The Role of Galanin during Bacterial Infection in Larval Zebrafish.

Galanin is a peptide that is conserved among different species and plays various roles in an organism, although its entire role is not completely understood. For many years, galanin has been linked mainly with the neurotransmission in the nervous system; however, recent reports underline its role in immunity. Zebrafish (Danio rerio) is an intensively developing animal model to study infectious diseases. In this study, we used larval zebrafish to determine the role of galanin in bacterial infection. We showed that knockout of galanin in zebrafish leads to a higher bacterial burden and mortality during Mycobacterium marinum and Staphylococcus aureus infection, whereas administration of a galanin analogue, NAX 5055, improves the ability of fish to control the infection caused by both pathogens. Moreover, the transcriptomics data revealed that a lower number of genes were regulated in response to mycobacterial infection in gal-/- mutants compared with their gal+/+ wild-type counterparts. We also found that galanin deficiency led to significant changes in immune-related pathways, mostly connected with cytokine and chemokine functions. The results show that galanin acts not only as a neurotransmitter but is also involved in immune response to bacterial infections, demonstrating the complexity of the neuroendocrine system and its possible connection with immunity.

Protective Role of Galanin during Chemically Induced Inflammation in Zebrafish Larvae.

During a pathological condition, many different systems are involved in the response of an affected organism. Galanin is considered to be a neuropeptide that plays an important role in the central nervous system; however, it is involved in many other biological processes, including the immune response. During our studies, we showed that galanin became upregulated in zebrafish larvae when exposed to copper sulfate. Moreover, the presence of normal levels of galanin, administration of a galanin analog NAX 5055 or galanin overexpression led to lowered lateral line damage and enhanced expression of inflammatory markers compared to the knockout larvae. The results showed that the neuroendocrine system acts multifunctionally and should be considered as a part of the complex neuro-immune-endocrine axis.

The effect of Khat (Catha edulis) as an appetite suppressant is independent of ghrelin and PYY secretion.

BACKGROUND: The leaves of the khat plant (Catha edulis) are chewed for their pleasurable effects. Chewing releases cathinone which may decrease appetite through an unknown mechanism. Levels of the peptide ghrelin increase with hunger and decrease immediately post-prandially, while peptide YY is released following a meal. We hypothesised that the anorexigenic effects of khat may be mediated through changes in these hormones. MATERIALS AND METHODS: Six habitual khat chewers attended on two separate occasions. For a period of 3h they chewed either khat leaves or lettuce. Blood pressure (BP) and pulse rate (PR) were monitored throughout, as were subjective assessments of hunger and fullness. Plasma samples were analysed for cathinone, ghrelin and PYY levels. RESULTS: Chewing khat significantly decreased subjective feelings of hunger and increased fullness (p<0.05) but had no effect on ghrelin and PYY levels. Khat led to an increase in cathinone levels as well as an increase in BP and PR. Cathinone levels correlated positively with fullness and pulse rate and negatively with hunger. CONCLUSIONS: Chewing khat decreases subjective feelings of hunger and increases systemic sympathetic tone, but has no effect on ghrelin and PYY levels. We conclude that the anorexigenic effect of khat may be secondary to central mechanisms mediated via cathinone.

Chemical derivatization and mass spectral libraries in metabolic profiling by GC/MS and LC/MS/MS.

An overview is presented of gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS), the two major hyphenated techniques employed in metabolic profiling that complement direct 'fingerprinting' methods such as atmospheric pressure ionization (API) quadrupole time-of-flight MS, API Fourier transform MS, and NMR. In GC/MS, the analytes are normally derivatized prior to analysis in order to reduce their polarity and facilitate chromatographic separation. The electron ionization mass spectra obtained are reproducible and suitable for library matching, mass spectral collections being readily available. In LC/MS, derivatization and library matching are at an early stage of development and mini-reviews are provided. Chemical derivatization can dramatically increase the sensitivity and specificity of LC/MS methods for less polar compounds and provides additional structural information. The potential of derivatization for metabolic profiling in LC/MS is demonstrated by the enhanced analysis of plant extracts, including the potential to measure volatile acids such as formic acid, difficult to achieve by GC/MS. The important role of mass spectral library creation and usage in these techniques is discussed and illustrated by examples.

BSE control: detection of gelatine-derived peptides in animal feed by mass spectrometry.

The epidemic of bovine spongiform encephalopathy (BSE) is thought to have resulted from feeding scrapie-infected sheep to cattle. This has led to a ban of feeding animals with "processed animal protein"(PAP). We report a novel approach for the mass spectrometric detection of PAP contamination in animal feedstuffs by detecting gelatine, a derivative of the major animal protein collagen. A method was developed to hydrolyse gelatine standards with hydrochloric acid, followed by detection of the derived hydrolytic peptides at m/z 828, 915, 957 and 1044 by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS-MS). The marker peptides can be detected at concentrations of 100 ng ml(-1) gelatine in water with MALDI. The procedure was adapted to obtain a suitable peptide map of gelatine extracted from spiked feed. The ratio of signal area of the gelatine-derived peptide at m/z 1044 to the internal standard at m/z 556 is shown to relate to the total amount of gelatine present in the sample.