Origin and functional role of the extracellular serotonin in the midbrain raphe nuclei

There is considerable interest in the regulation of the extracellular compartment of the transmitter serotonin (5-hydroxytryptamine, 5-HT) in the midbrain raphe nuclei because it can control the activity of ascending serotonergic systems and the release of 5-HT in terminal areas of the forebrain. Several intrinsic and extrinsic factors of 5-HT neurons that regulate 5-HT release in the dorsal (DR) and median (MnR) raphe nucleus are reviewed in this article. Despite its high concentration in the extracellular space of the raphe nuclei, the origin of this pool of the transmitter remains to be determined. Regardless of its origin, is has been shown that the release of 5-HT in the rostral raphe nuclei is partly dependent on impulse flow and Ca2+ ions. The release in the DR and MnR is critically dependent on the activation of 5-HT autoreceptors in these nuclei. Yet, it appears that 5-HT autoreceptors do not tonically inhibit 5-HT release in the raphe nuclei but rather play a role as sensors that respond to an excess of the endogenous transmitter. Both DR and MnR are equally responsive to the reduction of 5-HT release elicited by the local perfusion of 5-HT1A receptor agonists. In contrast, the effects of selective 5-HT1B receptor agonists are more pronounced in the MnR than in the DR. However, the cellular localization of 5-HT1B receptors in the raphe nuclei remains to be established. Furthermore, endogenous noradrenaline and GABA tonically regulate the extracellular concentration of 5-HT although the degree of tonicity appears to depend upon the sleep/wake cycle and the behavioral state of the animal. Glutamate exerts a phasic facilitatory control over the release of 5-HT in the raphe nuclei through ionotropic glutamate receptors. Overall, it appears that the extracellular concentration of 5-HT in the DR and the MnR is tightly controlled by intrinsic serotonergic mechanisms as well as afferent connections.Peer reviewe

Fish Oil Replacement by a Blend of Vegetable Oils in Diets for Juvenile Tench (Tinca tinca Linnaeus, 1758): Effects on Growth Performance and Whole-Body Composition

Among freshwater species, tench (Tinca tinca Linnaeus, 1758) is considered as a promising species for the diversification of aquaculture, but the intensification of techniques is necessary to promote and consolidate its culture. Adequate feeding in early growth phases is essential to face further grow-out. Fish oil (FO) is the main source of lipids in fish diets, but its production is unsustainable, and thus, alternative oils should be considered. A 90-day experiment was performed to evaluate the effects of partial and total replacement of cod liver oil (FO) by a blend of vegetable oils (VO) in juvenile tench. Six isonitrogenous and isolipidic diets with different levels of a VO blend containing 30% linseed oil, 20% corn oil, and 50% olive oil were tested: 0% (control), 20%VO, 40%VO, 60%VO, 80%VO, and 100%VO. With all diets, survival was 100%, and there were not differences in growth performance (total length (TL); weight (W); specific growth rate (SGR); feed conversion ratio (FCR); and biomass gain (BG)). Compared to the control group, whole-body lipid content decreased significantly in the 100%VO group. No differences in total saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids were found in the whole-body. The content of linolenic acid (ALA) in the whole-body increased as FO substitution did, being significantly higher with respect to control diet from 40% FO replacement diets. Nutritional indices, such as ΣPUFA/ΣSFA and Σn-6/Σn-3 ratios, tended to increase with increasing VO content, whereas the EPA + DHA showed an opposite trend. A total replacement of FO by the blend of VO did not affect the growth performance and fatty acid profile of juvenile tench. Further research on the effects of VO diet on nutritional quality in tench reared to commercial size should be performed

Fish Oil Replacement by Camelina (<i>Camelina sativa</i> L.) Oil in Diets for Juvenile Tench (<i>Tinca tinca</i> L.): Effects on Survival, Growth, and Whole-Body Fatty Acid Profile

Tench (Tinca tinca L.) plays a key role in the diversification of inland aquaculture, but its culture is mainly based on extensive culture systems with usually low and unpredictable yields. Rearing procedures under controlled conditions are essential to promote and consolidate tench production, and it is necessary to set up adequate feeding in early growth phases. Fish oil (FO) is currently the main source of lipids in aquafeeds, but considering the stagnation of smaller pelagic fisheries, alternative oils should be addressed. In a ninety-day experiment, the effects of partial and total replacement of FO with camelina oil (CO) on juvenile tench growth performance and whole-body composition were evaluated. Six isonitrogenous and isolipidic diets with different levels of CO were tested: 0% (control), 20%, 40%, 60%, 80%, and 100%. The survival rate was 100%, and no significant differences in growth performance (total length, weight, specific growth rate, feed conversion ratio, and biomass gain) were found. The lipid content in whole-body juveniles was significantly lower when juveniles were fed diets containing 40% and higher levels of CO than those fed the control diet whereas linolenic acid content was significantly higher. No differences in ΣSFA, ΣMUFA, ΣPUFA, Σn − 3, or Σn − 6 whole-body content were found. The nutritional indices ΣPUFA/ΣSFA and Σn − 6/Σn − 3 showed a linear increase trend with dietary CO inclusion whereas the EPA + DHA showed an opposite tendency. Compared to the control diet, EPA + DHA content (g kg−1) was significantly lower in juvenile tench fed a 100% CO diet, and Σn − 6/Σn − 3 was significantly higher in juvenile tench fed 80% and 100% CO diets. Overall, the results indicate that the total replacement of FO with CO in diets is feasible without negative effects on growth performance whereas the nutritional quality of juvenile tench was unaffected with a maximum replacement of 80%

Perspectives on the ethical concerns and justifications of the 2006 Centers for Disease Control and Prevention HIV testing recommendations

<p>Abstract</p> <p>Background</p> <p>In 2006, the Centers for Disease Control and Prevention (CDC) recommended three changes to HIV testing methods in US healthcare settings: (1) an opt-out approach, (2) removal of separate signed consent, and (3) optional HIV prevention counseling. These recommendations led to a public debate about their moral acceptability.</p> <p>Methods</p> <p>We interviewed 25 members from the fields of US HIV advocacy, care, policy, and research about the ethical merits and demerits of the three changes to HIV testing methods. We performed a qualitative analysis of the participant responses in the interviews and summarized the major themes.</p> <p>Results</p> <p>In general, arguments in favor of the methods were based upon their ultimate contribution to increasing HIV testing and permitting the consequent benefits of identifying those who are HIV infected and linking them to further care.</p> <p>Conclusions</p> <p>The prevailing theme of ethical concern focused on suspicions that the methods might not be properly implemented, and that further safeguards might be needed.</p