A simple, sensitive and reliable assay for serotonin and 5-HIAA in brain tissue using liquid chromatography with electrochemical detection

An extremely sensitive and simple method for simultaneously measuring both serotonin and 5-hydroxyindoleacetic acid (5-HIAA) has been developed using liquid chromatography (LC) and electrochemical detection. Assay conditions are described which resolve and measure as little as 22 picograms of serotonin and its deaminated metabolite in deproteinated brain samples.     

Drugs That Cause Weight Gain

Among drugs which cause weight gain, the tricyclic antidepressant medications are a drug class producing persistent and problematic body weight gain in many treated patients. Major depressive illness is often associated with reductions in appetite and body weight, and treatment with antidepressants effectively restores mood, appetite and weight. However, a frequent complaint of patients treated with tricyclic drugs is of excessive and unwanted weight gain, oftentimes resulting in medication noncompliance. The incidence of weight gain during acute and chronic treatment with different, frequently prescribed antidepressant drugs will be reviewed, as will the possible mechanisms by which such drugs alter caloric intake and expenditure, contributing to drug-induced weight gain.     

A major difference between the divergence patterns within the lines-1 families in mice and voles

L1 retroposons are represented in mice by subfamilies of interspersed sequences of varied abundance. Previous analyses have indicated that subfamilies are generated by duplicative transposition of a small number of members of the L1 family, the progeny of which then become a major component of the murine L1 population, and are not due to any active processes generating homology within preexisting groups of elements in a particular species. In mice, more than a third of the L1 elements belong to a clade that became active approximately 5 Mya and whose elements are > or = 95% identical. We have collected sequence information from 13 L1 elements isolated from two species of voles (Rodentia: Microtinae: Microtus and Arvicola) and have found that divergence within the vole L1 population is quite different from that in mice, in that there is no abundant subfamily of homologous elements. Individual L1 elements from voles are very divergent from one another and belong to a clade that began a period of elevated duplicative transposition approximately 13 Mya. Sequence analyses of portions of these divergent L1 elements (approximately 250 bp each) gave no evidence for concerted evolution having acted on the vole L1 elements since the split of the two vole lineages approximately 3.5 Mya; that is, the observed interspecific divergence (6.7%-24.7%) is not larger than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses showed no clustering into Arvicola and Microtus clades.      

Neutral amino acids in the brain: changes in response to food ingestion

Abstract— The brain levels of each of the aromatic and branched-chain amino acids change 2 h after fasting rats begin to consume either a carbohydrate-fat diet or a similar diet containing 18% or 40% protein. Carbohydrate-fat ingestion elevates the concentrations of each of the aromatic amino acids in brain, while substantially depressing those of the branched-chain amino acids. The inclusion of protein in this diet suppresses the increases in brain aromatic amino acids and attenuates the decreases in the branched-chain amino acids. The changes in the brain level of each neutral amino acid following the ingestion of any of these diets correlate extremely well with the effects of the diet on the serum neutral amino acid pattern, specifically on the serum concentration ratio of each neutral amino acid to the sum of the other neutral amino acids. The diet-induced changes in the brain level of each of the amino acids also correlate surprisingly well with the calculated rate of brain influx for each amino acid.     

Salicylate reduces serum insulin concentrations in the rat

Administration of sodium salicylate (50–500 mg/kg, i.p.) reduced serum insulin concentrations in nonfasted rats. This treatment also suppressed the rise in serum insulin that followed oral administration of glucose (by stomach tube) to fasted rats; this effect is only partly attributable to the blunted increase in serum glucose concentrations.     

EFFECTS OF INGESTION OF A CARBOHYDRATE-FAT MEAL ON THE LEVELS AND SYNTHESIS OF 5-HYDROXYINDOLES IN VARIOUS REGIONS OF THE RAT CENTRAL NERVOUS SYSTEM

—The concentrations of tryptophan, serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in spinal cord and most brain regions increase 2 h after fasted rats begin to consume a carbohydrate-fat meal: indole levels rise in all portions of the brain studied, but the increase is not statistically significant in the hypothalamus and corpus striatum. The rate at which the brain synthesizes 5-hydroxy-indoles (as estimated in vivo by measuring 5-hydroxytryptophan accumulation following an injection of the decarboxylase inhibitor RO4-4602) is also accelerated in all of the regions in which the experimental diet elevates tryptophan, 5-HT and 5-HIAA levels. These observations indicate that the previously reported increase in brain 5-hydroxyindole levels following consumption of a protein-free meal reflects accelerated serotonin synthesis, and occurs within both the cell bodies and the terminals of serotonin-containing neurons. It is possible that diet-induced changes in neuronal serotonin levels influence the quantities of the neurotransmitter released into synapses, either spontaneously or in response to drugs.     

Multifactorial diversity sustains microbial community stability

Maintenance of a high degree of biodiversity in homogeneous environments is poorly understood. A complex cheese starter culture with a long history of use was characterized as a model system to study simple microbial communities. Eight distinct genetic lineages were identified, encompassing two species: Lactococcus lactis and Leuconostoc mesenteroides. The genetic lineages were found to be collections of strains with variable plasmid content and phage sensitivities. Kill-the-winner hypothesis explaining the suppression of the fittest strains by density-dependent phage predation was operational at the strain level. This prevents the eradication of entire genetic lineages from the community during propagation regimes (back-slopping), stabilizing the genetic heterogeneity in the starter culture against environmental uncertainty.     

Immunohistochemical localization of irisin in skin,eye, and thyroid and pineal glands of the crested porcupine (Hystrix cristata)

Irisin was first identified in muscle cells. We detected irisin immunoreactivity in various organs of the crested porcupine (Hystrix cristata). In the epidermis, irisin immunoreactivity was localized mainly in stratum basale, stratum spinosum and stratum granulosum layers; immunoreactivity was not observed in the stratum corneum. In the dermis, irisin was found in the external and internal root sheath, cortex and medulla of hair follicles, and in sebaceous glands. Irisin immunoreactivity was found in the neural retina and skeletal muscle fibers associated with the eye. The pineal and thyroid glands also exhibited irisin immunoreactivity.