,Leucophaea maderae

Summary The hindgut of the Madeira cockroach contains an intricate network of longitudinal and circular muscles that are distinctive for each region. In the rectum, the longitudinal muscles are symmetrically arranged in 6 distinct bands, while the circular muscles appear as a uniform layer over the rectal pads. In the colon, the muscle fibers are arranged in an irregular lattice with the longitudinal fibers generally superimposed on the circular ones but with an evident weaving between the layers. In addition to these muscle layers, a delicate, superficial network of muscle-like fibers covers many portions of the colon and rectum.In spite of the bewilderingly complex motile activity of deganglionated hindguts, all activity could be classified under 4 basic types after cinematographic analysis: segmentation, compression, peristalsis, or reverse peristalsis or a combination thereof. Although much of the activity that occurred was seemingly random, there was an evident rhythmicity that spontaneously arose and ended in several types of motility during the course of observations. The defined modes of activity seemed to be completely myogenic in nature, as all 4 categories were readily observed in hindguts 30 min after treatment with tetrodotoxin (10^–6 g/ml). Each region of the hindgut seemed to have its own particular rhythm.Action potentials were recorded both intracellularly and extracellularly from all regions of the hindgut; amplitude usually ranged between 10 and 20 mV for intracellular recordings, and such spike potentials were often preceded by a slow depolarizing pre-potential. Generally, however, the depolarization was abrupt. Transmembrane potentials from the visceral muscle fibers were never truly at rest. Slow, continuous fluctuations (3–8 mV) were common. At times, plateau-type action potentials were recorded, but generally the repolarization contour was almost linear with time. Contractions were evoked by action potentials but not by the slow, rhythmic fluctuations in the membrane potential.No particular region or structure in the hindgut showed an exclusive pacemaker function. However, there was an evident gradient of increased excitability progressing in an caudal direction from the ileum.In a sodium-free saline, the amplitude of action potentials was remarkable enhanced from 5 to 10 min after the initial change. Even after a 20 min exposure, action potentials were still often present although their frequency and amplitude dropped. Tetrodotoxin (10^–6g/ml) had no. pronounced effect on frequency or amplitude of action potentials. However, spike potentials ceased within 1.5 min after exposure to a sodium and calcium-free saline. When such preparations were re-exposed to a sodium-free saline containing normal calcium, the action potentials reappeared, suggesting that calcium might be a current-carrying ion. Although action potentials in a calcium-free medium showed variability, we generally saw a marked reduction in amplitude of potentials within 5 min. We further observed that 2 mM manganous ion completely abolished action potentials within 2 min. Thus, it seems likely that sodium is not the sole current-carrying ion in cockroach hindgut muscle.The authors express their indebtedness to Ms. Susan Swann, Mr. Gerald Holt, Mr. David Owens, and Ms. Mary Strand for their competent technical assistance.