Serotonin,Eating Behavior,and Fat Intake

There is an intimate relationship between nutritional intake (eating) and serotonin activity. Experimental manipulations (mainly neuropharmacological) of serotonin influence the pattern of eating behavior, subjective feelings of appetite motivation, and the response to nutritional challenges. Similarly, nutritional manipulations (food restriction, dieting, or altered nutrient supply) change the sensitivity of the serotonin network. Traditionally, serotonin has been linked to the macronutrient carbohydrate via the intermediary step of plasma amino acid ratios. However, it has also been demonstrated that 5-HT drugs will reduce energy intake and reverse body weight gain in rats exposed to weight increasing high fat diets. 5-HT drugs can also reduce food intake and block weight gain of rats on a high fat cafeteria diet. Some diet selection studies in rats indicate that the most prominent reduction of macronutrient intake is for fat. These data indicate that 5-HT activity can bring about a reduction in fat consumption. In turn, different types of dietary fat can alter brain 5-HT activity. In human studies the methodology of food choice experiments has often precluded the detection of an effect of 5-HT manipulation on fat intake. However, there is evidence that in obese and lean subjects some 5-HT drugs can readily reduce the intake of high fat foods. Data also suggest that 5-HT activation can lead to a selective avoidance of fat in the diet. These effects of 5-HT on the intake of dietary fat may involve a pre-absorptive mechanism and there is evidence that 5-HT is linked to cholecystokinin and enterostatin. These proposals have theoretical and practical implications and suggest possible strategies to intensify or advance fat-induced satiety signals.     

Putative Panmixia in Restricted Populations of Trypanosoma cruzi Isolated from Wild Triatoma infestans in Bolivia

Trypanosoma cruzi, the causative agent of Chagas disease, is subdivided into six discrete typing units (DTUs; TcI–TcVI) of which TcI is ubiquitous and genetically highly variable. While clonality is the dominant mode of propagation, recombinant events play a significant evolutive role. Recently, foci of wild Triatoma infestans have been described in Bolivia, mainly infected by TcI. Hence, for the first time, we evaluated the level of genetic exchange within TcI natural potentially panmictic populations (single DTU, host, area and sampling time). Seventy-nine TcI stocks from wild T. infestans, belonging to six populations were characterized at eight microsatellite loci. For each population, Hardy-Weinberg equilibrium (HWE), linkage disequilibrium (LD), and presence of repeated multilocus genotypes (MLG) were analyzed by using a total of seven statistics, to test the null hypothesis of panmixia (H₀). For three populations, none of the seven statistics allowed to rejecting H₀; for another one the low size did not allow us to conclude, and for the two others the tests have given contradictory results. Interestingly, apparent panmixia was only observed in very restricted areas, and was not observed when grouping populations distant of only two kilometers or more. Nevertheless it is worth stressing that for the statistic tests of "HWE", in order to minimize the type I error (i. e. incorrect rejection of a true H₀), we used the Bonferroni correction (BC) known to considerably increase the type II error ( i. e. failure to reject a false H₀). For the other tests (LD and MLG), we did not use BC and the risk of type II error in these cases was acceptable. Thus, these results should be considered as a good indicator of the existence of panmixia in wild environment but this must be confirmed on larger samples to reduce the risk of type II error.     

Nongenomic action of 1 alpha,25(OH)(2)-vitamin D3. Activation of muscle cell PLC gamma through the tyrosine kinase c-Src and PtdIns 3-kinase.

We have previously demonstrated that the steroid hormone 1 alpha,25(OH)(2)-vitamin D(3)[1 alpha,25(OH)(2)D(3)] stimulates the production of inositol trisphosphate (InsP(3)), the breakdown product of phosphatidylinositol 4,5-biphosphate (PtdInsP(2)) by phospholipase C (PtdIns-PLC), and activates the cytosolic tyrosine kinase c-Src in skeletal muscle cells. In the present study we examined whether 1 alpha,25(OH)(2)D(3) induces the phosphorylation and membrane translocation of PLC gamma and the mechanism involved in this isozyme activation. We found that the steroid hormone triggers a significant phosphorylation on tyrosine residues of PLC gamma and induces a rapid increase in membrane-associated PLC gamma immunoreactivity with a time course that correlates with that of phosphorylation in muscle cells. Genistein, a tyrosine kinase inhibitor, blocked the phosphorylation of PLC gamma. Inhibition of 1 alpha,25(OH)(2)D(3)-induced c-Src activity by its specific inhibitor PP1 or muscle cell transfection with an antisense oligodeoxynucleotide directed against c-Src mRNA, prevented hormone stimulation of PLC gamma tyrosine phosphorylation. The isozyme phosphorylation is also blocked by both wortmannin and LY294002, two structurally different inhibitors of phosphatidyl inositol 3-kinase (PtdIns3K), the enzyme that produces PtdInsP(3) known to activate PLC gamma isozymes specifically by interacting with their SH2 and pleckstrin homology domains. The hormone also increases the physical association of c-Src and PtdIns3K with PLC gamma and induces a c-Src-dependent tyrosine phosphorylation of the p85 regulatory subunit of PtdIns3K. The time course of hormone-dependent PLC gamma phosphorylation closely correlates with the time course of its redistribution to the membrane, suggesting that phosphorylation and redistribution to the membrane of PLC gamma are two interdependent events. 1 alpha,25(OH)(2)D(3)-induced membrane translocation of PLC gamma was prevented to a great extent by c-Src and PtdIns3K inhibitors, PP1 and LY294002. Taken together, the present data indicates that the cytosolic tyrosine kinase c-Src and PtdIns 3-kinase play indispensable roles in 1 alpha,25(OH)(2)D(3) signal transduction cascades leading to PLC gamma activation.     

Characterization of taxonomically restricted genes in a phylum-restricted cell type

Background  

Despite decades of research, the molecular mechanisms responsible for the evolution of morphological diversity remain poorly understood. While current models assume that species-specific morphologies are governed by differential use of conserved genetic regulatory circuits, it is debated whether non-conserved taxonomically restricted genes are also involved in making taxonomically relevant structures. The genomic resources available in Hydra, a member of the early branching animal phylum Cnidaria, provide a unique opportunity to study the molecular evolution of morphological novelties such as the nematocyte, a cell type characteristic of, and unique to, Cnidaria.     

Antidepressant-like profile and MAO-A inhibitory activity of 4-propyl-2H-benzo[h]-chromen-2-one

AimsTo evaluate the central nervous pharmacological profile of 4-propyl-2H-benzo[h]-chromen-2-one (FCS-304) in ICR mice and its monoamine oxidase inhibitor activity.Main methodsFCS-304 was evaluated in screening test of central nervous system in ICR mice and against MAO activity.Key findingsFCS-304 (25–200 mg/Kg, p.o.) significantly reduced immobility time during the forced swimming test (FST) and tail suspension test (TST), but did not show effects in the rota-rod tests, maximal electroshock seizures (MES), pentylenetetrazole seizures, light–dark box, barbiturate sleeping time and cold plate tests. Furthermore, FCS-304 inhibited monoamine oxidase A (MAO-A) with IC₅₀: 2.28 ± 0.15 µM, but not MAO-B.SignificanceThese results suggest that FCS-304 could elicit antidepressant effects related to MAO-A inhibitory activity.     

Pregnancy success of lactating Holstein cows after a single administration of a sustained-release formulation of recombinant bovine somatotropin

Background

Results regarding the use of bovine somatotropin for enhancing fertility in dairy cattle are variable. Here, the hypothesis was tested that a single injection of a sustained-release preparation of bovine somatotropin (bST) during the preovulatory period would improve pregnancy success of lactating dairy cows at first service.

Results

The first experiment was conducted in a temperate region of Mexico. Cows inseminated following natural estrus or timed artificial insemination were given a single injection of bST or a placebo injection at insemination (n = 100 cows per group). There was no significant difference between bST and control groups in the proportion of inseminated cows diagnosed pregnant (29 vs 31% pregnant). The second experiment was performed during heat stress in Florida. Cows were subjected to an ovulation synchronization regimen for first insemination. Cows treated with bST received a single injection at 3 days before insemination. Controls received no additional treatment. As expected, bST did not increase vaginal temperature. Treatment with bST did not significantly increase the proportion of inseminated cows diagnosed pregnant although it was numerically greater for the bST group (24.2% vs 17.8%, 124–132 cows per group). There was a tendency (p = 0.10) for a smaller percent of control cows to have high plasma progesterone concentrations (≥ 1 ng/ml) at Day 7 after insemination than for bST-treated cows (72.6 vs 81.1%). When only cows that were successfully synchronized were considered, the magnitude of the absolute difference in the percentage of inseminated cows that were diagnosed pregnant between bST and control cows was reduced (24.8 vs 22.4% pregnant for bST and control).

Conclusion

Results failed to indicate a beneficial effect of bST treatment on fertility of lactating dairy cows.