Calcitonin gene-related peptide: Brain and spinal action on intestinal motility

The effects of intracerebroventricular (ICV) and intrathecal (IT) administration of calcitonin gene-related peptide (CGRP) on intestinal motility were examined in conscious rats chronically fitted with intraparietal electrodes in the duodeno-jejunum and a cannula in a cerebral lateral ventricle or catheter in the subarachnoid space. ICV administration of CGRP (0.5–10 μg) restores the fasted pattern of intestinal motility in fed rats in a dose-related manner. Intrathecal administration of CGRP or calcitonin also induces fasted pattern but after a 30 min delay. These effects persisted after transection of the spinal cord and no change in intestinal motility appeared after intravenous administration of CGRP at a dose effective when given IT. This study suggests that CGRP, as calcitonin, has a neuromodulatory role in the control of intestinal motility at both brain and spinal cord levels.     

Effect of calcitonin gene-related peptide on the neuroeffector mechanism of sympathetic nerve terminals in rat vas deferens

In order to evaluate the mode of action of calcitonin gene-related peptide (CGRP) on the neuroeffector mechanism of peripheral sympathetic nerve fibers, the effects of CGRP were tested on the electrical stimulated and the non-stimulated preparations of the isolated rat vas deferens. The contractile responses, which were mediated predominantly by activation of postganglionic noradrenergic nerve fibers, were dose-dependently inhibited by CGRP in concentrations ranging from 0.1 to 10 nM. The inhibitory response produced by CGRP in high concentrations (greater than 2 nM) usually returned to the control level at 20-30 min and were rarely tachyphylactic. The inhibitory action of CGRP was not modified by pretreatment with 10(-7) M propranolol or 10(-7) M atropine. Contractions produced by exogenous norepinephrine (NE) and 5-hydroxytryptamine (5-HT) in unstimulated preparations were not affected by pretreatment with CGRP in a low concentration (less than 2 nM). On the other hand, the contractions were slightly reduced 1 min after pretreatment with CGRP in high concentrations (greater than 5 nM), which recovered in 15 min after constant flow washout. High concentrations of CGRP also caused a concentration-dependent relaxation on the precontracted preparations produced by high potassium (60 mM K+) solution. These results suggest that CGRP in high concentrations (greater than 5 nM) may have a non-specific inhibitory action on the postsynaptic plasma membrane of the smooth muscle cell and a postulated CGRP receptor exists presynaptically in the rat vas deferens and that CGRP may inhibit the release of NE during adrenergic nerve stimulation.     

Hypermotility induced by vasoactive intestinal peptide in the rat: its reciprocal action to cholecystokinin octapeptide

Intracerebroventricular administration of vasoactive intestinal peptide (VIP) shortened the duration of pentobarbital-induced sleep and produced significant hypermotility in the rat. Although hypermotility induced by methamphetamine was not potentiated by central administration of VIP, L-DOPA-induced hypermotility in pargyline-pretreated rats was markedly enhanced by VIP and this hypermotility was suppressed by simultaneous administration of cholecystokinin octapeptide (CCK-8) in a dose-related manner. Apomorphine-induced hypermotility was also potentiated by VIP. These results suggest that VIP may stimulate postsynaptic dopaminergic receptor, causing an increase in motility, and that a possible reciprocal interaction exists between VIP and CCK-8.     

Calcitonin gene-related peptide: detailed immunohistochemical distribution in the central nervous system

With the use of an antiserum generated in rabbits against synthetic human calcitonin gene-related peptide (CGRP) the distribution of CGRP-like immunoreactive cell bodies and nerve fibers was studied in the rat central nervous system. A detailed stereotaxic atlas of CGRP-like neurons was prepared. CGRP-like immunoreactivity was widely distributed in the rat central nervous system. CGRP positive cell bodies were observed in the preoptic area and hypothalamus (medial preoptic, periventricular, anterior hypothalamic nuclei, perifornical area, medial forebrain bundle), premamillary nucleus, amygdala medialis, hippocampus and dentate gyrus, central gray and the ventromedial nucleus of the thalamus. In the midbrain a large cluster of cells was contained in the peripeduncular area ventral to the medial geniculate body. In the hindbrain cholinergic motor nuclei (III, IV, V, VI, VII XII) contained CGRP-immunoreactivity. Cell bodies were also observed in the ventral tegmental nucleus, the parabrachial nuclei, superior olive and nucleus ambiguus. The ventral horn cells of the spinal cord, the trigeminal and dorsal root ganglia also contained CGRP-immunoreactivity. Dense accumulations of fibers were observed in the amydala centralis, caudal portion of the caudate putamen, sensory trigeminal area, substantia gelatinosa, dorsal horn of the spinal cord (laminae I and II). Other areas containing CGRP-immunoreactive fibers are the septal area, nucleus of the stria terminalis, preoptic and hypothalamic nuclei (e.g., medial preoptic, periventricular, dorsomedial, median eminence), medial forebrain bundle, central gray, medial geniculate body, peripeduncular area, interpeduncular nucleus, cochlear nucleus, parabrachial nuclei, superior olive, nucleus tractus solitarii, and in the confines of clusters of cell bodies. Some fibers were also noted in the anterior and posterior pituitary and the sensory ganglia. As with other newly described brain neuropeptides it can only be conjectured that CGRP has a neuroregulatory action on a variety of functions throughout the brain and spinal cord.     

Effect of 6-hydroxydopamine on neuropeptides in the rat female genitourinary tract

The occurrence and distribution of neuropeptide Y has been determined in the rat female genitourinary tract by radioimmunoassay and chromatographic analysis. Within the bladder, higher concentrations of neuropeptide Y were found in the trigone (48.8±5.2 pmol/g) than in the dome (36.0±2.1 pmol/g). In the genital tract, highest concentrations were identified in the vagina (41.4±2.1 pmol/g). Treatment of rats with 6-hydroxydopamine resulted in significant depletion of neuropeptide Y concentrations in both parts of the bladder, together with vagina, uterine horn and fallopian tube. No change was observed in the cervix, uterine body and ovary. Concentrations of vasoactive intestinal polypeptide were unaffected by treatment with 6-hydroxydopamine except in the area of the cervix where concentrations rose from 64.1±5.7 pmol/g to 133.6±15.1 pmol/g (p<0.05). There was a generalised, but statistically insignificant rise in substance P concentrations.     

Induction of autolysis of staphylococci by the basic peptide antibiotics Pep 5 and nisin and their influence on the activity of autolytic enzymes

Pep 5 and nisin are cationic bactericidal peptides which were shown to induce autolysis in Staphylococcus cohnii 22. In contrast to nisin, Pep 5 induced lysis could be stimulated in the presence of glucose. Addition of lipoteichoic acids (LTA) (d-alanine:phosphorus=0.475:1) inhibited all effects of Pep 5 on susceptible cells in a molar ratio LTA:Pep 5 of 10:1. Treatment of S. cohnii 22 with Pep 5 or nisin for 20 min and subsequent washing with 2.5 M NaCl released autolysin activity. Crude preparations of the hydrolyzing enzymes produced free amino groups as well as polysaccharide fragments from the murein backbone, suggesting the presence of a muramidase or glucosamidase, and endopeptidase or amidase. Both enzyme activities were inhibited by lipoteichoic acid; they could be fully reactivated by addition of Pep 5 in sufficient concentrations. The velocity of hydrolysis was not influenced by nisin, whereas it was doubled in presence of Pep 5. The results are discussed in view of a possible mechanism of induction of lysis by Pep 5 and nisin.Abbreviations A.U. arbitrary unit - CCCP carbonylcyanide-m-chlorophenyl hydrazone - DNase deoxyribonuclease - CYG casein yeast extract glucose - IT initial turbidity - LTA lipoteichoic acid - RNase ribonuclease - TSB Tryptone Soy Broth     

Glutathione-S-transferase,a possible drug-metabolizing enzyme,in Haemonchus contortus: Comparative activity of a cambendazole-resistant and a susceptible strain

Kawalek J. C., Rew R. S. and Heavner J. 1984. Glutathione-S-transferase, a possible drug-metabolizing enzyme in Haemonchus contortus: comparative activity of a cambendazole-resistant and a susceptible strain. International Journal for Parasitology14: 173–175. A drug metabolizing enzyme (DME), glutathione-S-transferase, was detected in homogenates of a cambendazole-susceptible and a cambendazole-resistant strain of Haemonchus contortus. The activity was 1.5–1.8 times higher in the resistant strain. DME activation is a possible mechanism for anthelmintic resistance in H. contortus.     

大熊猫乳酸脱氢酶同工酶M_4胰酶水解后的HPLC肽谱分析

 比较了大熊猫与猪LDH-M_4用胰酶水解后的HPLC肽谱;对分离出的各个肽段测定了氨基酸组成与N-末端。经分析,在两者各有的35个肽段中,22个肽段有相同的氨基酸组成与N-末端且在HPLC图谱上有相同的保留时间。另外有13个肽段在氨基酸组成与保留时间上存在差异。对大熊猫LDH-M中部分肽段测定了氨基酸残基序列。结果表明,与结合NAD~+有关的12肽的序列与一级结构已知的猪LDH-M含有Cys165的相应肽段完全一样;在与底物结合部位含有His191的35肽中,两者只有一个氨基酸残基的差异。在N-端的21肽中,有3个残基出现差异;而在C-端的14肽中,仅出现一个残基的差异。     

Characterization of a membrane-specific tubulin isoform by peptide mapping

A membrane-specific tubulin-like protein, found in preparations of synaptic plasma membranes and brain mitochondria, was analyzed by chemical and proteolytic peptide mapping to determine which part of the molecule was different from cytoplasmic tubulin. The membrane polypeptide was identical to alpha tubulin in the first two-thirds of the molecule containing the amino terminal, as found by peptide mapping. However, some differences were observed in the peptide maps of the carboxy terminal one third of the molecule which includes a domain that is important in the regulation of tubulin self-assembly.     

Interaction of a bovine thymic peptide extract with vasoactive intestinal peptide (VIP) receptors

Bovine t hymic peptide extract (1–100 g/ml) is shown to completely inhibit the binding of [¹²⁵I]VIP to rat blood mononuclear cells, lymphoid cells of spleen, and liver plasma membranes. In the three models, the bovine thymic peptide extract inhibits [¹²⁵I]VIP binding with a potency that is 4000–7000 times lower than that of the native VIP, on a weight basis. In rat liver plasma membranes, the bovine thymic peptide extract stimulates adenylate cyclase with a maximal efficiency that is similar to that of VIP. At maximal doses, VIP and thymic peptide extract do not exert an additive effect on adenylate cyclase, suggesting that the activation of the enzyme by the bovine thymic peptide extract occurs through VIP receptors. Finally, no VIP-like immunoreactivity was detected in the thymic peptide extract using an antiserum raised against mammalian VIP. All these data suggest the presence in the bovine thymic peptide extract of a new substance which behaves as a VIP agonist in rat.