Biogenic Amines in the Vomeronasal Organ

The vomeronasal organ of frog and mouse was investigated forthe presence and content of serotonin and catecholamines bymeans of high-performance liquid chromatography. Measurableamounts of serotonin, adrenaline and noradrenaline were foundin the vomeronasal organ of adult individuals of both species.The amine content varied with sex of adult frogs and mice andsexual maturity of mice. In preliminary experiments, acute exposureto male urine containing pheromone affected the amine contentin the vomeronasal organ of adult female mice. These data suggestthat functional sex dimorphism is present in the vomeronasalorgan, and biochemical changes therein take place accordingto stage of sexual maturity. The role of biogenic amines inthe vomeronasal organ deserves further study. Chem. Senses 22:439–445, 1997.     

Biogenic Amines in the Taste Organ

The presence and content of biogenic amines in taste disk-bearingfungiform papillae of the frog, Rana esculenta, the only availablemodel of an isolated taste organ, were verified by means ofHPLC. Fungiform papillae were found to contain measurable amountsof serotonin, epinephrine and norepinephrine. The amounts ofserotonin and epinephrine were significantly higher in fungiformpapillae than in the general mucosa of the tongue. Moreover,the epinephrine content of fungiform papillae was found to differacross the tongue, in accordance with previous physiologicalstudies showing an inhomogeneous response of different tongueregions to taste stimuli. Ultrastructural and histochemicalinvestigations confirmed the presence of catecholamine and serotonin.The latter was found to be contained mainly in the basal cellsof the frog taste disk. These results extend previous qualitativedata on the presence of biogenic amines in taste chemoreceptors.Chem. Senses 20: 329–335, 1995.     

The Localization of Biogenic Amines in the Echinopluteus

The distribution of biogenic amines in the young pluteus of Psammechinus miliaris Gmelin was examined by means of the histochemical fluorescence method of Falck and Hillarp. Two different systems where monoamines occur were detected. Catecholamines were mainly found in a presumably impulse propagating neuron-like system, while 5-HT (serotonin) was predominantly localized in the endoderm wall. The results are discussed in relation to the ontogeny and phylogeny of sea urchins.     

Dietary Folate and Biogenic Amines in the CNS

Abnormal biogenic amine biosynthesis has been observed in humans and animals with endogenous and exogenous disturbances in folate metabolism. In an attempt to study this interaction biochemically, rats were depleted or repleted with folate for 10 weeks. Folate levels in depleted animals in serum and CSF correlated with stores in liver and brain, respectively. In depleted or repleted animals, there was no significant effect on biogenic amine metabolism in the CNS, as determined by quantitation of biogenic amines in brain and their respective metabolites in brain and CSF. These results are contrary to studies by other investigators. We suspect, however, that specific genetic defects in folate metabolism do result in impaired biogenic amine metabolism and probably at the level of disturbed biopterin cofactor functions.     

Variables Controlling the Expression Level of Exogenous Genes in Dictyostelium

Ectopic expression of genes from recombinant plasmids is commonly used to study gene function. In Dictyostelium, three drug resistance cassettes are commonly used as selectable markers in vectors. We report here a comparative study of the expression of green fluorescent protein (GFP) gene from vectors containing each of the drug-resistant cassettes. The expression was highest in cells transformed with the vectors containing the neomycin-resistant cassette (pDNeoGFP), followed by the hygromycin-resistant cassette (pDHygGFP) and the blasticidin-resistant cassette (pDBsrGFP). The level of GFP expression was directly related to the copy number of the vector in transformants. In turn, the copy number of the vector depended on the drug resistance cassette as well as the concentration of the drug used in selection. In general, cells with higher copy numbers could be selected by a higher drug concentration. The expression of GFP was also affected by the method of transformation. For pDHygGFP, expression of GFP was much higher in cells transformed by electroporation than those transformed by calcium phosphate coprecipitation. However, only a slight difference was observed for pDNeoGFP or pDBsrGFP.     

Advances in Biochemical Screening for Phaeochromocytoma using Biogenic Amines

Biochemical testing for phaeochromocytoma is performed in diagnostic laboratories using a variety of tests with plasma, serum or 24-hour urine collections. These tests include catecholamines and their methylated metabolites - the metanephrines, either individually or in combination with their sulfated metabolites. High-performance liquid chromatography (HPLC) continues to be the dominant analytical method for biogenic amine quantitation. Chromatographic techniques are changing, with improvements in sample preparation procedures, column technology and more specific analyte detection using tandem mass spectrometry. Enrolments in quality assurance programs indicate that there are still many more laboratories in Australasia analysing urinary catecholamines than metanephrines. Nevertheless, clinical evidence and expert opinion favour metanephrines as the analytes with highest sensitivity for the detection of phaeochromocytoma. Practical issues such as better chemical stability and easier specimen collection also favour metanephrines over catecholamines. For these reasons, it is likely that laboratories increasingly will replace urine catecholamine testing with either plasma or urine metanephrines. However in interpreting positive results, the need remains to consider issues such as pre-test probability and use of potentially interfering medications.     

Novel Genes Involved in Controlling Specification of Drosophila FMRFamide Neuropeptide Cells

The expression of neuropeptides is often extremely restricted in the nervous system, making them powerful markers for addressing cell specification . In the developing Drosophila ventral nerve cord, only six cells, the Ap4 neurons, of some 10,000 neurons, express the neuropeptide FMRFamide (FMRFa). Each Ap4/FMRFa neuron is the last-born cell generated by an identifiable and well-studied progenitor cell, neuroblast 5-6 (NB5-6T). The restricted expression of FMRFa and the wealth of information regarding its gene regulation and Ap4 neuron specification makes FMRFa a valuable readout for addressing many aspects of neural development, i.e., spatial and temporal patterning cues, cell cycle control, cell specification, axon transport, and retrograde signaling. To this end, we have conducted a forward genetic screen utilizing an Ap4-specific FMRFa-eGFP transgenic reporter as our readout. A total of 9781 EMS-mutated chromosomes were screened for perturbations in FMRFa-eGFP expression, and 611 mutants were identified. Seventy-nine of the strongest mutants were mapped down to the affected gene by deficiency mapping or whole-genome sequencing. We isolated novel alleles for previously known FMRFa regulators, confirming the validity of the screen. In addition, we identified novel essential genes, including several with previously undefined functions in neural development. Our identification of genes affecting most major steps required for successful terminal differentiation of Ap4 neurons provides a comprehensive view of the genetic flow controlling the generation of highly unique neuronal cell types in the developing nervous system.     

Biogenic Amines Stimulate Regeneration of Cilia in Tetrahymena thermophila1

ABSTRACT Serotonin and catecholamines affect the regeneration of cilia in Tetrahymena thermophila in a dose-dependent manner: micromolar concentrations are stimulatory, whereas millimolar concentrations have little or no effect. This conclusion is based on motility measurements in regenerating cells and on ciliary counts in scanning electron micrographs. In addition, the recognition mechanism for each hormone appears to be specific and independent. Our results suggest an evolutionary link with hormonal mechanisms in multicellular eukaryotes.     

Effect of Biogenic Amines on Phagocytosis in Tetrahymena thermophila1

Stimulation of phagocytosis by serotonin and catecholamincs in Tetrahymena grown in proteose-peptone medium proved to be concentration dependent, the optimal concentrations being ∼0.1 to 1.0 μM. The serotonergic antagonists, spiperone, and metergoline, also stimulated the process, whereas the β- and α-adrenergic antagonists, propranolol, alprenolol, and ergocryptine, had no effect or inhibited phagocytosis. A wide variety of derivatives of the biogenic amines had no effect on phagocytosis, demonstrating the specificity of recognition mechanism for neurohormones in Tetrahymena. Such hormones act by at least two independent mechanisms, one for adrenergic agonists, another for dopamine. Presumably, recognition mechanisms for hormones in protozoa resemble in some respects those in multicellular organisms, therefore bespeaking a common origin.     

Amino Acids and Biogenic Amines in Cerebrospinal Fluid of Patients with Parkinson's Disease

To study changes in amino acid metabolism and biogenic amines in Parkinson's disease, we set up a prospective study and measured biogenic amines, their main metabolites, and 22 different amino acids, in cerebrospinal fluid of Parkinson's disease patients (n = 24) and age-matched controls (n = 30). A trend toward higher dopamine levels in Parkinson's disease patients was interpreted as an effect of treatment with levodopa and/or selegiline. Significantly lower concentrations of the dopamine metabolite 3,4-dihydroxyphenylacetic acid in the Parkinson's disease group might reflect dopaminergic cell loss. Our results revealed decreased serotonin catabolism that was interpreted as an effect of treatment with selegiline. Whereas all amino acid levels were unchanged, taurine was significantly lower in Parkinson's disease patients. Studies showed that taurine exerts a trophic action on the central nervous system. In this view, decreased taurine in a neurodegenerative disorder as Parkinson's disease deserves attention.     

Biogenic amines regulate the reproductive function in Drosophila as neurohormones

We studied the influence of experimental increase in the octopamine and dopamine content on the level of juvenile hormone degradation, oogenesis, and fertility in wild type D. virilis flies. Feeding of flies on octopamine led to a significantly decreased level of juvenile hormone degradation (increased titer) in young and sexually mature females, rather than in males, markedly decreased the number of vitellogenic (stages 8-10) and mature (stage 14) oocytes), and sharply reduced fertility. Feeding of flies on dopamine decreased the juvenile hormone degradation (increased titer) in young wild type females and increased it (lowered the juvenile hormone titer) in sexually mature females, as well as decreased the fertility of wild type females to a level characteristic for D. virilis line with a mutation doubling the endogenous dopamine level. A possible mechanism of the influence of these amines on the reproductive function in Drosophila as neurohormones is discussed and a conclusion is drawn that the reduced fertility of females at an increased level of amines appears to be related to an increased level of ecdysteroids, which is caused by an increased, as a result of decreased degradation, juvenile hormone titer.     

Biogenic amines in Drosophila virilis under stress conditions

The effect of heat stress (38 degrees C) on the content of DL-beta-(3,4-dihydroxyphenyl)alanine (DOPA), dopamine, tyramine, octopamine, and their precursor Tyr was studied in adults of two lines of Drosophila virilis contrasting in their stress response. In individuals of line 101 responding to stress by a hormonal stress reaction, the contents of DOPA, dopamine, octopamine, and Tyr were lower than those of line 147 that did not respond to the stress. However, heat stress caused an increase in the contents of DOPA, dopamine, octopamine, and Tyr in line 101, whereas the equivalent titers in line 147 remain unchanged.